Filter

Arithmetic
These commands operate on the image on a pixel-by-pixel basis. The commands support both real and complex-valued images. The available arithmetic commards are:

Invert	Negate pixel values.
Log	Take natural logrithm of pixel values.
Exp	Take natural exponent of pixel values.
Square	Take square of pixel values.
Square root	Take square root of pixel values.

Frequency Based
These commands perform Fourier and inverse Fourier transformations of images. By default, the transformations will automatically convert images between Fourier to natural orders as expected. For example, 2-D FFT will transform the points into natural order after the Fourier transform. Similarly the inverse, 2-D IFFT, will reorder the points from natural order to Fourier order before applying the inverse Fourier transformation.

As you would expect, images that undergo frequency filtering will be complex-valued after than filtering. Only the real component is shown by CTSim. However, CTSim does have options for converting a complex-valued image into a real-valued image via the Magnitude and Phase filtering commands.

The available frequency-based filtering commards are:

• 2-D FFT
• 2-D IFFT
• FFT Rows
• IFFT Rows
• FFT Columns
• IFFT Columns
• 2-D Fourier
• 2-D Inverse Fourier
• Shuffle Fourier to Natural Order
• Shuffle Natural to Fourier Order
• Magnitude
• Phase