--- /dev/null
+/*
+ * jccolor.c
+ *
+ * Copyright (C) 1991-1996, Thomas G. Lane.
+ * 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 input colorspace conversion routines.
+ */
+
+#define JPEG_INTERNALS
+#include "jinclude.h"
+#include "jpeglib.h"
+
+
+/* Private subobject */
+
+typedef struct {
+ struct jpeg_color_converter pub; /* public fields */
+
+ /* Private state for RGB->YCC conversion */
+ INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */
+} my_color_converter;
+
+typedef my_color_converter * my_cconvert_ptr;
+
+
+/**************** RGB -> YCbCr conversion: most 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
+ * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
+ * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
+ * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
+ * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
+ * Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2,
+ * rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and
+ * negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0)
+ * were not represented exactly. Now we sacrifice exact representation of
+ * maximum red and maximum blue in order to get exact grayscales.
+ *
+ * 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.
+ *
+ * For even more speed, we avoid doing any multiplications in the inner loop
+ * by precalculating the constants times R,G,B 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.
+ * The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included
+ * in the tables to save adding them separately in the inner loop.
+ */
+
+#define SCALEBITS 16 /* speediest right-shift on some machines */
+#define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS)
+#define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
+#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
+
+/* We allocate one big table and divide it up into eight parts, instead of
+ * doing eight alloc_small requests. This lets us use a single table base
+ * address, which can be held in a register in the inner loops on many
+ * machines (more than can hold all eight addresses, anyway).
+ */
+
+#define R_Y_OFF 0 /* offset to R => Y section */
+#define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
+#define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
+#define R_CB_OFF (3*(MAXJSAMPLE+1))
+#define G_CB_OFF (4*(MAXJSAMPLE+1))
+#define B_CB_OFF (5*(MAXJSAMPLE+1))
+#define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */
+#define G_CR_OFF (6*(MAXJSAMPLE+1))
+#define B_CR_OFF (7*(MAXJSAMPLE+1))
+#define TABLE_SIZE (8*(MAXJSAMPLE+1))
+
+
+/*
+ * Initialize for RGB->YCC colorspace conversion.
+ */
+
+METHODDEF(void)
+rgb_ycc_start (j_compress_ptr cinfo)
+{
+ my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+ INT32 * rgb_ycc_tab;
+ INT32 i;
+
+ /* Allocate and fill in the conversion tables. */
+ cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (TABLE_SIZE * SIZEOF(INT32)));
+
+ for (i = 0; i <= MAXJSAMPLE; i++) {
+ rgb_ycc_tab[i+R_Y_OFF] = FIX(0.29900) * i;
+ rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
+ rgb_ycc_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF;
+ rgb_ycc_tab[i+R_CB_OFF] = (-FIX(0.16874)) * i;
+ rgb_ycc_tab[i+G_CB_OFF] = (-FIX(0.33126)) * i;
+ /* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr.
+ * This ensures that the maximum output will round to MAXJSAMPLE
+ * not MAXJSAMPLE+1, and thus that we don't have to range-limit.
+ */
+ rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
+/* B=>Cb and R=>Cr tables are the same
+ rgb_ycc_tab[i+R_CR_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
+*/
+ rgb_ycc_tab[i+G_CR_OFF] = (-FIX(0.41869)) * i;
+ rgb_ycc_tab[i+B_CR_OFF] = (-FIX(0.08131)) * i;
+ }
+}
+
+
+/*
+ * Convert some rows of samples to the JPEG colorspace.
+ *
+ * Note that we change from the application's interleaved-pixel format
+ * to our internal noninterleaved, one-plane-per-component format.
+ * The input buffer is therefore three times as wide as the output buffer.
+ *
+ * A starting row offset is provided only for the output buffer. The caller
+ * can easily adjust the passed input_buf value to accommodate any row
+ * offset required on that side.
+ */
+
+METHODDEF(void)
+rgb_ycc_convert (j_compress_ptr cinfo,
+ JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+ JDIMENSION output_row, int num_rows)
+{
+ my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+ register int r, g, b;
+ register INT32 * ctab = cconvert->rgb_ycc_tab;
+ register JSAMPROW inptr;
+ register JSAMPROW outptr0, outptr1, outptr2;
+ register JDIMENSION col;
+ JDIMENSION num_cols = cinfo->image_width;
+
+ while (--num_rows >= 0) {
+ inptr = *input_buf++;
+ outptr0 = output_buf[0][output_row];
+ outptr1 = output_buf[1][output_row];
+ outptr2 = output_buf[2][output_row];
+ output_row++;
+ for (col = 0; col < num_cols; col++) {
+ r = GETJSAMPLE(inptr[RGB_RED]);
+ g = GETJSAMPLE(inptr[RGB_GREEN]);
+ b = GETJSAMPLE(inptr[RGB_BLUE]);
+ inptr += RGB_PIXELSIZE;
+ /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
+ * must be too; we do not need an explicit range-limiting operation.
