third-party/leptonica/src/warper.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.
*====================================================================*/
/*
* warper.c
*
* High-level captcha interface
* PIX *pixSimpleCaptcha()
*
* Random sinusoidal warping
* PIX *pixRandomHarmonicWarp()
*
* Helper functions
* static l_float64 *generateRandomNumberArray()
* static l_int32 applyWarpTransform()
*
* Version using a LUT for sin
* PIX *pixRandomHarmonicWarpLUT()
* static l_int32 applyWarpTransformLUT()
* static l_int32 makeSinLUT()
* static l_float32 getSinFromLUT()
*
* Stereoscopic warping
* PIX *pixWarpStereoscopic()
*
* Linear and quadratic horizontal stretching
* PIX *pixStretchHorizontal()
* PIX *pixStretchHorizontalSampled()
* PIX *pixStretchHorizontalLI()
*
* Quadratic vertical shear
* PIX *pixQuadraticVShear()
* PIX *pixQuadraticVShearSampled()
* PIX *pixQuadraticVShearLI()
*
* Stereo from a pair of images
* PIX *pixStereoFromPair()
*/
#include <math.h>
#include "allheaders.h"
static l_float64 *generateRandomNumberArray(l_int32 size);
static l_int32 applyWarpTransform(l_float32 xmag, l_float32 ymag,
l_float32 xfreq, l_float32 yfreq,
l_float64 *randa, l_int32 nx, l_int32 ny,
l_int32 xp, l_int32 yp,
l_float32 *px, l_float32 *py);
#define USE_SIN_TABLE 0
/* Suggested input to pixStereoFromPair(). These are weighting
* factors for input to the red channel from the left image. */
static const l_float32 L_DEFAULT_RED_WEIGHT = 0.0;
static const l_float32 L_DEFAULT_GREEN_WEIGHT = 0.7;
static const l_float32 L_DEFAULT_BLUE_WEIGHT = 0.3;
/*----------------------------------------------------------------------*
* High-level example captcha interface *
*----------------------------------------------------------------------*/
/*!
* pixSimpleCaptcha()
*
* Input: pixs (8 bpp; no colormap)
* border (added white pixels on each side)
* nterms (number of x and y harmonic terms)
* seed (of random number generator)
* color (for colorizing; in 0xrrggbb00 format; use 0 for black)
* cmapflag (1 for colormap output; 0 for rgb)
* Return: pixd (8 bpp cmap or 32 bpp rgb), or null on error
*
* Notes:
* (1) This uses typical default values for generating captchas.
* The magnitudes of the harmonic warp are typically to be
* smaller when more terms are used, even though the phases
* are random. See, for example, prog/warptest.c.
*/
PIX *
pixSimpleCaptcha(PIX *pixs,
l_int32 border,
l_int32 nterms,
l_uint32 seed,
l_uint32 color,
l_int32 cmapflag)
{
l_int32 k;
l_float32 xmag[] = {7.0, 5.0, 4.0, 3.0};
l_float32 ymag[] = {10.0, 8.0, 6.0, 5.0};
l_float32 xfreq[] = {0.12, 0.10, 0.10, 0.11};
l_float32 yfreq[] = {0.15, 0.13, 0.13, 0.11};
PIX *pixg, *pixgb, *pixw, *pixd;
PROCNAME("pixSimpleCaptcha");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (nterms < 1 || nterms > 4)
return (PIX *)ERROR_PTR("nterms must be in {1,2,3,4}", procName, NULL);
k = nterms - 1;
pixg = pixConvertTo8(pixs, 0);
pixgb = pixAddBorder(pixg, border, 255);
pixw = pixRandomHarmonicWarp(pixgb, xmag[k], ymag[k], xfreq[k], yfreq[k],
nterms, nterms, seed, 255);
pixd = pixColorizeGray(pixw, color, cmapflag);
pixDestroy(&pixg);
pixDestroy(&pixgb);
pixDestroy(&pixw);
return pixd;
}
/*----------------------------------------------------------------------*
* Random sinusoidal warping *
*----------------------------------------------------------------------*/
/*!
* pixRandomHarmonicWarp()
*
* Input: pixs (8 bpp; no colormap)
* xmag, ymag (maximum magnitude of x and y distortion)
* xfreq, yfreq (maximum magnitude of x and y frequency)
* nx, ny (number of x and y harmonic terms)
* seed (of random number generator)
* grayval (color brought in from the outside;
* 0 for black, 255 for white)
* Return: pixd (8 bpp; no colormap), or null on error
*
* Notes:
* (1) To generate the warped image p(x',y'), set up the transforms
* that are in getWarpTransform(). For each (x',y') in the
* dest, the warp function computes the originating location
* (x, y) in the src. The differences (x - x') and (y - y')
* are given as a sum of products of sinusoidal terms. Each
* term is multiplied by a maximum amplitude (in pixels), and the
* angle is determined by a frequency and phase, and depends
* on the (x', y') value of the dest. Random numbers with
* a variable input seed are used to allow the warping to be
* unpredictable. A linear interpolation is used to find
* the value for the source at (x, y); this value is written
* into the dest.
* (2) This can be used to generate 'captcha's, which are somewhat
* randomly distorted images of text. A typical set of parameters
* for a captcha are:
* xmag = 4.0 ymag = 6.0
* xfreq = 0.10 yfreq = 0.13
* nx = 3 ny = 3
* Other examples can be found in prog/warptest.c.
