src/jpeg/jdcolor.c

/*
 * 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"

#if defined(__VISAGECPP__)
/* Visual Age fixups for multiple declarations */
#  define null_convert   null_convert2 /* already in jcmaint.c */
#  define grayscale_convert   grayscale_convert2 /* already in jcmaint.c */
#endif

/* 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 */
  JPEG_INT32 * Cr_g_tab;		/* => table for Cr to G conversion */
  JPEG_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	((JPEG_INT32) 1 << (SCALEBITS-1))
#define FIX(x)		((JPEG_INT32) ((x) * (1L<<SCALEBITS) + 0.5))


/*
 * Initialize tables for YCC->RGB colorspace conversion.
 */

LOCAL(void)
build_ycc_rgb_table (j_decompress_ptr cinfo)
{
  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
  int i;
  JPEG_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 = (JPEG_INT32 *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
  cconvert->Cb_g_tab = (JPEG_INT32 *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				(MAXJSAMPLE+1) * SIZEOF(JPEG_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 JPEG_INT32 * Crgtab = cconvert->Cr_g_tab;
  register JPEG_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 JPEG_INT32 * Crgtab = cconvert->Cr_g_tab;
  register JPEG_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;
}

#if defined(__VISAGECPP__)
#  ifdef null_convert2
#   undef null_convert2
#  endif
#  ifdef grayscale_convert2
#   undef grayscale_convert2
#  endif
#endif
Commit	Line	Data
	1	/*
	2	* jdcolor.c
	3	*
	4	* Copyright (C) 1991-1997, Thomas G. Lane.
	5	* This file is part of the Independent JPEG Group's software.
	6	* For conditions of distribution and use, see the accompanying README file.
	7	*
	8	* This file contains output colorspace conversion routines.
	9	*/
	10
	11	#define JPEG_INTERNALS
	12	#include "jinclude.h"
	13	#include "jpeglib.h"
	14
	15	#if defined(__VISAGECPP__)
	16	/* Visual Age fixups for multiple declarations */
	17	# define null_convert null_convert2 /* already in jcmaint.c */
	18	# define grayscale_convert grayscale_convert2 /* already in jcmaint.c */
	19	#endif
	20
	21	/* Private subobject */
	22
	23	typedef struct {
	24	struct jpeg_color_deconverter pub; /* public fields */
	25
	26	/* Private state for YCC->RGB conversion */
	27	int * Cr_r_tab; /* => table for Cr to R conversion */
	28	int * Cb_b_tab; /* => table for Cb to B conversion */
	29	JPEG_INT32 * Cr_g_tab; /* => table for Cr to G conversion */
	30	JPEG_INT32 * Cb_g_tab; /* => table for Cb to G conversion */
	31	} my_color_deconverter;
	32
	33	typedef my_color_deconverter * my_cconvert_ptr;
	34
	35
	36	/************** YCbCr -> RGB conversion: most common case ************/
	37
	38	/*
	39	* YCbCr is defined per CCIR 601-1, except that Cb and Cr are
	40	* normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
	41	* The conversion equations to be implemented are therefore
	42	* R = Y + 1.40200 * Cr
	43	* G = Y - 0.34414 * Cb - 0.71414 * Cr
	44	* B = Y + 1.77200 * Cb
	45	* where Cb and Cr represent the incoming values less CENTERJSAMPLE.
	46	* (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
	47	*
	48	* To avoid floating-point arithmetic, we represent the fractional constants
	49	* as integers scaled up by 2^16 (about 4 digits precision); we have to divide
	50	* the products by 2^16, with appropriate rounding, to get the correct answer.
	51	* Notice that Y, being an integral input, does not contribute any fraction
	52	* so it need not participate in the rounding.
	53	*
	54	* For even more speed, we avoid doing any multiplications in the inner loop
	55	* by precalculating the constants times Cb and Cr for all possible values.
	56	* For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
	57	* for 12-bit samples it is still acceptable. It's not very reasonable for
	58	* 16-bit samples, but if you want lossless storage you shouldn't be changing
	59	* colorspace anyway.
	60	* The Cr=>R and Cb=>B values can be rounded to integers in advance; the
	61	* values for the G calculation are left scaled up, since we must add them
	62	* together before rounding.
