Imaging Device Non-Linear Sensor High Dynamic Range
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Solution Overview
Problem
Conventional imaging devices struggle to generate suitable color images in scenes with extreme contrast between light and shade, leading to issues like blown-out highlights and blocked-up shadows, and fail to ensure color reproducibility consistent with human vision characteristics.
Innovation Solution
The imaging device employs a non-linear image sensor with a plurality of filters arranged in a specific pattern, transforming non-linear output signals into linear ones, interpolating missing color signals, and separating near-infrared components to combine linear color signals with non-linear luminance signals, preventing blown-out highlights and ensuring high color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a general image sensor is used in high dynamic range scenes, then the device complexity is low, but the measurement precision deteriorates due to blown-out highlights and blocked-up shadows
Solution Approach 1:
The patent segments the dynamic range by using multiple pixels with different sensitivity characteristics (first pixels for high luminance, second pixels for low luminance). This allows simultaneous capture of both bright and dark regions without information loss, resolving the contradiction between image quality and processing complexity by dividing the measurement task across specialized sensors.
Solution Approach 2:
The patent changes the sensitivity parameter of different pixels to match different luminance ranges. First pixels have sensitivity optimized for high luminance regions while second pixels are optimized for low luminance regions. This parameter differentiation allows the system to maintain high measurement precision across the entire dynamic range without requiring complex post-processing.
2Productivity
If signal bit width is narrowed in signal processing, then the productivity is improved, but the loss of information increases in low luminance portions
Solution Approach 1:
The patent applies local quality by using second pixels with enhanced sensitivity specifically for low luminance regions. These pixels maintain higher bit width information for dark areas while first pixels can use reduced bit width for bright areas. This localized optimization allows efficient processing overall while preserving critical low luminance information that would otherwise be lost.
3Reliability
If an IR color camera is used to improve monitoring performance in darkness, then the reliability is improved, but the measurement precision deteriorates due to near-infrared light interference
Solution Approach 1:
The patent extracts and removes the near-infrared light component from the signal processing pipeline. By explicitly identifying and eliminating this interfering wavelength range, the system maintains the reliability benefit of IR sensitivity for darkness monitoring while restoring color measurement precision by preventing NIR contamination from affecting color accuracy.
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
This approach effectively generates color images without blown-out highlights or blocked-up shadows, maintaining color reproducibility consistent with human vision even in high dynamic range scenarios.
Implementation Method 1
an image sensor which expands a dynamic range by allowing a relationship between input luminance and an output signal to have a non-linear characteristic
Implementation Method 2
three types of filters which selectively transmit light of a visible light region different from each other
Implementation Method 3
the near-infrared light component is separated, and a luminance signal which varies non-linearly in accordance with luminance of each incident light is generated
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
Even in a case of photographing a photographic subject in which contrast between light and shade is large, a suitable color image is generated. An image sensor (102) includes a plurality of pixels on which three types of filters (R, G, B) which selectively transmit light having different wavelengths and have transmittances equal to each other in a visible light region and a clear filter (C) in which a transmittance of the visible light region is expressed by a linear sum of the transmittances of the filters (R, G, B) and which has a transmittance equal to the transmittances of the filters (R, G, B) in a near-infrared light region are arranged, and outputs a first output signal (S1), an output signal linear-transforming part (104) transforms the first output signal (S1) into a second output signal (S2) having linearity, a color signal-generating part (105a) generates color signals by interpolating lacking color signals, an infrared-separating part (1053a) separates a near-infrared light component from the color signals and generates infrared-separated color signals, a luminance signal-generating part (107) generates a luminance signal (Y1) from the first output signal (S1), and a color-luminance-combining part (109) combines the infrared-separated color signals and the luminance signal (Y1) and generates video signals (R2, G2, B2).