Adaptive Image Binarization via Histogram Analysis

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Solution Overview

Problem

Existing image binarization methods, such as the Otsu method, are inefficient for processing images with complex distributions, as they rely on a single global threshold and fail to effectively handle images with multiple classes or varying pixel values, leading to suboptimal binarization results.

Innovation Solution

An approach that selects between global and local thresholding methods based on histogram analysis, using characteristics like spike count, kurtosis, and cluster number to determine appropriate thresholding strategies, allowing for multiple threshold values to be applied across different image sub-blocks or the entire image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single global threshold is used for binarization, then the processing is simple and fast, but the binarization accuracy deteriorates for images with complex distributions

Engineering Contradiction:
Improveprocessing speedVSAvoidbinarization accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent divides the image into multiple sub-blocks and applies different thresholding methods to each sub-block based on its local histogram characteristics. This segmentation allows the system to maintain simple global processing while achieving accurate local binarization for complex images with multiple distributions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically selects between global and local thresholding methods based on histogram analysis of the image or sub-block. The selection is not fixed but adapts to the actual image characteristics, choosing the most appropriate method (global or local) for each specific case to balance speed and accuracy.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the Otsu method is used for threshold selection, then bi-modal images are processed efficiently, but other types of images with complex distributions cannot be handled effectively

Engineering Contradiction:
Improveimage type coverageVSAvoidthreshold determination complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal threshold determination system that can handle multiple image types (bi-modal, multi-modal, complex distributions) by supporting both global and local thresholding methods. The system automatically selects the appropriate method based on histogram characteristics, making it versatile across different image types without requiring separate specialized algorithms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the parameter of threshold determination from a single fixed method (Otsu) to a selectable family of methods (global and local variants). By analyzing histogram parameters like modality and distribution complexity, the system adjusts which thresholding approach to use, effectively changing the determination parameter to match the image characteristics.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If local thresholding is applied to all image sub-blocks, then binarization accuracy for complex images is improved, but processing complexity and time increase

Engineering Contradiction:
Improvebinarization accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local thresholding only to sub-blocks that require it based on their specific histogram characteristics, rather than uniformly to all sub-blocks. This local quality approach ensures high accuracy for complex regions while maintaining simpler processing for regions that don't require local analysis, reducing overall processing complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent performs partial local thresholding by selecting only certain sub-blocks for local processing based on histogram analysis, rather than applying local thresholding to the entire image. This partial action approach achieves necessary accuracy improvements while avoiding the excessive processing complexity that would result from universal local thresholding.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS8351699B2Methods and apparatus for auto image binarization
Publication Date: 2013.01.08 ACCUSOFT CORP
  • US8351699B2 patent drawing
  • US8351699B2 patent drawing
  • US8351699B2 patent drawing

AI summary

A threshold determination method is selected from among a plurality of alternative global thresholding determination methods and, optionally, a local thresholding determination method based on characteristics of a histogram of grayscales values representing an image. When it is determined to use a global thresholding method, a single global binarization threshold value is determined using the selected global thresholding method. Various alternative global binarization threshold values include a predetermined constant, an average value of the two grayscale values, an Otsu method based threshold value, a Newton method based threshold value, and an Otsu method based threshold value based on a truncated version of the histogram. When it is determined to use local thresholding, a plurality of local binarization threshold values are determined corresponding to different non-overlapping blocks of the image. The determined binarization threshold(s) are applied to the gray scale pixel values to obtain a set of binary pixel values.