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Program Functions
142
phase-wedge image was chosen as default so that regions that are NaN in the original phase-
wedge image are not identified as any visual area.
vSaveFlatROIs.m
This function saves ROIs. A ROIs data structure, the directory string, and the current hemi-
sphere have to be given to the function.
vShowROIs.m
vShowROIs displays overlays on top of functional images, e.g., the visual-area ROIs that are
selected in the list box labeled “Visual-Area-ROIs”.
6.15 SignMap
vCalculateGradients.m
This function creates a matrix of complex values z from phase (ph) and coherence (co) values.
Together with a parameter for edge handling, the computed matrix is given to the function
vGradient. The derivatives in horizontal and vertical directions are returned.
j ph
z
co e×
=
×
.
Equation 25: Complex value
vFieldSignMap.m
This function calculates a visual field sign map based on four flat maps: the phase maps for
ring and wedge stimuli as well as the coherence maps for ring and wedge stimuli. At first, the
gradients for the ring stimulus case and for the wedge stimulus case have to be calculated.
vCalculateGradients is called to perform this task. It generates the phase gradients in the com-
plex domain as described in [Fleet and Jepson, 1990 #55]. The coherence matrices are used as
weights when the gradients are calculated. Since the measured functional data is extremely
noisy, it was tried to blur the flat data before calculating the gradients in vFieldSignMap.
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