TOF Depth Sensor Saturation Correction via Adaptive Integration
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Solution Overview
Problem
Time of flight (TOF) sensors experience accuracy errors in depth image generation due to saturation issues, particularly with objects of bright colors like red, leading to distorted depth data.
Innovation Solution
An image processing apparatus and method that divides the integration time into two sections with different scales, using a lookup table to determine these sections based on the object's color index, and measures charge quantities in each section to generate a depth image, either using the smallest scale section's charge if saturation occurs or the sum of both sections' charges if it does not.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration time is increased to improve depth measurement sensitivity, then the measurement precision is improved, but saturation occurs in bright-colored objects causing depth data distortion
Solution Approach 1:
The integration time is divided into multiple sections, with different integration times assigned to different color ranges. Bright-colored objects use a shorter integration time to prevent saturation, while dark-colored objects use a longer integration time to improve sensitivity. This segmentation resolves the contradiction by allowing each object type to operate at its optimal integration time without affecting others.
Solution Approach 2:
The integration time parameter is dynamically changed based on the color information of the object. By adjusting the integration time according to the object's reflectance characteristics, the system maintains measurement precision for dark objects while preventing saturation for bright objects, thus resolving the contradiction between sensitivity and reliability.
2Device complexity
If a single integration time is used for all objects, then the device complexity is reduced, but depth data accuracy deteriorates for bright-colored objects
Solution Approach 1:
Different integration times are applied to different color ranges based on their specific needs. Bright-colored objects receive a shorter integration time while dark-colored objects receive a longer integration time. This local quality approach maintains high measurement precision for each object type without requiring complex dynamic adjustment mechanisms.
Solution Approach 2:
The system pre-defines multiple integration time values corresponding to different color ranges and stores them in a lookup table. During operation, the appropriate integration time is selected based on the object's color information, avoiding the need for complex real-time calculations while maintaining high depth data accuracy.
3Reliability
If the integration time is shortened to prevent saturation in bright objects, then the reliability is improved, but the sensitivity for dark-colored objects deteriorates
Solution Approach 1:
The integration time parameter is adjusted based on the object's color characteristics. Bright-colored objects use a shorter integration time to prevent saturation, while dark-colored objects use a longer integration time to maintain sensitivity. This parameter change strategy resolves the contradiction by optimizing the integration time for each object type.
Solution Approach 2:
Different integration time settings are applied locally to different color ranges. Bright objects operate with shorter integration times for reliability, while dark objects operate with longer integration times for sensitivity. This local quality approach ensures both saturation prevention and high measurement precision without requiring a single compromise setting.
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
This approach reduces errors in depth data by minimizing saturation effects across various colors, ensuring accurate depth image generation without compromising sensitivity or increasing integration time.
Implementation Method 1
a light receiver to transduce a light reflected from an object onto an electron corresponding to an intensity of the light
Implementation Method 2
The TOF scheme refers to a scheme of measuring a period of time taken for a light to be reflected and returned, after being radiated to an object using a TOF sensor
Data Source
AI summary
An image processing apparatus includes a light receiver to transduce a light reflected from an object into an electron corresponding to an intensity of the light, a measurer to measure quantities of charge on the electron with respect to at least two different divided time sections of an integration time section for acquiring a depth image, and an image generator to generate a depth image using at least one of the at least two measured quantities of charge on the electron.