1 files changed, 35 insertions, 0 deletions
diff --git a/libmscgen/gd_color.c b/libmscgen/gd_color.c
new file mode 100644
index 0000000..ba0efd8
--- /dev/null
+++ b/libmscgen/gd_color.c
@@ -0,0 +1,35 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gd.h"
+#include "gd_color.h"
+
+/**
+ * The threshold method works relatively well but it can be improved.
+ * Maybe L*a*b* and Delta-E will give better results (and a better
+ * granularity).
+ */
+int gdColorMatch(gdImagePtr im, int col1, int col2, float threshold)
+{
+	const int dr = gdImageRed(im, col1) - gdImageRed(im, col2);
+	const int dg = gdImageGreen(im, col1) - gdImageGreen(im, col2);
+	const int db = gdImageBlue(im, col1) - gdImageBlue(im, col2);
+	const int da = gdImageAlpha(im, col1) - gdImageAlpha(im, col2);
+	const int dist = dr * dr + dg * dg + db * db + da * da;
+
+	return (100.0 * dist / 195075) < threshold;
+}
+
+/*
+ * To be implemented when we have more image formats.
+ * Buffer like gray8 gray16 or rgb8 will require some tweak
+ * and can be done in this function (called from the autocrop
+ * function. (Pierre)
+ */
+#if 0
+static int colors_equal (const int col1, const in col2)
+{
+
+}
+#endif