Pure PHP implementation of Blurhash

v1.2.1 2021-01-18 11:17 UTC

This package is auto-updated.

Last update: 2021-11-08 15:49:58 UTC


A pure PHP 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.


$ composer require kornrunner/blurhash


Encoding an image to blurhash expects two-dimensional array of colors of image pixels, sample code:


require_once 'vendor/autoload.php';

use kornrunner\Blurhash\Blurhash;

$file  = 'test/data/img1.jpg';
$image = imagecreatefromstring(file_get_contents($file));
$width = imagesx($image);
$height = imagesy($image);

$pixels = [];
for ($y = 0; $y < $height; ++$y) {
    $row = [];
    for ($x = 0; $x < $width; ++$x) {
        $index = imagecolorat($image, $x, $y);
        $colors = imagecolorsforindex($image, $index);

        $row[] = [$colors['red'], $colors['green'], $colors['blue']];
    $pixels[] = $row;

$components_x = 4;
$components_y = 3;
$blurhash = Blurhash::encode($pixels, $components_x, $components_y);
// LEHV9uae2yk8pyo0adR*.7kCMdnj

For decoding of blurhash people will likely go for some other implementation (JavaScript/TypeScript). PHP decoder returns a pixel array that can be used to generate the image:


require_once 'vendor/autoload.php';

use kornrunner\Blurhash\Blurhash;

$blurhash = 'LEHV6nWB2yk8pyo0adR*.7kCMdnj';
$width    = 269;
$height   = 173;

$pixels = Blurhash::decode($blurhash, $width, $height);
$image  = imagecreatetruecolor($width, $height);
for ($y = 0; $y < $height; ++$y) {
    for ($x = 0; $x < $width; ++$x) {
        [$r, $g, $b] = $pixels[$y][$x];
        imagesetpixel($image, $x, $y, imagecolorallocate($image, $r, $g, $b));
imagepng($image, 'blurhash.png');


Issues, feature requests or improvements welcome!


This project is licensed under the MIT License.