topic Re: Zonal histogram seems to be stretching values in ArcGIS Spatial Analyst Questions

Zonal histogram seems to be stretching values

PriyamvadaTrivedi — Thu, 07 Mar 2013 08:51:38 GMT

The values of pixels in the original raster range from 0-63. However when I make a histogram (Zonal Histogram), using a shapefile as my input zones, I get a distribution of values from 0-255. Any idea how this is happening? How can I ensure that the values are from 0-63?

Any help would be appreciated.

Thank you.

Re: Zonal histogram seems to be stretching values

EricRice — Thu, 07 Mar 2013 14:57:09 GMT

You're probably displaying the raster with a stretched renderer. Switch it to unique values then run Zonal Histogram.

Usage Tip from tool documentation that I believe applies here:

"In the histogram graph, the number of classes (bins) for each zone is determined by the Input value raster.

If a layer is specified, then the layer's symbology defines the number of classes.

If a dataset is specified, by default there will be 256 classes, unless the input is integer with less than 26 unique values, in which case it will be the total count of unique values."

The graph is based on the table, so maybe we need to reword that a little.

Best,
Eric

Re: Zonal histogram seems to be stretching values

GuilhermeBraghirolli — Mon, 23 Sep 2019 23:36:23 GMT

I had the same issue and this solution solved it.

Is there any way of doing this inside the model builder? It automatically generates the histogram from 0 to 255.