fmrgmsk -- Merge 2 or more input FITS mask images and create a single output mask image file.
This task merges up to 100 input MASK files into an output mask. Each mask consists of a 2-dimensional image whose pixel values flag the corresponding pixels in another image file. Typically the mask image will only contain 1's and 0's, but in principle a mask file could contain pixels with any arbitrary data value. The output mask is produced by either logically combining the input masks using an OR, AND, or XOR operation or by numerically ADDing or SUBtracting the actual values. The logical state of each pixel is determined by whether the pixel = zero or not. For example if 3 masks are merged with the OR operation, then the output mask will contain a 1 every pixel that is not equal to zero in any of the input masks. If the AND operation is specified, then the output mask will contain 1's only in those pixels that are non-zero in ALL the input masks.
All the input masks must have the same dimensionality. There is no size limitation on the image. All keywords from the first input image are copied to the output mask.
1. Merge the mask1.fits and mask2.fits files with a logical OR operation and write the output to the file outmask.fits:
ft> fmrgmsk mask1.fits mask2.fits mask3.fits ops=OR