/*====================================================================*
- 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.
*====================================================================*/
/*!
* \file rotateam.c
*
*
* Grayscale and color rotation for area mapping (== interpolation)
*
* Rotation about the image center
* PIX *pixRotateAM()
* PIX *pixRotateAMColor()
* PIX *pixRotateAMGray()
* static void rotateAMColorLow()
* static void rotateAMGrayLow()
*
* Rotation about the UL corner of the image
* PIX *pixRotateAMCorner()
* PIX *pixRotateAMColorCorner()
* PIX *pixRotateAMGrayCorner()
* static void rotateAMColorCornerLow()
* static void rotateAMGrayCornerLow()
*
* Faster color rotation about the image center
* PIX *pixRotateAMColorFast()
* static void rotateAMColorFastLow()
*
* Rotations are measured in radians; clockwise is positive.
*
* The basic area mapping grayscale rotation works on 8 bpp images.
* For color, the same method is applied to each color separately.
* This can be done in two ways: (1) as here, computing each dest
* rgb pixel from the appropriate four src rgb pixels, or (2) separating
* the color image into three 8 bpp images, rotate each of these,
* and then combine the result. Method (1) is about 2.5x faster.
* We have also implemented a fast approximation for color area-mapping
* rotation (pixRotateAMColorFast()), which is about 25% faster
* than the standard color rotator. If you need the extra speed,
* use it.
*
* Area mapping works as follows. For each dest
* pixel you find the 4 source pixels that it partially
* covers. You then compute the dest pixel value as
* the area-weighted average of those 4 source pixels.
* We make two simplifying approximations:
*
* ~ For simplicity, compute the areas as if the dest
* pixel were translated but not rotated.
*
* ~ Compute area overlaps on a discrete sub-pixel grid.
* Because we are using 8 bpp images with 256 levels,
* it is convenient to break each pixel into a
* 16x16 sub-pixel grid, and count the number of
* overlapped sub-pixels.
*
* It is interesting to note that the digital filter that
* implements the area mapping algorithm for rotation
* is identical to the digital filter used for linear
* interpolation when arbitrarily scaling grayscale images.
*
* The advantage of area mapping over pixel sampling
* in grayscale rotation is that the former naturally
* blurs sharp edges ("anti-aliasing"), so that stair-step
* artifacts are not introduced. The disadvantage is that
* it is significantly slower.
*
* But it is still pretty fast. With standard 3 GHz hardware,
* the anti-aliased (area-mapped) color rotation speed is
* about 15 million pixels/sec.
*
* The function pixRotateAMColorFast() is about 10-20% faster
* than pixRotateAMColor(). The quality is slightly worse,
* and if you make many successive small rotations, with a
* total angle of 360 degrees, it has been noted that the
* center wanders -- it seems to be doing a 1 pixel translation
* in addition to the rotation.
*
* Consider again the comparison of image quality between sampling
* and area mapping. With sampling, sharp edges such as found in
* text images remain sharp. However, sampling artifacts such as
* characters randomly bouncing up and down by one pixel, or
* one pixel horizontal shear lines going through a line of text
* (causing the characters to look like badly rendered italic),
* are highly visible. It does not help to sample the source pixel
* with the largest area covering each dest pixel; the result has
* the same ugly sampling artifacts.
*
* With area mapping, these annoying artifacts are avoided, but the
* blurring of edges makes small text a bit more difficult to read.
* However, if you are willing to do more computation, you can have
* the best of both worlds: no sampling artifacts and sharp edges.
* Use area mapping to avoid sampling issues, and follow it with
* unsharp masking. Experiment with the sharpening parameters.
* I have found that a small amount of sharpening is sufficient to
* restore the sharp edges in text; e.g.,
* pix2 = pixUnsharpMasking(pix1, 1, 0.3);
*
*/
#ifdef HAVE_CONFIG_H
#include
#endif /* HAVE_CONFIG_H */
#include
#include /* required for sin and tan */
#include "allheaders.h"
static void rotateAMColorLow(l_uint32 *datad, l_int32 w, l_int32 h,
l_int32 wpld, l_uint32 *datas, l_int32 wpls,
l_float32 angle, l_uint32 colorval);
static void rotateAMGrayLow(l_uint32 *datad, l_int32 w, l_int32 h,
l_int32 wpld, l_uint32 *datas, l_int32 wpls,
l_float32 angle, l_uint8 grayval);
static void rotateAMColorCornerLow(l_uint32 *datad, l_int32 w, l_int32 h,
l_int32 wpld, l_uint32 *datas,
l_int32 wpls, l_float32 angle,
l_uint32 colorval);
static void rotateAMGrayCornerLow(l_uint32 *datad, l_int32 w, l_int32 h,
l_int32 wpld, l_uint32 *datas, l_int32 wpls,
l_float32 angle, l_uint8 grayval);
static void rotateAMColorFastLow(l_uint32 *datad, l_int32 w, l_int32 h,
l_int32 wpld, l_uint32 *datas, l_int32 wpls,
l_float32 angle, l_uint32 colorval);
static const l_float32 MinAngleToRotate = 0.001f; /* radians; ~0.06 deg */
/*------------------------------------------------------------------*
* Rotation about the center *
*------------------------------------------------------------------*/
/*!
