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// $Id: imagefilter.inc,v 1.3.4.1 2009/03/18 08:35:59 drewish Exp $
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//Made by Chao Xu(Mgccl) 3/1/07
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// Drupal code style and some restructuring by dopry. http://www.darrelopry.com
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define('IMG_FILTER_NEGATE', 0);
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define('IMG_FILTER_GRAYSCALE', 1);
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define('IMG_FILTER_BRIGHTNESS', 2);
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define('IMG_FILTER_CONTRAST', 3);
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define('IMG_FILTER_COLORIZE', 4);
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define('IMG_FILTER_EDGEDETECT', 5);
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define('IMG_FILTER_EMBOSS', 6);
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define('IMG_FILTER_GAUSSIAN_BLUR', 7);
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define('IMG_FILTER_SELECTIVE_BLUR', 8);
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define('IMG_FILTER_MEAN_REMOVAL', 9);
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define('IMG_FILTER_SMOOTH', 10);
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define('IMAGEAPI_IMAGEFILTER_PHP', 1);
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* walk each pixel in an image applying $callback to it.
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function _imageapi_gd_pixel_color_walk(&$im, $callback, $arg1 = NULL, $arg2 = NULL, $arg3 = NULL, $arg4 = NULL) {
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$max_y = imagesy($im);
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$max_x = imagesx($im);
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for ($y=0; $y < $max_y; ++$y) {
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for ($x=0; $x < $max_x; ++$x) {
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$rgb = imagecolorat($im, $x, $y);
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$r = ($rgb >> 16) & 0xFF;
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$g = ($rgb >> 8) & 0xFF;
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$callback($r, $g, $b, $a, $arg1, $arg2, $arg3, $arg4);
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// sanitize rgb values.
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$r = ($r > 255)? 255 : (($r < 0)? 0:$r);
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$g = ($g > 255)? 255 : (($g < 0)? 0:$g);
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$b = ($b > 255)? 255 : (($b < 0)? 0:$b);
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$a = ($a > 127)? 127 : (($a < 0)? 0:$a);
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if (!$color = imagecolorallocatealpha($im, $r, $g, $b, $a)) {
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$color = imagecolorclosestalpha($im, $r, $g, $b, $a);
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imagesetpixel($im, $x, $y, $color);
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function _imageapi_gd_pixel_negate(&$r, &$g, &$b, &$a) {
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function _imageapi_gd_pixel_grayscale(&$r, &$g, &$b, &$a) {
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$r = round($r * 0.299 + $g * 0.587 + $b * 0.114);
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function _imageapi_gd_pixel_brightness(&$r, &$g, &$b, &$a, $arg1) {
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function _imageapi_gd_pixel_contrast(&$r, &$g, &$b, &$a, $contrast) {
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// normalize color value between -0.5 - 0.5
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// multiply by contrast value to accentuate positive/negative value.
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// denormalize to 0-255 range.
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$r = ((($r/255 - 0.5) * $contrast) + 0.5) * 255;
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$g = ((($g/255 - 0.5) * $contrast) + 0.5) * 255;
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$b = ((($b/255 - 0.5) * $contrast) + 0.5) * 255;
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function _imageapi_gd_pixel_colorize(&$r, &$g, &$b, &$a, $arg1, $arg2, $arg3, $arg4) {
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function imagefilter(&$im, $var, $arg1 = NULL, $arg2 = NULL, $arg3 = NULL, $arg4 = NULL) {
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case IMG_FILTER_NEGATE:
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_imageapi_gd_pixel_color_walk($im, '_imageapi_gd_pixel_negate');
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case IMG_FILTER_GRAYSCALE:
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_imageapi_gd_pixel_color_walk($im, '_imageapi_gd_pixel_grayscale');
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case IMG_FILTER_BRIGHTNESS:
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_imageapi_gd_pixel_color_walk($im, '_imageapi_gd_pixel_brightness', $arg1);
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case IMG_FILTER_CONTRAST:
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// normalize between 0-1, square to keep positive.
