Colorimetric imaging system

An imaging system that accurately obtains the color of a plurality of points in a scene when the scene is lit by a source of illumination, comprising:

• an imaging detector,
• imaging optics that receive light from the scene and direct it to the detector,
• a tunable filter that is disposed at one of a position between the source of illumination and the scene, a position between the scene and the imaging optics, and a position between the imaging optics and the detector, said tunable filter responsive to applied electrical signals that filters the spectrum of light passing therethrough,
• a control circuit for acquiring and storing a plurality of images from the detector while the filter expresses a plurality of predetermined filter response functions in response to applied electrical signals, and calculating the color at the plurality of points in the scene from the stored images, expressed in terms of a predefined color space,
• wherein the filter response functions have substantial transmission at a plurality of wavelengths;
• the color space comprises linear combinations of the colorimetric functions X, Y, and Z;
• and the detector and at least one of the filter response functions achieve overall spectral responses that are approximately proportional to one of the three colorimetric functions, X, Y, and Z.

The method of obtaining the colorimetric value of a plurality of points in a scene when the scene is lit by a source of illumination, comprising the steps of:

• receiving light from the scene and directing the received light to an imaging detector by use of imaging optics,
• filtering the light from the source of illumination or from the scene by use of a tunable filter capable of expressing a plurality of spectral response functions in response to applied electrical signals, wherein said tunable filter is disposed at one of a position between the source of illumination and the scene, a position between the scene and the imaging optics, and a position between the imaging optics and the detector,
• exposing the detector to light filtered by the tunable filter to obtain a plurality of images while the filter expresses a plurality of predetermined filter response functions in response to applied electrical signals, wherein each of the filter response functions has substantial transmission at a plurality of wavelengths, and
• determining the colorimetric value of the plurality of points in the scene from the plurality of images.