Adaptive Illumination for Underwater Color Correction
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Solution Overview
Problem
Underwater photography and videography face challenges in capturing true color images due to wavelength-dependent losses as light propagates through water, with existing solutions being impractical for real-time adaptation to varying distances and environments.
Innovation Solution
An adaptive illumination system using a processor, range sensor, and multiple optical sources with unique spectra, which determines and adjusts optical power based on the range and depth to the underwater object, optimizing color quality factors for true color imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If white light illumination sources are used for underwater photography, then the imaging process is simple, but wavelength-dependent losses cause color distortion in the captured images
Solution Approach 1:
The illumination source is segmented into multiple independent light sources with different spectral characteristics (e.g., blue, green, red LEDs). Each source can be independently controlled to compensate for wavelength-dependent attenuation at different depths and ranges, enabling color correction without complex post-processing.
Solution Approach 2:
The spectral parameters of the illumination are dynamically changed based on the imaging conditions. The system adjusts the intensity and spectral composition of each light source according to the measured range and depth, optimizing the illumination spectrum to counteract water absorption characteristics at different propagation distances.
2Manufacturing precision
If colored filters are applied to the camera to compensate for wavelength-dependent loss, then color accuracy is improved, but the device complexity increases and real-time adaptation becomes impractical
Solution Approach 1:
Instead of filtering the captured light to correct color, the system inverts the approach by pre-compensating the illumination spectrum. The light sources are adjusted to emit the complementary spectrum that counteracts water absorption, so that the reflected light from the scene already contains the correct color information.
Solution Approach 2:
Multiple LED light sources with different spectral characteristics serve as intermediaries between the camera and the scene. These sources act as controllable spectral mediators that can be tuned to provide the appropriate illumination spectrum for different imaging conditions, eliminating the need for complex filter systems.
3Manufacturing precision
If different filters are used for different ranges, then color correction accuracy is improved, but the system cannot adapt to rapidly changing distances or remote locations
Solution Approach 1:
The illumination system is made dynamic through real-time control of multiple LED sources. A range-finding sensor continuously measures the distance to the scene, and the controller dynamically adjusts the intensity and spectral composition of each light source based on the measured range and depth, enabling continuous adaptation to changing imaging conditions.
Solution Approach 2:
The system implements a feedback loop where the range-finding sensor provides real-time distance information to the controller, which then adjusts the illumination parameters accordingly. This closed-loop control enables the system to automatically adapt to rapidly changing distances and maintain accurate color correction without manual intervention.
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 real-time color-corrected underwater imaging without the need for post-processing, suitable for various applications including photography, exploration, and monitoring, by compensating for wavelength-dependent losses in light propagation.
Implementation Method 1
A range sensor determines a range to an underwater object to be imaged
Implementation Method 2
Wavelength-dependent losses occur as the light propagates through water. Longer wavelengths (e.g., red light) attenuate more rapidly than shorter wavelengths (e.g., blue light). Absorption is the primary cause for loss in underwater propagation.
Data Source
AI summary
Described are a method and an apparatus for color-corrected underwater imaging. A range to an underwater object to be imaged is determined and control values are selected according to the range. Control values are predetermined for a number of ranges according to an optimization of a color quality factor for each range based on the spectra of the optical sources used for illumination and the wavelength-dependent optical transmission of the water for the range. The optical power of each optical source is controlled according to a respective one of the selected control values. Advantageously, an acquired image requires no color correction as the adaptive illumination compensates for the wavelength-dependent losses in the light propagation path from the optical sources to the object and from the object to the imaging device.