* \brief pixRotateAM()
*
* \param[in] pixs 2, 4, 8 bpp gray or colormapped, or 32 bpp RGB
* \param[in] angle radians; clockwise is positive
* \param[in] incolor L_BRING_IN_WHITE, L_BRING_IN_BLACK
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates about image center.
* (2) A positive angle gives a clockwise rotation.
* (3) Brings in either black or white pixels from the boundary.
*
*/
PIX *
pixRotateAM(PIX *pixs,
l_float32 angle,
l_int32 incolor)
{
l_int32 d;
l_uint32 fillval;
PIX *pixt1, *pixt2, *pixd;
PROCNAME("pixRotateAM");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) == 1)
return (PIX *)ERROR_PTR("pixs is 1 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
/* Remove cmap if it exists, and unpack to 8 bpp if necessary */
pixt1 = pixRemoveColormap(pixs, REMOVE_CMAP_BASED_ON_SRC);
d = pixGetDepth(pixt1);
if (d < 8)
pixt2 = pixConvertTo8(pixt1, FALSE);
else
pixt2 = pixClone(pixt1);
d = pixGetDepth(pixt2);
/* Compute actual incoming color */
fillval = 0;
if (incolor == L_BRING_IN_WHITE) {
if (d == 8)
fillval = 255;
else /* d == 32 */
fillval = 0xffffff00;
}
if (d == 8)
pixd = pixRotateAMGray(pixt2, angle, fillval);
else /* d == 32 */
pixd = pixRotateAMColor(pixt2, angle, fillval);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
return pixd;
}
/*!
* \brief pixRotateAMColor()
*
* \param[in] pixs 32 bpp
* \param[in] angle radians; clockwise is positive
* \param[in] colorval e.g., 0 to bring in BLACK, 0xffffff00 for WHITE
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates about image center.
* (2) A positive angle gives a clockwise rotation.
* (3) Specify the color to be brought in from outside the image.
*
*/
PIX *
pixRotateAMColor(PIX *pixs,
l_float32 angle,
l_uint32 colorval)
{
l_int32 w, h, wpls, wpld;
l_uint32 *datas, *datad;
PIX *pix1, *pix2, *pixd;
PROCNAME("pixRotateAMColor");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs must be 32 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixd = pixCreateTemplate(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
rotateAMColorLow(datad, w, h, wpld, datas, wpls, angle, colorval);
if (pixGetSpp(pixs) == 4) {
pix1 = pixGetRGBComponent(pixs, L_ALPHA_CHANNEL);
pix2 = pixRotateAMGray(pix1, angle, 255); /* bring in opaque */
pixSetRGBComponent(pixd, pix2, L_ALPHA_CHANNEL);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
return pixd;
}
/*!
* \brief pixRotateAMGray()
*
* \param[in] pixs 8 bpp
* \param[in] angle radians; clockwise is positive
* \param[in] grayval 0 to bring in BLACK, 255 for WHITE
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates about image center.
* (2) A positive angle gives a clockwise rotation.
* (3) Specify the grayvalue to be brought in from outside the image.
