[ome-users] Why is the original image data

[Ilya Goldberg]

Basically, what Mike said.
I would add that we have taken some steps to mitigate the additional 
space usage:
1.  Image data is compressed unless its actively used (both the 
original data and the OME Format pixels).  In "real life" scenarios, 
this results in a recovery of 1/2 to 2/3 of disk space.  That's disk 
space assuming no OMEIS at all.  In other words, using OMEIS with its 
duplication of pixels uses 1/2 - 1/3 of the disk space compared to 
storing just the original data without OMEIS (and without compression). 
  Images are compressed after 30-90 days depending on settings, so this 
is over a significant time frame (many months).
2.  The pixels in "OME Format" (i.e. not "original data") are basically 
a cache.  Also depending on settings, they get purged so that the 
"original data" is really the only repository of the pixels.  This only 
applies to cases where the OME Format pixels *are* the original pixels. 
  If you have pixels that are derived (from analysis), then they are the 
original pixels, and will therefore never be purged unless you delete 
the MEXes that created them.

Both of these things are completely transparent to the user, except 
that a delay will be incurred when inflating pixels or recovering from 
a "cache miss".

So in short, its not as bad as it initially seems, and in reality its 
often a lot better than what people have presently.

-Ilya

On Sep 14, 2005, at 12:46 PM, gerhard wrote:

> Can anyone tell me why the original image data is also stored on OMEIS.
> regarding the space images need, does it make sense?
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