	63	*/
	64
	65	#define SCALEBITS 16 /* speediest right-shift on some machines */
	66	#define ONE_HALF ((JPEG_INT32) 1 << (SCALEBITS-1))
	67	#define FIX(x) ((JPEG_INT32) ((x) * (1L<<SCALEBITS) + 0.5))
	68
	69
	70	/*
	71	* Initialize tables for YCC->RGB colorspace conversion.
	72	*/
	73
	74	LOCAL(void)
	75	build_ycc_rgb_table (j_decompress_ptr cinfo)
	76	{
	77	my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
	78	int i;
	79	JPEG_INT32 x;
	80	SHIFT_TEMPS
	81
	82	cconvert->Cr_r_tab = (int *)
	83	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	84	(MAXJSAMPLE+1) * SIZEOF(int));
	85	cconvert->Cb_b_tab = (int *)
	86	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	87	(MAXJSAMPLE+1) * SIZEOF(int));
	88	cconvert->Cr_g_tab = (JPEG_INT32 *)
	89	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	90	(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
	91	cconvert->Cb_g_tab = (JPEG_INT32 *)
	92	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	93	(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
	94
	95	for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
	96	/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
	97	/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
	98	/* Cr=>R value is nearest int to 1.40200 * x */
	99	cconvert->Cr_r_tab[i] = (int)
	100	RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
	101	/* Cb=>B value is nearest int to 1.77200 * x */
	102	cconvert->Cb_b_tab[i] = (int)
	103	RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
	104	/* Cr=>G value is scaled-up -0.71414 * x */
	105	cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x;
	106	/* Cb=>G value is scaled-up -0.34414 * x */
	107	/* We also add in ONE_HALF so that need not do it in inner loop */
	108	cconvert->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
	109	}
	110	}
	111
	112
	113	/*
	114	* Convert some rows of samples to the output colorspace.
	115	*
	116	* Note that we change from noninterleaved, one-plane-per-component format
	117	* to interleaved-pixel format. The output buffer is therefore three times
	118	* as wide as the input buffer.
	119	* A starting row offset is provided only for the input buffer. The caller
	120	* can easily adjust the passed output_buf value to accommodate any row
	121	* offset required on that side.
	122	*/
	123
	124	METHODDEF(void)
	125	ycc_rgb_convert (j_decompress_ptr cinfo,
	126	JSAMPIMAGE input_buf, JDIMENSION input_row,
	127	JSAMPARRAY output_buf, int num_rows)
	128	{
	129	my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
	130	register int y, cb, cr;
	131	register JSAMPROW outptr;
	132	register JSAMPROW inptr0, inptr1, inptr2;
	133	register JDIMENSION col;
	134	JDIMENSION num_cols = cinfo->output_width;
	135	/* copy these pointers into registers if possible */
	136	register JSAMPLE * range_limit = cinfo->sample_range_limit;
	137	register int * Crrtab = cconvert->Cr_r_tab;
	138	register int * Cbbtab = cconvert->Cb_b_tab;
	139	register JPEG_INT32 * Crgtab = cconvert->Cr_g_tab;
	140	register JPEG_INT32 * Cbgtab = cconvert->Cb_g_tab;
	141	SHIFT_TEMPS
	142
	143	while (--num_rows >= 0) {
	144	inptr0 = input_buf[0][input_row];
	145	inptr1 = input_buf[1][input_row];
	146	inptr2 = input_buf[2][input_row];
	147	input_row++;
	148	outptr = *output_buf++;
	149	for (col = 0; col < num_cols; col++) {
	150	y = GETJSAMPLE(inptr0[col]);
	151	cb = GETJSAMPLE(inptr1[col]);
	152	cr = GETJSAMPLE(inptr2[col]);
	153	/* Range-limiting is essential due to noise introduced by DCT losses. */
	154	outptr[RGB_RED] = range_limit[y + Crrtab[cr]];
	155	outptr[RGB_GREEN] = range_limit[y +
	156	((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
	157	SCALEBITS))];
	158	outptr[RGB_BLUE] = range_limit[y + Cbbtab[cb]];
	159	outptr += RGB_PIXELSIZE;
	160	}
	161	}
	162	}
	163
	164
	165	/************** Cases other than YCbCr -> RGB ************/
	166
	167
	168	/*
	169	* Color conversion for no colorspace change: just copy the data,
	170	* converting from separate-planes to interleaved representation.
