do livestack controls affect raw images?

Discussion of using SharpCap for Deep Sky Imaging
Post Reply
jeruss
Posts: 16
Joined: Tue Oct 08, 2019 1:58 pm

do livestack controls affect raw images?

Post by jeruss » Fri May 08, 2020 4:16 pm

Greetings,

Do the stretching and color balancing controls used in livestacking affect the color balance of the raw images? I have a zwo asi 294 camera and want to compare a livestacked image to an image acquired by stacking the raw frames in dss and then processing it in gimp. I would like the raw images to be as neutral as possible without any processing. Thanks.

chongo228
Posts: 129
Joined: Fri Nov 24, 2017 3:34 am

Re: do livestack controls affect raw images?

Post by chongo228 » Fri May 08, 2020 6:29 pm

Images are saved raw unless you select tell SC otherwise.

"The three colour sliders can be used to adjust the colour balance of the image. The saturation slider can be used to increase or decrease the amount of colour seen. Adjustments made here affect the image as viewed on screen and the saved images when choosing either ‘Save With Adjustments’ or ‘Save Exactly as Seen"

https://docs.sharpcap.co.uk/3.2/#Live%2 ... 0Reference

jeruss
Posts: 16
Joined: Tue Oct 08, 2019 1:58 pm

Re: do livestack controls affect raw images?

Post by jeruss » Fri May 08, 2020 6:43 pm

Thank you for the reply. So does this mean that the controls on the right such as white balance, brightness, etc should be set on auto in order to get a raw image for the individual frames?

User avatar
admin
Site Admin
Posts: 4982
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: do livestack controls affect raw images?

Post by admin » Fri May 08, 2020 8:52 pm

Hi,

The white balance controls on the right-hand side in the camera control section should be set to their neutral values- that means that a value of 50 for ZWO cameras in the white balance controls 'White Balance (R)' and 'White Balance (B)'. If you set these controls to different values then the brightness of the different channels in the frame will have been adjusted before the image gets to SharpCap, even in raw mode.

Note that other brands of camera have different neutral values for the white balance controls (in some brands they even vary from model to model).

Cheers, Robin

jeruss
Posts: 16
Joined: Tue Oct 08, 2019 1:58 pm

Re: do livestack controls affect raw images?

Post by jeruss » Fri May 08, 2020 10:58 pm

Thanks so much. That clears it up for me.

umasscrew39
Posts: 350
Joined: Fri Apr 28, 2017 1:28 pm
Location: Central Florida
Contact:

Re: do livestack controls affect raw images?

Post by umasscrew39 » Sat May 09, 2020 12:22 pm

What is odd, to me, is that the ZWO cameras by default do NOT set the values to neutral (that is, 50/50). Maybe that is normal for all brands or just the way all of them open in SharpCap. They usually default to 95/5 instead of 50/50 and you have to remember to change it back or just save it as a profile, which is what I do.

User avatar
admin
Site Admin
Posts: 4982
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: do livestack controls affect raw images?

Post by admin » Sat May 09, 2020 6:46 pm

Hi,

Do the 95/5 values that get set give a reasonably neutral white balance? I can imagine that they might set up default value is like that to try to cut down on support calls from people who get stuck trying to get what they think of as 'correct colours' out of the camera. ZWO at one point had a gamma control available for the cameras, but removed it and I suspect a similar reason.

Cheers, Robin

umasscrew39
Posts: 350
Joined: Fri Apr 28, 2017 1:28 pm
Location: Central Florida
Contact:

Re: do livestack controls affect raw images?

Post by umasscrew39 » Sat May 09, 2020 11:05 pm

Hi Robin

Yes- it is reasonable. Never thought of that about support calls and I did not realize that they once had a gamma control. I guess it was before my time using SC :-) as I was a SX camera guy. The 50/50 works better, I think. Nowadays (as you helped with recently on other posts), I mainly capture individual raw images to then transfer to PixInsight. I do not do much live viewing anymore. I just make sure I do my darks and flats also at 50/50.

Regards,
Bruce

Kisslija
Posts: 1
Joined: Fri Jan 03, 2020 9:47 pm

Re: do livestack controls affect raw images?

Post by Kisslija » Wed Sep 02, 2020 11:02 pm

Hello everyone, I've been having an issue with color balance and was wondering if the white balance controls could be affecting my images. I image with an ASI294MC Pro with a Hyperstar on a Celestron 9.25 SCT. I've attached a couple images of recent images I took with an Optolong L-Enhance filter. The images are purple when stretched in Pixinsight before processing. I can remove most of the purple color using the automatic background extraction. However even after color calibration the colors are off. I have the white balance settings set to "auto".
M27 Non-Linear-Small.png
M27 Non-Linear-Small.png (371.87 KiB) Viewed 461 times
M27_drizzle_integration_ABE_NonLin_TGVDN_01Sep20 Small.png
M27_drizzle_integration_ABE_NonLin_TGVDN_01Sep20 Small.png (510.95 KiB) Viewed 461 times
On another note, I confused as to why the nebula core is so blown out.

The images were stacked using 120 second subs for a total integration time of 64 minutes, gain set at 120.

User avatar
admin
Site Admin
Posts: 4982
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: do livestack controls affect raw images?

Post by admin » Fri Sep 04, 2020 4:05 pm

Hi,

you can often get purple colours in the images if you are trying to process using the wrong Bayer pattern – if you are feeding raw images to pixinsight and then have selected the incorrect Bayer pattern then the colour of the output can be thrown completely off.

The best thing to do to check this out is to take a picture of something red using the camera – even if you are just holding a piece of red card in front of the camera with no lens or telescope attached to it. Process this image in the normal way and it should come out as red in the end. If it comes out with a green or blue cast then you have the wrong Bayer pattern selected and you need to try the different patterns until you find the one that gives you a red image.

Cheers, Robin

Post Reply