System and method of generating color correction matrix for an image sensor
AssigneeHimax Imaging Limited
InventorYang Wu
Life of this patent
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Abstract
A system and method of generating a color correction matrix (CCM) for an image sensor are disclosed. Quantum efficiency (QE) spectra of pixels of the image sensor illuminated by a physical light source are measured. Subsequently, color values of the image sensor and color values in a predetermined color space are determined according to the QE spectra and predetermined reference data essential for deriving the color values. Finally, the CCM for the image sensor is generated by applying a fitting algorithm on the color values of the image sensor and the color values in the predetermined color space.
Claims16
A system for generating a color correction matrix (CCM) for an image sensor, comprising:
- a quantum efficiency (QE) measurement device constructed to generate QE spectra of the image sensor illuminated by a physical light source;
- a unit configured to compute color values and generate color values for the image sensor and ideal color values according to the generated QE spectra and predetermined reference data essential for deriving the color values;
- and
- a fitting unit arranged to generate the CCM for the image sensor;
- wherein the predetermined reference data include one or more of acquired predetermined color matching function (CMF), acquired power spectral density (PSD) of illumination and acquired reflectance spectra of predetermined color patches;
- and
- wherein the computing unit is configured to perform the following:
- determining CMF of the image sensor according to the QE spectra;
- acquiring the predetermined CMF;
- acquiring the PSD of illumination;
- determining white balanced CMF according to the PSD of illumination and the CMF of the image sensor;
- determining white balanced predetermined CMF according to the PSD of illumination and, the predetermined CMF;
- determining reflected light PSD from color patches according to the PSD of illumination and the acquired reflectance spectra of predetermined color patches;
- determining the color values of the image sensor according to the reflected light PSD from color patches and the white balanced CMF;
- and
- determining the color values in a predetermined color space according to the reflected light PSD from color patches and the white balanced predetermined CMF.
A method of generating a color correction matrix (CCM) for an image sensor, comprising:
- a computer for carrying out the steps of
- measuring quantum efficiency (QE) spectra of pixels of the image sensor illuminated by a physical light source;
- determining color values of the image sensor and color values in a predetermined color space according to the QE spectra and predetermined reference data essential for deriving the color values;
- and
- generating the CCM for the image sensor by applying a fitting algorithm on the color values of the image sensor and the color values in the predetermined color space;
- wherein the predetermined reference data include one or more of acquired predetermined color matching function (CMF), acquired power spectral density (PSD) of illumination and acquired reflectance spectra of redetermined color patches;
- and
- wherein the step of determining the color values comprises the following:
- determining CMF of the image sensor according to the QE spectra;
- acquiring the predetermined CMF;
- acquiring the PSD of illumination;
- determining white balanced CMF according to the PSD of illumination and the CMF of the image sensor;
- determining white balanced redetermined CMF according to the PSD of illumination and the predetermined CMF;
- determining reflected light PSD from color patches according to the PSD of illumination and the acquired reflectance spectra of predetermined color patches;
- determining the color values of the image sensor according to the reflected light PSD from color patches and the white balanced CMF;
- and
- determining the color values in a predetermined color space according to the reflected light PSD from color patches and the white balanced predetermined CMF.
Dependencies are inferred from the claim text.