Reprojects an image by resampling the integer pixel values onto the new output WCS.
This is a prototype CIAO tool to
reproject an image from one World Coordinate System (WCS) to another.
The existing reproject_image
tool does this by dividing the flux in each input pixel into each output
pixel. This is inappropriate when then input image has integer values
(eg X-ray counts). To preserve the Poisson nature of the data we need
to preserve integer counts so we need to resample the image.