Abstract

Due to the availability of powerful image-editing software and the growing amount of multimedia data that is transmitted via the Internet, integrity verifications and confidentiality of the data are becoming critical issues. However, currently, the accuracy of detecting and the recovery capability of the tampered images by the existing methods through watermarking strategy is still not at the required level, especially at a higher tampered rate. This paper proposes a new blind and fragile watermarking method to detect tampering and better recovery of tampered images. To improve the quality of both the watermarked and the recovered images, a new feature extraction scheme is introduced which will produce a short but comprehensive recovery code using a new compression strategy. If a block in the image tampers, the proposed embedded feature allows the original data to be extracted for recovery. To overcome tamper coincidence, every block’s watermarked data contains not only the recovery code belonging to the block itself but also its neighbor’s data as a second layer of recovery. Various size blocks were investigated to see the performance and compare their efficiency for recovering an image after different tampering rates. The test showed the smaller block sizes may be more suitable for locating tampering, where the bigger ones are more suitable when the tampering rate is higher. The bigger block sizes in the proposed method can recover an image even after a 60% tampering rate with high quality (more than 31 dB). The experimental results prove that the proposed method can have better efficiency for detecting tampering, and recovery of the original image, compared to the relevant existing methods.

Highlights

  • With the increased use of the Internet and the availability of signal processing technologies, integrity verification and protection of digitized information are becoming crucial issues

  • REVIEW A watermarking method was proposed by Lee and Lin [12] in order to discover the tampered areas in an image and recovery the original one

  • We know that one of the main challenges in image tamper detection and recovery is minimizing the implanted recovery code to gain a higher quality of watermarked image, while acquiring a good reconstruction of the tampered image

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Summary

Introduction

With the increased use of the Internet and the availability of signal processing technologies, integrity verification and protection of digitized information are becoming crucial issues. In Lee’s method, a tampered region is rebuilt from the data which are in all intact areas after the detection of modification This method cannot be applied when there is a large modified region because it affects the quality of the recovered image. Sing and Sing proposed a fragile watermarking method to detect modification in an image and recovery of the original one [16] They used Discrete Cosine Transformation (DCT) to produce recovery data. Other methods of recovery of a tampered image have been developed using DCT or Discrete Wavelet Transformation (DWT) in transform domains [8], [26], [31]–[33] These methods are very complex; they are limited when there is a need for real-time application. They were found to decrease the image quality [31]

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