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
$matrix = array(array(1, 2, 1), array(2, 4, 2), array(1, 2, 1));
ImageCopy($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, $h - 1, 33.33333);
// up
ImageCopyMerge($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;
}
/**
* Generates a resized version of an image and saves it in the image cache folder.
*
* @param string $source_file The original image to be resized.
* @param string $cache_file The target file where the resized version will be cached.
* @param int $resolution The resolution breakpoint at which the given image is to be resized.
* @param int $jpg_quality The JPEG quality that will be used for resizing the images.
* @param bool $sharpen Whether to sharpen the resized images or not.
*
* @return array Associative array( bool: success, string: message) with the result of the image cache generation.
*/
function adaptive_images_script_generate_image($source_file, $cache_file, $resolution, $jpg_quality, $sharpen)
{
// Get original image dimensions.
$dimensions = @GetImageSize($source_file);
$width = $dimensions[0];
$height = $dimensions[1];
// Calculate resized image dimensions.
$ratio = $height / $width;
$new_width = $resolution;
$new_height = ceil($new_width * $ratio);
// Start creating the resized image with a blank true color canvas.
$destination = @ImageCreateTrueColor($new_width, $new_height);
$extension = adaptive_images_script_get_file_extension($source_file);
switch ($extension) {
case 'png':
$source = @ImageCreateFromPng($source_file);
break;
case 'gif':
$source = @ImageCreateFromGif($source_file);
break;
default:
$source = @ImageCreateFromJpeg($source_file);
break;
}
// PNG images generation.
if ($extension == 'png') {
// Create a transparent color and fill the blank canvas with it.
$rbga_color = @ImageColorAllocateAlpha($destination, 0, 0, 0, 127);
@ImageColorTransparent($destination, $rbga_color);
@ImageFill($destination, 0, 0, $rbga_color);
// Copy source image to destination image with interpolation.
@ImageCopyResampled($destination, $source, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
// Convert true colour image to pallette image to achieve PNG-8 compression.
$dither = TRUE;
@ImageTrueColorToPalette($destination, $dither, 255);
// Save alpha (transparency) of destination image.
$save_alpha = TRUE;
@ImageSaveAlpha($destination, $save_alpha);
// Disable blending of destination image to allow for alpha (transparency) above.
$enable_alpha_blending = FALSE;
@ImageAlphaBlending($destination, $enable_alpha_blending);
}
// GIF images generation.
if ($extension == 'gif') {
// Create a transparent color and fill the blank canvas with it.
$rbga_color = @ImageColorAllocateAlpha($destination, 0, 0, 0, 127);
@ImageColorTransparent($destination, $rbga_color);
@ImageFill($destination, 0, 0, $rbga_color);
// Copy source image to destination image with interpolation.
@ImageCopyResampled($destination, $source, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
// Convert true colour image to pallette image to achieve PNG8 compression.
$dither = TRUE;
@ImageTrueColorToPalette($destination, $dither, 255);
// Enable alpha blending of destination image.
$enable_alpha_blending = TRUE;
@ImageAlphaBlending($destination, $enable_alpha_blending);
}
// JPEG images generation.
if ($extension == 'jpg' || $extension == 'jpeg') {
// Enable JPEG interlacing.
ImageInterlace($destination, TRUE);
// Interpolates source image to destination image to make it more clear for JPGs.
@ImageCopyResampled($destination, $source, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
}
// Cleanup source image from memory.
@ImageDestroy($source);
// Do sharpening if requested.
if ($sharpen && function_exists('imageconvolution')) {
$sharpness_factor = adaptive_images_script_sharpness_factor($width, $new_width);
$sharpness_transformation_matrix = array(array(-1, -2, -1), array(-2, $sharpness_factor + 12, -2), array(-1, -2, -1));
// OR
// $sharpenMatrix = array
// (
// array(-1.2, -1, -1.2),
// array(-1, 20, -1),
// array(-1.2, -1, -1.2)
// );
// $divisor = array_sum(array_map('array_sum', $sharpenMatrix));
// OR
// $sharpen = array(
// array(0.0, -1.0, 0.0),
// array(-1.0, 5.0, -1.0),
// array(0.0, -1.0, 0.0)
// );
// $divisor = array_sum(array_map('array_sum', $sharpen));
// OR
// $matrix = array(
// array(-1, -1, -1),
// array(-1, 16, -1),
// array(-1, -1, -1),
// );
// $divisor = array_sum(array_map('array_sum', $matrix));
@ImageConvolution($destination, $sharpness_transformation_matrix, $sharpness_factor, 0);
}
// Check and ensure that cache directory is setup OK.
$cache_path = dirname($cache_file);
if (!adaptive_images_script_ensure_cache_directory_ready($cache_path)) {
return array('success' => false, 'message' => 'Cache directory for image not accessible or writeable.');
}
// Save resized image in cache.
switch ($extension) {
case 'png':
$png_compression_level = 6;
$image_saved = @ImagePng($destination, $cache_file, $png_compression_level, PNG_FILTER_NONE);
break;
case 'gif':
$image_saved = @ImageGif($destination, $cache_file);
break;
default:
$image_saved = @ImageJpeg($destination, $cache_file, $jpg_quality);
break;
}
// Cleanup destination image from memory.
@ImageDestroy($destination);
// Check if all OK.
if (!$image_saved && !file_exists($cache_file)) {
return array('success' => false, 'message' => 'Resized image could not be created.');
}
// Return file of resized and cached image.
return array('success' => true, 'message' => $cache_file);
}