Function luminance

tools/bloom-diff/src/main.rs:58–60

(rgb: [f32; 3])

}

fn luminance(rgb: [f32; 3]) -> f32 {
    0.2126 * rgb[0] + 0.7152 * rgb[1] + 0.0722 * rgb[2]
}

/// Load an RGB image as normalized linear f32 triples. We operate in
/// gamma-encoded (sRGB byte) space rather than re-linearizing — the