The intensity of the scattered light feature scales linearly with sky background which varies from image to image, so that the calibrated image has to be scaled and adjusted with respect to the background level of the input image in order to properly remove the central scattered light feature.
The background on the OM images depends on many factors, such as exposures time, spacecraft pointing direction, positions of the sun and the moon, etc. Therefore, one cannot simply use the exposure time of a given OM image for scaling the calibrated image.
The scaling factor can either be determined automatically by comparing the background levels of the same regions of the input and calibrated images or, alternatively, by setting the parameter scalingfactor to the desired value in order to force the task using a specific scaling factor.
Currently there are three available algorithms within the task for calculating the scaling factor (the algorithm is chosen by specifying the parameter mode=1,2 or 3, with the default value mode=1).
