Digital Cameras : A SearchMeSilly Guide

This is a way by which the files are reduced in size allowing more images to be taken and stored. Many cameras will allow you to select the compression setting or the resolution at which the image is stored. You can purchase cameras which allow images to be stored in ‘CCD raw mode’, which has no compression.

File formats will vary between cameras. Some are specific to themselves while others have a more generic type. ‘EXIF’ (Smartmedia) is supported by Kodak and Fuji and ‘CIFF’ (CompactFlash) by Canon, Nikon and Pentax.

In order to compress an image, there are two key elements. Firstly, which data within the image can be repeated? If a single colour is repeated over many pixels, it does not need to be stored several times. Instead, the information is saved once along with the reference points of the other pixels. Secondly, what information has no value and can therefore be discarded.

• Lossless - A term describing a data compression algorithm which retains all the information in the data, allowing it to be recovered perfectly by decompression.
• Lossy - A term describing a data compression algorithm which reduces the amount of information in the data and therefore shrinking the file size. Information is discarded which is deemed less important or may be recovered via interpolation methods.