buf[bidx + i] = (buf[bidx + i] as i32
                            + ((fg[i] as i32 - buf[bidx + i] as i32) * data[sidx + i] as i32) / 255)
                            as u8;

                        let m = data[sidx] as u32;
                        let d = buf[bidx + i] as u32;
                        let s = fg[i] as u32;
                        let res = (d * (255 - m) + s * m) / 255;
                        buf[bidx + i] = res as u8;