Projection Image Compensation Using Adaptive Brightness and Frequency Control
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Solution Overview
Problem
The reduction in the number of lenses in projection optical systems for projectors leads to degradation in resolution and imaging performance, such as distortion aberration and chromatic aberration, which existing methods struggle to fully compensate without requiring special SLM structures and resulting in image distortion.
Innovation Solution
An image processing method and apparatus that includes a spatial light modulator and a projection optical system, where an image processing device performs compensations by highlighting high-frequency ranges and adjusting brightness levels within the dynamic range of the SLM, using nonlinear adaptive filters to generate and update image information, ensuring accurate projection of images despite lens degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of lenses in the projection optical system is reduced for downsizing and weight reduction, then the device complexity and weight are decreased, but the resolution and imaging performance (such as distortion aberration and chromatic aberration) are degraded
Solution Approach 1:
The patent replaces the mechanical/optical approach of using multiple lenses for aberration correction with an electronic/image processing approach. The image processing device performs digital signal processing to compensate for distortion aberration and chromatic aberration, substituting the need for complex optical systems with computational methods. This allows the projection optical system to use fewer lenses while maintaining imaging quality through software-based correction.
2Manufacturing precision
If the shape or structure of the SLM is modified to compensate for projection optical system aberrations, then the aberration compensation is improved, but the device complexity increases and sufficient compensation for resolution degradation is difficult to achieve
Solution Approach 1:
Instead of modifying the SLM structure to adapt to the projection optical system's aberrations, the patent inverts the approach by modifying the image signal to pre-compensate for the known aberrations. The image processing device applies inverse transformations to the image data that counteract the expected distortion and chromatic aberration from the projection optical system, allowing the use of a standard SLM without structural modifications.
3Ease of operation
If conventional image processing methods are used to compensate for lens degradation, then the processing simplicity is maintained, but the image distortion is not sufficiently corrected
Solution Approach 1:
The patent applies specific parameter changes in the image processing to compensate for lens degradation. The image processing device adjusts parameters such as spatial frequency components, brightness distribution, and color balance based on the characteristics of the projection optical system. By changing these parameters in the digital domain, the system achieves sufficient correction of image distortion while maintaining relatively simple processing operations.
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
This approach effectively compensates for lens degradation, maintaining image quality by adjusting brightness and frequency components, resulting in a projection image that closely resembles the source image without distortion, while optimizing the performance of both the projection optical system and the SLM.
Implementation Method 1
a spatial light modulator (SLM) such as a liquid crystal light modulator that modulates a light beam emitted from the lighting optical system based on image information
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
When it is estimated that first average brightness of image information of a projection image is under second average brightness of image information of a source image having a single spatial frequency on which a normal compensation is performed, an area having brightness above the second average brightness in the image information of the projection image is increased, and when it is estimated that the first average brightness is above the second average brightness, an area having brightness under the second average brightness in the image information of the projection image is increased.