Projection Apparatus Grayscale Adjustment for Colored Surfaces
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Solution Overview
Problem
Existing projection technologies face challenges in maintaining image quality when projecting onto non-exclusive-use surfaces with colors or patterns, leading to decreased dynamic range and contrast, and sometimes making color correction impossible due to low light reflectance.
Innovation Solution
A projection apparatus that acquires color information at bright and dark times on the target surface, designates projection modes based on brightness and color, and adjusts the grayscale range of projected images to reflect user intention, using a digital camera and CPU-controlled processing units to determine target gray scale values for white and black pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color correction is performed by determining target values of white and black using photographed images, then color reproduction on colored surfaces is improved, but dynamic range decreases and contrast deteriorates considerably
Solution Approach 1:
The system performs preliminary measurement of the projection surface's spectral reflectance characteristics before color correction. By acquiring spectral reflectance data in advance, the system can compensate for surface color effects during projection without needing to adjust target white/black values based on photographed images, thus preserving dynamic range and contrast while achieving accurate color reproduction.
Solution Approach 2:
The invention replaces the mechanical/optical measurement method (using a camera to photograph projected images and manually determine target values) with a spectral measurement approach. By using spectral reflectance data of the projection surface, the system substitutes direct optical measurement with spectral characterization, enabling more precise color correction without the drawbacks of image-based target value determination.
2Measurement precision
If color correction is performed using spectral reflectance of the projection surface, then color reproduction is improved, but the system complexity increases
Solution Approach 1:
The system creates a spectral reflectance profile (a digital copy of the surface's optical characteristics) and uses this copy to determine color correction parameters. Instead of directly measuring the surface during projection, the system uses pre-acquired spectral data as a reference model, simplifying the overall system architecture while maintaining high color reproduction accuracy.
Solution Approach 2:
Spectral reflectance measurement is performed as a preliminary action before actual projection. By acquiring and storing the spectral characteristics of the projection surface in advance, the system avoids the need for complex real-time spectral measurement during projection, thereby reducing operational complexity while maintaining color accuracy.
3Measurement precision
If target values of white and black are determined using photographed images, then color correction can be performed, but color correction becomes impossible when reflectance of light at a specific position is extremely low
Solution Approach 1:
The system replaces image-based target value determination with spectral reflectance measurement. By measuring the spectral characteristics of the projection surface directly (rather than relying on photographed images), the system can accurately characterize surfaces with extreme reflectance properties that would be difficult or impossible to measure using traditional image photography methods.
Solution Approach 2:
The system introduces spectral reflectance data as an intermediary that mediates between the projection surface and the color correction process. This intermediary allows the system to accurately characterize surfaces with extreme reflectance properties without directly attempting to measure them through image photography, thereby ensuring reliable color correction across all surface types.
Data Source
AI summary
A projection apparatus includes a projection mode designation unit configured to designate one of a plurality of projection modes which designate at least one of a brightness and a color of the image which is projected by the projection unit; and a projection control unit configured to determine, based on the color information of the projection target surface acquired by the projection surface information acquisition unit and the projection mode designated by the projection mode designation unit, a gray scale range of each of colors constituting the image which is projected by the projection unit, and configured to cause the projection unit to project the image.