*
*/
PIX *
pixRotateAMGray(PIX *pixs,
l_float32 angle,
l_uint8 grayval)
{
l_int32 w, h, wpls, wpld;
l_uint32 *datas, *datad;
PIX *pixd;
PROCNAME("pixRotateAMGray");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 8)
return (PIX *)ERROR_PTR("pixs must be 8 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixd = pixCreateTemplate(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
rotateAMGrayLow(datad, w, h, wpld, datas, wpls, angle, grayval);
return pixd;
}
static void
rotateAMColorLow(l_uint32 *datad,
l_int32 w,
l_int32 h,
l_int32 wpld,
l_uint32 *datas,
l_int32 wpls,
l_float32 angle,
l_uint32 colorval)
{
l_int32 i, j, xcen, ycen, wm2, hm2;
l_int32 xdif, ydif, xpm, ypm, xp, yp, xf, yf;
l_int32 rval, gval, bval;
l_uint32 word00, word01, word10, word11;
l_uint32 *lines, *lined;
l_float32 sina, cosa;
xcen = w / 2;
wm2 = w - 2;
ycen = h / 2;
hm2 = h - 2;
sina = 16. * sin(angle);
cosa = 16. * cos(angle);
for (i = 0; i < h; i++) {
ydif = ycen - i;
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
xdif = xcen - j;
xpm = (l_int32)(-xdif * cosa - ydif * sina);
ypm = (l_int32)(-ydif * cosa + xdif * sina);
xp = xcen + (xpm >> 4);
yp = ycen + (ypm >> 4);
xf = xpm & 0x0f;
yf = ypm & 0x0f;
/* if off the edge, write input colorval */
if (xp < 0 || yp < 0 || xp > wm2 || yp > hm2) {
*(lined + j) = colorval;
continue;
}
lines = datas + yp * wpls;
/* do area weighting. Without this, we would
* simply do:
* *(lined + j) = *(lines + xp);
* which is faster but gives lousy results!
*/
word00 = *(lines + xp);
word10 = *(lines + xp + 1);
word01 = *(lines + wpls + xp);
word11 = *(lines + wpls + xp + 1);
rval = ((16 - xf) * (16 - yf) * ((word00 >> L_RED_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_RED_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_RED_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_RED_SHIFT) & 0xff) + 128) / 256;
gval = ((16 - xf) * (16 - yf) * ((word00 >> L_GREEN_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_GREEN_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_GREEN_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_GREEN_SHIFT) & 0xff) + 128) / 256;
bval = ((16 - xf) * (16 - yf) * ((word00 >> L_BLUE_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_BLUE_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_BLUE_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_BLUE_SHIFT) & 0xff) + 128) / 256;
composeRGBPixel(rval, gval, bval, lined + j);
}
}
}
static void
rotateAMGrayLow(l_uint32 *datad,
l_int32 w,
l_int32 h,
l_int32 wpld,
l_uint32 *datas,
l_int32 wpls,
l_float32 angle,
l_uint8 grayval)
{
l_int32 i, j, xcen, ycen, wm2, hm2;
l_int32 xdif, ydif, xpm, ypm, xp, yp, xf, yf;
l_int32 v00, v01, v10, v11;
l_uint8 val;
l_uint32 *lines, *lined;
l_float32 sina, cosa;
xcen = w / 2;
wm2 = w - 2;
ycen = h / 2;
hm2 = h - 2;
sina = 16. * sin(angle);
cosa = 16. * cos(angle);
for (i = 0; i < h; i++) {
ydif = ycen - i;
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
xdif = xcen - j;
xpm = (l_int32)(-xdif * cosa - ydif * sina);
ypm = (l_int32)(-ydif * cosa + xdif * sina);
xp = xcen + (xpm >> 4);
yp = ycen + (ypm >> 4);
xf = xpm & 0x0f;
yf = ypm & 0x0f;
/* if off the edge, write input grayval */
if (xp < 0 || yp < 0 || xp > wm2 || yp > hm2) {
SET_DATA_BYTE(lined, j, grayval);
continue;
}
lines = datas + yp * wpls;
/* do area weighting. Without this, we would
* simply do:
* SET_DATA_BYTE(lined, j, GET_DATA_BYTE(lines, xp));
* which is faster but gives lousy results!
*/
v00 = (16 - xf) * (16 - yf) * GET_DATA_BYTE(lines, xp);
v10 = xf * (16 - yf) * GET_DATA_BYTE(lines, xp + 1);
v01 = (16 - xf) * yf * GET_DATA_BYTE(lines + wpls, xp);
v11 = xf * yf * GET_DATA_BYTE(lines + wpls, xp + 1);
val = (l_uint8)((v00 + v01 + v10 + v11 + 128) / 256);
SET_DATA_BYTE(lined, j, val);
}
}
}
/*------------------------------------------------------------------*
* Rotation about the UL corner *
*------------------------------------------------------------------*/
/*!
* \brief pixRotateAMCorner()
*
* \param[in] pixs 1, 2, 4, 8 bpp gray or colormapped, or 32 bpp RGB
* \param[in] angle radians; clockwise is positive
* \param[in] incolor L_BRING_IN_WHITE, L_BRING_IN_BLACK
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates about the UL corner of the image.
