Camera Calibration for Lens De-center Correction
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Solution Overview
Problem
The increasing pixel density in smartphone cameras leads to smaller sensor pixels, reducing light quantity and increasing noise, especially in low light conditions, which deteriorates image quality and introduces blur due to handshaking issues during longer exposure times.
Innovation Solution
A system and method for calibrating cameras that includes centering calibration data stored in memory to adjust the image recognition region of an image sensor, allowing for decenter correction between the optical axis of a lens and the image sensor's center, and includes a shaking detector to control lens calibration and reduce blur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pixel size of the sensor is reduced to increase the number of pixels, then the number of pixels is improved, but the light quantity received by the sensor is reduced and noise increases
Solution Approach 1:
The patent changes the parameter of pixel size from large to small to increase the number of pixels, which directly addresses the contradiction by accepting reduced light quantity per pixel in exchange for higher pixel density and improved resolution
2Illumination intensity
If the exposure time is increased to compensate for reduced light quantity, then the light quantity is improved, but handshaking blur increases
Solution Approach 1:
The patent performs preliminary calibration of the optical axis centering before actual photography. By pre-determining the deviation between the optical axis and sensor center, and applying this calibration data during image processing, the system can compensate for optical misalignment without requiring extended exposure times, thus avoiding handshaking blur while maintaining adequate light collection
3Ease of manufacture
If the optical axis of the lens is not centered on the image sensor, then manufacturing is easier, but image quality deteriorates due to decenter
Solution Approach 1:
The patent performs preliminary calibration to determine the deviation between the optical axis and sensor center during manufacturing. This calibration data is stored and applied during image processing to compensate for the misalignment, allowing easier manufacturing while maintaining image quality through software-based correction
4Illumination intensity
If the exposure time is extended to improve light collection, then the light quantity is improved, but noise increases due to handshaking
Solution Approach 1:
By performing preliminary optical axis calibration and storing the deviation data, the system enables accurate image processing without requiring extended exposure times. This preliminary action eliminates the need to trade image quality for light collection by using calibration-based correction instead of longer exposures
Data Source
AI summary
There is provided a system for calibrating a camera including: a memory storing centering calibration data reflecting a deviation of an optical axis of a lens; and an image signal processor determining an image recognition region of an image sensor based on the centering calibration data to process an image signal input from the image sensor.