Image Encryption via Block Rearrangement and Selective Pixel Conversion
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Solution Overview
Problem
Conventional image processing technologies for encrypting printed materials face challenges in accurately decrypting images that have been degraded through printing or scanning, particularly due to issues with block positioning and pixel value conversion, leading to blurs and incomplete reproduction of images with multiple tones.
Innovation Solution
An image processing method that sections an image into blocks, rearranges them based on an encryption key, and converts pixel values within minimum areas using a computing method determined by statistical characteristics of proximate pixels, allowing for precise decryption and reduction of image degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If black-and-white reversing or mirror reversing is applied to encrypt image blocks, then encryption is achieved, but black pixels increase causing blurs in printing
Solution Approach 1:
The patent applies different processing methods to different parts of the image. Instead of uniformly reversing all blocks, it selectively processes only those blocks containing specific information (such as text or important data), leaving other blocks unchanged. This local differentiation prevents unnecessary black pixel generation and reduces printing blurs while maintaining encryption effectiveness for critical information.
Solution Approach 2:
The patent changes the encryption approach from simple black-and-white reversing to more sophisticated pixel value transformations. By using parameter-based transformations (such as grayscale adjustments, color space conversions, or selective pixel modification), it achieves encryption without generating excessive black pixels that cause printing blurs.
2Ease of operation
If whole blocks are reversed for encryption, then decryption can be performed, but images with multiple tones cannot be completely reproduced
Solution Approach 1:
The patent applies differential processing where only specific regions or blocks containing encryptable information undergo transformation. Blocks with multiple-tone images or photographs are either excluded from reversal or processed using methods that preserve tonal information, thereby maintaining reproduction accuracy while still providing encryption for text-based or binary content.
Solution Approach 2:
Instead of reversing the entire block including multi-tone areas, the patent inverts only the necessary portions (such as text regions) while preserving the original state of photographic or gradient areas. This selective inversion maintains the decryptability of text information while preventing degradation of multi-tone image quality.
3Reliability
If block positions are rearranged for encryption, then security is improved, but position detection accuracy decreases when image is degraded
Solution Approach 1:
The patent introduces reference marks or marker blocks with distinct, easily detectable characteristics at known positions within the rearranged blocks. These intermediary elements serve as anchors that facilitate accurate position detection even when the overall image structure is degraded or distorted, thereby maintaining both security through rearrangement and detectability through markers.
Solution Approach 2:
The patent uses distinct color patterns or contrast variations in specific marker regions to enable reliable position detection. By incorporating visually distinct features (such as high-contrast borders, specific color codes, or unique texture patterns) in marker blocks, the system can accurately identify block positions even under degradation conditions, while the rearrangement of these marked blocks maintains encryption security.
Data Source
AI summary
An image processing apparatus sections an image to be processed into a plurality of blocks, rearranges the blocks into positions specified by an encryption key that uniquely specifies the positions of the blocks in the image, determines a computing method used to convert pixel values of pixels that form a minimum area included in each of the blocks after the blocks are rearranged based on the pixel values of predetermined pixels that do not belong to the minimum area, and converts the pixel values based on the computing method.