MNFNR

Description

Attempts to remove noise in a single image band using a procedure based on the Maximum Noise Fraction transformation.

Parameters

Name	Type	Length	Value range
Input: Input raster channel(s)	Raster port	0 - 1024
Wavelength Interval	Float	0 - 2
Valid Bands Only	String	0 - 1	YES \| NO Default: NO
Sampling Interval for X, Y	Integer	0 - 2	1 - Default: 1,1
InputNoisyChannel: Channel containing noisy band *	Raster port	1 - 1	1 -
Output: Output corrected channel	Raster port	0 - 1024
Report	String	0 - 192	See parameter description

* Required parameter

Parameter descriptions

Input: Input raster channel(s)

Specifies the input channel(s) to be used for the noise reduction transformation.

Wavelength Interval

Specifies that the selected bands are to be restricted to those whose center wavelength is either inside or outside a closed interval, specified in nanometers. By default, no restriction is applied.

The wavelength interval may be specified as follows:

WLENINT = a,b: restricts selected channels to those containing bands with a center wavelength w such that a <= w <= b
WLENINT = -a,-b: restricts selected channels to those containing bands with a center wavelength w such that w < a or w > b
WLENINT = : no restriction is specified

This parameter has no effect if the input file contains no band center wavelength metadata.

Valid Bands Only

Specifies whether the selected bands are to be restricted to those with "plot" or "bmask" (begin mask) quality values. The default is NO.

This parameter has no effect if the input file contains no band-validity metadata.

Sampling Interval for X, Y

Specifies the X and Y sampling interval within the specified input window.

InputNoisyChannel: Channel containing noisy band

Specifies the input channel containing the noisy band to correct.

Output: Output corrected channel

Specifies the output channel to recevie the corrected image.

Report

Specifies where to direct the generated report.

Available options are:

LOG: generates a report on the terminal (default)
<modulename.RPT>: appends a report to the module's RPT file
DISK: generates a report on file "IMPRPT.LST"

Details

MNFNR performs the following:

Applies a maximum noise fraction (MNF) transformation to the set of bands stored in the specified input channels (DBIC and NOISCHN).
Sets the transformation output component containing the most noise to the mean value for that component image.
Applies the inverse transformation.
Overwrites the specified noise channel (NOISCHN) with the corresponding inverse transformation result.

MNFNR is typically used in a case where a set of image bands contains one band that is considered to have significantly more noise than the others, and it is desirable to transform that band such that its noise content is close to that of the other bands. In this case, it is not necessary to know the noise variance in any band in order to define the MNF transformation.

The application of MNFNR is equivalent to replacing the noisy band (NOISCHN) with the linear combination of the other bands that best approximates the noisy band, in the least-squares sense.

MNFNR performs the same computation whether or not the specified noisy channel (NOISCHN) is included in those specified with DBIC.

MNFNR may be run multiple times to attempt noise removal on multiple bands of a data set. In each run, only one of the noisy bands can be specified as input (NOISCHN and DBIC).

Algorithm

The details of the computation used in program MNFNR may be obtained from Section III.A of the following paper:

Green, A. A., M. Berman, P. Switzer, and M. D. Craig, "A Transformation for Ordering Multispectral Data in Terms of Image Quality with Implications for Noise Removal", IEEE Transactions on Geoscience and Remote Sensing, Vol. 26, No. 1 (1988), pp.65-74.

References