The algorithm used to prevent the detection of spurious sources near sharp gradients in the exposure (e.g. chip edges) has been changed as of version ewavelet v3.3 .
The background map is convolved with the current wavelet filter.
This convolved image should show similar features as the convolved
input image, if no real sources were present.
We only retain sources whose value of 
exceeds
the corresponding pixel value in the convolved background map
by at least a factor of edgethreshold.