third-party/leptonica/src/blend.c
/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
- 1. Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- 2. Redistributions in binary form must reproduce the above
- copyright notice, this list of conditions and the following
- disclaimer in the documentation and/or other materials
- provided with the distribution.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANY
- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*====================================================================*/
/*
* blend.c
*
* Blending two images that are not colormapped
* PIX *pixBlend()
* PIX *pixBlendMask()
* PIX *pixBlendGray()
* PIX *pixBlendGrayInverse()
* PIX *pixBlendColor()
* PIX *pixBlendColorByChannel()
* PIX *pixBlendGrayAdapt()
* static l_int32 blendComponents()
* PIX *pixFadeWithGray()
* PIX *pixBlendHardLight()
* static l_int32 blendHardLightComponents()
*
* Blending two colormapped images
* l_int32 pixBlendCmap()
*
* Blending two images using a third (alpha mask)
* PIX *pixBlendWithGrayMask()
*
* Blending background to a specific color
* PIX *pixBlendBackgroundToColor()
*
* Multiplying by a specific color
* PIX *pixMultiplyByColor()
*
* Rendering with alpha blending over a uniform background
* PIX *pixAlphaBlendUniform()
*
* Adding an alpha layer for blending
* PIX *pixAddAlphaToBlend()
*
* Setting a transparent alpha component over a white background
* PIX *pixSetAlphaOverWhite()
*
* In blending operations a new pix is produced where typically
* a subset of pixels in src1 are changed by the set of pixels
* in src2, when src2 is located in a given position relative
* to src1. This is similar to rasterop, except that the
* blending operations we allow are more complex, and typically
* result in dest pixels that are a linear combination of two
* pixels, such as src1 and its inverse. I find it convenient
* to think of src2 as the "blender" (the one that takes the action)
* and src1 as the "blendee" (the one that changes).
*
* Blending works best when src1 is 8 or 32 bpp. We also allow
* src1 to be colormapped, but the colormap is removed before blending,
* so if src1 is colormapped, we can't allow in-place blending.
*
* Because src2 is typically smaller than src1, we can implement by
* clipping src2 to src1 and then transforming some of the dest
* pixels that are under the support of src2. In practice, we
* do the clipping in the inner pixel loop. For grayscale and
* color src2, we also allow a simple form of transparency, where
* pixels of a particular value in src2 are transparent; for those pixels,
* no blending is done.
*
* The blending functions are categorized by the depth of src2,
* the blender, and not that of src1, the blendee.
*
* - If src2 is 1 bpp, we can do one of three things:
* (1) L_BLEND_WITH_INVERSE: Blend a given fraction of src1 with its
* inverse color for those pixels in src2 that are fg (ON),
* and leave the dest pixels unchanged for pixels in src2 that
* are bg (OFF).
* (2) L_BLEND_TO_WHITE: Fade the src1 pixels toward white by a
* given fraction for those pixels in src2 that are fg (ON),
* and leave the dest pixels unchanged for pixels in src2 that
* are bg (OFF).
* (3) L_BLEND_TO_BLACK: Fade the src1 pixels toward black by a
* given fraction for those pixels in src2 that are fg (ON),
* and leave the dest pixels unchanged for pixels in src2 that
* are bg (OFF).
* The blending function is pixBlendMask().
*
* - If src2 is 8 bpp grayscale, we can do one of two things
* (but see pixFadeWithGray() below):
* (1) L_BLEND_GRAY: If src1 is 8 bpp, mix the two values, using
* a fraction of src2 and (1 - fraction) of src1.
* If src1 is 32 bpp (rgb), mix the fraction of src2 with
* each of the color components in src1.
* (2) L_BLEND_GRAY_WITH_INVERSE: Use the grayscale value in src2
* to determine how much of the inverse of a src1 pixel is
* to be combined with the pixel value. The input fraction
* further acts to scale the change in the src1 pixel.
* The blending function is pixBlendGray().
*
* - If src2 is color, we blend a given fraction of src2 with
* src1. If src1 is 8 bpp, the resulting image is 32 bpp.
* The blending function is pixBlendColor().
*
* - For all three blending functions -- pixBlendMask(), pixBlendGray()
* and pixBlendColor() -- you can apply the blender to the blendee
* either in-place or generating a new pix. For the in-place
* operation, this requires that the depth of the resulting pix
* must equal that of the input pixs1.
*
* - We remove colormaps from src1 and src2 before blending.
* Any quantization would have to be done after blending.
*
* We include another function, pixFadeWithGray(), that blends
* a gray or color src1 with a gray src2. It does one of these things:
* (1) L_BLEND_TO_WHITE: Fade the src1 pixels toward white by
* a number times the value in src2.
* (2) L_BLEND_TO_BLACK: Fade the src1 pixels toward black by
* a number times the value in src2.
*
* Also included is a generalization of the so-called "hard light"
* blending: pixBlendHardLight(). We generalize by allowing a fraction < 1.0
* of the blender to be admixed with the blendee. The standard function
* does full mixing.
*/
#include "allheaders.h"
static l_int32 blendComponents(l_int32 a, l_int32 b, l_float32 fract);
static l_int32 blendHardLightComponents(l_int32 a, l_int32 b, l_float32 fract);
/*-------------------------------------------------------------*
* Blending two images that are not colormapped *
*-------------------------------------------------------------*/
/*!
* pixBlend()
*
* Input: pixs1 (blendee)
* pixs2 (blender; typ. smaller)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1; can be < 0)
* fract (blending fraction)
* Return: pixd (blended image), or null on error
*
* Notes:
* (1) This is a simple top-level interface. For more flexibility,
* call directly into pixBlendMask(), etc.
*/
PIX *
pixBlend(PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract)
{
l_int32 w1, h1, d1, d2;
BOX *box;
PIX *pixc, *pixt, *pixd;
PROCNAME("pixBlend");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, NULL);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, NULL);
/* check relative depths */
d1 = pixGetDepth(pixs1);
d2 = pixGetDepth(pixs2);
if (d1 == 1 && d2 > 1)
return (PIX *)ERROR_PTR("mixing gray or color with 1 bpp",
procName, NULL);
/* remove colormap from pixs2 if necessary */
pixt = pixRemoveColormap(pixs2, REMOVE_CMAP_BASED_ON_SRC);
d2 = pixGetDepth(pixt);
/* Check if pixs2 is clipped by its position with respect
* to pixs1; if so, clip it and redefine x and y if necessary.
* This actually isn't necessary, as the specific blending
* functions do the clipping directly in the pixel loop
* over pixs2, but it's included here to show how it can
* easily be done on pixs2 first. */
pixGetDimensions(pixs1, &w1, &h1, NULL);
box = boxCreate(-x, -y, w1, h1); /* box of pixs1 relative to pixs2 */
pixc = pixClipRectangle(pixt, box, NULL);
boxDestroy(&box);
if (!pixc) {
L_WARNING("box doesn't overlap pix\n", procName);
return NULL;
}
x = L_MAX(0, x);
y = L_MAX(0, y);
if (d2 == 1) {
pixd = pixBlendMask(NULL, pixs1, pixc, x, y, fract,
L_BLEND_WITH_INVERSE);
} else if (d2 == 8) {
pixd = pixBlendGray(NULL, pixs1, pixc, x, y, fract,
L_BLEND_GRAY, 0, 0);
} else { /* d2 == 32 */
pixd = pixBlendColor(NULL, pixs1, pixc, x, y, fract, 0, 0);
}
pixDestroy(&pixc);
pixDestroy(&pixt);
return pixd;
}
/*!
* pixBlendMask()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee, depth > 1)
* pixs2 (blender, 1 bpp; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1; can be < 0)
* fract (blending fraction)
* type (L_BLEND_WITH_INVERSE, L_BLEND_TO_WHITE, L_BLEND_TO_BLACK)
* Return: pixd if OK; null on error
*
* Notes:
* (1) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (2) If pixs1 has a colormap, it is removed.
* (3) For inplace operation (pixs1 not cmapped), call it this way:
* pixBlendMask(pixs1, pixs1, pixs2, ...)
* (4) For generating a new pixd:
* pixd = pixBlendMask(NULL, pixs1, pixs2, ...)
* (5) Only call in-place if pixs1 does not have a colormap.
* (6) Invalid @fract defaults to 0.5 with a warning.
* Invalid @type defaults to L_BLEND_WITH_INVERSE with a warning.
