F-Number Adaptive Image Processing for Small-Aperture Soft Focus

Solution Overview

Problem

Existing imaging optical systems struggle to maintain a soft focus effect when using a small aperture, as the influence of spherical aberration diminishes with increased F-number, reducing the image effect.

Innovation Solution

An image processing apparatus that utilizes a deteriorating filter based on the point spread function (PSF) or optical transfer function (OTF) of the imaging optical system to enhance the soft focus effect even at small apertures by adjusting the deterioration amount in the image processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a small aperture (large F-number) is used in the imaging optical system, then depth of field and sharpness are improved, but the soft focus effect is reduced due to diminished spherical aberration influence

Engineering Contradiction:

Improveimage sharpnessVSAvoidsoft focus effect

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent creates a virtual copy of the aberration effect through computational processing. By generating a point spread function (PSF) that simulates spherical aberration characteristics and applying it as a filter to the captured image, the system reproduces the soft focus effect that would naturally occur with a large aperture, thereby decoupling the soft focus effect from the actual aperture setting.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/optical mechanism of generating spherical aberration through physical aperture control with a computational mechanism. Instead of relying on the optical system's physical aberration properties, the invention uses digital signal processing to synthesize and apply an artificial point spread function, substituting optical physics with computational algorithms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a large aperture (small F-number) is used to enhance the soft focus effect through spherical aberration, then image effect is improved, but image sharpness and resolution are reduced

Engineering Contradiction:

Improvesoft focus effectVSAvoidimage sharpness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent creates a virtual copy of the aberration effect through computational processing. By generating a point spread function (PSF) that simulates spherical aberration characteristics and applying it as a filter to the captured image, the system reproduces the soft focus effect that would naturally occur with a large aperture, thereby decoupling the soft focus effect from the actual aperture setting.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/optical mechanism of generating spherical aberration through physical aperture control with a computational mechanism. Instead of relying on the optical system's physical aberration properties, the invention uses digital signal processing to synthesize and apply an artificial point spread function, substituting optical physics with computational algorithms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If spherical aberration is intentionally generated to provide soft focus effect, then image effect is improved, but the effect is lost when using small aperture

Engineering Contradiction:

Improvesoft focus effectVSAvoidconsistency of image effect

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces dynamic adaptability by making the point spread function adjustable based on imaging conditions. The system can modify the PSF parameters (such as sigma values in Gaussian functions) according to the F-number and other shooting conditions, allowing the soft focus effect to be maintained or enhanced across different aperture settings rather than being fixed to specific optical conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent creates a virtual copy of the aberration effect through computational processing. By generating a point spread function (PSF) that simulates spherical aberration characteristics and applying it as a filter to the captured image, the system reproduces the soft focus effect that would naturally occur with a large aperture, thereby decoupling the soft focus effect from the actual aperture setting.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS12430721B2Image processing apparatus, image pickup apparatus, image processing method, and storage medium

Publication Date: 2025.09.30 CANON KK

AI summary

An image processing apparatus includes at least one memory configured to store instructions, and at least one processor configured to execute the instructions to acquire a captured image obtained using an optical system, and information on an imaging condition corresponding to the captured image, and perform deteriorating processing for the captured image based on an F-number of the optical system, the F-number being included in the information on the imaging condition. A first deterioration amount in the deteriorating processing in a case where the F-number is a first F-number is smaller than a second deterioration amount in the deteriorating processing in a case where the F-number is a second F-number larger than the first F-number.