Digital Camera Extended Focus via Dynamic Aperture and Image Merging
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Solution Overview
Problem
Digital cameras with fixed focus lenses face challenges in capturing images of subjects closer than the near focus position, as they lack adjustable focus settings, making it difficult for amateur photographers to achieve acceptable focus and depth of field.
Innovation Solution
A digital camera system that varies the F/# of its optical system between minimum and maximum settings to automatically adjust for focus, capturing evaluation images to determine optimal F/# settings, ensuring subjects are acceptably focused and extending the depth of field adaptively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed focus lens is used to reduce costs and simplify the system, then device complexity is reduced, but the ability to capture subjects at varying distances (adaptability) deteriorates
Solution Approach 1:
The patent changes the F/# parameter of the optical system dynamically. By varying the aperture size (F/# setting), the depth of field is adjusted to include subjects at different distances. The system captures images at multiple F/# settings and combines them, allowing a fixed focus lens to achieve extended depth of field coverage without requiring focus adjustment mechanisms.
2Manufacturing precision
If the F/# is increased to extend depth of field for closer subjects, then the depth of field increases, but the image noise increases due to reduced light intake
Solution Approach 1:
The patent merges multiple images captured at different F/# settings into a composite image. By combining images taken at various aperture settings (including both smaller and larger F/# values), the system achieves extended depth of field while maintaining image quality. The merging process allows selection of the sharpest regions from each image, reducing noise while preserving focus precision.
3Manufacturing precision
If multiple images are captured at different F/# settings to extend depth of field, then the depth of field coverage is improved, but the time required to capture the image increases
Solution Approach 1:
The patent employs periodic action by capturing a sequence of images at different F/# settings in rapid succession. The system systematically varies the aperture setting between captures, obtaining multiple images with different depth of field characteristics. This periodic variation in F/# settings allows the system to gather necessary data for extended depth of field while maintaining efficient capture timing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables focused images of subjects closer than the near focus position and adaptively controls depth of field, providing a tradeoff between subject focus, image noise, and motion blur.
Implementation Method 1
Digital cameras use a lens to focus a scene onto an image sensor
Data Source
AI summary
A digital camera system providing an extended focus range, comprising: a program memory storing instructions to implement a method for capturing a focused digital image. The method includes: setting an optical system F/# to a first F/#; capturing an evaluation image of the scene; analyzing the evaluation image to determine whether a subject is acceptably focused; if the subject is acceptably focused setting a capture F/# to be equal to the first F/#, otherwise the optical system F/# is iteratively increased until the subject is determined to be acceptably focused, or until a maximum F/# is reached; determining a capture F/# responsive to the F/# where the subject is acceptably focused; setting the optical system to use the capture F/#; capturing an archival image of the scene using the image sensor; and storing the captured archival image in a storage memory.