Now that we have discussed the type of images that exist in a digital world, we need to understand some of the different ways these images can be saved. There are many different file formats for saving images. Each has it's strong and weak points when it comes to storing different types of image files. Some formats cannot store more than 256 colors, some cannot be compressed, and others produce enormous files. If you are not familiar with the choices, this blessing of a wide assortment can become confusing. In this section we will try to take some of the mystery out of these formats with strange-sounding names. For some, the question will be "What is an image file format?" The answer is, an image file format defines a way of storing an image and any related information in a way that other programs can recognise and use. Each format has it's own unique form, called a file structure, for saving the image pixels and other related file information such as resolution and color depth. Each format is unique and generaly identified by it's 3-letter file-extension. For example, the 3-letter extension CPT on a filename identifies the file format as a Corel Photo-Paint file. This extension is important because many programs use the 3-letter extension to identify the type of File Import Filter to select. If the wrong extension or a unique extension is used, it may be difficult, perhaps impossible to import the image. Corel Photo)Paint is aware of the color depth of the image you are attempting to save and changes the selection of available file format choices automatically. For example, if you have a 32-bit color image, the drop-down list will be reduced from teh normal selection to the few file format choices that support 32-bit. The Wavelet compression format represents another entry in the field of image file compression that was introduced in with Photo-Paint 7. Because there are dozen of file formats, it would be confusing to try to cover them all. Instead we will look at the major ones supported generally. BMP (Windows Bitmap) is the native image format for Microsoft Paint, which is included with every copy of Microsoft Windows and nearly supported by avery Windows based program. This is a popular format, but it does not offer compression and is generally used only for small image file. Compuserve created GIF a long time ago as a means of compressing images for use over their extensive online network. Many people think Compuserve owns it. In fact, they bought the rights to use a patented compression scheme (LZW) from Sperry-Univac. GIF has become a very popular format, especially now that everyone is jumping on the internet. As a way to send pictures over the phone lines, it can't be beat. It has a major limitation of supporting only 8-bit images. There's no compression offered when saving in this format because it is already a compression format on it's own. Compression Formats existing as file formats are 89a and 87a. These formats provide the capability to save a file with transparancy and interlacing options, which is becoming increasingly important for creating Web grafics for use on the internet. PCX is one of the original file formats, created by Z-Soft for PC Paintbrush back when Noah was working on his ark. It is unquestionably one of the most popular image file formats around, mainly because PC Paintbrush is the oldest painting program for the IBM PC. The only concern with using PCX images involves importing them into older applications, because the PCX format has been around so long, there are many versions of PCX import filters around, causing it sometimes to be unreadable by one program and readable for another, depending on the filters used for each program. EPS stands for Encapsulated Post Script. PostScript is a page description language used by imagesetters and laser printers. This format is a favorite of your friendly neighborhood service bureau. Many people do not think about using EPS format when working with Paint's BMP images because of it's association with vector-based drawings. EPS does work with BMP images ...for a price. By that i mean a BMP image saved in EPS format will be roughly 3 times as large as the same file saved as TIFF format. If you must send work to a service bureau, it may be the only format they will accept, especially for separations.