The Independent JPEG Group's JPEG software v1
diff --git a/jccolor.c b/jccolor.c
new file mode 100644
index 0000000..7fd198c
--- /dev/null
+++ 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;
+}
