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authorSebastian Rasmussen <sebras@gmail.com>2017-04-30 14:41:59 +0800
committerSebastian Rasmussen <sebras@gmail.com>2017-05-02 00:51:01 +0800
commit6abb2ad2350cecbf8052fcbb52b71e6cf32cea7f (patch)
tree43e0e2c3e68186b5d4e2b486cdcb3def0c7dee1e
parentb2c820e11bdec61fc38dde8d7d0fd3b35fc7ccfa (diff)
downloadmupdf-6abb2ad2350cecbf8052fcbb52b71e6cf32cea7f.tar.xz
tiff: Scale Lab components to suit colorspace.
TIFF already provides the a/b components prescaled. Previously the colorspace color conversion process scaled them again, causing out of range behaviour.
-rw-r--r--source/fitz/load-tiff.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/source/fitz/load-tiff.c b/source/fitz/load-tiff.c
index c8449dc9..a6c1cefe 100644
--- a/source/fitz/load-tiff.c
+++ b/source/fitz/load-tiff.c
@@ -937,6 +937,24 @@ tiff_swap_byte_order(unsigned char *buf, int n)
}
static void
+tiff_scale_lab_samples(fz_context *ctx, unsigned char *buf, int bps, int n)
+{
+ int i;
+ if (bps == 8)
+ for (i = 0; i < n; i++, buf += 3)
+ {
+ buf[1] ^= 128;
+ buf[2] ^= 128;
+ }
+ else if (bps == 16)
+ for (i = 0; i < n; i++, buf += 6)
+ {
+ buf[2] ^= 128;
+ buf[4] ^= 128;
+ }
+}
+
+static void
tiff_read_header(fz_context *ctx, struct tiff *tiff, unsigned char *buf, size_t len)
{
unsigned version;
@@ -1257,6 +1275,13 @@ tiff_decode_samples(fz_context *ctx, struct tiff *tiff)
/* Byte swap 16-bit images to big endian if necessary */
if (tiff->bitspersample == 16 && tiff->order == TII)
tiff_swap_byte_order(tiff->samples, tiff->imagewidth * tiff->imagelength * tiff->samplesperpixel);
+
+ /* Lab colorspace expects all sample components 0..255.
+ TIFF supplies them as L = 0..255, a/b = -128..127 (for
+ 8 bits per sample, -32768..32767 for 16 bits per sample)
+ Scale them to the colorspace's expectations. */
+ if (tiff->photometric == 8 && tiff->samplesperpixel == 3)
+ tiff_scale_lab_samples(ctx, tiff->samples, tiff->bitspersample, tiff->imagewidth * tiff->imagelength);
}
fz_pixmap *