Figure 4
(a) Intensity profile of a vertical line of pixels across the detector image [see also Fig. 3(a)] before and after using the rolling ball algorithm. The x-axis represents pixels with different distance to the upper pixel of the line on the detector. The y-axis represents the intensity values of the corresponding pixels. The red solid line corresponds to the raw image, the blue solid line corresponds to the resulting background, and the green line corresponds to the corrected image. (b) The fraction of pixels whose intensity is larger than the threshold value and the first derivative of the fraction of pixels with respect to the tested radius (the parameter of the rolling ball algorithm r) plotted as a function of radius. |