Up to and including the August 2004 run, there was an unsuspected problem with the binning of the ultracam chips. What happened was that if, say, you binned by 3 in X, then the 2 closest pixels in X to the readout were lost from every pixel. If you binned by N in X then the N-1 pixesl closest to the readouts were lost. This obviously loses flux (and so the problem has since been fixed), but also means that using the routine crop to bin up an unbinned frame, e.g. a flat field, is not accurate. The purpose of this routine is to modify a frame so that when crop is applied, the end result is OK. It does this by setting the 'lost' pixels to zero and making sure that there appear windows that when binned will match the supplied template binned frame.
NB This routine MUST only be applied to a frame after it has been bias-subtracted (the same applies to crop for that matter).
bcrop input template output
| input | --- | Input frame |
| template | --- | Binned frame that acts as a template |
| output | --- | Output frame which will be cropped & binned allowing for the problem. |
It only makes sense to use this routine on unbinned frames and you will not be able to use it on any other type.
This command is a member of the classes: Manipulation, Programs.
Author: T.R. Marsh
Created: 06 October 2005
Revised: 12 October 2005