1. FILE COMPRESSION Lossy vs Lossless

2. Why compress a file? To save storage space. To speed up data transmission.

3. Lossless Compression Some files will not work at all if information is lost during compression. These files must use lossless compression. An example is a computer program. If a line of code is missing, it won’t run correctly.

4. Lossy Compression In some files, some information can be removed without causing the file to stop working. Lossy compression usually reduces the quality of a file.

5. Image Compression JPEG is a form of lossy image file compression. The number of colours stored in the file is reduced, by grouping similar colours together. A high level of JPEG compression can cause unwanted visual “artefacts” such as blurring or “blockiness”.

6. Video Compression Lossy compression is currently necessary for streaming video over Internet connections. Colour information can be reduced, as with JPG images. How else could a video file size be reduced?

7. Common Internet File Types What information do these common Internet files contain?.pdf.mp3.svg.mp4.js.css.html.gif.jpg

8. Investigation Challenge! For each of these (less well known) file types, find out: What does it contain?Is it compressed?.flac.xml.tiff.gbs