Quadrangular Image Focus Adjustment for Keystone Correction
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Solution Overview
Problem
Existing image photographing methods for mobile devices struggle with maintaining high image precision when correcting rectangular documents, particularly when the oblique angle between the object plane and imaging plane is large, leading to keystone distortion and poor user experience due to uneven resolution in the corrected image.
Innovation Solution
An image photographing method that selects specific focuses within a quadrangular image to capture initial images with higher resolution for regions that would otherwise be blurry, adjusting these images to rectangular format, and combining them to enhance overall image definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If keystone correction is performed on a quadrangular image with large oblique angle, then the rectangular document can be corrected, but the definition of the far end region decreases significantly
Solution Approach 1:
The patent applies preliminary action by performing a first focus adjustment before the standard focus adjustment. The method detects the oblique angle of the quadrangular image, determines a first focus position based on this angle, and performs focus adjustment at this position before the normal focus adjustment. This preliminary focus adjustment ensures that the far end region has sufficient clarity before keystone correction is applied, preventing the definition loss that would otherwise occur in the corrected image.
2Area of stationary object
If the oblique angle between object plane and imaging plane is large, then more of the rectangular target can be captured, but not all parts are within the depth of field range
Solution Approach 1:
The patent applies local quality by implementing different focus adjustment strategies for different regions of the image. Instead of using a uniform focus adjustment, the method calculates a first focus position specifically tailored to the oblique angle and quadrangular characteristics, then performs a region-specific focus adjustment before the standard focus adjustment. This ensures that the far end region, which would otherwise be out of focus, receives appropriate focus treatment while maintaining overall image quality.
Data Source
AI summary
An image photographing method is provided, including: based on a photographing instruction, selecting at least one focus in a quadrangular image, and photographing at least one initial image based on the at least one focus, where the quadrangular image includes a first pair of opposite sides and a second pair of opposite sides, an included angle between the opposite sides of the first pair of opposite sides is less than that of the second pair of opposite sides, a first side is a shorter side of the first pair of opposite sides, the at least one focus includes a first focus, and the first focus is in the quadrangular image and in a partial region including the first side; adjusting a quadrangular image to a rectangular image; and obtaining a final image and outputting the final image.