Cigarette Pack Imprint Inspection Using Virtual Reference Image Comparison
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Solution Overview
Problem
Existing methods for automatically applying and inspecting imprints on cigarette packs struggle with complex typefaces, particularly Asian characters, requiring extensive training and failing to accurately recognize and correct errors in real-time production.
Innovation Solution
A method that generates a virtual reference image using graphic data to compare with actual test images, allowing for pixel-based analysis without the need for specific character recognition training, and includes integration of background image data to match production conditions, enabling real-time error detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OCR-based text recognition is used to inspect imprints, then the system can identify printed text, but it fails to accurately recognize complex typefaces such as Asian characters without extensive training
Solution Approach 1:
The patent replaces the OCR-based text recognition system with a direct image comparison system. Instead of using optical recognition algorithms that struggle with complex characters, the system captures an image of the actual imprint and compares it pixel-by-pixel with a reference image, eliminating the need for character-specific recognition capabilities while maintaining high accuracy for any typeface
Solution Approach 2:
The patent creates a digital copy (reference image) of the ideal imprint and uses this copy for direct visual comparison with the actual imprint. This approach bypasses the need for text recognition entirely, as the system compares the visual appearance of the imprint against its reference copy, enabling accurate inspection of any character type without specialized training
2Reliability
If a reference package with reference imprint is used to teach the test system, then the system can be trained to recognize imprints, but the training process becomes extremely challenging when typefaces become more complex
Solution Approach 1:
The patent replaces the complex training and teaching process with a straightforward reference image comparison approach. Instead of training an OCR system to recognize various typefaces, the system simply stores a reference image of the correct imprint and compares actual imprints against this reference, eliminating the need for extensive training while maintaining high reliability
Solution Approach 2:
The patent uses a digital copy of the reference imprint stored in the control unit for direct comparison. This reference copy serves as the ground truth against which all actual imprints are measured, providing reliable recognition without requiring the system to be 'taught' how to recognize different typefaces
3Measurement precision
If the test image includes background areas of the print medium, then the comparison can account for background variations, but the image analysis becomes more complex
Solution Approach 1:
The patent segments the image analysis process into two distinct phases: first capturing the complete test image including background, then using image processing to isolate and extract only the imprint region for comparison. This segmentation allows the system to benefit from including background information while managing analysis complexity by focusing computational resources only on the relevant imprint area
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient recognition and correction of imprint errors on cigarette packs without requiring special training for complex characters, allowing for inline quality control and adaptive printing adjustments based on detected print medium characteristics.
Implementation Method 1
a laser printer
Implementation Method 2
a camera
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for automatically applying imprints to print carriers (17) used in the production and/or packaging of cigarettes, in particular to cigarette packs (10) or blanks for cigarette packs, and for subsequently automatically checking the imprints (12a-12c) by optical means, in the case of which, during the production and/or packaging process, the respective imprint (12a-12c) is applied to the print carrier (17) by means of a printing unit (11), in particular a laser printer, and at least one checking image (15) containing the imprint (12a-12c) applied is taken using a checking means (13), in particular a camera. The invention is characterized in that a virtual reference image (16) containing the imprint (12a-12c) is generated on the basis of graphic data, in particular vector graphic data, describing the imprint (12a-12c) which is to be applied, and in that the virtual reference image (16) is compared with the checking image (15) taken by the checking means (13).