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The Discrete Cosine Transform (DCT) (401 words) |
 | The DCT is similar to the discrete Fourier transform: it transforms a signal or image from the spatial domain to the frequency domain (Fig 7.8). |
| F(u,v) is the DCT coefficient in row k1 and column k2 of the DCT matrix. |
| The DCT input is an 8 by 8 array of integers. |
| DCT - definition of DCT in Encyclopedia (944 words) |
| It is equivalent to a DFT 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), where in some variants the input and/or output data are shifted by half a sample. |
| DCTs are also widely employed in solving partial differential equations by spectral methods, where the different variants of the DCT correspond to slightly different even/odd boundary conditions at the two ends of the array |
| The inverse of DCT-I is DCT-I multiplied by 2/(n-1). |
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