With the technological advancements of the modern era, the easy availability of image editing tools has dramatically minimized the costs, expense, and expertise needed to exploit and perpetuate persuasive visual tampering. With the aid of reputable online platforms such as Facebook, Twitter, and Instagram, manipulated images are distributed worldwide. Users of online platforms may be unaware of the existence and spread of forged images. Such images have a significant impact on society and have the potential to mislead decision-making processes in areas like health care, sports, crime investigation, and so on. In addition, altered images can be used to propagate misleading information which interferes with democratic processes (e.g., elections and government legislation) and crisis situations (e.g., pandemics and natural disasters). Therefore, there is a pressing need for effective methods for the detection and identification of forgeries. Various techniques are currently employed for the identification and detection of these forgeries. Traditional techniques depend on handcrafted or shallow-learning features. In traditional techniques, selecting features from images can be a challenging task, as the researcher has to decide which features are important and which are not. Also, if the number of features to be extracted is quite large, feature extraction using these techniques can become time-consuming and tedious. Deep learning networks have recently shown remarkable performance in extracting complicated statistical characteristics from large input size data, and these techniques efficiently learn underlying hierarchical representations. However, the deep learning networks for handling these forgeries are expensive in terms of the high number of parameters, storage, and computational cost. This research work presents Mask R-CNN with MobileNet, a lightweight model, to detect and identify copy move and image splicing forgeries. We have performed a comparative analysis of the proposed work with ResNet-101 on seven different standard datasets. Our lightweight model outperforms on COVERAGE and MICCF2000 datasets for copy move and on COLUMBIA dataset for image splicing. This research work also provides a forged percentage score for a region in an image.
1. Introduction
Digital images are used in almost every domain, such as public health services, political blogs, social media platforms, judicial inquiries, education systems, armed forces, businesses, and so on. Rapid advances in digital technology have led to the creation and circulation of a vast amount of images over the last few years. With the use of image/photo editing tools like Canva, CorelDRAW, PicMonkey, PaintShop Pro, and many other applications, it has become very easy to manipulate images and videos. Such digitally altered images are a primary source for spreading misleading information, impacting individuals and society. The deliberate manipulation of reality through visual communication with the aim of causing harm, stress, and disruption is a significant risk to society, given the increasing pace at which information is shared through social media platforms such as Twitter, Quora, and Facebook. It becomes a significant challenge for such social media platforms to identify the authenticity of these images. For example, cybersecurity experts [1] have reported that hackers have the ability to access patient’s 3-D medical scans and can edit or delete images of cancerous cells. In a recent study, surgeons were misled by scans modified with AI software, possibly leading to a high risk of misdiagnosis and insurance fraud. In addition, manipulated images related to politics [2] distributed across social media platforms have the potential to mislead and influence public perceptions and decisions. For example, studies have shown that that particular types of images are likely to be reused and, in certain cases, exploited in online terrorism communication channels through media sources [3–5]. Image alteration becomes too easy using image editing software and even altering the original image in such a way that forensic investigators will not be able to identify the changes in the image. The major camera manufacturers use digital certificates to solve this issue. However, some companies have generated forged images taken from Canon and Nikon camera models. These fake images are passed through manufacturer verification software to perform their authenticity test [6].
Therefore, there is a need to develop a forgery detection technique that detects and identifies forgeries to resolve these challenges. Many forgery detection techniques shown in Figure 1 have been developed to authorize a digital image. These techniques are usually split into two types, referred to as active and passive detection techniques [7–9]. In active detection, a message digest or digital signature [10–14] is injected inside an image when it is created. In this forgery detection technique, statistical information such as mean, median, and mode is inserted into an image using some encryption method; this information is then retrieved from the image at the receiving side using a decryption method to check its authenticity [15]. In passive detection, changes in the entire image and local features are identified. It does not leave any visual clues of forgery, but it alters the statistical information of an image. It verifies the structure and content of an image to determine its validity.