Difference between dct and dst

1. Why is DST preferred over DCT?
2. What is the main difference between DCT and DFT?
3. Which is better DCT or DFT?
4. Why DCT is preferred for image processing?

Why is DST preferred over DCT?

> DCT is preferred over DFT in image compression algorithms like JPEG > because DCT is a real transform which results in a single real number per > data point. In contrast, a DFT results in a complex number (real and > imaginary parts) which requires double the memory for storage.

What is the main difference between DCT and DFT?

DCTs are equivalent to DFTs of roughly twice the length, operating on real data with even symmetry (since the Fourier transform of a real and even function is real and even), whereas in some variants the input or output data are shifted by half a sample. There are eight standard DCT variants, of which four are common.

Which is better DCT or DFT?

This is why DCTs...generally perform better for signal compression than DFTs and DSTs. In practice, a type-II DCT is usually preferred for such applications, in part for reasons of computational convenience. Additionally, you may find that this answer is useful too (from math.stackexchange.com).

Why DCT is preferred for image processing?

1) The DCT is real-valued instead of complexity (i.e., it involves magnitude and phase) such that it is easier to be implemented. 2) The DCT is more efficient for illumination variation estimation than the DWT. 3) The DCT approach is similar to the homomorphic filtering, which has been used for contrast enhancement.