third-party/leptonica/src/coloring.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.
*====================================================================*/
/*
* coloring.c
*
* Coloring "gray" pixels
* PIX *pixColorGrayRegions()
* l_int32 pixColorGray()
* PIX *pixColorGrayMasked()
*
* Adjusting one or more colors to a target color
* PIX *pixSnapColor()
* PIX *pixSnapColorCmap()
*
* Piecewise linear color mapping based on a source/target pair
* PIX *pixLinearMapToTargetColor()
* l_int32 pixelLinearMapToTargetColor()
*
* Fractional shift of RGB towards black or white
* PIX *pixShiftByComponent()
* l_int32 pixelShiftByComponent()
* l_int32 pixelFractionalShift()
*
* There are several "coloring" functions in leptonica.
* You can find them in these files:
* coloring.c
* paintcmap.c
* pix2.c
* blend.c
* enhance.c
*
* They fall into the following categories:
*
* (1) Moving either the light or dark pixels toward a
* specified color. (pixColorGray, pixColorGrayMasked)
* (2) Forcing all pixels whose color is within some delta of a
* specified color to move to that color. (pixSnapColor)
* (3) Doing a piecewise linear color shift specified by a source
* and a target color. Each component shifts independently.
* (pixLinearMapToTargetColor)
* (4) Shifting all colors by a given fraction of their distance
* from 0 (if shifting down) or from 255 (if shifting up).
* This is useful for colorizing either the background or
* the foreground of a grayscale image. (pixShiftByComponent)
* (5) Shifting all colors by a component-dependent fraction of
* their distance from 0 (if shifting down) or from 255 (if
* shifting up). This is useful for modifying the color to
* compensate for color shifts in acquisition, for example
* (enhance.c: pixColorShiftRGB).
* (6) Repainting selected pixels. (paintcmap.c: pixSetSelectMaskedCmap)
* (7) Blending a fraction of a specific color with the existing RGB
* color. (pix2.c: pixBlendInRect())
* (8) Changing selected colors in a colormap.
* (paintcmap.c: pixSetSelectCmap, pixSetSelectMaskedCmap)
* (9) Shifting all the pixels towards black or white depending on
* the gray value of a second image. (blend.c: pixFadeWithGray)
* (10) Changing the hue, saturation or brightness, by changing the
* appropriate parameter in HSV color space by a fraction of
* the distance toward its end-point. For example, you can change
* the brightness by moving each pixel's v-parameter a specified
* fraction of the distance toward 0 (darkening) or toward 255
* (brightening). (enhance.c: pixModifySaturation,
* pixModifyHue, pixModifyBrightness)
*/
#include "allheaders.h"
/*---------------------------------------------------------------------*
* Coloring "gray" pixels *
*---------------------------------------------------------------------*/
/*!
* pixColorGrayRegions()
*
* Input: pixs (2, 4 or 8 bpp gray, rgb, or colormapped)
* boxa (of regions in which to apply color)
* type (L_PAINT_LIGHT, L_PAINT_DARK)
* thresh (average value below/above which pixel is unchanged)
* rval, gval, bval (new color to paint)
* Return: pixd, or null on error
*
* Notes:
* (1) This generates a new image, where some of the pixels in each
* box in the boxa are colorized. See pixColorGray() for usage
* with @type and @thresh. Note that @thresh is only used for
* rgb; it is ignored for colormapped images.
* (2) If the input image is colormapped, the new image will be 8 bpp
* colormapped if possible; otherwise, it will be converted
* to 32 bpp rgb. Only pixels that are strictly gray will be
* colorized.
* (3) If the input image is not colormapped, it is converted to rgb.
* A "gray" value for a pixel is determined by averaging the
* components, and the output rgb value is determined from this.
* (4) This can be used in conjunction with pixFindColorRegions() to
* add highlight color to a grayscale image.
