Optical Chemical Structure Recognition
Handwritten chemical structure recognition with RCGD and SSML

Handwritten Chemical Structure Recognition with RCGD

Proposes a Random Conditional Guided Decoder (RCGD) and a Structure-Specific Markup Language (SSML) to handle the ambiguity and complexity of handwritten chemical structure recognition, validated on a new benchmark dataset (EDU-CHEMC) with 50,000 handwritten images.

Optical Chemical Structure Recognition
Chemical structure diagram representing the ICMDT molecular translation system

ICMDT: Automated Chemical Structure Image Recognition

This paper introduces ICMDT, a Transformer-based architecture for molecular translation (image-to-InChI). By enhancing the TNT block to fuse pixel, small patch, and large patch embeddings, the model achieves superior accuracy on the Bristol-Myers Squibb dataset compared to CNN-RNN and standard Transformer baselines.

Optical Chemical Structure Recognition
Diagram showing a pixelated chemical image passing through a multi-layer encoder to produce a molecular graph with nodes and edges.

Image-to-Graph Transformers for Chemical Structures

This paper proposes an end-to-end deep learning architecture that translates chemical images directly into molecular graphs using a ResNet-Transformer encoder and a graph-aware decoder. It addresses the limitations of SMILES-based approaches by effectively handling non-atomic symbols (abbreviations) and varying drawing styles found in scientific literature.

Optical Chemical Structure Recognition
4-tert-butylphenol molecular structure diagram for Image2SMILES OCSR

Image2SMILES: Transformer OCSR with Synthetic Data Pipeline

A Transformer-based system for optical chemical structure recognition introducing a comprehensive data generation pipeline (FG-SMILES, Markush structures, visual contamination) achieving 79% accuracy on real-world images, outperforming rule-based systems like OSRA.

Optical Chemical Structure Recognition
Bromobenzene molecular structure diagram for MICER OCSR

MICER: Molecular Image Captioning with Transfer Learning

MICER treats optical chemical structure recognition as an image captioning task, using transfer learning with a fine-tuned ResNet encoder and attention-based LSTM decoder to convert molecular images into SMILES strings, reaching 97.54% sequence accuracy on synthetic data and 82.33% on real-world images.

Optical Chemical Structure Recognition
Patch-based classification pipeline showing overlapping green and blue grids over a chemical image with Markush indicators highlighted in red.

One Strike, You're Out: Detecting Markush Structures

Proposes a patch-based image processing pipeline using Inception V3 to filter Markush structures from chemical documents, outperforming traditional fixed-feature (ORB) methods on low-SNR images.

Optical Chemical Structure Recognition
4-chlorofluorobenzene molecular structure diagram for SwinOCSR

SwinOCSR: End-to-End Chemical OCR with Swin Transformers

Proposes an end-to-end architecture replacing standard CNN backbones with Swin Transformer to capture global image context. Introduces Multi-label Focal Loss to handle severe token imbalance in chemical datasets.

Optical Chemical Structure Recognition
ChemGrapher pipeline overview showing segmentation and classification stages

ChemGrapher: Deep Learning for Chemical Graph OCSR

ChemGrapher replaces rule-based chemical OCR with a deep learning pipeline using semantic segmentation to identify atom and bond candidates, followed by specialized classification networks to resolve stereochemistry and bond multiplicity, reducing error rates compared to OSRA across all tested styles.

Optical Chemical Structure Recognition
Encoder-decoder architecture translating a chemical structure bitmap into a SMILES string

DECIMER: Deep Learning for Chemical Image Recognition

DECIMER adapts the “Show, Attend and Tell” image captioning architecture to translate chemical structure images into SMILES strings. By leveraging massive synthetic datasets generated from PubChem, it demonstrates that deep learning can perform optical chemical recognition without complex, hand-engineered rule systems.

Optical Chemical Structure Recognition
Thymol molecular structure diagram for Staker deep learning OCSR

Deep Learning for Molecular Structure Extraction (2019)

This paper presents a two-stage deep learning pipeline to extract chemical structures from documents and convert them to SMILES strings. By training on large-scale synthetic data, the method overcomes the brittleness of rule-based systems and demonstrates high accuracy even on low-resolution and noisy input images.

Optical Chemical Structure Recognition
Handwritten chemical ring recognition neural network architecture

Handwritten Chemical Ring Recognition with Neural Networks

Proposes a specialized Classifier-Recognizer architecture that first categorizes rings by heteroatom (S, N, O) and then identifies the specific ring using optimized grid inputs.

Optical Chemical Structure Recognition

Handwritten Chemical Symbol Recognition Using SVMs

A 2013 paper introducing a hybrid recognition system for handwritten chemical symbols on touch devices. Combines Support Vector Machines (SVM) for classification with elastic matching for geometric verification, achieving 89.7% top-1 accuracy on pen-based input for chemical structure drawing applications.