Focus Assist Image Generation for Low Contrast Subjects
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Solution Overview
Problem
Existing imaging apparatuses with manual focus functions struggle to accurately distinguish between in-focus and defocused states, particularly for low contrast subjects, as the first focus evaluation value alone is insufficient to determine focus, leading to incorrect bar displays indicating focusing state.
Innovation Solution
The imaging apparatus calculates a second focus evaluation value based on contrast, which determines the degree of defocus, and generates a focus assist video image by overlaying this evaluation on the image signal, allowing only nearly in-focus subjects to display a focus indicator, thereby improving focus adjustment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a first focus evaluation value is calculated from image signal to indicate focusing degree, then focus evaluation can be performed, but the evaluation value cannot accurately distinguish between in-focus and defocused states for low contrast subjects
Solution Approach 1:
The patent introduces a second focus evaluation value based on contrast as an additional parameter. By combining the first focus evaluation value (from image signal) with the second focus evaluation value (from contrast), the system achieves more accurate focus state distinction, particularly for low contrast subjects where the first evaluation value alone was insufficient.
2Ease of operation
If focus evaluation value is displayed on the finder to support manual focus, then user can adjust focus, but incorrect bar displays appear for defocused areas including low contrast subjects
Solution Approach 1:
The system uses the combined first and second focus evaluation values to generate accurate focus indicator bars that provide reliable feedback to the user. The second focus evaluation value (contrast-based) serves as a corrective feedback mechanism that prevents incorrect bar displays for defocused areas, ensuring users receive accurate information about actual focus state.
3Quantity of substance
If focus indicator bars are displayed for all blocks to show focus status, then complete focus information is provided, but defocused areas including low contrast subjects show incorrect indicators
Solution Approach 1:
The patent applies parameter changes by introducing a second focus evaluation value based on contrast. This new parameter enables the system to distinguish between truly in-focus areas and defocused areas that may have appeared in-focus with the first evaluation value alone. As a result, focus indicator bars are selectively displayed only for blocks that meet the combined evaluation criteria, ensuring high precision in focus state detection.
Data Source
AI summary
The imaging apparatus of the present technique is provided with an imaging unit configured to generate an image signal from a subject; and an evaluation value calculator configured to calculate an evaluation value that indicates a degree of focusing on the subject from the image signal obtained by the imaging unit for each block, and to output the evaluation value. The imaging apparatus is further provided with a combining unit configured to generate a focus assist video image based on the focus evaluation value, output from the evaluation value calculator, of each block, to combine the generated assist video image with the image signal, and to output the assist video image combined with the image signal; and a display unit configured to display an image in which the assist video image combined by the combining unit is combined.