* (2) A positive angle gives a clockwise rotation.
* (3) Brings in either black or white pixels from the boundary.
*
*/
PIX *
pixRotateAMCorner(PIX *pixs,
l_float32 angle,
l_int32 incolor)
{
l_int32 d;
l_uint32 fillval;
PIX *pixt1, *pixt2, *pixd;
PROCNAME("pixRotateAMCorner");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
/* Remove cmap if it exists, and unpack to 8 bpp if necessary */
pixt1 = pixRemoveColormap(pixs, REMOVE_CMAP_BASED_ON_SRC);
d = pixGetDepth(pixt1);
if (d < 8)
pixt2 = pixConvertTo8(pixt1, FALSE);
else
pixt2 = pixClone(pixt1);
d = pixGetDepth(pixt2);
/* Compute actual incoming color */
fillval = 0;
if (incolor == L_BRING_IN_WHITE) {
if (d == 8)
fillval = 255;
else /* d == 32 */
fillval = 0xffffff00;
}
if (d == 8)
pixd = pixRotateAMGrayCorner(pixt2, angle, fillval);
else /* d == 32 */
pixd = pixRotateAMColorCorner(pixt2, angle, fillval);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
return pixd;
}
/*!
* \brief pixRotateAMColorCorner()
*
* \param[in] pixs
* \param[in] angle radians; clockwise is positive
* \param[in] fillval e.g., 0 to bring in BLACK, 0xffffff00 for WHITE
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates the image about the UL corner.
* (2) A positive angle gives a clockwise rotation.
* (3) Specify the color to be brought in from outside the image.
*
*/
PIX *
pixRotateAMColorCorner(PIX *pixs,
l_float32 angle,
l_uint32 fillval)
{
l_int32 w, h, wpls, wpld;
l_uint32 *datas, *datad;
PIX *pix1, *pix2, *pixd;
PROCNAME("pixRotateAMColorCorner");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs must be 32 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixd = pixCreateTemplate(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
rotateAMColorCornerLow(datad, w, h, wpld, datas, wpls, angle, fillval);
if (pixGetSpp(pixs) == 4) {
pix1 = pixGetRGBComponent(pixs, L_ALPHA_CHANNEL);
pix2 = pixRotateAMGrayCorner(pix1, angle, 255); /* bring in opaque */
pixSetRGBComponent(pixd, pix2, L_ALPHA_CHANNEL);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
return pixd;
}
/*!
* \brief pixRotateAMGrayCorner()
*
* \param[in] pixs
* \param[in] angle radians; clockwise is positive
* \param[in] grayval 0 to bring in BLACK, 255 for WHITE
* \return pixd, or NULL on error
*
*
* Notes:
* (1) Rotates the image about the UL corner.
* (2) A positive angle gives a clockwise rotation.
* (3) Specify the grayvalue to be brought in from outside the image.
*
*/
PIX *
pixRotateAMGrayCorner(PIX *pixs,
l_float32 angle,
l_uint8 grayval)
{
l_int32 w, h, wpls, wpld;
l_uint32 *datas, *datad;
PIX *pixd;
PROCNAME("pixRotateAMGrayCorner");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 8)
return (PIX *)ERROR_PTR("pixs must be 8 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixd = pixCreateTemplate(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
rotateAMGrayCornerLow(datad, w, h, wpld, datas, wpls, angle, grayval);
return pixd;
}
static void
rotateAMColorCornerLow(l_uint32 *datad,
l_int32 w,
l_int32 h,
l_int32 wpld,
l_uint32 *datas,
l_int32 wpls,
l_float32 angle,
l_uint32 colorval)
{
l_int32 i, j, wm2, hm2;
l_int32 xpm, ypm, xp, yp, xf, yf;
l_int32 rval, gval, bval;
l_uint32 word00, word01, word10, word11;
l_uint32 *lines, *lined;
l_float32 sina, cosa;
wm2 = w - 2;
hm2 = h - 2;
sina = 16. * sin(angle);
cosa = 16. * cos(angle);
for (i = 0; i < h; i++) {
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
xpm = (l_int32)(j * cosa + i * sina);
ypm = (l_int32)(i * cosa - j * sina);
xp = xpm >> 4;
yp = ypm >> 4;
xf = xpm & 0x0f;
yf = ypm & 0x0f;
/* if off the edge, write input colorval */
if (xp < 0 || yp < 0 || xp > wm2 || yp > hm2) {
*(lined + j) = colorval;
continue;
}
lines = datas + yp * wpls;
/* do area weighting. Without this, we would
* simply do:
* *(lined + j) = *(lines + xp);
* which is faster but gives lousy results!
