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/jccolor.c
+++ b/jccolor.c
@@ -0,0 +1,203 @@
+/*
+ * jccolor.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 input colorspace conversion routines.
+ * These routines are invoked via the methods get_sample_rows
+ * and colorin_init/term.
+ */
+
+#include "jinclude.h"
+
+
+static JSAMPARRAY pixel_row;	/* Workspace for a pixel row in input format */
+
+
+/*
+ * Initialize for colorspace conversion.
+ */
+
+METHODDEF void
+colorin_init (compress_info_ptr cinfo)
+{
+  /* Allocate a workspace for the result of get_input_row. */
+  pixel_row = (*cinfo->emethods->alloc_small_sarray)
+		(cinfo->image_width, (long) cinfo->input_components);
+}
+
+
+/*
+ * Fetch some rows of pixels from get_input_row and convert to the
+ * JPEG colorspace.
+ * This version handles RGB -> YCbCr 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
+get_rgb_ycc_rows (compress_info_ptr cinfo,
+		  int rows_to_read, JSAMPIMAGE image_data)
+{
+  register INT32 r, g, b;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JSAMPROW outptr0, outptr1, outptr2;
+  register long col;
+  long width = cinfo->image_width;
+  int row;
+
+  for (row = 0; row < rows_to_read; row++) {
+    /* Read one row from the source file */
+    (*cinfo->methods->get_input_row) (cinfo, pixel_row);
+    /* Convert colorspace */
+    inptr0 = pixel_row[0];
+    inptr1 = pixel_row[1];
+    inptr2 = pixel_row[2];
+    outptr0 = image_data[0][row];
+    outptr1 = image_data[1][row];
+    outptr2 = image_data[2][row];
+    for (col = width; col > 0; col--) {
+      r = GETJSAMPLE(*inptr0++);
+      g = GETJSAMPLE(*inptr1++);
+      b = GETJSAMPLE(*inptr2++);
+      /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
+       * must be too; do not need an explicit range-limiting operation.
+       */
+      /* Y */
+      *outptr0++ = (   306*r +  601*g +  117*b + (INT32) 512) >> 10;
+      /* Cb */
+      *outptr1++ = ((-173)*r -  339*g +  512*b + (INT32) 512*(MAXJSAMPLE+1)) >> 10;
+      /* Cr */
+      *outptr2++ = (   512*r -  429*g -   83*b + (INT32) 512*(MAXJSAMPLE+1)) >> 10;
+    }
+  }
+}
+
+
+/*
+ * Fetch some rows of pixels from get_input_row and convert to the
+ * JPEG colorspace.
+ * This version handles grayscale (no conversion).
+ */
+
+METHODDEF void
+get_grayscale_rows (compress_info_ptr cinfo,
+		    int rows_to_read, JSAMPIMAGE image_data)
+{
+  int row;
+
+  for (row = 0; row < rows_to_read; row++) {
+    /* Read one row from the source file */
+    (*cinfo->methods->get_input_row) (cinfo, pixel_row);
+    /* Convert colorspace (gamma mapping needed here) */
+    jcopy_sample_rows(pixel_row, 0, image_data[0], row,
+		      1, cinfo->image_width);
+  }
+}
+
+
+/*
+ * Fetch some rows of pixels from get_input_row and convert to the
+ * JPEG colorspace.
+ * This version handles multi-component colorspaces without conversion.
+ */
+
+METHODDEF void
+get_noconvert_rows (compress_info_ptr cinfo,
+		    int rows_to_read, JSAMPIMAGE image_data)
+{
+  int row, ci;
+
+  for (row = 0; row < rows_to_read; row++) {
+    /* Read one row from the source file */
+    (*cinfo->methods->get_input_row) (cinfo, pixel_row);
+    /* Convert colorspace (gamma mapping needed here) */
+    for (ci = 0; ci < cinfo->input_components; ci++) {
+      jcopy_sample_rows(pixel_row, ci, image_data[ci], row,
+			1, cinfo->image_width);
+    }
+  }
+}
+
+
+/*
+ * Finish up at the end of the file.
+ */
+
+METHODDEF void
+colorin_term (compress_info_ptr cinfo)
+{
+  /* Release the workspace. */
+  (*cinfo->emethods->free_small_sarray)
+		(pixel_row, (long) cinfo->input_components);
+}
+
+
+/*
+ * The method selection routine for input colorspace conversion.
+ */
+
+GLOBAL void
+jselccolor (compress_info_ptr cinfo)
+{
+  /* Make sure input_components agrees with in_color_space */
+  switch (cinfo->in_color_space) {
+  case CS_GRAYSCALE:
+    if (cinfo->input_components != 1)
+      ERREXIT(cinfo->emethods, "Bogus input colorspace");
+    break;
+
+  case CS_RGB:
+    if (cinfo->input_components != 3)
+      ERREXIT(cinfo->emethods, "Bogus input colorspace");
+    break;
+
+  case CS_CMYK:
+    if (cinfo->input_components != 4)
+      ERREXIT(cinfo->emethods, "Bogus input colorspace");
+    break;
+
+  default:
+    ERREXIT(cinfo->emethods, "Unsupported input colorspace");
+    break;
+  }
+
+  /* Check num_components, set conversion method based on requested space */
+  switch (cinfo->jpeg_color_space) {
+  case CS_GRAYSCALE:
+    if (cinfo->num_components != 1)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    if (cinfo->in_color_space == CS_GRAYSCALE)
+      cinfo->methods->get_sample_rows = get_grayscale_rows;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  case CS_YCbCr:
+    if (cinfo->num_components != 3)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    if (cinfo->in_color_space == CS_RGB)
+      cinfo->methods->get_sample_rows = get_rgb_ycc_rows;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  case CS_CMYK:
+    if (cinfo->num_components != 4)
+      ERREXIT(cinfo->emethods, "Bogus JPEG colorspace");
+    if (cinfo->in_color_space == CS_CMYK)
+      cinfo->methods->get_sample_rows = get_noconvert_rows;
+    else
+      ERREXIT(cinfo->emethods, "Unsupported color conversion request");
+    break;
+
+  default:
+    ERREXIT(cinfo->emethods, "Unsupported JPEG colorspace");
+    break;
+  }
+
+  cinfo->methods->colorin_init = colorin_init;
+  cinfo->methods->colorin_term = colorin_term;
+}