Clarification on "XY binning" in BrightSense

[ple]

Hi ST Support,

A few datasheets for the BrightSense series, eg. um3224, show an option under CFG: Streaming readout mode control which is not precisely described in the documentation.

"-0x06: = XY binning x2"

How does this differ from "-0x01: = digital binning x2"?

The documentation says that digital binning is vertical+horizontal.

"Digital binning digitally combines every two pixels in horizontal and vertical directions to create the pixel output.
This solution averages the pixel photoshot noise and improves the SNR without impacting the frame rate."

Thank you!

[Jean_Poire · Accepted solution]

Hi @ple ,

The binning is done the same way for digital and XY binning. The difference is that the XY binning is an analog binning. It allows to save some time in the isp pipe.  

Best regards,

Jean 

[ple]

Hello Jean,

Thank you for the reply. The documentation refers to:

-0x00: = normal streaming
-0x01: = digital binning x2
-0x02: = digital binning x4
-0x03: = subsampling x2
-0x04: = subsampling x4
-0x05: = subsampling x8
-0x06: = XY binning x2

What is confusing here is the naming. The documentation refers to "analog subsampling," but your comment is the first one referring to 0x06 as analog binning. I suppose it is implied because 0x01 and 0x02 state "digital," but then it is ambiguous whether 0x03/0x04/0x05 are analog (skipping ISP pipe) or digital (adding delay in ISP pipe).

"Analog subsampling retrieves every two pixels in horizontal and vertical directions from the image matrix prior to
their entry into the digital image pipe. There is no noise improvement, but the frame rate can be almost doubled
by the reduction of the FRAME_LENGTH parameter."

Would this amended table be accurate?

-0x00: = normal streaming
-0x01: = digital binning x2
-0x02: = digital binning x4
-0x03: = n/a subsampling x2
-0x04: = n/a subsampling x4
-0x05: = n/a subsampling x8
-0x06: = analog XY binning x2

We will investigate options with our sensors, but it would be helpful to understand if this is correct.

[Jean_Poire]

Hello @ple,

I agree that the naming is a bit confusing. subsampling is always done at analog level. The correct amended table would be the following:  

-0x00: = normal streaming
-0x01: = digital binning x2
-0x02: = digital binning x4
-0x03: = analog subsampling x2
-0x04: = analog subsampling x4
-0x05: = analog subsampling x8
-0x06: = analog XY binning x2

Best regards,

Jean