A photosensitive apparatus, such as scanner, includes a plurality of pixels, each pixel having associated therewith a set of photosensors, each photosensor filtered to record a primary color. The photosensors are exposed to light of each primary color separately, thereby deriving test signals. A cross-color correction factor for the pixel is derived from the test signals. The cross-color correction factor is used in processing signals output from the pixel when an image is being recorded, so as to isolate the effects of signal crosstalk between closely-spaced photosensors of different colors.