*/
PIX *
pixRandomHarmonicWarp(PIX *pixs,
l_float32 xmag,
l_float32 ymag,
l_float32 xfreq,
l_float32 yfreq,
l_int32 nx,
l_int32 ny,
l_uint32 seed,
l_int32 grayval)
{
l_int32 w, h, d, i, j, wpls, wpld, val;
l_uint32 *datas, *datad, *lined;
l_float32 x, y;
l_float64 *randa;
PIX *pixd;
PROCNAME("pixRandomHarmonicWarp");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 8)
return (PIX *)ERROR_PTR("pixs not 8 bpp", procName, NULL);
/* Compute filter output at each location. We iterate over
* the destination pixels. For each dest pixel, use the
* warp function to compute the four source pixels that
* contribute, at the location (x, y). Each source pixel
* is divided into 16 x 16 subpixels to get an approximate value. */
srand(seed);
randa = generateRandomNumberArray(5 * (nx + ny));
pixd = pixCreateTemplate(pixs);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
for (i = 0; i < h; i++) {
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
applyWarpTransform(xmag, ymag, xfreq, yfreq, randa, nx, ny,
j, i, &x, &y);
linearInterpolatePixelGray(datas, wpls, w, h, x, y, grayval, &val);
SET_DATA_BYTE(lined, j, val);
}
}
FREE(randa);
return pixd;
}
/*----------------------------------------------------------------------*
* Static helper functions *
*----------------------------------------------------------------------*/
static l_float64 *
generateRandomNumberArray(l_int32 size)
{
l_int32 i;
l_float64 *randa;
PROCNAME("generateRandomNumberArray");
if ((randa = (l_float64 *)CALLOC(size, sizeof(l_float64))) == NULL)
return (l_float64 *)ERROR_PTR("calloc fail for randa", procName, NULL);
/* Return random values between 0.5 and 1.0 */
for (i = 0; i < size; i++)
randa[i] = 0.5 * (1.0 + (l_float64)rand() / (l_float64)RAND_MAX);
return randa;
}
/*!
* applyWarpTransform()
*
* Notes:
* (1) Uses the internal sin function.
*/
static l_int32
applyWarpTransform(l_float32 xmag,
l_float32 ymag,
l_float32 xfreq,
l_float32 yfreq,
l_float64 *randa,
l_int32 nx,
l_int32 ny,
l_int32 xp,
l_int32 yp,
l_float32 *px,
l_float32 *py)
{
l_int32 i;
l_float64 twopi, x, y, anglex, angley;
twopi = 6.283185;
for (i = 0, x = xp; i < nx; i++) {
anglex = xfreq * randa[3 * i + 1] * xp + twopi * randa[3 * i + 2];
angley = yfreq * randa[3 * i + 3] * yp + twopi * randa[3 * i + 4];
x += xmag * randa[3 * i] * sin(anglex) * sin(angley);
}
for (i = nx, y = yp; i < nx + ny; i++) {
angley = yfreq * randa[3 * i + 1] * yp + twopi * randa[3 * i + 2];
anglex = xfreq * randa[3 * i + 3] * xp + twopi * randa[3 * i + 4];
y += ymag * randa[3 * i] * sin(angley) * sin(anglex);
}
*px = (l_float32)x;
*py = (l_float32)y;
return 0;
}
#if USE_SIN_TABLE
/*----------------------------------------------------------------------*
* Version using a LUT for sin *
*----------------------------------------------------------------------*/
static l_int32 applyWarpTransformLUT(l_float32 xmag, l_float32 ymag,
l_float32 xfreq, l_float32 yfreq,
l_float64 *randa, l_int32 nx, l_int32 ny,
l_int32 xp, l_int32 yp, l_float32 *lut,
l_int32 npts, l_float32 *px, l_float32 *py);
static l_int32 makeSinLUT(l_int32 npts, NUMA **pna);
static l_float32 getSinFromLUT(l_float32 *tab, l_int32 npts,
l_float32 radang);
/*!
* pixRandomHarmonicWarpLUT()
*
* Input: pixs (8 bpp; no colormap)
* xmag, ymag (maximum magnitude of x and y distortion)
* xfreq, yfreq (maximum magnitude of x and y frequency)
* nx, ny (number of x and y harmonic terms)
* seed (of random number generator)
* grayval (color brought in from the outside;
* 0 for black, 255 for white)
* Return: pixd (8 bpp; no colormap), or null on error
*
* Notes:
* (1) See notes and inline comments in pixRandomHarmonicWarp().
* This version uses a LUT for the sin function. It is not
* appreciably faster than using the built-in sin function,
* and is here for comparison only.
*/
PIX *
pixRandomHarmonicWarpLUT(PIX *pixs,
l_float32 xmag,
l_float32 ymag,
l_float32 xfreq,
l_float32 yfreq,
l_int32 nx,
l_int32 ny,
l_uint32 seed,
l_int32 grayval)
{
l_int32 w, h, d, i, j, wpls, wpld, val, npts;
l_uint32 *datas, *datad, *lined;
l_float32 x, y;
l_float32 *lut;
l_float64 *randa;
NUMA *na;
PIX *pixd;
PROCNAME("pixRandomHarmonicWarp");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 8)
return (PIX *)ERROR_PTR("pixs not 8 bpp", procName, NULL);
/* Compute filter output at each location. We iterate over
* the destination pixels. For each dest pixel, use the
* warp function to compute the four source pixels that
* contribute, at the location (x, y). Each source pixel
* is divided into 16 x 16 subpixels to get an approximate value. */
srand(seed);
randa = generateRandomNumberArray(5 * (nx + ny));
pixd = pixCreateTemplate(pixs);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
npts = 100;
makeSinLUT(npts, &na);
lut = numaGetFArray(na, L_NOCOPY);
for (i = 0; i < h; i++) {
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
applyWarpTransformLUT(xmag, ymag, xfreq, yfreq, randa, nx, ny,
j, i, lut, npts, &x, &y);
linearInterpolatePixelGray(datas, wpls, w, h, x, y, grayval, &val);
SET_DATA_BYTE(lined, j, val);
}
}
numaDestroy(&na);
FREE(randa);
return pixd;
}
/*!
* applyWarpTransformLUT()
*
* Notes:
* (1) Uses an LUT for computing sin(theta). There is little speed
* advantage to using the LUT.