*/
PIX *
pixColorGrayRegions(PIX *pixs,
BOXA *boxa,
l_int32 type,
l_int32 thresh,
l_int32 rval,
l_int32 gval,
l_int32 bval)
{
l_int32 i, n, ncolors, ngray;
BOX *box;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixColorGrayRegions");
if (!pixs || pixGetDepth(pixs) == 1)
return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
if (!boxa)
return (PIX *)ERROR_PTR("boxa not defined", procName, NULL);
if (type != L_PAINT_LIGHT && type != L_PAINT_DARK)
return (PIX *)ERROR_PTR("invalid type", procName, NULL);
/* If cmapped and there is room in an 8 bpp colormap for
* expansion, convert pixs to 8 bpp, and colorize. */
cmap = pixGetColormap(pixs);
if (cmap) {
ncolors = pixcmapGetCount(cmap);
pixcmapCountGrayColors(cmap, &ngray);
if (ncolors + ngray < 255) {
pixd = pixConvertTo8(pixs, 1); /* always new image */
pixColorGrayRegionsCmap(pixd, boxa, type, rval, gval, bval);
return pixd;
}
}
/* The output will be rgb. Make sure the thresholds are valid */
if (type == L_PAINT_LIGHT) { /* thresh should be low */
if (thresh >= 255)
return (PIX *)ERROR_PTR("thresh must be < 255", procName, NULL);
if (thresh > 127)
L_WARNING("threshold set very high\n", procName);
} else { /* type == L_PAINT_DARK; thresh should be high */
if (thresh <= 0)
return (PIX *)ERROR_PTR("thresh must be > 0", procName, NULL);
if (thresh < 128)
L_WARNING("threshold set very low\n", procName);
}
pixd = pixConvertTo32(pixs); /* always new image */
n = boxaGetCount(boxa);
for (i = 0; i < n; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
pixColorGray(pixd, box, type, thresh, rval, gval, bval);
boxDestroy(&box);
}
return pixd;
}
/*!
* pixColorGray()
*
* Input: pixs (8 bpp gray, rgb or colormapped image)
* box (<optional> region in which to apply color; can be NULL)
* type (L_PAINT_LIGHT, L_PAINT_DARK)
* thresh (average value below/above which pixel is unchanged)
* rval, gval, bval (new color to paint)
* Return: 0 if OK; 1 on error
*
* Notes:
* (1) This is an in-place operation; pixs is modified.
* If pixs is colormapped, the operation will add colors to the
* colormap. Otherwise, pixs will be converted to 32 bpp rgb if
* it is initially 8 bpp gray.
* (2) If type == L_PAINT_LIGHT, it colorizes non-black pixels,
* preserving antialiasing.
* If type == L_PAINT_DARK, it colorizes non-white pixels,
* preserving antialiasing.
* (3) If box is NULL, applies function to the entire image; otherwise,
* clips the operation to the intersection of the box and pix.
* (4) If colormapped, calls pixColorGrayCmap(), which applies the
* coloring algorithm only to pixels that are strictly gray.
* (5) For RGB, determines a "gray" value by averaging; then uses this
* value, plus the input rgb target, to generate the output
* pixel values.
* (6) thresh is only used for rgb; it is ignored for colormapped pix.
* If type == L_PAINT_LIGHT, use thresh = 0 if all pixels are to
* be colored (black pixels will be unaltered).
* In situations where there are a lot of black pixels,
* setting thresh > 0 will make the function considerably
* more efficient without affecting the final result.
* If type == L_PAINT_DARK, use thresh = 255 if all pixels
* are to be colored (white pixels will be unaltered).
* In situations where there are a lot of white pixels,
* setting thresh < 255 will make the function considerably
* more efficient without affecting the final result.
*/
l_int32
pixColorGray(PIX *pixs,
BOX *box,
l_int32 type,
l_int32 thresh,
l_int32 rval,
l_int32 gval,
l_int32 bval)
{
l_int32 i, j, w, h, d, wpl, x1, x2, y1, y2, bw, bh;
l_int32 nrval, ngval, nbval, aveval;
l_float32 factor;
l_uint32 val32;
l_uint32 *line, *data;
PIX *pixt;
PIXCMAP *cmap;
PROCNAME("pixColorGray");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (type != L_PAINT_LIGHT && type != L_PAINT_DARK)
return ERROR_INT("invalid type", procName, 1);
cmap = pixGetColormap(pixs);
pixGetDimensions(pixs, &w, &h, &d);
if (!cmap && d != 8 && d != 32)
