Photoelectric Tone Mapping for Fast High-Luminance Recognition
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Solution Overview
Problem
Conventional image tone compression methods, particularly for vehicle-mounted cameras, often set high compression ratios for high luminance regions, leading to decreased tone information and recognition precision in these areas, which is problematic for rapid image recognition needed in autonomous driving systems.
Innovation Solution
A photoelectric conversion device with pixels that generate pulses based on photon reception frequency, using counters to control accumulation periods and generate mapping parameters for tone mapping, allowing for differential processing of image signals across multiple accumulation periods to maintain recognition precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high compression ratio is applied to high luminance regions for tone mapping, then transmission band efficiency is improved, but tone information and recognition precision deteriorate
Solution Approach 1:
The patent applies different compression ratios to different luminance regions dynamically. High compression is applied to low luminance regions where human vision is less sensitive, while low or no compression is applied to high luminance regions where tone information is critical for recognition. This local differentiation resolves the contradiction by preserving recognition precision in key areas while maintaining overall transmission efficiency.
Solution Approach 2:
The patent dynamically adjusts compression ratios based on real-time image content analysis. The system evaluates the luminance distribution and recognition needs of each frame, then adapts the compression parameters accordingly. This dynamic adjustment allows the system to optimize between transmission efficiency and recognition precision according to changing scene requirements.
2Measurement precision
If accumulation period is extended to improve signal accuracy, then measurement precision is improved, but processing time and system response speed deteriorate
Solution Approach 1:
The patent segments the accumulation period into multiple sub-periods and processes image signals at different stages. Instead of waiting for a single long accumulation period to complete, the system performs tone mapping and recognition processing on partial accumulation results, then refines them as accumulation continues. This segmentation allows parallel processing and reduces the critical path for system response.
Solution Approach 2:
The patent performs preliminary tone mapping and feature extraction during the accumulation period before full signal acquisition is complete. By conducting preliminary processing actions in parallel with ongoing accumulation, the system reduces the total processing time while maintaining signal accuracy, as the preliminary results can be used for timely recognition decisions.
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 enables rapid image recognition by allowing processing during shorter accumulation periods while maintaining tone information, reducing delays and preserving recognition precision, especially in dynamic environments.
Implementation Method 1
a sensor unit that generates a pulse at a frequency corresponding to a photon reception frequency
Data Source
AI summary
A photoelectric conversion device has a plurality of pixels each of which is configured to include a sensor unit that generates a pulse at a frequency corresponding to a photon reception frequency, and a counter that counts a number of the pulses. The plurality of pixels are controlled such that a signal is generated based on a difference between count values for the counter between a start time and an end time for a plurality of different accumulation periods within a full frame period, and such that an image signal that is generated during a first accumulation period is output between a time from an end of the first accumulation period until an end of a second accumulation period. In addition, the photoelectric conversion device generates a mapping parameter and performs tone mapping processing on the image signal using the mapping parameter.