Blind Digital Image Forensics Technology Studies

With the development of computer technology, the use of photoshop can easily modify the pictures. However, everything has two sides. Many people began to fake photos. This makes people no longer trust in digital media. And Digital media's credibility has been seriously reduced. The effectiveness of digital photos has been lost. This leads inevitably lead to some problems, such as Image authenticity, image media, copyright, personal privacy protection. Digital image forensics technology has become a major issue in contemporary society.This paper discusses the basic framework for study of digital forensics based on image content. From the double-compressed JPEG tamper detection and identification of natural images and computer graphics in both directions in-depth study. The main thesis work includes the following aspects:(1) Reference to the calibration of compressed JPEG images: Propose a calibration image based on double JPEG compressed digital image tampering detection algorithm. After a double compression detection of tampering with the image after the image are to be removed on the left 4, When the compression again, this disrupted the original JPEG image of the DCT block. And again compressed JPEG images do not have the statistical properties of double-compressed.(2) The introduction of the concept ofΔE curve:ΔE is a distortion level of the rate of change in a series of compressed images and between the original images. The rate of change can more easily reflect the altered location of the image pairs of compression. The original image after JPEG compressionΔE pairs of relatively strong fluctuations in the mean curve. This is a clear sign of change inΔE of Background image.(3) Prediction error image based on the related to consistency of pixels of natural images and computer graphics of the identification: This increased the prediction error image. It can be extracted from the correlation of information. Prediction error image has greater generalization ability.Determine the color space: Through experiments HSV color space in the pixel feature extraction have better results.(4) Propose OC-SVM and MC-SVM combination with identifying the image type of thinking: Through experiments, the use of MC-SVM achieved good results.