ASIairplus and WBPP calibration Lights

juliansinger

Member
Feb 29, 2020
6
0
Hi all ,

I am fairly new to this , but have used Pixinsight a few years ago then got back into it. Recently bought a Redcat51, and ASIairPlus and took some images of M31. 180second lights, then did some darks, flats, bias.
Data was on a SD card already inserted into ASIair+. Took card out and put that into Mac and started Pixinsight latest version 1.8.9-1 and then started WBPP version 2.4.5
But getting problems loading my lights. The darks etc seem fine.
Also when trying to open and look at my Light frames one by one , get odd images which cant be stretched and error messages . As if the Lights files are corrupted or not right, yet the other types seem fine. They seem to be of reasonable size etc.

Not sure if I am doing something wrong with Pixinsight or the ASIair+ ?

I would be grateful for any advice.
Screenshot 2022-08-15 at 15.24.05.png
 

pfile

PTeam Member
Nov 23, 2009
7,792
488
can you post one of these lights to google drive or dropbox and post the link here? be sure to set the link to 'public'

rob
 

pfile

PTeam Member
Nov 23, 2009
7,792
488
does the camera mfg say that the bayer pattern is RGGB? as loaded, the image looks correct with GBRG which indicates that PI's fits reader direction is opposite from ASIAir's fits writer direction.

rob
 

pfile

PTeam Member
Nov 23, 2009
7,792
488
i meant the camera manufacturer, that is, what does ASI say about the bayer matrix pattern for this camera? usually it is RGGB but i just wanted to make sure.

the green cast is totally normal - since there are 2 green pixels in each bayer quad, an Auto STF with channels locked will show a green image. but if you unlock the channels in STF you'll see something that looks a lot more normal.

rob
 

pfile

PTeam Member
Nov 23, 2009
7,792
488
so this means that either you need to somehow change the FITS writer order in ASIAir, or somehow cause ASIAir to write the ROWORDER fits keyword. if neither of those things are possible, then you need to set the FITS reader direction in PI to bottom-up.

are you using WBPP? i think there is a checkbox in there to set the fits reader direction. otherwise you have to pass the format hint "bottom-up" to the first process that reads in the files (likely ImageCalibration) and/or change the global fits reader direction to bottom-up by opening the format explorer tab on the left, double-clicking FITS, and changing the reader direction in the dialog box that pops up.

rob
 

juliansinger

Member
Feb 29, 2020
6
0
Thanks Rob, on Pixinsight WBPP I have tried checking thebottom up box but still no success with the Lights files. Its very odd. I took some images the week before with same kit and when looking at the preview images of M31 seemed to have good data. But when I downloaded the actual fits the images were very faint and dark unlike the previews.
 

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juliansinger

Member
Feb 29, 2020
6
0
Update:
A friend advised me to try ASI Studio. In fact this does open the Lights properly and calibrate my Lights with darks flats and bias . Its a bit basic but works fine with these files.

I can then transfer the resultant calibrated FITS file back into Pixinsight for further processing.

I noticed going back to Pixinsight, when the initial opening of these colour images it seems to register them as black and white thus Grey when STF stretching. And does not really stretch them much. Yet the header in FITS files says it RGGB.
 

pfile

PTeam Member
Nov 23, 2009
7,792
488
well this is just one of those things... all camera sensors are mono - they are sensitive to some UV all the way down to infrared. in order to get colors, you need a filter. with a mono camera, you use a filter wheel. one-shot color cameras have a built in filter array called a bayer matrix. so if you open a bayered FITS file, it's always going to be mono. the RGGB indicates the filter pattern, for use by the Debayer process to figure out how to assign a given pixel to a given color channel when it creates the RGB image.

rob