Update on binning for small pixel/large chip cameras

[gboyle]

Hi all
i noticed a number of threads but didnt see anything recent on binning and this may have been because the issue is solved but thought i would check.

I have an sCMOS camera that has 3.75um pixels and potentially very low read noise and want to compare it to my older camera with 13.5um pixels. the 3.75 pixels have decent well depth that in theory if binned together can get close to the 13.5um version...

the scmos images I am being told i should bin in software to improve the SNR.

is there a way to do this in AIJ so that i can take unbinned 16 bit data and combine without to improve the snr before i proceed to transit fitting? i saw 2018 posts saying (i think) that this was on the to-do list...

thanks
gavin

[karenacollins]

Hi Gavin,

Although I don't think it will change you photometric result, you can do pixel binning using:
Toolbar > Image > Adjust > Size

For instance, if you have 4096 x 4096 images, scale them 2x2 by entering these values:

(the depth is the number of images in your stack and shows the appropriate number by default)

I think it would be best to make sure you scale by integer values (e.g. 2x2, 3x3, 4x4, etc.) and disabled the interpolation option as shown above.

I'd encourage you to conduct some tests by running photometry before and after interpolation for a couple of examples to see if this step is really improving your photometry. You'd of course need to use different size photometry radii in each case to match the different PSF sizes in pixel space.

Karen

On 10/21/2020 9:12 PM, gboyle [via AstroImageJ] wrote:

Hi all
i noticed a number of threads but didnt see anything recent on binning and this may have been because the issue is solved but thought i would check.

I have an sCMOS camera that has 3.75um pixels and potentially very low read noise and want to compare it to my older camera with 13.5um pixels. the 3.75 pixels have decent well depth that in theory if binned together can get close to the 13.5um version...

the scmos images I am being told i should bin in software to improve the SNR.

is there a way to do this in AIJ so that i can take unbinned 16 bit data and combine without to improve the snr before i proceed to transit fitting? i saw 2018 posts saying (i think) that this was on the to-do list...

thanks
gavin

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[gboyle]

thanks Karen

I will look at that - in case others have been down this road and know the differences it appears in my search for software binning to increase SNR I should be considering:

toolbar> image>adjust>size

and
toolbar> image>scale

and for my image stack
toolbar>process>batch convert (and adjust the scale figure - am not sure if this is a batch version of either of the above or not)

I will advise if/when i can figure it out.
best
gavin