Zoom-Tracking Speed via Histogram-Based Locus Curve Selection
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Solution Overview
Problem
Zoom-tracking speed is reduced when zoom magnification changes to Tele during the zoom-tracking process, especially at low illuminance or in environments with spot light sources, due to inadequate focus lens movement and changing subject size and brightness.
Innovation Solution
An improved zoom-tracking method that involves choosing a Mid point between the Wide and Tele points, storing distance information as histogram data during auto-focusing, estimating subject distance using this data, and selecting a locus curve for zoom-tracking along the estimated distance, ensuring the focus lens moves efficiently even at high magnifications and varying light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the zoom lens moves from Wide point to Tele point during zoom-tracking, then the zoom magnification increases, but the zoom-tracking speed is reduced
Solution Approach 1:
The system performs auto-focusing in advance during the initial zoom range (first to second point) to obtain distance information and generate histogram data before reaching high magnification. This preliminary action allows the focus lens position to be predicted using the pre-acquired distance information and locus curve, avoiding time-consuming real-time adjustments during rapid zoom to Tele point
Solution Approach 2:
The system dynamically changes the zoom-tracking control strategy based on zoom magnification. At lower magnifications (first to second point), traditional auto-focusing is used to build distance information. At higher magnifications (second point to Tele point), the system switches to predictive control using pre-stored histogram data and locus curves, optimizing speed for each zoom stage
2Reliability
If the focus lens automatically moves to maintain focus during zoom, then focusing is achieved, but the zoom-tracking speed is reduced due to continuous focus adjustments
Solution Approach 1:
The system performs preliminary auto-focusing during the initial zoom phase to accurately determine subject distance and generate histogram data. This pre-acquired information is then used to predict focus lens positions during subsequent rapid zoom to Tele point, maintaining focusing accuracy without requiring continuous real-time adjustments
Solution Approach 2:
The histogram information and locus curve serve as intermediaries between the zoom lens position and the required focus lens position. Instead of directly controlling the focus lens based on real-time feedback during rapid zoom, the system uses these pre-computed intermediaries to predict and determine focus positions, enabling faster tracking while maintaining accuracy
3Measurement precision
If traditional auto-focusing is performed continuously during zoom to Tele point, then focus is maintained, but processing time increases and speed is reduced
Solution Approach 1:
The system performs subject distance measurement and histogram data acquisition in advance during the initial zoom range (first to second point). This pre-acquired distance information is then reused for predicting focus positions during the remainder of the zoom to Tele point, eliminating the need for continuous time-consuming measurements while maintaining precision
Solution Approach 2:
The system performs complete auto-focusing and distance measurement only partially (from first point to second point) rather than continuously throughout the entire zoom range. This partial action is sufficient because the pre-acquired data is extrapolated using locus curves to cover the remaining zoom range, reducing total processing time while maintaining measurement precision where needed
Data Source
AI summary
Provided is an improved zoom-tracking method. A point or two points between a Wide point and a Tele point are chosen, histogram information is stored, and a distance to a subject is estimated based on the stored histogram information. A locus curve is selected based on the estimated distance to the subject, and zoom-tracking is performed along the locus curve after a zoom lens reaches a specific point.