...

from pyimgalgos.RadialBkgd import RadialBkgd, polarization_factor

    X, Y, Z = geo.get_pixel_coords()
    rb = RadialBkgd(X, Y, mask, nradbins=500, nphibins=1) 
    pf = polarization_factor(rb.pixel_rad(), rb.pixel_phi()+phi_pf90, 91.33e3)

# in event loop:
    nda, title = rb.subtract_bkgd_interpol(arr * pf) * mask

...

Image corrected up to 80mm, 40<phi< 320:

OLD IMAGE PROCESSING

Subtract background shape evaluated in run 192. 

...

Averaged Fraser- transformed image using angles from fit to 2 arc peaks

Spectrum of intensities

Spectrum of intensities of all quad 2x1-segment 0 (close to beam) and 4 (water ring region)

before background subtraction

Image AddedImage Added

after background subtraction

Image AddedImage Added

• masked pixels contributes to peak at 0
• 1-, 2- and 3- photon peaks are seen
• common mode correction before background subtraction does not work well in this data sample due to significant fraction of 1-photon peak next to noise peak, which makes an offset due to illumination.
• common mode correction after background subtraction does not work - it moves noise peak to 0 and destroys background subtraction results.

References

• Mask Editor
•  Calibration Management Tool.
• Radial Background Subtraction Algorithm