DevShed concludes their series on using the GD graphics libraries in PHP with thie new article focusing on the use of some of the simple filtering functionality the library has to offer.

In this article I'm going to demonstrate how the GD library can be used to apply some basic graphic filters (yes, like Photoshop, but much simpler) by utilizing the versatility of a brand new function called "imagefilter()". As you'll see shortly, with this function it is possible to reverse, blur and highlight the colors of a determined image, as well as convert it to its grayscale version, among other things.

They use the imagefilter function in a few different examples - altering the colors in an image, working with contrast and brightness and various other filters (like smoothing, embossing, blurring and colorizing).