Function encode 

pub fn encode(
    width: usize,
    height: usize,
    comps: usize,
    bits: u32,
    psv: u32,
    samples: &[u16],
) -> Vec<u8> 

Encode samples (height rows of width * comps interleaved values) as a lossless JPEG with predictor psv (1..=7) and a fixed Huffman table.