--- hplip-3.11.3a/prnt/hpcups/HPCupsFilter.cpp.bak	2011-05-15 11:31:59.535092724 +0200
+++ hplip-3.11.3a/prnt/hpcups/HPCupsFilter.cpp	2011-05-15 11:34:39.450480869 +0200
@@ -683,10 +683,18 @@
             if (b != 0 && b != 0xFF) {
 
 #ifdef __linux
-                rgb[0] -= (255 - b);
-                rgb[1] -= (255 - b);
-                rgb[2] -= (255 - b);
-                
+              //  rgb[0] -= (255 - b);
+              //  rgb[1] -= (255 - b);
+              //  rgb[2] -= (255 - b);
+              int cr,cg,cb;
+              cr = rgb[0] - (int)(255 - b);
+              rgb[0] = cr >= 0 ? cr : 0;
+
+              cg = rgb[1] - (int)(255 - b);
+              rgb[1] = cg >= 0 ? cg : 0;
+
+              cb = rgb[2] - (int)(255 - b);
+              rgb[2] = cb >= 0 ? cb : 0;  
 #else  // This alternate path is for Mac....
 
                 rgb[0] &= b;