Use the CMYK-to-RGB transform from Poppler.

1 files changed, 51 insertions, 14 deletions

diff --git a/fitz/res_colorspace.c b/fitz/res_colorspace.c
index ca3cdeb8..f3ea317d 100644
--- a/fitz/res_colorspace.c
+++ b/fitz/res_colorspace.c
@@ -85,20 +85,57 @@ static void xyztobgr(fz_colorspace *cs, float *xyz, float *bgr)
 
 static void cmyktoxyz(fz_colorspace *cs, float *cmyk, float *xyz)
 {
-#ifdef SLOWCMYK /* from xpdf */
-	float c = CLAMP(cmyk[0] + cmyk[3], 0, 1);
-	float m = CLAMP(cmyk[1] + cmyk[3], 0, 1);
-	float y = CLAMP(cmyk[2] + cmyk[3], 0, 1);
-	float aw = (1-c) * (1-m) * (1-y);
-	float ac = c * (1-m) * (1-y);
-	float am = (1-c) * m * (1-y);
-	float ay = (1-c) * (1-m) * y;
-	float ar = (1-c) * m * y;
-	float ag = c * (1-m) * y;
-	float ab = c * m * (1-y);
-	float r = aw + 0.9137*am + 0.9961*ay + 0.9882*ar;
-	float g = aw + 0.6196*ac + ay + 0.5176*ag;
-	float b = aw + 0.7804*ac + 0.5412*am + 0.0667*ar + 0.2118*ag + 0.4863*ab;
+#ifdef SLOWCMYK /* from poppler */
+	float c = cmyk[0], m = cmyk[1], y = cmyk[2], k = cmyk[3];
+	float c1 = 1 - c, m1 = 1 - m, y1 = 1 - y, k1 = 1 - k;
+	float r, g, b, x;
+
+	/* this is a matrix multiplication, unrolled for performance */
+	x = c1 * m1 * y1 * k1;	/* 0 0 0 0 */
+	r = g = b = x;
+	x = c1 * m1 * y1 * k;	/* 0 0 0 1 */
+	r += 0.1373 * x;
+	g += 0.1216 * x;
+	b += 0.1255 * x;
+	x = c1 * m1 * y * k1;	/* 0 0 1 0 */
+	r += x;
+	g += 0.9490 * x;
+	x = c1 * m1 * y * k;	/* 0 0 1 1 */
+	r += 0.1098 * x;
+	g += 0.1020 * x;
+	x = c1 * m * y1 * k1;	/* 0 1 0 0 */
+	r += 0.9255 * x;
+	b += 0.5490 * x;
+	x = c1 * m * y1 * k;	/* 0 1 0 1 */
+	r += 0.1412 * x;
+	x = c1 * m * y * k1;	/* 0 1 1 0 */
+	r += 0.9294 * x;
+	g += 0.1098 * x;
+	b += 0.1412 * x;
+	x = c1 * m * y * k;	/* 0 1 1 1 */
+	r += 0.1333 * x;
+	x = c * m1 * y1 * k1;	/* 1 0 0 0 */
+	g += 0.6784 * x;
+	b += 0.9373 * x;
+	x = c * m1 * y1 * k;	/* 1 0 0 1 */
+	g += 0.0588 * x;
+	b += 0.1412 * x;
+	x = c * m1 * y * k1;	/* 1 0 1 0 */
+	g += 0.6510 * x;
+	b += 0.3137 * x;
+	x = c * m1 * y * k;	/* 1 0 1 1 */
+	g += 0.0745 * x;
+	x = c * m * y1 * k1;	/* 1 1 0 0 */
+	r += 0.1804 * x;
+	g += 0.1922 * x;
+	b += 0.5725 * x;
+	x = c * m * y1 * k;	/* 1 1 0 1 */
+	b += 0.0078 * x;
+	x = c * m * y * k1;	/* 1 1 1 0 */
+	r += 0.2118 * x;
+	g += 0.2119 * x;
+	b += 0.2235 * x;
+
 	xyz[0] = CLAMP(r, 0, 1);
 	xyz[1] = CLAMP(g, 0, 1);
 	xyz[2] = CLAMP(b, 0, 1);