Content-Aware Image Rotation Using Mesh Warping
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Solution Overview
Problem
Conventional image editing techniques for correcting tilted digital images often result in content loss due to cropping or the addition of non-original content, as they struggle to rotate images while preserving the entire original content without altering its boundaries.
Innovation Solution
A content-aware image rotation correction system that uses a mesh-based approach with an energy function to rotate horizontal and vertical lines by a fixed angle, while allowing oblique lines to be rotated by different angles, ensuring that the original image content is preserved without cropping or filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional image editing techniques rotate the image about the tilt angle and crop the resulting tilted image to a desired size, then the image tilt is corrected, but content is removed (up to 20% of original content)
Solution Approach 1:
The patent segments the image into a mesh of quadrilaterals that can be independently transformed. This allows different regions of the image to be rotated by different amounts, enabling precise correction of tilt while preserving all original content without cropping.
Solution Approach 2:
The patent applies local quality by allowing different mesh elements to have different rotation angles and transformation properties. Horizontal and vertical lines are constrained to rotate by the tilt angle, while other lines can rotate by different amounts to preserve content and achieve aesthetically pleasing results.
2Loss of substance
If methods add content instead of cropping to preserve original content, then content loss is avoided, but non-original content is introduced into the image
Solution Approach 1:
The patent employs dynamic mesh transformation where the mesh structure adapts to the image content and rotation requirements. The mesh elements are dynamically adjusted to preserve original content while achieving the desired rotation correction, avoiding the need to add external content.
3Manufacturing precision
If seams are created within the image content and content is added or removed at those seams, then rotation correction is achieved, but the corrected image has altered content
Solution Approach 1:
The patent transitions from 2D image space to a 3D mesh space for transformation, then maps back to 2D. This dimensional change allows complex rotations and content preservation simultaneously by operating in the additional degree of freedom provided by the mesh structure.
4Device complexity
If all lines are rotated by the same fixed angle, then rotation correction is simple, but oblique lines may not achieve aesthetically pleasing results and content may be lost
Solution Approach 1:
The patent applies local quality by allowing different mesh elements to have different rotation angles and transformation properties. Horizontal and vertical lines are constrained to rotate by the tilt angle, while other lines can rotate by different amounts to preserve content and achieve aesthetically pleasing results.
Data Source
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AI summary
According to implementations of this disclosure, image content is rotated in a content-aware fashion. In one implementation, a mesh is formed over an image and image lines in the image content are identified. The image is warped using an energy function that rotates a subset of the lines a predetermined rotation angle, while rotating other lines by an angle other than the predetermined rotation angle. In one example, lines that are intended to be horizontal or vertical after correcting are rotated by a rotation angle that will make them horizontal or vertical, whereas oblique lines are rotated by an angle other than the rotation angle.