Digital Watermark Reading via Multi-Image Selection and Stitching
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Solution Overview
Problem
Conventional techniques for reading digital watermarks from print products fail to capture the entire embedded area accurately when the camera is moved by hand, often resulting in blurred images due to camera shake and changing distances, which cannot be effectively addressed.
Innovation Solution
An image processing apparatus that captures multiple areas of the print product under different conditions, selects the best image for watermark extraction, and uses focus or F-number bracket shooting to ensure clarity, employing super-resolution processing to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the entire digital watermark-embedded printed area is captured by one shooting, then the watermark reading accuracy is improved, but the device complexity increases requiring specialized equipment
Solution Approach 1:
The patent divides the large printed area into multiple smaller capture regions that can be photographed separately by a standard camera. The captured images are then stitched together to form a complete view of the entire watermark-embedded area, enabling accurate watermark reading without requiring specialized high-complexity equipment.
Solution Approach 2:
The patent introduces the time dimension by capturing multiple images sequentially and combining them. Instead of attempting to capture the entire area in a single static shot, the system uses multi-temporal image capture and synthesis to achieve comprehensive coverage and maintain reading accuracy.
2Ease of operation
If the user captures the print product while moving the image capturing device by hand, then the ease of operation is improved, but the image quality deteriorates due to camera shake and out-of-focus
Solution Approach 1:
The patent employs focus detection feedback mechanisms that analyze the captured images and determine whether they are in focus. Based on this feedback, the system automatically adjusts focusing parameters or selects the best-focused images from the sequence, ensuring image quality even when the camera is moved by hand during continuous shooting.
Solution Approach 2:
The patent dynamically changes capturing parameters such as focus distance, aperture (F-number), and shutter speed during the capturing process. By adjusting these parameters in response to detected focus conditions and movement, the system maintains image quality while allowing handheld operation flexibility.
3Manufacturing precision
If focus bracket shooting or F-number bracket shooting is performed, then the image quality is improved by reducing out-of-focus, but the capturing time increases
Solution Approach 1:
The patent performs focus bracket shooting or F-number bracket shooting selectively based on detected focus conditions rather than for every image. When the system detects that the current image is adequately in focus, it skips additional bracket shots, thereby reducing total capturing time while still ensuring image quality when needed.
Data Source
AI summary
An image processing apparatus obtains information of a digital watermark based on an image obtained by causing an image capturing device to capture a print product in which the digital watermark is embedded. An image capturing unit is configured to cause the image capturing device to capture a plurality of areas on the print product by repeating continuous shooting a plurality of times under a plurality of image capturing conditions. A selection unit is configured to select, from a plurality of images obtained by the plurality of times of the continuous shooting by the image capturing unit, an image from which the information of the digital watermark is to be obtained. An obtaining unit is configured to obtain the information of the digital watermark based on the image selected by the selection unit from the plurality of images obtained by the respective times of the continuous shooting by the image capturing unit.