PDF Artwork Edge Smoothing for Robust Signal Embedding
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Solution Overview
Problem
Existing technologies face challenges in efficiently encoding information signals within host carriers like color artwork and images, particularly in printed objects such as product packaging, labels, and hangtags, without compromising perceptual quality or robustness.
Innovation Solution
The described technology involves an image processing method that embeds a signal into a PDF file by converting vector elements into raster elements with saw-tooth edges, embedding the raster elements with a plural-bit payload, and layering the vector elements under the embedded raster elements, while establishing a keep-a-way zone and eroding the saw-tooth edges to obscure the signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If vector elements are converted into raster elements with saw-tooth edges for signal embedding, then signal encoding capability is improved, but visual quality and edge smoothness deteriorate
Solution Approach 1:
The patent segments the edge processing into multiple stages: original vector conversion to raster, saw-tooth edge creation for signal embedding, and subsequent smoothing operations. This segmentation allows the signal encoding function and visual quality function to operate at different stages without interfering with each other, resolving the contradiction between signal encoding capability and edge smoothness.
Solution Approach 2:
The patent applies preliminary smoothing actions by creating a smoothed version of the raster element before final composition. The smoothed raster element is then used to obscure the saw-tooth edges while preserving the embedded signal, thus preliminarily preparing the visual quality without compromising the encoding capability.
2Reliability
If saw-tooth edges are used in raster elements, then signal embedding robustness is improved, but perceptual quality deteriorates
Solution Approach 1:
The patent introduces a vector element as an intermediary layer between the saw-tooth raster element and the final output. This vector element serves as a mediator that obscures the harmful saw-tooth edges while allowing the embedded signal to pass through, thus resolving the contradiction between robustness and perceptual quality.
Solution Approach 2:
The patent applies different quality treatments to different parts of the image: the saw-tooth edges are preserved in regions where signal embedding is needed, while smoothed versions are applied in regions where visual quality is prioritized. This local differentiation resolves the contradiction by allowing both robustness and perceptual quality to coexist in different locations.
3Loss of information
If signal components are embedded in raster elements, then information encoding capability is improved, but visual artifacts increase
Solution Approach 1:
The patent extracts the signal embedding function from the visual display function by using separate layers: the raster element carries the embedded signal while the vector element carries the visual appearance. This extraction removes the harmful visual artifacts from the final output while preserving the information encoding capability in the raster layer.
Data Source
AI summary
The present disclosure relates generally to signal encoding for elements within PDF files. One implementation smooths saw-toothed edges of rasterized elements meant for encoding. Other implementations are provided too.