The Independent JPEG Group's JPEG software v1

1991-10-07 00:00:00 +00:00
commit 2cbeb8abd9
53 changed files with 13965 additions and 0 deletions
--- a/jdcolor.c
+++ b/jdcolor.c
@@ -0,0 +1,194 @@
+/*
+ * jdcolor.c
+ *
+ * Copyright (C) 1991, Thomas G. Lane.
+ * 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.
+ * These routines are invoked via the methods color_convert
+ * and colorout_init/term.
+ */
+
+#include "jinclude.h"
+
+
+/*
+ * Initialize for colorspace conversion.
+ */
+
+METHODDEF void
+colorout_init (decompress_info_ptr cinfo)
+{
+  /* no work needed */
+}
+
+
+/*
+ * Convert some rows of samples to the output colorspace.
+ * This version handles YCbCr -> RGB conversion.
+ * 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.
+ */
+
+METHODDEF void
+ycc_rgb_convert (decompress_info_ptr cinfo, int num_rows,
+		 JSAMPIMAGE input_data, JSAMPIMAGE output_data)
+{
+  register INT32 y, u, v, x;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JSAMPROW outptr0, outptr1, outptr2;
+  register long col;
+  register long width = cinfo->image_width;
+  register int row;
+  
+  for (row = 0; row < num_rows; row++) {
+    inptr0 = input_data[0][row];
+    inptr1 = input_data[1][row];
+    inptr2 = input_data[2][row];
+    outptr0 = output_data[0][row];
+    outptr1 = output_data[1][row];
+    outptr2 = output_data[2][row];
+    for (col = width; col > 0; col--) {
+      y = GETJSAMPLE(*inptr0++);
+      u = (int) GETJSAMPLE(*inptr1++) - CENTERJSAMPLE;
+      v = (int) GETJSAMPLE(*inptr2++) - CENTERJSAMPLE;
+      /* Note: if the inputs were computed directly from RGB values,
+       * range-limiting would be unnecessary here; but due to possible
+       * noise in the DCT/IDCT phase, we do need to apply range limits.
+       */
+      y *= 1024;	/* in case compiler can't spot common subexpression */
+      x = y          + 1436*v + 512; /* red */
+      if (x < 0) x = 0;
+      if (x > ((INT32) MAXJSAMPLE*1024)) x = (INT32) MAXJSAMPLE*1024;
+      *outptr0++ = x >> 10;
+      x = y -  352*u -  731*v + 512; /* green */
+      if (x < 0) x = 0;
+      if (x > ((INT32) MAXJSAMPLE*1024)) x = (INT32) MAXJSAMPLE*1024;
+      *outptr1++ = x >> 10;
+      x = y + 1815*u          + 512; /* blue */
+      if (x < 0) x = 0;
+      if (x > ((INT32) MAXJSAMPLE*1024)) x = (INT32) MAXJSAMPLE*1024;
+      *outptr2++ = x >> 10;
+    }
+  }
+}
+
+
+/*
+ * Color conversion for no colorspace change: just copy the data.
+ */
+
+METHODDEF void
+null_convert (decompress_info_ptr cinfo, int num_rows,
+	      JSAMPIMAGE input_data, JSAMPIMAGE output_data)
+{
+  short ci;
+
+  for (ci = 0; ci < cinfo->num_components; ci++) {
+    jcopy_sample_rows(input_data[ci], 0, output_data[ci], 0,
+		      num_rows, cinfo->image_width);
+  }
+}
+
+
+/*
+ * Color conversion for grayscale: just copy the data.
+ * This also works for YCbCr/YIQ -> grayscale conversion, in which
+ * we just copy the Y (luminance) component and ignore chrominance.
+ */
+
+METHODDEF void
+grayscale_convert (decompress_info_ptr cinfo, int num_rows,
+		   JSAMPIMAGE input_data, JSAMPIMAGE output_data)
+{
+  jcopy_sample_rows(input_data[0], 0, output_data[0], 0,
+		    num_rows, cinfo->image_width);
+}
+
+
+/*
+ * Finish up at the end of the file.
+ */
+
+METHODDEF void
+colorout_term (decompress_info_ptr cinfo)
+{
+  /* no work needed */
+}
+
+
+/*
+ * The method selection routine for output colorspace conversion.
+ */
+
+GLOBAL void
+jseldcolor (decompress_info_ptr cinfo)
+{
+  /* Make sure num_components agrees with jpeg_color_space */
+  switch (cinfo->jpeg_color_space) {
+  case CS_GRAYSCALE:
+    if (cinfo->num_components != 1)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    break;
+
+  case CS_RGB:
+  case CS_YIQ:
+  case CS_YCbCr:
+    if (cinfo->num_components != 3)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    break;
+
+  case CS_CMYK:
+    if (cinfo->num_components != 4)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    break;
+
+  default:
+    ERREXIT(cinfo->emethods, "Unsupported JPEG colorspace");
+    break;
+  }
+
+  /* Set color_out_comps and conversion method based on requested space */
+  switch (cinfo->out_color_space) {
+  case CS_GRAYSCALE:
+    cinfo->color_out_comps = 1;
+    if (cinfo->jpeg_color_space == CS_GRAYSCALE ||
+	cinfo->jpeg_color_space == CS_YCbCr ||
+	cinfo->jpeg_color_space == CS_YIQ)
+      cinfo->methods->color_convert = grayscale_convert;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  case CS_RGB:
+    cinfo->color_out_comps = 3;
+    if (cinfo->jpeg_color_space == CS_YCbCr)
+      cinfo->methods->color_convert = ycc_rgb_convert;
+    else if (cinfo->jpeg_color_space == CS_RGB)
+      cinfo->methods->color_convert = null_convert;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  case CS_CMYK:
+    cinfo->color_out_comps = 4;
+    if (cinfo->jpeg_color_space == CS_CMYK)
+      cinfo->methods->color_convert = null_convert;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  default:
+    ERREXIT(cinfo->emethods, "Unsupported output colorspace");
+    break;
+  }
+
+  if (cinfo->quantize_colors)
+    cinfo->final_out_comps = 1;	/* single colormapped output component */
+  else
+    cinfo->final_out_comps = cinfo->color_out_comps;
+
+  cinfo->methods->colorout_init = colorout_init;
+  cinfo->methods->colorout_term = colorout_term;
+}