Chapter 8. Generating Thumbnail Images
PHP has an extensive range of functions designed to work with images. You've already met one of them,
getimagesize(), in Chapter 4. As well as providing useful information about an image's dimensions, PHP can manipulate images by resizing or rotating them. It can also add text dynamically without affecting the original; it can even create images on the fly.
To give you just a taste of PHP image manipulation, I'm going to show you how to generate a smaller copy of an uploaded image. Most of the time, you'll want to use a dedicated graphics program, such as Photoshop or Fireworks, to generate thumbnail images ...