Howtosignalprocessing
- Why use DCT instead of DFT?
- What is the main difference between DCT and DFT?
- Is DCT better than DFT?
- What is phase DFT?
Why use DCT instead of DFT?
> 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.
Is DCT better than 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.
What is phase DFT?
The phase is the arctangent of the ratio of the imaginary and real parts and is usually between π and -π radians, or 180 and -180 degrees. For real signals (x[i] real), such as those you obtain from the output of one channel of a DAQ device, the DFT is symmetric with properties given by the following equations.