return ERROR_INT("pixs not cmapped, 8 bpp or rgb", procName, 1);
if (cmap)
return pixColorGrayCmap(pixs, box, type, rval, gval, bval);
/* rgb or 8 bpp gray image; check the thresh */
if (type == L_PAINT_LIGHT) { /* thresh should be low */
if (thresh >= 255)
return ERROR_INT("thresh must be < 255; else this is a no-op",
procName, 1);
if (thresh > 127)
L_WARNING("threshold set very high\n", procName);
} else { /* type == L_PAINT_DARK; thresh should be high */
if (thresh <= 0)
return ERROR_INT("thresh must be > 0; else this is a no-op",
procName, 1);
if (thresh < 128)
L_WARNING("threshold set very low\n", procName);
}
/* In-place conversion to 32 bpp if necessary */
if (d == 8) {
pixt = pixConvertTo32(pixs);
pixTransferAllData(pixs, &pixt, 1, 0);
}
if (!box) {
x1 = y1 = 0;
x2 = w;
y2 = h;
} else {
boxGetGeometry(box, &x1, &y1, &bw, &bh);
x2 = x1 + bw - 1;
y2 = y1 + bh - 1;
}
data = pixGetData(pixs);
wpl = pixGetWpl(pixs);
factor = 1. / 255.;
for (i = y1; i <= y2; i++) {
if (i < 0 || i >= h)
continue;
line = data + i * wpl;
for (j = x1; j <= x2; j++) {
if (j < 0 || j >= w)
continue;
val32 = *(line + j);
aveval = ((val32 >> 24) + ((val32 >> 16) & 0xff) +
((val32 >> 8) & 0xff)) / 3;
if (type == L_PAINT_LIGHT) {
if (aveval < thresh) /* skip sufficiently dark pixels */
continue;
nrval = (l_int32)(rval * aveval * factor);
ngval = (l_int32)(gval * aveval * factor);
nbval = (l_int32)(bval * aveval * factor);
} else { /* type == L_PAINT_DARK */
if (aveval > thresh) /* skip sufficiently light pixels */
continue;
nrval = rval + (l_int32)((255. - rval) * aveval * factor);
ngval = gval + (l_int32)((255. - gval) * aveval * factor);
nbval = bval + (l_int32)((255. - bval) * aveval * factor);
}
composeRGBPixel(nrval, ngval, nbval, &val32);
*(line + j) = val32;
}
}
return 0;
}
/*!
* pixColorGrayMasked()
*
* Input: pixs (8 bpp gray, rgb or colormapped image)
* pixm (1 bpp mask, through which to apply color)
* type (L_PAINT_LIGHT, L_PAINT_DARK)
* thresh (average value below/above which pixel is unchanged)
* rval, gval, bval (new color to paint)
* Return: pixd (colorized), or null on error
*
* Notes:
* (1) This generates a new image, where some of the pixels under
* FG in the mask are colorized.
* (2) See pixColorGray() for usage with @type and @thresh. Note
* that @thresh is only used for rgb; it is ignored for
* colormapped images. In most cases, the mask will be over
* the darker parts and @type == L_PAINT_DARK.
* (3) If pixs is colormapped this calls pixColorMaskedCmap(),
* which adds colors to the colormap for pixd; it only adds
* colors corresponding to strictly gray colors in the colormap.
* Otherwise, if pixs is 8 bpp gray, pixd will be 32 bpp rgb.
* (4) If pixs is 32 bpp rgb, for each pixel a "gray" value is
* found by averaging. This average is then used with the
* input rgb target to generate the output pixel values.
* (5) This can be used in conjunction with pixFindColorRegions() to
* add highlight color to a grayscale image.
*/
PIX *
pixColorGrayMasked(PIX *pixs,
PIX *pixm,
l_int32 type,
l_int32 thresh,
l_int32 rval,
l_int32 gval,
l_int32 bval)
{
l_int32 i, j, w, h, d, wm, hm, wmin, hmin, wpl, wplm;
l_int32 nrval, ngval, nbval, aveval;
l_float32 factor;
l_uint32 val32;
l_uint32 *line, *data, *linem, *datam;
PIX *pixd;
PIXCMAP *cmap;
PROCNAME("pixColorGrayMasked");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!pixm || pixGetDepth(pixm) != 1)
return (PIX *)ERROR_PTR("pixm undefined or not 1 bpp", procName, NULL);
if (type != L_PAINT_LIGHT && type != L_PAINT_DARK)
return (PIX *)ERROR_PTR("invalid type", procName, NULL);
cmap = pixGetColormap(pixs);
pixGetDimensions(pixs, &w, &h, &d);
if (!cmap && d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not cmapped, 8 bpp gray or 32 bpp",
procName, NULL);
if (cmap) {
pixd = pixCopy(NULL, pixs);
pixColorGrayMaskedCmap(pixd, pixm, type, rval, gval, bval);
return pixd;
}
/* rgb or 8 bpp gray image; check the thresh */
if (type == L_PAINT_LIGHT) { /* thresh should be low */
