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modules/javafx.graphics/src/main/native-iio/libjpeg7/jdcolor.c

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@@ -1,9 +1,10 @@
 /*
  * jdcolor.c
  *
  * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Modified 2011-2017 by Guido Vollbeding.
  * 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.
  */

@@ -11,65 +12,154 @@
 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"
 
 
+#if RANGE_BITS < 2
+  /* Deliberate syntax err */
+  Sorry, this code requires 2 or more range extension bits.
+#endif
+
+
 /* Private subobject */
 
 typedef struct {
   struct jpeg_color_deconverter pub; /* public fields */
 
-  /* Private state for YCC->RGB conversion */
+  /* Private state for YCbCr->RGB and BG_YCC->RGB conversion */
   int * Cr_r_tab;               /* => table for Cr to R conversion */
   int * Cb_b_tab;               /* => table for Cb to B conversion */
   INT32 * Cr_g_tab;             /* => table for Cr to G conversion */
   INT32 * Cb_g_tab;             /* => table for Cb to G conversion */
+
+  /* Private state for RGB->Y conversion */
+  INT32 * rgb_y_tab;            /* => table for RGB to Y conversion */
 } my_color_deconverter;
 
 typedef my_color_deconverter * my_cconvert_ptr;
 
 
-/**************** YCbCr -> RGB conversion: most common case **************/
+/***************  YCbCr -> RGB conversion: most common case **************/
+/*************** BG_YCC -> RGB conversion: less common case **************/
+/***************    RGB -> Y   conversion: less 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
+ * YCbCr is defined per Recommendation ITU-R BT.601-7 (03/2011),
+ * previously known as Recommendation CCIR 601-1, except that Cb and Cr
+ * are normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
+ * sRGB (standard RGB color space) is defined per IEC 61966-2-1:1999.
+ * sYCC (standard luma-chroma-chroma color space with extended gamut)
+ * is defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex F.
+ * bg-sRGB and bg-sYCC (big gamut standard color spaces)
+ * are defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex G.
+ * Note that the derived conversion coefficients given in some of these
+ * documents are imprecise.  The general conversion equations are
+ *
+ *      R = Y + K * (1 - Kr) * Cr
+ *      G = Y - K * (Kb * (1 - Kb) * Cb + Kr * (1 - Kr) * Cr) / (1 - Kr - Kb)
+ *      B = Y + K * (1 - Kb) * Cb
+ *
+ *      Y = Kr * R + (1 - Kr - Kb) * G + Kb * B
+ *
+ * With Kr = 0.299 and Kb = 0.114 (derived according to SMPTE RP 177-1993
+ * from the 1953 FCC NTSC primaries and CIE Illuminant C), K = 2 for sYCC,
+ * the conversion equations to be implemented are therefore
+ *
+ *      R = Y + 1.402 * Cr
+ *      G = Y - 0.344136286 * Cb - 0.714136286 * Cr
+ *      B = Y + 1.772 * Cb
+ *
+ *      Y = 0.299 * R + 0.587 * G + 0.114 * B
+ *
  * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
- * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
+ * For bg-sYCC, with K = 4, the equations are
+ *
+ *      R = Y + 2.804 * Cr
+ *      G = Y - 0.688272572 * Cb - 1.428272572 * Cr
+ *      B = Y + 3.544 * Cb
  *
  * 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.
+ * for 9-bit to 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        ((INT32) 1 << (SCALEBITS-1))
 #define FIX(x)          ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
 
+/* We allocate one big table for RGB->Y conversion and divide it up into
+ * three parts, instead of doing three alloc_small requests.  This lets us
+ * use a single table base address, which can be held in a register in the
+ * inner loops on many machines (more than can hold all three addresses,
+ * anyway).
+ */
+
+#define R_Y_OFF         0                       /* offset to R => Y section */
+#define G_Y_OFF         (1*(MAXJSAMPLE+1))      /* offset to G => Y section */
+#define B_Y_OFF         (2*(MAXJSAMPLE+1))      /* etc. */
+#define TABLE_SIZE      (3*(MAXJSAMPLE+1))
+
 
 /*
- * Initialize tables for YCC->RGB colorspace conversion.
+ * Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
  */
 
