| /* |
| * 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; |
| } |
| } |