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opencv/3rdparty/libjpeg/jdcolor.c

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/*
* jdcolor.c
*
* Copyright (C) 1991-1997, Thomas G. Lane.
* Modified 2011-2023 by Guido Vollbeding.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains output colorspace conversion routines.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#if RANGE_BITS < 2
/* Deliberate syntax err */
Sorry, this code requires 2 or more range extension bits.
#endif
/* Private subobject */
typedef struct {
struct jpeg_color_deconverter pub; /* public fields */
/* Private state for YCbCr->RGB and BG_YCC->RGB conversion */
int * Cr_r_tab; /* => table for Cr to R conversion */
int * Cb_b_tab; /* => table for Cb to B conversion */
INT32 * Cr_g_tab; /* => table for Cr to G conversion */
INT32 * Cb_g_tab; /* => table for Cb to G conversion */
/* Private state for RGB->Y conversion */
INT32 * R_y_tab; /* => table for R to Y conversion */
INT32 * G_y_tab; /* => table for G to Y conversion */
INT32 * B_y_tab; /* => table for B to Y conversion */
} my_color_deconverter;
typedef my_color_deconverter * my_cconvert_ptr;
/*************** YCbCr -> RGB conversion: most common case **************/
/*************** BG_YCC -> RGB conversion: less common case **************/
/*************** RGB -> Y conversion: less common case **************/
/*
* YCbCr is defined per Recommendation ITU-R BT.601-7 (03/2011),
* previously known as Recommendation CCIR 601-1, except that Cb and Cr
* are normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
* sRGB (standard RGB color space) is defined per IEC 61966-2-1:1999.
* sYCC (standard luma-chroma-chroma color space with extended gamut)
* is defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex F.
* bg-sRGB and bg-sYCC (big gamut standard color spaces)
* are defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex G.
* Note that the derived conversion coefficients given in some of these
* documents are imprecise. The general conversion equations are
*
* R = Y + K * (1 - Kr) * Cr
* G = Y - K * (Kb * (1 - Kb) * Cb + Kr * (1 - Kr) * Cr) / (1 - Kr - Kb)
* B = Y + K * (1 - Kb) * Cb
*
* Y = Kr * R + (1 - Kr - Kb) * G + Kb * B
*
* With Kr = 0.299 and Kb = 0.114 (derived according to SMPTE RP 177-1993
* from the 1953 FCC NTSC primaries and CIE Illuminant C), K = 2 for sYCC,
* the conversion equations to be implemented are therefore
*
* R = Y + 1.402 * Cr
* G = Y - 0.344136286 * Cb - 0.714136286 * Cr
* B = Y + 1.772 * Cb
*
* Y = 0.299 * R + 0.587 * G + 0.114 * B
*
* where Cb and Cr represent the incoming values less CENTERJSAMPLE.
* For bg-sYCC, with K = 4, the equations are
*
* R = Y + 2.804 * Cr
* G = Y - 0.688272572 * Cb - 1.428272572 * Cr
* B = Y + 3.544 * Cb
*
* To avoid floating-point arithmetic, we represent the fractional constants
* as integers scaled up by 2^16 (about 4 digits precision); we have to divide
* the products by 2^16, with appropriate rounding, to get the correct answer.
* Notice that Y, being an integral input, does not contribute any fraction
* so it need not participate in the rounding.
*
* For even more speed, we avoid doing any multiplications in the inner loop
* by precalculating the constants times Cb and Cr for all possible values.
* For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
* for 9-bit to 12-bit samples it is still acceptable. It's not very
* reasonable for 16-bit samples, but if you want lossless storage
* you shouldn't be changing colorspace anyway.
* The Cr=>R and Cb=>B values can be rounded to integers in advance;
* the values for the G calculation are left scaled up,
* since we must add them together before rounding.
