Livre d'Or

Yes, ok, good point about the distinction between subtractive and additive colours. I know there used to be a device which was essentially a small digital camera you could point at, like, your sofa and bring it to the paint shop and they'd mix up a paint in a matching colour. But at some point you have to move from pigment colours to light colours, so if you want to be precise it makes sense that the standards are kept in physical, not digital form.