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ISIS Application Documentation

svfilter

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Apply a variance or standard deviation filter to a cube

Overview Parameters Example 1 Example 2

Description

This program applies either a variance or standard deviation filter to a cube. The standard deviation filter is simply the square root of the variance and is selected by setting the FILTER parameter to STDDEV.

Categories

Related Applications to Previous Versions of ISIS

This program replaces the following application existing in previous versions of ISIS:
  • boxfilter

Related Objects and Documents

Applications

History

Eric Eliason1988-05-20 Original version
Tracie Sucharski2002-08-13 Ported to Isis 3.0
Jeff Anderson2002-11-26 Fixed bug which disallowed the standard deviation filter
K Teal Thompson2002-12-03 Add examples.
K Teal Thompson2003-03-28 Make images smaller.
Stuart Sides2003-04-04 Fixed problem with isiscvs not checking in the thumb and image directories.
Kim Sides2003-05-13 Added application test
Stuart Sides2003-05-16 Modified schema location from astogeology... to isis.astrogeology..."
Stuart Sides2003-07-29 Modified filename parameters to be cube parameters where necessary

Parameter Groups

Files

Name Description
FROM Input file
TO Output svfilter cube

Filter Type

Name Description
FILTER Filter type

Boxcar Size

Name Description
SAMPLES Number of samples in boxcar
LINES Number of lines in boxcar

Boxcar Restrictions

Name Description
LOW Valid minimum pixel
HIGH Valid maximum pixel
MINIMUM Minimum boxcar pixel count

Special Pixels

Name Description
PROPAGATEPropagate special pixels
X

Files: FROM

Description

Input cube to filter

Type cube
File Mode input
Filter *.cub
Close Window
X

Files: TO

Description

The resultant filtered cube

Type cube
File Mode output
Pixel Type real
Close Window
X

Filter Type: FILTER

Description

The output of the filter operation is either the variance value or the standard deviation value.

Type string
Default VARIANCE
Option List:
Option Brief Description
VARIANCE Perform variance filter This will output the variance at the center of the boxcar.
STDDEV Perform standard deviation filter This will output the standard deviation at the center of the boxcar.
Close Window
X

Boxcar Size: SAMPLES

Description

This is the total number of samples in the boxcar. It must be odd and can not exceed twice the number of samples in the cube. In general, the size of the boxcar does not cause the program to operate significantly slower.

Type integer
Minimum 1 (inclusive)
Odd This value must be an odd number
Close Window
X

Boxcar Size: LINES

Description

This is the total number of lines in the boxcar. It must be odd and can not exceed twice the number of lines in the cube. In general, the size of the boxcar does not cause the program to operate significantly slower.

Type integer
Minimum 1 (inclusive)
Odd This value must be an odd number
Close Window
X

Boxcar Restrictions: LOW

Description

Valid minimum pixel value that will be used in boxcar computation. If a pixel value is less than LOW then it will not be used when computing boxcar statistics.

Type double
Internal Default Use all pixels
Less Than HIGH
Close Window
X

Boxcar Restrictions: HIGH

Description

Valid maximum pixel value that will be used in boxcar computation. If a pixel value is greater than HIGH then it will not be used when computing boxcar statistics.

Type double
Internal Default Use all pixels
Greater Than LOW
Close Window
X

Boxcar Restrictions: MINIMUM

Description

This is the minimum number of valid pixels which must occur inside the NxM boxcar for filtering to occur. For example, 3x5 boxcar has 15 pixels inside. If MINIMUM=10 then the filter will occur if there are 10 or greater valid pixels. A valid pixel is one that is not special (NULL, LIS, etc) and is in the range defined by LOW to HIGH.

Type integer
Default 1
Minimum 1 (inclusive)
Close Window
X

Special Pixels: PROPAGATE

Description

This option is used to define how special pixels are handled. If the center pixel of the boxcar is a special pixel it will be propagated or set to NULL depending on the value of this parameter.

Type boolean
Default TRUE
Close Window

Example 1

run svfilter

Description

This example shows an svfilter operation using standard deviation.

Command Line

svfilter fr=../IN/peaks.cub:4 t=OUT/svfilter.sd fi=s s=5 li=5
svfilter a Terra image. Use STDDEV filter (fi=s)

GUI Screenshot

svfilter Gui

Example Gui

Screenshot of GUI with parameters filled in to perform an svfilter operation on the input image.

Input Image

Input image

Input image for svfilter

Parameter Name: FROM

This is the input image for the svfilter examples.

Output Image

Output image showing results of the svfilter application.

Output image for svfilter

Parameter Name: TO

This is the output image that results from STDDEV filter.

Example 2

run svfilter

Description

This example shows an svfilter operation using variance.

Command Line

svfilter fr=../IN/peaks.cub:4 t=OUT/svfilter.var fi=v s=5 li=5
svfilter a Terra image. Use VARIANCE filter. (fi=v)

GUI Screenshot

svfilter Gui

Example Gui

Screenshot of GUI with parameters filled in to perform an svfilter operation on the input image.

Input Image

Input image

Input image for svfilter

Parameter Name: FROM

This is the input image for the svfilter examples.

Output Image

Output image showing results of the svfilter application.

Output image for svfilter

Parameter Name: TO

This is the output image that results from VARIANCE filter.