The Basics of GD: The GD Library is usually bundled with PHP, and is used to manipulate graphics with code. You can start by creating graphics that simply consist of text. Later, you can move on to actually drawing the images yourself with the code. You can even use these basics of drawing to create charts and graphs with your website data.
Thumbnailing: When you let a user (or yourself) upload pictures, it is useful to be able to resize them to fit in the appropriate space. You can dynamically create thumbnails from other GD images you have drawn, or from other photos or graphics on your server using the GD library.
Rotating: Another useful way to manipulate an image is to rotate it. Often we turn the camera to get a better photo, but then end up with a digital picture on it's side. Fortunately, you can rotate images using the GD Library.
Greyscale and Tones: You can also change the tones of a photo or graphic you are working with in GD. We used the GD library to turn a color photo into a grayscale photo.
