The purpose of this chapter is to put dynamic image generation in perspective and illustrate how HTML tags is used to call image generating scripts. Even if You are familiar with PHP it is strongly recommended to quickly browse through this chapter to make sure all concepts are known.
If You fully understand and can explain the concept of MIME types, HTTP streams and why the "Headers already sent error" error is very common when generating dynamic images with PHP it is probably safe to skip this chapter. Otherwise it might be wise to read through this chapter once.