dstripe

This program uses a combination of lowpass and highpass filters to remove horizontal or vertical stripes in a cube. The steps behind the noise removal technique are:

       output = input - noise
       where noise = highpass(lowpass(input))
    

Suppose an input image had vertical striping noise, like in the example below. The noise can be removed or suppressed by applying a sequence of lowpass and highpass filters. The idea is to create an image containing only the noise and subtract that noise image from the original.

First, we apply a tall (1xNL) lowpass filter to the input image. This produces an image that is essentially a column average. The high frequency information has been suppressed and the vertical noise is left behind. Note however, the average of the lowpass filter matches the original input so we can not subtract the noise quite yet.

Second, we appy a (NSx1) highpass filter to the lowpass image. This effectively suppress the albedo information in the noise leaving only the noise behind. Note that the noise (third) histogram is centered about zero.

Finally, the noise image is subtracted from the original input image resulting in the desired noise-free image. All the steps the program goes through (along with their respective histograms) are illustrated below:

From left to right: Input, Lowpass, Highpass, Output

Description

Name of the input cube which has horizontal or vertical striping

Type	cube
File Mode	input
Filter	*.cub

Description

The resultant cube which will have suppressed or removed striping

Type	cube
File Mode	output
Filter	*.cub

Description

This allows the user to specify which kind of striping noise needs to be removed.

Type	string
Default	VERTICAL
Option List:	Option Brief Description VERTICAL Vertical noise Remove vertical striping from image Exclusions HLNL HLNS HHNL HHNS HORIZONTAL Horizontal noise Remove horizontal striping from image Exclusions VLNL VLNS VHNL VHNS

Description

This is the number of the lines to be used by lowpass

Type	integer
Internal Default	Number of lines
Minimum	1 (inclusive)
Odd	This value must be an odd number

Description

This is the number of the samples to be used by lowpass

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

Description

This is the number of the lines to be used by highpass

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

Description

This is the number of the samples to be used by highpass

Type	integer
Internal Default	Number of samples
Minimum	1 (inclusive)
Odd	This value must be an odd number

Description

This is the number of the lines to be used by lowpass

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

Description

This is the number of the samples to be used by lowpass

Type	integer
Internal Default	Number of samples
Minimum	1 (inclusive)
Odd	This value must be an odd number

Description

This is the number of the lines to be used by highpass

Type	integer
Internal Default	Number of lines
Minimum	1 (inclusive)
Odd	This value must be an odd number

Description

This is the number of the samples to be used by highpass

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

Description

This will delete the noise file after the image is processed.

Type	boolean
Default	TRUE
Exclusions	LPFNOISE NOISE

Description

The results of running lowpass(input)

Type	cube
File Mode	input
Default	lowpass.noise.cub
Filter	*.cub

Description

The results of running highpass(lowpass(input))

Type	cube
File Mode	input
Default	dstripe.noise.cub
Filter	*.cub

This example shows the results of removing vertical striping noise from an image.

dstripe from=../LO_4090_h1.cub to=../result.cub

dstripe Gui

Example Gui Screenshot of GUI with parameters filled in to perform a destriping operation on the input image.

Input LO Image	Input image for dstripe Parameter Name: FROM This is a Lunar Orbitor image with vertical striping.
Striping Noise Image	Noise image from dstripe Parameter Name: NOISE This is a result of the low and highpass filters of the input image.

Output image showing the result of destriping.

Output image from destriping Parameter Name: TO This is the output image that results.