--- Convert.c.bak	Sun Dec 03 12:37:26 2006
+++ Convert.c	Sat Mar 14 09:22:51 2009
@@ -309,12 +309,38 @@
 rgb2cmyk(UINT8* out, const UINT8* in, int xsize)
 {
     int x;
-    for (x = 0; x < xsize; x++) {
-	/* Note: no undercolour removal */
-        *out++ = ~(*in++);
-        *out++ = ~(*in++);
-        *out++ = ~(*in++);
-        *out++ = 0; in++;
+    int R;
+    int G;
+    int B;
+    float C;
+    float M;
+    float Y;
+    int K;
+    for (x = 0; x < xsize; x++, in += 4) {
+			R = in[0];
+			G = in[1];
+			B = in[2];
+			
+			C = 255 - R;
+			M = 255 - G;
+			Y = 255 - B;
+			K = 255;
+			if (C < K) { K = C; }
+			if (M < K) { K = M; }
+			if (Y < K) { K = Y; }
+			if (K < 255) {
+				C = (C - K) / (255 - K) * 255;
+				M = (M - K) / (255 - K) * 255;
+				Y = (Y - K) / (255 - K) * 255;
+			} else {
+				C = 0;
+				M = 0;
+				Y = 0;
+			}
+			*out++ = C;
+			*out++ = M;
+			*out++ = Y;
+			*out++ = K;
     }
 }
 
@@ -322,11 +348,24 @@
 cmyk2rgb(UINT8* out, const UINT8* in, int xsize)
 {
     int x;
+    float C;
+    float M;
+    float Y;
+    int K;
     for (x = 0; x < xsize; x++, in += 4) {
-        *out++ = CLIP(255 - (in[0] + in[3]));
-	*out++ = CLIP(255 - (in[1] + in[3]));
-	*out++ = CLIP(255 - (in[2] + in[3]));
-	*out++ = 255;
+			C = in[0];
+			M = in[1];
+			Y = in[2];
+			K = in[3];
+			if (K > 0) {
+				C = (C / 255) * (255 - K) + K;
+				M = (M / 255) * (255 - K) + K;
+				Y = (Y / 255) * (255 - K) + K;
+			}
+			*out++ = 255 - C;
+			*out++ = 255 - M;
+			*out++ = 255 - Y;
+			*out++ = 255;
     }
 }