A marking engine forms one or more toned patches and/or images on a
photoreceptor transfer device such as a photoreceptor belt or drum,
either within or outside a main image area. A sensor illuminates the
tones patches and/or images on the photoreceptor transfer device using
wavelengths outside the photo response range of the photoreceptor
transfer device, thereby allowing reflectance values for each toned patch
and/or image to be measured without generating ghost images on the
photoreceptor transfer device. The sensor supports collection of measured
reflectance values from single-color, mixed-color; and multi-separation
image-on-image toned patches and/or images directly from the
photoreceptor transfer device at rates as high as one or more times per
revolution of the photoreceptor transfer device. The measured reflectance
values may be used to generate and/or update color stabilization tone
reproduction curves.