jdcolor.cpp File Reference

#include "jinclude.h"
#include "jpeglib.h"

Include dependency graph for jdcolor.cpp:

Classes
struct	my_color_deconverter

Macros
#define	JPEG_INTERNALS
#define	SCALEBITS   16 /* speediest right-shift on some machines */
#define	ONE_HALF   ((int32_t) 1 << (SCALEBITS-1))
#define	FIX(x)   ((int32_t) ((x) * (1L<<SCALEBITS) + 0.5))

Typedefs
typedef my_color_deconverter *	my_cconvert_ptr

Functions
static void	build_ycc_rgb_table (j_decompress_ptr cinfo)
static void	ycc_rgb_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
static void	null_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
static void	grayscale_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
static void	gray_rgb_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
static void	ycck_cmyk_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
static void	start_pass_dcolor (j_decompress_ptr cinfo)
void	jinit_color_deconverter (j_decompress_ptr cinfo)

Macro Definition Documentation

#define JPEG_INTERNALS

#define SCALEBITS   16 /* speediest right-shift on some machines */

#define ONE_HALF   ((int32_t) 1 << (SCALEBITS-1))

#define FIX

(

x

)

((int32_t) ((x) * (1L<<SCALEBITS) + 0.5))

Typedef Documentation

typedef my_color_deconverter* my_cconvert_ptr

Function Documentation

static void build_ycc_rgb_table ( j_decompress_ptr  cinfo )

static

{
  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
  int i;
  int32_t 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_t *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                (MAXJSAMPLE+1) * SIZEOF(int32_t));
  cconvert->Cb_g_tab = (int32_t *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                (MAXJSAMPLE+1) * SIZEOF(int32_t));

  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;
  }
}

static void ycc_rgb_convert ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION  input_row, JSAMPARRAY  output_buf, int  num_rows  )

static

{
  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_t * Crgtab = cconvert->Cr_g_tab;
  register int32_t * 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;
    }
  }
}

static void null_convert ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION  input_row, JSAMPARRAY  output_buf, int  num_rows  )

static

{
  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++;
  }
}

static void grayscale_convert ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION  input_row, JSAMPARRAY  output_buf, int  num_rows  )

static

{
  jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0,
            num_rows, cinfo->output_width);
}

static void gray_rgb_convert ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION  input_row, JSAMPARRAY  output_buf, int  num_rows  )

static

{
  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;
    }
  }
}

static void ycck_cmyk_convert ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION  input_row, JSAMPARRAY  output_buf, int  num_rows  )

static

{
  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_t * Crgtab = cconvert->Cr_g_tab;
  register int32_t * 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;
    }
  }
}

static void start_pass_dcolor ( j_decompress_ptr  cinfo )

static

{
  /* no work needed */
}

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;
}