if (thresh >= 255)
return (PIX *)ERROR_PTR(
"thresh must be < 255; else this is a no-op", procName, NULL);
if (thresh > 127)
L_WARNING("threshold set very high\n", procName);
} else { /* type == L_PAINT_DARK; thresh should be high */
if (thresh <= 0)
return (PIX *)ERROR_PTR(
"thresh must be > 0; else this is a no-op", procName, NULL);
if (thresh < 128)
L_WARNING("threshold set very low\n", procName);
}
pixGetDimensions(pixm, &wm, &hm, NULL);
if (wm != w)
L_WARNING("wm = %d differs from w = %d\n", procName, wm, w);
if (hm != h)
L_WARNING("hm = %d differs from h = %d\n", procName, hm, h);
wmin = L_MIN(w, wm);
hmin = L_MIN(h, hm);
if (d == 8)
pixd = pixConvertTo32(pixs);
else
pixd = pixCopy(NULL, pixs);
data = pixGetData(pixd);
wpl = pixGetWpl(pixd);
datam = pixGetData(pixm);
wplm = pixGetWpl(pixm);
factor = 1. / 255.;
for (i = 0; i < hmin; i++) {
line = data + i * wpl;
linem = datam + i * wplm;
for (j = 0; j < wmin; j++) {
if (GET_DATA_BIT(linem, j) == 0)
continue;
val32 = *(line + j);
aveval = ((val32 >> 24) + ((val32 >> 16) & 0xff) +
((val32 >> 8) & 0xff)) / 3;
if (type == L_PAINT_LIGHT) {
if (aveval < thresh) /* skip sufficiently dark pixels */
continue;
nrval = (l_int32)(rval * aveval * factor);
ngval = (l_int32)(gval * aveval * factor);
nbval = (l_int32)(bval * aveval * factor);
} else { /* type == L_PAINT_DARK */
if (aveval > thresh) /* skip sufficiently light pixels */
continue;
nrval = rval + (l_int32)((255. - rval) * aveval * factor);
ngval = gval + (l_int32)((255. - gval) * aveval * factor);
nbval = bval + (l_int32)((255. - bval) * aveval * factor);
}
composeRGBPixel(nrval, ngval, nbval, &val32);
*(line + j) = val32;
}
}
return pixd;
}
/*------------------------------------------------------------------*
* Adjusting one or more colors to a target color *
*------------------------------------------------------------------*/
/*!
* pixSnapColor()
*
* Input: pixd (<optional>; either NULL or equal to pixs for in-place)
* pixs (colormapped or 8 bpp gray or 32 bpp rgb)
* srcval (color center to be selected for change: 0xrrggbb00)
* dstval (target color for pixels: 0xrrggbb00)
* diff (max absolute difference, applied to all components)
* Return: pixd (with all pixels within diff of pixval set to pixval),
* or pixd on error
*
* Notes:
* (1) For inplace operation, call it this way:
* pixSnapColor(pixs, pixs, ... )
* (2) For generating a new pixd:
* pixd = pixSnapColor(NULL, pixs, ...)
* (3) If pixs has a colormap, it is handled by pixSnapColorCmap().
* (4) All pixels within 'diff' of 'srcval', componentwise,
* will be changed to 'dstval'.
*/
PIX *
pixSnapColor(PIX *pixd,
PIX *pixs,
l_uint32 srcval,
l_uint32 dstval,
l_int32 diff)
{
l_int32 val, sval, dval;
l_int32 rval, gval, bval, rsval, gsval, bsval;
l_int32 i, j, w, h, d, wpl;
l_uint32 pixel;
l_uint32 *line, *data;
PROCNAME("pixSnapColor");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd not null or == pixs", procName, pixd);
if (pixGetColormap(pixs))
return pixSnapColorCmap(pixd, pixs, srcval, dstval, diff);
/* pixs does not have a colormap; it must be 8 bpp gray or
* 32 bpp rgb. */
if (pixGetDepth(pixs) < 8)
return (PIX *)ERROR_PTR("pixs is < 8 bpp", procName, pixd);
/* Do the work on pixd */
if (!pixd)
pixd = pixCopy(NULL, pixs);
pixGetDimensions(pixd, &w, &h, &d);
data = pixGetData(pixd);
wpl = pixGetWpl(pixd);
if (d == 8) {
sval = srcval & 0xff;
dval = dstval & 0xff;
for (i = 0; i < h; i++) {
line = data + i * wpl;
for (j = 0; j < w; j++) {
val = GET_DATA_BYTE(line, j);
if (L_ABS(val - sval) <= diff)
SET_DATA_BYTE(line, j, dval);
}
}
} else { /* d == 32 */
extractRGBValues(srcval, &rsval, &gsval, &bsval);
for (i = 0; i < h; i++) {
line = data + i * wpl;
for (j = 0; j < w; j++) {
pixel = *(line + j);
extractRGBValues(pixel, &rval, &gval, &bval);
if ((L_ABS(rval - rsval) <= diff) &&
(L_ABS(gval - gsval) <= diff) &&
(L_ABS(bval - bsval) <= diff))
*(line + j) = dstval; /* replace */
}
}
}
return pixd;
}
/*!
