Function channel

src/apps/cli/src/ui/theme.rs:577–584

(v: u8)

fn relative_luminance(r: u8, g: u8, b: u8) -> f64 {
    fn channel(v: u8) -> f64 {
        let v = v as f64 / 255.0;
        if v <= 0.03928 {
            v / 12.92
        } else {
            ((v + 0.055) / 1.055).powf(2.4)
        }
    }

    0.2126 * channel(r) + 0.7152 * channel(g) + 0.0722 * channel(b)
}