Le 08/11/2011 20:46, [log in to unmask] a écrit :
> Hmmm, so you would, when collecting large data images, say 4 images,
> 100MB in size, per second, in the middle of the night, from home, reject
> seeing compressed images on your data collection software, while the
> "real thing" is lingering behind somewhere, to be downloaded and stored
> later? As opposed to not seeing the images (because your home internet
> access cannot keep up) and only inspecting 1 in a 100 images to see
> progress?
>
1. I don't need to *see* all images to verify whether the collection is
going all right. If I collect remotely, I process remotely, no need to
transfer images. Data is collected so fast today that you may, even
while collecting at the synchrotron, finish the collection without a)
seeing actually all the images (cf. Pilatus detectors) b) keeping in
pace at all your data processing. The crystal died or was not collected
properly? You try to understand why, you recollect it if possible or you
try a new crystal. It's been always like this, it's call trial and error.
2. The ESRF in Grenoble produces thumbnails of the images. If all you
want to see is whether there is diffraction, they are good enough and
they are useful. They are extremely lossy and useless for anything else.
3. Please, compare contemporary facts. Today's bandwidth is what it is,
today's images are *not* 100 Mb (yet). When they get there, let us know
what is the bandwidth.
> I think there are instances where compressed (lossy or not) images will
> be invaluable. I know the above situation was not the context, but
> (y'all may gasp about this) I still have some friends (in the US) who
> live so far out in the wilderness that only dial-up internet is
> available. That while synchrotrons and the detectors used get better all
> the time, which means more MB/s produced.
I would understand a situation like the one you describe for a poor, or
an embargoed country where unfortunately there is no other way to
connect to a synchrotron. Still, that should be solved by the community
in a different way: by gracious cooperation with our colleagues in those
countries. Your example is actually quite upsetting, given the current
state of affairs in the world.
>
> James has already said (and I agree) that the original images (with all
> information) should not necessarily be thrown away. Perhaps a better
> question would be "which would you use for what purpose", since I am
> convinced that compressed images are useful.
>
I think I was clear: as long as we have access to the original data, I
don't care. I would only use the original data.
> I would want to process the "real thing", unless I have been shown by
> scientific evidence that the compressed thing works equally well. It
> seems reasonable to assume that such evidence can be acquired and/or
> that we can be shown by evidence what we gain and lose by
> lossy-compressed images. Key might be to be able to choose the best
> thing for your particular application/case/location etc.
>
This still assumes that future software will not be able to detect the
differences that you cannot see today. This may or may not be true, the
consequences may or may not be important. But there is, I think,
reasonable doubt on both questions.
> So yes, James, of course this is useful and not a waste of time.
>
I have said to James, off the list, that he should go on if he's
convinced about the usefulness of his approach. For a very scientific
reason: I could be wrong. Yet, if need be to go into the compression
path, I think we should prefer lossless options.
Best regards,
--
Miguel
Architecture et Fonction des Macromolécules Biologiques (UMR6098)
CNRS, Universités d'Aix-Marseille I & II
Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France
Tel: +33(0) 491 82 55 93
Fax: +33(0) 491 26 67 20
mailto:[log in to unmask]
http://www.afmb.univ-mrs.fr/Miguel-Ortiz-Lombardia
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