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ASIAIR Binning

ZWO ASIAIR CMOS Binning One-Shot Color
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Clayton Ostler avatar
Clayton Ostler avatar
To be clear this is not a "don't bin an OSC camera" conversation, and not a "bin it in post" conversation. 

I also don't want to have the ridiculous argument about "there is no HW binning on CMOS or in OSC cameras."

ZWO just confirmed the color ASI2600MC cameras support HW binning, and I also already understand that it is not as good as monochrome binning and might be some firmware trickery, however it supported and done in camera. 

Question for discussion:
The ASIAIR has binning options for the ASI2600MC cameras, however it never specifies if it is hardware or software binning. The camera supports both hardware and software binning and the ASICAP PC app lets you select if you want to do hardware or software binning.

However in the ASIAIR there is no way to see if its hw or sw, any ideas on how to know or check? 
Is there somewhere hidden in the air UI to choose? 
Does the air just default to HW when its available? 

The idea is I want to use the 2600mc binned at 4x4 for EAA  (getting images to the screen as quickly as possible) Binning will gather more light, and make the images smaller, I know some info is lost because its color, but the truth is that info is lost because its color regardless.
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Tony Gondola avatar
Tony Gondola avatar
It's my understanding that all binning with a cmos camera is software, it's just a matter if it happens in camera or downstream. Have you tried it with you ASIAIR? How does it look?
SemiPro avatar
SemiPro avatar
Clayton Ostler:
The ASIAIR has binning options for the ASI2600MC cameras, however it never specifies if it is hardware or software binning. The camera supports both hardware and software binning and the ASICAP PC app lets you select if you want to do hardware or software binning.

You are unlikely to notice a difference. If it is for EAA then I wouldn't even fuss over it. Just get out there and enjoy some views!
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dkamen avatar
dkamen avatar
There are two types of CMOS binning: add 4 pixels (or 9 or 16) or average them but with integer division which is slightly imprecise. They can both be done in software or hardware, I am nor sure what is supported by the IMX571 in each of its modes. If you can find the sensor's datasheet it will say (unfortunately only a 2-page leaflet is available in Sony's website).

Anyway, unlike CCD where binning is an electronic operatio  where the analog pixel from 4,9, 16 pixels is read as one value and then digitized, CMOS binning is always a mathematical operation. Software binning is done by the driver while hardware binning is done on chip.

The main *practical* difference between the two modes is with software binning download time is about the same as no binning, because the 1x1 image is transferred to the computer normally and then scaled down by the driver. In fact, it could be a little slower because of that extra step which involves tens of millions mathematical operararions. But with hardware binning you get a smaller file straight from the camera so it takes less time to download.

If you are using 4x4 binning with the IMX571 that difference in download time woulf be quite significant, especially with an ASIAIR, because the little single board PC needs to fetch and process only 3MB instead of 50. 

So if you notice images are indeed arriving 16 times faster, it is hardware binning. Otherwise, it is software binning.

FWIW the Indi driver for ASI (which is what ASIAIR is based on) has no concept of different bin types and sets its memory buffer based on the dimensions of the binned image. Which (alongside the universal experience of super high framerates when binning) is a very strong indication binning is always done in hardware. 

Cheers,
Dimitris.
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Clayton Ostler avatar
Clayton Ostler avatar
Well I'm going to report my results, trying with the asiair for EAA, which means I'm using live stacking.

It does create an image much faster when it is binning, I set this to 4x4 binning and started live stacking with 30 second subs. It does create an image that is visible much quicker than using 1x1 binning. Maybe 2x faster. 

To be honest I'm not sure if it's the ASI air doing the binning, or the firmware on the device. What I can say is that the number of hot pixels that appear in the image seems to be much higher, which I don't really understand. 

I guess I could take some calibration frames for 4x4 binning and see if it cancels out the hot pixels. But I'm still not really sure if this is happening on the ASI air with software or on camera ie hardware.
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Clayton Ostler avatar
Clayton Ostler avatar
Well I'm going to report my results, trying with the asiair for EAA, which means I'm using live stacking.

It does create an image much faster when it is binning, I set this to 4x4 binning and started live stacking with 30 second subs. It does create an image that is visible much quicker than using 1x1 binning. Maybe 2x faster. 

To be honest I'm not sure if it's the ASI air doing the binning, or the firmware on the device. What I can say is that the number of hot pixels that appear in the image seems to be much higher, which I don't really understand. 

I guess I could take some calibration frames for 4x4 binning and see if it cancels out the hot pixels. But I'm still not really sure if this is happening on the ASI air with software or on camera ie hardware.
There are two types of CMOS binning: add 4 pixels (or 9 or 16) or average them but with integer division which is slightly imprecise. They can both be done in software or hardware, I am nor sure what is supported by the IMX571 in each of its modes. If you can find the sensor's datasheet it will say (unfortunately only a 2-page leaflet is available in Sony's website).

Anyway, unlike CCD where binning is an electronic operatio  where the analog pixel from 4,9, 16 pixels is read as one value and then digitized, CMOS binning is always a mathematical operation. Software binning is done by the driver while hardware binning is done on chip.

The main *practical* difference between the two modea is with software binning download time is about the same as no binning, because the 1x1 image is transferred to the computer normally and then scaled down by the driver. In fact, it could be a little slower because of that extra step which involves tens of millions mathematical operararions. But with hardware binning you get a smaller file straight from the camera so it takes less time to download.

If you are using 4x4 binning with the IMX571 that difference in download time woulf be quite significant, especially with an ASIAIR, because the little single board PC needs to fetch and process only 3MB instead of 50. 

So if you notice images are indeed arriving 16 times faster, it is hardware binning. Otherwise, it is software binning.

FWIW the Indi driver for ASI (which is what ASIAIR is based on) has no concept of different bin types and sets its memory buffer based on the dimensions of the binned image. Which (alongside the universal experience of super high framerates when binning) is a very strong indicator binning is always done in hardware. 

Cheers,
Dimitris.

With that information I'm going to assume that it's doing hardware meaning because it does download much faster.