Today I have new article for PHP. I will tell you about drawing graphs with GD. Plus - we will smooth our graph with curve lines using cubic splines interpolation method. You can read more about method at Wikipedia.

All of the code is included in the post, ready for cop and pasting - the HTML, CSS plus the PHP to generate the graph, plot the points and apply the cubic splines values. You can check out a live demo of it in action or just download the code and get started on your own.

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).