Image Capturing Apparatus Flicker Detection and Frame Rate Control
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Solution Overview
Problem
Conventional digital cameras experience brightness/darkness flicker and horizontal stripes during movie capturing under fluorescent light, and struggle to maintain selected frame rates, leading to inconsistencies when playing back moving images on TV monitors via NTSC or PAL systems.
Innovation Solution
An image capturing apparatus with a mode changer and control unit that performs flicker detection based on specific control parameters for different image capturing modes, allowing for selection and control of image signal readout and frame rates, enabling arbitrary frame rates for movie recording and synchronized output with NTSC or PAL standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flicker detection is performed at a selected arbitrary frame rate during movie capturing, then the frame rate can be freely selected for recording, but it becomes difficult to perform flicker detection and control at the selected frame rate, causing brightness/darkness horizontal stripes to occur in the recorded moving image
Solution Approach 1:
The patent performs flicker detection at a predetermined frame rate (e.g., 30fps or 60fps) before actual movie recording begins. This preliminary detection allows the system to identify the flicker frequency of the lighting environment in advance, and then adjust the shutter speed accordingly to eliminate horizontal stripes. The actual recording can then proceed at any arbitrary frame rate without performing real-time flicker detection, thus resolving the contradiction between flexible frame rate selection and reliable flicker detection.
2Adaptability or versatility
If movie recording is performed at an arbitrary frame rate, then flexible frame rate selection is enabled, but the frame rate must be changed when outputting to TV monitors via NTSC or PAL systems, causing inconsistency between recording and playback frame rates
Solution Approach 1:
The patent separates the recording process from the output process. During recording, the system uses the originally detected shutter speed and operates at the selected arbitrary frame rate. When outputting to TV monitors, the system converts the frame rate to match the NTSC or PAL standard while maintaining the original shutter speed settings. This segmentation allows arbitrary frame rate selection during recording while ensuring frame rate consistency and compatibility during playback on standard equipment.
3Object-affected harmful factors
If the shutter speed is adjusted to eliminate flicker at a specific frame rate, then horizontal stripes are reduced, but the shutter speed becomes fixed and cannot be freely changed when switching between different image capturing modes
Solution Approach 1:
The patent implements a dynamic control system that automatically adjusts the shutter speed based on the currently active image capturing mode. When movie recording mode is selected, the system uses the shutter speed determined from preliminary flicker detection at the corresponding frame rate. When still image mode or other modes are selected, the system allows free shutter speed adjustment. This dynamic adaptation resolves the contradiction by making the shutter speed flexible rather than fixed, allowing optimal settings for each specific capturing mode.
Data Source
AI summary
An image capturing apparatus and its control method for capturing a moving image. Plural movie capturing modes with different control parameters are set in accordance with an instruction from a user. One of selectable frame rates is selected in accordance with video output setting by the user. Moving image frames are generated based on the selected frame rate and a control parameter corresponding to the frame rate, and recorded as a moving image on a recording medium.