Author Topic: Help with ImageCalibration results  (Read 1599 times)

Offline rtemen

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Help with ImageCalibration results
« on: 2018 January 14 08:41:49 »
Hi, all.
I was wondering if I could get some guidance on my first step of processing my lights.
I have a before and after file in my dropbox.
https://www.dropbox.com/sh/hm4vlra13ng6rto/AABWEv2wd7oA33E7Evbn-PB9a?dl=0

It looks to my untrained eye that the before is nicer and cleaner than the after.
Here I used my light with my MasterSuperBias, MasterDark and MasterFlat.
Is the after supposed to look like this, or is there something wrong with my Masters?

Thanks.

Online Greg Schwimer

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Re: Help with ImageCalibration results
« Reply #1 on: 2018 January 14 09:04:22 »
Are these from a color camera? The before image appears to have a bayer matrix. You can see this as a checkerboard pattern when you zoom into the pixel level. The after image does not have this, but is still grayscale.
- Greg
Scottsdale, Arizona, USA

Offline rtemen

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Re: Help with ImageCalibration results
« Reply #2 on: 2018 January 14 10:41:47 »
Yes, it is a color camera. 
Canon T3i (600D)
When I start PI, I first select pure raw first.

I am in Cave Creek.  Would you be open to talking?

Rich

Offline bulrichl

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Re: Help with ImageCalibration results
« Reply #3 on: 2018 January 14 10:53:34 »
Hi Rich,

1) Both the uncalibrated and the calibrated light frame are monochrome, not debayered images from a Canon T3i.

2) The flat frame correction seems to be OK. You can check that by debayering both images (RGGB, VNG). The calibrated image seems to be flat. However it contains all of the hot pixels that are in the uncalibrated image. So I conclude that the calibration with the MasterDark went wrong.

3) The FITS header of the calibrated frame tells us that you used the following setting für the light frame calibration:

----------------------
MasterBias: enabled
Calibrate: not enabled

MasterDark: enabled
Calibrate: not enabled
Optimize: enabled (scaling factor 0.388)

MasterFlat: enabled
Calibrate: not enabled
----------------------


However, I don't understand the settings in the Master Dark section.

Did you pre-calibrate your MasterDark with the MasterBias (SuperBias)?

If the answer is YES: you never should do that, see https://pixinsight.com/forum/index.php?topic=11968.0
Use the NOT pre-calibrated MasterDark and enable 'Calibrate' in the MasterDark section.

If the answer is NO: you have to enable 'Calibrate' if you use 'Optimize'.


I am not sure whether this will solve all of the problems. Please try what I recommended and post the result.

Bernd

Online Greg Schwimer

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Re: Help with ImageCalibration results
« Reply #4 on: 2018 January 14 14:39:04 »

I am in Cave Creek.  Would you be open to talking?

Sure. PM me.
- Greg
Scottsdale, Arizona, USA

Online Greg Schwimer

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Re: Help with ImageCalibration results
« Reply #5 on: 2018 January 14 15:27:14 »
Correction to my prior statement. The bayer matrix is tough to see in "after", but it does debayer. I ran BackgroundNeutralization, ColorCalibration, and SCNR all at defaults against the "after" image and it looks OK. Comparing to the "before" image after running the same processes on it, the "after" version looks like it has been flat corrected. The background signal is significantly lower, but this could be a result of removing dark and bias signal.

I see a few hot pixels in the mix. CosmeticCorrection may clean this up for you.

Have you tried integrating these?

What are the details for these subs? How long? What telescope?

Here's a side-by-side. After is on the left.

- Greg
Scottsdale, Arizona, USA

Offline bulrichl

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Re: Help with ImageCalibration results
« Reply #6 on: 2018 January 14 16:03:14 »

What are the details for these subs? How long? What telescope?
From the FITS header: ISO 800, 180 s. Estimated focal length: 1000 mm.

Bernd