Image Brightness Adjustment via Surface Normal Map
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Solution Overview
Problem
Existing image adjustment technologies fail to effectively adjust the brightness of images by accurately simulating lighting conditions, particularly for objects like human faces, leading to unnatural or inconsistent results.
Innovation Solution
A method that generates a surface normal map by interpolating normal vectors at feature points of an object model, applies shadow information based on a virtual light source, and adjusts the tone of the image using a brightness histogram, allowing for real-time preview and editing of images to enhance lighting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex 3D models and calculations are used to simulate lighting conditions, then the accuracy of brightness adjustment is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The patent uses a 2D surface normal map as a simplified copy representation of 3D surface information, which captures the essential lighting interaction data without requiring full 3D model complexity. This allows accurate brightness simulation using lightweight 2D data structures that can be efficiently processed on mobile devices.
Solution Approach 2:
The patent extracts only the critical surface normal information from complex 3D models and represents it in a simplified 2D map format. By taking out just the essential geometric data needed for lighting simulation (surface orientations) and discarding unnecessary 3D model complexity, the system achieves accurate brightness adjustment with reduced computational overhead.
2Productivity
If real-time processing is implemented for image brightness adjustment, then the user interaction responsiveness is improved, but the computational load and processing time increase
Solution Approach 1:
The patent pre-calculates and stores surface normal maps and lighting information in a compressed 2D format before image processing. This preliminary preparation of geometric data allows the system to perform real-time brightness adjustments by simply applying pre-computed lighting calculations to the image pixels, significantly reducing processing time during actual image editing operations.
Solution Approach 2:
The patent replaces computationally intensive 3D rendering mechanics with simplified 2D image processing operations. By substituting complex 3D model transformations and ray tracing with straightforward 2D pixel operations using pre-computed surface normals, the system achieves real-time performance on mobile devices with limited processing power.
3Device complexity
If simple image processing methods are used, then the device complexity is reduced, but the naturalness and realism of lighting effects deteriorate
Solution Approach 1:
The patent changes the representation parameters from full 3D model data to 2D surface normal maps with encoded lighting information. This parameter transformation maintains the essential geometric and lighting data needed for realistic illumination effects while reducing data complexity to levels suitable for mobile device processing, achieving both simplicity and realism.
Data Source
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AI summary
A method of adjusting a brightness of an image includes matching an object model to an object based on one or more feature points of the object extracted from an input image including the object; mapping a surface normal map in a two-dimensional (2D) image form to the input image based on the matched object model; and generating shadow information for the input image based on the mapped surface normal map and a virtual light source.