icy_sixel-cli-0.4.0 is not a library.

icy_sixel

A high-performance, 100% pure Rust implementation of a SIXEL encoder and decoder.

I wanted a pure Rust implementation to simplify deployment of my cross-platform applications. In version 0.4.0, I rewrote the encoder using quantette, a high-quality color quantization library licensed under MIT/Apache-2.0. It uses Wu's algorithm with Floyd-Steinberg dithering for excellent results.

The decoder is a clean-room implementation based on the SIXEL specification, with SIMD optimizations for maximum performance.

Features

SIXEL Encoder: High-quality color quantization with quantette (Wu's algorithm + Floyd-Steinberg dithering)
SIXEL Decoder: Clean-room implementation with RGBA output and SSE2 SIMD acceleration
Transparency Support: Full alpha channel handling in both encoder and decoder
Pure Rust: No C dependencies, easy to build and deploy
Cross-platform: Works on Linux, macOS, and Windows

Installation

Add this to your Cargo.toml:

[dependencies]
icy_sixel = "0.4"

Usage

Encoding an Image to SIXEL

use icy_sixel::{sixel_encode, EncodeOptions};

// RGBA image data (4 bytes per pixel)
let rgba = vec![
    255, 0, 0, 255,   // Red pixel
    0, 255, 0, 255,   // Green pixel
    0, 0, 255, 255,   // Blue pixel
];

let options = EncodeOptions::default();
let sixel = sixel_encode(&rgba, 3, 1, &options)?;
print!("{}", sixel);

Encoding with Custom Options

use icy_sixel::{sixel_encode, EncodeOptions};

let options = EncodeOptions {
    max_colors: 64,     // Use only 64 colors (2-256)
    quality: 100,       // Quality 0-100 (reserved for future use)
};

let sixel = sixel_encode(&rgba, width, height, &options)?;

Decoding SIXEL to Image Data

use icy_sixel::sixel_decode;

let sixel_data = b"\x1bPq#0;2;100;0;0#0~-\x1b\\";
let image = sixel_decode(sixel_data)?;
// image.rgba contains RGBA pixel data (4 bytes per pixel)
// image.width and image.height contain dimensions

CLI Tool

The crate includes a command-line tool for encoding and decoding:

# Install the CLI
cargo install icy_sixel

# Encode a PNG to SIXEL
sixel encode image.png -o output.six

# Encode with custom settings
sixel encode image.png -o output.six --colors 64

# Decode SIXEL to PNG
sixel decode image.six -o output.png

# Display image in terminal (requires SIXEL-capable terminal)
sixel show image.png

Architecture

Encoder

The encoder uses quantette for high-quality color quantization with Wu's algorithm and Floyd-Steinberg dithering. This produces excellent results, especially for images with gradients or complex color distributions.

Decoder

The decoder is a clean-room implementation derived from the SIXEL specification:

Returns RGBA buffers (4 bytes per pixel) for easy integration with graphics libraries
SIMD-accelerated horizontal span filling on x86/x86_64 (SSE2)
Optimized with color caching and loop unrolling
Comprehensive bounds checking prevents buffer overflows