I have been studying about boundary discontinuity in DFT and why it is not used as transform in image compression. What i understand is that DFT is N periodic and that causes a discontinuity at the boundary. This means that more number of terms are needed to represent the function and the rate of convergence is slow.
Can somebody explain as to what does it mean when they say that "more number of terms are needed to represent the function?" . And how does it help to use DCT which is 2N periodic?
Reference article is at : http://en.wikipedia.org/wiki/Discrete_cosine_transform