* jdcolor.c
*
* Copyright (C) 1991-1997, Thomas G. Lane.
- * Modified 2011-2012 by Guido Vollbeding.
+ * Modified 2011-2013 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.
*
typedef struct {
struct jpeg_color_deconverter pub; /* public fields */
- /* Private state for YCC->RGB conversion */
+ /* 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 */
+ JSAMPLE * range_limit; /* pointer to normal sample range limit table, */
+ /* or extended sample range limit table for BG_YCC */
+
/* Private state for RGB->Y conversion */
INT32 * rgb_y_tab; /* => table for RGB to Y conversion */
} my_color_deconverter;
typedef my_color_deconverter * my_cconvert_ptr;
-/**************** YCbCr -> RGB conversion: most common case **************/
-/**************** RGB -> Y conversion: less common case **************/
+/*************** YCbCr -> RGB conversion: most common case **************/
+/*************** BG_YCC -> RGB conversion: less common case **************/
+/*************** RGB -> Y conversion: less common case **************/
/*
- * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
- * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
- * The conversion equations to be implemented are therefore
+ * 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
*
- * R = Y + 1.40200 * Cr
- * G = Y - 0.34414 * Cb - 0.71414 * Cr
- * B = Y + 1.77200 * Cb
+ * 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
*
- * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
+ * 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.
- * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
+ * 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
* 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 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.
+ * 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.
/*
- * Initialize tables for YCC->RGB colorspace conversion.
+ * 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));
+
+ cconvert->range_limit = cinfo->sample_range_limit;
+
+ 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)
+ RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS);
+ /* Cb=>B value is nearest int to 1.772 * x */
+ cconvert->Cb_b_tab[i] = (int)
+ RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, 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;
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
(MAXJSAMPLE+1) * SIZEOF(INT32));
+ cconvert->range_limit = (JSAMPLE *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ 5 * (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
+
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 1.40200 * x */
+ /* Cr=>R value is nearest int to 2.804 * x */
cconvert->Cr_r_tab[i] = (int)
- RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
- /* Cb=>B value is nearest int to 1.77200 * x */
+ RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS);
+ /* Cb=>B value is nearest int to 3.544 * x */
cconvert->Cb_b_tab[i] = (int)
- RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
- /* Cr=>G value is scaled-up -0.71414 * x */
- cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x;
- /* Cb=>G value is scaled-up -0.34414 * x */
+ RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, 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(0.34414)) * x + ONE_HALF;
+ cconvert->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
}
+
+ /* Cb and Cr portions can extend to double range in wide gamut case,
+ * so we prepare an appropriate extended range limit table.
+ */
+
+ /* First segment of range limit table: limit[x] = 0 for x < 0 */
+ MEMZERO(cconvert->range_limit, 2 * (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
+ cconvert->range_limit += 2 * (MAXJSAMPLE+1);
+ /* Main part of range limit table: limit[x] = x */
+ for (i = 0; i <= MAXJSAMPLE; i++)
+ cconvert->range_limit[i] = (JSAMPLE) i;
+ /* End of range limit table: limit[x] = MAXJSAMPLE for x > MAXJSAMPLE */
+ for (; i < 3 * (MAXJSAMPLE+1); i++)
+ cconvert->range_limit[i] = MAXJSAMPLE;
}
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 JSAMPLE * range_limit = cconvert->range_limit;
register int * Crrtab = cconvert->Cr_r_tab;
register int * Cbbtab = cconvert->Cb_b_tab;
register INT32 * Crgtab = cconvert->Cr_g_tab;
y = GETJSAMPLE(inptr0[col]);
cb = GETJSAMPLE(inptr1[col]);
cr = GETJSAMPLE(inptr2[col]);
- /* Range-limiting is essential due to noise introduced by DCT losses. */
- outptr[RGB_RED] = range_limit[y + Crrtab[cr]];
+ /* 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_BLUE] = range_limit[y + Cbbtab[cb]];
outptr += RGB_PIXELSIZE;
}
}
}
-/**************** Cases other than YCbCr -> RGB **************/
+/**************** Cases other than YCC -> RGB ****************/
/*
(TABLE_SIZE * SIZEOF(INT32)));
for (i = 0; i <= MAXJSAMPLE; i++) {
- rgb_y_tab[i+R_Y_OFF] = FIX(0.29900) * i;
- rgb_y_tab[i+G_Y_OFF] = FIX(0.58700) * i;
- rgb_y_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF;
+ rgb_y_tab[i+R_Y_OFF] = FIX(0.299) * i;
+ rgb_y_tab[i+G_Y_OFF] = FIX(0.587) * i;
+ rgb_y_tab[i+B_Y_OFF] = FIX(0.114) * i + ONE_HALF;
}
}
/*
* [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)
/*
* Color conversion for grayscale: just copy the data.
- * This also works for YCbCr -> grayscale conversion, in which
+ * This also works for YCC -> grayscale conversion, in which
* we just copy the Y (luminance) component and ignore chrominance.
*/
y = GETJSAMPLE(inptr0[col]);
cb = GETJSAMPLE(inptr1[col]);
cr = GETJSAMPLE(inptr2[col]);
- /* Range-limiting is essential due to noise introduced by DCT losses. */
+ /* 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],
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;
break;
}
- /* Support color transform only for RGB colorspace */
- if (cinfo->color_transform && cinfo->jpeg_color_space != JCS_RGB)
+ /* 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.
switch (cinfo->out_color_space) {
case JCS_GRAYSCALE:
cinfo->out_color_components = 1;
- if (cinfo->jpeg_color_space == JCS_GRAYSCALE ||
- cinfo->jpeg_color_space == JCS_YCbCr) {
+ 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;
- } else if (cinfo->jpeg_color_space == JCS_RGB) {
+ break;
+ case JCS_RGB:
switch (cinfo->color_transform) {
case JCT_NONE:
cconvert->pub.color_convert = rgb_gray_convert;
break;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
- break;
}
build_rgb_y_table(cinfo);
- } else
+ break;
+ default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ }
break;
case JCS_RGB:
cinfo->out_color_components = RGB_PIXELSIZE;
- if (cinfo->jpeg_color_space == JCS_YCbCr) {
+ 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);
- } else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) {
- cconvert->pub.color_convert = gray_rgb_convert;
- } else if (cinfo->jpeg_color_space == JCS_RGB) {
+ 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;
default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ }
+ break;
+ default:
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ }
+ break;
+
+ case JCS_BG_RGB:
+ cinfo->out_color_components = RGB_PIXELSIZE;
+ if (cinfo->jpeg_color_space == JCS_BG_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);
}
} else
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
case JCS_CMYK:
cinfo->out_color_components = 4;
- if (cinfo->jpeg_color_space == JCS_YCCK) {
+ switch (cinfo->jpeg_color_space) {
+ case JCS_YCCK:
cconvert->pub.color_convert = ycck_cmyk_convert;
build_ycc_rgb_table(cinfo);
- } else if (cinfo->jpeg_color_space == JCS_CMYK) {
+ break;
+ case JCS_CMYK:
cconvert->pub.color_convert = null_convert;
- } else
+ break;
+ default:
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ }
break;
default:
projects / reactos.git / blobdiff