Abstract: Method for shading one of a first plurality of sensing elements of an optical sensor. High-reflectivity and low-reflectivity reference values of the output signal of each of a second plurality of sensing elements of the sensor are obtained. An average or nominal high-reflectivity value of the high-reflectivity reference values for each sensing element of the second plurality is calculated. An average or nominal low-reflectivity value of the low-reflectivity reference values for each sensing element of the second plurality is calculated. An offset value for one of the sensing elements of the first plurality is calculated using at least the average or nominal high-reflectivity values and the average or nominal low-reflectivity values. The one sensing element of the first plurality is calibrated using at least the calculated offset value. In one example, the first plurality and the second plurality are identical.

Abstract: A method and apparatus for mapping a color space to a colorant space. The method comprises an operation for selecting a color value from a color space, identifying a color value in a colorant space that minimizes a function parameterized to the color value selected from the color space, and associating the color value selected from the color space with the color value identified in the colorant space. An apparatus for mapping a color space to a colorant space comprises a processing unit, a memory unit coupled to the processing unit, and a software means. The software means is operative on the processing unit for minimizing an error function of a differentiable function capable of mapping a colorant space to a color space to obtain a function capable of mapping the color space to the colorant space. The error function includes a color difference error.

Abstract: Image data is corrected in a device or system using multiple halftones by predicting a second tone transfer curve corresponding to a second halftone based on a first tone transfer curve corresponding to a first halftone. First and second tone transfer curve compensate for application of the first halftone and the second halftone, respectively, to image data. The first tone transfer curve is determined by measuring image data halftoned with the first halftone and developing a first tone transfer curve that linearizes the measured image data. To produce the second tone transfer response curve, measured values of image data halftoned with the second halftone are estimated based on a predetermined relationship between the measured image data that is halftoned with the first halftone and image data that is halftoned with the second halftone. The second tone transfer curve is then developed as the curve that linearizes the estimated measured values of image data halftoned with the second halftone.