Dynamic Tone-Curve Correction for Vehicle Camera Luminance
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Solution Overview
Problem
Existing image processing techniques for luminance correction in cameras use fixed tone-curves, making it impossible to acquire appropriate corrected images based on varying imaging scenes.
Innovation Solution
An image processing apparatus that generates a corrective tone-curve based on the histogram of captured images, combining linear, logarithmic, and flattening tone-curves to perform luminance correction, allowing for scene-dependent image correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed tone-curve is used for luminance correction, then the correction process is simple and fast, but the corrected images are not appropriate for varying imaging scenes
Solution Approach 1:
The patent implements dynamic tone-curve selection by automatically determining the imaging scene type (e.g., night scene, daytime scene, tunnel scene) and selecting or generating an appropriate tone-curve for each scene. This replaces the static fixed tone-curve approach with a dynamic adaptation mechanism that adjusts the correction characteristics based on actual imaging conditions, thereby resolving the contradiction between processing simplicity and scene adaptability.
Solution Approach 2:
The patent changes the parameters of the tone-curve based on the detected imaging scene. Different scene types have different optimal tone-curve parameters (e.g., gamma values, contrast curves), and the system adjusts these parameters dynamically to match the imaging conditions, enabling appropriate luminance correction for each scene while maintaining automated processing.
2Adaptability or versatility
If scene-dependent tone-curves are generated dynamically, then appropriate corrected images are achieved for different imaging scenes, but the processing complexity increases
Solution Approach 1:
The patent performs preliminary scene analysis by generating histograms from the captured image data and determining the imaging scene type before applying the tone-curve correction. This preliminary classification step enables the system to select the most appropriate pre-defined or dynamically generated tone-curve, avoiding the need for complex real-time optimization during the actual correction process.
Solution Approach 2:
The patent uses histogram data as a representative copy or summary of the image content to determine the imaging scene. Instead of analyzing the entire image in detail, the system processes the compressed histogram representation to identify scene characteristics, reducing computational complexity while maintaining accurate scene-dependent correction capabilities.
Data Source
AI summary
In an image processing apparatus, an image acquirer is configured to acquire a captured image from a camera mounted to a vehicle. A histogram generator is configured to generate a histogram representing a relationship between a luminance and a pixel count of the captured image. The pixel count is a number of pixels in the captured image. An image corrector is configured to generate a corrective tone-curve for correcting the relationship between the luminance and the pixel count of the captured image based on the histogram of the captured image, and correct the captured image using the corrective tone-curve to generate a corrected image. The corrective tone-curve is a tone-curve representing a relationship between input and output values of luminance.