Image Processing Device for Gradation Correction

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Solution Overview

Problem

Conventional image-processing methods struggle to effectively correct the gradation of images with extreme brightness differences, often resulting in unnatural color balance and loss of detail in shadow areas, as they either over-brighten shadows or fail to enhance hidden gradational changes.

Innovation Solution

An image-processing device and method that extracts local fluctuations from an input image, generates a modulation signal, and applies level-compression to modulate the image, producing a gradation-corrected image by weighted addition of multiplied and offset-corrected components, allowing for flexible adjustment of weighted ratios in shadow and highlight areas to enhance hidden gradations while suppressing excessive brightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If gradation correction is applied to bright portions, then bright portion gradation is improved, but dark portions become blackened and lose detail

Engineering Contradiction:

Improvegradation correction accuracyVSAvoiddark portion detail

Core Design Contradiction:

Manufacturing precisionVSLoss of information

Solution Approach 1:

The patent applies different processing strategies to different regions of the image based on local characteristics. It identifies bright and dark portions separately and applies targeted corrections: bright portions receive gradation correction while dark portions receive brightness enhancement, avoiding the trade-off that affects the entire image uniformly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The image processing is divided into separate processing paths for bright portions and dark portions. The patent segments the image based on luminance thresholds and applies different correction algorithms to each segment, allowing independent optimization of gradation and brightness without mutual interference.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If brightness difference is reduced using low-contrast curve, then overall brightness uniformity is improved, but differences in brightness in middle gradation area are reduced

Engineering Contradiction:

Improvebrightness uniformityVSAvoidmiddle gradation brightness difference

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

Instead of applying a uniform low-contrast curve to the entire image, the patent applies local brightness adjustments based on region-specific characteristics. Bright portions use one correction strategy while dark and middle gradation areas use another, preserving local brightness differences where needed while achieving overall uniformity.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If shadow area brightness is increased, then shadow area gradation is enhanced, but color balance becomes unnatural and blue components are enhanced

Engineering Contradiction:

Improveshadow area gradationVSAvoidcolor balance

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent carefully manages color adjustments during shadow area brightening by applying complementary color corrections. When brightness is increased in shadow regions, the system adjusts color components to compensate for the enhancement effect, preventing unnatural color shifts and maintaining accurate color balance throughout the image.

Inventive Principle:

Principle #32Color changes

4Loss of information

If shadow area is over-brightened, then shadow area visibility is improved, but shades of entire image are impaired and somber impression is created

Engineering Contradiction:

Improveshadow area visibilityVSAvoidoverall image mood

Core Design Contradiction:

Loss of informationVSStability of the object's composition

Solution Approach 1:

The patent applies brightness enhancement selectively and moderately to shadow areas rather than uniformly across the entire image. By controlling the degree of brightening and limiting its application to specific regions, the system improves shadow visibility while avoiding excessive overall brightness that would create an unnatural or somber appearance.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7733390B2Image-processing devices, methods, and programs, and electronic cameras and the like comprising same

Publication Date: 2010.06.08 NIKON CORP

AI summary

Image-processing devices and methods are disclosed. Such a device includes an image-input unit, a fluctuation-extraction unit, a modulation-signal-generation unit, a level-compression unit, and a gradation-correction unit. The image-input unit inputs an image. The fluctuation-extraction unit extracts a local-fluctuation component from the input image and generates a local-fluctuation image containing a fluctuation component. The modulation-signal-generation unit produces a modulation signal used for modulating the input image to a local-fluctuation image. The level-compression unit level-compresses the modulation signal. The gradation-correction unit modulates the input image according to the modulation signal after level-compression, thereby producing a gradation-corrected image.