# Can some one explain how standard deviation is calculated for a multiband image?

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09-20-2013 04:07 AM
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New Contributor
Hi all,

I have been working with multiband images and on calculating standard deviation I am not sure what happens ? So can some one explain how standard deviation is calculated for a multiband image? Usually its a single band operation so how is it dealt with in ARC GIS?

Thanks and Regards
Samee
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Esri Esteemed Contributor
Hi all,

I have been working with multiband images and on calculating standard deviation I am not sure what happens ? So can some one explain how standard deviation is calculated for a multiband image? Usually its a single band operation so how is it dealt with in ARC GIS?

Thanks and Regards
Samee

Hi Samee,

Not sure which aspect you refer to, so I�??ll try to tackle a few.

Visualization of multispectral raster data
When you display a multispectral image you have the possibility to stretch the bands before the Red, Green and Blue components are combined to  a color. One of the stretch methods is �??Standard deviation�?�. In this case it is calculated per band for all cells. More info here:
http://resources.arcgis.com/en/help/main/10.2/index.html#//009t00000059000000

If you look at the explanation in the �??Raster data statistics�?� you�??ll see that:
"Statistics are calculated for each band; if there is more than one band in the raster dataset, the statistics for each band are present. You can see that the parameters used to build the statistics are listed. The statistics that are calculated include the minimum and maximum pixel values as well as the mean and standard deviation of the calculated pixel values�?�". More info here:
http://resources.arcgis.com/en/help/main/10.2/index.html#//009t0000001s000000

Statistics (raster) functions
There is also the possibility to make use of focal statistics functions (on a single band data). In this case a �??virtual�?� new raster is created where each cell value will be the result of a standard deviation in a 3x3 or 5x5 moving windows. More info here:
http://resources.arcgis.com/en/help/main/10.2/index.html#//009t00000058000000