I have looked at wrc code and there is a strange 100K limit on the size of mem allocation : assert(size > 0); assert(size < 102400); res = malloc(size); if(res == NULL) { Baffling code - hardcoded limit hidden in a C file :-/ I removed the assert and wrc was able to handle a 1 megabyte bitmap. Anyone has an idea about the meaning of this limit ? Gerard