Rolling-Shutter Imaging for Subsurface Scattering Extraction
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Solution Overview
Problem
Existing imaging techniques struggle to effectively capture information about the subsurface structure of an object due to direct reflection dominating the captured signal, making it challenging to obtain subsurface information.
Innovation Solution
An apparatus and method using a rolling shutter with controlled aperture width, shutter scan speed, and time-variable electromagnetic radiation projection distribution to capture both directly reflected and subsurface-scattered radiation, minimizing direct reflection while maximizing subsurface scattering capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic radiation is projected onto the object, then the captured signal is dominated by directly reflected electromagnetic radiation, but it becomes challenging to obtain information about the subsurface structure
Solution Approach 1:
The patent applies dynamics by making the illumination distribution time-variable while keeping it spatially fixed. The illumination pattern changes over time during the rolling shutter exposure, creating temporal modulation that allows separation of direct reflection from subsurface scattering components through temporal filtering of the captured signal.
Solution Approach 2:
The patent implements periodic action through the time-variable illumination distribution that modulates the projected electromagnetic radiation in a periodic or pulsed manner during image capture. This periodic modulation enables the rolling shutter to distinguish between direct reflection and subsurface scattering based on their different temporal characteristics.
2Loss of information
If a rolling shutter with controlled aperture width and shutter scan speed is used, then both directly reflected and subsurface-scattered radiation can be captured, but the system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the aperture width and shutter scan speed of the rolling shutter before image capture. These parameters are set in advance to match the temporal characteristics of the time-variable illumination distribution, ensuring optimal separation of direct reflection and subsurface scattering without requiring real-time adjustment during capture.
Solution Approach 2:
The patent utilizes parameter changes by systematically adjusting the aperture width, shutter scan speed, and illumination timing parameters to optimize the capture of subsurface scattering. These parameter changes are coordinated to create a synchronized system where the rolling shutter exposure profile matches the illumination modulation, enabling effective subsurface imaging.
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
Enables the extraction of subsurface structure information by distinguishing and reducing direct reflection, allowing for detailed subsurface analysis and imaging.
Implementation Method 1
the majority of it is directly reflected from the surface of the object
Implementation Method 2
Information about the subsurface structure of an object can be obtained from electromagnetic radiation that has undergone subsurface scattering
Data Source
Figure 1~2
Figure 3~5C
Figure 6A~7C
AI summary
An apparatus (101) for obtaining information about a subsurface structure (119) of an object (113) is described. The apparatus comprises a projector (109) for projecting electromagnetic radiation (111) having a fixed-spatial and time-variable distribution onto the object, and a camera (103) having a rolling shutter with an aperture (105) width and a shutter scan speed for capturing directly reflected radiation (121) and subsurface scattered radiation (123) from the object, wherein the time-variable distribution of the projected electromagnetic radiation, the aperture width of the rolling shutter, and the shutter scan speed of the rolling shutter are such that adjustment of one or more of these would not decrease a proportion of projected electromagnetic radiation captured which is directly reflected from a surface of the object.