How to resize an image (on the fly) and keep its aspect ratio using GD
This is a PHP Class useful if you need to resize images keeping their aspect ratio, using the GD Library. The new height is calculated proportionally to the new width’s size and reverse. For instance you have an image with the following dimensions: width – 1000, height – 800. Its thumbnail with a width of 250 will have the height of 200 (the ratio is kept).