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https://github.com/buckket/go-blurhash
A Blurhash implementation in pure Go (Decode/Encode)
https://github.com/buckket/go-blurhash
blurhash go golang golang-library mastodon
Last synced: 26 days ago
JSON representation
A Blurhash implementation in pure Go (Decode/Encode)
- Host: GitHub
- URL: https://github.com/buckket/go-blurhash
- Owner: buckket
- License: gpl-3.0
- Created: 2019-05-09T22:14:15.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-01-10T15:58:52.000Z (10 months ago)
- Last Synced: 2024-04-14T01:06:01.392Z (7 months ago)
- Topics: blurhash, go, golang, golang-library, mastodon
- Language: Go
- Size: 160 KB
- Stars: 188
- Watchers: 2
- Forks: 8
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
- go-awesome - go-blurhash - BlurHash, a hash algorithm for blurring images (Open source library / Algorithm)
README
# go-blurhash [](https://travis-ci.org/buckket/go-blurhash) [](https://goreportcard.com/report/github.com/buckket/go-blurhash) [](https://codecov.io/gh/buckket/go-blurhash) [](https://pkg.go.dev/github.com/buckket/go-blurhash)
**go-blurhash** is a pure Go implementation of the [BlurHash](https://github.com/woltapp/blurhash) algorithm, which is used by
[Mastodon](https://github.com/tootsuite/mastodon) an other Fediverse software to implement a swift way of preloading placeholder images as well
as hiding sensitive media. Read more about it [here](https://blog.joinmastodon.org/2019/05/improving-support-for-adult-content-on-mastodon/).
**tl;dr:** BlurHash is a compact representation of a placeholder for an image.
This library allows generating the BlurHash of a given image, as well as
reconstructing a blurred version with specified dimensions from a given BlurHash.
This library is based on the following reference implementations:
- Encoder: [https://github.com/woltapp/blurhash/blob/master/C](https://github.com/woltapp/blurhash/blob/master/C) (C)
- Decoder: [https://github.com/woltapp/blurhash/blob/master/TypeScript](https://github.com/woltapp/blurhash/blob/master/TypeScript) (TypeScript)
BlurHash is written by [Dag Ågren](https://github.com/DagAgren) / [Wolt](https://github.com/woltapp).
| | Before | After |
| ---------- |:------------------------------:| :-----------------------------:|
| **Image** | ![alt text][test] | "LFE.@D9F01_2%L%MIVD*9Goe-;WB" |
| **Hash** | "LFE.@D9F01_2%L%MIVD*9Goe-;WB" | ![alt text][test_blur]
[test]: test.png "Blurhash example input."
[test_blur]: test_blur.png "Blurhash example output"
## Installation
### From source
go get -u github.com/buckket/go-blurhash
## Usage
go-blurhash exports three functions:
```go
func blurhash.Encode(xComponents, yComponents int, rgba image.Image) (string, error)
func blurhash.Decode(hash string, width, height, punch int) (image.Image, error)
func blurhash.Components(hash string) (xComponents, yComponents int, err error)
```
Here’s a simple demonstration. Check [pkg.go.dev](https://pkg.go.dev/github.com/buckket/go-blurhash) for the full documentation.
```go
package main
import (
"fmt"
"github.com/buckket/go-blurhash"
"image/png"
"os"
)
func main() {
// Generate the BlurHash for a given image
imageFile, _ := os.Open("test.png")
loadedImage, err := png.Decode(imageFile)
str, _ := blurhash.Encode(4, 3, loadedImage)
if err != nil {
// Handle errors
}
fmt.Printf("Hash: %s\n", str)
// Generate an image for a given BlurHash
// Width will be 300px and Height will be 500px
// Punch specifies the contrasts and defaults to 1
img, err := blurhash.Decode(str, 300, 500, 1)
if err != nil {
// Handle errors
}
f, _ := os.Create("test_blur.png")
_ = png.Encode(f, img)
// Get the x and y components used for encoding a given BlurHash
x, y, err := blurhash.Components("LFE.@D9F01_2%L%MIVD*9Goe-;WB")
if err != nil {
// Handle errors
}
fmt.Printf("xComponents: %d, yComponents: %d", x, y)
}
```
## Limitations
- Presumably a bit slower than the C implementation (TODO: Benchmarks)
## Notes
- As mentioned [here](https://github.com/woltapp/blurhash#how-fast-is-encoding-decoding), it’s best to
generate very small images (~32x32px) via BlurHash and scale them up to the desired dimensions afterwards for optimal performance.
- Since [#2](https://github.com/buckket/go-blurhash/pull/2) we diverted from the reference implementation by memorizing sRGBtoLinear values, thus increasing encoding speed at the cost of higher memory usage.
- Starting with v1.1.0 the signature of blurhash.Encode() has changed slightly (see [#3](https://github.com/buckket/go-blurhash/issues/3)).
## License
GNU GPLv3+