*/
word00 = *(lines + xp);
word10 = *(lines + xp + 1);
word01 = *(lines + wpls + xp);
word11 = *(lines + wpls + xp + 1);
rval = ((16 - xf) * (16 - yf) * ((word00 >> L_RED_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_RED_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_RED_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_RED_SHIFT) & 0xff) + 128) / 256;
gval = ((16 - xf) * (16 - yf) * ((word00 >> L_GREEN_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_GREEN_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_GREEN_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_GREEN_SHIFT) & 0xff) + 128) / 256;
bval = ((16 - xf) * (16 - yf) * ((word00 >> L_BLUE_SHIFT) & 0xff) +
xf * (16 - yf) * ((word10 >> L_BLUE_SHIFT) & 0xff) +
(16 - xf) * yf * ((word01 >> L_BLUE_SHIFT) & 0xff) +
xf * yf * ((word11 >> L_BLUE_SHIFT) & 0xff) + 128) / 256;
composeRGBPixel(rval, gval, bval, lined + j);
}
}
}
static void
rotateAMGrayCornerLow(l_uint32 *datad,
l_int32 w,
l_int32 h,
l_int32 wpld,
l_uint32 *datas,
l_int32 wpls,
l_float32 angle,
l_uint8 grayval)
{
l_int32 i, j, wm2, hm2;
l_int32 xpm, ypm, xp, yp, xf, yf;
l_int32 v00, v01, v10, v11;
l_uint8 val;
l_uint32 *lines, *lined;
l_float32 sina, cosa;
wm2 = w - 2;
hm2 = h - 2;
sina = 16. * sin(angle);
cosa = 16. * cos(angle);
for (i = 0; i < h; i++) {
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
xpm = (l_int32)(j * cosa + i * sina);
ypm = (l_int32)(i * cosa - j * sina);
xp = xpm >> 4;
yp = ypm >> 4;
xf = xpm & 0x0f;
yf = ypm & 0x0f;
/* if off the edge, write input grayval */
if (xp < 0 || yp < 0 || xp > wm2 || yp > hm2) {
SET_DATA_BYTE(lined, j, grayval);
continue;
}
lines = datas + yp * wpls;
/* do area weighting. Without this, we would
* simply do:
* SET_DATA_BYTE(lined, j, GET_DATA_BYTE(lines, xp));
* which is faster but gives lousy results!
*/
v00 = (16 - xf) * (16 - yf) * GET_DATA_BYTE(lines, xp);
v10 = xf * (16 - yf) * GET_DATA_BYTE(lines, xp + 1);
v01 = (16 - xf) * yf * GET_DATA_BYTE(lines + wpls, xp);
v11 = xf * yf * GET_DATA_BYTE(lines + wpls, xp + 1);
val = (l_uint8)((v00 + v01 + v10 + v11 + 128) / 256);
SET_DATA_BYTE(lined, j, val);
}
}
}
/*------------------------------------------------------------------*
* Fast RGB color rotation about center *
*------------------------------------------------------------------*/
/*!
* \brief pixRotateAMColorFast()
*
* \param[in] pixs
* \param[in] angle radians; clockwise is positive
* \param[in] colorval e.g., 0 to bring in BLACK, 0xffffff00 for WHITE
* \return pixd, or NULL on error
*
*
* Notes:
* (1) This rotates a color image about the image center.
* (2) A positive angle gives a clockwise rotation.
* (3) It uses area mapping, dividing each pixel into
* 16 subpixels.
* (4) It is about 10% to 20% faster than the more accurate linear
* interpolation function pixRotateAMColor(),
* which uses 256 subpixels.
* (5) For some reason it shifts the image center.
* No attempt is made to rotate the alpha component.
*
*/
PIX *
pixRotateAMColorFast(PIX *pixs,
l_float32 angle,
l_uint32 colorval)
{
l_int32 w, h, wpls, wpld;
l_uint32 *datas, *datad;
PIX *pixd;
PROCNAME("pixRotateAMColorFast");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (pixGetDepth(pixs) != 32)
return (PIX *)ERROR_PTR("pixs must be 32 bpp", procName, NULL);
if (L_ABS(angle) < MinAngleToRotate)
return pixClone(pixs);
pixGetDimensions(pixs, &w, &h, NULL);
datas = pixGetData(pixs);
wpls = pixGetWpl(pixs);
pixd = pixCreateTemplate(pixs);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
rotateAMColorFastLow(datad, w, h, wpld, datas, wpls, angle, colorval);
return pixd;
}
/*!
