Shouldn't you also flip the sign bit?
That's part of the traditional trick.

- Arnold

Steve Allen wrote:
...
Our data originate via a 16-bit AtoD conversion which produces bits
corresponding to C "unsigned short" on modern big-endian processors.
The pixel values are always offset such that all values are positive.
We store the bits directly in the image arrays as unsigned short
integers using the traditional trick of offsetting the physical data
values using the keywords

BITPIX = 16
BZERO = 32768
BSCALE = 1
...

--
Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064
Voice: +1 831 459 3046 http://www.ucolick.org/~sla
PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E 49 89 0E FE 26 B4 14 93

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Arnold H. Rots Chandra X-ray Science Center
Smithsonian Astrophysical Observatory tel: +1 617 496 7701
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