Teaching & Learning Technology Development Center

File Type


Web browsers recognize only compressed image file formats/types. The most common of these formats are JPEG's (JPG) and GIF's. Each of these file types have special characteristics that will dictate what type to use to achieve the resulting image your viewer will see; i.e., transparent .gifs, animated .gifs, full range of color .jpgs.


 
map of city of Eau Claire saved as j-peg file

Scanned grayscale
saved as a .jpg (17K)

map of city of Eau Claire saved as a gif file

Scanned grayscale
saved as a .gif (10K)

black & white photo save as jpg

Scanned True Color
saved as a transparent gif

black & white photo saved as gif

Scanned True Color
saved as a .jpg

The image of the leaf above left is the same as the JPG above right, however it was saved as a transparent gif using the Help/Export Transparent Image... option in Photoshop. Notice the white background of the JPG was selected to be transparent to the browser and this Photoshop wizard walks you through the steps to create the resulting online image. All images exist in a rectangular world. If you want the image to appear in a colored table cell or over a background image as a freeform object, such as the one on the left, you will choose the transparent gif file format.

 

color spectrum saved as jpg

Continuous color .jpg

True Color Mode (Millions of colors)
The more JPG compression applied to the uncompressed image the lower the quality of the resulting image.

 

color spectrium saved as gif

Restricted palette .gif

Gifs can have a total color palette of 256 or less colors, because of this color banding can result. See example above.

 

File Type | File Size | Thumbnails | Others | Photoshop
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Gene Leisz (leiszgj@uwec.edu)
Updated: August 28, 2003