* pixSnapColorCmap()
*
* Input: pixd (<optional>; either NULL or equal to pixs for in-place)
* pixs (colormapped)
* srcval (color center to be selected for change: 0xrrggbb00)
* dstval (target color for pixels: 0xrrggbb00)
* diff (max absolute difference, applied to all components)
* Return: pixd (with all pixels within diff of srcval set to dstval),
* or pixd on error
*
* Notes:
* (1) For inplace operation, call it this way:
* pixSnapCcmap(pixs, pixs, ... )
* (2) For generating a new pixd:
* pixd = pixSnapCmap(NULL, pixs, ...)
* (3) pixs must have a colormap.
* (4) All colors within 'diff' of 'srcval', componentwise,
* will be changed to 'dstval'.
*/
PIX *
pixSnapColorCmap(PIX *pixd,
PIX *pixs,
l_uint32 srcval,
l_uint32 dstval,
l_int32 diff)
{
l_int32 i, ncolors, index, found;
l_int32 rval, gval, bval, rsval, gsval, bsval, rdval, gdval, bdval;
l_int32 *tab;
PIX *pixm;
PIXCMAP *cmap;
PROCNAME("pixSnapColorCmap");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (!pixGetColormap(pixs))
return (PIX *)ERROR_PTR("cmap not found", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd not null or == pixs", procName, pixd);
if (!pixd)
pixd = pixCopy(NULL, pixs);
/* If no free colors, look for one close to the target
* that can be commandeered. */
cmap = pixGetColormap(pixd);
ncolors = pixcmapGetCount(cmap);
extractRGBValues(srcval, &rsval, &gsval, &bsval);
extractRGBValues(dstval, &rdval, &gdval, &bdval);
found = FALSE;
if (pixcmapGetFreeCount(cmap) == 0) {
for (i = 0; i < ncolors; i++) {
pixcmapGetColor(cmap, i, &rval, &gval, &bval);
if ((L_ABS(rval - rsval) <= diff) &&
(L_ABS(gval - gsval) <= diff) &&
(L_ABS(bval - bsval) <= diff)) {
index = i;
pixcmapResetColor(cmap, index, rdval, gdval, bdval);
found = TRUE;
break;
}
}
} else { /* just add the new color */
pixcmapAddColor(cmap, rdval, gdval, bdval);
ncolors = pixcmapGetCount(cmap);
index = ncolors - 1; /* index of new destination color */
found = TRUE;
}
if (!found) {
L_INFO("nothing to do\n", procName);
return pixd;
}
/* For each color in cmap that is close enough to srcval,
* set the tab value to 1. Then generate a 1 bpp mask with
* fg pixels for every pixel in pixd that is close enough
* to srcval (i.e., has value 1 in tab). */
if ((tab = (l_int32 *)CALLOC(256, sizeof(l_int32))) == NULL)
return (PIX *)ERROR_PTR("tab not made", procName, pixd);
for (i = 0; i < ncolors; i++) {
pixcmapGetColor(cmap, i, &rval, &gval, &bval);
if ((L_ABS(rval - rsval) <= diff) &&
(L_ABS(gval - gsval) <= diff) &&
(L_ABS(bval - bsval) <= diff))
tab[i] = 1;
}
pixm = pixMakeMaskFromLUT(pixd, tab);
FREE(tab);
/* Use the binary mask to set all selected pixels to
* the dest color index. */
pixSetMasked(pixd, pixm, dstval);
pixDestroy(&pixm);
/* Remove all unused colors from the colormap. */
pixRemoveUnusedColors(pixd);
return pixd;
}
/*---------------------------------------------------------------------*
* Piecewise linear color mapping based on a source/target pair *
*---------------------------------------------------------------------*/
/*!
* pixLinearMapToTargetColor()
*
* Input: pixd (<optional>; either NULL or equal to pixs for in-place)
* pixs (32 bpp rgb)
* srcval (source color: 0xrrggbb00)
* dstval (target color: 0xrrggbb00)
* Return: pixd (with all pixels mapped based on the srcval/destval
* mapping), or pixd on error
*
* Notes:
* (1) For each component (r, b, g) separately, this does a piecewise
* linear mapping of the colors in pixs to colors in pixd.
