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ISIS Application Documentation


deriv

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Apply horizontal or vertical derivative

Description
Categories
Groups
Examples
History


Description

This program will apply a horizontal or vertical derivative to a cube. This will highlight edges in the image created by groups of contrasting DN values. The horizontal derivative utilizes a two sample by one line boxcar convolution for its solution, and will highlight horizontal linear changes. The vertical derivative utilizes a one sample by two line boxcar convolution for the output, and will highlight vertical linear changes. Please refer to the following 2 by 2 pixel example image:

In this image, the horizontal derivative for A would be:

        A_NewDN = A - B
    

The vertical derivative for A would be:

        A_NewDN = A - C
    

NOTE: If this program needs to do calculations where special pixels are involved, it will simply output NULL. If this causes undesireable results, you should run the image through the stretch program to change all special pixels to valid data. For example, if you have a number of HRS pixels, you might want to stretch those to 255 prior to running the deriv filter.


Categories


Parameter Groups

Files

Name Description
FROM Input cube
TO Output cube

Derivative Direction

Name Description
DIRECTIONDirection of derivative

Files: FROM

Description

Use this parameter to select the filename. All bands within the file will have the derivative applied.

Type cube
File Mode input
Filter *.cub

Files: TO

Description

This is the output file.

Type cube
File Mode output
Pixel Type real

Derivative Direction: DIRECTION

Description

This chooses the derivative direction. The possibilities are: HORZ which uses a 2x1 kernel and VERT which uses a 1x2 kernel.

Type string
Default HORZ
Option List:
Option Brief Description
HORZHorizontal derivative (2x1) The horizontal derivative uses a 2x1 kernel.
VERTVertical derivative (1x2) The vertical derivative uses a 1 x 2 kernel.

Examples


Example 1

Horizontal

Description

Use horizontal derivative option.

Command Line

deriv f=peaks.cub t=deriv.horz d=h
In this example the derivative direction is horizontal.

GUI Screenshot

Derivative Gui

Example Gui

Screenshot of GUI with parameters filled in to perform a horizontal derivative of the input image.

Input Image

Input image

Input image for deriv

Parameter Name: FROM

This is the input image for the horizontal direction option of deriv.

Output Image

Output image showing results of the deriv application with direction: horizontal.

Output image for deriv

Parameter Name: TO

This is the output image for the horizontal example of deriv. The horizontal features fade and vertical features are enhanced.


Example 2

Vertical

Description

Use vertical derivative option.

Command Line

deriv f=peaks.cub t=deriv.vert d=v
In this example the derivative direction is vertical.

GUI Screenshot

Derivative Gui

Example Gui

Screenshot of GUI with parameters filled in to perform a vertical derivative of the input image.

Input Image

Input image

Input image for deriv

Parameter Name: FROM

This is the input image for the vertical direction option of deriv.

Output Image

Output image showing results of the deriv application with direction: vertical.

Output image for deriv

Parameter Name: TO

This is the output image for the vertical example of deriv. The vertical features fade and horizontal features are enhanced.


History

Tracie Sucharski2002-12-24 Original version
Tracie Sucharski2003-01-28 Fixed application name in xml file, misnamed as gradient.
K Teal Thompson2003-04-10 Added examples.
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
Brendan George2005-11-07 Modified to handle special pixels
Jac Shinaman2007-02-08 Updated xml documentation with examples