*/
PIX *
pixBlendMask(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract,
l_int32 type)
{
l_int32 i, j, d, wc, hc, w, h, wplc;
l_int32 val, rval, gval, bval;
l_uint32 pixval;
l_uint32 *linec, *datac;
PIX *pixc, *pix1, *pix2;
PROCNAME("pixBlendMask");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, NULL);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, NULL);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, NULL);
if (pixGetDepth(pixs2) != 1)
return (PIX *)ERROR_PTR("pixs2 not 1 bpp", procName, NULL);
if (pixd == pixs1 && pixGetColormap(pixs1))
return (PIX *)ERROR_PTR("inplace; pixs1 has colormap", procName, NULL);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, NULL);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
if (type != L_BLEND_WITH_INVERSE && type != L_BLEND_TO_WHITE &&
type != L_BLEND_TO_BLACK) {
L_WARNING("invalid blend type; setting to L_BLEND_WITH_INVERSE\n",
procName);
type = L_BLEND_WITH_INVERSE;
}
/* If pixd != NULL, we know that it is equal to pixs1 and
* that pixs1 does not have a colormap, so that an in-place operation
* can be done. Otherwise, remove colormap from pixs1 if
* it exists and unpack to at least 8 bpp if necessary,
* to do the blending on a new pix. */
if (!pixd) {
pix1 = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
if (pixGetDepth(pix1) < 8)
pix2 = pixConvertTo8(pix1, FALSE);
else
pix2 = pixClone(pix1);
pixd = pixCopy(NULL, pix2);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
pixGetDimensions(pixd, &w, &h, &d); /* d must be either 8 or 32 bpp */
pixc = pixClone(pixs2);
wc = pixGetWidth(pixc);
hc = pixGetHeight(pixc);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
/* Check limits for src1, in case clipping was not done. */
switch (type)
{
case L_BLEND_WITH_INVERSE:
/*
* The basic logic for this blending is:
* p --> (1 - f) * p + f * (1 - p)
* where p is a normalized value: p = pixval / 255.
* Thus,
* p --> p + f * (1 - 2 * p)
*/
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
bval = GET_DATA_BIT(linec, j);
if (bval) {
switch (d)
{
case 8:
pixGetPixel(pixd, x + j, y + i, &pixval);
val = (l_int32)(pixval + fract * (255 - 2 * pixval));
pixSetPixel(pixd, x + j, y + i, val);
break;
case 32:
pixGetPixel(pixd, x + j, y + i, &pixval);
extractRGBValues(pixval, &rval, &gval, &bval);
rval = (l_int32)(rval + fract * (255 - 2 * rval));
gval = (l_int32)(gval + fract * (255 - 2 * gval));
bval = (l_int32)(bval + fract * (255 - 2 * bval));
composeRGBPixel(rval, gval, bval, &pixval);
pixSetPixel(pixd, x + j, y + i, pixval);
break;
default:
L_WARNING("d neither 8 nor 32 bpp; no blend\n",
procName);
}
}
}
}
break;
case L_BLEND_TO_WHITE:
/*
* The basic logic for this blending is:
* p --> p + f * (1 - p) (p normalized to [0...1])
*/
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
bval = GET_DATA_BIT(linec, j);
if (bval) {
switch (d)
{
case 8:
pixGetPixel(pixd, x + j, y + i, &pixval);
val = (l_int32)(pixval + fract * (255 - pixval));
pixSetPixel(pixd, x + j, y + i, val);
break;
case 32:
pixGetPixel(pixd, x + j, y + i, &pixval);
extractRGBValues(pixval, &rval, &gval, &bval);
rval = (l_int32)(rval + fract * (255 - rval));
gval = (l_int32)(gval + fract * (255 - gval));
bval = (l_int32)(bval + fract * (255 - bval));
composeRGBPixel(rval, gval, bval, &pixval);
pixSetPixel(pixd, x + j, y + i, pixval);
break;
default:
L_WARNING("d neither 8 nor 32 bpp; no blend\n",
procName);
}
}
}
}
break;
case L_BLEND_TO_BLACK:
/*
* The basic logic for this blending is:
* p --> (1 - f) * p (p normalized to [0...1])
*/
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
bval = GET_DATA_BIT(linec, j);
if (bval) {
switch (d)
{
case 8:
pixGetPixel(pixd, x + j, y + i, &pixval);
val = (l_int32)((1. - fract) * pixval);
pixSetPixel(pixd, x + j, y + i, val);
break;
case 32:
pixGetPixel(pixd, x + j, y + i, &pixval);
extractRGBValues(pixval, &rval, &gval, &bval);
rval = (l_int32)((1. - fract) * rval);
gval = (l_int32)((1. - fract) * gval);
bval = (l_int32)((1. - fract) * bval);
composeRGBPixel(rval, gval, bval, &pixval);
pixSetPixel(pixd, x + j, y + i, pixval);
break;
default:
L_WARNING("d neither 8 nor 32 bpp; no blend\n",
procName);
}
}
}
}
break;
default:
L_WARNING("invalid binary mask blend type\n", procName);
break;
}
pixDestroy(&pixc);
return pixd;
}
/*!
* pixBlendGray()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee, depth > 1)
* pixs2 (blender, any depth; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1; can be < 0)
* fract (blending fraction)
* type (L_BLEND_GRAY, L_BLEND_GRAY_WITH_INVERSE)
* transparent (1 to use transparency; 0 otherwise)
* transpix (pixel grayval in pixs2 that is to be transparent)
* Return: pixd if OK; pixs1 on error
*
* Notes:
* (1) For inplace operation (pixs1 not cmapped), call it this way:
* pixBlendGray(pixs1, pixs1, pixs2, ...)
* (2) For generating a new pixd:
* pixd = pixBlendGray(NULL, pixs1, pixs2, ...)
* (3) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (4) If pixs1 has a colormap, it is removed; otherwise, if pixs1
* has depth < 8, it is unpacked to generate a 8 bpp pix.
* (5) If transparent = 0, the blending fraction (fract) is
* applied equally to all pixels.
* (6) If transparent = 1, all pixels of value transpix (typically
* either 0 or 0xff) in pixs2 are transparent in the blend.
* (7) After processing pixs1, it is either 8 bpp or 32 bpp:
* - if 8 bpp, the fraction of pixs2 is mixed with pixs1.
* - if 32 bpp, each component of pixs1 is mixed with
* the same fraction of pixs2.
* (8) For L_BLEND_GRAY_WITH_INVERSE, the white values of the blendee
* (cval == 255 in the code below) result in a delta of 0.
* Thus, these pixels are intrinsically transparent!
* The "pivot" value of the src, at which no blending occurs, is
* 128. Compare with the adaptive pivot in pixBlendGrayAdapt().
* (9) Invalid @fract defaults to 0.5 with a warning.
* Invalid @type defaults to L_BLEND_GRAY with a warning.
*/
PIX *
pixBlendGray(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract,
l_int32 type,
l_int32 transparent,
l_uint32 transpix)
{
l_int32 i, j, d, wc, hc, w, h, wplc, wpld, delta;
l_int32 ival, irval, igval, ibval, cval, dval;
l_uint32 val32;
l_uint32 *linec, *lined, *datac, *datad;
PIX *pixc, *pix1, *pix2;
PROCNAME("pixBlendGray");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, pixd);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, pixd);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, pixd);
if (pixd == pixs1 && pixGetColormap(pixs1))
return (PIX *)ERROR_PTR("can't do in-place with cmap", procName, pixd);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, pixd);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
if (type != L_BLEND_GRAY && type != L_BLEND_GRAY_WITH_INVERSE) {
L_WARNING("invalid blend type; setting to L_BLEND_GRAY\n", procName);
type = L_BLEND_GRAY;
}
/* If pixd != NULL, we know that it is equal to pixs1 and
* that pixs1 does not have a colormap, so that an in-place operation
* can be done. Otherwise, remove colormap from pixs1 if
* it exists and unpack to at least 8 bpp if necessary,
* to do the blending on a new pix. */
if (!pixd) {
pix1 = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
if (pixGetDepth(pix1) < 8)
pix2 = pixConvertTo8(pix1, FALSE);
else
pix2 = pixClone(pix1);
pixd = pixCopy(NULL, pix2);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
pixGetDimensions(pixd, &w, &h, &d); /* 8 or 32 bpp */
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
pixc = pixConvertTo8(pixs2, 0);
pixGetDimensions(pixc, &wc, &hc, NULL);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
/* Check limits for src1, in case clipping was not done */
if (type == L_BLEND_GRAY) {
/*
* The basic logic for this blending is:
* p --> (1 - f) * p + f * c
* where c is the 8 bpp blender. All values are normalized to [0...1].
*/
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
switch (d)
{
case 8:
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
if (transparent == 0 ||
(transparent != 0 && cval != transpix)) {
dval = GET_DATA_BYTE(lined, j + x);
ival = (l_int32)((1. - fract) * dval + fract * cval);
SET_DATA_BYTE(lined, j + x, ival);
}
}
break;
case 32:
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
if (transparent == 0 ||
(transparent != 0 && cval != transpix)) {
val32 = *(lined + j + x);
extractRGBValues(val32, &irval, &igval, &ibval);
irval = (l_int32)((1. - fract) * irval + fract * cval);
igval = (l_int32)((1. - fract) * igval + fract * cval);
ibval = (l_int32)((1. - fract) * ibval + fract * cval);
composeRGBPixel(irval, igval, ibval, &val32);
*(lined + j + x) = val32;
}
}
break;
default:
break; /* shouldn't happen */
}
}
} else { /* L_BLEND_GRAY_WITH_INVERSE */
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
switch (d)
{
case 8:
/*
* For 8 bpp, the dest pix is shifted by a signed amount
* proportional to the distance from 128 (the pivot value),
* and to the darkness of src2. If the dest is darker
* than 128, it becomes lighter, and v.v.
