private void FilterRowSub() { int i, j; for (i = 1; i <= ImgInfo.BytesPixel; i++) { rowbfilter[i] = (byte)rowb[i]; } for (j = 1, i = ImgInfo.BytesPixel + 1; i <= ImgInfo.BytesPerRow; i++, j++) { rowbfilter[i] = (byte)(rowb[i] - rowb[j]); } }