The field of information theory for calculating how much data can be thrown away while minimising distortion is called rate-distortion theory, and the term for compression with some intentional data loss is lossy compression. This article on JPEGs is an interesting start on some lossy compression techniques, in particular the explanation of Discrete Cosine Transforms. https://parametric.press/issue-01/unraveling-the-jpeg/
The field of information theory for calculating how much data can be thrown away while minimising distortion is called rate-distortion theory, and the term for compression with some intentional data loss is lossy compression. This article on JPEGs is an interesting start on some lossy compression techniques, in particular the explanation of Discrete Cosine Transforms. https://parametric.press/issue-01/unraveling-the-jpeg/