Signal Processing for Smooth Iris-Gain Brightness Switching
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Solution Overview
Problem
The abrupt change in brightness during switching between optical and electronic brightness adjustments causes discomfort and deteriorates operability due to differences in response characteristics between iris and gain, leading to resolution decrease.
Innovation Solution
A control unit implements a digital filter to delay the gain change, smoothing the transition between optical and electronic brightness adjustments by using a threshold value and delay characteristics to approximate iris response, thereby stabilizing brightness changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical brightness adjustment using iris is used, then brightness can be adjusted continuously, but resolution abruptly decreases when F value is excessively decreased
Solution Approach 1:
The system changes the control parameter from direct F value adjustment to adjusted F value calculation, where the iris opening is limited to a maximum threshold value and brightness adjustment is achieved through gain control instead of excessive iris opening, preventing resolution degradation
Solution Approach 2:
The gain control acts as an intermediary between the user's brightness indication and the final image brightness, allowing brightness adjustment without requiring the iris to open beyond the resolution-optimal range
2Adaptability or versatility
If switching between optical brightness adjustment and electronic brightness adjustment is performed, then brightness adjustment flexibility is improved, but a phenomenon that speed of change of brightness abruptly increases or decreases occurs
Solution Approach 1:
The system dynamically adjusts the maximum iris opening threshold and gain application based on the current brightness indication value, smoothly transitioning between optical and electronic brightness adjustment modes without abrupt changes in brightness change speed
Solution Approach 2:
The control unit changes the parameter for iris opening threshold and gain control based on the brightness indication value, ensuring continuous and smooth brightness adjustment characteristics across the entire adjustment range
3Illumination intensity
If gain is increased for electronic brightness adjustment, then brightness can be adjusted, but S/N ratio decreases
Solution Approach 1:
The system optimizes the gain control parameter by applying gain only when necessary (when brightness indication value is at or below threshold) and combining it with optimal iris opening, reducing the need for excessive gain increases that would degrade S/N ratio
4Illumination intensity
If iris is controlled for brightness adjustment, then optical brightness adjustment is achieved, but response characteristics differ from gain control causing switching issues
Solution Approach 1:
The control unit adjusts the maximum iris opening parameter based on the brightness indication value, and supplements with gain control when needed, creating a unified response characteristic that eliminates abrupt transitions during mode switching
Data Source
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AI summary
Mitigation of a discomfort of a user during brightness adjustment switching and curbing of deterioration in operability with respect to brightness adjustment are promoted while curbing of resolution decrease due to execution of only optical brightness adjustment is promoted. A switching unit that performs, in response to change in an indication value indicating the brightness of a captured image obtained by an imaging device, switching between optical brightness adjustment that is brightness adjustment according to an iris and electronic brightness adjustment that is brightness adjustment according to application of a gain depending on the indication value to the captured image, and a first delay unit that delays change in the gain with respect to change in the indication value in the electronic brightness adjustment are included.