Transform coding

Transform coding is a method for data compression to compress signals like audio signals (1-D) of images (2-D). In transform coding, first a frequency transform is applied. This has the advantage that the resulting coefficients have a statistically significant distribution and can be modelled and compressed more easily.

This means: After the transform, some coefficients are predictably greater, others smaller. Thus, some coefficients can be neglected (lossy compression) and/or entropy encoded (lossless compression).