Hi
Lossy compression should be okay, provided that the errors introduced are
smaller than those expected for counting statistics (assuming that the
pixels are more-or-less independent) - i.e. less than the square-root of
the individual pixel intensities (though I don't see why this can't be
extended to the integrated reflection intensities). So it's more important
to accurately retain your weak pixel values than your strong ones - an
error of ±10 for a pixel in a background count where the background should
be 40 is significant, but an error of ±10 for a saturated pixel on most
detectors (say, about 64K for a CCD) wouldn't affect anything.
On the question of lossy compression, I think we'd have to ask some data
reduction guru's how much the "noise" would affect the data reduction. I
suspect that the main problem is that the noise added would be
correlated across the image and would therefore affect the background
statistics in a non-trivial way. Although the intensity measurements may
not be badly affected the error estimates on them could be...
Harry
--
Dr Harry Powell, MRC Laboratory of Molecular Biology, MRC Centre, Hills
Road, Cambridge, CB2 2QH
