Projector Black Level Blending for Tint and Brightness Uniformity
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Solution Overview
Problem
Current methods for black level blending in projectors fail to account for varying intensities and tints between different projectors or within a single projector, leading to distracting brightness and color differences, especially in low light conditions, and are hindered by difficulties in accurate measurement and manual input processes.
Innovation Solution
An automated method using a computing device to project color channel images at varying video levels, acquire digital images with sensors, determine respective functions for brightness, and control projector points to achieve uniform black levels through linear functions, accounting for tint and intensity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual input methods are used to adjust relative brightness of projectors, then some blending can be achieved, but the process is slow, requires guessing, and does not properly account for tint variations or brightness variations across the image
Solution Approach 1:
The patent replaces manual mechanical adjustment with an automated optical measurement system. A camera captures images of projected test patterns, and software automatically analyzes the black level characteristics across different regions and color channels, eliminating the need for manual brightness input and guessing.
Solution Approach 2:
The patent introduces a camera as an intermediary device to objectively measure black levels. Instead of relying on human perception and manual input, the camera captures quantitative data about the projected image's black level, including intensity and tint variations across different regions.
2Extent of automation
If automated binary search methods are used to estimate relative black levels, then some automation is achieved, but the process is processing-intensive and does not properly account for camera sensitivities, projector variations, or tint differences
Solution Approach 1:
The patent performs preliminary characterization of each projector and camera combination before blending. Test patterns are projected and captured to establish individual device profiles, including their specific black level characteristics, color channel responses, and spatial uniformity. This preliminary data is stored and used to guide the blending process.
Solution Approach 2:
The patent applies different adjustment parameters to different regions of the projected image and different color channels. Instead of a single global brightness adjustment, the system calculates region-specific and channel-specific correction factors based on the captured images, accounting for spatial and chromatic variations in black levels.
3Device complexity
If non-specialized cameras are used to measure black levels, then equipment complexity is reduced, but measurement accuracy is compromised because black light is too dim and measurements are dominated by noise
Solution Approach 1:
The system performs preliminary exposure optimization by capturing test images at multiple exposure values and selecting the optimal exposure settings for black level measurement. This preliminary calibration allows standard cameras to achieve sufficient sensitivity for measuring low-level black light without requiring specialized high-sensitivity sensors.
Solution Approach 2:
The patent uses multiple exposure values and captures multiple images to overcome the limitations of standard camera sensors. By taking measurements at different exposure levels and combining them, the system ensures that even dim black light produces measurable signals above the noise floor.
4Productivity
If current black level blending methods are used, then some overlap region blending is achieved, but they fail to account for tinted black levels and differing brightness intensities, leading to distracting brightness and color differences
Solution Approach 1:
The patent applies different adjustment parameters to different regions of the projected image and different color channels. Instead of a single global brightness adjustment, the system calculates region-specific and channel-specific correction factors based on the captured images, accounting for spatial and chromatic variations in black levels.
Solution Approach 2:
The patent independently adjusts multiple parameters including brightness intensity, tint (color balance), and regional variations. The system modifies these parameters based on quantitative analysis of captured images to achieve uniform black levels across overlap regions while maintaining overall image quality.
Data Source
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AI summary
A device controls at least two projectors to project color channel images at multiple video levels, with partial overlap in an overlap region. Using at least one sensor, the device acquires digital images of the projected color channels and determines functions of projected brightness relative to video level for each projector's points. The device selects brightness levels for points outside the overlap region to blend brightness inside and outside the overlap region when projecting black images. The device then determines video levels for each color channel using the functions and controls the projectors accordingly.