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| author | Tor Andersson <tor.andersson@artifex.com> | 2011-12-07 22:28:31 +0100 |
|---|---|---|
| committer | Robin Watts <robin.watts@artifex.com> | 2011-12-08 11:42:57 +0000 |
| commit | 164ae7a63b56da5a1a2cf63701583753aa433762 (patch) | |
| tree | 18e376f41142798c49a3849729a84e6a587dc9e2 /fitz/res_pixmap.c | |
| parent | 7a6b60d0ec1abac316917690878011c3228a6fb7 (diff) | |
| download | mupdf-164ae7a63b56da5a1a2cf63701583753aa433762.tar.xz | |
Undo pre-multiplied alpha when saving PNG with alpha channels.
Diffstat (limited to 'fitz/res_pixmap.c')
| -rw-r--r-- | fitz/res_pixmap.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/fitz/res_pixmap.c b/fitz/res_pixmap.c index 83f46526..b1f151c3 100644 --- a/fitz/res_pixmap.c +++ b/fitz/res_pixmap.c @@ -226,6 +226,26 @@ fz_premultiply_pixmap(fz_pixmap *pix) } } +void +fz_unmultiply_pixmap(fz_pixmap *pix) +{ + unsigned char *s = pix->samples; + int a, inva; + int k, x, y; + + for (y = 0; y < pix->h; y++) + { + for (x = 0; x < pix->w; x++) + { + a = s[pix->n - 1]; + inva = a ? 255 * 256 / a : 0; + for (k = 0; k < pix->n - 1; k++) + s[k] = (s[k] * inva) >> 8; + s += pix->n; + } + } +} + fz_pixmap * fz_alpha_from_gray(fz_pixmap *gray, int luminosity) { |