Reference Detector for Flicker Correction in Digital Imaging
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Solution Overview
Problem
Digital imaging systems face issues with undesirable artifacts due to illuminant intensity changes during image capture, such as flicker from light sources, leading to variations in brightness and horizontal bands in captured images, which existing methods only partially address.
Innovation Solution
Incorporating a reference detector proximal to the image sensor array to detect illuminant intensities and a processor to extract flicker correction parameters, synthesizing a flicker correction signal, and applying it to the digital image to compensate for illuminant intensity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rolling shutter technique is used to read the sensor array sequentially, then the image capture process is efficient and fast, but flicker artifacts and horizontal bands appear in the captured image due to illuminant intensity changes during the frame period
Solution Approach 1:
The patent applies preliminary action by detecting illuminant intensity changes during the exposure period before the image is fully captured. The system continuously monitors the illuminant intensity and stores these measurements, then uses this pre-captured information to correct the final image, preventing flicker artifacts from appearing in the output.
Solution Approach 2:
The patent implements feedback by using the detected illuminant intensity measurements to generate correction factors that are applied to the captured image rows. The system continuously monitors illuminant intensity during capture and uses this real-time information to adjust and correct the final image, creating a closed-loop system that eliminates flicker artifacts.
2Illumination intensity
If the exposure period is extended to capture more light, then image brightness is improved, but the duration of exposure increases the likelihood of illuminant intensity changes affecting different rows differently, worsening flicker artifacts
Solution Approach 1:
The system uses feedback by continuously monitoring illuminant intensity during the extended exposure period and using these measurements to generate row-specific correction factors. This allows the system to maintain longer exposure times for better brightness while compensating for illuminant changes that occur during this extended period.
Solution Approach 2:
The patent applies parameter changes by adjusting the illuminant intensity parameters detected during exposure to generate correction factors. By monitoring how illuminant intensity parameters change over time and applying these corrections to different rows, the system maintains optimal exposure settings while eliminating brightness variations caused by flicker.
3Measurement precision
If multiple measurements of illuminant intensity are taken during the frame period, then accuracy of flicker detection is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by taking multiple illuminant intensity measurements during the exposure period and storing them for later use. These pre-captured measurements are then used to generate correction factors, allowing accurate flicker detection without adding complex real-time processing requirements during image capture.
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
Effectively reduces flicker-related artifacts by accurately detecting and correcting for illuminant intensity changes, resulting in improved image quality by minimizing brightness variations and horizontal bands.
Implementation Method 1
Each sensor detects light from a tiny portion of the scene. At each sensor, the detected light is converted into an electrical signal
Data Source
AI summary
An apparatus such as a digital camera includes an image sensor array adapted to capture a scene into electrical values and a reference detector proximal to the sensor array for detecting illuminant intensities. The reference detector at least partially surrounds the image sensor array. The reference detector is read multiple times during the frame period in which the image sensor array captures a scene to detect illuminant intensities during the same frame period. Using the illuminant intensities, the phase and the amplitude of the flicker of the illuminant are extracted. Using the phase and the amplitude parameters, a flicker correction signal is synthesized. The flicker correction signal is used to correct the captured image data to reduce or eliminate adverse effects of flicker on the captured image.