darksub: Scale and subtract a dark count image
Package: generic
Usage
darksub input output darkimage
Parameters
- input
- List of input images from which to subtract the dark count image.
- output
- List of output dark count subtracted images. The output images may be the same as the input images. The input and output image lists should contain the same number of images.
- darkimage
- Dark count image to be scaled and subtracted from the input images.
- exposure = ""
- Header parameter name from which to obtain the exposure times.
- pixtype = "1"
- The pixel datatype of the dark subtracted images. The default ("1") is the pixel datatype of the original image. The other choices are "short", "integer", "long", "real", and "double".
- verbose = yes
- Print log of operations performed.
Description
The dark count image is scaled by the ratio of the input image exposure to the dark count image exposure and subtracted from each of the input images. The exposures are obtained from the image headers under the specified name. The output images may have the same names as the input images. A temporary image is used for the scaled dark count image and the original image is not modified. The pixel datatype of the output images is specified by the parameter pixtype. The default ("1") uses the datatype of the input image. A log of the operations performed may be printed on the standard output when the verbose options is specified.
Note that this task can be used to subtract any type of image from a set of images in which the subtracted image must be scaled to a given exposure.
Examples
To subtract the dark count image 'dark' from obs1, obs2, and obs3:
cl> darksub obs1,obs2 obs1,obs2 dark exp="exposure"
Tue 18:50:56 08-Apr-86
obs1 = obs1 - 5.0049997336067 * dark
Tue 18:51:05 08-Apr-86
obs2 = obs2 - 5.009999733075 * dark
See also
imarith