*/
static l_int32
applyWarpTransformLUT(l_float32 xmag,
l_float32 ymag,
l_float32 xfreq,
l_float32 yfreq,
l_float64 *randa,
l_int32 nx,
l_int32 ny,
l_int32 xp,
l_int32 yp,
l_float32 *lut,
l_int32 npts,
l_float32 *px,
l_float32 *py)
{
l_int32 i;
l_float64 twopi, x, y, anglex, angley, sanglex, sangley;
twopi = 6.283185;
for (i = 0, x = xp; i < nx; i++) {
anglex = xfreq * randa[3 * i + 1] * xp + twopi * randa[3 * i + 2];
angley = yfreq * randa[3 * i + 3] * yp + twopi * randa[3 * i + 4];
sanglex = getSinFromLUT(lut, npts, anglex);
sangley = getSinFromLUT(lut, npts, angley);
x += xmag * randa[3 * i] * sanglex * sangley;
}
for (i = nx, y = yp; i < nx + ny; i++) {
angley = yfreq * randa[3 * i + 1] * yp + twopi * randa[3 * i + 2];
anglex = xfreq * randa[3 * i + 3] * xp + twopi * randa[3 * i + 4];
sanglex = getSinFromLUT(lut, npts, anglex);
sangley = getSinFromLUT(lut, npts, angley);
y += ymag * randa[3 * i] * sangley * sanglex;
}
*px = (l_float32)x;
*py = (l_float32)y;
return 0;
}
static l_int32
makeSinLUT(l_int32 npts,
NUMA **pna)
{
l_int32 i, n;
l_float32 delx, fval;
NUMA *na;
PROCNAME("makeSinLUT");
if (!pna)
return ERROR_INT("&na not defined", procName, 1);
*pna = NULL;
if (npts < 2)
return ERROR_INT("npts < 2", procName, 1);
n = 2 * npts + 1;
na = numaCreate(n);
*pna = na;
delx = 3.14159265 / (l_float32)npts;
numaSetParameters(na, 0.0, delx);
for (i = 0; i < n / 2; i++)
numaAddNumber(na, (l_float32)sin((l_float64)i * delx));
for (i = 0; i < n / 2; i++) {
numaGetFValue(na, i, &fval);
numaAddNumber(na, -fval);
}
numaAddNumber(na, 0);
return 0;
}
static l_float32
getSinFromLUT(l_float32 *tab,
l_int32 npts,
l_float32 radang)
{
l_int32 index;
l_float32 twopi, invtwopi, findex, diff;
/* Restrict radang to [0, 2pi] */
twopi = 6.283185;
invtwopi = 0.1591549;
if (radang < 0.0)
radang += twopi * (1.0 - (l_int32)(-radang * invtwopi));
else if (radang > 0.0)
radang -= twopi * (l_int32)(radang * invtwopi);
/* Interpolate */
findex = (2.0 * (l_float32)npts) * (radang * invtwopi);
index = (l_int32)findex;
if (index == 2 * npts)
return tab[index];
diff = findex - index;
return (1.0 - diff) * tab[index] + diff * tab[index + 1];
}
#endif /* USE_SIN_TABLE */
/*---------------------------------------------------------------------------*
* Stereoscopic warping *
*---------------------------------------------------------------------------*/
/*!
* pixWarpStereoscopic()
*
* Input: pixs (any depth, colormap ok)
* zbend (horizontal separation in pixels of red and cyan
* at the left and right sides, that gives rise to
* quadratic curvature out of the image plane)
* zshiftt (uniform pixel translation difference between
* red and cyan, that pushes the top of the image
* plane away from the viewer (zshiftt > 0) or
* towards the viewer (zshiftt < 0))
* zshiftb (uniform pixel translation difference between
* red and cyan, that pushes the bottom of the image
* plane away from the viewer (zshiftb > 0) or
* towards the viewer (zshiftb < 0))
* ybendt (multiplicative parameter for in-plane vertical
* displacement at the left or right edge at the top:
* y = ybendt * (2x/w - 1)^2 )
* ybendb (same as ybendt, except at the left or right edge
* at the bottom)
* redleft (1 if the red filter is on the left; 0 otherwise)
* Return: pixd (32 bpp), or null on error
*
* Notes:
* (1) This function splits out the red channel, mucks around with
* it, then recombines with the unmolested cyan channel.
* (2) By using a quadratically increasing shift of the red
* pixels horizontally and away from the vertical centerline,
* the image appears to bend quadratically out of the image
* plane, symmetrically with respect to the vertical center
* line. A positive value of @zbend causes the plane to be
* curved away from the viewer. We use linearly interpolated
* stretching to avoid the appearance of kinks in the curve.
* (3) The parameters @zshiftt and @zshiftb tilt the image plane
* about a horizontal line through the center, and at the
* same time move that line either in toward the viewer or away.
* This is implemented by a combination of horizontal shear
* about the center line (for the tilt) and horizontal
* translation (to move the entire plane in or out).
* A positive value of @zshiftt moves the top of the plane
* away from the viewer, and a positive value of @zshiftb
* moves the bottom of the plane away. We use linear interpolated
* shear to avoid visible vertical steps in the tilted image.
* (4) The image can be bent in the plane and about the vertical
* centerline. The centerline does not shift, and the
* parameter @ybend gives the relative shift at left and right
* edges, with a downward shift for positive values of @ybend.
* (6) When writing out a steroscopic (red/cyan) image in jpeg,
* first call pixSetChromaSampling(pix, 0) to get sufficient
* resolution in the red channel.
* (7) Typical values are:
* zbend = 20
* zshiftt = 15
* zshiftb = -15
* ybendt = 30
* ybendb = 0
* If the disparity z-values are too large, it is difficult for
* the brain to register the two images.
* (8) This function has been cleverly reimplemented by Jeff Breidenbach.
