GIF vs JPG

This picture can give you some idea of how a low-quality gif and a low-quality jpg differ. Note that the gif becomes "dotty" and the jpg becomes "squirmy." With this image, the gif looks a lot better.

Here you can see the effects of low-quality gif compression on gradients. They become banded and lack smooth transitions compared to the jpg.
GifJpg
13.8Kb    9.3Kb
 

 

Why the jpg format is so good for photos. The original picture is 153K.

jpg 60%
9K

At 9k, this picture is less than 6% of its original size.

gif 256 colors -
35K

At 35k, this picture is about 6 times as big as the high-quality jpg. A photo with more colors would have an even larger file size as a gif and be even lower in quality.


(Eye picture courtesy of Kam)

jpg 1%
2K

At 2k, this picture has a very small file size, but is of very poor quality.


Click on the photos to see the differences more clearly.

gif 16 colors
9K

At 9k, this picture has the same file size as the high-quality jpg, yet shows the lack of color and the banding that is characteristic of photos saved as gifs.

       

Why the gif format is so good for drawings

On the other hand, logos, cartoons and other images with large areas of flat color look better and have a smaller file size if you save them as gifs. If your screen has high enough resolution, the logo on the left below will look much crisper and have a much smaller file size (5K) than the logo on the right (9K).

 

Why not to save pictures with hard edges in jpg format

The picture on the left is saved as a jpg at high quality. A few extra gray dots. The picture on the right is saved as a jpg at low quality. Very low quality.
The middle picture is saved as a jpg at medium quality -
note the presence of many gray dots.