otf-pixels-codec-jpeg

JPEG for Pixels, baseline written from scratch

crates.io | Docs | Pixels

An Open Tech Foundation project

Baseline JPEG decode and encode, streaming one MCU row at a time. Decoding at 1/2, 1/4 or 1/8 scale makes thumbnails of large photos cheap.

[!TIP] Building an app or a server? Use otf-pixels instead: it picks this codec from the file's bytes with its jpeg feature.

Use it

Transcode row by row, without holding the image:

use otf_pixels_codec_jpeg::{JpegDecoder, JpegEncoder};
use otf_pixels_core::{Decoder, Encoder, Limits};
use otf_pixels_codec_jpeg::{Scale, Subsampling};

let file = std::fs::File::open("photo.jpg")?;
let mut decoder = JpegDecoder::with_scale(file, Limits::default(), Scale::Quarter)?;
let descriptor = decoder.descriptor();
let mut encoder = JpegEncoder::with_quality(85)?.with_subsampling(Subsampling::Both);
let mut out = Vec::new();
encoder.write_header(&descriptor, &mut out)?;
let mut row = vec![0; descriptor.row_bytes()];
for _ in 0..descriptor.height {
    decoder.read_row(&mut row)?;
    encoder.write_row(&row, &mut out)?;
}
encoder.finish(&mut out)?;

Capabilities

API

Part of Pixels

License

Apache-2.0 — see LICENSE.