*/
#define SCALEBITS 16 /* speediest right-shift on some machines */
#define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
/*
* Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
*/
LOCAL(void)
build_ycc_rgb_table (j_decompress_ptr cinfo)
/* Normal case, sYCC */
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
int i;
INT32 x;
SHIFT_TEMPS
cconvert->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
cconvert->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
cconvert->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
cconvert->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
/* Cr=>R value is nearest int to 1.402 * x */
cconvert->Cr_r_tab[i] = (int) DESCALE(FIX(1.402) * x, SCALEBITS);
/* Cb=>B value is nearest int to 1.772 * x */
cconvert->Cb_b_tab[i] = (int) DESCALE(FIX(1.772) * x, SCALEBITS);
/* Cr=>G value is scaled-up -0.714136286 * x */
cconvert->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
/* Cb=>G value is scaled-up -0.344136286 * x */
/* We also add in ONE_HALF so that need not do it in inner loop */
cconvert->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
}
}
LOCAL(void)
build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
/* Wide gamut case, bg-sYCC */
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
int i;
INT32 x;
SHIFT_TEMPS
cconvert->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
cconvert->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
cconvert->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
cconvert->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
/* Cr=>R value is nearest int to 2.804 * x */
cconvert->Cr_r_tab[i] = (int) DESCALE(FIX(2.804) * x, SCALEBITS);
/* Cb=>B value is nearest int to 3.544 * x */
cconvert->Cb_b_tab[i] = (int) DESCALE(FIX(3.544) * x, SCALEBITS);
/* Cr=>G value is scaled-up -1.428272572 * x */
cconvert->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
/* Cb=>G value is scaled-up -0.688272572 * x */
/* We also add in ONE_HALF so that need not do it in inner loop */
cconvert->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
}
}
/*
* Convert some rows of samples to the output colorspace.
*
* Note that we change from noninterleaved, one-plane-per-component format
* to interleaved-pixel format. The output buffer is therefore three times
* as wide as the input buffer.
*
* A starting row offset is provided only for the input buffer. The caller
* can easily adjust the passed output_buf value to accommodate any row
* offset required on that side.
*/
METHODDEF(void)
ycc_rgb_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
register int y, cb, cr;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
/* copy these pointers into registers if possible */
register JSAMPLE * range_limit = cinfo->sample_range_limit;
register int * Crrtab = cconvert->Cr_r_tab;
register int * Cbbtab = cconvert->Cb_b_tab;
register INT32 * Crgtab = cconvert->Cr_g_tab;
register INT32 * Cbgtab = cconvert->Cb_g_tab;
SHIFT_TEMPS
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
y = GETJSAMPLE(inptr0[col]);
cb = GETJSAMPLE(inptr1[col]);
cr = GETJSAMPLE(inptr2[col]);
/* Range-limiting is essential due to noise introduced by DCT losses,
* for extended gamut (sYCC) and wide gamut (bg-sYCC) encodings.
*/
outptr[RGB_RED] = range_limit[y + Crrtab[cr]];
outptr[RGB_GREEN] = range_limit[y +
((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
SCALEBITS))];
outptr[RGB_BLUE] = range_limit[y + Cbbtab[cb]];
outptr += RGB_PIXELSIZE;
}
}
}
/**************** Cases other than YCC -> RGB ****************/
/*
* Initialize for RGB->grayscale colorspace conversion.
*/
LOCAL(void)
build_rgb_y_table (j_decompress_ptr cinfo)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
INT32 i;
cconvert->R_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
cconvert->G_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
cconvert->B_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
for (i = 0; i <= MAXJSAMPLE; i++) {
cconvert->R_y_tab[i] = FIX(0.299) * i;
cconvert->G_y_tab[i] = FIX(0.587) * i;
cconvert->B_y_tab[i] = FIX(0.114) * i + ONE_HALF;
}
}
/*
* Convert RGB to grayscale.
*/
METHODDEF(void)
rgb_gray_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
register INT32 y;
register INT32 * Rytab = cconvert->R_y_tab;
register INT32 * Gytab = cconvert->G_y_tab;
register INT32 * Bytab = cconvert->B_y_tab;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
y = Rytab[GETJSAMPLE(inptr0[col])];
y += Gytab[GETJSAMPLE(inptr1[col])];
y += Bytab[GETJSAMPLE(inptr2[col])];
outptr[col] = (JSAMPLE) (y >> SCALEBITS);
}
}
}
/*
* Convert some rows of samples to the output colorspace.
