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copied!<p>Here's a little upgrade to this script - I found that if the source image has transparency itself, the mask (using the script above) plots a back pixel instead of the source image's transparent pixel. The below extended script takes source image transparency into consideration, and preserves it.</p> <pre><code>// Load source and mask $source = imagecreatefrompng( '1.png' ); $mask = imagecreatefrompng( '2.png' ); // Apply mask to source imagealphamask( $source, $mask ); // Output header( "Content-type: image/png"); imagepng( $source ); function imagealphamask( &$picture, $mask ) { // Get sizes and set up new picture $xSize = imagesx( $picture ); $ySize = imagesy( $picture ); $newPicture = imagecreatetruecolor( $xSize, $ySize ); imagesavealpha( $newPicture, true ); imagefill( $newPicture, 0, 0, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) ); // Resize mask if necessary if( $xSize != imagesx( $mask ) || $ySize != imagesy( $mask ) ) { $tempPic = imagecreatetruecolor( $xSize, $ySize ); imagecopyresampled( $tempPic, $mask, 0, 0, 0, 0, $xSize, $ySize, imagesx( $mask ), imagesy( $mask ) ); imagedestroy( $mask ); $mask = $tempPic; } // Perform pixel-based alpha map application for( $x = 0; $x < $xSize; $x++ ) { for( $y = 0; $y < $ySize; $y++ ) { $alpha = imagecolorsforindex( $mask, imagecolorat( $mask, $x, $y ) ); if(($alpha['red'] == 0) && ($alpha['green'] == 0) && ($alpha['blue'] == 0) && ($alpha['alpha'] == 0)) { // It's a black part of the mask imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) ); // Stick a black, but totally transparent, pixel in. } else { // Check the alpha state of the corresponding pixel of the image we're dealing with. $alphaSource = imagecolorsforindex( $source, imagecolorat( $source, $x, $y ) ); if(($alphaSource['alpha'] == 127)) { imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) ); // Stick a black, but totally transparent, pixel in. } else { $color = imagecolorsforindex( $source, imagecolorat( $source, $x, $y ) ); imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, $color[ 'red' ], $color[ 'green' ], $color[ 'blue' ], $color['alpha'] ) ); // Stick the pixel from the source image in } } } } // Copy back to original picture imagedestroy( $picture ); $picture = $newPicture; } </code></pre>

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