A function that returns the height or width of an image so that it is optimized for a bounding box set to overflow:hidden. The images will keep their aspect ratio and fit the box.

smartCrop.php

function smartCrop($height,$width,$endHeight,$endWidth){
  $heightWidth='';
	
	if($height <= $endHeight || $width <= $endWidth){
		$height = round($endWidth*$height/$width);
		if($height < $endHeight){
			$width = round($endHeight*$width/$height);
			$heightWidth = "width:".$width."px";
		}
		else{
			$heightWidth = "height:".$height."px";
		}
	}
	
	return $heightWidth;
}