Imaging Device Signal Correction for Ghost and Flare
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Solution Overview
Problem
Existing imaging devices using phase difference AF methods face challenges in maintaining image quality due to ghost or flare effects, which can lead to inaccurate focus detection and reduced precision, especially when strong light sources are present, as they often require gain correction that increases noise and introduces correction errors.
Innovation Solution
An imaging device and signal correcting method that determine the presence of ghost or flare effects and selectively apply interpolation or gain correction processing to focus detecting pixel cells, using a determining unit to assess the need for correction based on signal differences and generate corrected image data without deteriorating image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain correction processing is applied to focus detecting pixel cells to correct sensitivity differences, then the output signal accuracy is improved, but noise is amplified and correction errors increase
Solution Approach 1:
The patent applies different correction strategies to different regions of the image sensor. Normal pixel cells use gain correction processing to correct sensitivity differences, while focus detecting pixel cells affected by ghost or flare use interpolation correction processing. This local differentiation allows the system to maintain output signal accuracy where possible while avoiding noise amplification in problematic regions.
Solution Approach 2:
The patent uses normal pixel cells as intermediary reference points to correct focus detecting pixel cell signals through interpolation. Instead of directly amplifying the noisy focus detecting pixel cell signals with gain correction, the system uses the cleaner signals from surrounding normal pixel cells as intermediaries to reconstruct the focus detection data, thereby avoiding direct noise amplification.
2Reliability
If interpolation correction processing is used to create output signals for focus detecting pixel cells, then noise amplification is avoided, but the correction precision may be insufficient compared to gain correction
Solution Approach 1:
The patent implements a conditional correction strategy where the correction method is locally optimized based on the specific conditions of each pixel cell. When ghost or flare is detected in a focus detecting pixel cell, interpolation correction is applied to maintain image quality. When such conditions are absent, gain correction is used to achieve higher correction precision. This local adaptation resolves the contradiction by allowing each region to use the most appropriate correction method.
3Measurement precision
If focus detecting pixel cells with smaller opening areas are used to enable phase difference AF, then focus detection capability is improved, but the cells generate insufficient imaging signals requiring correction
Solution Approach 1:
The patent makes normal pixel cells multi-functional by using them both for their primary imaging function and as reference signals for correcting focus detecting pixel cells. Through interpolation correction, the normal pixel cells serve dual purposes: capturing the main image and providing reference data to reconstruct focus detection signals, thereby compensating for the insufficient imaging signal strength in focus detecting pixel cells without requiring additional hardware.
4Measurement precision
If ghost or flare correction is applied to improve phase difference AF precision, then focus detection accuracy is improved, but the determination and correction process increases device complexity
Solution Approach 1:
The patent performs preliminary determination of ghost or flare presence using the captured image signal before applying correction processing. By detecting the presence of ghost or flare effects in advance through analysis of the image signal characteristics, the system can selectively apply interpolation correction only where needed, rather than universally correcting all focus detecting pixel cells. This preliminary action simplifies the overall correction process by avoiding unnecessary corrections in regions without ghost or flare.
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 method effectively reduces correction errors and maintains image quality by applying appropriate correction processing, improving focus detection precision and overall image quality even in the presence of ghost or flare effects.
Implementation Method 1
a plurality of pairs configured by plural types of second pixel cells for focus detection which receive light passing through different pupil regions of a photographing lens
Data Source
AI summary
A digital signal processing unit 17 of a digital camera which includes a solid-state imaging element 5 having an imaging pixel cell 30 and a pair of focus detecting pixel cells 31R and 31L determines whether a captured image signal obtained by imaging by the imaging element 5 has a region affected by at least one of the flare and the ghost. And, when it is determined that there is the region, the digital signal processing unit 17 performs correction processing by signal interpolation using an output signal of imaging pixel cells around the focus detecting pixel cell included in the captured image signal on an output signal of all the focus detecting pixel cells included in the captured image signal.