blurhash

README

go-blurhash

A pure Go implementation of Blurhash. The API is stable, however the hashing function in either direction may not be.

Blurhash is an algorithm written by Dag Ågren for Wolt (woltapp/blurhash) that encodes an image into a short (~20-30 byte) ASCII string. When you decode the string back into an image, you get a gradient of colors that represent the original image. This can be useful for scenarios where you want an image placeholder before loading, or even to censor the contents of an image a la Mastodon.

Under the covers, this library is almost a straight port of the C version, which is known to encode images slightly differently than the TypeScript implementation.

Contributing

Issues, feature requests or improvements welcome!

Licence

This project is licensed under the MIT License.

Documentation

Index

• Variables
• func Components(hash string) (x, y int, err error)
• func Decode(hash string, width, height int, punch int) (image.Image, error)
• func DecodeDraw(dst draw.Image, hash string, punch float64) error
• func Encode(xComponents, yComponents int, img image.Image) (hash string, err error)

Variables

var ErrInvalidComponents = errors.New("blurhash: must have between 1 and 9 components")

ErrInvalidComponents is returned when components passed to Encode are invalid.

var ErrInvalidHash = errors.New("blurhash: invalid hash")

ErrInvalidHash is returned when the library encounters a hash it can't recognise.

Functions

func Components

func Components(hash string) (x, y int, err error)

Components returns the X and Y components of a blurhash.

func Decode

func Decode(hash string, width, height int, punch int) (image.Image, error)

Decode returns an NRGBA image of the given hash with the given size.

func DecodeDraw

func DecodeDraw(dst draw.Image, hash string, punch float64) error

DecodeDraw decodes the given hash into the given image.

func Encode

func Encode(xComponents, yComponents int, img image.Image) (hash string, err error)

Encode returns the blurhash for the given image.