Why is the DFT used for spectrograms rather than the DCT?

1. Why is DFT better than DCT?
2. What is the main difference between DCT and DFT?
3. What is the difference between DFT and DCT transform in term of data analysis and compression?
4. What is the relation between DCT and DFT?

Why is DFT better than 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.

What is the difference between DFT and DCT transform in term of data analysis and compression?

The difference between the two is the type of basis function used by each transform; the DFT uses a set of harmonically-related complex exponential functions, while the DCT uses only (real-valued) cosine functions.

What is the relation between DCT and DFT?

DCT is similar to the Discrete Fourier Transform (DFT), but using only real numbers. DCT are equivalent of DFT of roughly twice the length, operating on real data with even symmetry and in some variants the input or output data are shifted by half a sample.