 |
 |
|
|
| File Edit Options Process Analyze Video Macros Stacks SEM SPM Windows Help |
Sharpen Shadow Find Edges Rank Filters Dither Convolve PlugIn Filters
Enhance Contrast Equalize Fix Colors Differential Curvature Unsharp Mask Hough Transform |
FFT Inverse FFT Display Power Spectrum Swap Quadrants Select Largest Square Select Longest Line Autocorrelation Make LEED into FFT Inverse FFT of LEED |
Swaps quadrants
1 and 3 and quadrants 2 and 4 of the active image. Requires an 8-bit
image whose height and width are equal and a power of two. Quadrant
swapping is performed automatically every time a power spectrum is
computed. In the normal, un-swapped, state, the power spectrum's
central peak is distributed among the four corners of the image. While
this is the format used in all computations, it doesn't correspond to
nature's FFT analog, the diffraction pattern. This command is useful
because crosscorrelation and autocorrelation operations (the 'cMul'
operator in Image Math) result in
inherently un-swapped space domain images, yet like power spectra,
correlation functions are often displayed in quadrant swapped format.
The Swap Quadrants command lets you choose the format you desire.
|
|
Steve Barrett November 2014 |
|