Discrete Fourier Sine and Cosine Transforms
The discrete Fourier sine and cosine transforms (DST and DCT) can be used to decompose or represent a given digital signal (that is, discrete) in the form of a set of sums of sines and cosines. Four transform types are possible.[more]
In the graphics, the initial signal is converted forward and back by the selected discrete Fourier transforms. For specific cases, either a cosine or a sine transform may be a better representation of the original signal than a combination of sine and cosine terms.[less]
The inverse transforms of types 1, 2, 3, and 4 are 1, 3, 2, and 4, respectively.