Here is another great tutorial from Codrops.Resizing and Cropping Images With Canvas.In this tutorial you will learn how to resize and crop images using JavaScript and the HTML5 Canvas element using controls, commonly seen in photo editing applications.
You do this by creating an HTML5 canvas element and drawing the image to the canvas at a particular size, then extracting the new image data from the canvas as a data URI. Most browsers have good support for these methods, so you can probably use this technique right now, however just be aware of some limitations unrelated to browser support such as quality and performance.
