Hi Piotr,
using your sample file, I was able to reproduce the problem
you described. It is caused by a bug in version 1.0.5 of the
IlmImf library and a corresponding fix in version 1.0.7:
Attempting to compress sufficiently random pixel data will
expand rather than shrink the data. When this happens the
pixels are stored in the file in uncompressed form.
In version 1.0.5 it is possible that the InputFile and
OutputFile classes disagree about whether the data in the
file are actually compressed or not. Consequently the file
may be decoded incorrectly. This bug was fixed in version
1.0.7. However, the fix did apparently introduce the
possibility that uncompressed pixel data saved in a file
by 1.0.5 version of class OutputFile can be read by version
1.0.5 of class InputFile, but not by version 1.0.7 or later.
Unfortunately, there is no reliable way to detect files
where this situation occurs.
I recommend that you upgrade all of your applications to
version 1.0.7 or later. If you can, upgrade to 1.2.2.
Florian