* The original implementation used two 32 bpp rgb images,
* and merged them at the end. The result is somewhat faded,
* and has a parameter "thresh" that controls the amount of
* color in the result. (The present implementation avoids these
* two problems, skipping both the colorization and the alpha
* blending at the end, and is about 3x faster)
* The basic operations with 32 bpp are as follows:
* // Immediate conversion to 32 bpp
* Pix *pixt1 = pixConvertTo32(pixs);
* // Do vertical shear
* Pix *pixr = pixQuadraticVerticalShear(pixt1, L_WARP_TO_RIGHT,
* ybendt, ybendb,
* L_BRING_IN_WHITE);
* // Colorize two versions, toward red and cyan
* Pix *pixc = pixCopy(NULL, pixr);
* l_int32 thresh = 150; // if higher, get less original color
* pixColorGray(pixr, NULL, L_PAINT_DARK, thresh, 255, 0, 0);
* pixColorGray(pixc, NULL, L_PAINT_DARK, thresh, 0, 255, 255);
* // Shift the red pixels; e.g., by stretching
* Pix *pixrs = pixStretchHorizontal(pixr, L_WARP_TO_RIGHT,
* L_QUADRATIC_WARP, zbend,
* L_INTERPOLATED,
* L_BRING_IN_WHITE);
* // Blend the shifted red and unshifted cyan 50:50
* Pix *pixg = pixCreate(w, h, 8);
* pixSetAllArbitrary(pixg, 128);
* pixd = pixBlendWithGrayMask(pixrs, pixc, pixg, 0, 0);
*/
PIX *
pixWarpStereoscopic(PIX *pixs,
l_int32 zbend,
l_int32 zshiftt,
l_int32 zshiftb,
l_int32 ybendt,
l_int32 ybendb,
l_int32 redleft)
{
l_int32 w, h, zshift;
l_float32 angle;
BOX *boxleft, *boxright;
PIX *pixt, *pixt2, *pixt3;
PIX *pixr, *pixg, *pixb;
PIX *pixv1, *pixv2, *pixv3, *pixv4;
PIX *pixr1, *pixr2, *pixr3, *pixr4, *pixrs, *pixrss;
PIX *pixd;
PROCNAME("pixWarpStereoscopic");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
/* Convert to the output depth, 32 bpp. */
pixt = pixConvertTo32(pixs);
/* If requested, do a quad vertical shearing, pushing pixels up
* or down, depending on their distance from the centerline. */
pixGetDimensions(pixs, &w, &h, NULL);
boxleft = boxCreate(0, 0, w / 2, h);
boxright = boxCreate(w / 2, 0, w - w / 2, h);
if (ybendt != 0 || ybendb != 0) {
pixv1 = pixClipRectangle(pixt, boxleft, NULL);
pixv2 = pixClipRectangle(pixt, boxright, NULL);
pixv3 = pixQuadraticVShear(pixv1, L_WARP_TO_LEFT, ybendt,
ybendb, L_INTERPOLATED,
L_BRING_IN_WHITE);
pixv4 = pixQuadraticVShear(pixv2, L_WARP_TO_RIGHT, ybendt,
ybendb, L_INTERPOLATED,
L_BRING_IN_WHITE);
pixt2 = pixCreate(w, h, 32);
pixRasterop(pixt2, 0, 0, w / 2, h, PIX_SRC, pixv3, 0, 0);
pixRasterop(pixt2, w / 2, 0, w - w / 2, h, PIX_SRC, pixv4, 0, 0);
pixDestroy(&pixv1);
pixDestroy(&pixv2);
pixDestroy(&pixv3);
pixDestroy(&pixv4);
} else {
pixt2 = pixClone(pixt);
}
/* Split out the 3 components */
pixr = pixGetRGBComponent(pixt2, COLOR_RED);
pixg = pixGetRGBComponent(pixt2, COLOR_GREEN);
pixb = pixGetRGBComponent(pixt2, COLOR_BLUE);
pixDestroy(&pixt);
pixDestroy(&pixt2);
/* The direction of the stereo disparity below is set
* for the red filter to be over the left eye. If the red
* filter is over the right eye, invert the horizontal shifts. */
if (redleft) {
zbend = -zbend;
zshiftt = -zshiftt;
zshiftb = -zshiftb;
}
/* Shift the red pixels horizontally by an amount that
* increases quadratically from the centerline. */
if (zbend == 0) {
pixrs = pixClone(pixr);
} else {
pixr1 = pixClipRectangle(pixr, boxleft, NULL);
pixr2 = pixClipRectangle(pixr, boxright, NULL);
pixr3 = pixStretchHorizontal(pixr1, L_WARP_TO_LEFT, L_QUADRATIC_WARP,
zbend, L_INTERPOLATED, L_BRING_IN_WHITE);
pixr4 = pixStretchHorizontal(pixr2, L_WARP_TO_RIGHT, L_QUADRATIC_WARP,
zbend, L_INTERPOLATED, L_BRING_IN_WHITE);
pixrs = pixCreate(w, h, 8);
pixRasterop(pixrs, 0, 0, w / 2, h, PIX_SRC, pixr3, 0, 0);
pixRasterop(pixrs, w / 2, 0, w - w / 2, h, PIX_SRC, pixr4, 0, 0);
pixDestroy(&pixr1);
pixDestroy(&pixr2);
pixDestroy(&pixr3);
pixDestroy(&pixr4);
}
/* Perform a combination of horizontal shift and shear of
* red pixels. The causes the plane of the image to tilt and
* also move forward or backward. */
if (zshiftt == 0 && zshiftb == 0) {
pixrss = pixClone(pixrs);
} else if (zshiftt == zshiftb) {
pixrss = pixTranslate(NULL, pixrs, zshiftt, 0, L_BRING_IN_WHITE);
} else {
angle = (l_float32)(zshiftb - zshiftt) / (l_float32)pixGetHeight(pixrs);
zshift = (zshiftt + zshiftb) / 2;
pixt3 = pixTranslate(NULL, pixrs, zshift, 0, L_BRING_IN_WHITE);
pixrss = pixHShearLI(pixt3, h / 2, angle, L_BRING_IN_WHITE);
pixDestroy(&pixt3);
}
/* Combine the unchanged cyan (g,b) image with the shifted red */
pixd = pixCreateRGBImage(pixrss, pixg, pixb);
boxDestroy(&boxleft);
boxDestroy(&boxright);
pixDestroy(&pixrs);
pixDestroy(&pixrss);
pixDestroy(&pixr);
pixDestroy(&pixg);
pixDestroy(&pixb);
return pixd;
}
/*----------------------------------------------------------------------*
* Linear and quadratic horizontal stretching *
*----------------------------------------------------------------------*/
/*!