* The basic logic is:
* d --> d + f * (0.5 - d) * (1 - c)
* where d and c are normalized pixel values for src1 and
* src2, respectively, with 8 bit normalization to [0...1].
*/
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
if (transparent == 0 ||
(transparent != 0 && cval != transpix)) {
ival = GET_DATA_BYTE(lined, j + x);
delta = (128 - ival) * (255 - cval) / 256;
ival += (l_int32)(fract * delta + 0.5);
SET_DATA_BYTE(lined, j + x, ival);
}
}
break;
case 32:
/* Each component is shifted by the same formula for 8 bpp */
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
if (transparent == 0 ||
(transparent != 0 && cval != transpix)) {
val32 = *(lined + j + x);
extractRGBValues(val32, &irval, &igval, &ibval);
delta = (128 - irval) * (255 - cval) / 256;
irval += (l_int32)(fract * delta + 0.5);
delta = (128 - igval) * (255 - cval) / 256;
igval += (l_int32)(fract * delta + 0.5);
delta = (128 - ibval) * (255 - cval) / 256;
ibval += (l_int32)(fract * delta + 0.5);
composeRGBPixel(irval, igval, ibval, &val32);
*(lined + j + x) = val32;
}
}
break;
default:
break; /* shouldn't happen */
}
}
}
pixDestroy(&pixc);
return pixd;
}
/*!
* pixBlendGrayInverse()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee, depth > 1)
* pixs2 (blender, any depth; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1; can be < 0)
* fract (blending fraction)
* Return: pixd if OK; pixs1 on error
*
* Notes:
* (1) For inplace operation (pixs1 not cmapped), call it this way:
* pixBlendGrayInverse(pixs1, pixs1, pixs2, ...)
* (2) For generating a new pixd:
* pixd = pixBlendGrayInverse(NULL, pixs1, pixs2, ...)
* (3) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (4) If pixs1 has a colormap, it is removed; otherwise if pixs1
* has depth < 8, it is unpacked to generate a 8 bpp pix.
* (5) This is a no-nonsense blender. It changes the src1 pixel except
* when the src1 pixel is midlevel gray. Use fract == 1 for the most
* aggressive blending, where, if the gray pixel in pixs2 is 0,
* we get a complete inversion of the color of the src pixel in pixs1.
* (6) The basic logic is that each component transforms by:
d --> c * d + (1 - c ) * (f * (1 - d) + d * (1 - f))
* where c is the blender pixel from pixs2,
* f is @fract,
* c and d are normalized to [0...1]
* This has the property that for f == 0 (no blend) or c == 1 (white):
* d --> d
* For c == 0 (black) we get maximum inversion:
* d --> f * (1 - d) + d * (1 - f) [inversion by fraction f]
*/
PIX *
pixBlendGrayInverse(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract)
{
l_int32 i, j, d, wc, hc, w, h, wplc, wpld;
l_int32 irval, igval, ibval, cval, dval;
l_float32 a;
l_uint32 val32;
l_uint32 *linec, *lined, *datac, *datad;
PIX *pixc, *pix1, *pix2;
PROCNAME("pixBlendGrayInverse");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, pixd);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, pixd);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, pixd);
if (pixd == pixs1 && pixGetColormap(pixs1))
return (PIX *)ERROR_PTR("can't do in-place with cmap", procName, pixd);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, pixd);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
/* If pixd != NULL, we know that it is equal to pixs1 and
* that pixs1 does not have a colormap, so that an in-place operation
* can be done. Otherwise, remove colormap from pixs1 if
* it exists and unpack to at least 8 bpp if necessary,
* to do the blending on a new pix. */
if (!pixd) {
pix1 = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
if (pixGetDepth(pix1) < 8)
pix2 = pixConvertTo8(pix1, FALSE);
else
pix2 = pixClone(pix1);
pixd = pixCopy(NULL, pix2);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
pixGetDimensions(pixd, &w, &h, &d); /* 8 or 32 bpp */
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
pixc = pixConvertTo8(pixs2, 0);
pixGetDimensions(pixc, &wc, &hc, NULL);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
/* Check limits for src1, in case clipping was not done */
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
switch (d)
{
case 8:
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
dval = GET_DATA_BYTE(lined, j + x);
a = (1.0 - fract) * dval + fract * (255.0 - dval);
dval = (l_int32)(cval * dval / 255.0 +
a * (255.0 - cval) / 255.0);
SET_DATA_BYTE(lined, j + x, dval);
}
break;
case 32:
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
val32 = *(lined + j + x);
extractRGBValues(val32, &irval, &igval, &ibval);
a = (1.0 - fract) * irval + fract * (255.0 - irval);
irval = (l_int32)(cval * irval / 255.0 +
a * (255.0 - cval) / 255.0);
a = (1.0 - fract) * igval + fract * (255.0 - igval);
igval = (l_int32)(cval * igval / 255.0 +
a * (255.0 - cval) / 255.0);
a = (1.0 - fract) * ibval + fract * (255.0 - ibval);
ibval = (l_int32)(cval * ibval / 255.0 +
a * (255.0 - cval) / 255.0);
composeRGBPixel(irval, igval, ibval, &val32);
*(lined + j + x) = val32;
}
break;
default:
break; /* shouldn't happen */
}
}
pixDestroy(&pixc);
return pixd;
}
/*!
* pixBlendColor()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee; depth > 1)
* pixs2 (blender, any depth;; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1)
* fract (blending fraction)
* transparent (1 to use transparency; 0 otherwise)
* transpix (pixel color in pixs2 that is to be transparent)
* Return: pixd, or null on error
*
* Notes:
* (1) For inplace operation (pixs1 must be 32 bpp), call it this way:
* pixBlendColor(pixs1, pixs1, pixs2, ...)
* (2) For generating a new pixd:
* pixd = pixBlendColor(NULL, pixs1, pixs2, ...)
* (3) If pixs2 is not 32 bpp rgb, it is converted.
* (4) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (5) If pixs1 has a colormap, it is removed to generate a 32 bpp pix.
* (6) If pixs1 has depth < 32, it is unpacked to generate a 32 bpp pix.
* (7) If transparent = 0, the blending fraction (fract) is
* applied equally to all pixels.
* (8) If transparent = 1, all pixels of value transpix (typically
* either 0 or 0xffffff00) in pixs2 are transparent in the blend.
*/
PIX *
pixBlendColor(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract,
l_int32 transparent,
l_uint32 transpix)
{
l_int32 i, j, wc, hc, w, h, wplc, wpld;
l_int32 rval, gval, bval, rcval, gcval, bcval;
l_uint32 cval32, val32;
l_uint32 *linec, *lined, *datac, *datad;
PIX *pixc;
PROCNAME("pixBlendColor");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, NULL);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, NULL);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, NULL);
if (pixd == pixs1 && pixGetDepth(pixs1) != 32)
return (PIX *)ERROR_PTR("inplace; pixs1 not 32 bpp", procName, NULL);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, NULL);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
/* If pixd != null, we know that it is equal to pixs1 and
* that pixs1 is 32 bpp rgb, so that an in-place operation
* can be done. Otherwise, pixConvertTo32() will remove a
* colormap from pixs1 if it exists and unpack to 32 bpp
* (if necessary) to do the blending on a new 32 bpp Pix. */
if (!pixd)
pixd = pixConvertTo32(pixs1);
pixGetDimensions(pixd, &w, &h, NULL);
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
pixc = pixConvertTo32(pixs2); /* blend with 32 bpp rgb */
pixGetDimensions(pixc, &wc, &hc, NULL);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
/* Check limits for src1, in case clipping was not done */
for (i = 0; i < hc; i++) {
/*
* The basic logic for this blending is:
* p --> (1 - f) * p + f * c
* for each color channel. c is a color component of the blender.
* All values are normalized to [0...1].
