TH F - Threshold - Set pixels above/below Threshold to Fixed value

(5/29/13)

PURPOSE

Replaces all values within an image or volume before/beyond a specified threshold by a specified value. Operation works for both 2-D and 3-D images.   Example.

SEE ALSO

TH [Threshold - Set pixels above/below Threshold to Threshold]
TH C [Threshold - Change all pixels having a specific value in image]
TH M [Threshold - Create Mask based on Threshold]

USAGE

.OPERATION: TH F [nv]

[This operation can return one optional register variable:
Variable Example Receives
First [nv] Number of altered pixels/voxels

.INPUT FILE: IMG001
[Enter the name of the input file.]

.OUTPUT FILE: IMG002
[Enter the name of the output file.]

.ALTER (A)BOVE THRESHOLD, (B)ELOW, OR (C) BOTH SIDES (A/B/C): A
[Option 'A' : Replaces all values greater than the specified threshold with the fixup density vlaue.
 Option 'B' : Replaces all values smaller than the specified threshold with the fixup density value.
  Option 'C' : Replaces all values smaller than the lower threshold or greater than the upper threshold with the fixup density value.

For options 'A' and 'B', SPIDER asks:


.THRESHOLD: 1.2
[Enter the threshold value desired.]

For option 'C' , SPIDER asks:


.UPPER, LOWER THRESHOLD: 1.2, 0.8
[Enter two thresholds between which the original image data are to be preserved.]

For all options , SPIDER asks:

.FIXUP DENSITY: 0.5
[Enter value to be give to pixels before/after the desired threshold(s).]

SUBROUTINES

THRESH

CALLER

UTIL2

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