MA - Mask - image using circular mask

PURPOSE

Masks a specified picture with circular masks of specified radii. Pixels in the area inside the inner circle and the area outside the outer circle are set to a specified background.

SEE ALSO

MA L	[Mask - line across image]
MA X	[Mask - image in X direction]
MA Y	[Mask - image in Y direction]
MA Z	[Mask - image in Z direction]
MM	[Mask Multiplication]
MM C	[Mask Multiplication - Continuous]

USAGE

.OPERATION: MA

.INPUT FILE: H_PIC001
[Enter the name of the file to be masked.]

.OUTPUT FILE: PIC002
[Enter the name of the output file.]

.OUTER & INNER RADII: 12.0, 0.0
[Enter the radii of the outer and inner mask circles, in pixels. Pixels in areas outside the outer radius and inside the inner radius are set to background. Enter zero inner radius for no inner radius masking. Enter zero outer radius for inner masking only.]

.(D)isk, (C)osine, (G)aussian edge, or (T)rue Gaussian: D/C/G/T
[Enter 'D' for a sharp disk-profile cutoff, 'C' or 'G' for a piece-wise mask (no modification inside a circle with the specified radius, and cosine/Gaussian-shaped falloff from this radius outwards), or 'T' for a true Gaussian mask.]

.(A)V, (P)REC AV, (C)IRCUMF, OR (E)XTERNAL: P
[Enter 'A' if the background is to be the average of the picture before masking; enter 'P' if the background is to be the average after masking; or enter 'E' if the background is to be specified externally. Enter 'C' if you want the background to be determined by averaging along the circumference of the outer mask].

If 'E' was entered, the following question appears:

.ENTER BACKGROUND: 3.0
[Enter the desired background.]

.MASK CENTER COORDINATES (NSAM, NROW): 50, 15
[Enter the coordinates of the circular mask center. Note that you have to specify coordinates equal to NSAM/2+1, NROW/2+1 if you want the mask center to coincide with the nominal image center.]

The following question appears only when using a 3-D volume.

.MASK CENTER COORDINATES (NSLICE): 45

[Enter the slice number for the circular mask center. Note that you have to specify slice equal to NSLICE/2+1 if you want the mask center to coincide with the nominal volume center.]

If a 'C' was specified in response to the '(C)osine, (D)isk or (G)aussian:' prompt, the following question appears:

.WIDTH: 3.5
[Enter the width of the cosine falloff function.]

If a 'G' was specified in response to the '(C)osine, (D)isk or (G)aussian:' prompt, the following question appears:

.HALFWIDTH: 3.5
[Enter the halfwidth of the Gaussian falloff function.]

SUBROUTINES

MASK

CALLER

UTIL2