 LOCAL(void)
 build_ycc_rgb_table (j_decompress_ptr cinfo)
+/* Normal case, sYCC */
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  int i;
+  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 = (INT32 *)
+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+                                (MAXJSAMPLE+1) * SIZEOF(INT32));
+  cconvert->Cb_g_tab = (INT32 *)
+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+                                (MAXJSAMPLE+1) * SIZEOF(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 1.402 * x */
+    cconvert->Cr_r_tab[i] = (int)
+                    RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS);
+    /* Cb=>B value is nearest int to 1.772 * x */
+    cconvert->Cb_b_tab[i] = (int)
+                    RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, SCALEBITS);
+    /* Cr=>G value is scaled-up -0.714136286 * x */
+    cconvert->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
+    /* Cb=>G value is scaled-up -0.344136286 * x */
+    /* We also add in ONE_HALF so that need not do it in inner loop */
+    cconvert->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
+  }
+}
+
+
+LOCAL(void)
+build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
+/* Wide gamut case, bg-sYCC */
 {
   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
   int i;
   INT32 x;
   SHIFT_TEMPS

@@ -88,21 +178,21 @@
                                 (MAXJSAMPLE+1) * SIZEOF(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 */
+    /* Cr=>R value is nearest int to 2.804 * 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 */
+                    RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS);
+    /* Cb=>B value is nearest int to 3.544 * 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 */
+                    RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, SCALEBITS);
+    /* Cr=>G value is scaled-up -1.428272572 * x */
+    cconvert->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
+    /* Cb=>G value is scaled-up -0.688272572 * 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;
+    cconvert->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
   }
 }
 
 
 /*

@@ -143,11 +233,13 @@
     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. */
+      /* Range-limiting is essential due to noise introduced by DCT losses,
+       * for extended gamut (sYCC) and wide gamut (bg-sYCC) encodings.
+       */
       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]];

@@ -155,197 +247,264 @@
     }
   }
 }
 
 
-/**************** Cases other than YCbCr -> RGB **************/
+/**************** Cases other than YCC -> RGB ****************/
 
 
 /*
- * Color conversion for no colorspace change: just copy the data,
- * converting from separate-planes to interleaved representation.
+ * Initialize for RGB->grayscale colorspace conversion.
  */
 
-METHODDEF(void)
-null_convert (j_decompress_ptr cinfo,
-              JSAMPIMAGE input_buf, JDIMENSION input_row,
-              JSAMPARRAY output_buf, int num_rows)
+LOCAL(void)
+build_rgb_y_table (j_decompress_ptr cinfo)
 {
-  register JSAMPROW inptr, outptr;
-  register JDIMENSION count;
-  register int num_components = cinfo->num_components;
-  JDIMENSION num_cols = cinfo->output_width;
-  int ci;
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  INT32 * rgb_y_tab;
+  INT32 i;
 
-  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++;
+  /* Allocate and fill in the conversion tables. */
+  cconvert->rgb_y_tab = rgb_y_tab = (INT32 *)
+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+                                (TABLE_SIZE * SIZEOF(INT32)));
+
+  for (i = 0; i <= MAXJSAMPLE; i++) {
+    rgb_y_tab[i+R_Y_OFF] = FIX(0.299) * i;
+    rgb_y_tab[i+G_Y_OFF] = FIX(0.587) * i;
+    rgb_y_tab[i+B_Y_OFF] = FIX(0.114) * i + ONE_HALF;
   }
 }
 
 
 /*
- * 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.
+ * Convert RGB to grayscale.
  */
 
 METHODDEF(void)
-grayscale_convert (j_decompress_ptr cinfo,
+rgb_gray_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);
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register INT32 * ctab = cconvert->rgb_y_tab;
+  register int r, g, b;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  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++) {
+      r = GETJSAMPLE(inptr0[col]);
+      g = GETJSAMPLE(inptr1[col]);
+      b = GETJSAMPLE(inptr2[col]);
+      /* Y */
+      outptr[col] = (JSAMPLE)
+                ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+                 >> SCALEBITS);
+    }
+  }
 }
 
 
 /*
- * 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.
+ * [R-G,G,B-G] to [R,G,B] conversion with modulo calculation
+ * (inverse color transform).
+ * This can be seen as an adaption of the general YCbCr->RGB
+ * conversion equation with Kr = Kb = 0, while replacing the
+ * normalization by modulo calculation.
  */
 
 METHODDEF(void)
-gray_rgb_convert (j_decompress_ptr cinfo,
+rgb1_rgb_convert (j_decompress_ptr cinfo,
                   JSAMPIMAGE input_buf, JDIMENSION input_row,
                   JSAMPARRAY output_buf, int num_rows)
 {
-  register JSAMPROW inptr, outptr;
+  register int r, g, b;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
   register JDIMENSION col;
   JDIMENSION num_cols = cinfo->output_width;
 
   while (--num_rows >= 0) {
-    inptr = input_buf[0][input_row++];
+    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++) {
-      /* We can dispense with GETJSAMPLE() here */
-      outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
+      r = GETJSAMPLE(inptr0[col]);
+      g = GETJSAMPLE(inptr1[col]);
+      b = GETJSAMPLE(inptr2[col]);
+      /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
+       * (modulo) operator is equivalent to the bitmask operator AND.
+       */
+      outptr[RGB_RED]   = (JSAMPLE) ((r + g - CENTERJSAMPLE) & MAXJSAMPLE);
+      outptr[RGB_GREEN] = (JSAMPLE) g;
+      outptr[RGB_BLUE]  = (JSAMPLE) ((b + g - CENTERJSAMPLE) & MAXJSAMPLE);
       outptr += RGB_PIXELSIZE;
     }
   }
 }
 
