Image Processing Apparatus Reducing False Contours via Weber Ratio
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Solution Overview
Problem
8-bit video signals often result in tone jumps due to quantization roughness, leading to visually recognizable false contours, which are discontinuities in gradation that make images appear uneven.
Innovation Solution
An image processing apparatus that includes a gradation conversion section to adjust gradation characteristics, a smoothing section to strengthen smoothing of signals with higher Weber ratios, and a random component addition section to add noise to signals with higher Weber ratios, excluding the neighborhood of minimum signal values, to reduce false contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-pass filter processing is applied to reduce false contours, then false contour visibility is reduced, but image resolution deteriorates due to blurring
Solution Approach 1:
The patent applies different processing strengths to different signal regions by using Weber ratio as a criterion. Signals with higher Weber ratios (where false contours are more visible) receive stronger low-pass filter processing, while signals with lower Weber ratios receive weaker processing. This local differentiation allows effective false contour suppression in critical regions while preserving image resolution in other areas.
Solution Approach 2:
The patent changes the processing parameter (filter strength) based on the Weber ratio of each signal. By dynamically adjusting the low-pass filter strength according to the Weber ratio, the system optimizes the balance between false contour reduction and resolution preservation for each specific signal region.
2Object-affected harmful factors
If stronger low-pass filter processing is applied to signals with higher Weber ratios, then false contours are reduced more effectively, but more image detail is lost
Solution Approach 1:
The patent selectively applies processing strength based on local signal characteristics (Weber ratio). Only signals with higher Weber ratios receive stronger filtering, while other signals maintain their original detail. This localized approach minimizes overall information loss while effectively addressing false contours in problematic regions.
Solution Approach 2:
The patent converts the potentially harmful effect of strong filtering (detail loss) into a benefit by selectively applying it only where necessary (high Weber ratio regions). The filtering strength is transformed from a uniform harmful operation into a targeted beneficial operation that addresses false contours without excessive detail loss.
Data Source
AI summary
An image processing apparatus includes a smoothing section configured to smooth, for an image after gradation conversion with which gradation display on a monitor becomes appropriate, a signal with a higher Weber ratio, to a signal value, of a quantization error caused by the gradation conversion with higher strength, and a random component addition section configured to add a larger random component to the signal with the higher Weber ratio excluding a neighborhood of a minimum signal value for an image after the smoothing.