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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 | |
| parent | 7a6b60d0ec1abac316917690878011c3228a6fb7 (diff) | |
| download | mupdf-164ae7a63b56da5a1a2cf63701583753aa433762.tar.xz | |
Undo pre-multiplied alpha when saving PNG with alpha channels.
| -rw-r--r-- | apps/pdfdraw.c | 3 | ||||
| -rw-r--r-- | fitz/fitz.h | 1 | ||||
| -rw-r--r-- | fitz/res_pixmap.c | 20 |
3 files changed, 24 insertions, 0 deletions
diff --git a/apps/pdfdraw.c b/apps/pdfdraw.c index d79cd75c..9ad2b56c 100644 --- a/apps/pdfdraw.c +++ b/apps/pdfdraw.c @@ -189,6 +189,9 @@ static void drawpage(pdf_xref *xref, int pagenum) if (gamma_value != 1) fz_gamma_pixmap(pix, gamma_value); + if (savealpha) + fz_unmultiply_pixmap(pix); + if (output) { char buf[512]; diff --git a/fitz/fitz.h b/fitz/fitz.h index ccaa98b8..d0054f3e 100644 --- a/fitz/fitz.h +++ b/fitz/fitz.h @@ -626,6 +626,7 @@ void fz_clear_pixmap_with_color(fz_pixmap *pix, int value); void fz_clear_pixmap_rect_with_color(fz_pixmap *pix, int value, fz_bbox r); void fz_copy_pixmap_rect(fz_pixmap *dest, fz_pixmap *src, fz_bbox r); void fz_premultiply_pixmap(fz_pixmap *pix); +void fz_unmultiply_pixmap(fz_pixmap *pix); fz_pixmap *fz_alpha_from_gray(fz_pixmap *gray, int luminosity); fz_bbox fz_bound_pixmap(fz_pixmap *pix); void fz_invert_pixmap(fz_pixmap *pix); 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) { |