* \brief rotateAMColorFastLow()
*
* This is a special simplification of area mapping with division
* of each pixel into 16 sub-pixels. The exact coefficients that
* should be used are the same as for the 4x linear interpolation
* scaling case, and are given there. I tried to approximate these
* as weighted coefficients with a maximum sum of 4, which
* allows us to do the arithmetic in parallel for the R, G and B
* components in a 32 bit pixel. However, there are three reasons
* for not doing that:
* (1) the loss of accuracy in the parallel implementation
* is visually significant
* (2) the parallel implementation (described below) is slower
* (3) the parallel implementation requires allocation of
* a temporary color image
*
* There are 16 cases for the choice of the subpixel, and
* for each, the mapping to the relevant source
* pixels is as follows:
*
* subpixel src pixel weights
* -------- -----------------
* 0 sp1
* 1 (3 * sp1 + sp2) / 4
* 2 (sp1 + sp2) / 2
* 3 (sp1 + 3 * sp2) / 4
* 4 (3 * sp1 + sp3) / 4
* 5 (9 * sp1 + 3 * sp2 + 3 * sp3 + sp4) / 16
* 6 (3 * sp1 + 3 * sp2 + sp3 + sp4) / 8
* 7 (3 * sp1 + 9 * sp2 + sp3 + 3 * sp4) / 16
* 8 (sp1 + sp3) / 2
* 9 (3 * sp1 + sp2 + 3 * sp3 + sp4) / 8
* 10 (sp1 + sp2 + sp3 + sp4) / 4
* 11 (sp1 + 3 * sp2 + sp3 + 3 * sp4) / 8
* 12 (sp1 + 3 * sp3) / 4
* 13 (3 * sp1 + sp2 + 9 * sp3 + 3 * sp4) / 16
* 14 (sp1 + sp2 + 3 * sp3 + 3 * sp4) / 8
* 15 (sp1 + 3 * sp2 + 3 * sp3 + 9 * sp4) / 16
*
* Another way to visualize this is to consider the area mapping
* (or linear interpolation) coefficients for the pixel sp1.
* Expressed in fourths, they can be written as asymmetric matrix:
*
* 4 3 2 1
* 3 2.25 1.5 0.75
* 2 1.5 1 0.5
* 1 0.75 0.5 0.25
*
* The coefficients for the three neighboring pixels can be
* similarly written.
*
* This is implemented here, where, for each color component,
* we inline its extraction from each participating word,
* construct the linear combination, and combine the results
* into the destination 32 bit RGB pixel, using the appropriate shifts.
*
* It is interesting to note that an alternative method, where
* we do the arithmetic on the 32 bit pixels directly (after
* shifting the components so they won't overflow into each other)
* is significantly inferior. Because we have only 8 bits for
* internal overflows, which can be distributed as 2, 3, 3, it
* is impossible to add these with the correct linear
* interpolation coefficients, which require a sum of up to 16.
* Rounding off to a sum of 4 causes appreciable visual artifacts
* in the rotated image. The code for the inferior method
* can be found in prog/rotatefastalt.c, for reference.
