Image Processing Apparatus Optimizing Pattern Light Brightness and Exposure
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Solution Overview
Problem
Existing distance measurement techniques face challenges in accurately specifying the position of pattern light and performing high-accuracy distance measurement due to variations in reflectance, orientation, and luminance gradation values, especially when dealing with glossy surfaces and varying distances or positions of target objects, leading to potential saturation, shadow detail loss, and decreased measurement accuracy.
Innovation Solution
An image processing apparatus and method that uses a space encoding method with a projection unit and image capturing unit to control pattern light brightness and exposure amount, employing a 4-bit gray code and triangulation principle to accurately specify pattern positions and measure distances, while adjusting parameters to optimize luminance gradation values and reduce noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brightness adjustment and exposure amount adjustment are performed to specify pattern light position, then position specifying capability is improved, but pattern position specifying accuracy drops when adjustments are improper or insufficient
Solution Approach 1:
The patent applies preliminary action by capturing a preliminary image before distance measurement to determine appropriate brightness and exposure amount settings. This preliminary adjustment ensures that subsequent pattern light position specification occurs under optimized conditions, preventing saturation and shadow detail loss while maintaining high specifying accuracy.
Solution Approach 2:
The patent uses feedback by analyzing the luminance gradation values from the preliminary captured image to automatically determine optimal brightness and exposure settings. The system feeds back this information to adjust the imaging conditions, ensuring that pattern light positions can be specified with high accuracy without manual intervention.
2Ease of manufacture
If maximum reflectance is determined based on uniform pattern light image, then brightness and exposure can be determined, but influence of contrast decrease from blur is not taken into account
Solution Approach 1:
The patent captures a preliminary image under actual measurement conditions (with the specific pattern light used for position specification) before performing distance measurement. This preliminary action allows the system to determine brightness and exposure settings that account for the actual contrast and blur characteristics of the pattern light, rather than using generic settings from uniform pattern light images.
3Ease of operation
If maximum reflectance and exposure amount are determined based on maximum value of image luminance gradation value, then adjustment can be made, but no appropriate adjustment is performed when target object is highly glossy due to halation
Solution Approach 1:
The patent analyzes the actual luminance gradation distribution from a preliminary captured image to determine appropriate brightness and exposure settings. This feedback mechanism allows the system to detect halation effects on glossy surfaces and adjust settings accordingly, rather than simply using the maximum luminance value which may be skewed by specular reflections.
4Measurement precision
If exposure amount is adjusted using histogram peaks of projection light and background light, then exposure can be optimized, but peaks cannot be discriminated when background light luminance is high and almost equal to projection light
Solution Approach 1:
The patent uses feedback from the actual captured image luminance distribution to determine appropriate exposure settings. Rather than relying on histogram peak discrimination which fails when background light is too bright, the system analyzes the overall luminance gradation values and adjusts exposure based on this feedback, ensuring adequate contrast for pattern light detection even in high background light conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables reliable and high-accuracy specification of pattern light positions and distance measurement, even under varying conditions, by optimizing brightness and exposure settings, thereby improving measurement precision and reducing errors caused by noise and surface characteristics.
Implementation Method 1
There is known a method of projecting pattern light to a target object using a projection unit such as a projector, and specifying the position of the pattern light from a captured image obtained by capturing the target object by an image capturing unit such as a camera
Implementation Method 2
capturing the target object by an image capturing unit such as a camera, thereby measuring a distance
Data Source
Figure 1
Figure 2A~2G
Figure 3
AI summary
A captured image obtained by capturing, by an image capturing unit, a target object to which a pattern has been projected is acquired. At least either of a first parameter for controlling brightness of the pattern projected from a projection unit configured to project the pattern, and a second parameter for controlling the exposure amount of the image capturing unit is adjusted in accordance with the luminance value of the pattern in the acquired captured image.