III (May90) velcal III (May90)
iii -- Produce a 3-phase intensity image from a vmi image
iii input output
List of vmi(phase, modulation, intensity) input images.
List of three-phase intensity output images.
III transforms vmi images to three-phase intensity images. The
vmi image consists of three bands where
band 1 = phase velocity (radians)
band 2 = modulation amplitude
band 3 = mean intensity (adu).
The following definition of the intensity (I) was used
I(t) = I0 [ 1 + M cos (4 w t + V)],
where I0 is the mean intensity (band 3 of input), M is the
modulation amplitude ( band 2 of input), V is the phase velocity (
band 1 of the input), w is the rotation rate of the motor, and t is
time. The three-phase intensities of the output image are
calculated three times during a cycle at 4wt = 0, 2PI/3, 4PI/3.
This module is used to simulate the Fourier Tach response to a
solar velocity test image in TSTIM (the self-test for the VELCAL