CreateThumbnail is a powerful and customizable class for PHP 5 to create thumbnail images at 72 dpi.
Generated thumbnail (output file) will replace any existing file with the same output file name.

$data = new CreateThumbnail();
$data->setWidth($outputWidth)->setHeight($outputHeight); // output size in pixels
try {
	$data->open($sourceFile); // $sourceFile as string
	$data->process($outputFile); // $outputFile as string
}catch (Exception $e){
	echo $e->getCode()." - ".$e->getMessage();
}

$data = new CreateThumbnail();
$data->setWidth($pixels);
$data->setWidth($outputWidth); // in pixels
$data->setHeight($outputHeight); // in pixels
// $data->setPrefix($outputPrefixName); // suffix for output file name (string)
// $data->setSuffix($outputSuffixName); // prefix for output file name (string)
$data->setQuality($qualityCoeff); // integer from 1 to 100
$data->setSharpen($sharpenStyle); // "none" or "soft" or "medium" or "hard"
$data->setBrightness(brightnessCoeff); // integer from -10 to 10
// $data->setAlt("My image");

$sourceFile = "myFolder/myImage.jpg";
$outputFile = "myOutputFolder/thumb"; // if not specified, output file is created in the source folder

try {
	$data->open($sourceFile);
	// ----- image opening OK : go on
	try {
		$data->process($outputFile);
		echo '<img src="'.$data->getName().'" width="'.$data->getWidth().'" 
height="'.$data->getHeight().'" alt="'.$data->getAlt().'" />';
	}catch (Exception $e){
		echo $e->getCode().' - '.$e->getMessage();
	}
}catch (Exception $e){
	echo $e->getCode().' - '.$e->getMessage();
}

echo "OPEN LOG:".print_r($data->getLog("open"), 1);
echo "PROCESS LOG:".print_r($data->getLog("process"), 1);