[44] | 1 | <?php
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| 2 | //////////////////////////////////////////////////////////////
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| 3 | //// ////
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| 4 | //// p h p U n s h a r p M a s k ////
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| 5 | //// ////
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| 6 | //// Unsharp mask algorithm by Torstein Hønsi 2003. ////
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| 7 | //// thoensi_at_netcom_dot_no ////
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| 8 | //// Please leave this notice. ////
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| 9 | //// ////
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| 10 | //////////////////////////////////////////////////////////////
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| 11 | /// From: http://vikjavev.no/hovudsida/umtestside.php //
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| 12 | // //
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| 13 | // Reformatted by James Heinrich <info@silisoftware.com> //
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| 14 | // for use in phpThumb() on 3 February 2003. //
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| 15 | // //
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| 16 | // phpThumb() is found at http://phpthumb.sourceforge.net ///
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| 17 | //////////////////////////////////////////////////////////////
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| 18 |
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| 19 | /*
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| 20 | WARNING! Due to a known bug in PHP 4.3.2 this script is not working well in this version.
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| 21 | The sharpened images get too dark. The bug is fixed in version 4.3.3.
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| 22 |
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| 23 | Unsharp masking is a traditional darkroom technique that has proven very suitable for
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| 24 | digital imaging. The principle of unsharp masking is to create a blurred copy of the image
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| 25 | and compare it to the underlying original. The difference in colour values
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| 26 | between the two images is greatest for the pixels near sharp edges. When this
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| 27 | difference is subtracted from the original image, the edges will be
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| 28 | accentuated.
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| 29 |
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| 30 | The Amount parameter simply says how much of the effect you want. 100 is 'normal'.
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| 31 | Radius is the radius of the blurring circle of the mask. 'Threshold' is the least
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| 32 | difference in colour values that is allowed between the original and the mask. In practice
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| 33 | this means that low-contrast areas of the picture are left unrendered whereas edges
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| 34 | are treated normally. This is good for pictures of e.g. skin or blue skies.
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| 35 |
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| 36 | Any suggenstions for improvement of the algorithm, expecially regarding the speed
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| 37 | and the roundoff errors in the Gaussian blur process, are welcome.
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| 38 | */
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| 39 |
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| 40 | class phpUnsharpMask {
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| 41 |
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| 42 | function applyUnsharpMask(&$img, $amount, $radius, $threshold) {
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| 43 |
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| 44 | // $img is an image that is already created within php using
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| 45 | // imgcreatetruecolor. No url! $img must be a truecolor image.
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| 46 |
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| 47 | // Attempt to calibrate the parameters to Photoshop:
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| 48 | $amount = min($amount, 500);
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| 49 | $amount = $amount * 0.016;
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| 50 | if ($amount == 0) {
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| 51 | return true;
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| 52 | }
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| 53 |
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| 54 | $radius = min($radius, 50);
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| 55 | $radius = $radius * 2;
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| 56 |
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| 57 | $threshold = min($threshold, 255);
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| 58 |
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| 59 | $radius = abs(round($radius)); // Only integers make sense.
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| 60 | if ($radius == 0) {
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| 61 | return true;
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| 62 | }
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| 63 |
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| 64 | $w = ImageSX($img);
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| 65 | $h = ImageSY($img);
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| 66 | $imgCanvas = ImageCreateTrueColor($w, $h);
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| 67 | $imgCanvas2 = ImageCreateTrueColor($w, $h);
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| 68 | ImageCopy($imgCanvas, $img, 0, 0, 0, 0, $w, $h);
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| 69 | ImageCopy($imgCanvas2, $img, 0, 0, 0, 0, $w, $h);
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| 70 |
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| 71 |
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| 72 | $builtinFilterSucceeded = false;
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| 73 | if ($radius == 1) {
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| 74 | if (phpthumb_functions::version_compare_replacement(phpversion(), '5.0.0', '>=') && phpthumb_functions::gd_is_bundled()) {
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| 75 | if (ImageFilter($imgCanvas, IMG_FILTER_GAUSSIAN_BLUR) && ImageFilter($imgCanvas2, IMG_FILTER_GAUSSIAN_BLUR)) {
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| 76 | $builtinFilterSucceeded = true;
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| 77 | }
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| 78 | }
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| 79 | }
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| 80 |
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| 81 | if (!$builtinFilterSucceeded) {
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| 82 | $imgBlur = ImageCreateTrueColor($w, $h);
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| 83 | $imgBlur2 = ImageCreateTrueColor($w, $h);
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| 84 |
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| 85 | ///////////////////////////
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| 86 | //
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| 87 | // Gaussian blur matrix:
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| 88 | // 1 2 1
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| 89 | // 2 4 2
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| 90 | // 1 2 1
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| 91 | //
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| 92 | ///////////////////////////
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| 93 |
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| 94 | // Move copies of the image around one pixel at the time and merge them with weight
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| 95 | // according to the matrix. The same matrix is simply repeated for higher radii.
