adder -- weighted stacking of images
adder [flags] images
The task adder combines a set of input images. If the weight-flag is used the output is a weighted sum with weights taken from the
header. If not the output is an equally weighted sum. If the wep-flag is set, the task creates also an output errorframe using input
errorframes for each of the input images. The functionality of the task is very simple. The nondomima-flag (nondomerr-flag)
regulates, if a nonvalid pixel in one of the input images (one of the input errorframes) is dominant or not, i.e. if it results in a zero value in
the output image (output errorframe) or if it is just not taken into account and the pixel value in the output image (output errorframe) is
calculated using the values of the remaining input images (input errorframes).
For the input images, all pixels with value "0" are considered as nonvalid. If wep is used all pixels with the value "-1" in the input errorframe are considerd to be saturated pixels. Saturated pixels are always dominant, so if there is a pixel with value "-1" in one or more of the input errorframes, this pixel will be set to "0" in the output image and to "-1" in the output errorframe, no matter if the pixel is saturated or not in the other input errorframes. In the errorframes all pixels with a negative value other than "-1" are considered to be nonvalid. If there is a nonvalid pixel in an input errorframe, the pixel is also marked as nonvalid in the corresponding input image and vice versa.
In order to calculate an average julian date and a total intagration time the julian-flag has to be set. The keywords JUL-DATE and EXPTIME have to exist in the header of all the input images. If the absolut-flag is set, the absolut pixel values of the input images are combined.
adder -j -d -b -w -e stars_*.fits