+ * Hence the value being shifted is never negative, and we don't
+ * need the general RIGHT_SHIFT macro.
+ */
+ /* Y */
+ outptr0[col] = (JSAMPLE)
+ ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+ >> SCALEBITS);
+ /* Cb */
+ outptr1[col] = (JSAMPLE)
+ ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
+ >> SCALEBITS);
+ /* Cr */
+ outptr2[col] = (JSAMPLE)
+ ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
+ >> SCALEBITS);
+ }
+ }
+}
+
+
+/**************** Cases other than RGB -> YCbCr **************/
+
+
+/*
+ * Convert some rows of samples to the JPEG colorspace.
+ * This version handles RGB->grayscale conversion, which is the same
+ * as the RGB->Y portion of RGB->YCbCr.
+ * We assume rgb_ycc_start has been called (we only use the Y tables).
+ */
+
+METHODDEF(void)
+rgb_gray_convert (j_compress_ptr cinfo,
+ JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+ JDIMENSION output_row, int num_rows)
+{
+ my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+ register int r, g, b;
+ register INT32 * ctab = cconvert->rgb_ycc_tab;
+ register JSAMPROW inptr;
+ register JSAMPROW outptr;
+ register JDIMENSION col;
+ JDIMENSION num_cols = cinfo->image_width;
+
+ while (--num_rows >= 0) {
+ inptr = *input_buf++;
+ outptr = output_buf[0][output_row];
+ output_row++;
+ for (col = 0; col < num_cols; col++) {
+ r = GETJSAMPLE(inptr[RGB_RED]);
+ g = GETJSAMPLE(inptr[RGB_GREEN]);
+ b = GETJSAMPLE(inptr[RGB_BLUE]);
+ inptr += RGB_PIXELSIZE;
+ /* Y */
+ outptr[col] = (JSAMPLE)
+ ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+ >> SCALEBITS);
+ }
+ }
+}
+
+
+/*
+ * Convert some rows of samples to the JPEG colorspace.
+ * This version handles Adobe-style CMYK->YCCK conversion,
+ * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same
+ * conversion as above, while passing K (black) unchanged.
+ * We assume rgb_ycc_start has been called.
+ */
+
+METHODDEF(void)
+cmyk_ycck_convert (j_compress_ptr cinfo,
+ JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+ JDIMENSION output_row, int num_rows)
+{
+ my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+ register int r, g, b;
+ register INT32 * ctab = cconvert->rgb_ycc_tab;
+ register JSAMPROW inptr;
+ register JSAMPROW outptr0, outptr1, outptr2, outptr3;
+ register JDIMENSION col;
+ JDIMENSION num_cols = cinfo->image_width;
+
+ while (--num_rows >= 0) {
+ inptr = *input_buf++;
+ outptr0 = output_buf[0][output_row];
+ outptr1 = output_buf[1][output_row];
+ outptr2 = output_buf[2][output_row];
+ outptr3 = output_buf[3][output_row];
+ output_row++;
+ for (col = 0; col < num_cols; col++) {
+ r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
+ g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
+ b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
+ /* K passes through as-is */
+ outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */
+ inptr += 4;
+ /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
+ * must be too; we do not need an explicit range-limiting operation.
+ * Hence the value being shifted is never negative, and we don't
+ * need the general RIGHT_SHIFT macro.
+ */
+ /* Y */
+ outptr0[col] = (JSAMPLE)
+ ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+ >> SCALEBITS);
+ /* Cb */
+ outptr1[col] = (JSAMPLE)
+ ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
+ >> SCALEBITS);
+ /* Cr */
+ outptr2[col] = (JSAMPLE)
+ ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
+ >> SCALEBITS);
+ }
+ }
+}
+
+
+/*
+ * Convert some rows of samples to the JPEG colorspace.
+ * This version handles grayscale output with no conversion.
+ * The source can be either plain grayscale or YCbCr (since Y == gray).
+ */
+
+METHODDEF(void)
+grayscale_convert (j_compress_ptr cinfo,
+ JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+ JDIMENSION output_row, int num_rows)
+{
+ register JSAMPROW inptr;
+ register JSAMPROW outptr;
+ register JDIMENSION col;
+ JDIMENSION num_cols = cinfo->image_width;
+ int instride = cinfo->input_components;
+
+ while (--num_rows >= 0) {
+ inptr = *input_buf++;
+ outptr = output_buf[0][output_row];
+ output_row++;
+ for (col = 0; col < num_cols; col++) {
+ outptr[col] = inptr[0]; /* don't need GETJSAMPLE() here */
+ inptr += instride;
+ }
+ }
+}
+
+
+/*
+ * Convert some rows of samples to the JPEG colorspace.
