The DECIMER Image Transformer model was trained on data based on molecules obtained from PubChem . The entire molecules of PubChem were downloaded in SMILES format directly from the PubChem FTP site . To reduce the imbalance of data, all molecules with a molecular weight of more than 1500 Dalton were filtered out. All explicit hydrogen atoms were removed and stereochemistry was retained. SMILES strings with more than 152 tokens (see Tokenization) were filtered out due to their underrepresentation in the data (3,263 molecules). As a result, 108,541,884 molecules were selected in total. A diverse set of 250,000 molecules was selected to use as a test dataset from the whole dataset using the MaxMin 50 algorithm included in chemfp . Another million molecules were selected randomly and used for validation during the development, and the remainder was used as a training dataset (pubchem_1 see Supplementary Table ).