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ISIS Documentation

histmatch

Match histograms of 2 cubes

This program takes in two input images, FROM and MATCH, and uses their histograms to compute stretch pairs. The data in the stretch depends on which matching algorithm is chosen. If Culmulative Distribution Function (CDF) is chosen, the histogram data will be stored into stretch pairs at regular intervals, the default being every one percent between 0.5 and 99.5 percent. If MODE is chosen, only the histogram data at the endpoints and mode are stored. The pixels from the input image are remapped based on the data in the stretch pairs and the results are written to a new cube file. This is useful for tone matching two images. The following figures illustrate what is happening. Band 1 is FROM, Band 6 is MATCH, and CDF and Mode are two different output cubes. The blue line is the histogram and the red line is the cumulative distribution.
Band 1 image Output of CDF algorithm
Band 6 image Output of Mode algorithm
Notice how the endpoints, mode, and overall shape of Band 1's histogram is now roughly equivalent to Band 6.

Categories

Related Objects and Documents

Applications

History

Sean Crosby2006-12-04 Original version
Sean Crosby2007-03-12 Included ability to histmatch input cubes of different sizes
Steven Lambright2008-05-12 Removed references to CubeInfo

Parameters

Files

This file will have its histogram reshaped to resemble MATCH's histogram
Type cube
File Mode input
Filter *.cub

This file's histogram will be matched by FROM
Type cube
File Mode input
Filter *.cub

The resultant cube containing the altered input file
Type cube
File Mode output
Filter *.cub

Algorithm

This parameter specifies how the histogram will be stretched. The options are to stretch by by percentage (CDF), or by mode (Mode).
Type string
Default CDF
Option List:
Option Brief Description
CDFMatch Cumulative Distribution Function Remap image using stretch pairs taken at regular percentage intervals
MODEMatch modes Remap image using stretch pairs based on endpoints and mode

Exclusions

  • INCREMENT

Histogram Options

Minimum cut-off value for the histogram
Type double
Default 0.5
Minimum 0.0 (inclusive)
Less Than MAXPER

Maximum cut-off value for the histogram
Type double
Default 99.5
Maximum 100.0 (inclusive)

Percentage increment for the histogram
Type integer
Default 1
Minimum 1 (inclusive)
Less Than MAXPER

Example 1

Peaks histogram matching with CDF

This example shows the results of histogram matching using the cumulative distribution function.

Command Line

Use CDF matching to adjust Band 1's histogram to resemble Band 6's histogram
histmatch from=../peaks.cub+1 match=../peaks.cub+6 stretch=cdf to=../result.cub

GUI Screenshot

Histmatch Gui

Example Gui

Histmatch Gui

Screenshot of GUI with parameters filled in to perform a histogram matching operation with the input images.

Input Images

Input Peaks (Band 1) image

Input image for histmatch

Input Peaks (Band 1) image

Parameter Name: FROM

This is the input image for the histmatch example.

Input Peaks (Band 1) image

Band 1 histogram

Input Peaks (Band 1) image

This is the input image's histogram.

Input Peaks (Band 6) image

Match image for histmatch

Input Peaks (Band 6) image

Parameter Name: MATCH

This is the match image for the histmatch example (i.e. the other input's histogram will be matched to this image's histogram).

Input Peaks (Band 6) image

Band 6 histogram

Input Peaks (Band 6) image

This is the input image's histogram.

Output Images

Output image showing results of the CDF histogram matching.

Output image for CDF matching

Output image showing results of the CDF histogram matching.

Parameter Name: TO

This is the output image that results.

Output image

CDF histogram

Output image

This is the output image's histogram.

Example 2

Peaks histogram matching with mode

This example shows the results of histogram matching using the match mode function.

Command Line

Use mode matching to adjust Band 1's histogram to resemble Band 6's histogram
histmatch from=../peaks.cub+1 match=../peaks.cub+6 stretch=mode to=../result.cub

Input Images

Input Peaks (Band 1) image

Input image for histmatch

Input Peaks (Band 1) image

Parameter Name: FROM

This is the input image for the histmatch example.

Input Peaks (Band 1) image

Band 1 histogram

Input Peaks (Band 1) image

This is the input image's histogram.

Input Peaks (Band 6) image

Match image for histmatch

Input Peaks (Band 6) image

Parameter Name: MATCH

This is the match image for the histmatch example (i.e. the other input's histogram will be matched to this image's histogram).

Input Peaks (Band 6) image

Band 6 histogram

Input Peaks (Band 6) image

This is the input image's histogram.

Output Images

Output image showing results of the modal histogram matching.

Output image for mode matching

Output image showing results of the modal histogram matching.

Parameter Name: TO

This is the output image that results.

Output image

Mode histogram

Output image

This is the output image's histogram.