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Graphic Formats Part 2

© Anna Morvee

There are several file formats to save your graphics and photos. Knowing which is the best for you will aid you in having the best quality photo, graphic or project.

JPEG or JPG is the most common file format for images and photos. It is used because it is a small file size and best used for the web. JPG's consist of 16 million colors verses the 256 colors of a GIF. GIF's are used mostly for animations.

JPG's are raster graphics made up of small squares or pixels. Each time a JPEG is saved, it looses quality, as the data for the colors used is stored in each pixel. JPG's also compress well saving space and download time if a picture is viewed on the web. JPG's are useful for photos when the photo is large and the DPI (dots per inch) is high enough. In order to get a good printout the resolution needs to be 150 DPI or higher. Usually 300 DPI is the most common and the quality of the print out is clear, rather than blurry. Most web graphics and photos are saved at a resolution of 72 DPI as this is the maximum resolution displayed on a monitor and it reduces the file size.

GIF's are 256 colors and are raster format. GIF's have two qualities that you won't find with other raster formats such as BMP's, JPG's or WMF's. GIF's support animations and transparent backgrounds; blending in to the background color.

PNG's are becoming more popular because they can be used in other programs with a transparent background, allowing you to layer the graphic without having the "white" box around the image that you will find with JPG's. In addition, the PNG format supports animations, however the PNG format has not caught on and GIF's are still the favorite for animations.

Vector graphics are made up of lines and curves based on mathematical equations. The most common raster graphic is the WMF or Windows Meta File. You can resize the graphic without loosing quality or the image becoming distorted, as you would see in a raster graphic.

The most common file extensions are:
Raster:
JPG or JPEG
BMP or bitmap: no compression, larger file size
TIFF: most common for commercial printing, no compression and large file size.
GIF: Used for animations and transparent backgrounds. Doesn't print well, not recommended for printing unless you are printing line art or clip-art with 256 colors or less.