• Photonic synapse capable of multispectral color discrimination is demonstrated.
• Strong excited-state dipoles enable remarkable discrimination intensity (0.05–40 mW cm-2).
• This approach is not restricted to a specific medium in the channel layer, and convolutional neural network with synapses array achieves over 94% inference accuracy for Canadian-Institute-For-Advanced-Research-10 images.
• The proposed approach offers a promising solution for achieving robust and versatile RGB color discrimination in photonic synapses, enabling significant advancements in artificial visual systems.