Smartphone Illuminance Model for Color Quantification in Uncontrolled Lighting
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Solution Overview
Problem
Existing luxmeter applications on portable electronic devices face limitations in accuracy due to restricted access to metadata and the use of external sensors, making precise illuminance measurements challenging, especially in uncontrolled lighting environments.
Innovation Solution
An illuminance model and additional measurements are introduced to enhance the accuracy of illuminance measurements and improve color quantification in digital photographs captured with portable electronic device digital cameras, allowing for use in medical devices under varying lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If luxmeter applications use standard digital camera sensors and metadata, then device complexity is reduced, but measurement precision deteriorates due to limited metadata access and uncontrolled lighting
Solution Approach 1:
The patent introduces a reference color chart as an intermediary object that mediates between the uncontrolled lighting environment and the measurement system. The chart contains known color values that serve as reference points, allowing the system to calculate illuminance and color temperature by comparing captured image data against these known references, thereby achieving precise measurements without requiring controlled lighting or complex external sensors
Solution Approach 2:
The system performs multiple measurements at different exposure times and combines the results to calculate illuminance and color temperature. By changing the exposure time parameter and aggregating data from multiple captures, the system overcomes the limitations of single-exposure metadata and achieves higher measurement precision while using only the standard camera sensor
2Measurement precision
If external sensors are used to improve illuminance measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the digital camera sensor perform multiple functions: it simultaneously captures color information, luminance information, and metadata that are all used for illuminance measurement. By utilizing the existing camera's multi-functional capabilities rather than adding dedicated external sensors, the system achieves high measurement precision while maintaining low device complexity
Solution Approach 2:
The system uses the camera's own metadata (exposure time, ISO, aperture) and captured image data to calculate illuminance and color temperature without requiring external calibration sensors. The camera essentially measures its own operating parameters and uses these self-generated data along with reference color chart comparisons to determine environmental lighting conditions
3Ease of operation
If metadata access is restricted by operating system limitations, then ease of operation is maintained, but measurement precision deteriorates
Solution Approach 1:
The system captures images at multiple exposure times (excessive action) rather than relying on a single standard exposure. This approach compensates for the limited metadata available from the camera by gathering more data than a single capture would provide, enabling precise illuminance calculation while still using only the standard camera interface and maintaining ease of operation
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
The proposed solution improves the accuracy of illuminance measurements and color quantification, enabling reliable use in medical devices across different lighting environments without the need for external sensors or controlled lighting.
Implementation Method 1
A digital image of the diagnostic instrument is captured using the camera sensor of a portable electronic device
Data Source
AI summary
In one embodiment, a diagnostic system for biological samples is disclosed. The diagnostic system includes a diagnostic instrument, and a portable electronic device. The diagnostic instrument has a reference color bar and a plurality of chemical test pads to receive a biological sample. The portable electronic device includes a digital camera to capture a digital image of the diagnostic instrument in uncontrolled lightning environments, a sensor to capture illuminance of a surface of the diagnostic instrument, a processor coupled to the digital camera and sensor to receive the digital image and the illuminance, and a storage device coupled to the processor. The storage device stores instructions for execution by the processor to process the digital image and the illuminance, to normalize colors of the plurality of chemical test pads and determine diagnostic test results in response to quantification of color changes in the chemical test pads.