+
 /*
- * YCCK->CMYK->CMY->RGB conversion.
- *
- * NB: this color conversion is introduced in jfx libjpeg snapshot as
- *     a part of the fix for RT-17000. In case of library upgrade, please
- *     check whether this convertor needs to be moved into upgraded version
- *     of the library.
+ * [R-G,G,B-G] to grayscale conversion with modulo calculation
+ * (inverse color transform).
  */
+
 METHODDEF(void)
-ycck_rgb_convert (j_decompress_ptr cinfo,
+rgb1_gray_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, k;
-  register int C, M, Y;
+  register INT32 * ctab = cconvert->rgb_y_tab;
   register int r, g, b;
   register JSAMPROW outptr;
-  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  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 * 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++) {
-      y  = GETJSAMPLE(inptr0[col]);
-      cb = GETJSAMPLE(inptr1[col]);
-      cr = GETJSAMPLE(inptr2[col]);
-      k  = GETJSAMPLE(inptr3[col]);
-
-      C = MAXJSAMPLE - (y + Crrtab[cr]);
-      M = MAXJSAMPLE - (y + ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS)));
-      Y = MAXJSAMPLE - (y + Cbbtab[cb]);
-
-      r = C * k / MAXJSAMPLE;
-      g = M * k / MAXJSAMPLE;
-      b = Y * k / MAXJSAMPLE;
-
-      /* Range-limiting is essential due to noise introduced by DCT losses. */
-      outptr[RGB_RED] = range_limit[r];
-      outptr[RGB_GREEN] = range_limit[g];
-      outptr[RGB_BLUE] = range_limit[b];
-
-      outptr += RGB_PIXELSIZE;
+      r = GETJSAMPLE(inptr0[col]);
+      g = GETJSAMPLE(inptr1[col]);
+      b = GETJSAMPLE(inptr2[col]);
+      /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
+       * (modulo) operator is equivalent to the bitmask operator AND.
+       */
+      r = (r + g - CENTERJSAMPLE) & MAXJSAMPLE;
+      b = (b + g - CENTERJSAMPLE) & MAXJSAMPLE;
+      /* Y */
+      outptr[col] = (JSAMPLE)
+                ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
+                 >> SCALEBITS);
     }
   }
 }
 
+
 /*
- * CMYK->CMY->RGB conversion.
- *
- * NB: this color conversion is introduced in jfx libjpeg snapshot as
- *     a part of the fix for RT-17000. In case of library upgrade, please
- *     check whether this convertor needs to be moved into upgraded version
- *     of the library.
+ * No colorspace change, but conversion from separate-planes
+ * to interleaved representation.
  */
+
 METHODDEF(void)
-cmyk_rgb_convert (j_decompress_ptr cinfo,
+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 c, m, y, k;
-  register int r, g, b;
   register JSAMPROW outptr;
-  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  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;
-  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++) {
-      c = GETJSAMPLE(inptr0[col]);
-      m = GETJSAMPLE(inptr1[col]);
-      y = GETJSAMPLE(inptr2[col]);
-      k = GETJSAMPLE(inptr3[col]);
-
-      r = c * k / MAXJSAMPLE;
-      g = m * k / MAXJSAMPLE;
-      b = y * k / MAXJSAMPLE;
-
-      /* Range-limiting is essential due to noise introduced by DCT losses. */
-      outptr[RGB_RED] = range_limit[r];
-      outptr[RGB_GREEN] = range_limit[g];
-      outptr[RGB_BLUE] = range_limit[b];
+      /* We can dispense with GETJSAMPLE() here */
+      outptr[RGB_RED]   = inptr0[col];
+      outptr[RGB_GREEN] = inptr1[col];
+      outptr[RGB_BLUE]  = inptr2[col];
+      outptr += RGB_PIXELSIZE;
+    }
+  }
+}
+
+
+/*
+ * 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)
+{
+  int ci;
+  register int nc = cinfo->num_components;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    for (ci = 0; ci < nc; ci++) {
+      inptr = input_buf[ci][input_row];
+      outptr = output_buf[0] + ci;
+      for (col = 0; col < num_cols; col++) {
+        *outptr = *inptr++;     /* needn't bother with GETJSAMPLE() here */
+        outptr += nc;
+      }
+    }
+    input_row++;
+    output_buf++;
+  }
+}
+
+
+/*
+ * Color conversion for grayscale: just copy the data.
+ * This also works for YCC -> 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 outptr;
+  register JSAMPROW inptr;
+  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.

