Computer Science 1033A/B Lecture 5: Lec5 - Picture Compression and the Internet

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

Document Summary

Lossless compresses original bits and byte, but does not lose the original information about the picture. When you reopen the file, all the info about the picture is still there no info is lost. When compressed, the original information is lost. The least necessary parts of the image are the parts of the image that are discarded. Different types of images use algorisms for compression. Common compressed image file formats are: gif, jpg, png. Huffman coding -> more common letters use less bytes (e,o,s,t,r,etc. ); less common letters use the larger byte codes (q,x,z,etc. ) Humans notice changes in brightness more than changes in colour lossy discards the slight difference in colour rather than brightness. Used primarily for cartoons, not good enough quality for photographs. Lossless compression, except for the first time that a jpg is getting compressed to a gif. Can chose a colour to be transparent (can"t do that with a jpg)