The cpdf tool is run afterwards to make sure the final PDF is fully optimized (lossy). High Compression - Uses Ghostscript to compress images within PDFs, but does poorly on PDFs which contain images of text (which is what you get when you scan a document and don't perform OCR on it).Pixel Perfect - Uses the cpdf tool from Coherent PDF, and requires an API key (lossless).If an API key is entered, then GIF files will be processed via the API. Thus to edit an optimized GIF, you need to use Gifsicle's -unoptimize option. While Gifsicle does various optimizations, it excels in removing pixels that are duplicated in animations. There is only one level here, and it uses Gifsicle.
![gifsicle lossy gifsicle lossy](https://64.media.tumblr.com/bb53d79cd7bcb0f32b799c9d53a1956d/tumblr_pxz8nnJMMF1xf5evlo1_500.gif)
![gifsicle lossy gifsicle lossy](https://scd-systemcenterdude.netdna-ssl.com/wp-content/uploads/2020/01/highperfromance.gif)
When we use the term "Pixel Perfect", this is lossless compression.