[ROOT] Re: Data from CCDs

From: Florian Schopper (fls@ipp.mpg.de)
Date: Tue May 15 2001 - 09:42:32 MEST


Hello Mr. Brun,

a frame is the matrix (rows x columns) of adc-values (about 12 bit) which 
stems from one readout cycle of the CCD. 
In principle, an array of TH2S`s is sufficient to hold the data,
but if people here want to look into time variations of e.g. of single 
column, a 3-dim dataarray seems more natural. 

They are used to an IDL-style like:
signal = float( , , ) 
plot, signal( 3 , 5:10 , 98:150 )
Which would give them     row 3 , col 5 to 10 , framenumber 98 to 150.

If I would have a list of 2D-Hists, I would have to copy some entries of
each into a new projection. I can write a class to hide that, but 
probably these things have all been done before.

Would a list of TH2`s store (and need memory for) a lot of redundant 
information besides the data ?

Florian Schopper 

> Hi Florian, Could you clarify what you mean by "Frame"  >From your brief
> explanation, I do not see why a TH2S histogram is not sufficient. The
> histogram number being the framenumber, row, col obvious and the adc the
> content (a short sufficient?) In case you intend to make statistical
> calculations using zillions of frames, a TTree would seem to be the most
> appropriate storage.  

> Rene Brun
               





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Florian Schopper                     office: MPI Halbleiterlabor

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