* [R-G,G,B-G] to [R,G,B] conversion with modulo calculation
* (inverse color transform).
* This can be seen as an adaption of the general YCbCr->RGB
* conversion equation with Kr = Kb = 0, while replacing the
* normalization by modulo calculation.
*/
METHODDEF(void)
rgb1_rgb_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
register int r, g, b;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
r = GETJSAMPLE(inptr0[col]);
g = GETJSAMPLE(inptr1[col]);
b = GETJSAMPLE(inptr2[col]);
/* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
* (modulo) operator is equivalent to the bitmask operator AND.
*/
outptr[RGB_RED] = (JSAMPLE) ((r + g - CENTERJSAMPLE) & MAXJSAMPLE);
outptr[RGB_GREEN] = (JSAMPLE) g;
outptr[RGB_BLUE] = (JSAMPLE) ((b + g - CENTERJSAMPLE) & MAXJSAMPLE);
outptr += RGB_PIXELSIZE;
}
}
}
/*
* [R-G,G,B-G] to grayscale conversion with modulo calculation
* (inverse color transform).
*/
METHODDEF(void)
rgb1_gray_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
register int r, g, b;
register INT32 y;
register INT32 * Rytab = cconvert->R_y_tab;
register INT32 * Gytab = cconvert->G_y_tab;
register INT32 * Bytab = cconvert->B_y_tab;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
r = GETJSAMPLE(inptr0[col]);
g = GETJSAMPLE(inptr1[col]);
b = GETJSAMPLE(inptr2[col]);
/* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
* (modulo) operator is equivalent to the bitmask operator AND.
*/
y = Rytab[(r + g - CENTERJSAMPLE) & MAXJSAMPLE];
y += Gytab[g];
y += Bytab[(b + g - CENTERJSAMPLE) & MAXJSAMPLE];
outptr[col] = (JSAMPLE) (y >> SCALEBITS);
}
}
}
/*
* Convert some rows of samples to the output colorspace.
* No colorspace change, but conversion from separate-planes
* to interleaved representation.
*/
METHODDEF(void)
rgb_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
/* We can dispense with GETJSAMPLE() here */
outptr[RGB_RED] = inptr0[col];
outptr[RGB_GREEN] = inptr1[col];
outptr[RGB_BLUE] = inptr2[col];
outptr += RGB_PIXELSIZE;
}
}
}
/*
* Color conversion for no colorspace change: just copy the data,
* converting from separate-planes to interleaved representation.
* Note: Omit uninteresting components in output buffer.
*/
METHODDEF(void)
null_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
register JSAMPROW outptr;
register JSAMPROW inptr;
register JDIMENSION count;
register int out_comps = cinfo->out_color_components;
JDIMENSION num_cols = cinfo->output_width;
JSAMPROW startptr;
int ci;
jpeg_component_info *compptr;
while (--num_rows >= 0) {
/* It seems fastest to make a separate pass for each component. */
startptr = *output_buf++;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
if (! compptr->component_needed)
continue; /* skip uninteresting component */
inptr = input_buf[ci][input_row];
outptr = startptr++;
for (count = num_cols; count > 0; count--) {
*outptr = *inptr++; /* don't need GETJSAMPLE() here */
outptr += out_comps;
}
}
input_row++;
}
}
/*
* Color conversion for grayscale: just copy the data.
* This also works for YCC -> grayscale conversion, in which
* we just copy the Y (luminance) component and ignore chrominance.
*/
METHODDEF(void)
grayscale_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
jcopy_sample_rows(input_buf[0] + input_row, output_buf,
num_rows, cinfo->output_width);
}
/*
* Convert grayscale to RGB: just duplicate the graylevel three times.
* This is provided to support applications that don't want to cope
* with grayscale as a separate case.
