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| author | Tor Andersson <tor@ghostscript.com> | 2010-10-20 23:03:50 +0000 |
|---|---|---|
| committer | Tor Andersson <tor@ghostscript.com> | 2010-10-20 23:03:50 +0000 |
| commit | 3a67269b466ada017058faa8ebed2df10f12c5f4 (patch) | |
| tree | c97bfb36f91f30030aeeb6ee0c2d1d02d721ea6f | |
| parent | ebf0fd7b216f3753e4c7f4ae3e8f1ce4b03e00c6 (diff) | |
| download | mupdf-3a67269b466ada017058faa8ebed2df10f12c5f4.tar.xz | |
Fix Lab colorspace conversions.
| -rw-r--r-- | fitz/res_colorspace.c | 2 | ||||
| -rw-r--r-- | mupdf/pdf_colorspace.c | 31 |
2 files changed, 16 insertions, 17 deletions
diff --git a/fitz/res_colorspace.c b/fitz/res_colorspace.c index 2ce4525a..f770bbcb 100644 --- a/fitz/res_colorspace.c +++ b/fitz/res_colorspace.c @@ -347,6 +347,8 @@ fz_stdconvpixmap(fz_pixmap *src, fz_pixmap *dst) srcn = ss->n; dstn = ds->n; + /* TODO: special case Lab colorspace (scaling of components to float) */ + /* Brute-force for small images */ if (src->w * src->h < 256) { diff --git a/mupdf/pdf_colorspace.c b/mupdf/pdf_colorspace.c index e0a3ab8e..447b3047 100644 --- a/mupdf/pdf_colorspace.c +++ b/mupdf/pdf_colorspace.c @@ -41,17 +41,14 @@ static inline float invg(float x) static void labtoxyz(fz_colorspace *cs, float *lab, float *xyz) { + /* input is in range (0..100, -128..127, -128..127) not (0..1, 0..1, 0..1) */ float lstar, astar, bstar, l, m, n; - float tmp[3]; - tmp[0] = lab[0] * 100; - tmp[1] = lab[1] * 200 - 100; - tmp[2] = lab[2] * 200 - 100; - lstar = tmp[0]; - astar = CLAMP(tmp[1], -100, 100); - bstar = CLAMP(tmp[2], -100, 100); - l = (lstar + 16) / 116 + astar / 500; + lstar = lab[0]; + astar = lab[1]; + bstar = lab[2]; m = (lstar + 16) / 116; - n = (lstar + 16) / 116 - bstar / 200; + l = m + astar / 500; + n = m - bstar / 200; xyz[0] = fung(l); xyz[1] = fung(m); xyz[2] = fung(n); @@ -60,17 +57,17 @@ labtoxyz(fz_colorspace *cs, float *lab, float *xyz) static void xyztolab(fz_colorspace *cs, float *xyz, float *lab) { - float tmp[3]; + float lstar, astar, bstar; float yyn = xyz[1]; if (yyn < 0.008856f) - tmp[0] = 116.0f * yyn * (1.0f / 3.0f) - 16.0f; + lstar = 116.0f * yyn * (1.0f / 3.0f) - 16.0f; else - tmp[0] = 903.3f * yyn; - tmp[1] = 500 * (invg(xyz[0]) - invg(xyz[1])); - tmp[2] = 200 * (invg(xyz[1]) - invg(xyz[2])); - lab[0] = tmp[0] / 100; - lab[1] = (tmp[1] + 100) / 200; - lab[2] = (tmp[2] + 100) / 200; + lstar = 903.3f * yyn; + astar = 500 * (invg(xyz[0]) - invg(xyz[1])); + bstar = 200 * (invg(xyz[1]) - invg(xyz[2])); + lab[0] = lstar; + lab[1] = astar; + lab[2] = bstar; } static fz_colorspace kdevicelab = { -1, "Lab", 3, labtoxyz, xyztolab }; |