@@ -379,11 +538,13 @@
     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. */
+      /* Range-limiting is essential due to noise introduced by DCT losses,
+       * and for extended gamut encodings (sYCC).
+       */
       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 */

@@ -417,11 +578,11 @@
   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;
+  cinfo->cconvert = &cconvert->pub;
   cconvert->pub.start_pass = start_pass_dcolor;
 
   /* Make sure num_components agrees with jpeg_color_space */
   switch (cinfo->jpeg_color_space) {
   case JCS_GRAYSCALE:

@@ -429,10 +590,12 @@
       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
     break;
 
   case JCS_RGB:
   case JCS_YCbCr:
+  case JCS_BG_RGB:
+  case JCS_BG_YCC:
     if (cinfo->num_components != 3)
       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
     break;
 
   case JCS_CMYK:

@@ -445,56 +608,112 @@
     if (cinfo->num_components < 1)
       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
     break;
   }
 
+  /* Support color transform only for RGB colorspaces */
+  if (cinfo->color_transform &&
+      cinfo->jpeg_color_space != JCS_RGB &&
+      cinfo->jpeg_color_space != JCS_BG_RGB)
+    ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+
   /* 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) {
+    switch (cinfo->jpeg_color_space) {
+    case JCS_GRAYSCALE:
+    case JCS_YCbCr:
+    case JCS_BG_YCC:
       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
+      break;
+    case JCS_RGB:
+      switch (cinfo->color_transform) {
+      case JCT_NONE:
+        cconvert->pub.color_convert = rgb_gray_convert;
+        break;
+      case JCT_SUBTRACT_GREEN:
+        cconvert->pub.color_convert = rgb1_gray_convert;
+        break;
+      default:
+        ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+      }
+      build_rgb_y_table(cinfo);
+      break;
+    default:
       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) {
+    switch (cinfo->jpeg_color_space) {
+    case 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 if (cinfo->jpeg_color_space == JCS_YCCK) {
-      cconvert->pub.color_convert = ycck_rgb_convert;
+      break;
+    case JCS_YCbCr:
+      cconvert->pub.color_convert = ycc_rgb_convert;
       build_ycc_rgb_table(cinfo);
-    } else if (cinfo->jpeg_color_space == JCS_CMYK) {
-      cconvert->pub.color_convert = cmyk_rgb_convert;
-    } else {
+      break;
+    case JCS_BG_YCC:
+      cconvert->pub.color_convert = ycc_rgb_convert;
+      build_bg_ycc_rgb_table(cinfo);
+      break;
+    case JCS_RGB:
+      switch (cinfo->color_transform) {
+      case JCT_NONE:
+        cconvert->pub.color_convert = rgb_convert;
+        break;
+      case JCT_SUBTRACT_GREEN:
+        cconvert->pub.color_convert = rgb1_rgb_convert;
+        break;
+      default:
+        ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+      }
+      break;
+    default:
       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
     }
     break;
 
+  case JCS_BG_RGB:
+    cinfo->out_color_components = RGB_PIXELSIZE;
+    if (cinfo->jpeg_color_space == JCS_BG_RGB) {
+      switch (cinfo->color_transform) {
+      case JCT_NONE:
+        cconvert->pub.color_convert = rgb_convert;
+        break;
+      case JCT_SUBTRACT_GREEN:
+        cconvert->pub.color_convert = rgb1_rgb_convert;
+        break;
+      default:
+        ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+      }
+    } else
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    break;
+
   case JCS_CMYK:
     cinfo->out_color_components = 4;
-    if (cinfo->jpeg_color_space == JCS_YCCK) {
+    switch (cinfo->jpeg_color_space) {
+    case JCS_YCCK:
       cconvert->pub.color_convert = ycck_cmyk_convert;
       build_ycc_rgb_table(cinfo);
-    } else if (cinfo->jpeg_color_space == JCS_CMYK) {
+      break;
+    case JCS_CMYK:
       cconvert->pub.color_convert = null_convert;
-    } else
+      break;
+    default:
       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    }
     break;
 
   default:
     /* Permit null conversion to same output space */
     if (cinfo->out_color_space == cinfo->jpeg_color_space) {
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