*/
static void
rotateAMColorFastLow(l_uint32 *datad,
l_int32 w,
l_int32 h,
l_int32 wpld,
l_uint32 *datas,
l_int32 wpls,
l_float32 angle,
l_uint32 colorval)
{
l_int32 i, j, xcen, ycen, wm2, hm2;
l_int32 xdif, ydif, xpm, ypm, xp, yp, xf, yf;
l_uint32 word1, word2, word3, word4, red, blue, green;
l_uint32 *pword, *lines, *lined;
l_float32 sina, cosa;
xcen = w / 2;
wm2 = w - 2;
ycen = h / 2;
hm2 = h - 2;
sina = 4. * sin(angle);
cosa = 4. * cos(angle);
for (i = 0; i < h; i++) {
ydif = ycen - i;
lined = datad + i * wpld;
for (j = 0; j < w; j++) {
xdif = xcen - j;
xpm = (l_int32)(-xdif * cosa - ydif * sina);
ypm = (l_int32)(-ydif * cosa + xdif * sina);
xp = xcen + (xpm >> 2);
yp = ycen + (ypm >> 2);
xf = xpm & 0x03;
yf = ypm & 0x03;
/* if off the edge, write input grayval */
if (xp < 0 || yp < 0 || xp > wm2 || yp > hm2) {
*(lined + j) = colorval;
continue;
}
lines = datas + yp * wpls;
pword = lines + xp;
switch (xf + 4 * yf)
{
case 0:
*(lined + j) = *pword;
break;
case 1:
word1 = *pword;
word2 = *(pword + 1);
red = 3 * (word1 >> 24) + (word2 >> 24);
green = 3 * ((word1 >> 16) & 0xff) +
((word2 >> 16) & 0xff);
blue = 3 * ((word1 >> 8) & 0xff) +
((word2 >> 8) & 0xff);
*(lined + j) = ((red << 22) & 0xff000000) |
((green << 14) & 0x00ff0000) |
((blue << 6) & 0x0000ff00);
break;
case 2:
word1 = *pword;
word2 = *(pword + 1);
red = (word1 >> 24) + (word2 >> 24);
green = ((word1 >> 16) & 0xff) + ((word2 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + ((word2 >> 8) & 0xff);
*(lined + j) = ((red << 23) & 0xff000000) |
((green << 15) & 0x00ff0000) |
((blue << 7) & 0x0000ff00);
break;
case 3:
word1 = *pword;
word2 = *(pword + 1);
red = (word1 >> 24) + 3 * (word2 >> 24);
green = ((word1 >> 16) & 0xff) +
3 * ((word2 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) +
3 * ((word2 >> 8) & 0xff);
*(lined + j) = ((red << 22) & 0xff000000) |
((green << 14) & 0x00ff0000) |
((blue << 6) & 0x0000ff00);
break;
case 4:
word1 = *pword;
word3 = *(pword + wpls);
red = 3 * (word1 >> 24) + (word3 >> 24);
green = 3 * ((word1 >> 16) & 0xff) +
((word3 >> 16) & 0xff);
blue = 3 * ((word1 >> 8) & 0xff) +
((word3 >> 8) & 0xff);
*(lined + j) = ((red << 22) & 0xff000000) |
((green << 14) & 0x00ff0000) |
((blue << 6) & 0x0000ff00);
break;
case 5:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = 9 * (word1 >> 24) + 3 * (word2 >> 24) +
3 * (word3 >> 24) + (word4 >> 24);
green = 9 * ((word1 >> 16) & 0xff) +
3 * ((word2 >> 16) & 0xff) +
3 * ((word3 >> 16) & 0xff) +
((word4 >> 16) & 0xff);
blue = 9 * ((word1 >> 8) & 0xff) +
3 * ((word2 >> 8) & 0xff) +
3 * ((word3 >> 8) & 0xff) +
((word4 >> 8) & 0xff);
*(lined + j) = ((red << 20) & 0xff000000) |
((green << 12) & 0x00ff0000) |
((blue << 4) & 0x0000ff00);
break;
case 6:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = 3 * (word1 >> 24) + 3 * (word2 >> 24) +
(word3 >> 24) + (word4 >> 24);
green = 3 * ((word1 >> 16) & 0xff) +
3 * ((word2 >> 16) & 0xff) +
((word3 >> 16) & 0xff) +
((word4 >> 16) & 0xff);
blue = 3 * ((word1 >> 8) & 0xff) +
3 * ((word2 >> 8) & 0xff) +
((word3 >> 8) & 0xff) +
((word4 >> 8) & 0xff);
*(lined + j) = ((red << 21) & 0xff000000) |
((green << 13) & 0x00ff0000) |
((blue << 5) & 0x0000ff00);
break;
case 7:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = 3 * (word1 >> 24) + 9 * (word2 >> 24) +
(word3 >> 24) + 3 * (word4 >> 24);
green = 3 * ((word1 >> 16) & 0xff) +
9 * ((word2 >> 16) & 0xff) +
((word3 >> 16) & 0xff) +
3 * ((word4 >> 16) & 0xff);
blue = 3 * ((word1 >> 8) & 0xff) +
9 * ((word2 >> 8) & 0xff) +
((word3 >> 8) & 0xff) +
3 * ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 20) & 0xff000000) |
((green << 12) & 0x00ff0000) |
