cs.CVAug 27, 2026

Systematic Literature Review of Machine Learning Models and Applications for Text Recognition

Authors: Nuzhat Khan, Ab Al-Hadi Ab Rahman, Shahriyar Masud Rizvi, Ibrahim Yousef Alshareef, Muhammad Nadzir Marsono, Muhammad Paend Bakht, Mohd Shahrizal Rusli, Shahidatul Sadiah

Organizations: Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia · Department of Electrical and Electronic Engineering, American International University-Bangladesh, 408/1, Kuratoli 1229, Bangladesh · Department of Electrical Engineering, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta 87300, Pakistan · Faculty of Artificial Intelligence, Universiti Teknologi Malaysia, Kuala Lumpur 54100, Malaysia

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Abstract

Optical Character Recognition (OCR) for text recognition using machine vision has significantly improved, particularly when handling heterogeneous textual data. Traditional OCR models struggle with script variations, writing styles, and degraded documents. Advancements in technology are leading to new AI models with improved architecture for handling multiple languages and complex data formats. Despite this progress, a comprehensive evaluation of OCR advancements remains limited. Based on the established preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, this literature review presents an extensive assessment of OCR research to trace the evolution of AI models over the past decade. It explores the transition in AI models, application domains, data types, linguistic coverage, and challenges. Through a detailed analysis of 97 selected studies published during January 2015 - January 2025, key OCR models are identified, and their performance, strengths, and limitations are analyzed. The findings highlight how OCR technologies have evolved to address structured and unstructured text, scene text recognition, and multilingual processing. Unresolved challenges include limited resources for underrepresented languages, high variability in handwritten text, visual similarity among characters, and constraints in real-time OCR applications. To address these issues, several promising approaches are proposed. Key suggestions include self-supervised learning, multimodal AI, automated machine learning (AutoML), AI-assisted postprocessing, tiny machine learning (TinyML), and the creation of joint corpora for script matching. The future recommendations aim to enhance OCR accuracy and tackle the challenges identified for real-time industrial applications. This study will guide future research and establish a foundation for OCR field.

