Deep Learning Autofocus for Face Detection in Complex Lighting

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Solution Overview

Problem

Conventional camera autofocus systems face challenges in accurately focusing on a subject's face, especially in conditions like backlighting, small subject sizes, side-view faces, and moving subjects, leading to inefficiencies and the need for manual focus adjustments.

Innovation Solution

A deep-learning-based autofocus system utilizing a fully convolutional network algorithm processes image content to separate body and head areas, allowing for automatic or user-selected focus on a subject's face or head by computing distances and applying heat maps and masks to distinguish and isolate head regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional face detection methods are used for autofocus, then the system is simple and fast, but it fails in complex scenarios such as backlighting, small subjects, side-view faces, and moving subjects

Engineering Contradiction:
Improveautofocus accuracyVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary deep learning model that acts as a mediator between the image input and the autofocus mechanism. This model processes the image to generate segmented maps identifying body and head regions, enabling reliable autofocus in complex scenarios without directly modifying the core autofocus hardware

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies segmentation by dividing the image into distinct regions (body areas and head areas) using a deep learning model. This segmentation allows the system to reliably identify and focus on the head region even when conventional face detection fails due to lighting, size, or orientation issues

Inventive Principle:
Principle #1Segmentation

2Reliability

If manual focus selection is used, then the photographer can select the desired autofocus point, but it requires waiting and reduces shooting speed

Engineering Contradiction:
Improvefocus precisionVSAvoidshooting speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements self-service by enabling the camera system to automatically select and focus on the subject's head without requiring manual intervention. The deep learning model autonomously identifies the head region and guides the autofocus mechanism, eliminating the need for photographer waiting and manual adjustments while maintaining precise focus

Inventive Principle:
Principle #25Self-service

3Measurement precision

If the subject is small in the image, then conventional face detection may fail, but increasing image processing complexity may slow down the system

Engineering Contradiction:
Improveface detection accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by using the deep learning model to pre-process and segment the image into body and head regions before the autofocus operation. This preliminary segmentation identifies small subjects early, allowing the system to focus on the correct region without time-consuming trial-and-error adjustments during the actual autofocus process

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS10666858B2Deep-learning-based system to assist camera autofocus
Publication Date: 2020.05.26 SONY GROUP CORP
  • US10666858B2 patent drawing
  • US10666858B2 patent drawing
  • US10666858B2 patent drawing

AI summary

To overcome several issues of autofocusing, a deep-learning-based autofocus system utilizes a subject's body to autofocus on the subject's face. The subject, including the subject's body and face/head, are determined utilizing image processing methods, and based on the detection, the subject's face/head is automatically focused on.