ISIS Application Documentation
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Apply lowpass or blurring filter to a cube
Description
Categories
Groups
Examples
History
Description
Categories
Related Applications to Previous Versions of ISIS
This program replaces the following application existing in previous versions of ISIS:- boxfilter
Related Objects and Documents
Applications
Parameter Groups
Files
| Name | Description |
|---|---|
| FROM | Input file |
| TO | Output lowpass cube |
Boxcar Size
| Name | Description |
|---|---|
| SAMPLES | Number of samples in boxcar |
| LINES | Number of lines in boxcar |
Boxcar Settings
| Name | Description |
|---|---|
| LOW | Minimum valid DN |
| HIGH | Maximum valid DN |
| MINOPT | Sets minimum to be either a count or a percentage |
| MINIMUM | Minimum boxcar pixels required for filter |
| REPLACEMENT | Replacement if minimum not met |
Non-Special Pixel Filtering
| Name | Description |
|---|---|
| FILTER | Which pixels to filter |
Special Pixel Filtering
| Name | Description |
|---|---|
| NULL | Filter NULL Pixels |
| HRS | Filter HRS Pixels |
| HIS | Filter HIS Pixels |
| LRS | Filter LRS Pixels |
| LIS | Filter LIS Pixels |
Files: FROM
Description
Input cube to filter
| Type | cube |
|---|---|
| File Mode | input |
| Filter | *.cub |
Files: TO
Description
The resultant filtered cube
| Type | cube |
|---|---|
| File Mode | output |
Boxcar Size: SAMPLES
Description
This is the total number of samples in the boxcar. It must be odd and can not exceed twice the number of samples in the cube. In general, the size of the boxcar does not cause the program to operate significantly slower.
| Type | integer |
|---|---|
| Minimum | 1 (inclusive) |
| Odd | This value must be an odd number |
Boxcar Size: LINES
Description
This is the total number of lines in the boxcar. It must be odd and can not exceed twice the number of lines in the cube. In general, the size of the boxcar does not cause the program to operate significantly slower.
| Type | integer |
|---|---|
| Minimum | 1 (inclusive) |
| Odd | This value must be an odd number |
Boxcar Settings: LOW
Description
Valid minimum pixel value that will be used in boxcar computation. If a pixel value is less than LOW then it will not be used when computing the average.
| Type | double |
|---|---|
| Internal Default | Use all pixels |
| Less Than |
|
Boxcar Settings: HIGH
Description
Valid maximum pixel value that will be used in boxcar computation. If a pixel value is greater than HIGH then it will not be used when computing the average.
| Type | double |
|---|---|
| Internal Default | Use all pixels |
| Greater Than |
|
Boxcar Settings: MINOPT
Description
This parameter determines whether the minimum parameter is to be interpreted as a count of pixels, or a percentage of all pixels in the boxcar.
| Type | string | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Default | COUNT | |||||||||
| Option List: |
|
Boxcar Settings: MINIMUM
Description
This option is the minimum number of valid pixels required in a boxcar for filtering to begin.
| Type | double |
|---|---|
| Default | 1 |
Boxcar Settings: REPLACEMENT
Description
This determines what to put in the center pixel, in the event that there aren't enough valid, non-special pixels in the boxcar to meet the minimum. The default is to replace it with the current value, and the other option is to replace it with NULL.
| Type | string | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Default | CENTER | |||||||||
| Option List: |
|
Non-Special Pixel Filtering: FILTER
Description
These options choose which pixels to filter. The options are ALL, VALID and INVALID. If the first is chosen, the filter will be run on all pixels inside the LOW-HIGH range, and all Specials declared valid. If the second option is chosen, the filter is only run when the center pixel is valid, and the third option only runs the filter when the center is invalid. Regardless of which option is chosen, the average is only calculated from values between LOW and HIGH.
