Image Pickup Apparatus Dynamic Exposure Correction

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Solution Overview

Problem

In focus stacking, moving the in-focus position during exposure causes uneven luminance in the image plane due to changes in effective aperture value, leading to noticeable boundaries and defects in the composite image when focused areas are combined.

Innovation Solution

An image pickup apparatus and method that adjust exposure times based on the relationship between in-focus position and effective aperture value to synchronize pixel reset timing and exposure, reducing differences in effective aperture values across image lines and correcting exposure times to minimize uneven luminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the in-focus position is continuously changed during exposure to reduce processing time for focus stacking, then imaging speed is improved, but uneven luminance is caused in the image plane due to changes in effective aperture value, leading to defects in the composite image

Engineering Contradiction:
Improveimaging speedVSAvoidimage quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the exposure time parameter dynamically based on the in-focus position. Specifically, the exposure time is set to be shorter when the in-focus position is closer to the imaging element and longer when it is farther away, thereby compensating for the effective aperture value changes and reducing uneven luminance in the composite image

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the exposure time is adjusted according to the current in-focus position. The control unit calculates the appropriate exposure time based on the relationship between in-focus position and effective aperture value, and dynamically adjusts the exposure time during the imaging process to maintain uniform luminance

Inventive Principle:
Principle #23Feedback

2Quantity of substance

If the in-focus position is moved during exposure to capture multiple images with different in-focus positions, then the number of images captured is increased, but the imaging time is extended

Engineering Contradiction:
Improvenumber of imagesVSAvoidimaging time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The patent employs continuous focus stacking where the in-focus position is continuously changed during exposure rather than capturing discrete images separately. This allows multiple in-focus positions to be captured in a single continuous exposure process, significantly reducing the total imaging time while still obtaining multiple images with different in-focus positions for composite processing

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4002830B1Image pick up apparatus, image pick up method, and storage medium
Publication Date: 2024.10.23 CANON KK
  • EP4002830B1 patent drawingFigure 1
  • EP4002830B1 patent drawingFigure 2
  • EP4002830B1 patent drawingFigure 3

AI summary

An image pick up apparatus includes imaging means configured to pick up an image while an in-focus position is continuously changed during pickup of the image, and correction means configured to perform correction of a difference in exposure resulting from a change in the in-focus position while the imaging means picks up one image.