Rolling Shutter Distortion Correction via CNN Motion Prediction

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Solution Overview

Problem

Rolling shutter cameras introduce distortions due to their row-by-row exposure mechanism, especially when the camera is in motion, making it challenging to correct these distortions using traditional geometric methods, which are often degenerate and intractable, especially under pure translational motion.

Innovation Solution

A structure-and-motion-aware convolutional neural network (CNN) is employed to learn the underlying geometry from a single rolling shutter image, predicting camera motion and depth maps to correct distortions by synthesizing training data from global shutter counterparts and using a rectification module to produce geometrically consistent and visually pleasant images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional geometric methods are used to correct rolling shutter distortions, then the correction process becomes intractable and degenerate, but using CNN-based methods introduces computational complexity

Engineering Contradiction:
Improveease of correctionVSAvoidcomputational complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent replaces traditional geometric correction methods with a CNN-based deep learning system. The CNN model learns to predict camera motion and depth directly from rolling shutter images, substituting the intractable geometric computation with a trained neural network that provides both accuracy and computational efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs preliminary action by pre-training the CNN model on synthesized rolling shutter images before deployment. The training phase prepares the network to handle various motion scenarios, so that during actual correction, the pre-trained model can quickly predict camera motion and depth without requiring complex runtime computations.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If rolling shutter cameras are used to reduce cost, then manufacturing cost decreases, but image quality deteriorates due to motion-induced distortions

Engineering Contradiction:
Improvemanufacturing costVSAvoidimage quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent converts the harmful rolling shutter distortion into a beneficial signal by training the CNN to recognize and interpret the distortion patterns. Instead of treating the row-by-row exposure artifact as merely harmful, the system learns to extract useful camera motion and depth information from the distortion itself, then uses this information to correct the image.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the need for expensive global shutter cameras with affordable rolling shutter cameras by introducing a computational correction layer. The CNN-based correction system compensates for the hardware limitation, allowing low-cost cameras to produce corrected images of comparable quality to expensive global shutter alternatives.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If CNN-based correction is applied to enable SLAM/SFM applications, then application versatility improves, but processing time increases

Engineering Contradiction:
Improveapplication versatilityVSAvoidprocessing time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces complex geometric computation pipelines required for SLAM and SFM with a streamlined CNN-based approach. The network directly predicts camera motion and depth from rolling shutter images, providing the essential inputs for SLAM/SFM algorithms more efficiently than traditional geometric methods, thus enabling these applications with reduced processing overhead.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11132586B2Rolling shutter rectification in images/videos using convolutional neural networks with applications to SFM/SLAM with rolling shutter images/videos
Publication Date: 2021.09.28 NEC CORP
  • US11132586B2 patent drawing
  • US11132586B2 patent drawing
  • US11132586B2 patent drawing

AI summary

A method for correcting rolling shutter (RS) effects is presented. The method includes generating a plurality of images from a camera, synthesizing RS images from global shutter (GS) counterparts to generate training data to train the structure-and-motion-aware convolutional neural network (CNN), and predicting an RS camera motion and an RS depth map from a single RS image by employing a structure-and-motion-aware CNN to remove RS distortions from the single RS image.