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ISIS Documentation

cubenorm

Normalize columns or lines in a cube

The program accomplishes the fairly straightforward task of taking an input cube and outputting normalized values. These values may be represented as a table, PVL (parameter value language), or an entire output cube.

Normalization may be done with respect to lines or with respect to columns. If the user were to normalize by line, the program would take a pass through the data in order to determine statistics for each line. Cubenorm will then pass through each pixel again and normalize each one based on the line in which that pixel is located.

The normalization itself may be thought of as applying either a multiplicative correction or a subtractative correction. Consider the average of a column of data. Each pixel may be normalized by subtracting a normalization factor or multiplying by a normalization factor. Additionally, the user may decide to use a normalization factor based on the median instead of the average.

Categories

Related Objects and Documents

Applications

History

Eric Eliason2004-06-15 Original version (as colnorm)
Drew Davidson2005-07-06 Added options for subtractative corrections
Drew Davidson2005-07-06 Added process by line option and rename to cubenorm
Drew Davidson2005-07-06 Modified unit test to take new options in to account
Jeff Anderson2005-09-09 Major reworking and bug fixes
Drew Davidson2005-10-24 Specialized to run using input files.
Kris Becker2007-01-11 Incorporate UA cubenorm_plus version functionality
Christopher Austin2008-03-17 Changed a single valid pixel's RowCol's Standard Deviation to 0 instead of Isis:Null. When reading in a table file, all Standard Deviations less than 0 are considered 0.
Steven Lambright2008-05-13 Removed references to CubeInfo
Steven Koechle2008-09-02 Fixed check in getstats method that sees whether you are processing by line or column.
Steven Lambright2009-07-30 Removed redundancy of having static global variables

Parameters

Files and options

Use this parameter to select input file
Type cube
File Mode input
Filter *.cub

Output file with input columns divided by the column average
Type cube
File Mode output
Pixel Type real
Internal Default No Output file will be created

Statistical output of each column (band #, column #, valid pixels, average, median, std, min, max)
Type filename
File Mode output
Internal Default No Output file will be created

Specify the format type of the statistics file, either use tabular or PVL style format.
Type string
Default TABLE
Option List:
Option Brief Description
TABLE Create TABLE output Statistics data to be generated in tabluar form, each sample column is placed in a row in the tabluar output.
PVLCreate PVL output Statistics data to be in PVL (Parameter Value Language) format

Optional Statistics Source

This option is intended to be used when the statistics come from a source other than the input cube (default). cubenorm initial derives all its statistics from the input cube and applies it as specified by the user in the same run. This works for most conditions but does not works so well with abrupt changes in brightness such as craters or poles.

With this option, it is now possible to have the statistics come a file in a format compatable with the STATS output file. This can be a TABLE or PVL formatted input file. This allows statistics from other cubenorm runs to be used as input statistics source. It also allows intermediate processing on the FROM stats to apply additional smoothing or culling techniques.

Type string
Default CUBE
Option List:
Option Brief Description
CUBEStatistics are computed from FROM input cube This is the old behavior. The statistics are computed from the input cube as specified by the FROM parameter. They are also applied to the TO file if specifed in the same run.

Exclusions

  • FROMSTATS
TABLEStatistics are provided in FROMSTATS in TABLE format This option requires a filename in FROMSTATS with TABLE formatted data. This format is the same format as is generated in the STATS output file.
PVLStatistics are provided in FROMSTATS in PVL format This option requires a filename in FROMSTATS with PVL formatted data. This format is the same format as is generated in the STATS output file.

This optional file provides the statistics that are applied to the input FROM file. Its format must be TABLE or PVL and consistant with the STATS file output format.

If this option is utilized, the statistics gathering step is bypassed.

Type filename
File Mode input
Filter *.txt

Normalization options

This is the direction in which normalization occurs. If the user chooses to process by column, they intend to take in an entire column of data and normalize based on the average or median of that column for each pixel in that column. If they choose to process by line, they intend to do the same for each pixel, but with respect to lines.
Type string
Default COLUMN
Option List:
Option Brief Description
COLUMN Normalize columns Gather statistics by moving left to right through the cube
LINENormalize lines Gather statistics by moving from top to bottom through the cube

This option is used to select if column or line is normalized using its average or median
Type string
Default MEDIAN
Option List:
Option Brief Description
MEDIANUse column/line median when normalizing This option will use the median of the column/line when normalizing each column/line
AVERAGEUse column/line average when normalizing This option will use the average of the column/line when normalizing each column/line

This option is used to select select how normalization coefficients are applied, either subtracting or dividing by the average or median.
Type string
Default DIVIDE
Option List:
Option Brief Description
DIVIDEDivide column/row by its median/average This option will divide each column (or row) by its normalizer (median or average).
SUBTRACTSubtract median/average from column/row This option will subtract the normalizer (median or average) from each column (or row).

This option is used to preserve the average/median of the input image. If turned off, the output image average of the data will be one (unity) for the DIVIDE mode or zero for the SUBTRACT mode.
Type boolean
Default TRUE