Rolling Shutter Distortion Correction in CMOS Image Sensors
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Solution Overview
Problem
Existing image processing techniques for correcting rolling shutter distortion in CMOS image pickup devices often result in incorrect setting of the reference line, leading to object position shifts and new blur issues during image stabilization.
Innovation Solution
An image processing apparatus that includes a shake detection unit, a distortion correction amount calculation unit, and a correction unit, which calculates and applies distortion correction amounts based on the position of the optical correction unit at the center between the start and end of charge accumulation, ensuring accurate reference line setting and minimizing shake-induced image blur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rolling shutter distortion correction is performed using conventional methods, then distortion correction is achieved, but object position shifts and new blur occurs due to incorrect reference line setting
Solution Approach 1:
The patent uses feedback from the image stabilization amount calculation unit to determine the reference line position. The reference line is set based on the actual image stabilization amounts detected during charge accumulation, creating a closed-loop system that adapts to real shake conditions rather than using fixed conventional reference lines
Solution Approach 2:
The patent calculates and determines the reference line position before performing distortion correction. By pre-calculating the reference line based on anticipated or detected shake patterns during the charge accumulation period, the system prepares the correct reference framework in advance, preventing position shifts during the actual correction process
2Ease of manufacture
If the reference line is set at the uppermost line of the captured image, then distortion correction can be applied, but object position shifts occur in the output image
Solution Approach 1:
The patent dynamically changes the reference line parameter from a fixed position (uppermost line) to a variable position determined by actual shake detection. The reference line position is adjusted based on the calculated image stabilization amounts, transforming it from a static conventional parameter to a dynamic adaptive parameter that maintains object position accuracy
3Productivity
If discrete shake amounts are acquired to synchronize with read timings, then rolling shutter distortion can be corrected, but the reference line position becomes unclear leading to correction errors
Solution Approach 1:
The patent introduces an intermediary calculation step where the reference line position is derived from the image stabilization amount calculation. This intermediary process bridges the gap between discrete shake detection and continuous distortion correction, providing the missing reference line position information that connects the shake data to the correction application
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
The solution effectively corrects rolling shutter distortion while maintaining the object's original position, preventing new blur occurrences and ensuring high-quality video capture with reduced shake influence.
Implementation Method 1
an image pickup device configured to change, between lines, a timing to receive light of an object image formed by an imaging optical system and accumulate charges
Implementation Method 2
a shift lens configured to optically correct an image blur caused by a shake based on an output of the shake detection unit
Data Source
AI summary
An image capturing apparatus includes an image capturing unit configured to change, between lines, a timing to receive light of an object image formed by an imaging optical system and accumulate charges, a storage unit configured to store a captured image, a shake detection unit configured to detect a shake, an image stabilization unit configured to optically correct an image blur caused by the shake, a distortion correction amount calculation unit configured to calculate, based on the output of the shake detection unit, a distortion correction amount used to correct a distortion caused in the image by the shake during charge accumulation of the image capturing unit, and a correction unit configured to correct the image stored in the storage unit based on the distortion correction amount.