diff --git a/app/Util/Blurhash/AC.php b/app/Util/Blurhash/AC.php new file mode 100644 index 000000000..a157c48b8 --- /dev/null +++ b/app/Util/Blurhash/AC.php @@ -0,0 +1,34 @@ + 0; + return $sign * pow(abs($base), $exp); + } +} \ No newline at end of file diff --git a/app/Util/Blurhash/Base83.php b/app/Util/Blurhash/Base83.php new file mode 100644 index 000000000..043ca2e60 --- /dev/null +++ b/app/Util/Blurhash/Base83.php @@ -0,0 +1,39 @@ + 9) || ($components_y < 1 || $components_y > 9)) { + throw new InvalidArgumentException("x and y component counts must be between 1 and 9 inclusive."); + } + $height = count($image); + $width = count($image[0]); + + $image_linear = $image; + if (!$linear) { + $image_linear = []; + for ($y = 0; $y < $height; $y++) { + $line = []; + for ($x = 0; $x < $width; $x++) { + $pixel = $image[$y][$x]; + $line[] = [ + Color::toLinear($pixel[0]), + Color::toLinear($pixel[1]), + Color::toLinear($pixel[2]) + ]; + } + $image_linear[] = $line; + } + } + + $components = []; + $scale = 1 / ($width * $height); + for ($y = 0; $y < $components_y; $y++) { + for ($x = 0; $x < $components_x; $x++) { + $normalisation = $x == 0 && $y == 0 ? 1 : 2; + $r = $g = $b = 0; + for ($i = 0; $i < $width; $i++) { + for ($j = 0; $j < $height; $j++) { + $color = $image_linear[$j][$i]; + $basis = $normalisation + * cos(M_PI * $i * $x / $width) + * cos(M_PI * $j * $y / $height); + + $r += $basis * $color[0]; + $g += $basis * $color[1]; + $b += $basis * $color[2]; + } + } + + $components[] = [ + $r * $scale, + $g * $scale, + $b * $scale + ]; + } + } + + $dc_value = DC::encode(array_shift($components) ?: []); + + $max_ac_component = 0; + foreach ($components as $component) { + $component[] = $max_ac_component; + $max_ac_component = max ($component); + } + + $quant_max_ac_component = (int) max(0, min(82, floor($max_ac_component * 166 - 0.5))); + $ac_component_norm_factor = ($quant_max_ac_component + 1) / 166; + + $ac_values = []; + foreach ($components as $component) { + $ac_values[] = AC::encode($component, $ac_component_norm_factor); + } + + $blurhash = Base83::encode($components_x - 1 + ($components_y - 1) * 9, 1); + $blurhash .= Base83::encode($quant_max_ac_component, 1); + $blurhash .= Base83::encode($dc_value, 4); + foreach ($ac_values as $ac_value) { + $blurhash .= Base83::encode((int) $ac_value, 2); + } + + return $blurhash; + } + + public static function decode (string $blurhash, int $width, int $height, float $punch = 1.0, bool $linear = false): array { + if (empty($blurhash) || strlen($blurhash) < 6) { + throw new InvalidArgumentException("Blurhash string must be at least 6 characters"); + } + + $size_info = Base83::decode($blurhash[0]); + $size_y = floor($size_info / 9) + 1; + $size_x = ($size_info % 9) + 1; + + $length = (int) strlen($blurhash); + $expected_length = (int) (4 + (2 * $size_y * $size_x)); + if ($length !== $expected_length) { + throw new InvalidArgumentException("Blurhash length mismatch: length is {$length} but it should be {$expected_length}"); + } + + $colors = [DC::decode(Base83::decode(substr($blurhash, 2, 4)))]; + + $quant_max_ac_component = Base83::decode($blurhash[1]); + $max_value = ($quant_max_ac_component + 1) / 166; + for ($i = 1; $i < $size_x * $size_y; $i++) { + $value = Base83::decode(substr($blurhash, 4 + $i * 2, 2)); + $colors[$i] = AC::decode($value, $max_value * $punch); + } + + $pixels = []; + for ($y = 0; $y < $height; $y++) { + $row = []; + for ($x = 0; $x < $width; $x++) { + $r = $g = $b = 0; + for ($j = 0; $j < $size_y; $j++) { + for ($i = 0; $i < $size_x; $i++) { + $color = $colors[$i + $j * $size_x]; + $basis = + cos((M_PI * $x * $i) / $width) * + cos((M_PI * $y * $j) / $height); + + $r += $color[0] * $basis; + $g += $color[1] * $basis; + $b += $color[2] * $basis; + } + } + + $row[] = $linear ? [$r, $g, $b] : [ + Color::toSRGB($r), + Color::toSRGB($g), + Color::toSRGB($b) + ]; + } + $pixels[] = $row; + } + + return $pixels; + } +} \ No newline at end of file diff --git a/app/Util/Blurhash/Color.php b/app/Util/Blurhash/Color.php new file mode 100644 index 000000000..4b64c32f7 --- /dev/null +++ b/app/Util/Blurhash/Color.php @@ -0,0 +1,19 @@ +> 16; + $g = ($value >> 8) & 255; + $b = $value & 255; + return [ + Color::toLinear($r), + Color::toLinear($g), + Color::toLinear($b) + ]; + } +} \ No newline at end of file