* If rs and rd are the red src and dest components in @srcval and
* @dstval, then the range [0 ... rs] in pixs is mapped to
* [0 ... rd] in pixd. Likewise, the range [rs ... 255] in pixs
* is mapped to [rd ... 255] in pixd. And similarly for green
* and blue.
* (2) The mapping will in general change the hue of the pixels.
* However, if the src and dst targets are related by
* a transformation given by pixelFractionalShift(), the hue
* is invariant.
* (3) For inplace operation, call it this way:
* pixLinearMapToTargetColor(pixs, pixs, ... )
* (4) For generating a new pixd:
* pixd = pixLinearMapToTargetColor(NULL, pixs, ...)
*/
PIX *
pixLinearMapToTargetColor(PIX *pixd,
PIX *pixs,
l_uint32 srcval,
l_uint32 dstval)
{
l_int32 i, j, w, h, wpl;
l_int32 rval, gval, bval, rsval, gsval, bsval, rdval, gdval, bdval;
l_int32 *rtab, *gtab, *btab;
l_uint32 pixel;
l_uint32 *line, *data;
PROCNAME("pixLinearMapToTargetColor");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd not null or == pixs", procName, pixd);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs is not 32 bpp", procName, pixd);
/* Do the work on pixd */
if (!pixd)
pixd = pixCopy(NULL, pixs);
extractRGBValues(srcval, &rsval, &gsval, &bsval);
extractRGBValues(dstval, &rdval, &gdval, &bdval);
rsval = L_MIN(254, L_MAX(1, rsval));
gsval = L_MIN(254, L_MAX(1, gsval));
bsval = L_MIN(254, L_MAX(1, bsval));
rtab = (l_int32 *)CALLOC(256, sizeof(l_int32));
gtab = (l_int32 *)CALLOC(256, sizeof(l_int32));
btab = (l_int32 *)CALLOC(256, sizeof(l_int32));
for (i = 0; i < 256; i++) {
if (i <= rsval)
rtab[i] = (i * rdval) / rsval;
else
rtab[i] = rdval + ((255 - rdval) * (i - rsval)) / (255 - rsval);
if (i <= gsval)
gtab[i] = (i * gdval) / gsval;
else
gtab[i] = gdval + ((255 - gdval) * (i - gsval)) / (255 - gsval);
if (i <= bsval)
btab[i] = (i * bdval) / bsval;
else
btab[i] = bdval + ((255 - bdval) * (i - bsval)) / (255 - bsval);
}
pixGetDimensions(pixd, &w, &h, NULL);
data = pixGetData(pixd);
wpl = pixGetWpl(pixd);
for (i = 0; i < h; i++) {
line = data + i * wpl;
for (j = 0; j < w; j++) {
pixel = line[j];
extractRGBValues(pixel, &rval, &gval, &bval);
composeRGBPixel(rtab[rval], gtab[gval], btab[bval], &pixel);
line[j] = pixel;
}
}
FREE(rtab);
FREE(gtab);
FREE(btab);
return pixd;
}
/*!
* pixelLinearMapToTargetColor()
*
* Input: scolor (rgb source color: 0xrrggbb00)
* srcmap (source mapping color: 0xrrggbb00)
* dstmap (target mapping color: 0xrrggbb00)
* &pdcolor (<return> rgb dest color: 0xrrggbb00)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This does this does a piecewise linear mapping of each
* component of @scolor to @dcolor, based on the relation
* between the components of @srcmap and @dstmap. It is the
* same transformation, performed on a single color, as mapped
* on every pixel in a pix by pixLinearMapToTargetColor().
* (2) For each component, if the sval is larger than the smap,
* the dval will be pushed up from dmap towards white.
* Otherwise, dval will be pushed down from dmap towards black.
* This is because you can visualize the transformation as
* a linear stretching where smap moves to dmap, and everything
* else follows linearly with 0 and 255 fixed.
* (3) The mapping will in general change the hue of @scolor.
* However, if the @srcmap and @dstmap targets are related by
* a transformation given by pixelFractionalShift(), the hue
* will be invariant.
