YORIC is the piece of software used by IPAC's FRESCO and HIRES IRAS data processors to create an image, and, in the case of HIRES, to perform resolution enhancement on the data. YORIC uses the Maximum Correlation Method (MCM) algorithm (H.H. Aumann, J.W. Fowler and M. Melnyk, 1990,AJ,99, 1674).

The MCM is an image-reconstruction algorithm rather than a deconvolution algorithm. It operates on the data in detector scan form, not image form. It iteratively builds a model of the sky which produces simulated IRAS detector data which are maximally consistent with the actual scan data.

YORIC begins by using modeled detector response functions to "observe" a flat sky, in the same way IRAS actually observed the target. The simulated scan data from the blank sky are compared to the actual scan data for each detector. Correction factors are then computed by dividing the actual sample detector flux by this estimated flux. The original flat field pixels are then multiplied by a weighted average of the corresponding correction factors in order to obtain a new estimated flux.

The initial iteration of this procedure produces a response-weighted coadd. This is the FRESCO product. For HIRES, the process is then iterated, using the last "corrected" image to replace the flat field as a progressively better model of the actual infrared sky. The improved model sky is then "observed" with the model detectors and a better model sky is produced.

YORIC is further documented in the YORIC Software Design Specification (J.W. Fowler and M. Melnyk, 1989, IPAC, Pasadena).