Projection Pixel Shifting Beyond Half-Pixel to Reduce Artifacts
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Solution Overview
Problem
Wobulation techniques in projection systems create artifacts such as increased pixel size, distorted pixel shape, and movement of pixel center-of-mass due to non-instantaneous transitions, affecting image resolution and contrast.
Innovation Solution
Implementing mitigation techniques such as controlling the DMD to an 'off' position during transitions and expanding the wobulation path beyond half a pixel distance to reduce artifacts, along with calibrating the wobulation path to minimize image distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel-shifting techniques are used to achieve higher resolution than the DMD, then image resolution is improved, but image quality degrades due to artifacts such as increased pixel size, distorted pixel shape, and movement of pixel center-of-mass
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction data that compensates for wobulation artifacts before the actual projection occurs. The system determines the optimal shift amounts and correction factors in advance, allowing the projection system to apply these pre-computed corrections during real-time operation, thereby maintaining high resolution while eliminating image quality degradation
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the shift amounts and timing parameters of the wobulation process. By modifying these parameters based on pre-calculated correction data, the system optimizes the pixel-shifting process to achieve higher resolution without the typical artifacts of increased pixel size, distorted shapes, or center-of-mass movement
2Measurement precision
If the system shifts pixels by fractional amounts in a set pattern to create the appearance of additional pixels, then displayed resolution is increased, but transition time between positions increases causing motion blur
Solution Approach 1:
The patent applies periodic action by implementing a systematic pattern of pixel shifts that occur at regular intervals and follow a predetermined sequence. The pixel-shifting operates in periodic cycles where the modulator shifts to different positions in a consistent pattern, allowing the system to maintain high displayed resolution while managing transition times through rhythmic, predictable operation
Solution Approach 2:
The system uses preliminary action by pre-calculating the optimal shift pattern and timing before the projection sequence begins. This advance planning allows the system to execute rapid, precise pixel shifts with minimized transition times, as the entire shift sequence is predetermined and optimized in advance
3Measurement precision
If the modulator is shifted rapidly between positions to create high resolution, then image resolution is improved, but pixel center-of-mass moves causing image distortion
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting the shift amounts and timing parameters of the wobulation process. By modifying these parameters based on pre-calculated correction data, the system optimizes the pixel-shifting process to achieve higher resolution without the typical artifacts of increased pixel size, distorted shapes, or center-of-mass movement
Solution Approach 2:
The system applies feedback by using pre-calculated correction data that accounts for and compensates center-of-mass movement. This correction data acts as a feedback mechanism that adjusts the pixel-shifting parameters to counteract the natural tendency of the center-of-mass to move during rapid transitions, thereby maintaining proper pixel shape and position
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
Enhances image resolution, contrast ratio, and dynamic range by reducing wobulation artifacts, resulting in high-quality image projection.
Implementation Method 1
A DMD may utilize a two-dimensional array of mirrors which can be controlled to create an image
Implementation Method 2
the system may be controlled to effectively shift the modulator, or a device situated optically after the modulator, by fractional pixels in a set pattern to create the appearance of displaying additional pixels
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A projection system for pixel shifting comprising a light source configured to emit light and a spatial light modulator configured to receive the light and generate a modulated light. The spatial light modulator includes a plurality of micromirrors. The projection system includes a wobulation device configured to shift the modulated light by fractional pixels. The projection system includes a controller configured to, for each of a plurality of subperiods, control the light source to emit the light onto the spatial light modulator, and between each of the plurality of subperiods and with the wobulation device, shift the modulated light by a partial pixel distance greater than a half-pixel distance.