Variable forgetting factors in Kalman filtering

Kodak Signature Color Proofing System is a machine that tests the color texture of a picture for separation of its components into magenta, cian, yellow and black. Actually the first three determine the color and the black component determines the brightness. We make an intuitive judgement on the color components at each pixel and feed the corresponding instructions to the machine. The machine then produces a print. If the print agrees with the original picture then the input information is stored away and is later transferred to the appropriate media where the picture is to appear in print (magazine, newspaper, book, etc.). If the print does not agree satisfactorily with the original picture then additional adjustments need to be made in determining the separation. The actual printing of the test prints is accomplished with toner fluid of the four colors mentioned above by application of electric field around the “printing station” within the machine. New toner is added typically after every 50 prints. The entire process must be assured of a high degree of consistency. It is inevitable however that there will be random variations in the moving parts of the machine, in the start-up conditions, and in the consistency of the toner. The goal of the manufacturer of the machine and of the machine operator is to minimize these variabilities.