generating thumbnails

[RobertP]

i have a few questions about generating thumbnails.

 

1. is it best to retain image quality/resolution by using a ratio for shrinking the width/height? example below

2. once i generate a thumbnail, does it make sense to store it on the server for access later?

 

ratio example

	public static function generateThumbnail($file){
	$w = 80;//80px width, height is relative
	header('Content-type: image/jpeg');
	list($width,$height) = getimagesize($file);
	$ratio = $w/$width;
	$new_height = $height*$ratio;
	$image_p = imagecreatetruecolor($w,$new_height);
	$image = imagecreatefromjpeg($file);
	imagecopyresampled($image_p,$image,0,0,0,0,$w,$new_height,$width,$height);
	imagejpeg($image_p,null,100);
}

 

also, i store all my files outside of the web root, and access each one via a php script for downloading / viewing. i do this for security. some files are not blocked to normal members, and others blocked to guests. is this the best way for that?

[scootstah]

1. Usually it's best to either crop or resize while maintaining aspect ratios. Otherwise, it's just going to look bad if you do a substantial resize.

 

2. Yes, it makes sense to store it on the server because generally image manipulations are costly. The less you need to do them the better.

[RobertP]

thank you very much for your relpy.