Bug: Raster pixel query value is different than expected for ArcMap Server on UNIX
Raster pixel values returned for a GET_RASTER_INFO request may be different than the expected values, or the values returned by ArcMap, for the following raster formats:
CADRG, CIB, Erdas Imagine, GeoTIFF, MrSID and TIFF (multiband)
This is a known limitation.
There are currently no workarounds for this issue.