New tutorial: Master Calibration Frames: Acquisition and Processing

[Hans Pleijsier]

Vicent,

Thank you for the calibration tutorial.
Unfortunately, sofar I was unable to integrate my canon cr2 raw darks into a masterdark because it is impossible to select cr2-files in the image integration process window. The monster seems to eat fits files only.

Any guidance on this?

Hans Pleijsier

[NKV]

Unfortunately, sofar I was unable to integrate my canon cr2 raw darks into a masterdark because it is impossible to select cr2-files in the image integration process window. The monster seems to eat fits files only.

Any guidance on this?

BatchFormatConversion 

[harist]

Sander, I was indeed subtracting bias twice since MasterDark is not bias subtracted. So I tried various combinations and the bottom line is that when I calibrate ONLY with darks then no info is lost. If I use MasterFlat and MasterDark, or MasterBias and MasterFlat or any of these two alone, then info is gone. There is something definetly wrong with the MasterBias (I will check the process again, maybe I did something stupid). Debayering is OK (I switched to bilinear).

Thanks,
Tasos

[Hans Pleijsier]

NKV,
batchformatconversion ....
thanks,  this might be a nice workaround but it's an extra step altogether.
HP

[Juan Conejero]

Unfortunately, sofar I was unable to integrate my canon cr2 raw darks into a masterdark because it is impossible to select cr2-files in the image integration process window.

Yes, this is a limitation of the current ImageIntegration process. ImageIntegration has been designed to work with incremental file reading operations, which are not possible with DSLR raw images.

This is the right procedure to work with DSLR raw images:

1. Open the Format Explorer window. Double click on the DSLR_RAW item (left column). On the RAW Format Preferences dialog, select the following set of options:

- Disable both white balance options.
- Enable the Create raw Bayer image option.
- Enable the No black point correction option.
- Click the OK button.

2. Use the BatchFormat conversion script to convert all your CR2 files into FITS files. Note that this is strictly necessary just for your calibration frames (dark, bias, flats), since ImageCalibration can load your CR2 files directly. However, I personally prefer to convert all raw DSLR images into FITS.

Now you can use the full set of PixInsight tools for calibration and integration. Note that step 1 is a one-time action, as the settings will be remembered across core application executions.

batchformatconversion ....
thanks,  this might be a nice workaround but it's an extra step altogether.

Indeed, but PixInsight's ImageCalibration and ImageIntegration tools are superior to other implementations. The BatchFormatConversion step is a small price to pay for ImageIntegration's performance.

[Juan Conejero]

To be honest if you have a windows box you're better of using DeepSkyStacker. If you want to stack in PI you could use DSS to create calibrated subs for you.

With the due respect to your opinion, I disagree. DSS is an excellent application, and I can only recommend using it. In my opinion, however, PixInsight's ImageCalibration, StarAlignment and ImageIntegration tools are superior on all platforms, including Windows.

[Harry page]

Hi Juan

I will agree that alignment and integration are beyond excellent , but I am going to have to put calibration in the " work in progress bracket " 

 Please listen to peoples concern on this matter as what should be a relatively simple application seems to be confusing  well to me anyway

I wait for you to show me the error of my ways 

Harry

[Hans Pleijsier]

Juan,
thank you and ... I will be most loyal to PI 
HP

[Juan Conejero]

Hi Harry,

I am going to have to put calibration in the " work in progress bracket "

Of course, I completely agree: ImageCalibration is a work in progress. Please see also my answer to other related post.

But, man, don't cry for that The whole PixInsight is a work in progress, always and (I hope) forever! Do you think ImageIntegration and StarAlignment are finished tools? Not at all!  

[Harry page]

Hi Juan

Yes , but some things are more finished than others 

Harry

[mmirot]

Well Harry you a me will just have to bang on the drum until our programs friends in this community write a few scripts  :

I am sure it available in PCL and Java Script.

I would be on it myself but my programming skill are non existent. 

Max

[Harry page]

Hi Max

I also have no programing skills to offer but can manage a beat or two on the bongo's     so a drumming we will go 


Harry

[harist]

StarAlignment and ImageIntegration tools are superior on all platforms, including Windows.

I quite agree with that, however I pinpointed my problem to the very peculiar fact that my raw 16 bit bias frames (0.001 exp. time), are interpreted by PI as having values in the range of 0.5 (32000 in the 16 bit scale), thus they eliminate all info from my light frames (except bright stars). Light frames and darks (60 sec exposures), are shown OK. I opened the bias frames in ImagePlus and Astroart and their pixel values are correct there. So PI is playing some tricks here that have nothing to do with the IC or Integration tool. If this is solved then calibration, debayering, alignment and stacking can all be performed by PI for OSC data.

Any suggestions?

Thanks
Tasos

[Harry page]

Hi Tasos

Just to make you feel better I also have this exact problem when I try and import stuff from AA4 I have not done the full monty in PI so do not know if this will sort it or not 
I have tried rescaling everthing and this does not work, I have told mr juan about this and await his comments

Harry

[Juan Conejero]

Hi Tasos and Harry,

At this point I'd need to take a look at your images before trying to say something useful.

Could you upload one of your "problematic" images somewhere, so I can download it? Thanks!