/* * jdcolor.c * * Copyright (C) 1991-1997, 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 output colorspace conversion routines. */#define JPEG_INTERNALS#include "jinclude.h"#include "jpeglib.h"/* Private subobject */typedef struct {  struct jpeg_color_deconverter pub; /* public fields */  /* Private state for 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 */} my_color_deconverter;typedef my_color_deconverter * my_cconvert_ptr;/**************** YCbCr -> RGB 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 *	R = Y                + 1.40200 * Cr *	G = Y - 0.34414 * Cb - 0.71414 * Cr *	B = Y + 1.77200 * Cb * where Cb and Cr represent the incoming values less CENTERJSAMPLE. * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.) * * 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 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 YCC->RGB colorspace conversion. */LOCAL(void)build_ycc_rgb_table (j_decompress_ptr cinfo){  // we comment it for hardware simulation  /*  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 1.40200 * 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     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     // 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;  }  */}/* * 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. */      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 YCbCr -> RGB **************//* * Color conversion for no colorspace change: just copy the data, * converting from separate-planes to interleaved representation. */METHODDEF(void)null_convert (j_decompress_ptr cinfo,	      JSAMPIMAGE input_buf, JDIMENSION input_row,	      JSAMPARRAY output_buf, int num_rows){  register JSAMPROW inptr, outptr;  register JDIMENSION count;  register int num_components = cinfo->num_components;  JDIMENSION num_cols = cinfo->output_width;  int ci;  while (--num_rows >= 0) {    for (ci = 0; ci < num_components; ci++) {      inptr = input_buf[ci][input_row];      outptr = output_buf[0] + ci;      for (count = num_cols; count > 0; count--) {	*outptr = *inptr++;	/* needn't bother with GETJSAMPLE() here */	outptr += num_components;      }    }    input_row++;    output_buf++;  }}/* * Color conversion for grayscale: just copy the data. * This also works for YCbCr -> 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], (int) input_row, output_buf, 0,		    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 inptr, outptr;  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;    }  }}/* * Adobe-style YCCK->CMYK conversion. * 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. */      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;    }  }}/* * 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;  cconvert = (my_cconvert_ptr)    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,				SIZEOF(my_color_deconverter));  cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert;  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:    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);    break;  }  /* Set out_color_components and conversion method based on requested space.   * Also clear 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;    if (cinfo->jpeg_color_space == JCS_GRAYSCALE ||	cinfo->jpeg_color_space == JCS_YCbCr) {      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      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);    break;  case JCS_RGB:    cinfo->out_color_components = RGB_PIXELSIZE;    if (cinfo->jpeg_color_space == 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 && RGB_PIXELSIZE == 3) {      cconvert->pub.color_convert = null_convert;    } else      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);    break;  case JCS_CMYK:    cinfo->out_color_components = 4;    if (cinfo->jpeg_color_space == JCS_YCCK) {      cconvert->pub.color_convert = ycck_cmyk_convert;      build_ycc_rgb_table(cinfo);    } else if (cinfo->jpeg_color_space == JCS_CMYK) {      cconvert->pub.color_convert = null_convert;    } else      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);    break;  default:    /* Permit null conversion to same output space */    if (cinfo->out_color_space == cinfo->jpeg_color_space) {      cinfo->out_color_components = cinfo->num_components;      cconvert->pub.color_convert = null_convert;    } else			/* unsupported non-null conversion */      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);    break;  }  if (cinfo->quantize_colors)    cinfo->output_components = 1; /* single colormapped output component */  else    cinfo->output_components = cinfo->out_color_components;}