Image Pickup Exposure Control Using Temporary Pixel Loading
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Solution Overview
Problem
Existing image pickup apparatuses take a long time to stabilize exposure when the subject brightness is extremely high or low, as they start feedback control from predetermined reference values or exposure information from previous photographs.
Innovation Solution
The apparatus temporarily loads a part of the image data from the sensor unit immediately after activation, using either thinning or cutting-out processing of pixel data, to set an optimum exposure value quickly, thereby shortening the time to stabilize exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is started from predetermined reference value or exposure information from previous photographing, then the system can maintain stability, but the time to stabilize exposure becomes extremely long when subject brightness is extremely high or low
Solution Approach 1:
The patent applies preliminary action by executing temporary loading of a part of image data immediately after activation, before the standard feedback control loop begins. This preliminary exposure value calculation using a subset of pixels provides a head start, allowing the system to converge to the correct exposure value faster without compromising final stability. The temporary loading occurs in advance of the normal operation sequence.
2Measurement precision
If all image data is loaded for exposure control, then accurate exposure value can be calculated, but the time to load and process image data increases
Solution Approach 1:
The patent applies segmentation by dividing the image data into parts and temporarily loading only a part of the pixel data for the initial exposure value calculation. This segmentation allows the system to obtain a sufficient exposure estimate using fewer pixels, significantly reducing the loading and processing time while still providing accurate enough information to start the feedback control process effectively.
Solution Approach 2:
The patent applies partial action by using only a part of the available image data (a subset of pixels) for the temporary exposure value calculation, rather than processing all image data. This partial processing is sufficient to establish an initial exposure value that accelerates the overall convergence, trading off some potential precision for significant speed improvement in the critical startup phase.
Data Source
AI summary
An exemplary aspect of the invention is an image pickup apparatus including a sensor unit including a plurality of pixels; an exposure control unit that controls exposure by a feedback control based on image data acquired by the sensor unit; and a display unit that displays an image having undergone exposure control. During a time period from a point immediately after activation of the image pickup apparatus until a point when an image is displayed on the display unit, the sensor unit executes temporary loading of a part of the image data, and the exposure control unit sets an optimum exposure value based on the image data temporarily loaded.