Spectral estimation method, system and reference target design method

A method for estimating spectral data on a selected one of a set of at least three spectral information types, the method comprising:

• obtaining a ranking order for a plurality of sensor responses produced by an imager, each of the plurality of spectral responses being produced from a reference target in the scene;
• obtaining, from an alternate source, data on at least two of the other spectral information types;
• and,
• determining a set of constraints, the set including, for each sequential pair combination of sensor responses when taken in said ranking order, a constraint determined in dependence on the ranking and on the other two or more spectral information types for the respective sensor responses;
• in dependence on the ranking order and on the set of constraints, determining said spectral data that optimally satisfies said constraints.

A system for estimating spectral data on a selected one of three spectral information types comprising:

• illumination of a scene;
• spectral sensitivity of an imager imaging the scene;
• and,
• reflectance of a surface in the scene,
• the system comprising:
• an imager operable to provide sensor responses;
• a ranking component arranged to obtain a ranking order for a plurality of sensor responses produced by the imager, each of the plurality of sensor responses being produced from a reference target in the scene;
• a processing component arranged to execute computer program code to:
• receive the ranking order and data from an alternate source on the other two spectral information types,
• determine a set of constraints, the set including, for each sequential pair combination of sensor responses when taken in said ranking order, a constraint determined in dependence on the ranking and on the other two spectral information types for the respective sensor responses, and
• in dependence on the ranking order and on the set of constraints, determine said spectral data that optimally satisfies said constraints.