	171	*/
	172
	173	METHODDEF(void)
	174	null_convert (j_decompress_ptr cinfo,
	175	JSAMPIMAGE input_buf, JDIMENSION input_row,
	176	JSAMPARRAY output_buf, int num_rows)
	177	{
	178	register JSAMPROW inptr, outptr;
	179	register JDIMENSION count;
	180	register int num_components = cinfo->num_components;
	181	JDIMENSION num_cols = cinfo->output_width;
	182	int ci;
	183
	184	while (--num_rows >= 0) {
	185	for (ci = 0; ci < num_components; ci++) {
	186	inptr = input_buf[ci][input_row];
	187	outptr = output_buf[0] + ci;
	188	for (count = num_cols; count > 0; count--) {
	189	outptr = inptr++; /* needn't bother with GETJSAMPLE() here */
	190	outptr += num_components;
	191	}
	192	}
	193	input_row++;
	194	output_buf++;
	195	}
	196	}
	197
	198
	199	/*
	200	* Color conversion for grayscale: just copy the data.
	201	* This also works for YCbCr -> grayscale conversion, in which
	202	* we just copy the Y (luminance) component and ignore chrominance.
	203	*/
	204
	205	METHODDEF(void)
	206	grayscale_convert (j_decompress_ptr cinfo,
	207	JSAMPIMAGE input_buf, JDIMENSION input_row,
	208	JSAMPARRAY output_buf, int num_rows)
	209	{
	210	jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0,
	211	num_rows, cinfo->output_width);
	212	}
	213
	214
	215	/*
	216	* Convert grayscale to RGB: just duplicate the graylevel three times.
	217	* This is provided to support applications that don't want to cope
	218	* with grayscale as a separate case.
	219	*/
	220
	221	METHODDEF(void)
	222	gray_rgb_convert (j_decompress_ptr cinfo,
	223	JSAMPIMAGE input_buf, JDIMENSION input_row,
	224	JSAMPARRAY output_buf, int num_rows)
	225	{
	226	register JSAMPROW inptr, outptr;
	227	register JDIMENSION col;
	228	JDIMENSION num_cols = cinfo->output_width;
	229
	230	while (--num_rows >= 0) {
	231	inptr = input_buf[0][input_row++];
	232	outptr = *output_buf++;
	233	for (col = 0; col < num_cols; col++) {
	234	/* We can dispense with GETJSAMPLE() here */
	235	outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
	236	outptr += RGB_PIXELSIZE;
	237	}
	238	}
	239	}
	240
	241
	242	/*
	243	* Adobe-style YCCK->CMYK conversion.
	244	* We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same
	245	* conversion as above, while passing K (black) unchanged.
	246	* We assume build_ycc_rgb_table has been called.
	247	*/
	248
	249	METHODDEF(void)
	250	ycck_cmyk_convert (j_decompress_ptr cinfo,
	251	JSAMPIMAGE input_buf, JDIMENSION input_row,
	252	JSAMPARRAY output_buf, int num_rows)
	253	{
	254	my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
	255	register int y, cb, cr;
	256	register JSAMPROW outptr;
	257	register JSAMPROW inptr0, inptr1, inptr2, inptr3;
	258	register JDIMENSION col;
	259	JDIMENSION num_cols = cinfo->output_width;
	260	/* copy these pointers into registers if possible */
	261	register JSAMPLE * range_limit = cinfo->sample_range_limit;
	262	register int * Crrtab = cconvert->Cr_r_tab;
	263	register int * Cbbtab = cconvert->Cb_b_tab;
	264	register JPEG_INT32 * Crgtab = cconvert->Cr_g_tab;
	265	register JPEG_INT32 * Cbgtab = cconvert->Cb_g_tab;
	266	SHIFT_TEMPS
	267
	268	while (--num_rows >= 0) {
	269	inptr0 = input_buf[0][input_row];
	270	inptr1 = input_buf[1][input_row];
	271	inptr2 = input_buf[2][input_row];
	272	inptr3 = input_buf[3][input_row];
	273	input_row++;
	274	outptr = *output_buf++;
	275	for (col = 0; col < num_cols; col++) {
	276	y = GETJSAMPLE(inptr0[col]);
	277	cb = GETJSAMPLE(inptr1[col]);
	278	cr = GETJSAMPLE(inptr2[col]);
	279	/* Range-limiting is essential due to noise introduced by DCT losses. */
	280	outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])]; /* red */
	281	outptr[1] = range_limit[MAXJSAMPLE - (y + /* green */
	282	((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
	283	SCALEBITS)))];
	284	outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])]; /* blue */
	285	/* K passes through unchanged */
	286	outptr[3] = inptr3[col]; /* don't need GETJSAMPLE here */
	287	outptr += 4;
	288	}
	289	}
	290	}
	291
	292
	293	/*
	294	* Empty method for start_pass.