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| 96 | for ($i = 0; $i < $radius; $i++) {
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| 97 | ImageCopy ($imgBlur, $imgCanvas, 0, 0, 1, 1, $w - 1, $h - 1); // up left
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| 98 | ImageCopyMerge($imgBlur, $imgCanvas, 1, 1, 0, 0, $w, $h, 50); // down right
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| 99 | ImageCopyMerge($imgBlur, $imgCanvas, 0, 1, 1, 0, $w - 1, $h, 33.33333); // down left
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| 100 | ImageCopyMerge($imgBlur, $imgCanvas, 1, 0, 0, 1, $w, $h - 1, 25); // up right
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| 101 | ImageCopyMerge($imgBlur, $imgCanvas, 0, 0, 1, 0, $w - 1, $h, 33.33333); // left
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| 102 | ImageCopyMerge($imgBlur, $imgCanvas, 1, 0, 0, 0, $w, $h, 25); // right
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| 103 | ImageCopyMerge($imgBlur, $imgCanvas, 0, 0, 0, 1, $w, $h - 1, 20 ); // up
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| 104 | ImageCopyMerge($imgBlur, $imgCanvas, 0, 1, 0, 0, $w, $h, 16.666667); // down
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| 105 | ImageCopyMerge($imgBlur, $imgCanvas, 0, 0, 0, 0, $w, $h, 50); // center
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| 106 | ImageCopy ($imgCanvas, $imgBlur, 0, 0, 0, 0, $w, $h);
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| 107 |
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| 108 | // During the loop above the blurred copy darkens, possibly due to a roundoff
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| 109 | // error. Therefore the sharp picture has to go through the same loop to
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| 110 | // produce a similar image for comparison. This is not a good thing, as processing
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| 111 | // time increases heavily.
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| 112 | ImageCopy ($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h);
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| 113 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 50);
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| 114 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 33.33333);
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| 115 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 25);
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| 116 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 33.33333);
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| 117 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 25);
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| 118 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 20 );
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| 119 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 16.666667);
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| 120 | ImageCopyMerge($imgBlur2, $imgCanvas2, 0, 0, 0, 0, $w, $h, 50);
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| 121 | ImageCopy ($imgCanvas2, $imgBlur2, 0, 0, 0, 0, $w, $h);
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| 122 | }
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| 123 | ImageDestroy($imgBlur);
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| 124 | ImageDestroy($imgBlur2);
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| 125 | }
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| 126 |
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| 127 | // Calculate the difference between the blurred pixels and the original
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| 128 | // and set the pixels
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| 129 | for ($x = 0; $x < $w; $x++) { // each row
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| 130 | for ($y = 0; $y < $h; $y++) { // each pixel
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| 131 |
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| 132 | $rgbOrig = ImageColorAt($imgCanvas2, $x, $y);
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| 133 | $rOrig = (($rgbOrig >> 16) & 0xFF);
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| 134 | $gOrig = (($rgbOrig >> 8) & 0xFF);
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| 135 | $bOrig = ($rgbOrig & 0xFF);
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| 136 |
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| 137 | $rgbBlur = ImageColorAt($imgCanvas, $x, $y);
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| 138 | $rBlur = (($rgbBlur >> 16) & 0xFF);
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| 139 | $gBlur = (($rgbBlur >> 8) & 0xFF);
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| 140 | $bBlur = ($rgbBlur & 0xFF);
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| 141 |
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| 142 | // When the masked pixels differ less from the original
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| 143 | // than the threshold specifies, they are set to their original value.
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| 144 | $rNew = (abs($rOrig - $rBlur) >= $threshold) ? max(0, min(255, ($amount * ($rOrig - $rBlur)) + $rOrig)) : $rOrig;
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| 145 | $gNew = (abs($gOrig - $gBlur) >= $threshold) ? max(0, min(255, ($amount * ($gOrig - $gBlur)) + $gOrig)) : $gOrig;
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| 146 | $bNew = (abs($bOrig - $bBlur) >= $threshold) ? max(0, min(255, ($amount * ($bOrig - $bBlur)) + $bOrig)) : $bOrig;
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| 147 |
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| 148 | if (($rOrig != $rNew) || ($gOrig != $gNew) || ($bOrig != $bNew)) {
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| 149 | $pixCol = ImageColorAllocate($img, $rNew, $gNew, $bNew);
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| 150 | ImageSetPixel($img, $x, $y, $pixCol);
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| 151 | }
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| 152 | }
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| 153 | }
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| 154 | ImageDestroy($imgCanvas);
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| 155 | ImageDestroy($imgCanvas2);
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| 156 |
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| 157 | return true;
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| 158 | }
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| 159 |
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| 160 | }
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| 161 |
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| 162 | ?> |
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