Figures & tables

Fig. 1: Example of end-to-end car plate OCR.
Fig. 2: Review protocol.
Criteria TypeDescription
PeriodFocus on recent advancements in OCR. Inclusion: Publications from January 2015 to January 2025. Exclusion: Articles published before 2015.
LanguageOnly English language articles are included. Exclusion: The articles published in languages other than English.
Type of literatureOnly high-quality, peer-reviewed sources are considered. Exclusion: Grey literature such as reports, government documents, working papers, and non-peer-reviewed sources.
Type of sourceOnly peer-reviewed journal and conference papers are included. Exclusion: Books, preprints, and non-peer-reviewed articles.
AccessibilityStudies must be accessible from major academic databases (IEEE Xplore, Scopus, Web of Science, SpringerLink, ScienceDirect, ACM Digital Library). Exclusion: Articles behind paywalls without institutional access.
Relevance to RQsArticles must contribute to at least two predefined research questions. Exclusion: Articles that do not address at least two research questions.
TABLE I: Inclusion and exclusion criteria
SourceInitial ResultsRetrieved Articles
Web of Science1923870
Scopus9039685
Google Scholar2110040
IEEE Xplore10149689
SpringerLink2480509
ScienceDirect312188
TABLE II: Studies retrieved from each database in automated search
Fig. 3: PRISMA flow diagram of reviewed literature.
Fig. 4: Database distribution of the final 97 retrieved articles after systematic screening.
Fig. 5: Classification of text types in OCR.
Fig. 6: Prominent AI models applied to Optical Character Recognition (OCR) over the past decade.
Fig. 7: Evolution of OCR models architectures in a decade.
Fig. 8: Popular OCR application domains. General domains (blue box) initially focused on document digitization (green box) and expanded to other domains (orange boxes).
Model TypeArchitectureDatasets UsedText Type / Language(s)Performance (Accuracy)Strength / Limitation
SVM [ 73 ] , [ 1 ] , [ 74 ] , [ 75 ] ,SVM-MLP-ETC, NCC, HOG-SVM286 Font Packs, Bangla Handwritten DatasetPrinted / Handwritten (English, Bangla)60.6% - 94.53%Works well for structured fonts but struggles with handwritten text and complex scripts
ANN [ 76 ] , [ 77 ] , [ 78 , 79 ]Feedforward NN, Backpropagation NN, Hopfield-ANNMNIST, CROHME, EMNIST, Picture Editor DatasetPrinted / Handwritten (English, Arabic)92% - 100%Effective in basic OCR but lacks generalization for large-scale real-world datasets
Neural Fuzzy System [ 80 , 81 ]IT2NFS-SPSA, ANFISAlphabetic and Numeric Datasets, Burmese OCRPrinted (English, Burmese)7.25% - 98.20%Reduces computational cost compared to traditional fuzzy systems but limited in scalability
CNN [ 82 , 83 , 84 , 50 , 31 , 85 ]VGG16, CRNN, Inception V3, ResNet50, Multi-CNNMJSynth, Kaggle, IAM, BanglaLekha-Isolated, CMATERdb, EMNISTPrinted/Handwritten (English, Arabic, Tamil, Bangla, Gujarati, Devanagari)57.2% - 99.76%Strong for printed OCR, but struggles with handwritten cursive text and script complexity
LSTM/BLSTM [ 51 ] , [ 14 ] , [ 86 ] , [ 87 ] , [ 88 ] , [ 89 ] , [ 90 ] , [ 91 ] , [ 92 ] , [ 93 ]Bi-LSTM, Gated-CNN-BLSTM, Tesseract LSTMMedical Records, EMNIST, IAM, BCSDLong-Sequenced Text (English, Arabic, German, Indonesian)91% - 99.94%Worked well for long-sequence text, but require high computational resources
Transformer [ 94 , 53 , 84 , 23 ]Vision Transformer (ViT), TrOCR, CharFormerShotor, Sadri, Born-Digital, LicenseNetMultilingual (Chinese, English, Persian)77.25% - 99.98%Outperforms CNNs/LSTMs in multilingual OCR, but computationally expensive
TABLE III: Reported accuracy of each OCR model on various datasets from selected studies
Fig. 9: Trends in language-specific OCR models.
Fig. 10: Sample of printed scripts: (a) Latin, (b) Devanagari, (c) Chinese, and (d) Arabic.
Fig. 11: A word cloud of keywords extracted from literature phrases describing challenges.
Fig. 12: Main sources of challenges in OCR.
Fig. 13: Key challenges and limitations in OCR.
Fig. 14: Data related challenges in OCR.
ModelApplicationChallenges ReportedReferences
CNNMultiple studies on various languages (e.g., Arabic, Bangla, Telugu, Tamil, Persian, Urdu, Gujarati, Devanagari, Javanese and Swedish)Small text size, blurry images, non-horizontal text, complex character shapes, compound characters, diacritics, connected characters, font variations, low-quality images, and overlapping text.[ 82 , 123 , 85 , 124 , 125 , 4 , 16 ]
DNNStudies on OCR for different languages and document typesHigh computational cost, large feature matrices, memory inefficiency, data imbalance, and difficulty in recognizing handwritten text.[ 126 , 17 , 127 ]
LSTMStudies on handwritten OCR, license plate recognition, and document processingSimilar character shapes, joint characters, varying orientations, illumination conditions, font and background variations, and computational resource limitations.[ 128 , 129 , 130 , 90 , 89 , 88 , 51 , 131 , 132 , 133 , 134 , 135 ]
SVMPrinted Arabic OCR and Bangla OCR studiesFeature extraction challenges, low contrast images, and difficulty handling multiple font types.[ 136 , 73 , 137 ]
ANNLanguage-oriented OCR implementations for Arabic, Persian, and Nepali scriptsImage quality issues, font variations, low resolution, and complex background interference.[ 138 , 77 , 139 , 140 , 141 , 142 ]
Hybrid Models (CNN + LSTM, SVM + MLP, etc.)Studies assessed ensemble approaches for OCROverfitting, increased training time, high memory requirements, and difficulty optimizing network layers.[ 84 , 125 , 96 , 143 , 54 , 23 , 144 , 145 ]
TABLE IV: Challenges associated with OCR models
Fig. 15: Frequently reported challenges, existing solutions, their limitations, and future directions to overcome these issues.
Fig. 16: Recent advancements in integrated systems for OCR.
Enhancement CapabilityBilateral FilterCLAHEOtsu ThresholdingGaussian BlurUnsharp MaskMorph. OpsWavelet Transf.GAN Methods
Noise Reduction✓✗✗◦✗✗✓✓
Contrast Enhancement✗✓✗◦✗✗✗✓
Resolution Enhancement✗✗✗✗✗✗✗✓
Blur Removal✗✗✗◦✓✗✗✓
Artifact Removal✗✗✗✗✗✗✗✓
Illumination Correction✗✓✗✗✗✗✗✓
TABLE V: Comparison of traditional image enhancement techniques and GAN-based methods. (✓= Supported, ✗= Not supported, ◦= Limited support)
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