Image Decrypting Apparatus Adapting to Digital or Analog Media

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Solution Overview

Problem

Conventional techniques for encrypting and decrypting printed images suffer from degraded image quality due to ink smears and optical deformations, and security is compromised as the original image can be speculated from features of encrypted blocks.

Innovation Solution

An image decrypting apparatus that detects whether an encrypted image has passed through a digital or analog medium, selecting appropriate decryption processes to improve image quality and security by adding a determination flag or dummy signal, and using pixel value conversion and positioning markers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the encrypted image is decrypted using a reverse procedure of encryption, then the decryption process is simple, but the image quality is degraded due to ink smears and optical deformations

Engineering Contradiction:
Improvedecryption process complexityVSAvoidimage quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The decryption apparatus dynamically selects between two decryption processes based on the type of encrypted image input. For digital encrypted images, it applies the simple reverse encryption procedure. For analog encrypted images (scanned from printed media), it applies a sophisticated process that includes smear correction and feature amount extraction to restore image quality despite ink smears and optical deformations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the decryption approach based on the medium type parameter. When detecting that the encrypted image comes from an analog medium (printed and scanned), it activates parameter adjustment mechanisms including smear correction algorithms and feature amount extraction techniques to compensate for the degradation caused by printing and scanning processes.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the image is divided into blocks and rearranged for encryption, then the encryption process is efficient, but security is compromised as the original image can be speculated from block features

Engineering Contradiction:
Improveencryption efficiencyVSAvoidsecurity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention extracts critical feature information from the encrypted blocks before decryption. By extracting feature amounts that represent the essential characteristics of the original image, the system prevents unauthorized speculation of the original image from encrypted block features, while still allowing efficient decryption when the correct key is provided.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary feature extraction and analysis on the encrypted blocks before the actual decryption process. This preliminary action prepares the data in a way that maintains security by hiding original image characteristics, while enabling efficient and accurate decryption when the proper decryption key is applied.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2096858B1Image decrypting apparatus, image encrypting apparatus, and image decrypting method
Publication Date: 2019.01.09 FUJITSU LTD
  • EP2096858B1 patent drawingFigure 1~2
  • EP2096858B1 patent drawingFigure 3~5(B)
  • EP2096858B1 patent drawingFigure 6(A)~7(C)

AI summary

When a decrypting apparatus receives an encrypted image, the apparatus detects the state of the encrypted image and determines whether the encrypted image is an image passed through only a digital medium or an analog medium, according to the state of the encrypted image. When the encrypted image is determined to be the image passed through only the digital medium, the decrypting apparatus switches to perform a digital decryption process and, when the encrypted image is determined to be the image passed through the analog medium, the decrypting apparatus switches to perform an analog decryption process.