• Rule 90 in a square 100x100 image with a pseudorandom starting seed
• first saved as a .pbm file I later converted to .webp using an image viewer application
• I generated it with the following rust code …

use std::io::Write;

const WIDTH: usize = 100;
const HEIGHT: usize = 100;
type BITMAP = [[bool; WIDTH]; HEIGHT];
fn write_bitmap_file(filename: &str, bitmap: BITMAP) -> std::io::Result<()> {
    let mut file: std::fs::File = std::fs::File::create(filename)?;
    file.write_all(b"P1\n")?;
    file.write_all(format!("{} {}\n", WIDTH, HEIGHT).as_bytes())?;
    for y in 0..HEIGHT {
        let mut one_row = String::with_capacity(WIDTH + 1);
        for x in 0..WIDTH {
            if bitmap[y][x] {
                // one_row = format!("{}1", one_row);
                one_row.push('1');
            } else {
                one_row.push('0');
            }
        }
        one_row.push('\n');
        file.write_all(one_row.as_bytes())?;
    }
    Ok(())
}

fn applyrule(rulenr: u32, bitmap: &mut BITMAP) {
    for y in 1..HEIGHT {
        for x in 0..WIDTH {
            let mut rule_select = 0;
            for xpm in 0..3 {
                let addx = xpm as i32 - 1; // -1 to 1
                let idx: i32 = x as i32 + addx;
                if idx < 0 || idx == WIDTH as i32 {
                    continue;
                }
                let idx: usize = idx as usize;
                let reading = bitmap[y - 1][idx];
                if reading {
                    rule_select |= 1 << xpm;
                }
            }
            let rule_index = 1 << rule_select;
            if rulenr & rule_index != 0 {
                bitmap[y][x] = true;
            } else {
                bitmap[y][x] = false;
            }
        }
    }
}

fn main() {
    let randomseed: u128 = 0x46f470db4dbf5ac29b6e572f51ecafe;
    let mut bitmap: BITMAP = [[false; WIDTH]; HEIGHT];
    // populate first row width random values
    for x in 0..WIDTH {
        let xmod = x % 128;
        let curr = randomseed & (1 << xmod) == 0;
        bitmap[0][x] = curr;
    }
    applyrule(90, &mut bitmap);
    write_bitmap_file("rule90.bpm", bitmap).unwrap();
}