The Reproduction of Color by Hunt

Can someone summarize the differences between the different editions? I think the sixth edition is current, but it is expensive. How does the sixth edition compare, for example, to the fifth edition?

I don’t know the book by Hunt, but I had the same problem when I was looking for the „Principle of Color Reproduction“ of J.A.C. Yule. But there are only two editions

At the end I decided for the old edition, assuming that most of the late additions concerns digital techniques. I can really recommend this book for everybody interested in color separation and masking techniques.