Function normalize 

pub fn normalize<T, const CHANNELS: usize>(
    input: ImageView<'_, T, CHANNELS>,
    scale: f32,
    mean: [f32; CHANNELS],
    std: [f32; CHANNELS],
) -> Result<Image<f32, CHANNELS>, VisionError>
where
    T: PixelComponent,

Converts packed scalar values to f32, then applies value * scale, mean subtraction, and per-channel standard-deviation normalization.