Smartphone Camera Calibration Using Embedded Reference Patterns
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Solution Overview
Problem
Smart mobile devices lack the capability to accurately measure object dimensions, distances, and color/brightness levels in captured images without proper calibration, which limits their utility in applications requiring precise measurements.
Innovation Solution
Incorporating calibration patterns within the focus plane of the camera's field of view, such as two-dimensional bar codes or geometric patterns, that provide known characteristics, allowing the device to calibrate and measure dimensional, brightness, and color information of objects in the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration patterns are incorporated into the camera's field of view, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces calibration patterns as intermediary elements that mediate between the camera system and the measurement task. These patterns serve as reference objects that enable the camera to calculate real-world dimensions from image data without requiring complex hardware modifications. The calibration patterns act as a bridge that translates pixel measurements into physical measurements through known geometric relationships.
Solution Approach 2:
The patent uses two-dimensional bar codes and geometric patterns as simplified copies or representations of measurement references. Instead of requiring complex three-dimensional calibration objects, the system uses flat, two-dimensional patterns that can be easily captured by the camera. These patterns contain encoded information about their real-world dimensions, allowing the system to perform measurements by comparing image coordinates against the known pattern geometry.
2Measurement precision
If the camera captures images with higher digital resolution, then measurement precision is improved, but the difficulty of detecting and measuring calibration patterns increases
Solution Approach 1:
The patent employs calibration patterns with distinct color variations and high contrast characteristics. The patterns use specific color schemes that create strong visual differentiation between pattern elements and the background, making them easily detectable by the camera's image sensor. The color changes and contrast variations in the patterns help the detection algorithm identify pattern features even at high resolutions where individual pixels are numerous and fine details are prominent.
Solution Approach 2:
The patent transitions from considering only the two-dimensional image plane to incorporating the third dimension of known real-world dimensions. The calibration patterns have predetermined physical dimensions that provide a reference scale, allowing the system to convert two-dimensional image coordinates into three-dimensional real-world measurements. This dimensional reference resolves the complexity of high-resolution measurements by providing a known scale factor.
3Measurement precision
If calibration patterns are placed within the focus plane, then measurement accuracy is improved, but the adaptability of the system to different shooting distances is reduced
Solution Approach 1:
The patent implements a dynamic calibration approach where the system can adapt to different shooting distances by adjusting the calibration process rather than requiring fixed positioning. The calibration patterns can be captured at various distances, and the system dynamically calculates the appropriate scale factors and transformation matrices based on the actual capture conditions. This allows the measurement system to maintain accuracy across different ranges by adapting the calibration parameters to each specific shooting scenario.
Solution Approach 2:
The patent allows for changes in calibration parameters such as pattern size, distance, and orientation to accommodate different measurement scenarios. The system can adjust the effective calibration scale by changing the distance to the calibration pattern or by using patterns of different dimensions. These parameter changes enable the system to maintain measurement accuracy whether the target is close or far, flexible or rigid, by adapting the calibration settings to match the specific measurement requirements.
Data Source
AI summary
A digital image is captured. The captured digital image includes a calibration pattern. The calibration pattern includes displayed information about the calibration pattern. The displayed information is read to obtain calibration information about the captured digital image.