Pixels and Compression

Pixels

Understanding Pixels
To anyone entering the digital photo arena, pixels are an important thing to understand. They are the smallest part of the digital picture. Resolution is measured by the number of pixels stored for each photo. For example, when your camera is low resolution, a 640 x 480 picture will have 307,000 pixels and can occupy as much as 1 megabyte of storage. A picture taken at the resolution of 1024 x 768 may end up being 2.5 megabytes. So what do we do?

Compression

General
File compression is used inside your camera to optimize the available onboard camera storage space and to speed up the file migration from your camera to your PC. Digital cameras each have some type of compression they use to accomplish the task of downsizing the file.

Lossless and Lossy
Lossless compression provides an image that is of the same quality as the original but does little to preserve storage space used by the photo. The files are still large. Lossy compression is better at saving file space; but, as the file is compressed more, quality (in actual pixels) is lost along the way. So each type of compression has its problems.

File Formats

Examples
Raw - No compression - formats are not always universally compatible
JPEG - (Joint Photographic Experts Group) - popular but lossy - best for photos
TIFF - (Tag Image File Format) - lossless - big files - most widely used of all the image transfer formats.

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