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Diffstat (limited to 'src/libjpeg/jccolor.c')
| -rw-r--r-- | src/libjpeg/jccolor.c | 459 |
1 files changed, 459 insertions, 0 deletions
diff --git a/src/libjpeg/jccolor.c b/src/libjpeg/jccolor.c new file mode 100644 index 0000000..0a8a4b5 --- /dev/null +++ b/src/libjpeg/jccolor.c @@ -0,0 +1,459 @@ +/* + * 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; + } +} |