This recipe will reduce any image passed to it. Care must be taken to ensure that a proper flat-field image will be reduced.

The bad pixel mask applied is $ORAC_DATA_CAL/bpm.

The flat field is normalised using a clipped mean, where the clipping levels are 2, 3, and 3 standard deviationss. This value is effectively the mode of the image. The entire image is divided by this value to normalise it.

Intermediate frames are deleted.

The flat is called flat_$<$frame_number$>$.

The flat is filed in $ORAC_DATA_OUT/index.flat.

The processing engines are from the Starlink packages Kappa and Ccdpack.

Uses the Starlink NDF format.

History is recorded within the data files.

The title of the data is propagated through the intermediate file to the flat.

Variance information is not supported.