phpUnsharpMask::applyUnsharpMask()

Complexity

Conditions	15
Paths	43

Size

Total Lines	100
Code Lines	57

Duplication

Lines	0
Ratio	0 %

Importance

Changes	4
Bugs	0	Features	0

<?php
    public static function applyUnsharpMask(&$img, $amount, $radius, $threshold)
    {
        // $img is an image that is already created within php using
        // imgcreatetruecolor. No url! $img must be a truecolor image.

        // Attempt to calibrate the parameters to Photoshop:
        $amount    = min($amount, 500) * 0.016;
        $radius    = abs(round(min(50, $radius) * 2)); // Only integers make sense.
        $threshold = min(255, $threshold);
        if ($radius == 0) {
            return true;
        }
        $w         = imagesx($img);
        $h         = imagesy($img);
        $imgCanvas = imagecreatetruecolor($w, $h);
        $imgBlur   = imagecreatetruecolor($w, $h);

        // Gaussian blur matrix:
        //
        //    1    2    1
        //    2    4    2
        //    1    2    1
        //
        //////////////////////////////////////////////////

        if (function_exists('imageconvolution')) { // PHP >= 5.1
            $matrix = [
                [1, 2, 1],
                [2, 4, 2],
                [1, 2, 1],
            ];
            imagecopy($imgBlur, $img, 0, 0, 0, 0, $w, $h);
            imageconvolution($imgBlur, $matrix, 16, 0);
        } else {
            // Move copies of the image around one pixel at the time and merge them with weight
            // according to the matrix. The same matrix is simply repeated for higher radii.
            for ($i = 0; $i < $radius; $i++) {
                imagecopy($imgBlur, $img, 0, 0, 1, 0, $w - 1, $h);               // left
                imagecopymerge($imgBlur, $img, 1, 0, 0, 0, $w, $h, 50);       // right
                imagecopymerge($imgBlur, $img, 0, 0, 0, 0, $w, $h, 50);       // center
                imagecopy($imgCanvas, $imgBlur, 0, 0, 0, 0, $w, $h);
                imagecopymerge($imgBlur, $imgCanvas, 0, 0, 0, 1, $w, $h - 1, 33.33333); // up

33.33333 of type double is incompatible with the type integer expected by parameter $pct of imagecopymerge().

                imagecopymerge($imgBlur, $imgCanvas, 0, 1, 0, 0, $w, $h, 25);       // down
            }
        }

        if ($threshold > 0) {
            // Calculate the difference between the blurred pixels and the original
            // and set the pixels
            for ($x = 0; $x < $w - 1; $x++) { // each row
                for ($y = 0; $y < $h; $y++) { // each pixel

                    $rgbOrig = imagecolorat($img, $x, $y);
                    $rOrig   = (($rgbOrig >> 16) & 0xFF);
                    $gOrig   = (($rgbOrig >> 8) & 0xFF);
                    $bOrig   = ($rgbOrig & 0xFF);

                    $rgbBlur = imagecolorat($imgBlur, $x, $y);

                    $rBlur = (($rgbBlur >> 16) & 0xFF);
                    $gBlur = (($rgbBlur >> 8) & 0xFF);
                    $bBlur = ($rgbBlur & 0xFF);

                    // When the masked pixels differ less from the original
                    // than the threshold specifies, they are set to their original value.
                    $rNew = ((abs($rOrig - $rBlur) >= $threshold) ? max(0, min(255, ($amount * ($rOrig - $rBlur)) + $rOrig)) : $rOrig);
                    $gNew = ((abs($gOrig - $gBlur) >= $threshold) ? max(0, min(255, ($amount * ($gOrig - $gBlur)) + $gOrig)) : $gOrig);
                    $bNew = ((abs($bOrig - $bBlur) >= $threshold) ? max(0, min(255, ($amount * ($bOrig - $bBlur)) + $bOrig)) : $bOrig);

                    if (($rOrig != $rNew) || ($gOrig != $gNew) || ($bOrig != $bNew)) {
                        $pixCol = imagecolorallocate($img, $rNew, $gNew, $bNew);
                        imagesetpixel($img, $x, $y, $pixCol);
                    }
                }
            }
        } else {
            for ($x = 0; $x < $w; $x++) { // each row
                for ($y = 0; $y < $h; $y++) { // each pixel
                    $rgbOrig = imagecolorat($img, $x, $y);
                    $rOrig   = (($rgbOrig >> 16) & 0xFF);
                    $gOrig   = (($rgbOrig >> 8) & 0xFF);
                    $bOrig   = ($rgbOrig & 0xFF);

                    $rgbBlur = imagecolorat($imgBlur, $x, $y);

                    $rBlur = (($rgbBlur >> 16) & 0xFF);
                    $gBlur = (($rgbBlur >> 8) & 0xFF);
                    $bBlur = ($rgbBlur & 0xFF);

                    $rNew   = min(255, max(0, ($amount * ($rOrig - $rBlur)) + $rOrig));
                    $gNew   = min(255, max(0, ($amount * ($gOrig - $gBlur)) + $gOrig));
                    $bNew   = min(255, max(0, ($amount * ($bOrig - $bBlur)) + $bOrig));
                    $rgbNew = ($rNew << 16) + ($gNew << 8) + $bNew;
                    imagesetpixel($img, $x, $y, $rgbNew);
                }
            }
        }
        imagedestroy($imgCanvas);
        imagedestroy($imgBlur);
        return true;
    }