histeq
Apply histogram equalization to a cube.
This program equalizes the histogram of an input cube (defined by FROM), and outputs the results to a file (defined by TO).
By equalizing the input file's histogram, the resulting cumulative distribution becomes linear instead of curved. The following is an illustration of what happens to an input file. The blue line represents the histogram and the red line is the cumulative distribution. On the left is the histogram and cumulative distribution of an unmodified image, while the figure on the right shows how the both the histogram and distribution are altered.
The blue line represents the input file's histogram and the red line represents its cumulative distribution function.
By equalizing the input file's histogram, the resulting cumulative distribution becomes linear instead of curved. The following is an illustration of what happens to an input file. The blue line represents the histogram and the red line is the cumulative distribution. On the left is the histogram and cumulative distribution of an unmodified image, while the figure on the right shows how the both the histogram and distribution are altered.
The blue line represents the input file's histogram and the red line represents its cumulative distribution function.
Categories
Related Objects and Documents
Applications
History
| Sean Crosby | 2006-12-15 | Original version |
| Steven Lambright | 2008-05-06 | Histogram object no longer has SetRange, updated to use SetValidRange |
| Steven Lambright | 2008-05-13 | Removed references to CubeInfo |
| Tyler Wilson | 2015-09-03 | Commented out a call to Histogram::SetValidRange(min,max) Because of changes made to the Histogram class. See Ref. #2188. |
Parameters
Files
This file will have its cumulative distribution reshaped to be more linear.
| Type | cube |
|---|---|
| File Mode | input |
| Filter | *.cub |
The resultant cube containing a linearized image
| Type | cube |
|---|---|
| File Mode | output |
| Filter | *.cub |
Histogram Options
Minimum DN cut-off value at the cumulative percent of the histogram
| Type | double |
|---|---|
| Default | 0.5 |
| Minimum | 0.0 (inclusive) |
| Less Than | MAXPER |
Maximum DN cut-off value at the cumulative percent of 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
Histogram equalization
This example shows the results of histogram equalization on a single band of an image.
Command Line
Use histogram equalization to the make the input cube's sixth band distribution function linear.
histeq
from=../peaks.cub+6 to=../result.cub
GUI Screenshot
Example Gui
Histeq GuiScreenshot of GUI with parameters filled in to perform a histogram equalization operation with the input image.
Input Images
Input image for histeq
Input Peaks (band 6) Image
Parameter Name:
FROM
This is band 6 of the input image for this example.
Band 6 histogram
Input Peaks (band 6) ImageThis is the input image's cumulative distribution for band 6.
Output Images
Output image for histogram equalization
Output image showing the result of the histogram equalization.
Parameter Name:
TO
This is the output image that results.
Resulting cumulative distribution
Output imageThis is the output image's cumulative distribution.