*/
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval32 = *(linec + j);
if (transparent == 0 ||
(transparent != 0 &&
((cval32 & 0xffffff00) != (transpix & 0xffffff00)))) {
val32 = *(lined + j + x);
extractRGBValues(cval32, &rcval, &gcval, &bcval);
extractRGBValues(val32, &rval, &gval, &bval);
rval = (l_int32)((1. - fract) * rval + fract * rcval);
gval = (l_int32)((1. - fract) * gval + fract * gcval);
bval = (l_int32)((1. - fract) * bval + fract * bcval);
composeRGBPixel(rval, gval, bval, &val32);
*(lined + j + x) = val32;
}
}
}
pixDestroy(&pixc);
return pixd;
}
/*
* pixBlendColorByChannel()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee; depth > 1)
* pixs2 (blender, any depth; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1)
* rfract, gfract, bfract (blending fractions by channel)
* transparent (1 to use transparency; 0 otherwise)
* transpix (pixel color in pixs2 that is to be transparent)
* Return: pixd if OK; pixs1 on error
*
* Notes:
* (1) This generalizes pixBlendColor() in two ways:
* (a) The mixing fraction is specified per channel.
* (b) The mixing fraction may be < 0 or > 1, in which case,
* the min or max of two images are taken, respectively.
* (2) Specifically,
* for p = pixs1[i], c = pixs2[i], f = fract[i], i = 1, 2, 3:
* f < 0.0: p --> min(p, c)
* 0.0 <= f <= 1.0: p --> (1 - f) * p + f * c
* f > 1.0: p --> max(a, c)
* Special cases:
* f = 0: p --> p
* f = 1: p --> c
* (3) See usage notes in pixBlendColor()
* (4) pixBlendColor() would be equivalent to
* pixBlendColorChannel(..., fract, fract, fract, ...);
* at a small cost of efficiency.
*/
PIX *
pixBlendColorByChannel(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 rfract,
l_float32 gfract,
l_float32 bfract,
l_int32 transparent,
l_uint32 transpix)
{
l_int32 i, j, wc, hc, w, h, wplc, wpld;
l_int32 rval, gval, bval, rcval, gcval, bcval;
l_uint32 cval32, val32;
l_uint32 *linec, *lined, *datac, *datad;
PIX *pixc;
PROCNAME("pixBlendColorByChannel");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, pixd);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, pixd);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, pixd);
if (pixd == pixs1 && pixGetDepth(pixs1) != 32)
return (PIX *)ERROR_PTR("inplace; pixs1 not 32 bpp", procName, pixd);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, pixd);
/* If pixd != NULL, we know that it is equal to pixs1 and
* that pixs1 is 32 bpp rgb, so that an in-place operation
* can be done. Otherwise, pixConvertTo32() will remove a
* colormap from pixs1 if it exists and unpack to 32 bpp
* (if necessary) to do the blending on a new 32 bpp Pix. */
if (!pixd)
pixd = pixConvertTo32(pixs1);
pixGetDimensions(pixd, &w, &h, NULL);
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
pixc = pixConvertTo32(pixs2);
pixGetDimensions(pixc, &wc, &hc, NULL);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
/* Check limits for src1, in case clipping was not done */
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval32 = *(linec + j);
if (transparent == 0 ||
(transparent != 0 &&
((cval32 & 0xffffff00) != (transpix & 0xffffff00)))) {
val32 = *(lined + j + x);
extractRGBValues(cval32, &rcval, &gcval, &bcval);
extractRGBValues(val32, &rval, &gval, &bval);
rval = blendComponents(rval, rcval, rfract);
gval = blendComponents(gval, gcval, gfract);
bval = blendComponents(bval, bcval, bfract);
composeRGBPixel(rval, gval, bval, &val32);
*(lined + j + x) = val32;
}
}
}
pixDestroy(&pixc);
return pixd;
}
static l_int32
blendComponents(l_int32 a,
l_int32 b,
l_float32 fract)
{
if (fract < 0.)
return ((a < b) ? a : b);
if (fract > 1.)
return ((a > b) ? a : b);
return (l_int32)((1. - fract) * a + fract * b);
}
/*!
* pixBlendGrayAdapt()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee, depth > 1)
* pixs2 (blender, any depth; typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1; can be < 0)
* fract (blending fraction)
* shift (>= 0 but <= 128: shift of zero blend value from
* median source; use -1 for default value; )
* Return: pixd if OK; pixs1 on error
*
* Notes:
* (1) For inplace operation (pixs1 not cmapped), call it this way:
* pixBlendGrayAdapt(pixs1, pixs1, pixs2, ...)
* For generating a new pixd:
* pixd = pixBlendGrayAdapt(NULL, pixs1, pixs2, ...)
* (2) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (3) If pixs1 has a colormap, it is removed.
* (4) If pixs1 has depth < 8, it is unpacked to generate a 8 bpp pix.
* (5) This does a blend with inverse. Whereas in pixGlendGray(), the
* zero blend point is where the blendee pixel is 128, here
* the zero blend point is found adaptively, with respect to the
* median of the blendee region. If the median is < 128,
* the zero blend point is found from
* median + shift.
* Otherwise, if the median >= 128, the zero blend point is
* median - shift.
* The purpose of shifting the zero blend point away from the
* median is to prevent a situation in pixBlendGray() where
* the median is 128 and the blender is not visible.
* The default value of shift is 64.
* (6) After processing pixs1, it is either 8 bpp or 32 bpp:
* - if 8 bpp, the fraction of pixs2 is mixed with pixs1.
* - if 32 bpp, each component of pixs1 is mixed with
* the same fraction of pixs2.
* (7) The darker the blender, the more it mixes with the blendee.
* A blender value of 0 has maximum mixing; a value of 255
* has no mixing and hence is transparent.
*/
PIX *
pixBlendGrayAdapt(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract,
l_int32 shift)
{
l_int32 i, j, d, wc, hc, w, h, wplc, wpld, delta, overlap;
l_int32 rval, gval, bval, cval, dval, mval, median, pivot;
l_uint32 val32;
l_uint32 *linec, *lined, *datac, *datad;
l_float32 fmedian, factor;
BOX *box, *boxt;
PIX *pixc, *pix1, *pix2;
PROCNAME("pixBlendGrayAdapt");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, pixd);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, pixd);
if (pixGetDepth(pixs1) == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, pixd);
if (pixd == pixs1 && pixGetColormap(pixs1))
return (PIX *)ERROR_PTR("can't do in-place with cmap", procName, pixd);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("pixd must be NULL or pixs1", procName, pixd);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
if (shift == -1) shift = 64; /* default value */
if (shift < 0 || shift > 127) {
L_WARNING("invalid shift; setting to 64\n", procName);
shift = 64;
}
/* Test for overlap */
pixGetDimensions(pixs1, &w, &h, NULL);
pixGetDimensions(pixs2, &wc, &hc, NULL);
box = boxCreate(x, y, wc, hc);
boxt = boxCreate(0, 0, w, h);
boxIntersects(box, boxt, &overlap);
boxDestroy(&boxt);
if (!overlap) {
boxDestroy(&box);
return (PIX *)ERROR_PTR("no image overlap", procName, pixd);
}
/* If pixd != NULL, we know that it is equal to pixs1 and
* that pixs1 does not have a colormap, so that an in-place operation
* can be done. Otherwise, remove colormap from pixs1 if
* it exists and unpack to at least 8 bpp if necessary,
* to do the blending on a new pix. */
if (!pixd) {
pix1 = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
if (pixGetDepth(pix1) < 8)
pix2 = pixConvertTo8(pix1, FALSE);
else
pix2 = pixClone(pix1);
pixd = pixCopy(NULL, pix2);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
/* Get the median value in the region of blending */
pix1 = pixClipRectangle(pixd, box, NULL);
pix2 = pixConvertTo8(pix1, 0);
pixGetRankValueMasked(pix2, NULL, 0, 0, 1, 0.5, &fmedian, NULL);
median = (l_int32)(fmedian + 0.5);
if (median < 128)
pivot = median + shift;
else
pivot = median - shift;
pixDestroy(&pix1);
pixDestroy(&pix2);
boxDestroy(&box);
/* Process over src2; clip to src1. */
d = pixGetDepth(pixd);
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
pixc = pixConvertTo8(pixs2, 0);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
switch (d)
{
case 8:
/*
* For 8 bpp, the dest pix is shifted by an amount
* proportional to the distance from the pivot value,
* and to the darkness of src2. In no situation will it
* pass the pivot value in intensity.
* The basic logic is:
* d --> d + f * (np - d) * (1 - c)
* where np, d and c are normalized pixel values for
* the pivot, src1 and src2, respectively, with normalization
* to 255.
*/
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
dval = GET_DATA_BYTE(lined, j + x);
cval = GET_DATA_BYTE(linec, j);
delta = (pivot - dval) * (255 - cval) / 256;
dval += (l_int32)(fract * delta + 0.5);
SET_DATA_BYTE(lined, j + x, dval);
}
break;
case 32:
/*
* For 32 bpp, the dest pix is shifted by an amount
* proportional to the max component distance from the
* pivot value, and to the darkness of src2. Each component
* is shifted by the same fraction, either up or down,
* depending on the shift direction (which is toward the
* pivot). The basic logic for the red component is:
* r --> r + f * (np - m) * (1 - c) * (r / m)
* where np, r, m and c are normalized pixel values for
* the pivot, the r component of src1, the max component
* of src1, and src2, respectively, again with normalization
* to 255. Likewise for the green and blue components.
