Projection System Gamma Correction for Luminance Unevenness
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Solution Overview
Problem
Existing techniques for reducing luminance and color unevenness in projected images require high-performance imaging devices and high-luminance projectors, making them unsuitable for applications with narrow dynamic range and low-luminance projections.
Innovation Solution
A projection system comprising a projection unit, imaging unit, gamma characteristic obtaining unit, pixel mapping unit, response characteristic obtaining unit, coefficient setting unit, target image obtaining unit, and correction unit, which processes input images to reduce saturated pixels and correct for gamma characteristics, allowing for effective image projection without high-luminance projectors or high-performance imaging devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-performance imaging device is used to capture the projected image, then the measurement precision of luminance values is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces expensive high-performance imaging devices with a standard smartphone camera, which is a readily available, low-cost device. The smartphone's imaging sensor captures the projected image with sufficient precision for the correction process, eliminating the need for specialized expensive equipment while achieving the same correction results.
Solution Approach 2:
The patent uses the smartphone to capture a copy of the projected image, which is then processed to create correction data. This captured image copy is sufficient for calculating the light distribution map and response function, avoiding the need for the original high-performance imaging device while maintaining measurement accuracy.
2Illumination intensity
If a high-luminance projector apparatus is used to project the image, then the dynamic range of the projected image is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent changes the approach from increasing projector luminance to adjusting image processing parameters. By modifying the correction algorithm to account for low-light conditions and using gamma correction adapted to the smartphone's display characteristics, the system achieves effective correction with low-luminance projectors, eliminating the need for high-power projection equipment.
Solution Approach 2:
The patent enables the use of inexpensive, low-power projectors by compensating for their limited luminance through software-based correction methods. The system adapts the correction process to work effectively with low-luminance projections captured by standard smartphone cameras, making high-performance equipment unnecessary.
3Measurement precision
If the correction process uses a wide dynamic range assumption, then the correction accuracy is improved, but the adaptability to narrow dynamic range projections deteriorates
Solution Approach 1:
The patent implements dynamic adaptation of the correction process based on the actual luminance characteristics of the projected image. The system automatically adjusts the correction algorithm parameters according to whether the projection has wide or narrow dynamic range, enabling accurate correction for both low-luminance and high-luminance projections without requiring separate correction processes.
Solution Approach 2:
The patent changes the correction parameters based on the measured luminance characteristics of the specific projection being corrected. By calculating the light distribution map and response function from actual captured images rather than assuming fixed parameters, the system adapts to both wide and narrow dynamic range projections, achieving accurate correction across different projection conditions.
Data Source
AI summary
Even when a high-performance imaging apparatus is not used, luminance unevenness and color unevenness of an image (video) projected on a projection plane by the projection type projector apparatus are appropriately reduced. Using a coefficient Br (0≤Br≤1) set by a coefficient setting unit, the projection system obtains, based on the gamma characteristic of the entire system of the projection system, a target image for reducing the number of pixels saturated when the image is projected. Then, the projection system performs correction processing using the obtained target image based on the gamma characteristic of the entire system of the projection system and a white value. This reduces the number of saturated pixels of the projected image in the projection system. Furthermore, even in a case or similar cases when a captured image obtained by capturing a projected image has a bad S/N ratio, image projection processing that does not cause a user discomfort in viewing the projected image (or captured image) is achieved.