int im_simcontr( image, xsize, ysize ) IMAGE *image; int xsize, ysize;
creates an unsigned char one band grey scale image of sizes xsize by ysize.
The created pattern consists of two neighbouring squares one dark (left
square) and one light (right square). The left
one contains a smaller light square and the right
one contains a darker square.
The function returns 0 on success and -1 on error.