ISIS Application Documentation
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Apply a minimum or maximum filter to a cube
Description
Categories
Groups
Examples
History
Description
V1 V2 V3
V4 V5 V6
V7 V8 V9
the program will first substitute an extremely high or low internal value for ISIS.
This essentially zeroes out the process in such a way that one of the values in the
current boxcar will be supplied as the output pixel, instead of an output pixel from
a previous boxcar. Assume that the MAX option is being used on the model boxcar shown
above.This value is then compared to the first pixel in the boxcar. This would be
the value substituted for "V1". If V1 is greater than the internal value (this will
be the case unless V1 is a special pixel) then the new output pixel will tenatively
be set to V1. V1 is then compared to V2, and the greater pixel is again set to the
temporary maximum. This process continues until the temporary maximum is compared to
all of the values in the boxcar, at which point it is set as the output value.
Categories
Parameter Groups
Files
| Name | Description |
|---|---|
| FROM | Input cube |
| TO | Output cube |
Boxcar Size
| Name | Description |
|---|---|
| LINES | Boxcar Lines |
| SAMPLES | Boxcar Samples |
Filter Type
| Name | Description |
|---|---|
| FILTER | Type of filter (minimum, maximum) |
Files: FROM
Description
Use this parameter to select the filename. All bands within the file will have the filter applied.
| Type | cube |
|---|---|
| File Mode | input |
| Filter | *.cub |
Files: TO
Description
This file will contain the filtered output.
| Type | cube |
|---|---|
| File Mode | output |
| Pixel Type | real |
Boxcar Size: LINES
Description
Use this parameter to select the number of lines in the boxcar. Higher values take longer, and intensify the results in the vertical direction. The default value is three.
| Type | integer |
|---|---|
| Default | 3 |
| Minimum | 1 (inclusive) |
Boxcar Size: SAMPLES
Description
Use this parameter to select the number of samples in the boxcar. Higher values take longer, and intensify the results in the horizontal direction. The default value is three.
| Type | integer |
|---|---|
| Default | 3 |
| Minimum | 1 (inclusive) |
Filter Type: FILTER
Description
Use this parameter to choose the filter type. The possibilities include min, which finds the lowest DN in the boxcar and max, which finds the highest DN in the boxcar.
| Type | string | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Default | MIN | |||||||||
| Option List: |
|
Examples
Example 1
Minimum 3x3
Description
Command Line
GUI Screenshot
minmax gui
|
Example GUI Screenshot of the GUI with parameters set to perform the minimum filter with a 3 x 3 boxcar. |
Input Image
The image before the filter
|
Input image before minmax.
Parameter Name:
FROM This is the image as it was taken originally. Take note of the size of areas with high DNs, such as on top of mountains and in the lower right corner of the image. |
Output Image
The image after the filter
|
Output image after minmax
Parameter Name:
TO The filtered image. A side-effect of the program is a slight blur to the image, but notice the change in the details described above. the mountain tops have lost some area, while the dark region at the base has expanded. Also note the reduced intensity of the brightness in the lower right corner. |
Example 2
Maximum 2x2
Description
Command Line
GUI Screenshot
minmax gui
|
Example GUI Screenshot of the GUI with parameters set to perform the maximum filter with a 2 x 2 boxcar. |
Input Image
|
The image before the filter
|
Input image before minmax.
Parameter Name:
FROM This is the image as it was taken originally. Take note of the size of areas with high DNs. In particular, notice the man-made lights in the lower right corner of the image and the bright spots on top of the mountain. |
Output Image
The image after the filter
|
Output image after minmax
Parameter Name:
TO The filtered image. Just as in example 1, the image is blurred slightly. Unlike the first example, bright areas are now enlarged and the brightness that would have been shrunk using the minimum filter is now expanded. Again, note the peaks of the mountains and the man-made lights in the lower right corner. |
History
| Drew Davidson | 2004-07-23 | Original version |
| Drew Davidson | 2004-07-26 | Added application test |
| Drew Davidson | 2004-08-16 | Added examples |