Table 1 Summary of existing techniques in the literature.

From: A hybrid machine learning framework for offline signature verification using gray wolf optimization

Ref. No.

Authors

Proposed Technique

Advantages

22

Ojala et al.

LBP for texture classification.

Pioneering work on rotation-invariant texture classification.

24

Pal et al.

LBP and ULBP for Hindi/Bangla signatures.

Explored OSV for non-Latin scripts. Provided a baseline for LBP/ULBP performance.

25

Ferrer et al.

LBP and LDP for binary signatures.

Identified LDP as effective for black-and-white signature images.

27

Guerbai et al.

A variant of OC-SVM with combined distance metrics.

Addressed the small sample size problem common in real-world OSV.

28

Yilmaz et al.

Local Histogram features combining HOG and LBP per image region.

Used combined local features for a robust representation. Did not require skilled forgeries for training.

29

Serdouk et al.

Fusion of OC-LBP and LRFs.

Proposed a novel fused feature. Achieved a low AER reduction and reduced dataset size.

30

Kiani et al.

Radon Transform for feature extraction, classified with SVM.

Achieved a very low FRR of 2%.

31

Zulkarnain et al.

Triangulation geometric features with a Voting-based classifier.

Introduced a novel geometric feature set derived from the signature’s center of gravity.

32

Panchal et al.

Shape-based geometric features (area, eccentricity) with an ANN classifier.

Utilized simple, computationally inexpensive features.

33

Pandya

Hierarchical clustering technique for verification.

Employed a simple clustering approach.

34

Engin et al.

CNN model for noisy documents.

Achieved state-of-the-art accuracy on real-world noisy documents.

35

Bertolini et al.

Comparative analysis of LBP and LPQ for writer identification.

Direct comparison of texture descriptors for a related biometric task.

36

Singh et al.

Division of handwriting into texture blocks for LBP and CSLBCoP.

Detailed block-based analysis using advanced descriptors.

37

Bahram

Combination of MLBP and IWSL for writer identification.

Combined features to capture different aspects of writing style.

38

Fadaei et al.

LBP on sub-regions with feature optimization using PSO.

Used PSO for feature optimization.

39

Ahlawat et al.

Integration of LBP and a novel Octave Pattern for signature verification.

Enhanced both texture-based and structural signature characteristics.

40

Fadaei et al.

ScLBP for image retrieval.

Scale-invariant method validated on 7 diverse benchmark datasets.

57

Mashhadani et al.

Fusion of a Type-2 Neutrosophic Similarity Measure.

Directly addresses uncertainty, leading to higher accuracy and improved FAR/FRR over Type-1.

58

Abdulhussien et al.

Multi-feature fusion with GA-based selection and one-class learning.

Addresses Arabic script challenges and data imbalance. Validated on multiple datasets with a 5% improvement.