The review begins by grounding readers in the two great families of forensic techniques. Active methods embed protective information into an image before it ever leaves the camera or the editing suite. Digital watermarking is the classic example: a fragile watermark is woven into pixel data so that any subsequent alteration disturbs the embedded pattern and reveals the tampering. Watermarking has proven valuable in domains such as medical imaging, where authentication of every pixel is a legal and clinical necessity, and researchers have even developed lossless deep-learning-based watermarking schemes for that purpose. The weakness of active approaches, however, is structural. They require cooperation at the point of capture, and the overwhelming majority of images circulating online carry no such protection.

Passive, or blind, forensics asks the opposite question: what traces does manipulation itself leave behind? Every act of forgery, however careful, disturbs the statistical fabric of an image. Resampling introduces periodic correlations that betray scaling or rotation, a phenomenon first formalized by Popescu and Farid in 2005. JPEG compression leaves ghosts and block-grained artifacts that can be analyzed to localize edits. Camera characteristics such as chromatic aberration, sensor noise patterns, and camera response functions create internal consistency checks, because a spliced-in region often arrives with the fingerprint of a different device. Even the physics of light plays a role: inconsistent shading and shadows across a composite scene can expose a fabrication, an approach pioneered by Farid’s group and later extended into perceptual metrics for detecting retouching.

Within passive forensics, the review devotes particular attention to copy-move forgery, the deceptively simple act of copying a region of an image and pasting it elsewhere to conceal or duplicate content. Because the pasted patch comes from the same image, it inherits the same noise, lighting, and compression history, defeating many classic consistency checks. Early defenses relied on exhaustive block matching, notably Fridrich and colleagues’ 2003 block-based method, and on transform-domain tricks such as combining the discrete cosine transform with singular value decomposition. The field then shifted toward keypoint detectors: SIFT, SURF, ORB, KAZE, and Harris corners each offered distinctive, scale-tolerant descriptors that could be matched across an image to reveal duplicated regions, with clustering schemes such as J-Linkage and mDBSCAN used to separate genuine matches from coincidental ones.

Keypoint methods, however, struggle with small or extremely smooth tampered regions that yield too few distinctive features, and they can be defeated by geometric warping of the copied patch. This is where deep learning entered the picture. Convolutional neural networks learn manipulation traces directly from data, and architectures such as TamperNet, BusterNet, and Noiseprint demonstrated that networks could localize tampered areas, distinguish source from target regions in copy-move forgeries, and even recover camera-model fingerprints. Dual-branch CNNs, coarse-to-refined networks paired with adaptive clustering, and self-consistency learning, in which a network learns that spliced regions fail to cohere with their surroundings, all pushed accuracy upward. The review catalogs these architectures and compares their training regimes and performance across the field’s standard benchmarks: CASIA, MICC, GRIP, and CoMoFoD.

The most distinctive contribution of the survey is its focus on optimization, a layer of the pipeline that often goes unexamined in mainstream coverage. Deep networks are riddled with hyperparameters, from learning rates to layer configurations, and feature-matching pipelines involve thresholds and clustering parameters that are notoriously difficult to set by hand. Metaheuristic algorithms, nature-inspired search procedures such as particle swarm optimization, ant colony optimization, genetic algorithms, the multi-verse optimizer, the Archimedes optimization algorithm, and even more exotic entrants like the political optimizer and battle royale optimization, offer a way to tune these choices automatically. The review documents systems that pair CNNs with a hybrid spotted hyena and grasshopper optimizer, superpixel clustering refined by emperor penguin optimization, and golden ball optimization applied to medical image forensics, among many others.

The payoff for this hybridization is quantifiable. Across the studies surveyed, CNN-plus-optimization frameworks consistently outperform non-hybrid methods, reaching the 98 to 100 percent accuracy band on benchmark datasets. Optimization also improves robustness, helping detectors cope with post-forgery operations such as compression, noise addition, and blurring that would otherwise degrade matching. Yet the authors are candid about the limits. Robustness to geometrical distortions, rotations, scalings, and reflections remains a persistent weak point, since many detectors assume that copied regions appear in near-original form. Computational inefficiency is a second concern: some pipelines demand processing power incompatible with real-time or mobile deployment, a gap that lightweight architectures such as MobileNets and U-Net-style segmentation backbones are only beginning to close. Poor generalization across diverse forgery sources is the third weakness, as models trained on one dataset or manipulation type often falter on another.

Looking forward, the review identifies three research directions that could reshape the field. Transformer-based architectures, following the ViT and Swin Transformer lineage, are already being adapted for forgery localization, with recent work on multi-exit vision transformers suggesting gains in both robustness and efficiency. GAN-based detection is a double-edged frontier: generative adversarial networks can both synthesize deepfakes and be trained to recognize the artificial fingerprints that generators inadvertently leave behind, a question explored since researchers first asked whether GANs leave detectable traces. And real-time forensic systems, capable of operating across varied imaging conditions on everything from smartphones to newsroom verification desks, represent the practical destination toward which much of this research is pointing. Semi-supervised localization methods and meta-learning approaches that let models adapt quickly to new manipulation types also feature among the promising avenues.

What makes this survey timely is the asymmetry it highlights between the tools of deception and the tools of detection. Generative models improve at a pace set by commercial competition, while forensic systems must generalize to manipulations they have never seen, often under compression and resizing imposed by social media platforms. The authors’ synthesis suggests that neither raw deep learning nor clever optimization alone will win that race; it is the disciplined combination of the two, with metaheuristic search tuning learned models and learned models supplying the representational power that handcrafted features lack, that currently defines the state of the art. For journalists, courts, and platforms that increasingly depend on image provenance, the message is both reassuring and cautionary: near-perfect detection is now achievable in the laboratory, but translating that performance into robust, fast, universally trustworthy verification remains the field’s unfinished work.

Subject of Research: Image forgery detection using deep learning frameworks and metaheuristic optimization techniques

Article Title: Advancing image forgery detection: An investigation into optimization techniques and deep learning frameworks

Article References: R, A. M., J, D., & Kulkarni, R. N. (2026). Advancing image forgery detection: An investigation into optimization techniques and deep learning frameworks. Multimedia Tools and Applications, 85(9), Article 746. https://doi.org/10.1007/s11042-026-21916-0

Image Credits: AI Generated

DOI: 10.1007/s11042-026-21916-0

Keywords: image forgery detection, copy-move forgery, deep learning, CNN, metaheuristic optimization, particle swarm optimization, digital forensics, transformers, GAN, deepfake detection, CASIA dataset, benchmark datasets