Struct SixelEncoder 

pub struct SixelEncoder {
    pub algorithm: PaletteBuilder,
    pub dither: Dither,
}

The main type for performing sixel encoding.

Combines a PaletteBuilder to generate a color palette from the input image (sixel only supports up to 256 colors) with a Dither algorithm to apply dithering to the reduced color image before encoding it into sixel format.

Choosing a PaletteBuilder

• PaletteBuilder::BitMergeBest or PaletteBuilder::KMeans are good default choices for minimizing the error across the image.
• PaletteBuilder::Focal is a good choice if the image has highlights and other details that other encoders might squash, but is experimental. It is a weighted k-means implementation. Depending on the image, KMeans may be able to capture these highlights already, but it’s worth trying if you’re trying to preserve specific image characteristics.

Choosing a Dither

• Dither::Sierra is a good default choice for dithering, as it produces high-quality results with minimal artifacts.
• Dither::None can be used if performance is a concern.

Fields

algorithm: PaletteBuilder

The color quantization algorithm used to reduce the image to a palette.

dither: Dither

The dithering algorithm applied after quantization.

Implementations

impl SixelEncoder

pub fn new(algorithm: PaletteBuilder, dither: Dither) -> Self

Create a new encoder with the given palette-building algorithm and dithering mode.

pub fn encode(&self, rgba: RgbaImage) -> String

Encode an RGBA image into sixel format with the default palette size of 256 colors.

This is a convenience method that calls encode_with_palette_size with a palette size of 256.

Arguments

• rgba - An RGBA image to encode. The alpha channel is used for transparency handling.

Returns

A String containing the sixel-encoded image data, ready to be printed to a sixel-capable terminal.

Transparency Handling

• Fully transparent pixels (alpha = 0): Encoded as transparent sixel pixels
• Partially transparent pixels: If the partial-transparency feature is enabled, these are blended with the detected terminal background color. Otherwise, treated as opaque.
• Opaque pixels (alpha = 255): Encoded normally

pub fn encode_with_palette_size( &self, image: RgbaImage, palette_size: usize, ) -> String

Encode an RGBA image into sixel format with a custom palette size.

This method provides full control over the color quantization process by allowing you to specify the exact number of colors in the resulting palette. The palette size directly affects both the quality and size of the output.

Arguments

• rgba - An RGBA image to encode. The alpha channel is used for transparency handling.
• palette_size - The number of colors to use in the palette. Valid range is 1-256. Will be automatically clamped if the image has fewer unique colors.

Returns

A String containing the sixel-encoded image data, ready to be printed to a sixel-capable terminal.

Transparency Handling

Same as encode - see that method’s documentation for details.

Trait Implementations

impl Clone for SixelEncoder

fn clone(&self) -> SixelEncoder

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SixelEncoder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SixelEncoder

fn default() -> Self

Returns the “default value” for a type.

impl Copy for SixelEncoder