*/
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
cval = GET_DATA_BYTE(linec, j);
val32 = *(lined + j + x);
extractRGBValues(val32, &rval, &gval, &bval);
mval = L_MAX(rval, gval);
mval = L_MAX(mval, bval);
mval = L_MAX(mval, 1);
delta = (pivot - mval) * (255 - cval) / 256;
factor = fract * delta / mval;
rval += (l_int32)(factor * rval + 0.5);
gval += (l_int32)(factor * gval + 0.5);
bval += (l_int32)(factor * bval + 0.5);
composeRGBPixel(rval, gval, bval, &val32);
*(lined + j + x) = val32;
}
break;
default:
break; /* shouldn't happen */
}
}
pixDestroy(&pixc);
return pixd;
}
/*!
* pixFadeWithGray()
*
* Input: pixs (colormapped or 8 bpp or 32 bpp)
* pixb (8 bpp blender)
* factor (multiplicative factor to apply to blender value)
* type (L_BLEND_TO_WHITE, L_BLEND_TO_BLACK)
* Return: pixd, or null on error
*
* Notes:
* (1) This function combines two pix aligned to the UL corner; they
* need not be the same size.
* (2) Each pixel in pixb is multiplied by 'factor' divided by 255, and
* clipped to the range [0 ... 1]. This gives the fade fraction
* to be appied to pixs. Fade either to white (L_BLEND_TO_WHITE)
* or to black (L_BLEND_TO_BLACK).
*/
PIX *
pixFadeWithGray(PIX *pixs,
PIX *pixb,
l_float32 factor,
l_int32 type)
{
l_int32 i, j, w, h, d, wb, hb, db, wd, hd, wplb, wpld;
l_int32 valb, vald, nvald, rval, gval, bval, nrval, ngval, nbval;
l_float32 nfactor, fract;
l_uint32 val32, nval32;
l_uint32 *lined, *datad, *lineb, *datab;
PIX *pixd;
PROCNAME("pixFadeWithGray");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!pixb)
return (PIX *)ERROR_PTR("pixb not defined", procName, NULL);
if (pixGetDepth(pixs) == 1)
return (PIX *)ERROR_PTR("pixs is 1 bpp", procName, NULL);
pixGetDimensions(pixb, &wb, &hb, &db);
if (db != 8)
return (PIX *)ERROR_PTR("pixb not 8 bpp", procName, NULL);
if (factor < 0.0 || factor > 255.0)
return (PIX *)ERROR_PTR("factor not in [0.0...255.0]", procName, NULL);
if (type != L_BLEND_TO_WHITE && type != L_BLEND_TO_BLACK)
return (PIX *)ERROR_PTR("invalid fade type", procName, NULL);
/* Remove colormap if it exists; otherwise copy */
pixd = pixRemoveColormapGeneral(pixs, REMOVE_CMAP_BASED_ON_SRC, L_COPY);
pixGetDimensions(pixd, &wd, &hd, &d);
w = L_MIN(wb, wd);
h = L_MIN(hb, hd);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
datab = pixGetData(pixb);
wplb = pixGetWpl(pixb);
/* The basic logic for this blending is, for each component p of pixs:
* fade-to-white: p --> p + (f * c) * (1 - p)
* fade-to-black: p --> p - (f * c) * p
* with c being the 8 bpp blender pixel of pixb, and with both
* p and c normalized to [0...1]. */
nfactor = factor / 255.;
for (i = 0; i < h; i++) {
lineb = datab + i * wplb;
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
valb = GET_DATA_BYTE(lineb, j);
fract = nfactor * (l_float32)valb;
fract = L_MIN(fract, 1.0);
if (d == 8) {
vald = GET_DATA_BYTE(lined, j);
if (type == L_BLEND_TO_WHITE)
nvald = vald + (l_int32)(fract * (255. - (l_float32)vald));
else /* L_BLEND_TO_BLACK */
nvald = vald - (l_int32)(fract * (l_float32)vald);
SET_DATA_BYTE(lined, j, nvald);
} else { /* d == 32 */
val32 = lined[j];
extractRGBValues(val32, &rval, &gval, &bval);
if (type == L_BLEND_TO_WHITE) {
nrval = rval + (l_int32)(fract * (255. - (l_float32)rval));
ngval = gval + (l_int32)(fract * (255. - (l_float32)gval));
nbval = bval + (l_int32)(fract * (255. - (l_float32)bval));
} else {
nrval = rval - (l_int32)(fract * (l_float32)rval);
ngval = gval - (l_int32)(fract * (l_float32)gval);
nbval = bval - (l_int32)(fract * (l_float32)bval);
}
composeRGBPixel(nrval, ngval, nbval, &nval32);
lined[j] = nval32;
}
}
}
return pixd;
}
/*
* pixBlendHardLight()
*
* Input: pixd (<optional>; either NULL or equal to pixs1 for in-place)
* pixs1 (blendee; depth > 1, may be cmapped)
* pixs2 (blender, 8 or 32 bpp; may be colormapped;
* typ. smaller in size than pixs1)
* x,y (origin (UL corner) of pixs2 relative to
* the origin of pixs1)
* fract (blending fraction, or 'opacity factor')
* Return: pixd if OK; pixs1 on error
*
* Notes:
* (1) pixs2 must be 8 or 32 bpp; either may have a colormap.
* (2) Clipping of pixs2 to pixs1 is done in the inner pixel loop.
* (3) Only call in-place if pixs1 is not colormapped.
* (4) If pixs1 has a colormap, it is removed to generate either an
* 8 or 32 bpp pix, depending on the colormap.
* (5) For inplace operation, call it this way:
* pixBlendHardLight(pixs1, pixs1, pixs2, ...)
* (6) For generating a new pixd:
* pixd = pixBlendHardLight(NULL, pixs1, pixs2, ...)
* (7) This is a generalization of the usual hard light blending,
* where fract == 1.0.
* (8) "Overlay" blending is the same as hard light blending, with
* fract == 1.0, except that the components are switched
* in the test. (Note that the result is symmetric in the
* two components.)
* (9) See, e.g.:
* http://www.pegtop.net/delphi/articles/blendmodes/hardlight.htm
* http://www.digitalartform.com/imageArithmetic.htm
* (10) This function was built by Paco Galanes.
