Patent ID: 7751734

Claim:
A method of calibrating a marking engine that includes a photoreceptor transfer device having at least a first area on a surface of the photoreceptor transfer device, the at least first area receiving at least one color of marking material that is a portion of an image, the photoreceptor transfer device conveying the marking material to at least one of another transfer device or an output substrate, the method comprising: disposing at least one toned patch in a second area of the photoreceptor transfer device, the second area being located on the surface of the photoreceptor transfer device; and illuminating the disposed toned patch or image; measuring a reflectance value for the toned patch or image to obtain a measured reflectance value for the toned patch or image in response to the illumination; and based on the measured reflectance value, performing a color calibration for use in a marking operation, wherein illuminating the at least one toned patch or image comprises illuminating the at least one toned patch or image with an illumination wavelength outside the photo response range of the photoreceptor transfer device.