FFT

This option evaluates the fast Fourier transform of a buffer or data contained in the internal memory array. The calculation is performed on an image containing 256 pixels in the horizontal direction and 128 in the vertical. When operating on a buffer, the resolution is first reduced to this and the image copied to the internal memory array.

Calculate FFT on which buffer (-1 for memory) ?

If positive, this entry specifies the buffer containing the image to be transformed. The selected buffer is made the current output buffer, the resolution reduced to 256x128 pixels, the contents transferred to the internal memory aray and transformed. If an entry of -1 is specified, then it is assumed the data to be transformed is already contained in the internal memory array.

Transform in Both directions, Horizontal only or Vertical only ?

The answer to this question determines whether the image is to be transformed in the horizontal direction only (<H>), the vertical direction only (<V>), or both the horizontal and vertical directions (<B>).

Calculating FFT...

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DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996