Text Document Watermarking Using Stitched Character Images
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Solution Overview
Problem
Watermarking text-rich documents poses challenges such as increased document size, obstructed view, degraded image quality, and ink consumption due to methods like adding a tint or overlaying images, especially when converting back to the original document format.
Innovation Solution
A processor captures individual characters as images, groups them into a stitched image, embeds a watermark, and replaces original characters with these images to maintain document readability and reduce size and ink consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tint or overlay image is added to watermark a text document, then the document is protected with a watermark, but the document size increases and image quality degrades
Solution Approach 1:
The patent segments the document into individual character images rather than treating it as a continuous text flow. Each character is extracted, watermarked independently, and then reassembled. This segmentation allows for more efficient watermarking that doesn't require adding overlays to the entire document, thereby reducing document size while maintaining protection.
Solution Approach 2:
The patent applies different processing to different parts of the document - specifically, only the character images are watermarked and processed, while preserving the original document structure and non-character elements. This local approach to watermarking avoids the need for full-document overlays, reducing overall document size and maintaining quality.
2Reliability
If a tint or overlay image is added to watermark a text document, then the document is protected with a watermark, but the view of the document is obstructed
Solution Approach 1:
By segmenting the document into individual character images for watermarking purposes and then reassembling them, the patent avoids applying visual overlays that would obstruct the view. The segmentation approach allows watermark data to be embedded in the character image files themselves rather than as visible overlays on the document pages.
3Reliability
If a tint or overlay image is added to watermark a text document, then the document is protected with a watermark, but ink consumption increases when printing
Solution Approach 1:
The patent segments the document into individual character images that are watermarked at the image file level. When printed, only the necessary character images are output without requiring additional ink for full-page tints or overlay images. This segmentation approach significantly reduces ink consumption while maintaining watermark protection.
4Reliability
If the document is converted to image format for watermarking, then the watermark can be added, but lossy conversions occur when converting back to original format
Solution Approach 1:
The patent performs preliminary extraction of character images from the document in their original format, applies watermarking to these extracted images, and then reassembles them to recreate the document. This preliminary extraction and selective processing approach avoids repeated format conversions and the associated lossy compression that would degrade document quality.
Data Source
AI summary
According to examples, an apparatus may include a processor and a memory on which are stored machine-readable instructions that when executed by the processor, may cause the processor to extract text from a document. The processor may retrieve images associated with characters in the extracted text and generate a stitched image using the retrieved images. The processor may watermark the stitched image and replace the characters in the document with the images associated with the characters from the watermarked and stitched image.