Methods and Means of Identification of Computer Editing in Electronic Images of Documents

The article considers a number of theoretical and applied issues related to solving the task of computer editing identification in the process of forensic examination of electronic images of documents. The possibility of computer editing identification by means of digital image processing is demonstrated in specific examples including: a) methods based on correction and analysis of particular sections of the image tonal range (shadows, midtones and lightings) as well as the entire tonal range; b) methods based on the analysis of additional inside information (metadata) stored in files; c) methods of visual examination; d) methods of least significant bits analysis; e) methods based on some of the principles of the JPEG format (Error Level Analysis).The principles of operation and limitations of methods used to identify computer editing are given as well as the possibility of their application for working with PDF and JPEG files.There is also shown the study of possible use of methods to identify the signs of editing after an attempt to conceal them by adding noise and deliberately degrading the quality through repeated compression.The examples of specific software use (specialized programs, graphic editors) are described in relation to examination of electronic images of documents in particular expert situations.