Achieving color constancy across multiple cameras

ABSTRACT

With the advent of virtual spaces, there has arisen a need to integrate physical worlds with virtual spaces. This integration can be achieved with real-time 3D imaging using multiple stereo cameras at several geographically distributed locations followed by the fusion of information from multiple virtual and physical spaces. Systems that enable such information fusions are called tele-immersive. One of the key requirements of these systems is to produce rendered 3D videos of good quality by producing consistent colors. However, different cameras, even of the same type, can often exhibit radically different color responses. This leads to inconsistent appearance of color objects reconstructed at one location or rendered in a virtual space next to each other from reconstructions at multiple sites. This work presents a framework for addressing the problem of inter-camera color constancy. The approach to the problem is based on hardware and software-based color calibration using GretagMacbeth color charts. The developed solution optimizes the alignment of individual color channel response curves with the reference GretagMacbeth defined colors, and the proximity of color channel response curves from all cameras. The hardware-based calibration applies the Powell's search method to optimize response curves. The software-based calibration estimates parameters of a general polynomial transform and a neural network based transform. We report the results using this framework and are very encouraging.

REFERENCES

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INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.1 Multimedia Information Systems
          Subjects: Video (e.g., tape, disk, DVI)

General Terms:
Design, Experimentation

Keywords:
3D tele-immersion, color constancy