Crate a_sixel

A-Sixel library for encoding sixel images.

Basic Usage

use a_sixel::BitMergeSixelEncoderBest;
use image::RgbImage;

let img = RgbImage::new(100, 100);
println!("{}", <BitMergeSixelEncoderBest>::encode(&img));

Choosing an Encoder

• I want good quality:
  • Use BitMergeSixelEncoderBest or KMeansSixelEncoder.
• I’m time constrained:
  • Use BitMergeSixelEncoderLow, BitSixelEncoder, or OctreeSixelEncoder.
• I’m really time constrained and can sacrifice a little quality:
  • Use BitSixelEncoder<NoDither>.

For a more detailed breakdown, here’s the encoders by average speed and quality against the test images (speed figures will vary) at 256 colors with Sierra dithering:

Algorithm	MSE	DSSIM	Execution Time (ms)	Initial Buckets
adu	15.56	0.0054	1473	N/A
bit	36.42	0.0132	367	N/A
bit-merge-low	12.10	0.0046	559	2^14
bit-merge	10.96	0.0040	1198	2^18
bit-merge-better	10.77	0.0039	2196	2^20
bit-merge-best	10.75	0.0039	2850	2^21
focal	11.72	0.0043	3253	2^21
k-means	10.86	0.0040	6208	N/A
k-medians	18.68	0.0075	10688	N/A
median-cut	20.27	0.0061	627	N/A
octree (max-heap)	66.60	0.0163	589	N/A
octree (min-heap)	332.29	0.0890	552	N/A

Here’s the encoders at 16 colors with Sierra dithering:

Algorithm	MSE	DSSIM	Execution Time (ms)	Initial Buckets
adu	120.45	0.0371	280	N/A
bit	182.07	0.0492	247	N/A
bit-merge	98.10	0.0307	993	2^18
focal	107.17	0.0335	3045	2^21
k-means	97.02	0.0297	664	N/A
k-medians	171.20	0.0486	5792	N/A
median-cut	168.88	0.0381	317	N/A
octree (max-heap)	546.05	0.0922	341	N/A
octree (min-heap)	879.79	0.2536	349	N/A

Re-exports

pub use crate::adu::ADUPaletteBuilder;

pub use crate::bit::BitPaletteBuilder;

pub use crate::bitmerge::BitMergePaletteBuilder;

pub use crate::focal::FocalPaletteBuilder;

pub use crate::kmeans::KMeansPaletteBuilder;

pub use crate::kmedians::KMediansPaletteBuilder;

pub use crate::median_cut::MedianCutPaletteBuilder;

pub use crate::octree::OctreePaletteBuilder;

Modules

adu

Use Adaptive Distributive Units to “learn” the image’s color properties and select palette entries.

bit

Encodes a palette by bucketing bit ranges into a power of two number of buckets. This is very fast and produces ok results for most images at larger palette sizes (e.g. 256).

bitmerge

Uses BitSixelEncoder with k-means and agglomerative merging to build a palette.

dither

A collection of various dithering algorithms that can be used with the SixelEncoder to dither the result.

focal

Use weighted pixels based on the image’s spectral properties to provided weighted input to k-means.

kmeans

Use k-means clustering to determine a palette for the image.

kmedians

Uses k-medians to build a palette of colors.

median_cut

https://en.wikipedia.org/wiki/Median_cut

octree

Uses an octree to build a palette from an image.

Structs

SixelEncoder

The main type for performing sixel encoding.

Traits

PaletteBuilder

A trait for types that perform quantization of an image to a target palette size.

Type Aliases

ADUSixelEncoder

BitMergeSixelEncoder

BitMergeSixelEncoderBest

BitMergeSixelEncoderBetter

BitMergeSixelEncoderLow

BitSixelEncoder

FocalSixelEncoder

KMeansSixelEncoder

KMediansSixelEncoder

MedianCutSixelEncoder

OctreeSixelEncoder