	295	*/
	296
	297	METHODDEF(void)
	298	start_pass_dcolor (j_decompress_ptr cinfo)
	299	{
	300	/* no work needed */
	301	}
	302
	303
	304	/*
	305	* Module initialization routine for output colorspace conversion.
	306	*/
	307
	308	GLOBAL(void)
	309	jinit_color_deconverter (j_decompress_ptr cinfo)
	310	{
	311	my_cconvert_ptr cconvert;
	312	int ci;
	313
	314	cconvert = (my_cconvert_ptr)
	315	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	316	SIZEOF(my_color_deconverter));
	317	cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert;
	318	cconvert->pub.start_pass = start_pass_dcolor;
	319
	320	/* Make sure num_components agrees with jpeg_color_space */
	321	switch (cinfo->jpeg_color_space) {
	322	case JCS_GRAYSCALE:
	323	if (cinfo->num_components != 1)
	324	ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
	325	break;
	326
	327	case JCS_RGB:
	328	case JCS_YCbCr:
	329	if (cinfo->num_components != 3)
	330	ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
	331	break;
	332
	333	case JCS_CMYK:
	334	case JCS_YCCK:
	335	if (cinfo->num_components != 4)
	336	ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
	337	break;
	338
	339	default: /* JCS_UNKNOWN can be anything */
	340	if (cinfo->num_components < 1)
	341	ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
	342	break;
	343	}
	344
	345	/* Set out_color_components and conversion method based on requested space.
	346	* Also clear the component_needed flags for any unused components,
	347	* so that earlier pipeline stages can avoid useless computation.
	348	*/
	349
	350	switch (cinfo->out_color_space) {
	351	case JCS_GRAYSCALE:
	352	cinfo->out_color_components = 1;
	353	if (cinfo->jpeg_color_space == JCS_GRAYSCALE \|\|
	354	cinfo->jpeg_color_space == JCS_YCbCr) {
	355	cconvert->pub.color_convert = grayscale_convert;
	356	/* For color->grayscale conversion, only the Y (0) component is needed */
	357	for (ci = 1; ci < cinfo->num_components; ci++)
	358	cinfo->comp_info[ci].component_needed = FALSE;
	359	} else
	360	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
	361	break;
	362
	363	case JCS_RGB:
	364	cinfo->out_color_components = RGB_PIXELSIZE;
	365	if (cinfo->jpeg_color_space == JCS_YCbCr) {
	366	cconvert->pub.color_convert = ycc_rgb_convert;
	367	build_ycc_rgb_table(cinfo);
	368	} else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) {
	369	cconvert->pub.color_convert = gray_rgb_convert;
	370	} else if (cinfo->jpeg_color_space == JCS_RGB && RGB_PIXELSIZE == 3) {
	371	cconvert->pub.color_convert = null_convert;
	372	} else
	373	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
	374	break;
	375
	376	case JCS_CMYK:
	377	cinfo->out_color_components = 4;
	378	if (cinfo->jpeg_color_space == JCS_YCCK) {
	379	cconvert->pub.color_convert = ycck_cmyk_convert;
	380	build_ycc_rgb_table(cinfo);
	381	} else if (cinfo->jpeg_color_space == JCS_CMYK) {
	382	cconvert->pub.color_convert = null_convert;
	383	} else
	384	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
	385	break;
	386
	387	default:
	388	/* Permit null conversion to same output space */
	389	if (cinfo->out_color_space == cinfo->jpeg_color_space) {
	390	cinfo->out_color_components = cinfo->num_components;
	391	cconvert->pub.color_convert = null_convert;
	392	} else /* unsupported non-null conversion */
	393	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
	394	break;
	395	}
	396
	397	if (cinfo->quantize_colors)
	398	cinfo->output_components = 1; /* single colormapped output component */
	399	else
	400	cinfo->output_components = cinfo->out_color_components;
	401	}
	402
	403	#if defined(__VISAGECPP__)
	404	# ifdef null_convert2
	405	# undef null_convert2
	406	# endif
	407	# ifdef grayscale_convert2
	408	# undef grayscale_convert2
	409	# endif
	410	#endif