Don't apply default decode array to ICC Lab image data.

Adjust the decode array to allow for the fact that the default
decode is done by the ICC code.

2 files changed, 15 insertions, 2 deletions

diff --git a/source/fitz/colorspace.c b/source/fitz/colorspace.c
index ceec805e..9d5c93ab 100644
--- a/source/fitz/colorspace.c
+++ b/source/fitz/colorspace.c
@@ -679,7 +679,7 @@ clamp_lab(const fz_colorspace *cs, const float *src, float *dst)
 		dst[i] = fz_clamp(src[i], i ? -128 : 0, i ? 127 : 100);
 }
 
-static int fz_colorspace_is_lab(fz_context *ctx, const fz_colorspace *cs)
+int fz_colorspace_is_lab(fz_context *ctx, const fz_colorspace *cs)
 {
 	return cs && cs->to_ccs == lab_to_rgb;
 }
diff --git a/source/fitz/image.c b/source/fitz/image.c
index 2e59e401..b4fd2112 100644
--- a/source/fitz/image.c
+++ b/source/fitz/image.c
@@ -803,9 +803,22 @@ fz_new_image_of_size(fz_context *ctx, int w, int h, int bpc, fz_colorspace *colo
 			image->decode[2*i+1] = maxval;
 		}
 	}
+	/* ICC spaces have the default decode arrays pickled into them.
+	 * For most spaces this is fine, because [ 0 1 0 1 0 1 ] is
+	 * idempotent. For Lab, however, we need to adjust it. */
+	if (fz_colorspace_is_lab_icc(ctx, colorspace))
+	{
+		/* Undo the default decode array of [0 100 -128 127 -128 127] */
+		image->decode[0] = image->decode[0]/100.0f;
+		image->decode[1] = image->decode[1]/100.0f;
+		image->decode[2] = (image->decode[2]+128)/255.0f;
+		image->decode[3] = (image->decode[3]+128)/255.0f;
+		image->decode[4] = (image->decode[4]+128)/255.0f;
+		image->decode[5] = (image->decode[5]+128)/255.0f;
+	}
 	for (i = 0; i < image->n; i++)
 	{
-		if (image->decode[i * 2] * 255 != 0 || image->decode[i * 2 + 1] * 255 != 255)
+		if (image->decode[i * 2] != 0 || image->decode[i * 2 + 1] != 1)
 			break;
 	}
 	if (i != image->n)