*/
PIX *
pixBlendHardLight(PIX *pixd,
PIX *pixs1,
PIX *pixs2,
l_int32 x,
l_int32 y,
l_float32 fract)
{
l_int32 i, j, w, h, d, wc, hc, dc, wplc, wpld;
l_int32 cval, dval, rcval, gcval, bcval, rdval, gdval, bdval;
l_uint32 cval32, dval32;
l_uint32 *linec, *lined, *datac, *datad;
PIX *pixc, *pixt;
PROCNAME("pixBlendHardLight");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, pixd);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, pixd);
pixGetDimensions(pixs1, &w, &h, &d);
pixGetDimensions(pixs2, &wc, &hc, &dc);
if (d == 1)
return (PIX *)ERROR_PTR("pixs1 is 1 bpp", procName, pixd);
if (dc != 8 && dc != 32)
return (PIX *)ERROR_PTR("pixs2 not 8 or 32 bpp", procName, pixd);
if (pixd && (pixd != pixs1))
return (PIX *)ERROR_PTR("inplace and pixd != pixs1", procName, pixd);
if (pixd == pixs1 && pixGetColormap(pixs1))
return (PIX *)ERROR_PTR("inplace and pixs1 cmapped", procName, pixd);
if (pixd && d != 8 && d != 32)
return (PIX *)ERROR_PTR("inplace and not 8 or 32 bpp", procName, pixd);
if (fract < 0.0 || fract > 1.0) {
L_WARNING("fract must be in [0.0, 1.0]; setting to 0.5\n", procName);
fract = 0.5;
}
/* If pixs2 has a colormap, remove it */
pixc = pixRemoveColormap(pixs2, REMOVE_CMAP_BASED_ON_SRC); /* clone ok */
dc = pixGetDepth(pixc);
/* There are 4 cases:
* * pixs1 has or doesn't have a colormap
* * pixc is either 8 or 32 bpp
* In all situations, if pixs has a colormap it must be removed,
* and pixd must have a depth that is equal to or greater than pixc. */
if (dc == 32) {
if (pixGetColormap(pixs1)) { /* pixd == NULL */
pixd = pixRemoveColormap(pixs1, REMOVE_CMAP_TO_FULL_COLOR);
} else {
if (!pixd) {
pixd = pixConvertTo32(pixs1);
} else {
pixt = pixConvertTo32(pixs1);
pixCopy(pixd, pixt);
pixDestroy(&pixt);
}
}
d = 32;
} else { /* dc == 8 */
if (pixGetColormap(pixs1)) /* pixd == NULL */
pixd = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
else
pixd = pixCopy(pixd, pixs1);
d = pixGetDepth(pixd);
}
if (!(d == 8 && dc == 8) && /* 3 cases only */
!(d == 32 && dc == 8) &&
!(d == 32 && dc == 32)) {
pixDestroy(&pixc);
return (PIX *)ERROR_PTR("bad! -- invalid depth combo!", procName, pixd);
}
wpld = pixGetWpl(pixd);
datad = pixGetData(pixd);
datac = pixGetData(pixc);
wplc = pixGetWpl(pixc);
for (i = 0; i < hc; i++) {
if (i + y < 0 || i + y >= h) continue;
linec = datac + i * wplc;
lined = datad + (i + y) * wpld;
for (j = 0; j < wc; j++) {
if (j + x < 0 || j + x >= w) continue;
if (d == 8 && dc == 8) {
dval = GET_DATA_BYTE(lined, x + j);
cval = GET_DATA_BYTE(linec, j);
dval = blendHardLightComponents(dval, cval, fract);
SET_DATA_BYTE(lined, x + j, dval);
} else if (d == 32 && dc == 8) {
dval32 = *(lined + x + j);
extractRGBValues(dval32, &rdval, &gdval, &bdval);
cval = GET_DATA_BYTE(linec, j);
rdval = blendHardLightComponents(rdval, cval, fract);
gdval = blendHardLightComponents(gdval, cval, fract);
bdval = blendHardLightComponents(bdval, cval, fract);
composeRGBPixel(rdval, gdval, bdval, &dval32);
*(lined + x + j) = dval32;
} else if (d == 32 && dc == 32) {
dval32 = *(lined + x + j);
extractRGBValues(dval32, &rdval, &gdval, &bdval);
cval32 = *(linec + j);
extractRGBValues(cval32, &rcval, &gcval, &bcval);
rdval = blendHardLightComponents(rdval, rcval, fract);
gdval = blendHardLightComponents(gdval, gcval, fract);
bdval = blendHardLightComponents(bdval, bcval, fract);
composeRGBPixel(rdval, gdval, bdval, &dval32);
*(lined + x + j) = dval32;
}
}
}
pixDestroy(&pixc);
return pixd;
}
/*
* blendHardLightComponents()
* Input: a (8 bpp blendee component)
* b (8 bpp blender component)
* fract (fraction of blending; use 1.0 for usual definition)
* Return: blended 8 bpp component
*
* Notes:
*
* The basic logic for this blending is:
* b < 0.5:
* a --> 2 * a * (0.5 - f * (0.5 - b))
* b >= 0.5:
* a --> 1 - 2 * (1 - a) * (1 - (0.5 - f * (0.5 - b)))
*
* In the limit that f == 1 (standard hardlight blending):
* b < 0.5: a --> 2 * a * b
* or
* a --> a - a * (1 - 2 * b)
* b >= 0.5: a --> 1 - 2 * (1 - a) * (1 - b)
* or
* a --> a + (1 - a) * (2 * b - 1)
*
* You can see that for standard hardlight blending:
* b < 0.5: a is pushed linearly with b down to 0
* b >= 0.5: a is pushed linearly with b up to 1
* a is unchanged if b = 0.5
*
* Our opacity factor f reduces the deviation of b from 0.5:
* f == 0: b --> 0.5, so no blending occurs
* f == 1: b --> b, so we get full conventional blending
*
* There is a variant of hardlight blending called "softlight" blending:
* (e.g., http://jswidget.com/blog/tag/hard-light/)
* b < 0.5:
* a --> a - a * (0.5 - b) * (1 - Abs(2 * a - 1))
* b >= 0.5:
* a --> a + (1 - a) * (b - 0.5) * (1 - Abs(2 * a - 1))
* which limits the amount that 'a' can be moved to a maximum of
* halfway toward 0 or 1, and further reduces it as 'a' moves
* away from 0.5.
* As you can see, there are a nearly infinite number of different
* blending formulas that can be conjured up.
*/
static l_int32 blendHardLightComponents(l_int32 a,
l_int32 b,
l_float32 fract)
{
if (b < 0x80) {
b = 0x80 - (l_int32)(fract * (0x80 - b));
return (a * b) >> 7;
} else {
b = 0x80 + (l_int32)(fract * (b - 0x80));
return 0xff - (((0xff - b) * (0xff - a)) >> 7);
}
}
/*-------------------------------------------------------------*
* Blending two colormapped images *
*-------------------------------------------------------------*/
/*!
* pixBlendCmap()
*
* Input: pixs (2, 4 or 8 bpp, with colormap)
* pixb (colormapped blender)
* x, y (UL corner of blender relative to pixs)
* sindex (colormap index of pixels in pixs to be changed)
* Return: 0 if OK, 1 on error
*
* Note:
* (1) This function combines two colormaps, and replaces the pixels
* in pixs that have a specified color value with those in pixb.
* (2) sindex must be in the existing colormap; otherwise an
* error is returned. In use, sindex will typically be the index
* for white (255, 255, 255).
* (3) Blender colors that already exist in the colormap are used;
* others are added. If any blender colors cannot be
* stored in the colormap, an error is returned.
* (4) In the implementation, a mapping is generated from each
* original blender colormap index to the corresponding index
* in the expanded colormap for pixs. Then for each pixel in
* pixs with value sindex, and which is covered by a blender pixel,
* the new index corresponding to the blender pixel is substituted
* for sindex.
*/
l_int32
pixBlendCmap(PIX *pixs,
PIX *pixb,
l_int32 x,
l_int32 y,
l_int32 sindex)
{
l_int32 rval, gval, bval;
l_int32 i, j, w, h, d, ncb, wb, hb, wpls;
l_int32 index, val, nadded;
l_int32 lut[256];
l_uint32 pval;
l_uint32 *lines, *datas;
PIXCMAP *cmaps, *cmapb, *cmapsc;
PROCNAME("pixBlendCmap");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (!pixb)
return ERROR_INT("pixb not defined", procName, 1);
if ((cmaps = pixGetColormap(pixs)) == NULL)
return ERROR_INT("no colormap in pixs", procName, 1);
if ((cmapb = pixGetColormap(pixb)) == NULL)
return ERROR_INT("no colormap in pixb", procName, 1);
ncb = pixcmapGetCount(cmapb);
/* Make a copy of cmaps; we'll add to this if necessary
* and substitute at the end if we found there was enough room
* to hold all the new colors. */
cmapsc = pixcmapCopy(cmaps);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 2 && d != 4 && d != 8)
return ERROR_INT("depth not in {2,4,8}", procName, 1);
/* Add new colors if necessary; get mapping array between
* cmaps and cmapb. */
for (i = 0, nadded = 0; i < ncb; i++) {
pixcmapGetColor(cmapb, i, &rval, &gval, &bval);
if (pixcmapGetIndex(cmapsc, rval, gval, bval, &index)) { /* not found */
if (pixcmapAddColor(cmapsc, rval, gval, bval)) {
pixcmapDestroy(&cmapsc);
return ERROR_INT("not enough room in cmaps", procName, 1);
}
lut[i] = pixcmapGetCount(cmapsc) - 1;
nadded++;
} else {
lut[i] = index;
}
}
/* Replace cmaps if colors have been added. */
if (nadded == 0)
pixcmapDestroy(&cmapsc);
else
pixSetColormap(pixs, cmapsc);
/* Replace each pixel value sindex by mapped colormap index when
* a blender pixel in pixbc overlays it. */
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixGetDimensions(pixb, &wb, &hb, NULL);
for (i = 0; i < hb; i++) {
if (i + y < 0 || i + y >= h) continue;
lines = datas + (y + i) * wpls;
for (j = 0; j < wb; j++) {
if (j + x < 0 || j + x >= w) continue;
switch (d) {
case 2:
val = GET_DATA_DIBIT(lines, x + j);
if (val == sindex) {
pixGetPixel(pixb, j, i, &pval);
SET_DATA_DIBIT(lines, x + j, lut[pval]);
}
break;
case 4:
val = GET_DATA_QBIT(lines, x + j);
if (val == sindex) {
pixGetPixel(pixb, j, i, &pval);
SET_DATA_QBIT(lines, x + j, lut[pval]);
}
break;
case 8:
val = GET_DATA_BYTE(lines, x + j);
if (val == sindex) {
pixGetPixel(pixb, j, i, &pval);
SET_DATA_BYTE(lines, x + j, lut[pval]);
}
break;
default:
return ERROR_INT("depth not in {2,4,8}", procName, 1);
}
}
}
return 0;
}
/*---------------------------------------------------------------------*
* Blending two images using a third *
*---------------------------------------------------------------------*/
/*!
