prevent automatic bit-depth promotion?

Discussion created by brokev03 on Aug 13, 2013
Latest reply on Aug 13, 2013 by MKennedy-esristaff
I have 2 rasters:

1) 2-bit .tif with 3 as the NoData value.  Only needs to express 0,1,NoData
2) 1-bit .tif with 0 as the NoData value. Only needs to express 1,NoData

No matter what sort of analysis I perform on these, they are always promoted to 8-bit with a noData value of 255. This is unacceptable because the file size balloons to 7gb with the promotion.  I have found no solution to ensure bit depth is preserved. Having to use copy raster between every operation is not an option. I don't understand why this is happening, because I am not introducing any new values into the rasters through analysis.

Any ideas?