PDF Trapping via Colored Tiling Pattern and Clipping
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Solution Overview
Problem
Current methods for creating PDF trapping objects are limited by the requirement for contour descriptions, which are not always available, especially for fonts like 'Multiple Master' fonts, making it difficult to implement choking effects in PDF files without manual intervention or embedded font data.
Innovation Solution
A method that generates PDF trapping objects using stroke and clip commands by creating a colored tiling pattern from the PDF page description, allowing for choking of text objects without knowing their contour descriptions, and using this pattern to create an inner frame and overprint background colors for trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contour descriptions are used to create trapping objects, then trapping precision is improved, but the method becomes inapplicable when fonts are not embedded or available
Solution Approach 1:
The patent extracts the essential function of contour description by using the text object itself as a clipping mask, eliminating the dependency on external contour data. The text object's inherent bounding box and glyph shapes provide sufficient information for creating the inner frame without requiring font embedding or separate contour files.
Solution Approach 2:
The patent introduces a colored tiling pattern as an intermediary element that bridges the gap between available PDF data and the required trapping effect. This pattern serves as a mediator that can be applied through stroke commands to achieve the choking effect without direct contour information.
2Manufacturing precision
If manual trapping intervention is used, then trapping quality is improved, but productivity and automation are reduced
Solution Approach 1:
The system performs trapping automatically by utilizing the text object's own properties (bounding box, glyph shapes) to generate the inner frame. The process is self-sufficient, requiring no manual intervention or external contour data, thereby maintaining high trapping quality while achieving full automation.
Solution Approach 2:
The patent changes the approach from using external contour parameters to using intrinsic text object parameters (bounding box coordinates, glyph metrics). This parameter transformation enables automated processing while maintaining trapping quality, as the text object's own data suffices for generating accurate trapping frames.
3Productivity
If stroke and clip commands are used without contour descriptions, then automation and productivity are improved, but the ability to create accurate inner frames is worsened
Solution Approach 1:
The patent extracts the necessary geometric information directly from the text object's bounding box and glyph data that is already present in the PDF. By taking out and utilizing this inherent information, the method achieves both automation and accuracy without requiring external contour descriptions.
Solution Approach 2:
The method creates a copy of the text object's visual representation through the colored tiling pattern applied via stroke commands. This copying approach preserves the visual accuracy of the inner frame while enabling automated processing, as the pattern replicates the text's appearance without needing separate contour data.
Data Source
AI summary
A method for creating PDF trapping objects from a PDF page description without a known contour description by using a computer for a printing process includes using the computer to generate a colored tiling pattern out of a part of the PDF page description without the top object to be choked, using the computer for clipping with a mask of the background object, using the computer for clipping with the top object or text to limit following frame additions to the top object, using the computer for adding a frame to the top object, using the generated colored tiling pattern as an inner frame between the background object and the top object, using the computer for adding a frame to the top object while activating overprinting of the background in the required object colors and using the computer for inserting the trapped top object into the PDF page description.