Unusual rejection in MasterDark

[Jameedon]

I used the BatchPreProcessing Script to calibrate my light subs.  I used 400 Bias and 64 Dark subs to make Masters (WinSig clipping low=4 high=3), and flats were used also.  I noticed an unusual pattern seen in the High Rejection Map that opens with the MasterDark, where a lot more pixels were rejected in and around the center of the frame (it kinda looks like the Chevy logo).  I didn't think much of it because the MasterDark looked ok, and it didn't have a Chevy logo of missing pixels in the center, so I went on with finishing the preprocessing.

When I had the MasterLight I started working on it (Crop, DBE, BN, CC and TGVD), but now I'm noticing that there is a darker spot in the center shaped like a Chevy logo.  I'll include a screenshot of the MasterDark High Rejection Map that I adjusted the sliders on to make the center more visible.  I will also post links to the actual MasterDark/Reject Maps and a single Dark sub used to make the Master.  As far as I can tell, the single dark sub doesn't have the Chevy logo.

What can I do to prevent those center pixels from being rejected in the MasterDark?  Different clipping algorithm?

And I guess I should ask if anyone else sees this Chevy logo with their Canon DSLR?  Mine is a full spec 650D.

MasterDark
https://www.dropbox.com/s/34atrjbgnc5jqog/MasterDarkBPP_300s_iso800_23c26c.xisf?dl=0

Single dark sub
https://www.dropbox.com/s/yjusv0hk2lzghwx/__Dark_300sec_ISO800_26.0C__None_2016-10-01_081739_frame10.CR2?dl=0

[MikeOates]

Jamee,

If you get anything other than random noise, or satellite trails etc. in your master dark you may have accidentally included a sub that is not a dark frame in your integration.

So I would examine all the Darks and Bias frames to make sure. Use Blink for this.

Mike

[pfile]

this seems relevant... that camera has special focusing pixels. same pattern shown here:

https://www.magiclantern.fm/forum/index.php?topic=16054.25

not sure what the solution is, though.

rob