dctAsync function
DCT performs a forward or inverse discrete Cosine transform of 1D or 2D array.
For further details, please see: https://docs.opencv.org/master/d2/de8/group__core__array.html#ga85aad4d668c01fbd64825f589e3696d4
Implementation
Future<Mat> dctAsync(InputArray src, {int flags = 0}) async =>
cvRunAsync((callback) => cffi.core_DCT_Async(src.ref, flags, callback), matCompleter);