* pixStretchHorizontal()
*
* Input: pixs (1, 8 or 32 bpp)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* type (L_LINEAR_WARP or L_QUADRATIC_WARP)
* hmax (horizontal displacement at edge)
* operation (L_SAMPLED or L_INTERPOLATED)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched/compressed), or null on error
*
* Notes:
* (1) If @hmax > 0, this is an increase in the coordinate value of
* pixels in pixd, relative to the same pixel in pixs.
* (2) If @dir == L_WARP_TO_LEFT, the pixels on the right edge of
* the image are not moved. So, for example, if @hmax > 0
* and @dir == L_WARP_TO_LEFT, the pixels in pixd are
* contracted toward the right edge of the image, relative
* to those in pixs.
* (3) If @type == L_LINEAR_WARP, the pixel positions are moved
* to the left or right by an amount that varies linearly with
* the horizontal location.
* (4) If @operation == L_SAMPLED, the dest pixels are taken from
* the nearest src pixel. Otherwise, we use linear interpolation
* between pairs of sampled pixels.
*/
PIX *
pixStretchHorizontal(PIX *pixs,
l_int32 dir,
l_int32 type,
l_int32 hmax,
l_int32 operation,
l_int32 incolor)
{
l_int32 d;
PROCNAME("pixStretchHorizontal");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
d = pixGetDepth(pixs);
if (d != 1 && d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 1, 8 or 32 bpp", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (type != L_LINEAR_WARP && type != L_QUADRATIC_WARP)
return (PIX *)ERROR_PTR("invalid type", procName, NULL);
if (operation != L_SAMPLED && operation != L_INTERPOLATED)
return (PIX *)ERROR_PTR("invalid operation", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
if (d == 1 && operation == L_INTERPOLATED) {
L_WARNING("Using sampling for 1 bpp\n", procName);
operation = L_INTERPOLATED;
}
if (operation == L_SAMPLED)
return pixStretchHorizontalSampled(pixs, dir, type, hmax, incolor);
else
return pixStretchHorizontalLI(pixs, dir, type, hmax, incolor);
}
/*!
* pixStretchHorizontalSampled()
*
* Input: pixs (1, 8 or 32 bpp)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* type (L_LINEAR_WARP or L_QUADRATIC_WARP)
* hmax (horizontal displacement at edge)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched/compressed), or null on error
*
* Notes:
* (1) See pixStretchHorizontal() for details.
*/
PIX *
pixStretchHorizontalSampled(PIX *pixs,
l_int32 dir,
l_int32 type,
l_int32 hmax,
l_int32 incolor)
{
l_int32 i, j, jd, w, wm, h, d, wpls, wpld, val;
l_uint32 *datas, *datad, *lines, *lined;
PIX *pixd;
PROCNAME("pixStretchHorizontalSampled");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 1 && d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 1, 8 or 32 bpp", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (type != L_LINEAR_WARP && type != L_QUADRATIC_WARP)
return (PIX *)ERROR_PTR("invalid type", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
pixd = pixCreateTemplate(pixs);
pixSetBlackOrWhite(pixd, L_BRING_IN_WHITE);
datas = pixGetData(pixs);
datad = pixGetData(pixd);
wpls = pixGetWpl(pixs);
wpld = pixGetWpl(pixd);
wm = w - 1;
for (jd = 0; jd < w; jd++) {
if (dir == L_WARP_TO_LEFT) {
if (type == L_LINEAR_WARP)
j = jd - (hmax * (wm - jd)) / wm;
else /* L_QUADRATIC_WARP */
j = jd - (hmax * (wm - jd) * (wm - jd)) / (wm * wm);
} else if (dir == L_WARP_TO_RIGHT) {
if (type == L_LINEAR_WARP)
j = jd - (hmax * jd) / wm;
else /* L_QUADRATIC_WARP */
j = jd - (hmax * jd * jd) / (wm * wm);
}
if (j < 0 || j > w - 1) continue;
switch (d)
{
case 1:
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
val = GET_DATA_BIT(lines, j);
if (val)
SET_DATA_BIT(lined, jd);
}
break;
case 8:
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
val = GET_DATA_BYTE(lines, j);
SET_DATA_BYTE(lined, jd, val);
}
break;
case 32:
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
lined[jd] = lines[j];
}
break;
default:
L_ERROR("invalid depth: %d\n", procName, d);
pixDestroy(&pixd);
return NULL;
}
}
return pixd;
}
/*!
* pixStretchHorizontalLI()
*
* Input: pixs (1, 8 or 32 bpp)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* type (L_LINEAR_WARP or L_QUADRATIC_WARP)
* hmax (horizontal displacement at edge)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched/compressed), or null on error
*
* Notes:
* (1) See pixStretchHorizontal() for details.
