Tint Block Image Generation Using Common Displacement Vectors
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Solution Overview
Problem
Existing forgery-inhibited tint block technologies face challenges in maintaining high concealment capability for the original while increasing the identification capability of the latent image in copies, due to limitations in dot size and screen ruling differences between the latent image and background portions, which lead to density unevenness and reduced concealment.
Innovation Solution
A tint block image generation method that arranges first dots in the latent image portion and second dots in the background portion on common displacement vectors, with the background portion comprising large second dots and micro third dots, allowing for increased output density without high screen ruling, thereby enhancing the identification capability in copies while maintaining concealment in originals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high screen ruling is used to create dispersed dots in the background portion, then the identification capability in copies is improved, but density unevenness occurs and concealment capability deteriorates
Solution Approach 1:
The patent changes the screen ruling parameter from high to low (60 lpi or lower) in the background portion, which transforms the dot arrangement from dispersed to clustered. This parameter change allows the background portion to maintain density consistency with the latent image portion while still achieving identification capability through the clustered dot pattern that reproduces well in copies.
2Manufacturing precision
If low screen ruling is used to create clustered dots in the latent image portion, then the concealment capability is improved, but the identification capability in copies deteriorates
Solution Approach 1:
The patent applies different dot arrangement qualities to different portions: the latent image portion uses clustered dots (low screen ruling) for concealment, while the background portion also uses clustered dots (low screen ruling) but with different density characteristics. This local quality differentiation allows each portion to fulfill its specific function while maintaining overall system performance.
Solution Approach 2:
The patent changes the screen ruling parameter to 60 lpi or lower for the background portion, which is lower than conventional values. This parameter change enables the background portion to produce clustered dots that maintain density consistency with the latent image portion, thereby achieving both concealment capability and identification capability in copies.
3Measurement precision
If dispersed dots are used in the background portion, then the identification capability is improved, but density unevenness and reduced concealment occur
Solution Approach 1:
The patent changes the dot arrangement from dispersed to clustered by using low screen ruling (60 lpi or lower) in the background portion. This parameter change stabilizes the density composition of the background portion, making it consistent with the latent image portion and preventing density unevenness, while still achieving identification capability through the clustered pattern reproduction in copies.
4Measurement precision
If high output density is achieved using high screen ruling, then the identification capability is improved, but the device complexity and density unevenness increase
Solution Approach 1:
The patent changes the screen ruling parameter from high to low (60 lpi or lower) in the background portion, simplifying the device requirements while maintaining high output density. This parameter change reduces the complexity of the printing system and eliminates density unevenness associated with high screen ruling, while still achieving identification capability through the clustered dot pattern that reproduces effectively in copies.
Data Source
AI summary
A computer readable storage medium stores a tint block image generation program for generating tint block image data for forming, on a print medium, a tint block image including a latent image portion which is reproduced by copying, and a background portion of which copy output density drops. The program has a latent image portion generation step of generating data of a plurality of first dots in the latent image portion based on a dot clustered screen; and a background portion generation step of generating data of a plurality of second dots and data of a plurality of third dots dispersed among the second dots and having a size smaller than the second dots. And the first dots in the latent image portion and the second dots in the background portion are arranged at positions on common displacement vectors in an area of the tint block image.