- Form: COLFIX source [BOX=n] [SPLINE] [ROWS]
[MAX=f] [SMOOTH] [MODE]
-
- source
- tells VISTA what image to work on
- BOX=n
- only use the image within box n
- SPLINE
- fit spline to deferred charge buffer
- ROWS
- fix rows instead of columns
- MAX=f
- Ignore pixels above this level
- SMOOTH
- Median filter buffer
- MODE
- Use modal estimator
COLFIX will attempt to fix deferred charge columns (or rows) under
the assumption that they can be fixed by additive corrections. Under
default operation, the routine finds the median of each column, and then
generates corrections to each column such that they all have the same
median. The median is selected is a super-median, of median of the the
original column medians. A number of fixes are given for crowded images or
those containing extended objects, where the median may be biased. The
SPLINE option fits a spline to the column medians in an attempt to preserve
and slow trends originally in the data. MAX sets an upper threshold to
exclude bright pixels that may bias the median, and MODE attempts to revise
the median by using the difference in value between the median and first
quartile to exclude bright pixels in the last quartile.