((blue << 4) & 0x0000ff00);
break;
case 8:
word1 = *pword;
word3 = *(pword + wpls);
red = (word1 >> 24) + (word3 >> 24);
green = ((word1 >> 16) & 0xff) + ((word3 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + ((word3 >> 8) & 0xff);
*(lined + j) = ((red << 23) & 0xff000000) |
((green << 15) & 0x00ff0000) |
((blue << 7) & 0x0000ff00);
break;
case 9:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = 3 * (word1 >> 24) + (word2 >> 24) +
3 * (word3 >> 24) + (word4 >> 24);
green = 3 * ((word1 >> 16) & 0xff) + ((word2 >> 16) & 0xff) +
3 * ((word3 >> 16) & 0xff) + ((word4 >> 16) & 0xff);
blue = 3 * ((word1 >> 8) & 0xff) + ((word2 >> 8) & 0xff) +
3 * ((word3 >> 8) & 0xff) + ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 21) & 0xff000000) |
((green << 13) & 0x00ff0000) |
((blue << 5) & 0x0000ff00);
break;
case 10:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = (word1 >> 24) + (word2 >> 24) +
(word3 >> 24) + (word4 >> 24);
green = ((word1 >> 16) & 0xff) + ((word2 >> 16) & 0xff) +
((word3 >> 16) & 0xff) + ((word4 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + ((word2 >> 8) & 0xff) +
((word3 >> 8) & 0xff) + ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 22) & 0xff000000) |
((green << 14) & 0x00ff0000) |
((blue << 6) & 0x0000ff00);
break;
case 11:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = (word1 >> 24) + 3 * (word2 >> 24) +
(word3 >> 24) + 3 * (word4 >> 24);
green = ((word1 >> 16) & 0xff) + 3 * ((word2 >> 16) & 0xff) +
((word3 >> 16) & 0xff) + 3 * ((word4 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + 3 * ((word2 >> 8) & 0xff) +
((word3 >> 8) & 0xff) + 3 * ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 21) & 0xff000000) |
((green << 13) & 0x00ff0000) |
((blue << 5) & 0x0000ff00);
break;
case 12:
word1 = *pword;
word3 = *(pword + wpls);
red = (word1 >> 24) + 3 * (word3 >> 24);
green = ((word1 >> 16) & 0xff) +
3 * ((word3 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) +
3 * ((word3 >> 8) & 0xff);
*(lined + j) = ((red << 22) & 0xff000000) |
((green << 14) & 0x00ff0000) |
((blue << 6) & 0x0000ff00);
break;
case 13:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = 3 * (word1 >> 24) + (word2 >> 24) +
9 * (word3 >> 24) + 3 * (word4 >> 24);
green = 3 * ((word1 >> 16) & 0xff) + ((word2 >> 16) & 0xff) +
9 * ((word3 >> 16) & 0xff) + 3 * ((word4 >> 16) & 0xff);
blue = 3 *((word1 >> 8) & 0xff) + ((word2 >> 8) & 0xff) +
9 * ((word3 >> 8) & 0xff) + 3 * ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 20) & 0xff000000) |
((green << 12) & 0x00ff0000) |
((blue << 4) & 0x0000ff00);
break;
case 14:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = (word1 >> 24) + (word2 >> 24) +
3 * (word3 >> 24) + 3 * (word4 >> 24);
green = ((word1 >> 16) & 0xff) +((word2 >> 16) & 0xff) +
3 * ((word3 >> 16) & 0xff) + 3 * ((word4 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + ((word2 >> 8) & 0xff) +
3 * ((word3 >> 8) & 0xff) + 3 * ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 21) & 0xff000000) |
((green << 13) & 0x00ff0000) |
((blue << 5) & 0x0000ff00);
break;
case 15:
word1 = *pword;
word2 = *(pword + 1);
word3 = *(pword + wpls);
word4 = *(pword + wpls + 1);
red = (word1 >> 24) + 3 * (word2 >> 24) +
3 * (word3 >> 24) + 9 * (word4 >> 24);
green = ((word1 >> 16) & 0xff) + 3 * ((word2 >> 16) & 0xff) +
3 * ((word3 >> 16) & 0xff) + 9 * ((word4 >> 16) & 0xff);
blue = ((word1 >> 8) & 0xff) + 3 * ((word2 >> 8) & 0xff) +
3 * ((word3 >> 8) & 0xff) + 9 * ((word4 >> 8) & 0xff);
*(lined + j) = ((red << 20) & 0xff000000) |
((green << 12) & 0x00ff0000) |
((blue << 4) & 0x0000ff00);
break;
default:
lept_stderr("shouldn't get here\n");
break;
}
}
}
}