I am sure whatever I saw but not a proof at hand at this moment.
I think We can reverse engineer the situation. What is the meaning of flat histogram , what kind of a image have a flat histogram. I am an Crossfield 656 Drum Scanner operator , have been printed 100 000 color negatives and been a service man for Heidelberg Newspaper machines , used many Leitz products and a thinker on classical paintings and the Leica relation for 15 years.