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$contrast = pow((100-$arg1)/100, 2);
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_imageapi_gd_pixel_color_walk($im, '_imageapi_gd_pixel_contrast', $contrast);
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case IMG_FILTER_COLORIZE:
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$arg1 = (is_null($arg1)) ? 0 : $arg1;
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$arg2 = (is_null($arg2)) ? 0 : $arg2;
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$arg3 = (is_null($arg3)) ? 0 : $arg3;
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$arg4 = (is_null($arg4)) ? 0 : $arg4;
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_imageapi_gd_pixel_color_walk($im, '_imageapi_gd_pixel_colorize', $arg1, $arg2, $arg3, $arg4);
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case IMG_FILTER_EDGEDETECT:
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return imageconvolution($im, array(array(-1, 0, -1), array(0, 4, 0), array(-1, 0, -1)), 1, 127);
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case IMG_FILTER_EMBOSS:
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return imageconvolution($im, array(array(1.5, 0, 0), array(0, 0, 0), array(0, 0, -1.5)), 1, 127);
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case IMG_FILTER_GAUSSIAN_BLUR:
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return imageconvolution($im, array(array(1, 2, 1), array(2, 4, 2), array(1, 2, 1)), 16, 0);
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case IMG_FILTER_SELECTIVE_BLUR:
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for ($y = 0; $y<$max_y; ++$y) {
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for ($x = 0; $x<$max_x; ++$x) {
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$flt_r_sum = $flt_g_sum = $flt_b_sum = 0;
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$cpxl = imagecolorat($im, $x, $y);
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for ($j=0; $j<3; ++$j) {
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for ($i=0; $i<3; ++$i) {
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if (($j == 1) && ($i == 1)) {
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$flt_r[1][1] = $flt_g[1][1] = $flt_b[1][1] = 0.5;
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$pxl = imagecolorat($im, $x-(3>>1)+$i, $y-(3>>1)+$j);
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//$r = (($pxl >> 16) & 0xFF);
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//$g = (($pxl >> 8) & 0xFF);
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//$b = ($pxl & 0xFF);
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$new_r = abs((($cpxl >> 16) & 0xFF) - (($pxl >> 16) & 0xFF));
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$flt_r[$j][$i] = 1/$new_r;
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$new_g = abs((($cpxl >> 8) & 0xFF) - (($pxl >> 8) & 0xFF));
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$flt_g[$j][$i] = 1/$new_g;
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$new_b = abs(($cpxl & 0xFF) - ($pxl & 0xFF));
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$flt_b[$j][$i] = 1/$new_b;
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$flt_r_sum += $flt_r[$j][$i];
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$flt_g_sum += $flt_g[$j][$i];
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$flt_b_sum += $flt_b[$j][$i];
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for ($j=0; $j<3; ++$j) {
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for ($i=0; $i<3; ++$i) {
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if ($flt_r_sum != 0) $flt_r[$j][$i] /= $flt_r_sum;
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if ($flt_g_sum != 0) $flt_g[$j][$i] /= $flt_g_sum;
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if ($flt_b_sum != 0) $flt_b[$j][$i] /= $flt_b_sum;
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$new_r = $new_g = $new_b = 0;
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for ($j=0; $j<3; ++$j) {
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for ($i=0; $i<3; ++$i) {
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$pxl = imagecolorat($im, $x-(3>>1)+$i, $y-(3>>1)+$j);
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$new_r += (($pxl >> 16) & 0xFF) * $flt_r[$j][$i];
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$new_g += (($pxl >> 8) & 0xFF) * $flt_g[$j][$i];
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$new_b += ($pxl & 0xFF) * $flt_b[$j][$i];
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$new_r = ($new_r > 255)? 255 : (($new_r < 0)? 0:$new_r);
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$new_g = ($new_g > 255)? 255 : (($new_g < 0)? 0:$new_g);
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$new_b = ($new_b > 255)? 255 : (($new_b < 0)? 0:$new_b);
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$new_pxl = imagecolorallocatealpha($im, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
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if ($new_pxl == FALSE) {
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$new_pxl = imagecolorclosestalpha($im, (int)$new_r, (int)$new_g, (int)$new_b, $new_a);
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imagesetpixel($im, $x, $y, $new_pxl);
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case IMG_FILTER_MEAN_REMOVAL:
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return imageconvolution($im, array(array(-1, -1, -1), array(-1, 9, -1), array(-1, -1, -1)), 1, 0);
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case IMG_FILTER_SMOOTH:
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return imageconvolution($im, array(array(1, 1, 1), array(1, $arg1, 1), array(1, 1, 1)), $arg1 + 8, 0);