| 18 Jan 2014 12:30 AM |
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Hi to all. Please suggest me, regarding extracting the minimum DN value from the MODIS image by using ENVI 4.7 software. It was a stacked image of 12 layers. Here i want to extract minimum value per pixel.
Thank you,
M.Thirupathi
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Deleted User
New Member
Posts:59  
| 20 Jan 2014 11:10 AM |
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Hi,
Have you tried using the Statistics tool? From the menu bar, select Basic Tools > Statistics > Compute Statistics. Select the input file, and it will compute the min and max pixel values for each band/layer, along with other basic statistics.
-JasonW
Exelis VIS
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Deleted User
New Member
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| 03 Mar 2014 10:49 AM |
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if we do it ( compute statistic) how can we find max or min pixel location? Where is on the map max pixel?
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Berangere Casson
New Member
Posts:61
| 04 Mar 2014 06:18 AM |
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If you have an ENVI+IDL license you can identify the location of the minimum of your image using the WHERE routine:
location= WHERE(image eq MIN(image))
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Deleted User
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| 04 Mar 2014 08:15 AM |
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how can I do ? I have Envi with licence but I don't know Envi + IDL please help me, because this problem is very important for me
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Deleted User
New Member
Posts:59
| 04 Mar 2014 10:39 AM |
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Hi,
Unfortunately there is no tool in ENVI 4.7 that will identify the geographic location of pixels with the minimum DN value. However, the Density Slice tool may help you visually identify those pixels in an image:
1. Compute the basic statistics on your stacked image and note the minimum data value(s).
2. From the display group menu bar, select Tools > Color Mapping > Density Slice.
3. In the Density Slice dialog, delete all the ranges except for one.
4. Select the remaining range, and click Edit Range.
5. Enter the same value (the minimum DN value) in both the Range Min and Range Max fields. Select a color that will highlight those pixels.
6. Click Apply. If you do not see the pixels of interest, you may need to adjust the Range Max field until you can begin to see the pixels with the lowest values.
7. Use the Cursor Location/Value tool to identify the geographic coordinates of the pixels that are highlighted (those with a minimum DN value).
I hope this helps.
-jw
Exelis Visual Information Solutions
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Deleted User
New Member
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| 04 Mar 2014 02:07 PM |
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how can we use where routine in ENVI 5+IDL can you describe for us please???
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Deleted User
New Member
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| 14 Mar 2014 07:08 AM |
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I may not have understood the original question correctly, but it sounds like you want an array of minimums derived from the band axis. i.e. img is a 3x3x12 array, and you want to find the minimum value for each pixel in the 3x3 across the 12 band dimension axis. If you have IDL then simply call mn = min(img, dimension=3). The result will be a 3x3 array containing the minimum value for each x,y pixel across the 12 bands. But that all depends upon having an IDL licence.
Josh
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