Success of modality translation methods expressed in terms of Fréchet Inception Distance (FID).

Smaller is better. Standard deviations are taken over the 3 folds for Zurich, Cytological and Radiological data. cyc, drit, p2p, star, comir denote the methods CycleGAN, DRIT++, pix2pix, StarGANv2, and CoMIR, respectively. Suffix _A (resp. _B) denotes generated Modality A (resp. B). The best result achieved by an I2I translation method on each of the datasets is bolded. FID values between the initial considered multimodal image datasets (B2A), as well as between the training and testing splits within each modality (A2A and B2B) for each dataset, are included as references. FID values between the generated CoMIR representations are not directly comparable to those of the I2I translations, since the method generates a different (artificial) modality. Comparison with the values for the original multimodal data (B2A) confirms considerable reduction of FID.