Part 1- Graphic File Formats Rearch

http://www.why-not.com/articles/formats.htm#PREVIEW - This link is were I got this information from, for my research about the range of graphic file extensions and the graphic file formats, I have read this information and I thought that it was relevant for my research because it explains what they are.

GIF (Graphics Interchange Format)

The CompuServe GIF is commonly used to upload documents to the CompuServe Information Service and to pass documents between other types of computers. The idea behind designing GIF files was to create the smallest possible image file for uploading and downloading from electronic Bulletin Board Systems (BBS), thus producing a highly compressed format that minimizes file transfer time over phone lines. The compression is accomplished by using the LZW method for indexed color tables.
There are two GIF file versions: 87a and 89a.
Both versions may use an encoding method referred to as interlacing. When an image is saved by using four passes instead of just one, it is called interlacing. On each pass, certain lines of the image are saved to the file. If the program decoding a GIF file displays the image as it is decoded, the user will be able to see the four passes of the decoding cycle. This will allow the user to get a good idea of what the image will look like before even half of the image is decoded. Most communication programs (for BBSs and the InterNet) allow the user to download GIF files and view them as they are downloaded. If the image is interlaced, the user will be able to decide if the image is one they like before half of the download is complete. If the user does not like the image, the download can be aborted. This results in the saving of time and money for the person downloading the image.
GIF files may contain multiple images. 

JPEG (Joint Photographic Experts Group)

JPEG compression economizes on the way data is stored and also identifies and discards extra data, that is, information beyond what the human eye can see.
Because it discards data, the JPEG algorithm is referred to as "lossy". This means that once an image has been compressed and then decompressed, it will not be identical to the original image. In most cases, the difference between the original and compressed version of the image is indistinguishable.
In general, compressed JPEG images have compression ratios of between 5:1 and 15:1. A trade-off does exist between the image quality and the amount of compression. You do not need to decompress images saved in the JPEG format. They are automatically decompressed when they are opened.
 

TIFF(Tagged-Image file Format)

Tagged-Image File Format (TIFF) is used mainly for exchanging documents between different applications and different computer platforms.
The Tagged Image File Format was primarily designed to become the standard format. In order to become the standard, the format was designed to handle just about any possibility. The result of this design provided the flexibility of an infinite number of possibilities of how a TIFF image can be saved.
As a result, no application at all can claim to support all TIFF variations. Some professional applications support many TIFF variations, but there will always be an obscure variation that will cause a problem for some application.
The TIFF format uses 6 different encoding routines:
- No-compression
- Huffman
- Pack Bits
- LZW
- Fax Group 3
- Fax Group 4
In addition it differentiates between types of images in 3 different categories:
- Black and white
- Gray scaled
- Colored
The TIFF format supports LZW method compression for image types.
(This is the same compression used by the GIF format for indexed color.)