+ * This version handles multi-component colorspaces without conversion.
+ * We assume input_components == num_components.
+ */
+
+METHODDEF(void)
+null_convert (j_compress_ptr cinfo,
+ JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
+ JDIMENSION output_row, int num_rows)
+{
+ register JSAMPROW inptr;
+ register JSAMPROW outptr;
+ register JDIMENSION col;
+ register int ci;
+ int nc = cinfo->num_components;
+ JDIMENSION num_cols = cinfo->image_width;
+
+ while (--num_rows >= 0) {
+ /* It seems fastest to make a separate pass for each component. */
+ for (ci = 0; ci < nc; ci++) {
+ inptr = *input_buf;
+ outptr = output_buf[ci][output_row];
+ for (col = 0; col < num_cols; col++) {
+ outptr[col] = inptr[ci]; /* don't need GETJSAMPLE() here */
+ inptr += nc;
+ }
+ }
+ input_buf++;
+ output_row++;
+ }
+}
+
+
+/*
+ * Empty method for start_pass.
+ */
+
+METHODDEF(void)
+null_method (j_compress_ptr cinfo)
+{
+ /* no work needed */
+}
+
+
+/*
+ * Module initialization routine for input colorspace conversion.
+ */
+
+GLOBAL(void)
+jinit_color_converter (j_compress_ptr cinfo)
+{
+ my_cconvert_ptr cconvert;
+
+ cconvert = (my_cconvert_ptr)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ SIZEOF(my_color_converter));
+ cinfo->cconvert = (struct jpeg_color_converter *) cconvert;
+ /* set start_pass to null method until we find out differently */
+ cconvert->pub.start_pass = null_method;
+
+ /* Make sure input_components agrees with in_color_space */
+ switch (cinfo->in_color_space) {
+ case JCS_GRAYSCALE:
+ if (cinfo->input_components != 1)
+ ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+ break;
+
+ case JCS_RGB:
+#if RGB_PIXELSIZE != 3
+ if (cinfo->input_components != RGB_PIXELSIZE)
+ ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+ break;
+#endif /* else share code with YCbCr */
+
+ case JCS_YCbCr:
+ if (cinfo->input_components != 3)
+ ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+ break;
+
+ case JCS_CMYK:
+ case JCS_YCCK:
+ if (cinfo->input_components != 4)
+ ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+ break;
+
+ default: /* JCS_UNKNOWN can be anything */
+ if (cinfo->input_components < 1)
+ ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
+ break;
+ }
+
+ /* Check num_components, set conversion method based on requested space */
+ switch (cinfo->jpeg_color_space) {
+ case JCS_GRAYSCALE:
+ if (cinfo->num_components != 1)
+ ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+ if (cinfo->in_color_space == JCS_GRAYSCALE)
+ cconvert->pub.color_convert = grayscale_convert;
+ else if (cinfo->in_color_space == JCS_RGB) {
+ cconvert->pub.start_pass = rgb_ycc_start;
+ cconvert->pub.color_convert = rgb_gray_convert;
+ } else if (cinfo->in_color_space == JCS_YCbCr)
+ cconvert->pub.color_convert = grayscale_convert;
+ else
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ break;
+
+ case JCS_RGB:
+ if (cinfo->num_components != 3)
+ ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+ if (cinfo->in_color_space == JCS_RGB && RGB_PIXELSIZE == 3)
+ cconvert->pub.color_convert = null_convert;
+ else
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ break;
+
+ case JCS_YCbCr:
+ if (cinfo->num_components != 3)
+ ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+ if (cinfo->in_color_space == JCS_RGB) {
+ cconvert->pub.start_pass = rgb_ycc_start;
+ cconvert->pub.color_convert = rgb_ycc_convert;
+ } else if (cinfo->in_color_space == JCS_YCbCr)
+ cconvert->pub.color_convert = null_convert;
+ else
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ break;
+
+ case JCS_CMYK:
+ if (cinfo->num_components != 4)
+ ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+ if (cinfo->in_color_space == JCS_CMYK)
+ cconvert->pub.color_convert = null_convert;
+ else
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ break;
+
+ case JCS_YCCK:
+ if (cinfo->num_components != 4)
+ ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+ if (cinfo->in_color_space == JCS_CMYK) {
+ cconvert->pub.start_pass = rgb_ycc_start;
+ cconvert->pub.color_convert = cmyk_ycck_convert;
+ } else if (cinfo->in_color_space == JCS_YCCK)
+ cconvert->pub.color_convert = null_convert;
+ else
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ break;
+
+ default: /* allow null conversion of JCS_UNKNOWN */
+ if (cinfo->jpeg_color_space != cinfo->in_color_space ||
+ cinfo->num_components != cinfo->input_components)
+ ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+ cconvert->pub.color_convert = null_convert;
+ break;
+ }
+}
projects / opencv / blobdiff