Patent ID: 8525997

Claim:
An apparatus for measuring the color or reflectance of a sample comprising: a plurality of reference targets of known reflectance value, each reference target having a reflective surface, wherein, at all of a selected set of measurement wavelengths, at least one reference target reflects a greater fraction of light projected on its surface than at least one of the other reference targets; an activated variable intensity light source having a light output, configured to project light in the direction of one of the plurality of targets and the sample having a color characteristic to be measured; at least one color sensor positioned as a sample channel so as to receive light reflected from one of the plurality of targets and sample and output a measured color value; at least one reflectance sensor positioned as a reference channel so as to receive light reflected from a light division device prior to contact with one of the target or sample and output a reference value; and a processor configured to compare the output from the sample channel to the output of the reference channel and generate a computed measurement value that is substantially free of variations of the activated light source; the processor further configured to compare the known reflectance value of each of the plurality targets to the computed measurement value obtained from at least one of the reference targets and generate an adjustment value; the processor further configured to generate a computed measurement value of a sample and adjust the computed measurement value of the sample by the adjustment value and output the result.