Using the Fourier Output settings it is possible to select several optional image windows to be displayed when working with the Fourier utilities. Likewise it is possible to define the scaling of the Fourier image and view one of the images in 3D.
When this checkbox is on the Data Window selected in the Preprocess Tab will be shown as an image.
When active the Filter Fourier image is shown
When active the Fourier Image after applying the Filter will be shown in its own window. The FFT Filtered image will use the same scale setting as the original Fourier Image.
Filter Ratio
It is possible to moderate the filter effect by setting the Filter Ratio checkbox on and define a Ratio number. Assume that we are filtering an Image Iorgand that the Inverse Fourier filtering procedure creates and image Ifiltapplying a filter ratio r will then produce an Image
Ir = r Ifilt + (1-r) Iorg.
Thus a ratio of r = 0 will produce the original image and a ratio of r = 1 will produce and image equal to the Inverse FFT Image, while ratios between 0.0 and 1.0 will be a combination of the two images.
When this checkbox is set, the inverse FFT filtered image will be subtracted from the input image and the subtraction result shown in its own window. This serves as a good tool for monitoring what is actually removed from the original image. It might also be used as a primary output as it is complementary to the normal filter output. When a low-pass filter is applied it will in the difference image show up as a high-pass filtered image and vice versa.
When using the Filter Ratio the output from the Filter ratio will be used as input for this function.
It is possible to select any of the images produced by the Fourier Dialog and view these in 3D.