+
+ RgbImage *ri= alloc_rgb_image(page0_rgbimage->w, page0_rgbimage->h);
+ const unsigned char *srcp;
+ unsigned char *destp, *endp;
+ for (srcp=page0_rgbimage->data, destp=ri->data,
+ endp= ri->data + 3 * ri->w * ri->h;
+ destp < endp;
+ srcp++, destp++) {
+ unsigned char c= *srcp & 0xf0;
+ *destp= c | (c>>4);
+ }