[Nexus] pixel_mask documentation

Michael Rissi michael.rissi at dectris.com
Wed Jul 10 06:48:41 BST 2013

Hey Tobias,

We intend also to mark the invalid pixels in the images themselves with -1.
So only if you want to know what is wrong with a marked pixel, you can
check the pixel mask.

Is 6 or 7 targeted for corner pixels on Eiger/Pilatus?

7 is for corner pixels. Bit 6 is for pixels that lie in a cluster of bad

> To make it easy for consuming software I would not want any bits to be set
> for a usable pixel value. 95% would not care about a reason for not using
> the pixel. Flagging up these special pixels somewhere is useful but maybe
> not in a "mask". Maybe I am wrong anyway.
> What's "5 non uniform" exactly?  Just that I can make the documentation
> most meaningful.

I am sorry, that was still there for historical reasons... We can remove
this flag, as we do not really need it anymore.

> Bits do come in handy though. It allows us to add:
> 8 user specified
For pixels that are masked out by the user although they have a physically
> "correct" reading but for example represent artefacts in the measurement
> like beamstops. Agreed?

Yes, definitely!

Best regards,
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