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MA - MAsk - using circular radii

(4/23/97)

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. Operation works for both 2-D and 3-D images.

SEE ALSO

MA L [Mask - a line across image]
MA X [Mask - 1D, in sample direction]
MA Y [Mask - 1D, in row 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. Sample Outputs: H_IMG026, H_IMG027]

.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 (the old 'CA I' operation).]

.(D)ISK, (G)AUSSIAN EDGE, OR (T)RUE GAUSSIAN: D/G/T
[Enter 'D' for a sharp disk-profile cutoff, (for 2D image only:) 'G' for a piece-wise mask (no modification inside a circle with the specified radius, and 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 mask].

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

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

.MASK CENTER COOS (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 COOS (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 'G' was specified in response to the '(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

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