*/
l_int32
pixelLinearMapToTargetColor(l_uint32 scolor,
l_uint32 srcmap,
l_uint32 dstmap,
l_uint32 *pdcolor)
{
l_int32 srval, sgval, sbval, drval, dgval, dbval;
l_int32 srmap, sgmap, sbmap, drmap, dgmap, dbmap;
PROCNAME("pixelLinearMapToTargetColor");
if (!pdcolor)
return ERROR_INT("&dcolor not defined", procName, 1);
*pdcolor = 0;
extractRGBValues(scolor, &srval, &sgval, &sbval);
extractRGBValues(srcmap, &srmap, &sgmap, &sbmap);
extractRGBValues(dstmap, &drmap, &dgmap, &dbmap);
srmap = L_MIN(254, L_MAX(1, srmap));
sgmap = L_MIN(254, L_MAX(1, sgmap));
sbmap = L_MIN(254, L_MAX(1, sbmap));
if (srval <= srmap)
drval = (srval * drmap) / srmap;
else
drval = drmap + ((255 - drmap) * (srval - srmap)) / (255 - srmap);
if (sgval <= sgmap)
dgval = (sgval * dgmap) / sgmap;
else
dgval = dgmap + ((255 - dgmap) * (sgval - sgmap)) / (255 - sgmap);
if (sbval <= sbmap)
dbval = (sbval * dbmap) / sbmap;
else
dbval = dbmap + ((255 - dbmap) * (sbval - sbmap)) / (255 - sbmap);
composeRGBPixel(drval, dgval, dbval, pdcolor);
return 0;
}
/*------------------------------------------------------------------*
* Fractional shift of RGB towards black or white *
*------------------------------------------------------------------*/
/*!
* pixShiftByComponent()
*
* Input: pixd (<optional>; either NULL or equal to pixs for in-place)
* pixs (32 bpp rgb)
* srcval (source color: 0xrrggbb00)
* dstval (target color: 0xrrggbb00)
* Return: pixd (with all pixels mapped based on the srcval/destval
* mapping), or pixd on error
*
* Notes:
* (1) For each component (r, b, g) separately, this does a linear
* mapping of the colors in pixs to colors in pixd.
* Let rs and rd be the red src and dest components in @srcval and
* @dstval, and rval is the red component of the src pixel.
* Then for all pixels in pixs, the mapping for the red
* component from pixs to pixd is:
* if (rd <= rs) (shift toward black)
* rval --> (rd/rs) * rval
* if (rd > rs) (shift toward white)
* (255 - rval) --> ((255 - rs)/(255 - rd)) * (255 - rval)
* Thus if rd <= rs, the red component of all pixels is
* mapped by the same fraction toward white, and if rd > rs,
* they are mapped by the same fraction toward black.
* This is essentially a different linear TRC (gamma = 1)
* for each component. The source and target color inputs are
* just used to generate the three fractions.
* (2) Note that this mapping differs from that in
* pixLinearMapToTargetColor(), which maps rs --> rd and does
* a piecewise stretching in between.
* (3) For inplace operation, call it this way:
* pixFractionalShiftByComponent(pixs, pixs, ... )
* (4) For generating a new pixd:
* pixd = pixLinearMapToTargetColor(NULL, pixs, ...)
* (5) A simple application is to color a grayscale image.
* A light background can be colored using srcval = 0xffffff00
* and picking a target background color for dstval.
* A dark foreground can be colored by using srcval = 0x0
* and choosing a target foreground color for dstval.
*/
PIX *
pixShiftByComponent(PIX *pixd,
PIX *pixs,
l_uint32 srcval,
l_uint32 dstval)
{
l_int32 i, j, w, h, wpl;
l_int32 rval, gval, bval, rsval, gsval, bsval, rdval, gdval, bdval;
l_int32 *rtab, *gtab, *btab;
l_uint32 pixel;
l_uint32 *line, *data;
PIXCMAP *cmap;
PROCNAME("pixShiftByComponent");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (pixd && (pixd != pixs))
return (PIX *)ERROR_PTR("pixd not null or == pixs", procName, pixd);
if (pixGetDepth(pixs) != 32 && !pixGetColormap(pixs))
return (PIX *)ERROR_PTR("pixs not cmapped or 32 bpp", procName, pixd);
/* Do the work on pixd */
if (!pixd)
pixd = pixCopy(NULL, pixs);
/* If colormapped, just modify it */
if ((cmap = pixGetColormap(pixd)) != NULL) {
pixcmapShiftByComponent(cmap, srcval, dstval);
return pixd;
}
extractRGBValues(srcval, &rsval, &gsval, &bsval);
extractRGBValues(dstval, &rdval, &gdval, &bdval);
rtab = (l_int32 *)CALLOC(256, sizeof(l_int32));
gtab = (l_int32 *)CALLOC(256, sizeof(l_int32));
btab = (l_int32 *)CALLOC(256, sizeof(l_int32));
for (i = 0; i < 256; i++) {
if (rdval == rsval)
rtab[i] = i;
else if (rdval < rsval)
rtab[i] = (i * rdval) / rsval;
else
rtab[i] = 255 - (255 - rdval) * (255 - i) / (255 - rsval);
if (gdval == gsval)
gtab[i] = i;
else if (gdval < gsval)
gtab[i] = (i * gdval) / gsval;
else
gtab[i] = 255 - (255 - gdval) * (255 - i) / (255 - gsval);
if (bdval == bsval)
btab[i] = i;
else if (bdval < bsval)
btab[i] = (i * bdval) / bsval;
else
btab[i] = 255 - (255 - bdval) * (255 - i) / (255 - bsval);
}
pixGetDimensions(pixd, &w, &h, NULL);
data = pixGetData(pixd);
wpl = pixGetWpl(pixd);
for (i = 0; i < h; i++) {
line = data + i * wpl;
for (j = 0; j < w; j++) {
pixel = line[j];
extractRGBValues(pixel, &rval, &gval, &bval);
composeRGBPixel(rtab[rval], gtab[gval], btab[bval], &pixel);
line[j] = pixel;
}
}
FREE(rtab);
FREE(gtab);
FREE(btab);
return pixd;
}
/*!