| Type | string | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Default | ALL | ||||||||||||
| Option List: |
|
Special Pixel Filtering: NULL
Description
If the center pixel of a boxcar is NULL, and this box is checked, the pixel will be overwritten with the average value of the boxcar as a whole. If this box is not checked, the pixel will be left alone.
| Type | boolean |
|---|---|
| Default | TRUE |
Special Pixel Filtering: HRS
Description
If the center pixel of a boxcar is HRS, and this box is checked, the pixel will be overwritten with the average value of the boxcar as a whole. If this box is not checked, the pixel will be treated according to the REPLACEMENT parameter.
| Type | boolean |
|---|---|
| Default | TRUE |
Special Pixel Filtering: HIS
Description
If the center pixel of a boxcar is HIS, and this box is checked, the pixel will be overwritten with the average value of the boxcar as a whole. If this box is not checked, the pixel will be treated according to the REPLACEMENT parameter.
| Type | boolean |
|---|---|
| Default | TRUE |
Special Pixel Filtering: LRS
Description
If the center pixel of a boxcar is LRS, and this box is checked, the pixel will be overwritten with the average value of the boxcar as a whole. If this box is not checked, the pixel will be treated according to the REPLACEMENT parameter.
| Type | boolean |
|---|---|
| Default | TRUE |
Special Pixel Filtering: LIS
Description
If the center pixel of a boxcar is LIS, and this box is checked, the pixel will be overwritten with the average value of the boxcar as a whole. If this box is not checked, the pixel will treated according to the REPLACEMENT parameter.
| Type | boolean |
|---|---|
| Default | TRUE |
Examples
Example 1
Running a 3x3 boxcar on all pixels
Description
Command Line
GUI Screenshot
lowpass gui
|
Example GUI Screenshot of the GUI set to filter all pixels for the image using a three by three boxcar. Note that as many of the default parameters as are allowed are being used. |
Input Image
The image before the filter
|
Input image before the lowpass filter.
Parameter Name:
FROM Here we see the original cube. The areas of greatest interest are those with a great deal of contrast such as edges. |
Output Image
The image after the filter
|
Output image after lowpass
Parameter Name:
TO After the filter, the entire image is somewhat softer. The difference may be hard to detect on uniform areas, but the sections of the image that previously were sharply contrasted are now blurred. As this particular configuration has been set for a small filter, the results are obtained quickly and are more subtle than a large filter. |
Example 2
Running a 21x21 boxcar on all pixels
Description
Command Line
GUI Screenshot
lowpass gui
|
Example GUI Screenshot of the GUI set to filter all pixels for the image using a 21 by 21 boxcar. This configuration will be slightly slower than in the previous example, due to the increased boxcar size. |
Input Image
|
The image before the filter
|
Input image before the lowpass filter.
Parameter Name:
FROM Here we see the original cube. The areas of greatest interest are those with a great deal of contrast such as edges. |
Output Image
The image after the filter
|
Output image after lowpass
Parameter Name:
TO As seen here, the 21 by 21 boxcar blurs the image to a great extent. In fact, there seems to be little purpose for ever using a square boxcar this large, except for the purpose of illustrating the effect of the lowpass. |
History
| Eric Eliason | 1988-05-20 | Original version |
| Jeff Anderson | 2002-07-10 | Ported to Isis 3.0 |
| Kim Sides | 2003-05-13 | Added application test |
| Stuart Sides | 2003-05-16 | Modified schema location from astogeology... to isis.astrogeology..." |
| Stuart Sides | 2003-07-29 | Modified filename parameters to be cube parameters where necessary |
| Drew Davidson | 2005-08-17 | Added examples |
| Brendan George | 2005-11-21 | Modified user interface |
| Elizabeth Miller | 2005-11-22 | Fixed appTest parameters and documentation |
| Brendan George | 2006-05-31 | Added Minopt parameter, modified user interface |
| Brendan George | 2006-06-19 | Reorganized user interface |