Focus-Adjustment Signal Generation via High-Pass Filtering
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Solution Overview
Problem
Existing focus-adjustment signal generating apparatuses for cameras face challenges in generating accurate focus signals when the resolution of the video signal differs between image capture and display, leading to loss of high-frequency components and redundant system processing, making focus adjustments difficult and inaccurate.
Innovation Solution
A focus-adjustment signal generating apparatus that includes a filter to extract high-frequency components from the luminance signal, a comparator to determine if the absolute value exceeds a specific reference, and a selector to output either a chrominance difference signal indicating a specific color or an achromatic color, ensuring the focus-adjustment signal is generated without losing high-frequency components and reducing system redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focus-adjustment signal is generated after down-conversion to match VF/LCD resolution, then the signal can be displayed on the device, but high-frequency components are lost resulting in incorrect focus-adjustment signals
Solution Approach 1:
The patent applies preliminary action by generating the focus-adjustment signal before the down-conversion process. The high-pass filter processes the original high-resolution video signal to extract edge information, and the focus-adjustment signal is generated from this processed signal before it undergoes down-conversion. This ensures that high-frequency components are captured and preserved in the focus signal, preventing information loss while maintaining compatibility with the lower-resolution display device.
2Productivity
If RGB signals are used for focus-adjustment signal generation in later stage processing, then the signal can be generated using available processing stages, but system processing becomes redundant requiring an RGB converter
Solution Approach 1:
The patent applies the extraction principle by isolating and processing only the necessary luminance signal components for focus-adjustment generation, rather than processing the complete RGB signal sequence. The high-pass filter is applied specifically to the luminance signal to extract edge information, and the focus-adjustment signal is generated from this extracted information. This selective processing eliminates the need for redundant RGB conversion operations and reduces overall system processing complexity while maintaining functionality.
3Ease of operation
If edge processing is applied to enhance focus adjustment visibility on VF/LCD, then focus adjustment becomes easier, but the processing must be done after down-conversion which causes high-frequency component loss
Solution Approach 1:
The patent applies preliminary action by performing the high-pass filter processing and edge detection before the down-conversion process. The luminance signal is processed to extract high-frequency components and edge information in the original high-resolution domain, and the focus-adjustment signal is generated from this pre-processed information. This ensures that edge enhancement is achieved without the high-frequency component loss that would occur if processing were performed after down-conversion, thereby maintaining both ease of operation and signal integrity.
Data Source
AI summary
A focus-adjustment signal generating apparatus includes a filter to extract a high-frequency component at a specific frequency or higher from a luminance signal of an input video signal, a comparator to compare an absolute value of the high-frequency component with a specific reference value, to output a first detection signal when the absolute value is equal to or larger than the reference value whereas a second detection signal when the absolute value is smaller than the reference value, an extender to extend an output period of the first detection signal according to a period indicated by a period-length setting signal, to output an extended first detection signal, and a selector to select a first chrominance difference signal indicating a specific color in response to the extended first detection signal whereas a second chrominance difference signal indicating an achromatic color in response to the second detection signal, the first or the second chrominance difference signal being output as a focus-adjustment signal.