use image::{
    DynamicImage, GrayImage,
    imageops::{self, colorops},
};
pub fn auto_brighten(gray: &mut GrayImage) -> () {
    let avg = gray.pixels().map(|p| p.0[0] as u32).sum::<u32>() / gray.len() as u32;

    if avg < 100 {
        colorops::brighten_in_place(gray, 40);
        colorops::contrast_in_place(gray, 25.0);
    } else if avg > 180 {
        colorops::brighten_in_place(gray, -15);
    }
}

pub fn dither(gray: &mut GrayImage) -> Vec<u8> {
    imageops::dither(gray, &imageops::colorops::BiLevel);

    let (w, h) = (gray.width() as usize, gray.height() as usize);
    let pitch = (w + 7) >> 3;
    let mut bits = vec![0u8; pitch * h];

    for y in 0..h {
        for x in 0..w {
            let byte = y * pitch + (x >> 3);
            let bit = 7 - (x & 7);
            if gray[(x as u32, y as u32)].0[0] == 0 {
                bits[byte] |= 1 << bit;
            }
        }
    }
    bits
}