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MA X - MAsk - 1D, in sample direction

(9/23/96)

PURPOSE

Masks a specified image with a circle of specified radius and background. The 'X' option cause the flanks in the X direction to be masked off beyond the diameter = 2*radius. This operation is for 2D images only.

SEE ALSO

MA [MAsk - using circular radii]
MA L [Mask - mask a line across image]
MA Y [Mask - 1D, in row direction]
MM [Mask multiplication]

USAGE

.OPERATION: MA X

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

.OUTPUT FILE: H_IMG031
[Enter the name of the output file.]

.OUTER & INNER RADII: 12.0
[Enter the radius of the mask circle, in pixels.]

.(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 system asks:

.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.]

This question is asked for the 3D file only.

.MASK CENTER COOS (NSLICE): 45
[This question is asked for the 3-D file only.]

If a 'G' was specified in response to the ".(D)ISK OR (G)AUSSIAN:" prompt, SPIDER asks]:

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

SUBROUTINES

MASK

CALLER

UTIL2

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