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| author | Sebastian Rasmussen <sebras@gmail.com> | 2017-04-30 14:41:59 +0800 |
|---|---|---|
| committer | Sebastian Rasmussen <sebras@gmail.com> | 2017-05-02 00:51:01 +0800 |
| commit | 6abb2ad2350cecbf8052fcbb52b71e6cf32cea7f (patch) | |
| tree | 43e0e2c3e68186b5d4e2b486cdcb3def0c7dee1e | |
| parent | b2c820e11bdec61fc38dde8d7d0fd3b35fc7ccfa (diff) | |
| download | mupdf-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.c | 25 |
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 * |