Pixel Beam Parameter Determination in Image Sensors
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Solution Overview
Problem
There is a need to determine the parameters defining a pixel beam associated with a pixel on an image sensor in an optical device, such as a conventional camera or light field acquisition camera, which are essential for understanding the volume of light rays and their interaction with the optical system, but existing methods lack an efficient calibration process to accurately obtain these parameters.
Innovation Solution
A method is developed to determine the direction of the chief ray and parameters of the pixel beam by illuminating specific pixels on a screen, verifying detection by the image sensor, and using a subset of pixels to calculate the parameters, which involves classical intrinsic/extrinsic calibration and modifying the optical system features to account for distortion, utilizing software and hardware components to execute these steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classical intrinsic/extrinsic calibration methods are used to determine pixel beam parameters, then the calibration process can be performed with standard procedures, but the accuracy of pixel beam parameter determination is insufficient due to optical distortions and field curvatures
Solution Approach 1:
The patent modifies the features of the optical system by applying distortion corrections and field curvature adjustments to the determined parameters. This involves changing the parameter set to account for optical imperfections, thereby improving measurement accuracy while maintaining calibration reliability under distorted conditions
Solution Approach 2:
The patent replaces pure geometric calibration with a hybrid approach that incorporates optical physics models. By substituting simple geometric projections with physics-based optical models that account for lens distortions and field curvatures, the system achieves higher accuracy in pixel beam parameter determination
2Measurement precision
If a hyperboloid model is used to represent pixel beams in plenoptic systems, then the representation is compatible with étendue conservation and pixel sensitivity, but the calibration process becomes more complex compared to simple cone models
Solution Approach 1:
The patent segments the calibration process into distinct stages: initial geometric calibration using standard methods, followed by refinement stages that incorporate hyperboloid modeling and distortion corrections. This segmentation allows the system to benefit from the simplicity of initial calibration while progressively achieving higher accuracy through the more complex hyperboloid model
Solution Approach 2:
The patent applies partial hyperboloid modeling where the full complexity of the hyperboloid representation is used only where necessary (in the fundamental region where pixel sensitivity is significant), while simpler models suffice in other regions. This partial application reduces overall calibration complexity while maintaining accuracy where it matters most
Data Source
AI summary
A method for obtaining, for at least one pixel of an image sensor comprised in an optical device, parameters defining a pixel beam is described. The method is remarkable in that it includes determining a direction of a chief ray associated with at least one pixel of the image sensor from the features of an optical system associated with the optical device, determining a set of pixels formed in a screen of a display device, the set of pixels comprising at least one pixel close to a point corresponding to an intersection of the chief ray and the screen, and the set of pixels comprising only pixels which are detected by the at least one pixel of the image sensor, when they are illuminated.