Best? method to resize calibration images?

[basilr]

I was wondering your thoughts on the best? way to resize/resample images from a photometric POV.

I have some science images and calibration images with different binning. The science images, darks, and bias are all 2x2 binning, the flats are 1x1 (same telescope, CCD). I’ve been told (from a reliable source) it’s okay to resize the flats to 2x2, but not the darks or bias, and upscaling is just not an option. I see AIJ has several options to resize images (average/no average combined with none, bilinear, and bicubic) – Image-adjust-size. Any thoughts on which method would “best” preserve photometric accuracy? I’ve done a little testing, comparing the stats of an original 1x1 flat to its resampled version using various combinations and it _seems_ the bilinear with averaging is generally a closest match, but I’m not sure that is even a valid test.

Any guidance is greatly appreciated!

Thanks
Basil

[karenacollins]

Hi Basil,

I don't personally have experience re-binning calibration images, but I'd expect average combined with none would be the best for re-binning a flat.

Karen

On 1/5/2019 9:39 AM, basilr [via AstroImageJ] wrote:

I was wondering your thoughts on the best? way to resize/resample images from a photometric POV.

I have some science images and calibration images with different binning. The science images, darks, and bias are all 2x2 binning, the flats are 1x1 (same telescope, CCD). I’ve been told (from a reliable source) it’s okay to resize the flats to 2x2, but not the darks or bias, and upscaling is just not an option. I see AIJ has several options to resize images (average/no average combined with none, bilinear, and bicubic) – Image-adjust-size. Any thoughts on which method would “best” preserve photometric accuracy? I’ve done a little testing, comparing the stats of an original 1x1 flat to its resampled version using various combinations and it _seems_ the bilinear with averaging is generally a closest match, but I’m not sure that is even a valid test.

Any guidance is greatly appreciated!

Thanks
Basil

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[basilr]

Thanks Karen, this helps!

Dennis Conti's answer

http://astroimagej.1065399.n5.nabble.com/Impact-on-binning-on-CCD-parameters-gain-readout-noise-dark-current-tp1020.html

also helps.

Basil