Horizontal pass, inner loops count

loops-to-unfold.c

for (yy = 0; yy < imOut->ysize; yy++) {
    // ...
    for (xx = 0; xx < imOut->xsize; xx++) {
        // ...
        for (b = 0; b < imIn->bands; b++) {
            // ...
            for (x = (int) xmin; x < (int) xmax; x++) {
                ss = ss + (UINT8) imIn->image[yy][x*4+b] * k[x - (int) xmin];
            }
        }
    }
}