Graphics

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Intro Graphics/Images

A wide variety of graphic/image file formats exist. Many are dependent upon particular hardware/operating system platforms, while others are cross-platform independent formats. This introduction will only touch upon some of the most common formats. While not all formats are cross-platform, there are conversion applications which will recognize and translate formats from other systems.

Compression

Almost all formats incorporate some variation of a compression technique due to the large storage size of image files. These can be classified into either lossless or lossy formats.

Lossless formats compress all of the original captured/created data of the image/graphic using algorithms which allow the original data of the file to be recreated without loss of any data, hence the name.

Lossy formats discard data when storing images. The data discarded is in most cases beyond the ability of the human vision system and thus there is no discernible difference between the original image and the compressed image.

Graphic/Image Data Structures

There are two methods for representing and storing graphic/image data in uncompressed form.

Bit-Map Images

A bit-map representation stores the image by storing data about every dot/point of an image. These image points are termed pixels (a contraction for picture element).

Vector / Structured Graphics

A vector graphic file format does NOT store information about every pixel of a graphic. Instead a vector graphic file format is composed of analytical geometry formula representations for basic geometric shapes, (e.g., line, rectangle, ellipse, etc.).

The following pages will help you explore the differences in the two types of graphic/image file formats.