Projection Device Pixel Scale Correction for Trapezoidal Distortion
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Solution Overview
Problem
Conventional projection devices face issues with trapezoidal distortion when the optical axis of the projection lens is inclined relative to the projection face, leading to inefficient use of display device pixels and reduced brightness, especially with high-resolution video content that exceeds the display device's resolution.
Innovation Solution
A projection device with a correction unit that adjusts the scale of image data based on the position of pixel lines and the inclination of the projection direction, and an image cutting-out unit that optimizes the projection area to effectively utilize the display device's pixels by supplementing information in the peripheral areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If trapezoidal distortion correction is performed by converting the image into an opposite trapezoidal shape, then the projection image becomes rectangular without distortion, but the pixel area of the display device is not effectively used and brightness decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the scale of image data in the vertical direction based on the projection angle. When the optical axis is inclined, the correction unit calculates the appropriate scale factor and applies it to the image data, transforming the rectangular image into a trapezoidal shape that matches the projection surface, thereby eliminating distortion while optimizing pixel utilization
Solution Approach 2:
Instead of converting the image into an opposite trapezoidal shape and leaving peripheral areas unused, this patent inverts the approach by scaling the image data to create a trapezoidal image that fully utilizes the display device's pixel area. The image is transformed to match the projection geometry, ensuring all pixels contribute to the effective projection area
2Adaptability or versatility
If the optical axis of the projection lens is inclined with respect to the projection face, then projection flexibility is improved, but trapezoidal distortion occurs
Solution Approach 1:
The patent detects the projection angle and dynamically changes the scaling parameter of the image data in the vertical direction. Based on the detected angle, the correction unit applies an appropriate scale factor to transform the rectangular image into a trapezoidal shape that compensates for the inclination, thereby maintaining image rectangularity on the projection surface while allowing optical axis inclination for flexibility
3Manufacturing precision
If high-resolution video content is input that exceeds the display device resolution, then image quality is improved, but the image cannot be fully displayed without scaling or cropping
Solution Approach 1:
The patent applies scale correction to the image data in the vertical direction based on the projection angle. By dynamically adjusting the vertical scale parameter, the system can display high-resolution content on the display device while accounting for the trapezoidal distortion caused by inclined projection, thereby utilizing the full display area without losing image quality
Data Source
AI summary
A projection device includes a projection unit including a display element in which pixel lines each formed by pixels arranged in a first direction are arranged in a second direction and an optical system that projects light emitted from the display element and projecting an image based on input image data, a first correction unit for correcting a scale of each line data of the image data that corresponds to each of the pixel lines, a second correction unit for correcting a second-direction scale of each pixel data of the image data after the correction performed by the first correction unit, and an image cutting-out unit for cutting out image data of an area, which is projected from the projection unit, of the image data after the correction performed by the second correction unit and input the image data of the area to the projection unit.