ImageGear .NET v24.12 - Updated
Discrete Cosine Transform and Discrete Sine Transform
User Guide > How to Work with... > Image Processing and Cleanup > Process Images in the Frequency Domain > Discrete Cosine Transform and Discrete Sine Transform

Before using these methods, like other frequency processing methods, ImGearFrequencyProcessing.InitializeFFTW Method() must be called first to enable the support for FFTW.