Image Processing Apparatus Luminance Gradation Correction
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Solution Overview
Problem
Existing image processing techniques fail to effectively enhance the contrast of images with a large number of pixels distributed in both high and low luminance ranges, leading to inadequate visibility and image quality.
Innovation Solution
An image processing apparatus and method that acquires luminance distribution data to generate control information for correcting luminance gradation, using tone curves to adjust luminance levels and enhance contrast, particularly in the medium-luminance region, by determining control points on multiple tone curves based on histogram analysis and correction intensity parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional luminance gradation correction is applied to images with pixels distributed in high and low luminance ranges, then processing simplicity is maintained, but contrast enhancement is insufficient especially in medium-luminance regions
Solution Approach 1:
The patent segments the luminance distribution into multiple ranges (high luminance range, medium luminance range, low luminance range) and applies different correction strategies to each segment. By dividing the histogram analysis into distinct regions and generating separate control information for each, the system achieves precise contrast enhancement in medium-luminance regions while maintaining overall processing efficiency.
2Measurement precision
If strong luminance gradation correction is applied to enhance contrast, then visibility is improved, but unnatural image quality occurs due to excessive contrast enhancement
Solution Approach 1:
The patent dynamically adjusts correction parameters based on the analyzed luminance distribution characteristics. By changing the correction strength parameter according to the specific image content and luminance histogram shape, the system enhances visibility where needed while preventing unnatural artifacts. The correction amount is adaptively modified to match the actual distribution of pixels in different luminance ranges.
Solution Approach 2:
The system performs histogram analysis to detect the actual luminance distribution, uses this feedback information to determine appropriate correction control information, and applies corrections that are tailored to the specific image characteristics. This closed-loop approach ensures that contrast enhancement improves visibility without producing unnatural results.
3Device complexity
If single-tone-curve correction is used, then processing complexity is reduced, but adaptability to different luminance distributions is insufficient
Solution Approach 1:
The patent transitions from a static single-tone-curve approach to a dynamic multi-curve approach where multiple tone curves are generated based on the detected luminance distribution. The system adaptively creates different correction curves for different luminance ranges (high, medium, low) and selects or combines them based on the actual image characteristics, providing versatile adaptation while maintaining reasonable processing complexity.
Data Source
AI summary
An image processing apparatus comprises a first acquisition unit configured to acquire, based on a luminance distribution in an input image, first control information for controlling characteristics of luminance gradation correction to be applied on the input image, a second acquisition unit configured to acquire, based on the first control information, second control information for controlling characteristics of luminance gradation correction to be applied on the input image, and a correction unit configured to correct luminance gradation of the input image based on the second control information.