Rejection algorithms

ConceptPercentile Clipping⚓

This is a one step rejection algorithm ideal for small sets of data (up to 6 images).

ConceptSigma Clipping⚓

This is an iterative algorithm which will reject pixels whose distance from median will be farthest than two given values in sigma units(σlow, σhigh).

ConceptMedian MAD clipping⚓

It is similar to the sigma clipping except the median absolute deviation (MAD) is used instead of the standard deviation to compute the rejection bounds around the median of the stack.

ConceptMedian Sigma Clipping⚓

This is the same algorithm as Sigma Clipping except than the rejected pixels are replaced by the median value of the stack.

ConceptWinsorized Sigma Clipping⚓

This is very similar to Sigma Clipping method Sigma Clipping

Note

It uses an algorithm based on Huber's work 1[1] 2[2]

ConceptGeneralized Extreme Studentized Deviate Test⚓

GESDT

ConceptLinear Fit Clipping⚓

It fits the best straight line (y=ax+b) of the pixel stack and rejects outliers. This algorithm performs very well with large stacks and images containing sky gradients with differing spatial distributions and orientations.

This is an algorithm developed by Juan Conejero[2], main developer of PixInsight.

Note

This algorithm is very efficient to remove satellite/plane tracks.