Watermark Embedding in Cinema Signals via Luminance Segmentation
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Solution Overview
Problem
Existing watermark embedding schemes for cinema movies are not robust enough to withstand de-flickering operations, as tools designed to remove flicker caused by frame rate mismatches and scan format differences also remove the embedded watermark.
Innovation Solution
The method divides each image into two areas and embeds a watermark by oppositely modulating the mean luminance of these areas, ensuring that the watermark information is retained even when de-flickering tools adjust the mean luminance of successive images, and repeats the watermark sample across consecutive frames to reduce flicker visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the watermark is embedded by modulating the global property (mean luminance) of the entire image, then the watermark can be detected in copies made by handheld video cameras, but de-flickering tools will remove the embedded watermark
Solution Approach 1:
The patent divides each image into multiple distinct image areas (e.g., left and right halves, or upper and lower halves) and embeds the watermark by modulating the mean luminance of these segmented areas in opposite directions. This segmentation prevents de-flickering tools from removing the watermark, as they operate on the entire image uniformly and cannot distinguish between the watermarked areas and the rest of the image.
Solution Approach 2:
The patent applies local quality by embedding the watermark in specific localized regions of the image rather than uniformly across the entire image. By modulating the mean luminance of distinct image areas in opposite directions, the watermark becomes embedded in the local structure of the image, making it resistant to global de-flickering operations while maintaining detectability.
2Object-affected harmful factors
If the same watermark sample is embedded in multiple consecutive images to reduce flicker visibility, then the flicker becomes imperceptible to the human eye, but the watermark becomes more vulnerable to de-flickering operations
Solution Approach 1:
The patent segments the image into multiple areas and embeds the watermark in opposite directions in each segment. This segmentation approach allows the watermark to be repeated across consecutive frames (to reduce flicker visibility) while maintaining robustness against de-flickering operations, as the opposite modulation in different segments prevents uniform removal by de-flickering tools.
3Reliability
If the watermark is embedded using only the temporal axis as in prior-art methods, then robustness to geometric distortions is achieved, but the watermark is vulnerable to de-flickering operations
Solution Approach 1:
The patent transitions from embedding the watermark using only the temporal axis (one dimension) to embedding the watermark in multiple spatial regions simultaneously (adding spatial dimension). By modulating the mean luminance of distinct image areas in opposite directions, the watermark gains robustness against both geometric distortions and de-flickering operations, as the spatial distribution of the watermark prevents uniform removal by de-flickering tools.
Data Source
AI summary
Methods and arrangements are disclosed for embedding and detecting a watermark in a cinema movie, such that the watermark can be detected in a copy made by a handheld video camera. The watermark embedder divides each image frame into two areas. A watermark bit ‘+1’ is embedded in a frame by increasing the luminance of the first part and decreasing the luminance of the second part. A watermark bit ‘−1’ is embedded by decreasing the luminance of the first part and increasing the luminance of the second part. It is achieved with the invention that the embedded watermark survives ‘de-flicker’ operations that are often used to remove flicker caused by the different frame rates of cinema projection equipment and consumer camcorders.