*/
METHODDEF(void)
gray_rgb_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
register JSAMPROW outptr;
register JSAMPROW inptr;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr = input_buf[0][input_row++];
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
/* We can dispense with GETJSAMPLE() here */
outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
outptr += RGB_PIXELSIZE;
}
}
}
/*
* Convert some rows of samples to the output colorspace.
* This version handles Adobe-style YCCK->CMYK conversion,
* where we convert YCbCr to R=1-C, G=1-M, and B=1-Y using the
* same conversion as above, while passing K (black) unchanged.
* We assume build_ycc_rgb_table has been called.
*/
METHODDEF(void)
ycck_cmyk_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
register int y, cb, cr;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2, inptr3;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
/* copy these pointers into registers if possible */
register JSAMPLE * range_limit = cinfo->sample_range_limit;
register int * Crrtab = cconvert->Cr_r_tab;
register int * Cbbtab = cconvert->Cb_b_tab;
register INT32 * Crgtab = cconvert->Cr_g_tab;
register INT32 * Cbgtab = cconvert->Cb_g_tab;
SHIFT_TEMPS
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
inptr3 = input_buf[3][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
y = GETJSAMPLE(inptr0[col]);
cb = GETJSAMPLE(inptr1[col]);
cr = GETJSAMPLE(inptr2[col]);
/* Range-limiting is essential due to noise introduced by DCT losses,
* and for extended gamut encodings (sYCC).
*/
outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])]; /* red */
outptr[1] = range_limit[MAXJSAMPLE - (y + /* green */
((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
SCALEBITS)))];
outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])]; /* blue */
/* K passes through unchanged */
outptr[3] = inptr3[col]; /* don't need GETJSAMPLE here */
outptr += 4;
}
}
}
/*
* Convert CMYK to YK part of YCCK for colorless output.
* We assume build_rgb_y_table has been called.
*/
METHODDEF(void)
cmyk_yk_convert (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION input_row,
JSAMPARRAY output_buf, int num_rows)
{
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
register INT32 y;
register INT32 * Rytab = cconvert->R_y_tab;
register INT32 * Gytab = cconvert->G_y_tab;
register INT32 * Bytab = cconvert->B_y_tab;
register JSAMPROW outptr;
register JSAMPROW inptr0, inptr1, inptr2, inptr3;
register JDIMENSION col;
JDIMENSION num_cols = cinfo->output_width;
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
inptr3 = input_buf[3][input_row];
input_row++;
outptr = *output_buf++;
for (col = 0; col < num_cols; col++) {
y = Rytab[MAXJSAMPLE - GETJSAMPLE(inptr0[col])];
y += Gytab[MAXJSAMPLE - GETJSAMPLE(inptr1[col])];
y += Bytab[MAXJSAMPLE - GETJSAMPLE(inptr2[col])];
outptr[0] = (JSAMPLE) (y >> SCALEBITS);
/* K passes through unchanged */
outptr[1] = inptr3[col]; /* don't need GETJSAMPLE here */
outptr += 2;
}
}
}
/*
* Empty method for start_pass.
*/
METHODDEF(void)
start_pass_dcolor (j_decompress_ptr cinfo)
{
/* no work needed */
}
/*
* Module initialization routine for output colorspace conversion.
*/
GLOBAL(void)
jinit_color_deconverter (j_decompress_ptr cinfo)
{
my_cconvert_ptr cconvert;
int ci, i;
cconvert = (my_cconvert_ptr) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_color_deconverter));
cinfo->cconvert = &cconvert->pub;
cconvert->pub.start_pass = start_pass_dcolor;
/* Make sure num_components agrees with jpeg_color_space */
switch (cinfo->jpeg_color_space) {
case JCS_GRAYSCALE:
if (cinfo->num_components != 1)
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
break;
case JCS_RGB:
case JCS_YCbCr:
case JCS_BG_RGB:
case JCS_BG_YCC:
if (cinfo->num_components != 3)
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
break;
case JCS_CMYK:
case JCS_YCCK:
if (cinfo->num_components != 4)
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
break;
default: /* JCS_UNKNOWN can be anything */
if (cinfo->num_components < 1)
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
}
/* Support color transform only for RGB colorspaces */
if (cinfo->color_transform &&
cinfo->jpeg_color_space != JCS_RGB &&
cinfo->jpeg_color_space != JCS_BG_RGB)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
/* Set out_color_components and conversion method based on requested space.
