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ASI290 mono software binning issue
http://zwoug.org/viewtopic.php?f=21&t=6639
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Author:  GuLinux [ Thu Jun 01, 2017 7:51 am ]
Post subject:  Re: ASI290 mono software binning issue

Sam wrote:
the hardware binning of 1600 is different from other cameras
the brightness will increase by 4X if you choose hardware binning
you cannot see from the image if you enable software binning under RAW16
the brightness will increase by 4X too if you choose RAW8 output


Thanks, but different how?

In the user manual, it is suggested to use software binning, unless you care about transfer speed.
However, if you want to just shorten exposure time for RGB (which as far as I know is one of the main advantages of binning) the software binning algorithm appears to be useless: it's so dark that the exposure time should be roughly the same as the unbinned exposure.

Author:  Sam [ Fri Jun 02, 2017 1:35 am ]
Post subject:  Re: ASI290 mono software binning issue

GuLinux wrote:

Thanks, but different how?

In the user manual, it is suggested to use software binning, unless you care about transfer speed.
However, if you want to just shorten exposure time for RGB (which as far as I know is one of the main advantages of binning) the software binning algorithm appears to be useless: it's so dark that the exposure time should be roughly the same as the unbinned exposure.


hardware binning method depends on sensor, different sensor use different way
and one thing clear is that software binning is the best way to improve SNR
SNR is the most important part when you do binning
so don't judge by just brightness

Author:  GuLinux [ Mon Jun 19, 2017 12:52 pm ]
Post subject:  Re: ASI290 mono software binning issue

Sam wrote:
hardware binning method depends on sensor, different sensor use different way
and one thing clear is that software binning is the best way to improve SNR
SNR is the most important part when you do binning
so don't judge by just brightness


I've been thinking about it... But there's still something nagging me.
Let's see if I got everything clear, first: on hardware binning increases brightness by adding pixel values, while software binning does an average, therefore brightness remains the same, but SNR increases.

With hardware binning you get more noise, alright, but with the reduced exposed time, you can then shot a much greater number of frames, to help improve SNR.

With software binning you would then require less shots to have the same image quality. But since brightness is unchanged, you would then require a longer exposure. With filters, you would roughly need 3 times the exposure of the L channel.
This, in theory, is not a bad thing: you just do longer exposures, but with the need of stacking much less frames, given the improvement in the SNR. But longer exposures also means having a much greater "risk" factor: tracking errors, satellites or airplanes in the field, cosmic rays, etc.

In my specific case, I don't have an autoguiding setup, just a Star Adventurer and a DSLR lens, so the longer exposure is much less attractive to me than the additive binning.

Did I mistake something?

Thanks

Author:  Sam [ Mon Jun 26, 2017 1:19 am ]
Post subject:  Re: ASI290 mono software binning issue

GuLinux wrote:
I've been thinking about it... But there's still something nagging me.
Let's see if I got everything clear, first: on hardware binning increases brightness by adding pixel values, while software binning does an average, therefore brightness remains the same, but SNR increases.

With hardware binning you get more noise, alright, but with the reduced exposed time, you can then shot a much greater number of frames, to help improve SNR.

With software binning you would then require less shots to have the same image quality. But since brightness is unchanged, you would then require a longer exposure. With filters, you would roughly need 3 times the exposure of the L channel.
This, in theory, is not a bad thing: you just do longer exposures, but with the need of stacking much less frames, given the improvement in the SNR. But longer exposures also means having a much greater "risk" factor: tracking errors, satellites or airplanes in the field, cosmic rays, etc.

In my specific case, I don't have an autoguiding setup, just a Star Adventurer and a DSLR lens, so the longer exposure is much less attractive to me than the additive binning.

Did I mistake something?

Thanks


this is not correct
because you can turn up gain to reach the same brightness with software binning
and still better SNR than hardware binning
because most hardware binning donot bin all the pixels
such like bin3, it may only bin 2 lines and skip 1 line

Author:  GuLinux [ Tue Jun 27, 2017 12:39 pm ]
Post subject:  Re: ASI290 mono software binning issue

Oh right.. you can adjust gain.
I'll give it a go then!
Thanks

Author:  Hs9 [ Fri Aug 18, 2017 4:20 pm ]
Post subject:  Re: ASI290 mono software binning issue

Sam,

Based on my measurements it appears that in 16bit mode the ZWO SDK is averaging the pixels when I select x2 bin.

Can you please fix this. It is causing issues for me. Note that averaging adjacent pixels and then increasing gain is not mathematically equivalent to binning.

Binning is a standard function that is defined as "SUM" of adjacent pixels. Changing the operation to a non-standard operator is not useful and just confuses users.

Thanks

Author:  Sam [ Mon Aug 21, 2017 2:20 am ]
Post subject:  Re: ASI290 mono software binning issue

Hs9 wrote:
Sam,

Based on my measurements it appears that in 16bit mode the ZWO SDK is averaging the pixels when I select x2 bin.

Can you please fix this. It is causing issues for me. Note that averaging adjacent pixels and then increasing gain is not mathematically equivalent to binning.

Binning is a standard function that is defined as "SUM" of adjacent pixels. Changing the operation to a non-standard operator is not useful and just confuses users.

Thanks

we did use sum with 16bit mode
but you need to know 290 has only 12bit ADC, it become 14bit when you sum up 4 pixel
there is enough space to put 14bit in the proper position of 16bit data
if you wish to see brightness changes, just shift the data by 2 bits, that's what you want

Author:  Hs9 [ Mon Aug 21, 2017 2:59 am ]
Post subject:  Re: ASI290 mono software binning issue

Ok. So what you are saying is that when I am using 16bit output mode but no binning, the 12 bits from the ADC occupy the higher order bits? But when I select x2 bin the resulting 14bit output is shifted to the lower order bits so the top 2 bits are always empty? Is that correct?

Thanks

Author:  Sam [ Mon Aug 21, 2017 5:11 am ]
Post subject:  Re: ASI290 mono software binning issue

Hs9 wrote:
Ok. So what you are saying is that when I am using 16bit output mode but no binning, the 12 bits from the ADC occupy the higher order bits? But when I select x2 bin the resulting 14bit output is shifted to the lower order bits so the top 2 bits are always empty? Is that correct?

Thanks



yes, 12bit or 14bit all occupy the higher order bits, the low 2 bits are always empty
Image
you can read this article
http://www.skyinspector.co.uk/zwo-cmos- ... eo-cameras

Author:  Hs9 [ Mon Aug 21, 2017 5:31 am ]
Post subject:  Re: ASI290 mono software binning issue

Thanks. Appreciate the clarification.

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