encode.rs

fn encode_png_image(image: DynamicImage) -> Result<Vec<u8>, ImageError> {
    let mut result: Vec<u8> = Vec::new(); // Creates the output `Vec<u8>`

    image.write_to(&mut result, ImageOutputFormat::PNG)?; // Writes `image` to `result` as a PNG

    Ok(result)
}

fn main() {
    lambda::gateway::start(|req| {
        //...
      
        let thumbnail = image.thumbnail(128, 128);

        let encoded_thumbnail = encode_png_image(thumbnail)?; // Encode image as PNG
        let encoded_thumbnail = base64::encode(&encoded_thumbnail); // Encode PNG as base64
      
        //...
    })
}