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Chapter 11. preparing images & multimedi... > how compression works - Pg. 218

preparing images & multimedia for the web 1. 2. 218 Lossless compression squashes a file in a way that allows it to completely recover, with no information or quality lost. Lossy compression also squashes a file down to size, but some information is lost in the process. Once lost, it can't be restored. JPEG compression produces different results depending on the level of compression. The more you compress, the smaller and rougher your image will be. The original image (a TIFF file) was 53K. Image 1 is 35K. This image was saved at level 12 for "Maximum" quality. It's nearly identical to the original. Image 2 is 15.8K. This JPEG was saved at level "8." It lost a bit of detail, but looks good, considering it's half the size. Image 3 is 7.5K. This JPEG was saved at level "1" for "Low" quality. And it shows. So, lossless compression re-creates the original file exactly as it was. And lossy compression re- interprets it, producing an approximation of the original. Lossless compression is the ideal we're striving toward. But right now, lossy compression is often the only choice. For video production in particular, there's just no way to deliver (or even work with)