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ISIS Documentation

sharpen

Sharpen the features in a cube

This program sharpens the edges in the image. The method for sharpening is done by applying a high pass filter to a cube and adding the filter results back to the original image. In general, you will sharpen small features with smaller boxcars and larger features with larger boxcars.

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
Jeff Anderson2002-09-25 Ported to Isis 3.0
K Teal Thompson2003-04-10 Add example.
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
Jeff Anderson2004-02-17 Removed addback option and put it in the highpass program

Parameters

Files

Input cube to filter
Type cube
File Mode input
Filter *.cub

The resultant filtered cube
Type cube
File Mode output

Boxcar Size

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
Default 3
Minimum 1 (inclusive)
Odd This value must be an odd number

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
Default 3
Minimum 1 (inclusive)
Odd This value must be an odd number

Boxcar Restrictions

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

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

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)

Other

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

Example 1

3x3

Use a 3x3 boxcar

Command Line

In this example the boxcar size is the default 3 by 3.
sharpen f=peaks.cub:4 t=sharpen

GUI Screenshot

Sharpen Gui

Example Gui

Sharpen Gui

Screenshot of GUI with parameters filled in to perform a "sharpen"ing of the input image with the default boxcar of 3x3.

Input Image

Input image

Input image for sharpen

Input image

Parameter Name: FROM

This is the input image for the sharpen example.

Output Image

Output image showing results of the sharpen application.

Output image for sharpen

Output image showing results of the sharpen application.

Parameter Name: TO

This is the output image for this example of sharpen. Notice the edges of features are sharper. It is the same as running highpass and adding the highpass output back to the input image.