Copy-Forgery-Inhibited Pattern Density Compensation for Rotation
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Solution Overview
Problem
The existing copy-forgery-inhibited pattern image data density levels become uneven when rotated during image formation, affecting the visibility of embedded character strings and patterns, as the latent image and background portions do not maintain equal density levels, leading to a loss of the forgery-proof function.
Innovation Solution
An image processing apparatus and method that generates copy-forgery-inhibited pattern image data and rotates it according to a specific rotation angle, ensuring that the dot patterns in the latent image and background portions remain consistent and balanced, regardless of the rotation, by using dithering matrices and density level adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If copy-forgery-inhibited pattern image data is rotated during image formation, then the layout and orientation of the document can be adjusted, but the density levels of the latent image and background portions become uneven, causing the embedded character strings to become distorted or invisible
Solution Approach 1:
The patent applies preliminary action by pre-calculating and applying density compensation to the copy-forgery-inhibited pattern image data before rotation. The image processing apparatus determines the rotation angle in advance, calculates the required density adjustment for each pixel based on the rotation parameters, and applies this compensation beforehand. This ensures that after rotation, the latent image and background portions maintain equal density levels, preventing distortion or invisibility of embedded character strings.
2Reliability
If the density levels of latent image and background portions are kept equal in the original image, then the copy-forgery-inhibited pattern functions correctly, but rotation causes the density levels to become uneven, affecting the visibility of embedded information
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the density parameter of the copy-forgery-inhibited pattern image data based on the rotation angle. The image processing apparatus calculates compensation values that depend on the rotation parameters and applies these to modify the density distribution. This ensures that even after rotation, the density levels remain consistent between latent image and background portions, maintaining the reliability of the copy-forgery-inhibited function.
3Ease of manufacture
If dithering processing is used to create the copy-forgery-inhibited pattern, then the pattern can be generated, but rotation causes the dot patterns to become misaligned, leading to density fluctuations
Solution Approach 1:
The patent applies preliminary action by pre-calculating the density compensation values based on the rotation angle before the actual rotation occurs. The image processing apparatus determines the rotation parameters in advance, calculates the compensation matrix that will maintain dot pattern alignment after rotation, and applies this compensation to the dithered image data. This preliminary preparation ensures that when rotation is performed, the dot patterns remain properly aligned and density fluctuations are prevented.
Data Source
AI summary
In prior art, there are some occasions where functions of a copy-forgery-inhibited pattern are impaired when printed on a sheet after rotation because of the level difference appearing between the density level of a latent image portion and the density level of a background portion of a copy-forgery-inhibited pattern. To cope with the problem, the image processing apparatus which has a generating unit for generating copy-forgery-inhibited pattern image data and a rotation unit for rotating the generated copy-forgery-inhibited pattern image data, wherein the generating unit generates the copy-forgery-inhibited pattern image data to be rotated by the rotation unit in accordance with a rotation angle in the rotation unit.