* pixelShiftByComponent()
*
* Input: rval, gval, bval
* srcval (source color: 0xrrggbb00)
* dstval (target color: 0xrrggbb00)
* &ppixel (<return> rgb value)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is a linear transformation that gives the same result
* on a single pixel as pixShiftByComponent() gives
* on a pix. Each component is handled separately. If
* the dest component is larger than the src, then the
* component is pushed toward 255 by the same fraction as
* the src --> dest shift.
*/
l_int32
pixelShiftByComponent(l_int32 rval,
l_int32 gval,
l_int32 bval,
l_uint32 srcval,
l_uint32 dstval,
l_uint32 *ppixel)
{
l_int32 rsval, rdval, gsval, gdval, bsval, bdval, rs, gs, bs;
PROCNAME("pixelShiftByComponent");
if (!ppixel)
return ERROR_INT("&pixel defined", procName, 1);
extractRGBValues(srcval, &rsval, &gsval, &bsval);
extractRGBValues(dstval, &rdval, &gdval, &bdval);
if (rdval == rsval)
rs = rval;
else if (rdval < rsval)
rs = (rval * rdval) / rsval;
else
rs = 255 - (255 - rdval) * (255 - rval) / (255 - rsval);
if (gdval == gsval)
gs = gval;
else if (gdval < gsval)
gs = (gval * gdval) / gsval;
else
gs = 255 - (255 - gdval) * (255 - gval) / (255 - gsval);
if (bdval == bsval)
bs = bval;
else if (bdval < bsval)
bs = (bval * bdval) / bsval;
else
bs = 255 - (255 - bdval) * (255 - bval) / (255 - bsval);
composeRGBPixel(rs, gs, bs, ppixel);
return 0;
}
/*!
* pixelFractionalShift()
*
* Input: rval, gval, bval
* fraction (negative toward black; positive toward white)
* &ppixel (<return> rgb value)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This transformation leaves the hue invariant, while changing
* the saturation and intensity. It can be used for that
* purpose in pixLinearMapToTargetColor().
* (2) @fraction is in the range [-1 .... +1]. If @fraction < 0,
* saturation is increased and brightness is reduced. The
* opposite results if @fraction > 0. If @fraction == -1,
* the resulting pixel is black; @fraction == 1 results in white.
*/
l_int32
pixelFractionalShift(l_int32 rval,
l_int32 gval,
l_int32 bval,
l_float32 fraction,
l_uint32 *ppixel)
{
l_int32 nrval, ngval, nbval;
PROCNAME("pixelFractionalShift");
if (!ppixel)
return ERROR_INT("&pixel defined", procName, 1);
if (fraction < -1.0 || fraction > 1.0)
return ERROR_INT("fraction not in [-1 ... +1]", procName, 1);
nrval = (fraction < 0) ? (l_int32)((1.0 + fraction) * rval + 0.5) :
rval + (l_int32)(fraction * (255 - rval) + 0.5);
ngval = (fraction < 0) ? (l_int32)((1.0 + fraction) * gval + 0.5) :
gval + (l_int32)(fraction * (255 - gval) + 0.5);
nbval = (fraction < 0) ? (l_int32)((1.0 + fraction) * bval + 0.5) :
bval + (l_int32)(fraction * (255 - bval) + 0.5);
composeRGBPixel(nrval, ngval, nbval, ppixel);
return 0;
}