Image Processing Apparatus Dynamic Range Contrast Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image processing techniques fail to effectively improve image quality when a wide dynamic range image is displayed on a display apparatus with a narrow dynamic range, often resulting in blown-out highlights and blocked-up shadows due to inadequate contrast correction.
Innovation Solution
An image processing apparatus that acquires gradation values of neighborhood pixels and uses conversion information to determine a pixel's gradation value on a converted image, performing contrast correction by expanding the dynamic range through specific tone curve adjustments in light, intermediate, and dark gradation portions, thereby enhancing contrast without directly improving the display apparatus's dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If tone curve correction processing is performed to raise contrast in narrow dynamic range displays, then contrast is improved, but blown-out highlights and blocked-up shadows occur
Solution Approach 1:
The patent applies different tone curve correction strategies to different luminance regions (highlight, midtone, shadow portions) rather than uniform correction. By analyzing histogram distributions and applying region-specific gamma corrections, the patent improves contrast in each region independently, preventing over-correction in highlights and shadows while maintaining detail preservation.
Solution Approach 2:
The patent performs multiple passes of tone curve correction with progressively stronger effects. It first applies a base correction, then iteratively enhances contrast in regions that benefit from additional correction while monitoring for clipping. This partial action approach allows gradual improvement without immediately causing blown-out highlights or blocked-up shadows.
2Illumination intensity
If gamma correction is performed to raise contrast according to ambient illuminance, then contrast is improved, but blown-out highlights and blocked-up shadows occur
Solution Approach 1:
The patent dynamically adjusts gamma correction parameters based on real-time analysis of the image histogram and ambient illuminance conditions. Rather than applying a fixed gamma curve, it modifies correction strength and characteristics according to the specific luminance distribution of each image and environmental conditions, preventing uniform over-correction that causes highlights and shadows to clip.
Solution Approach 2:
The patent implements a feedback mechanism where each tone curve correction pass analyzes the results of previous corrections. It monitors histogram shifts and luminance distribution changes, then adjusts subsequent correction parameters accordingly. This feedback loop prevents accumulation of correction effects that would lead to blown-out highlights and blocked-up shadows.
3Manufacturing precision
If unsharp-mask coefficient is increased to improve sharpness, then sharpness is improved, but overshoot in lightest portion or undershoot in darkest portion occurs
Solution Approach 1:
The patent applies different unsharp-mask coefficients to different luminance regions of the image. Rather than using a uniform coefficient across all pixels, it analyzes local luminance characteristics and applies stronger sharpening to midtone regions while reducing or eliminating sharpening in highlight and shadow portions. This prevents overshoot in lightest portions and undershoot in darkest portions while maintaining sharpness where beneficial.
Data Source
AI summary
Image processing apparatuses, methods and storage mediums for use therewith are provided herein. At least one image processing apparatus includes, a first acquisition unit configured to, in order to generate a converted image having a narrower dynamic range than an input image, acquire gradation values of a plurality of neighborhood pixels positioned in a predetermined range from a processing target pixel of the input image, a second acquisition unit configured to acquire conversion information from a holding unit holding the conversion information used to generate the converted image having a narrower dynamic range than the input image, and a determination unit configured to determine a gradation value of a pixel on the converted image corresponding to the processing target pixel by using the gradation values of the plurality of neighborhood pixels acquired by the first acquisition unit and the conversion information acquired by the second acquisition unit.