I have to compare the compression capacity of different transformations on the same signal. The explanations were very brief, but i have to compare some energy thresholds(e.g. 50% of the total energy) in terms of the number of coefficients containing that energy. We were only shown a graph of Spectral Power over normalized frequency.
It's unclear to me how to go about comparing these transforms. Isn't the Spectral Power an FFT of that signal? Do i have to compute the DCT and then do an FFT over the resulting signal? Also, how do i determine how mant points contain a certain amount of energy?