Photography > Optimizing Files

The World Wide Web supports two types of image file formats, JPEG and GIF. First off, we'll learn a bit about these formats. Then we'll learn which type of format to use based on image content and purpose.

For JPEGs, we'll start with a few uncompressed images and subject them to greater and greater compression. We'll see what happens to the images themselves, as well as monitor the effect on filesize. We'll look at the data and the images in side-by-side comparisons, and evaluate of the results of the image compression.

For GIFs, we'll discuss color-depth and its effect on filesize and image quality. We'll use examples and examine file data at each turn. Then, we'll discuss some of the unique features of the GIF format which have become a necessity on the Web, including interlacing, transparency and animation.

JPEG is usually best for images that involve smooth color gradients; typical examples are photos and naturalistic artwork.

GIF is usually best for images with sharp-edged areas of flat color. Examples include line drawings, simple icons and buttons, and textual images