*/
PIX *
pixStretchHorizontalLI(PIX *pixs,
l_int32 dir,
l_int32 type,
l_int32 hmax,
l_int32 incolor)
{
l_int32 i, j, jd, jp, jf, w, wm, h, d, wpls, wpld, val, rval, gval, bval;
l_uint32 word0, word1;
l_uint32 *datas, *datad, *lines, *lined;
PIX *pixd;
PROCNAME("pixStretchHorizontalLI");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 8 or 32 bpp", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (type != L_LINEAR_WARP && type != L_QUADRATIC_WARP)
return (PIX *)ERROR_PTR("invalid type", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
/* Standard linear interpolation, subdividing each pixel into 64 */
pixd = pixCreateTemplate(pixs);
pixSetBlackOrWhite(pixd, L_BRING_IN_WHITE);
datas = pixGetData(pixs);
datad = pixGetData(pixd);
wpls = pixGetWpl(pixs);
wpld = pixGetWpl(pixd);
wm = w - 1;
for (jd = 0; jd < w; jd++) {
if (dir == L_WARP_TO_LEFT) {
if (type == L_LINEAR_WARP)
j = 64 * jd - 64 * (hmax * (wm - jd)) / wm;
else /* L_QUADRATIC_WARP */
j = 64 * jd - 64 * (hmax * (wm - jd) * (wm - jd)) / (wm * wm);
} else if (dir == L_WARP_TO_RIGHT) {
if (type == L_LINEAR_WARP)
j = 64 * jd - 64 * (hmax * jd) / wm;
else /* L_QUADRATIC_WARP */
j = 64 * jd - 64 * (hmax * jd * jd) / (wm * wm);
}
jp = j / 64;
jf = j & 0x3f;
if (jp < 0 || jp > wm) continue;
switch (d)
{
case 8:
if (jp < wm) {
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
val = ((63 - jf) * GET_DATA_BYTE(lines, jp) +
jf * GET_DATA_BYTE(lines, jp + 1) + 31) / 63;
SET_DATA_BYTE(lined, jd, val);
}
} else { /* jp == wm */
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
val = GET_DATA_BYTE(lines, jp);
SET_DATA_BYTE(lined, jd, val);
}
}
break;
case 32:
if (jp < wm) {
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
word0 = *(lines + jp);
word1 = *(lines + jp + 1);
rval = ((63 - jf) * ((word0 >> L_RED_SHIFT) & 0xff) +
jf * ((word1 >> L_RED_SHIFT) & 0xff) + 31) / 63;
gval = ((63 - jf) * ((word0 >> L_GREEN_SHIFT) & 0xff) +
jf * ((word1 >> L_GREEN_SHIFT) & 0xff) + 31) / 63;
bval = ((63 - jf) * ((word0 >> L_BLUE_SHIFT) & 0xff) +
jf * ((word1 >> L_BLUE_SHIFT) & 0xff) + 31) / 63;
composeRGBPixel(rval, gval, bval, lined + jd);
}
} else { /* jp == wm */
for (i = 0; i < h; i++) {
lines = datas + i * wpls;
lined = datad + i * wpld;
lined[jd] = lines[jp];
}
}
break;
default:
L_ERROR("invalid depth: %d\n", procName, d);
pixDestroy(&pixd);
return NULL;
}
}
return pixd;
}
/*----------------------------------------------------------------------*
* Quadratic vertical shear *
*----------------------------------------------------------------------*/
/*!
* pixQuadraticVShear()
*
* Input: pixs (1, 8 or 32 bpp)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* vmaxt (max vertical displacement at edge and at top)
* vmaxb (max vertical displacement at edge and at bottom)
* operation (L_SAMPLED or L_INTERPOLATED)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched), or null on error
*
* Notes:
* (1) This gives a quadratic bending, upward or downward, as you
* move to the left or right.
* (2) If @dir == L_WARP_TO_LEFT, the right edge is unchanged, and
* the left edge pixels are moved maximally up or down.
* (3) Parameters @vmaxt and @vmaxb control the maximum amount of
* vertical pixel shear at the top and bottom, respectively.
* If @vmaxt > 0, the vertical displacement of pixels at the
* top is downward. Likewise, if @vmaxb > 0, the vertical
* displacement of pixels at the bottom is downward.
* (4) If @operation == L_SAMPLED, the dest pixels are taken from
* the nearest src pixel. Otherwise, we use linear interpolation
* between pairs of sampled pixels.
* (5) This is for quadratic shear. For uniform (linear) shear,
* use the standard shear operators.
*/
PIX *
pixQuadraticVShear(PIX *pixs,
l_int32 dir,
l_int32 vmaxt,
l_int32 vmaxb,
l_int32 operation,
l_int32 incolor)
{
l_int32 w, h, d;
PROCNAME("pixQuadraticVShear");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 1 && d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 1, 8 or 32 bpp", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (operation != L_SAMPLED && operation != L_INTERPOLATED)
return (PIX *)ERROR_PTR("invalid operation", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
if (vmaxt == 0 && vmaxb == 0)
return pixCopy(NULL, pixs);
if (operation == L_INTERPOLATED && d == 1) {
L_WARNING("no interpolation for 1 bpp; using sampling\n", procName);
operation = L_SAMPLED;
}
if (operation == L_SAMPLED)
return pixQuadraticVShearSampled(pixs, dir, vmaxt, vmaxb, incolor);
else /* operation == L_INTERPOLATED */
return pixQuadraticVShearLI(pixs, dir, vmaxt, vmaxb, incolor);
}
/*!
* pixQuadraticVShearSampled()
*
* Input: pixs (1, 8 or 32 bpp)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* vmaxt (max vertical displacement at edge and at top)
* vmaxb (max vertical displacement at edge and at bottom)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched), or null on error
*
* Notes:
* (1) See pixQuadraticVShear() for details.
