// 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.
#if !USE_UNSAFE_STUFF
static void ycc_rgb_convert(jpeg_decompress cinfo, byte[][][] input_buf, uint input_row, byte[][] output_buf, uint output_row, int num_rows)
{
my_color_deconverter cconvert = (my_color_deconverter)cinfo.cconvert;
uint num_cols = cinfo.output_width;
int[] Crrtab = cconvert.Cr_r_tab;
int[] Cbbtab = cconvert.Cb_b_tab;
int[] Crgtab = cconvert.Cr_g_tab;
int[] Cbgtab = cconvert.Cb_g_tab;
while (--num_rows >= 0)
{
byte[] inptr0 = input_buf[0][input_row];
byte[] inptr1 = input_buf[1][input_row];
byte[] inptr2 = input_buf[2][input_row];
input_row++;
byte[] outptr = output_buf[output_row++];
for (uint col = 0, outptr_ind = 0; col < num_cols; col++, outptr_ind += RGB_PIXELSIZE)
{
int y = inptr0[col];
int cb = inptr1[col];
int cr = inptr2[col];
// Range-limiting is essential due to noise introduced by DCT losses.
int tmp = y + Crrtab[cr];
outptr[outptr_ind + RGB_RED] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
tmp = y + ((int)((Cbgtab[cb] + Crgtab[cr]) >> SCALEBITS));
outptr[outptr_ind + RGB_GREEN] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
tmp = y + Cbbtab[cb];
outptr[outptr_ind + RGB_BLUE] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
}
}
}
// *************** 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 samples 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.
// Initialize tables for YCC->RGB colorspace conversion.
static void build_ycc_rgb_table(jpeg_decompress cinfo)
{
my_color_deconverter cconvert = (my_color_deconverter)cinfo.cconvert;
try
{
cconvert.Cr_r_tab = new int[MAXJSAMPLE + 1];
cconvert.Cb_b_tab = new int[MAXJSAMPLE + 1];
cconvert.Cr_g_tab = new int[MAXJSAMPLE + 1];
cconvert.Cb_g_tab = new int[MAXJSAMPLE + 1];
}
catch
{
ERREXIT1(cinfo, J_MESSAGE_CODE.JERR_OUT_OF_MEMORY, 4);
}
for (int 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)((FIX_140200 * x + ONE_HALF) >> SCALEBITS);
// Cb=>B value is nearest int to 1.77200 * x
cconvert.Cb_b_tab[i] = (int)((FIX_177200 * x + ONE_HALF) >> SCALEBITS);
// Cr=>G value is scaled-up -0.71414 * x
cconvert.Cr_g_tab[i] = (-FIX_071414) * 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_034414) * x + ONE_HALF;
}
}
// 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.
static void ycck_cmyk_convert(jpeg_decompress cinfo, byte[][][] input_buf, uint input_row, byte[][] output_buf, uint output_row, int num_rows)
{
my_color_deconverter cconvert = (my_color_deconverter)cinfo.cconvert;
uint num_cols = cinfo.output_width;
int[] Crrtab = cconvert.Cr_r_tab;
int[] Cbbtab = cconvert.Cb_b_tab;
int[] Crgtab = cconvert.Cr_g_tab;
int[] Cbgtab = cconvert.Cb_g_tab;
while (--num_rows >= 0)
{
byte[] inptr0 = input_buf[0][input_row];
byte[] inptr1 = input_buf[1][input_row];
byte[] inptr2 = input_buf[2][input_row];
byte[] inptr3 = input_buf[3][input_row];
input_row++;
byte[] outptr = output_buf[output_row++];
int outptr_ind = 0;
for (uint col = 0; col < num_cols; col++)
{
int y = inptr0[col];
int cb = inptr1[col];
int cr = inptr2[col];
// Range-limiting is essential due to noise introduced by DCT losses
int tmp = MAXJSAMPLE - (y + Crrtab[cr]); // red
outptr[outptr_ind++] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
tmp = MAXJSAMPLE - (y + ((int)((Cbgtab[cb] + Crgtab[cr]) >> SCALEBITS))); // green
outptr[outptr_ind++] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
tmp = MAXJSAMPLE - (y + Cbbtab[cb]); // blue
outptr[outptr_ind++] = (byte)(tmp >= MAXJSAMPLE?MAXJSAMPLE:(tmp < 0?0:tmp));
// K passes through unchanged
outptr[outptr_ind++] = inptr3[col];
}
}
}
// Module initialization routine for output colorspace conversion.
