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Binning OSC IMX571/IMX455

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#1 ChrisWhite

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Posted 23 October 2021 - 10:30 AM

There is really not much out there on whether or not this works well.  I'm not talking about hardware binning, but on-camera software binning.  Are colors still retained?  Is there something strange in the post-ADC pixel combination as to why this might not be recommended.  I'm trying to get my head around how data would be combined with a bayer matrix in play.  Please don't discuss bin1 and resample in post processing.  We all know that works just fine.  This is a thread about binning in camera. 

 

Thank you,



#2 jdupton

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Posted 23 October 2021 - 10:42 AM

Chris,

 

   There are two modes for binning a ZWO OSC camera. One is the default of "Color-binning" and the other is "Mono-binning". Both are done in the device driver rather than on sensor / in-camera (I think). They give different results and can be used for different purposes. There was a recent thread where the modes were discussed. I made a long post there about the "resolution" aspects related to Color-Binning in the driver versus doing a similar operation later in post-processing. Check out the whole thread for other views.

 

https://www.cloudynights.com/topic/788022-to-bin-or-not-to-bin/#entry11352974

 

   If I wish to employ binning for an image, I do it in post-processing. However, I choose to set the Mono-Binning flag in the ASCOM driver. This means that I always shoot at 1x1 binning for imaging. However, I use 2x2 for plate solving and focusing under SGP. This results in the downloaded image being monochrome and gives me more consistent results (because of the lack of the CFA matrix pixilation effects). For framing, I use 3x3 (mono) binning for the faster frame rates.

 

 

John


Edited by jdupton, 23 October 2021 - 10:54 AM.

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#3 ChrisWhite

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Posted 23 October 2021 - 10:56 AM

Chris,

 

   There are two modes for binning a ZWO OSC camera. One is the default of "Color-binning" and the other is "Mono-binning". Both are done in the device driver rather than on sensor / in-camera (I think).They give different results and can be used for different purposes. There was a recent thread where the modes were discussed. I made a long post there about the "resolution" aspects related to Color-Binning in the driver versus doing a similar operation later in post-processing. Check out the whole thread for other views.

 

https://www.cloudynights.com/topic/788022-to-bin-or-not-to-bin/#entry11352974

 

   If I wish to employ binning for an image, I do it in post-processing. However, I choose to set the Mono-Binning flag in the ASCOM driver. This means that I always shoot at 1x1 binning for imaging. However, I use 2x2 for plate solving and focusing under SGP. This results in the downloaded image being monochrome and gives me more consistent results (because of the lack of the CFA matrix pixilation effects). For framing, I use 3x3 (mono) binning for the faster frame rates.

 

 

John

John,

 

I was hoping you would chime in.  Interesting post you link to.  Actually, I'm surprised that the biggest deterrent is the sampling loss with binning OSC.  That to me is very interesting and while obvious in hindsight was not something I was considering.  This I suppose leads to another consideration.  I'm planning to use my OSC camera to sample color data and my mono camera to sample luminance at a higher resolution. 

 

So, at what point is color data undersampled for the luminance data it is intended to be used with?  In the "old" days with CCD (and the current days for people who realize these cameras are still relevant) we would bin1 for lum and bin2 with color.  This seemed to work and not "confuse" color association when combined with the higher resolution mono.

 

In my case, I would be imaging mono at 1.78"/px on one scope, and then on another scope the color data would natively be 1.59"/px or if I binned 2 (using the 1/3 less sampling consideration you outline) I would be at 4.77"/px.  (which correct me if I am wrong is like binning 3x with mono bin)

 

That would have luminance data at about 2.7x the resolution of the color data if I binned the OSC.  Maybe this would be fine enough sampling on color data, but I would worry about bleed of color when applied to the luminance.  


Edited by ChrisWhite, 23 October 2021 - 10:58 AM.