*/
PIX *
pixQuadraticVShearSampled(PIX *pixs,
l_int32 dir,
l_int32 vmaxt,
l_int32 vmaxb,
l_int32 incolor)
{
l_int32 i, j, id, w, h, d, wm, hm, wpls, wpld, val;
l_uint32 *datas, *datad, *lines, *lined;
l_float32 delrowt, delrowb, denom1, denom2, dely;
PIX *pixd;
PROCNAME("pixQuadraticVShearSampled");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d != 1 && d != 8 && d != 32)
return (PIX *)ERROR_PTR("pixs not 1, 8 or 32 bpp", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
if (vmaxt == 0 && vmaxb == 0)
return pixCopy(NULL, pixs);
pixd = pixCreateTemplate(pixs);
pixSetBlackOrWhite(pixd, L_BRING_IN_WHITE);
datas = pixGetData(pixs);
datad = pixGetData(pixd);
wpls = pixGetWpl(pixs);
wpld = pixGetWpl(pixd);
wm = w - 1;
hm = h - 1;
denom1 = 1. / (l_float32)h;
denom2 = 1. / (l_float32)(wm * wm);
for (j = 0; j < w; j++) {
if (dir == L_WARP_TO_LEFT) {
delrowt = (l_float32)(vmaxt * (wm - j) * (wm - j)) * denom2;
delrowb = (l_float32)(vmaxb * (wm - j) * (wm - j)) * denom2;
} else if (dir == L_WARP_TO_RIGHT) {
delrowt = (l_float32)(vmaxt * j * j) * denom2;
delrowb = (l_float32)(vmaxb * j * j) * denom2;
}
switch (d)
{
case 1:
for (id = 0; id < h; id++) {
dely = (delrowt * (hm - id) + delrowb * id) * denom1;
i = id - (l_int32)(dely + 0.5);
if (i < 0 || i > hm) continue;
lines = datas + i * wpls;
lined = datad + id * wpld;
val = GET_DATA_BIT(lines, j);
if (val)
SET_DATA_BIT(lined, j);
}
break;
case 8:
for (id = 0; id < h; id++) {
dely = (delrowt * (hm - id) + delrowb * id) * denom1;
i = id - (l_int32)(dely + 0.5);
if (i < 0 || i > hm) continue;
lines = datas + i * wpls;
lined = datad + id * wpld;
val = GET_DATA_BYTE(lines, j);
SET_DATA_BYTE(lined, j, val);
}
break;
case 32:
for (id = 0; id < h; id++) {
dely = (delrowt * (hm - id) + delrowb * id) * denom1;
i = id - (l_int32)(dely + 0.5);
if (i < 0 || i > hm) continue;
lines = datas + i * wpls;
lined = datad + id * wpld;
lined[j] = lines[j];
}
break;
default:
L_ERROR("invalid depth: %d\n", procName, d);
pixDestroy(&pixd);
return NULL;
}
}
return pixd;
}
/*!
* pixQuadraticVShearLI()
*
* Input: pixs (8 or 32 bpp, or colormapped)
* dir (L_WARP_TO_LEFT or L_WARP_TO_RIGHT)
* vmaxt (max vertical displacement at edge and at top)
* vmaxb (max vertical displacement at edge and at bottom)
* incolor (L_BRING_IN_WHITE or L_BRING_IN_BLACK)
* Return: pixd (stretched), or null on error
*
* Notes:
* (1) See pixQuadraticVShear() for details.
*/
PIX *
pixQuadraticVShearLI(PIX *pixs,
l_int32 dir,
l_int32 vmaxt,
l_int32 vmaxb,
l_int32 incolor)
{
l_int32 i, j, id, yp, yf, w, h, d, wm, hm, wpls, wpld;
l_int32 val, rval, gval, bval;
l_uint32 word0, word1;
l_uint32 *datas, *datad, *lines, *lined;
l_float32 delrowt, delrowb, denom1, denom2, dely;
PIX *pix, *pixd;
PIXCMAP *cmap;
PROCNAME("pixQuadraticVShearLI");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
pixGetDimensions(pixs, &w, &h, &d);
if (d == 1)
return (PIX *)ERROR_PTR("pixs is 1 bpp", procName, NULL);
cmap = pixGetColormap(pixs);
if (d != 8 && d != 32 && !cmap)
return (PIX *)ERROR_PTR("pixs not 8, 32 bpp, or cmap", procName, NULL);
if (dir != L_WARP_TO_LEFT && dir != L_WARP_TO_RIGHT)
return (PIX *)ERROR_PTR("invalid direction", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
if (vmaxt == 0 && vmaxb == 0)
return pixCopy(NULL, pixs);
/* Remove any existing colormap */
if (cmap)
pix = pixRemoveColormap(pixs, REMOVE_CMAP_BASED_ON_SRC);
else
pix = pixClone(pixs);
d = pixGetDepth(pix);
if (d != 8 && d != 32) {
pixDestroy(&pix);
return (PIX *)ERROR_PTR("invalid depth", procName, NULL);
}
/* Standard linear interp: subdivide each pixel into 64 parts */
pixd = pixCreateTemplate(pix);
pixSetBlackOrWhite(pixd, L_BRING_IN_WHITE);
datas = pixGetData(pix);
datad = pixGetData(pixd);
wpls = pixGetWpl(pix);
wpld = pixGetWpl(pixd);
wm = w - 1;
hm = h - 1;
denom1 = 1.0 / (l_float32)h;
denom2 = 1.0 / (l_float32)(wm * wm);
for (j = 0; j < w; j++) {
if (dir == L_WARP_TO_LEFT) {
delrowt = (l_float32)(vmaxt * (wm - j) * (wm - j)) * denom2;
delrowb = (l_float32)(vmaxb * (wm - j) * (wm - j)) * denom2;
} else if (dir == L_WARP_TO_RIGHT) {
delrowt = (l_float32)(vmaxt * j * j) * denom2;
delrowb = (l_float32)(vmaxb * j * j) * denom2;
}
switch (d)
{
case 8:
for (id = 0; id < h; id++) {
