What is RegiStar?
RegiStar is an image alignment, or registration, program that was designed to work specifically with astronomical images. RegiStar finds the stars in an image, and uses their positions to align this image to another image or group of images. RegiStar uses a sophisticated matching algorithm that allows images at different scales and orientations to be registered. RegiStar automatically corrects for geometric distortions including reflections, so it works on images taken with different optical systems. Also, it works on image pairs that have only a small overlap. RegiStar accurately registers most images that have at least a 1% overlap and at least 10 stars in common, even if they contain a large amount of noise such as hot pixels.
RegiStar requires no user input to complete a registration, other than the specification of the images. The matching and alignment are performed automatically without the input of any matching points or parameters.
RegiStar includes the capability of processing several images at once, in a batch. An entire directory of images can be registered using a single command, and several other commands can also handle multiple images.
RegiStar also includes some tools to assemble and manipulate images after they have been registered. These tools were designed specifically to automate tasks commonly done by digital astrophotographers, such as forming mosaics, forming tricolor images, and stacking exposures.
TIFF, JPEG, and FITS images are supported. RegiStar supports 8- and 16-bit depth internally, but will read higher depth FITS images.
RegiStar is not an image-editing program. It is designed to register and assemble images, and, except for the ability to calibrate one image to another, does not have any commands for adjusting brightness or contrast, removing flaws, or otherwise editing images. It is assumed that RegiStar will be used in conjunction with another program that has these capabilities. RegiStar is designed so that other programs can easily be used together with it.