Do any of you have any format preference (GIF or JPEG) for websites? Should we change the graphics to JPEGs? Also, do you think the popups are user-friendly?
The JPEG algorithm for rendering pictures is technically a "lossy" procedure in that when it compresses the picture it discards some information. What it does is to sample small areas of what were originally color photographs (the P in JPEG stands for photograph) and reconstruct the picture using several techniques including representing large areas of a single color with summary instructions rather than giving you repetitive pixels, and by choosing intermediate hues to summarize areas where the original might have used more pixels of different colors. Despite the fact that it is technically lossy, it works extremely well and, particularly when you make changes to an image's size, can give you better results than retaining the image in .gif format. The advantage of the JPEG format is a significant reduction in size of the photograph which will speed its download speed noticeably without any perceptible loss in clarity or brilliance. If you experiment with turning Gifs into smaller Jpegs you can judge the results yourself.
The JPEG procedure falls short, however, when it comes to rendering things like drawings with sharp straight lines such as org charts and diagrams. If you have a row of black pixels with adjacent rows of white pixels in the original gif you will see a thin straight line. The JPEG algorithm can not sample and compress this kind of information without losing clarity.
So the rule is: Use Jpegs for photos and use Gifs for diagrams.
Jack
