Web graphics: Which format is the best?
Drawings, diagrams, and photos can focus your students' attention and explain complicated ideas. Putting those images up on your Web site can be a confusing process, however. Help is on the way!
Web graphics typically come in three varieties: .GIF, .JPG, and .PNG. Your choice of format should depend on the kind of image you're using.Here are the basic differences you'll need to consider.
as this Catalyst
logo, is ideal
for .GIF files.
GIF stands for Graphics Interchange Format, and it is a patented compression format owned by CompuServe and Unisys. It uses a "lossless" form of compression, which means that when you save the image, you don't lose any of the data.
a .GIF looks patchy.
JPEG (or JPG) stands for Joint Photographic Experts Group, named after the standards committee that developed it. Unlike GIF, its compression scheme isn't lossless, but lossy, so it does throw away some of the data.
saved as a .JPG
usually looks clear.
PNG stands for Portable Network Graphics, and it's an open lossless compression format, designed to replace the older GIF format. It's promising; however, it is not the standard, and many Web browsers don't know how to read these files. Keep an eye on this technology, but stick to JPGs and GIFs for now.
So which should I choose?
It all depends on the kind of image you have. GIFs work best for drawings and graphics that use just a handful of colors, such as "line art." JPEGs are typically used for scanned or digital photographs that need a large number of colors. GIFs can also be used for animated and transparent images. PNG does have transparency, but GIF is the only format for animated images. It compresses simple graphics or hand-drawn images very well. PNG is very similar to GIF, but with improved compression. It doesn't support animation, but it's not limited to 256 colors. The biggest drawback is that almost no one uses it.