#4 bobzeq25

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Posted 23 October 2021 - 11:41 AM

John,

 

I was hoping you would chime in.  Interesting post you link to.  Actually, I'm surprised that the biggest deterrent is the sampling loss with binning OSC.  That to me is very interesting and while obvious in hindsight was not something I was considering.  This I suppose leads to another consideration.  I'm planning to use my OSC camera to sample color data and my mono camera to sample luminance at a higher resolution. 

 

So, at what point is color data undersampled for the luminance data it is intended to be used with?  In the "old" days with CCD (and the current days for people who realize these cameras are still relevant) we would bin1 for lum and bin2 with color.  This seemed to work and not "confuse" color association when combined with the higher resolution mono.

 

In my case, I would be imaging mono at 1.78"/px on one scope, and then on another scope the color data would natively be 1.59"/px or if I binned 2 (using the 1/3 less sampling consideration you outline) I would be at 4.77"/px.  (which correct me if I am wrong is like binning 3x with mono bin)

 

That would have luminance data at about 2.7x the resolution of the color data if I binned the OSC.  Maybe this would be fine enough sampling on color data, but I would worry about bleed of color when applied to the luminance.  

Theoretically the color would bleed.  In practice the effect is less, maybe unnoticeable, because of the way your eyes work.  They see detail in black and white, not color.

 

That's why people binned color in LRGB.  It's interesting that the practice has gone in and out of fashion.  People sometimes add unbinned color to luminance to get better snr.

 

This is one of those deals where actually trying things is better than theoretical musing.  Too much going on.  You could shoot color at higher resolution, try binning in software, and see what happens.  Pretty easy to do the experiment, and see how much you can bin in software before you see undesirable (to you) effects.


Edited by bobzeq25, 23 October 2021 - 11:45 AM.


#5 ChrisWhite

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Posted 23 October 2021 - 12:15 PM

Theoretically the color would bleed. In practice the effect is less, maybe unnoticeable, because of the way your eyes work. They see detail in black and white, not color.

That's why people binned color in LRGB. It's interesting that the practice has gone in and out of fashion. People sometimes add unbinned color to luminance to get better snr.

This is one of those deals where actually trying things is better than theoretical musing. Too much going on. You could shoot color at higher resolution, try binning in software, and see what happens. Pretty easy to do the experiment, and see how much you can bin in software before you see undesirable (to you) effects.


That's a good point Bob. Easy enough to take native data and resample the color a few ways to see at what point the undersampling makes a difference in the final product.

In fact I have hard drives full of data that I could so this with now. Why didn't I think of that!?

Thanks.
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#6 TelescopeGreg

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Posted 23 October 2021 - 01:59 PM

I'm not sure which sensor is in the ASI2600MC, but binning on-camera does preserve color.  Unfortunately, I do not see a huge improvement in SNR or such from the camera by doing so.  Rather, the primary benefits to binning on-camera is that the images download 4x faster, and take up 1/4 the disk space.



#7 ChrisWhite

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Posted 23 October 2021 - 02:23 PM

I'm not sure which sensor is in the ASI2600MC, but binning on-camera does preserve color. Unfortunately, I do not see a huge improvement in SNR or such from the camera by doing so. Rather, the primary benefits to binning on-camera is that the images download 4x faster, and take up 1/4 the disk space.


That's the imx571. Thanks for the feedback. Based on John's analysis, it seems that binning with osc only makes sense if you are oversampled by a factor of 3x. Which is easy to do if using on a 2 meter+ telescope. Interesting that you didn't see the improvement in SNR.

#8 TelescopeGreg

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Posted 23 October 2021 - 10:44 PM

That's the imx571. Thanks for the feedback. Based on John's analysis, it seems that binning with osc only makes sense if you are oversampled by a factor of 3x. Which is easy to do if using on a 2 meter+ telescope. Interesting that you didn't see the improvement in SNR.

There may be some SNR improvement, but I haven't tried measuring it.  From using the camera for about a year now, binning 2x2 on-camera doesn't seem to be the "wow" game changer in terms of etendue that I had hoped for.  I use it mostly for the time and space it saves during imaging, stacking, and processing.




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