Zonal Histogram changes values

Discussion created by sascher1 on Apr 9, 2014
Latest reply on Apr 15, 2014 by sascher1

i did some investigations on photogrammetry and wanted to creat a zonal histogram on grayscale values. Thus, I have to raster datasets; one is my classification raster (8 classes) and one is the original grayscale image raster. Both are absolutely identical in their geometry.
The lowermost grayvalue of the original image is 52.something. When I calculate the zonal histogram values down to 0 occure in both histogram and table. Maximum value stays at 255.
So, either the count per class (zone) is not related to the grayscale values or something is completely wrong.

Any ideas?