SharpCap Forums

I'm using SharpCap v. 3.1.5164. I have a Win10Pro 64 bit laptop, and am using a ZWO 1600MC-Cool camera, with latest ZWO drivers. Using previous SC versions, I have successfully used Bin2 with Hardware Binning On during live-stacking (and using matching master dark and master flat), and have been able to get good color balance using the auto color balance button (lightening bolt) during live stacking.

Steps to reproduce:
Using Gain 300, Brightness 50. I changed from Bin1 to Bin2, and turned Hardware Binning On. I was also using matching master dark and master flat. I then started live-stacking. After a couple of images were stacked, I tried using the lightening bolt button for auto-color balance as well as using the histogram auto-stretch. The color sliders did not move from their default positions. I tried doing a manual color balance by moving the sliders but could not balance the color.
For example, here is a previous effort with v. 3.1.5132.0 using Bin2 with Hardware Binning On with matching master dark and master flat:

And I've attached the log file from that session (was using v. 3.1.5132.0).

I've attached the log files from my previous session with v. 3.1.5132.0 where this was working. I've also attached the log file from last night using v. 3.1.5164 where this feature did not work.

Hi,

I'm wondering if the problem is that there's really not much there to colour balance on - there's very little visible between the dark background and the saturated stars. You can't colour balance on a star because one or more channels is saturated which throws everything off and colour balancing on the background isn't very useful either. Give it a try on a daylight scene with the same settings and check that does have some effect (ie moves the sliders). If it doesn't then maybe a bug, otherwise I'm thinking that you are running up against limitations in the way the colour balance works.

cheers,

Robin

Is there a rule of thumb for how long I need to stack or how much signal SC needs before there is enough for color balance to work? Thanks.

Hi,

basically the auto-white-balance feature will try to align the peaks of the R/G/B histograms. If the peak is at the RHS or the black point then this will most likely confuse it into doing nothing. It will work best on nebulosity and galaxies where you have a decent amount of histogram coming in the mid levels.

If you have the image you posted above in full size and full bit depth then please share a link to it and I will see if I can learn anything from it to improve the AWB funcitonality.

cheers,

Robin

Hi Robin,

I tried again last night using Bin2 and Hardware binning on, live-stacking for 10 minutes on the Owl Nebula with a matching master dark and master flat. At no time was I able to use the auto color balance; clicking the lightening bolt did nothing. I tried using the color sliders, but could not balance the color. I've linked to the full-size, full depth image "saved as viewed".

https://www.dropbox.com/s/xnxbi5p9r7gu1 ... s.png?dl=0

I've attached the camera settings for that image here. Thanks for taking a look.

Thanks for the file -it's difficult to say anything for sure about it because the 'save as viewed' file has already been stretched by SharpCap so won't respond to AWB in the same way that the original data would. All I can say is that when I load it up into the test camera I do get a response from AWB (it boosts the red and blue channels a lot).

I have put some logging into the places where something could be going wrong with the AWB in the latest build (3.1.5174), so if you encounter the problem again then please send me the SharpCap log and (if possible) a 'Save as 16 bit Stack' image (or a raw frame).

thanks,

Robin

Hi Robin,

I used v. 3.1.5174 last night with good results! Whatever changes you made, they definitely helped. Using Bin2 with Hardware Binning On, I first manually balanced the Red and Blue channels to overlap with the Green channel, using the image histogram (not the live stack histogram). Then I started live-stacking. Clicking the lightening bolt for Auto Color Balance during live stacking produced an immediate change in the color balance, unlike in previous versions. I was able to get good color balance for all the objects I live-stacked.

Here's the 16-bit stack .fits file: https://www.dropbox.com/s/57low5qfeeyuk ... .fits?dl=0

Saved as viewed image: https://www.dropbox.com/s/f1k35q4b39hff ... s.png?dl=0

Here's the log file: https://www.dropbox.com/s/lniroj7mflcox ... 2.log?dl=0

Thanks.

That's good news - the image looks good too

I did change the code to ignore black pixels and fully saturated ones when calculating the AWB, which will probably help if focus on balancing the mid ranges of the image which is where all the interesting action is. If you do get any further problems then let me know, but I will mark this one as fixed for now if that's OK.

thanks,

Robin