NAME

bjdetect -- Detect bias jumps in a CCD overscan image.

USAGE

bjdetect input thresh nbins ncomp

DESCRIPTION

This task divides the CCD overscan image into NBINS equal subsections along the y-axis. It then takes the mean value of each subsection and compare with each other. If the difference between any pair is over the threshold value THRESH, it will print out a message to announce a detection of bias jump.

PARAMETERS

input [string]

Input image(s).

thresh [real]

Criterion of bias detection, in DN.

nbins [int]

Number of subsections the overscan is divided up to.

ncomp [int]

Number of neighboring subsections (in either direction) each subsection will be compared with. For example, if ncomp = 2, then subsection #1 will be compared with #2 and #3, but subsection #5 will be compared with #3, #4, #6, and #7.

(x1) [int]

Sometimes the overscan image will contain information other than the bias. For example, the WPPC2's bias is only in columns 5 to 14. So this and the next parameter (X2) are used to specify the range in the X direction to be used in bias detection.

(x2) [int]

See above.

(out_format) [string, allowed values = "calwp2|general|detail"]

Output format. If out_format = "calwp2", it prints out the message used in the pipeline task calwp2. If out_format = "general", it also print out the file name and an estimate of where the jump occurs. If out_format = "detail", it prints out more detailed information.

EXAMPLES

1. Detect bias jump in WFPC2 images. Compare all subsections.

wf> bjdetect *.x0h 0.09 8 7 x1=5 x2=14

REFERENCES

SEE ALSO