* Also adjust the component_needed flags for any unused components,
* so that earlier pipeline stages can avoid useless computation.
*/
switch (cinfo->out_color_space) {
case JCS_GRAYSCALE:
cinfo->out_color_components = 1;
switch (cinfo->jpeg_color_space) {
case JCS_GRAYSCALE:
case JCS_YCbCr:
case JCS_BG_YCC:
cconvert->pub.color_convert = grayscale_convert;
/* For color->grayscale conversion, only the Y (0) component is needed */
for (ci = 1; ci < cinfo->num_components; ci++)
cinfo->comp_info[ci].component_needed = FALSE;
break;
case JCS_RGB:
switch (cinfo->color_transform) {
case JCT_NONE:
cconvert->pub.color_convert = rgb_gray_convert;
break;
case JCT_SUBTRACT_GREEN:
cconvert->pub.color_convert = rgb1_gray_convert;
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
build_rgb_y_table(cinfo);
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
break;
case JCS_RGB:
cinfo->out_color_components = RGB_PIXELSIZE;
switch (cinfo->jpeg_color_space) {
case JCS_GRAYSCALE:
cconvert->pub.color_convert = gray_rgb_convert;
break;
case JCS_YCbCr:
cconvert->pub.color_convert = ycc_rgb_convert;
build_ycc_rgb_table(cinfo);
break;
case JCS_BG_YCC:
cconvert->pub.color_convert = ycc_rgb_convert;
build_bg_ycc_rgb_table(cinfo);
break;
case JCS_RGB:
switch (cinfo->color_transform) {
case JCT_NONE:
cconvert->pub.color_convert = rgb_convert;
break;
case JCT_SUBTRACT_GREEN:
cconvert->pub.color_convert = rgb1_rgb_convert;
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
break;
case JCS_BG_RGB:
if (cinfo->jpeg_color_space != JCS_BG_RGB)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
cinfo->out_color_components = RGB_PIXELSIZE;
switch (cinfo->color_transform) {
case JCT_NONE:
cconvert->pub.color_convert = rgb_convert;
break;
case JCT_SUBTRACT_GREEN:
cconvert->pub.color_convert = rgb1_rgb_convert;
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
break;
case JCS_CMYK:
if (cinfo->jpeg_color_space != JCS_YCCK)
goto def_label;
cinfo->out_color_components = 4;
cconvert->pub.color_convert = ycck_cmyk_convert;
build_ycc_rgb_table(cinfo);
break;
case JCS_YCCK:
if (cinfo->jpeg_color_space != JCS_CMYK ||
/* Support only YK part of YCCK for colorless output */
! cinfo->comp_info[0].component_needed ||
cinfo->comp_info[1].component_needed ||
cinfo->comp_info[2].component_needed ||
! cinfo->comp_info[3].component_needed)
goto def_label;
cinfo->out_color_components = 2;
/* Need all components on input side */
cinfo->comp_info[1].component_needed = TRUE;
cinfo->comp_info[2].component_needed = TRUE;
cconvert->pub.color_convert = cmyk_yk_convert;
build_rgb_y_table(cinfo);
break;
default: def_label: /* permit null conversion to same output space */
if (cinfo->out_color_space != cinfo->jpeg_color_space)
/* unsupported non-null conversion */
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
i = 0;
for (ci = 0; ci < cinfo->num_components; ci++)
if (cinfo->comp_info[ci].component_needed)
i++; /* count output color components */
cinfo->out_color_components = i;
cconvert->pub.color_convert = null_convert;
}
if (cinfo->quantize_colors)
cinfo->output_components = 1; /* single colormapped output component */
else
cinfo->output_components = cinfo->out_color_components;
}