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extern crate jpeg_decoder as jpeg;
extern crate png;
use std::env;
use std::fs::File;
use std::io::{self, BufReader, Write};
use std::process;
fn usage() -> ! {
write!(io::stderr(), "usage: decode image.jpg image.png").unwrap();
process::exit(1)
}
fn main() {
let mut args = env::args().skip(1);
let input_path = args.next().unwrap_or_else(|| usage());
let output_path = args.next().unwrap_or_else(|| usage());
let input_file = File::open(input_path).expect("The specified input file could not be opened");
let mut decoder = jpeg::Decoder::new(BufReader::new(input_file));
let mut data = decoder.decode().expect("Decoding failed. If other software can successfully decode the specified JPEG image, then it's likely that there is a bug in jpeg-decoder");
let info = decoder.info().unwrap();
eprintln!("{:?}", info);
eprintln!("Exif: {}", decoder.exif_data().is_some());
eprintln!("ICC: {}", decoder.icc_profile().is_some());
let output_file = File::create(output_path).unwrap();
let mut encoder = png::Encoder::new(output_file, info.width as u32, info.height as u32);
match info.pixel_format {
jpeg::PixelFormat::L16 => {
encoder.set_depth(png::BitDepth::Sixteen);
encoder.set_color(png::ColorType::Grayscale);
},
jpeg::PixelFormat::RGB24 => {
encoder.set_depth(png::BitDepth::Eight);
encoder.set_color(png::ColorType::RGB);
},
jpeg::PixelFormat::CMYK32 => {
data = cmyk_to_rgb(&mut data);
encoder.set_depth(png::BitDepth::Eight);
encoder.set_color(png::ColorType::RGB)
},
jpeg::PixelFormat::L8 => {
encoder.set_depth(png::BitDepth::Eight);
encoder.set_color(png::ColorType::Grayscale);
},
}
encoder.write_header()
.expect("writing png header failed")
.write_image_data(&data)
.expect("png encoding failed");
}
fn cmyk_to_rgb(input: &[u8]) -> Vec<u8> {
let size = input.len() - input.len() / 4;
let mut output = Vec::with_capacity(size);
for pixel in input.chunks(4) {
let c = pixel[0] as f32 / 255.0;
let m = pixel[1] as f32 / 255.0;
let y = pixel[2] as f32 / 255.0;
let k = pixel[3] as f32 / 255.0;
// CMYK -> CMY
let c = c * (1.0 - k) + k;
let m = m * (1.0 - k) + k;
let y = y * (1.0 - k) + k;
// CMY -> RGB
let r = (1.0 - c) * 255.0;
let g = (1.0 - m) * 255.0;
let b = (1.0 - y) * 255.0;
output.push(r as u8);
output.push(g as u8);
output.push(b as u8);
}
output
}
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