File Types

There are many file types to choose from when saving your images. We will discuss the following five in detail: JPG, GIF, BMP, TIF, and PSD. All file formats fall into one of two groups: "Lossless" and "Lossy".

Lossless simply means that the file will not loose any image quality when saved. The file may or may not be compressed, depending on the file format.

A lossy compression does loose some quality when saving. However, in many cases, the lost information is not noticeable.

JPG File Format
The JPG (or JPEG) file format is one of the most popular for many reasons.
1. Images can be compressed (lossy type compression) very efficiently with little or no visual image quality loss. A 30:1 compression ratio is not unreasonable.
2. This format can be opened on PC platforms as well as Macintosh platforms.
3. JPG format supports 24 bit color (16.8 million colors).

The above reasons make JPG ideal for saving pictures.

GIF File Format
The GIF file format is another popular choice. It is used for items that do not require a lot of color depth such as logos, icons, buttons (on websites), etc.
1. Images are compressed in a lossless type compression.
2. GIFs are also cross platform (PC/Mac).
3. GIF format only supports 8bit color (256 colors).

BMP File Format
BMP is a Windows format that is not compressed. Its usage is somewhat limited due to these reasons. However, if you want to use a picture for your desktop "wallpaper" (background image), you need to save it in a BMP format.

TIF File Format
TIF is a cross platform lossless file format. Typically, TIF files are not compressed much, if at all. It is used commonly for archival of color images where quality loss of any kind is objectionable.

PSD File Format
This is a Adobe Photoshop file format. It is much like a TIF, except that if the image is comprised of multiple layers, PSD keeps them separate for future editing.

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