* pixBlendWithGrayMask()
*
* Input: pixs1 (8 bpp gray, rgb, rgba or colormapped)
* pixs2 (8 bpp gray, rgb, rgba or colormapped)
* pixg (<optional> 8 bpp gray, for transparency of pixs2;
* can be null)
* x, y (UL corner of pixs2 and pixg with respect to pixs1)
* Return: pixd (blended image), or null on error
*
* Notes:
* (1) The result is 8 bpp grayscale if both pixs1 and pixs2 are
* 8 bpp gray. Otherwise, the result is 32 bpp rgb.
* (2) pixg is an 8 bpp transparency image, where 0 is transparent
* and 255 is opaque. It determines the transparency of pixs2
* when applied over pixs1. It can be null if pixs2 is rgba,
* in which case we use the alpha component of pixs2.
* (3) If pixg exists, it need not be the same size as pixs2.
* However, we assume their UL corners are aligned with each other,
* and placed at the location (x, y) in pixs1.
* (4) The pixels in pixd are a combination of those in pixs1
* and pixs2, where the amount from pixs2 is proportional to
* the value of the pixel (p) in pixg, and the amount from pixs1
* is proportional to (255 - p). Thus pixg is a transparency
* image (usually called an alpha blender) where each pixel
* can be associated with a pixel in pixs2, and determines
* the amount of the pixs2 pixel in the final result.
* For example, if pixg is all 0, pixs2 is transparent and
* the result in pixd is simply pixs1.
* (5) A typical use is for the pixs2/pixg combination to be
* a small watermark that is applied to pixs1.
*/
PIX *
pixBlendWithGrayMask(PIX *pixs1,
PIX *pixs2,
PIX *pixg,
l_int32 x,
l_int32 y)
{
l_int32 w1, h1, d1, w2, h2, d2, spp, wg, hg, wmin, hmin, wpld, wpls, wplg;
l_int32 i, j, val, dval, sval;
l_int32 drval, dgval, dbval, srval, sgval, sbval;
l_uint32 dval32, sval32;
l_uint32 *datad, *datas, *datag, *lined, *lines, *lineg;
l_float32 fract;
PIX *pixr1, *pixr2, *pix1, *pix2, *pixg2, *pixd;
PROCNAME("pixBlendWithGrayMask");
if (!pixs1)
return (PIX *)ERROR_PTR("pixs1 not defined", procName, NULL);
if (!pixs2)
return (PIX *)ERROR_PTR("pixs2 not defined", procName, NULL);
pixGetDimensions(pixs1, &w1, &h1, &d1);
pixGetDimensions(pixs2, &w2, &h2, &d2);
if (d1 == 1 || d2 == 1)
return (PIX *)ERROR_PTR("pixs1 or pixs2 is 1 bpp", procName, NULL);
if (pixg) {
if (pixGetDepth(pixg) != 8)
return (PIX *)ERROR_PTR("pixg not 8 bpp", procName, NULL);
pixGetDimensions(pixg, &wg, &hg, NULL);
wmin = L_MIN(w2, wg);
hmin = L_MIN(h2, hg);
pixg2 = pixClone(pixg);
} else { /* use the alpha component of pixs2 */
spp = pixGetSpp(pixs2);
if (d2 != 32 || spp != 4)
return (PIX *)ERROR_PTR("no alpha; pixs2 not rgba", procName, NULL);
wmin = w2;
hmin = h2;
pixg2 = pixGetRGBComponent(pixs2, L_ALPHA_CHANNEL);
}
/* Remove colormaps if they exist; clones are OK */
pixr1 = pixRemoveColormap(pixs1, REMOVE_CMAP_BASED_ON_SRC);
pixr2 = pixRemoveColormap(pixs2, REMOVE_CMAP_BASED_ON_SRC);
/* Regularize to the same depth if necessary */
d1 = pixGetDepth(pixr1);
d2 = pixGetDepth(pixr2);
if (d1 == 32) { /* convert d2 to rgb if necessary */
pix1 = pixClone(pixr1);
if (d2 != 32)
pix2 = pixConvertTo32(pixr2);
else
pix2 = pixClone(pixr2);
} else if (d2 == 32) { /* and d1 != 32; convert to 32 */
pix2 = pixClone(pixr2);
pix1 = pixConvertTo32(pixr1);
} else { /* both are 8 bpp or less */
pix1 = pixConvertTo8(pixr1, FALSE);
pix2 = pixConvertTo8(pixr2, FALSE);
}
pixDestroy(&pixr1);
pixDestroy(&pixr2);
/* Sanity check */
d1 = pixGetDepth(pix1);
d2 = pixGetDepth(pix2);
if (d1 != d2) {
pixDestroy(&pix1);
pixDestroy(&pix2);
return (PIX *)ERROR_PTR("depths not regularized! bad!", procName, NULL);
}
/* Start with a copy of pix1 */
pixd = pixCopy(NULL, pix1);
pixDestroy(&pix1);
/* Blend pix2 onto pixd, using pixg2.
* Let the normalized pixel value of pixg2 be f = pixval / 255,
* and the pixel values of pixd and pix2 be p1 and p2, rsp.
* Then the blended value is:
* p = (1.0 - f) * p1 + f * p2
* Blending is done component-wise if rgb.
* Scan over pix2 and pixg2, clipping to pixd where necessary. */
datad = pixGetData(pixd);
datas = pixGetData(pix2);
datag = pixGetData(pixg2);
wpld = pixGetWpl(pixd);
wpls = pixGetWpl(pix2);
wplg = pixGetWpl(pixg2);
for (i = 0; i < hmin; i++) {
if (i + y < 0 || i + y >= h1) continue;
lined = datad + (i + y) * wpld;
lines = datas + i * wpls;
lineg = datag + i * wplg;
for (j = 0; j < wmin; j++) {
if (j + x < 0 || j + x >= w1) continue;
val = GET_DATA_BYTE(lineg, j);
if (val == 0) continue; /* pix2 is transparent */
fract = (l_float32)val / 255.;
switch (d1) {
case 8:
dval = GET_DATA_BYTE(lined, j + x);
sval = GET_DATA_BYTE(lines, j);
dval = (l_int32)((1.0 - fract) * dval + fract * sval);
SET_DATA_BYTE(lined, j + x, dval);
break;
case 32:
dval32 = *(lined + j + x);
sval32 = *(lines + j);
extractRGBValues(dval32, &drval, &dgval, &dbval);
extractRGBValues(sval32, &srval, &sgval, &sbval);
drval = (l_int32)((1.0 - fract) * drval + fract * srval);
dgval = (l_int32)((1.0 - fract) * dgval + fract * sgval);
dbval = (l_int32)((1.0 - fract) * dbval + fract * sbval);
composeRGBPixel(drval, dgval, dbval, &dval32);
*(lined + j + x) = dval32;
break;
default:
return (PIX *)ERROR_PTR("impossible error", procName, NULL);
}
}
}
pixDestroy(&pixg2);
pixDestroy(&pix2);
return pixd;
}
/*---------------------------------------------------------------------*
* Blending background to a specific color *
*---------------------------------------------------------------------*/
/*!
* pixBlendBackgroundToColor()
*
* Input: pixd (can be NULL or pixs)
* pixs (32 bpp rgb)
* box (region for blending; can be NULL))
* color (32 bit color in 0xrrggbb00 format)
* gamma, minval, maxval (args for grayscale TRC mapping)
* Return: pixd always
*
* Notes:
* (1) This in effect replaces light background pixels in pixs
* by the input color. It does it by alpha blending so that
* there are no visible artifacts from hard cutoffs.
* (2) If pixd == pixs, this is done in-place.
* (3) If box == NULL, this is performed on all of pixs.
* (4) The alpha component for blending is derived from pixs,
* by converting to grayscale and enhancing with a TRC.
* (5) The last three arguments specify the TRC operation.
* Suggested values are: @gamma = 0.3, @minval = 50, @maxval = 200.
* To skip the TRC, use @gamma == 1, @minval = 0, @maxval = 255.
* See pixGammaTRC() for details.
*/
PIX *
pixBlendBackgroundToColor(PIX *pixd,
PIX *pixs,
BOX *box,
l_uint32 color,
l_float32 gamma,
l_int32 minval,
l_int32 maxval)
{
l_int32 x, y, w, h;
BOX *boxt;
PIX *pixt, *pixc, *pixr, *pixg;
PROCNAME("pixBlendBackgroundToColor");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs not 32 bpp", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd neither null nor pixs", procName, pixd);
/* Extract the (optionally cropped) region, pixr, and generate
* an identically sized pixc with the uniform color. */
if (!pixd)
pixd = pixCopy(NULL, pixs);
if (box) {
pixr = pixClipRectangle(pixd, box, &boxt);
boxGetGeometry(boxt, &x, &y, &w, &h);
pixc = pixCreate(w, h, 32);
boxDestroy(&boxt);
} else {
pixc = pixCreateTemplate(pixs);
pixr = pixClone(pixd);
}
pixSetAllArbitrary(pixc, color);
/* Set up the alpha channel */
pixg = pixConvertTo8(pixr, 0);
pixGammaTRC(pixg, pixg, gamma, minval, maxval);
pixSetRGBComponent(pixc, pixg, L_ALPHA_CHANNEL);
/* Blend and replace in pixd */
pixt = pixBlendWithGrayMask(pixr, pixc, NULL, 0, 0);
if (box) {
pixRasterop(pixd, x, y, w, h, PIX_SRC, pixt, 0, 0);
pixDestroy(&pixt);
} else {
pixTransferAllData(pixd, &pixt, 0, 0);
}
pixDestroy(&pixc);
pixDestroy(&pixr);
pixDestroy(&pixg);
return pixd;
}
/*---------------------------------------------------------------------*
* Multiplying by a specific color *
*---------------------------------------------------------------------*/
/*!