public static void jinit_color_deconverter(jpeg_decompress cinfo)
{
my_color_deconverter cconvert = null;
try
{
cconvert = new my_color_deconverter();
}
catch
{
ERREXIT1(cinfo, J_MESSAGE_CODE.JERR_OUT_OF_MEMORY, 4);
}
cinfo.cconvert = cconvert;
cconvert.start_pass = start_pass_dcolor;
// Make sure num_components agrees with jpeg_color_space
switch (cinfo.jpeg_color_space)
{
case J_COLOR_SPACE.JCS_GRAYSCALE: if (cinfo.num_components != 1)
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE);
}
break;
case J_COLOR_SPACE.JCS_RGB:
case J_COLOR_SPACE.JCS_YCbCr: if (cinfo.num_components != 3)
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE);
}
break;
case J_COLOR_SPACE.JCS_CMYK:
case J_COLOR_SPACE.JCS_YCCK: if (cinfo.num_components != 4)
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE);
}
break;
default: if (cinfo.num_components < 1)
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE);
}
break; // JCS_UNKNOWN can be anything
}
// 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 J_COLOR_SPACE.JCS_GRAYSCALE:
cinfo.out_color_components = 1;
if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_GRAYSCALE || cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_YCbCr)
{
cconvert.color_convert = grayscale_convert;
// For color->grayscale conversion, only the Y (0) component is needed
for (int ci = 1; ci < cinfo.num_components; ci++)
{
cinfo.comp_info[ci].component_needed = false;
}
}
else
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL);
}
break;
case J_COLOR_SPACE.JCS_RGB:
cinfo.out_color_components = RGB_PIXELSIZE;
if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_YCbCr)
{
cconvert.color_convert = ycc_rgb_convert;
build_ycc_rgb_table(cinfo);
}
else if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_GRAYSCALE)
{
cconvert.color_convert = gray_rgb_convert;
}
else if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_RGB && RGB_PIXELSIZE == 3)
{
cconvert.color_convert = null_convert;
}
else
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL);
}
break;
case J_COLOR_SPACE.JCS_CMYK:
cinfo.out_color_components = 4;
if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_YCCK)
{
cconvert.color_convert = ycck_cmyk_convert;
build_ycc_rgb_table(cinfo);
}
else if (cinfo.jpeg_color_space == J_COLOR_SPACE.JCS_CMYK)
{
cconvert.color_convert = null_convert;
}
else
{
ERREXIT(cinfo, J_MESSAGE_CODE.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.color_convert = null_convert;
}
else
{
ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL); // unsupported non-null conversion
}
break;
}
if (cinfo.quantize_colors)
{
cinfo.output_components = 1; // single colormapped output component
}
else
{
cinfo.output_components = cinfo.out_color_components;
}
}
// Module initialization routine for output colorspace conversion.
public static void jinit_color_deconverter(jpeg_decompress cinfo)
{
my_color_deconverter cconvert=null;
try
{
cconvert=new my_color_deconverter();
}
catch
{
ERREXIT1(cinfo, J_MESSAGE_CODE.JERR_OUT_OF_MEMORY, 4);
}
cinfo.cconvert=cconvert;
cconvert.start_pass=start_pass_dcolor;
// Make sure num_components agrees with jpeg_color_space
switch(cinfo.jpeg_color_space)
{
case J_COLOR_SPACE.JCS_GRAYSCALE: if(cinfo.num_components!=1) ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE); break;
case J_COLOR_SPACE.JCS_RGB:
case J_COLOR_SPACE.JCS_YCbCr: if(cinfo.num_components!=3) ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE); break;
case J_COLOR_SPACE.JCS_CMYK:
case J_COLOR_SPACE.JCS_YCCK: if(cinfo.num_components!=4) ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE); break;
default: if(cinfo.num_components<1) ERREXIT(cinfo, J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE); break; // JCS_UNKNOWN can be anything
}
// 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 J_COLOR_SPACE.JCS_GRAYSCALE:
cinfo.out_color_components=1;
if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_GRAYSCALE||cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_YCbCr)
{
cconvert.color_convert=grayscale_convert;
// For color->grayscale conversion, only the Y (0) component is needed
for(int ci=1; ci<cinfo.num_components; ci++) cinfo.comp_info[ci].component_needed=false;
}
else ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL);
break;
case J_COLOR_SPACE.JCS_RGB:
cinfo.out_color_components=RGB_PIXELSIZE;
if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_YCbCr)
{
cconvert.color_convert=ycc_rgb_convert;
build_ycc_rgb_table(cinfo);
}
else if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_GRAYSCALE)
{
cconvert.color_convert=gray_rgb_convert;
}
else if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_RGB&&RGB_PIXELSIZE==3) cconvert.color_convert=null_convert;
else ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL);
break;
case J_COLOR_SPACE.JCS_CMYK:
cinfo.out_color_components=4;
if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_YCCK)
{
cconvert.color_convert=ycck_cmyk_convert;
build_ycc_rgb_table(cinfo);
}
else if(cinfo.jpeg_color_space==J_COLOR_SPACE.JCS_CMYK) cconvert.color_convert=null_convert;
else ERREXIT(cinfo, J_MESSAGE_CODE.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.color_convert=null_convert;
}
else ERREXIT(cinfo, J_MESSAGE_CODE.JERR_CONVERSION_NOTIMPL); // unsupported non-null conversion
break;
}
if(cinfo.quantize_colors) cinfo.output_components=1; // single colormapped output component
else cinfo.output_components=cinfo.out_color_components;
}
