Computer Science 1033A/B Lecture Notes - Lecture 5: Dither, Gif, Lossless Compression

• School: Western University
• Department: Computer Science
• Course: Computer Science 1033A/B
• Professor: Laura Reid

Document Summary

Raw files (. raw): are files that have no compression, so they have true colours ( For an image, compress as much as you can without losing quality. Lossy: when compression occurs, some of the original information is lost, the information that is lost is one that will be least missed or noticed, cannot get this info back once it is discarded. All file formats use different compression algorithms (ex. Huffman coding - rather than ascii (each letter is 8bits or 1 byte) use the least number of bits for common letters and more bits for less common letters. The type of image we are trying to compress will determine the best file format to choose (jpg, gif, or png) Cross platform (works on macs, windows), does not require a plug-in. 256: not great for photographs but good for clipart, logos, animation. Looks for large blocks of area that all have the same colour!