dely = (delrowt * (hm - id) + delrowb * id) * denom1;
i = 64 * id - (l_int32)(64.0 * dely);
yp = i / 64;
yf = i & 63;
if (yp < 0 || yp > hm) continue;
lines = datas + yp * wpls;
lined = datad + id * wpld;
if (yp < hm) {
val = ((63 - yf) * GET_DATA_BYTE(lines, j) +
yf * GET_DATA_BYTE(lines + wpls, j) + 31) / 63;
} else { /* yp == hm */
val = GET_DATA_BYTE(lines, j);
}
SET_DATA_BYTE(lined, j, val);
}
break;
case 32:
for (id = 0; id < h; id++) {
dely = (delrowt * (hm - id) + delrowb * id) * denom1;
i = 64 * id - (l_int32)(64.0 * dely);
yp = i / 64;
yf = i & 63;
if (yp < 0 || yp > hm) continue;
lines = datas + yp * wpls;
lined = datad + id * wpld;
if (yp < hm) {
word0 = *(lines + j);
word1 = *(lines + wpls + j);
rval = ((63 - yf) * ((word0 >> L_RED_SHIFT) & 0xff) +
yf * ((word1 >> L_RED_SHIFT) & 0xff) + 31) / 63;
gval = ((63 - yf) * ((word0 >> L_GREEN_SHIFT) & 0xff) +
yf * ((word1 >> L_GREEN_SHIFT) & 0xff) + 31) / 63;
bval = ((63 - yf) * ((word0 >> L_BLUE_SHIFT) & 0xff) +
yf * ((word1 >> L_BLUE_SHIFT) & 0xff) + 31) / 63;
composeRGBPixel(rval, gval, bval, lined + j);
} else { /* yp == hm */
lined[j] = lines[j];
}
}
break;
default:
L_ERROR("invalid depth: %d\n", procName, d);
pixDestroy(&pix);
pixDestroy(&pixd);
return NULL;
}
}
pixDestroy(&pix);
return pixd;
}
/*----------------------------------------------------------------------*
* Stereo from a pair of images *
*----------------------------------------------------------------------*/
/*!
* pixStereoFromPair()
*
* Input: pix1 (32 bpp rgb)
* pix2 (32 bpp rgb)
* rwt, gwt, bwt (weighting factors used for each component in
pix1 to determine the output red channel)
* Return: pixd (stereo enhanced), or null on error
*
* Notes:
* (1) pix1 and pix2 are a pair of stereo images, ideally taken
* concurrently in the same plane, with some lateral translation.
* (2) The output red channel is determined from @pix1.
* The output green and blue channels are taken from the green
* and blue channels, respectively, of @pix2.
* (3) The weights determine how much of each component in @pix1
* goes into the output red channel. The sum of weights
* must be 1.0. If it's not, we scale the weights to
* satisfy this criterion.
* (4) The most general pixel mapping allowed here is:
* rval = rwt * r1 + gwt * g1 + bwt * b1 (from pix1)
* gval = g2 (from pix2)
* bval = b2 (from pix2)
* (5) The simplest method is to use rwt = 1.0, gwt = 0.0, bwt = 0.0,
* but this causes unpleasant visual artifacts with red in the image.
* Use of green and blue from @pix1 in the red channel,
* instead of red, tends to fix that problem.
*/
PIX *
pixStereoFromPair(PIX *pix1,
PIX *pix2,
l_float32 rwt,
l_float32 gwt,
l_float32 bwt)
{
l_int32 i, j, w, h, wpl1, wpl2, rval, gval, bval;
l_uint32 word1, word2;
l_uint32 *data1, *data2, *datad, *line1, *line2, *lined;
l_float32 sum;
PIX *pixd;
PROCNAME("pixStereoFromPair");
if (!pix1 || !pix2)
return (PIX *)ERROR_PTR("pix1, pix2 not both defined", procName, NULL);
if (pixGetDepth(pix1) != 32 || pixGetDepth(pix2) != 32)
return (PIX *)ERROR_PTR("pix1, pix2 not both 32 bpp", procName, NULL);
/* Make sure the sum of weights is 1.0; otherwise, you can get
* overflow in the gray value. */
if (rwt == 0.0 && gwt == 0.0 && bwt == 0.0) {
rwt = L_DEFAULT_RED_WEIGHT;
gwt = L_DEFAULT_GREEN_WEIGHT;
bwt = L_DEFAULT_BLUE_WEIGHT;
}
sum = rwt + gwt + bwt;
if (L_ABS(sum - 1.0) > 0.0001) { /* maintain ratios with sum == 1.0 */
L_WARNING("weights don't sum to 1; maintaining ratios\n", procName);
rwt = rwt / sum;
gwt = gwt / sum;
bwt = bwt / sum;
}
pixGetDimensions(pix1, &w, &h, NULL);
pixd = pixCreateTemplate(pix1);
data1 = pixGetData(pix1);
data2 = pixGetData(pix2);
datad = pixGetData(pixd);
wpl1 = pixGetWpl(pix1);
wpl2 = pixGetWpl(pix2);
for (i = 0; i < h; i++) {
line1 = data1 + i * wpl1;
line2 = data2 + i * wpl2;
lined = datad + i * wpl1; /* wpl1 works for pixd */
for (j = 0; j < w; j++) {
word1 = *(line1 + j);
word2 = *(line2 + j);
rval = (l_int32)(rwt * ((word1 >> L_RED_SHIFT) & 0xff) +
gwt * ((word1 >> L_GREEN_SHIFT) & 0xff) +
bwt * ((word1 >> L_BLUE_SHIFT) & 0xff) + 0.5);
gval = (word2 >> L_GREEN_SHIFT) & 0xff;
bval = (word2 >> L_BLUE_SHIFT) & 0xff;
composeRGBPixel(rval, gval, bval, lined + j);
}
}
return pixd;
}