Focus Estimating Device Block Selection for Autofocus Accuracy

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Solution Overview

Problem

Existing autofocus devices cannot accurately determine the direction of lens position deviation from the focusing position, leading to low focus state determination accuracy.

Innovation Solution

A focus estimating device that sets an area for focus determination, divides it into blocks, selects blocks based on edge components, and performs focus determination using color component gradients to accurately determine focusing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If focus determination is performed using chromatic aberration of light, then autofocus function is achieved, but determination accuracy of focus state is low

Engineering Contradiction:

Improveautofocus functionVSAvoidfocus state determination accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The image is divided into multiple blocks, and focus determination is performed for each block separately. This segmentation allows the system to identify blocks with sufficient edge information for accurate focus measurement while excluding blocks that would degrade precision, thereby resolving the contradiction between achieving autofocus functionality and maintaining high focus state determination accuracy.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If focus determination is performed for the entire image area, then comprehensive focus assessment is achieved, but determination accuracy decreases due to inclusion of unsuitable blocks

Engineering Contradiction:

Improvefocus determination areaVSAvoidfocus determination accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

Different blocks within the image area are evaluated based on their local characteristics, specifically the presence of edges in color components. Blocks with sufficient edge information are selected for focus determination, while blocks lacking appropriate features are excluded. This local quality assessment ensures that focus determination is performed only in regions suitable for accurate measurement, resolving the contradiction between comprehensive area coverage and determination accuracy.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If all blocks are used for focus determination, then processing coverage is maximized, but calculation efficiency decreases

Engineering Contradiction:

Improveblock coverageVSAvoidfocus determination efficiency

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

Blocks that do not meet the selection criteria (insufficient edge information in color components) are extracted and excluded from focus determination processing. Only the necessary blocks with appropriate characteristics are retained for calculation. This extraction of unsuitable blocks from the processing pipeline maximizes computational efficiency while maintaining adequate coverage of the image area for accurate focus determination.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9648227B2Focus estimating device, imaging device, and storage medium storing image processing program

Publication Date: 2017.05.09 NIKON CORP

AI summary

A focus estimating device has an area setting unit which sets an area in which focusing of an image is determined and divides the area into a plurality of blocks, a block selecting unit which selects a block to be used for focus determination, a block focus determination unit which performs focus determination for each block from an edge in each color component of the block selected by the block selecting unit, and a focus determination unit which determines focusing of the area based on the focus determination.