jccolor.c

MPEG4解码源代码(包含完整的工程文件)

 */

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 long * 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;
  }
}