* pixMultiplyByColor()
*
* Input: pixd (can be NULL or pixs)
* pixs (32 bpp rgb)
* box (region for filtering; can be NULL))
* color (32 bit color in 0xrrggbb00 format)
* Return: pixd always
*
* Notes:
* (1) This filters all pixels in the specified region by
* multiplying each component by the input color.
* This leaves black invariant and transforms white to the
* input color.
* (2) If pixd == pixs, this is done in-place.
* (3) If box == NULL, this is performed on all of pixs.
*/
PIX *
pixMultiplyByColor(PIX *pixd,
PIX *pixs,
BOX *box,
l_uint32 color)
{
l_int32 i, j, bx, by, w, h, wpl;
l_int32 red, green, blue, rval, gval, bval, nrval, ngval, nbval;
l_float32 frval, fgval, fbval;
l_uint32 *data, *line;
PIX *pixt;
PROCNAME("pixMultiplyByColor");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs not 32 bpp", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd neither null nor pixs", procName, pixd);
if (!pixd)
pixd = pixCopy(NULL, pixs);
if (box) {
boxGetGeometry(box, &bx, &by, NULL, NULL);
pixt = pixClipRectangle(pixd, box, NULL);
} else {
pixt = pixClone(pixd);
}
/* Multiply each pixel in pixt by the color */
extractRGBValues(color, &red, &green, &blue);
frval = (1. / 255.) * red;
fgval = (1. / 255.) * green;
fbval = (1. / 255.) * blue;
data = pixGetData(pixt);
wpl = pixGetWpl(pixt);
pixGetDimensions(pixt, &w, &h, NULL);
for (i = 0; i < h; i++) {
line = data + i * wpl;
for (j = 0; j < w; j++) {
extractRGBValues(line[j], &rval, &gval, &bval);
nrval = (l_int32)(frval * rval + 0.5);
ngval = (l_int32)(fgval * gval + 0.5);
nbval = (l_int32)(fbval * bval + 0.5);
composeRGBPixel(nrval, ngval, nbval, line + j);
}
}
/* Replace */
if (box)
pixRasterop(pixd, bx, by, w, h, PIX_SRC, pixt, 0, 0);
pixDestroy(&pixt);
return pixd;
}
/*---------------------------------------------------------------------*
* Rendering with alpha blending over a uniform background *
*---------------------------------------------------------------------*/
/*!
* pixAlphaBlendUniform()
*
* Input: pixs (32 bpp rgba, with alpha)
* color (32 bit color in 0xrrggbb00 format)
* Return: pixd (32 bpp rgb: pixs blended over uniform color @color),
* a clone of pixs if no alpha, and null on error
*
* Notes:
* (1) This is a convenience function that renders 32 bpp RGBA images
* (with an alpha channel) over a uniform background of
* value @color. To render over a white background,
* use @color = 0xffffff00. The result is an RGB image.
* (2) If pixs does not have an alpha channel, it returns a clone
* of pixs.
*/
PIX *
pixAlphaBlendUniform(PIX *pixs,
l_uint32 color)
{
PIX *pixt, *pixd;
PROCNAME("pixAlphaBlendUniform");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs not 32 bpp", procName, NULL);
if (pixGetSpp(pixs) != 4) {
L_WARNING("no alpha channel; returning clone\n", procName);
return pixClone(pixs);
}
pixt = pixCreateTemplate(pixs);
pixSetAllArbitrary(pixt, color);
pixSetSpp(pixt, 3); /* not required */
pixd = pixBlendWithGrayMask(pixt, pixs, NULL, 0, 0);
pixDestroy(&pixt);
return pixd;
}
/*---------------------------------------------------------------------*
* Adding an alpha layer for blending *
*---------------------------------------------------------------------*/
/*!
* pixAddAlphaToBlend()
*
* Input: pixs (any depth)
* fract (fade fraction in the alpha component)
* invert (1 to photometrically invert pixs)
* Return: pixd (32 bpp with alpha), or null on error
*
* Notes:
* (1) This is a simple alpha layer generator, where typically white has
* maximum transparency and black has minimum.
* (2) If @invert == 1, generate the same alpha layer but invert
* the input image photometrically. This is useful for blending
* over dark images, where you want dark regions in pixs, such
* as text, to be lighter in the blended image.
* (3) The fade @fract gives the minimum transparency (i.e.,
* maximum opacity). A small fraction is useful for adding
* a watermark to an image.
* (4) If pixs has a colormap, it is removed to rgb.
* (5) If pixs already has an alpha layer, it is overwritten.
*/
PIX *
pixAddAlphaToBlend(PIX *pixs,
l_float32 fract,
l_int32 invert)
{
PIX *pixd, *pix1, *pix2;
PROCNAME("pixAddAlphaToBlend");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (fract < 0.0 || fract > 1.0)
return (PIX *)ERROR_PTR("invalid fract", procName, NULL);
/* Convert to 32 bpp */
if (pixGetColormap(pixs))
pix1 = pixRemoveColormap(pixs, REMOVE_CMAP_TO_FULL_COLOR);
else
pix1 = pixClone(pixs);
pixd = pixConvertTo32(pix1); /* new */
/* Use an inverted image if this will be blended with a dark image */
if (invert) pixInvert(pixd, pixd);
/* Generate alpha layer */
pix2 = pixConvertTo8(pix1, 0); /* new */
pixInvert(pix2, pix2);
pixMultConstantGray(pix2, fract);
pixSetRGBComponent(pixd, pix2, L_ALPHA_CHANNEL);
pixDestroy(&pix1);
pixDestroy(&pix2);
return pixd;
}
/*---------------------------------------------------------------------*
* Setting a transparent alpha component over a white background *
*---------------------------------------------------------------------*/
/*!
* pixSetAlphaOverWhite()
*
* Input: pixs (colormapped or 32 bpp rgb; no alpha)
* Return: pixd (new pix with meaningful alpha component),
* or null on error
*
* Notes:
* (1) The generated alpha component is transparent over white
* (background) pixels in pixs, and quickly grades to opaque
* away from the transparent parts. This is a cheap and
* dirty alpha generator. The 2 pixel gradation is useful
* to blur the boundary between the transparent region
* (that will render entirely from a backing image) and
* the remainder which renders from pixs.
* (2) All alpha component bits in pixs are overwritten.
*/
PIX *
pixSetAlphaOverWhite(PIX *pixs)
{
PIX *pixd, *pix1, *pix2, *pix3, *pix4;
PROCNAME("pixSetAlphaOverWhite");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!(pixGetDepth(pixs) == 32 || pixGetColormap(pixs)))
return (PIX *)ERROR_PTR("pixs not 32 bpp or cmapped", procName, NULL);
/* Remove colormap if it exists; otherwise copy */
pixd = pixRemoveColormapGeneral(pixs, REMOVE_CMAP_TO_FULL_COLOR, L_COPY);
/* Generate a 1 bpp image where a white pixel in pixd is 0.
* In the comments below, a "white" pixel refers to pixd.
* pix1 is rgb, pix2 is 8 bpp gray, pix3 is 1 bpp. */
pix1 = pixInvert(NULL, pixd); /* send white (255) to 0 for each sample */
pix2 = pixConvertRGBToGrayMinMax(pix1, L_CHOOSE_MAX); /* 0 if white */
pix3 = pixThresholdToBinary(pix2, 1); /* sets white pixels to 1 */
pixInvert(pix3, pix3); /* sets white pixels to 0 */
/* Generate the alpha component using the distance transform,
* which measures the distance to the nearest bg (0) pixel in pix3.
* After multiplying by 128, its value is 0 (transparent)
* over white pixels, and goes to opaque (255) two pixels away
* from the nearest white pixel. */
pix4 = pixDistanceFunction(pix3, 8, 8, L_BOUNDARY_FG);
pixMultConstantGray(pix4, 128.0);
pixSetRGBComponent(pixd, pix4, L_ALPHA_CHANNEL);
pixDestroy(&pix1);
pixDestroy(&pix2);
pixDestroy(&pix3);
pixDestroy(&pix4);
return pixd;
}