Cant integrate bias files

[jamesRC]

I am new. I am trying to make a master bias file via ImageIntegration and it always stops instantly with the message:

*** Error: L:/astronomy working 1/9_26_14 andromeda/BIAS from pinwheel/tif/SeriesB1-2_001.tif: Zero or insignificant signal detected (empty image?)
<* failed *>

These files have stuff in them! I have also tried this with the usual fits files, and they also fail. I apologize if this is not a new problem. I have read somewhat in this forum about this error message, the consensus was that there was something wrong with the files to make them appear empty. However they are not empty!

I could use a little help tracking down the cause of this problem, as my progress in PI has stopped here, right at the beginning

Thank you!

[RickS]

What do the bias frames look like if you open a few and give them a screen auto stretch? (Ctrl-A on Windows.)  Also try running the Statistics process to get an idea what the data values look like.

Cheers,
Rick.

[jamesRC]

Hello Rick, thanks for your response. FWIW these bias files are grey channel fits files.
The appearance is a very rough texture. I wasn't happy to see they also have mottling, uneven illumination.
This is bad but shouldn't cause them to abort the process, right?

Afraid I'm too beginner-ish to understand the statistics results.
The values I get from an example bias file are:

count (%):      100.00000
count(px):      16389120
mean:      203.9
median:      16.0
avgDev:      235.5
MAD:      0.0
minimum:      16.0
maximum:      21344.0

Like I said there's SOMEthing in those files :-)

James

[RickS]

Hi James,

Yes, you do have some signal.  The stats look a little odd compared to bias frames I've seen before but I guess that's possible (in particular the mean and median aren't usually that different).

I presume you have appropriate ImageIntegration settings for creating a master bias?  Back in the days before BatchPreprocessing here's what I used:

Combination: Average
Normalization: No normalization
Weights: Don't care
Evaluate noise: false
Use file cache: false
Rejection algorithm: Winsorized Sigma clipping
Rejection normalization: No normalization
Sigma low: 4
Sigma high: 3

If you have noise evaluation turned on that might be causing your error.

Cheers,
Rick.

[bulrichl]

Hi James,

in order to give helpful advice one needs more information about your bias files.

What camera are you using?

You say that the "bias files are grey channel fits files", but ImageIntegration tells us they have TIFF format. Which software is used for image acquisition? If the fits files were converted to TIFF: which software was used for this conversion?

Bernd

[jamesRC]

RickS:

Thank you! Your settings allowed aa successful bias file integration. Such little things, very demanding.

bulrichl:

TI have been attempting ImageIntegration using both original fits files, and tiffs made with ImageJ. My reference was to some tiff files, sorry about that confusion. I have been successful with richS' suggested settings, but I'll answer your questions too. I use AstroPhotography Tool for image acqusition.  My camera is a ZWO ASI1600MM COOL at 3 degrees F.

hope this is useful info!

James