[gs-cvs] rev 8287 - trunk/gs/src

[ray at ghostscript.com]

Author: ray
Date: 2007-10-11 09:36:26 -0700 (Thu, 11 Oct 2007)
New Revision: 8287

Modified:
   trunk/gs/src/gdevp14.c
Log:
Fix incorrect colors with transparency to cmyk+spot devices (such as tiffsep).
Bug 689494 for customer #190.

DETAILS:

CMYK + Spot colors are subtractive. The blending with the 'bg' color was
inverted, causing very strange colors.

Note that the pdf14_cmykspot_put_image is VERY inefficient and at the
very least should have logic added to write runs of the same color
as a wide rectangle (rather than the current 1x1 pixel rectangles).

EXPECTED DIFFERENCES:

None. There are no spot color devices currently in the regression testing.


Modified: trunk/gs/src/gdevp14.c
===================================================================
--- trunk/gs/src/gdevp14.c	2007-10-10 23:02:18 UTC (rev 8286)
+++ trunk/gs/src/gdevp14.c	2007-10-11 16:36:26 UTC (rev 8287)
@@ -1422,7 +1422,7 @@
 		a ^= 0xff;
 		for (comp_num = 0; comp_num < num_known_comp; comp_num++) {
 		    comp  = buf_ptr[x + planestride * input_map[comp_num]];
-		    tmp = ((bg - comp) * a) + 0x80;
+		    tmp = ((comp - bg) * a) + 0x80;
 		    comp += tmp + (tmp >> 8);
 		    cv[output_map[comp_num]] = comp;
 		}