NFRL registers two fingerprint images based on a pair of corresponding control-points. It uses this control-point pair of pixel locations within the images to translate and rotate the Moving image to the Fixed image. Runtime configuration parameters include:

* moving and fixed image data in 8-bits-per-pixel grayscale (preferable but not required)

* two-pairs of corresponding control points (pixel coordinates).

The fingerprint-image rigid-registration process is performed in two steps:

1. Translation of the Moving image to the Fixed image using the "first" pair of control-points (the unconstrained pair)

2. Rotation of the Moving image around the Fixed image control-point (the translation "target" location) based on the angle-difference determined by the "second" pair of control-points (the constrained pair).

Both final images, a few interim images, and registration metadata generated during the registration process are made available to the using software:

* Final registered Moving image

* Final registered Fixed image

* Registered, padded, overlaid image (colorized)

* Registered, padded, Moving image (grayscale)

* Padded, Fixed image (grayscale)

* Summed, registered, dilated overlaid image (the "blob")

* Process metadata available in both text and XML format.

The two Final images are registered. They are cropped to the region-of-interest that is the smallest area of "overlap" per the registration. Therefore, these two images have identical width and height which enables analysis using metrics like PSNR (Peak Signal to Noise Ratio).