CMYK/YCCK support

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@680 632fc199-4ca6-4c93-a231-07263d6284db

ChangeLog.txt

@@ -61,6 +61,8 @@ worst-case JPEG size based on the level of chrominance subsampling.
 [16] Fixed 32-bit supplementary package for amd64 Debian systems which was
 broken by enhancements to the packaging system in 1.1.
 
+[17] Support for decoding JPEG images that use the YMCK or YCCK colorspaces.
+
 
 1.1.1
 =====

jdcolor.c

@@ -107,6 +107,103 @@ build_ycc_rgb_table (j_decompress_ptr cinfo)
   }
 }
 
+/*
+ * Convert inverted CMYK to RGB
+ */
+METHODDEF(void)
+cmyk_rgb_convert (j_decompress_ptr cinfo,
+                  JSAMPIMAGE input_buf, JDIMENSION input_row,
+                  JSAMPARRAY output_buf, int num_rows)
+{
+  double cyan, magenta, yellow, black;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+  int rindex = rgb_red[cinfo->out_color_space];
+  int gindex = rgb_green[cinfo->out_color_space];
+  int bindex = rgb_blue[cinfo->out_color_space];
+  int rgbstride = rgb_pixelsize[cinfo->out_color_space];
+
+  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++) {
+      cyan    = (double) GETJSAMPLE(inptr0[col]);
+      magenta = (double) GETJSAMPLE(inptr1[col]);
+      yellow  = (double) GETJSAMPLE(inptr2[col]);
+      black   = (double) GETJSAMPLE(inptr3[col]);
+
+      outptr[rindex] = (JSAMPLE)(cyan * black / (double)MAXJSAMPLE);
+      outptr[gindex] = (JSAMPLE)(magenta * black / (double)MAXJSAMPLE);
+      outptr[bindex] = (JSAMPLE)(yellow * black / (double)MAXJSAMPLE);
+      outptr += rgbstride;
+    }
+  }
+}
+
+/*
+ * Convert YCCK to RGB
+ */
+METHODDEF(void)
+ycck_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;
+  double cyan, magenta, yellow, black;
+  register int y, cb, cr;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+  int rindex = rgb_red[cinfo->out_color_space];
+  int gindex = rgb_green[cinfo->out_color_space];
+  int bindex = rgb_blue[cinfo->out_color_space];
+  int rgbstride = rgb_pixelsize[cinfo->out_color_space];
+
+  /* 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++) {
+
+      /********* Read YCCK Pixel **********/ 
+      y     = GETJSAMPLE(inptr0[col]);
+      cb    = GETJSAMPLE(inptr1[col]);
+      cr    = GETJSAMPLE(inptr2[col]);
+      black = (double)GETJSAMPLE(inptr3[col]);
+
+      /********* Convert  YCCK to CMYK  **********/ 
+      /* Range-limiting is essential due to noise introduced by DCT losses. */
+      cyan    = (double)range_limit[MAXJSAMPLE - (y + Crrtab[cr])];
+      magenta = (double)range_limit[MAXJSAMPLE -
+        (y + ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS)))];
+      yellow  = (double)range_limit[MAXJSAMPLE - (y + Cbbtab[cb])];
+
+      /********* Convert  CMYK to RGB  **********/ 
+      outptr[rindex] = (JSAMPLE)(cyan * black / (double)MAXJSAMPLE);
+      outptr[gindex] = (JSAMPLE)(magenta * black / (double)MAXJSAMPLE);
+      outptr[bindex] = (JSAMPLE)(yellow * black / (double)MAXJSAMPLE);
+      outptr += rgbstride;
+    }
+  }
+}
 
 /*
  * Convert some rows of samples to the output colorspace.
@@ -386,6 +483,11 @@ jinit_color_deconverter (j_decompress_ptr cinfo)
     } else if (cinfo->jpeg_color_space == cinfo->out_color_space &&
       rgb_pixelsize[cinfo->out_color_space] == 3) {
       cconvert->pub.color_convert = null_convert;
+    } else if (cinfo->jpeg_color_space == JCS_CMYK) {
+      cconvert->pub.color_convert = cmyk_rgb_convert;
+    } else if (cinfo->jpeg_color_space == JCS_YCCK) {
+      cconvert->pub.color_convert = ycck_rgb_convert;
+      build_ycc_rgb_table(cinfo);
     } else
       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
     break;