Toronto. By mid last century we had Kodachrome and its competition to give us good colour transparencies. They or the original subject could also be photographed on three monochrome negatives through colour filters to give one negative per narrow colour band. All three with filtering carefully stacked and aligned would give the full visible colour spectrum.
To create an accurate colour print, a very complex dye sublimate process (similar to the example of Technicolor shown in this video) was used. Each negative was projected or copied on a matrix sheet of thick gelatine to make a mould. After washing, the gelatine in the matrix varied inversely in depth with the intensity of the negative. Dye was rolled onto each matrix (subtractive dyes) and after careful registry on a special paper, the matrix back was carefully rolled and the dye was absorbed inversely proportional to the negative density. The process was repeated on the same sheet with careful registration for each of the three matrices using a different colour of dye (Cyan, Magenta, Yellow).
The Kodak Dye Transfer Process was one of many techniques that gave the most accurate colours available at the time. By mid last century, the colours were very high resolution and accurate. Check out the various books or articles on colour for more details.