Digital BW, The Print

At the risk of prolonging the interminable argument that has
developed around this topic, I offer an illustration of how Austin's
concepts might have "real world" relevance.

Some years ago, before I retired, I worked with a medical 
illustrator and was required to make photographic copies of her 
beautifully rendered 'carbondust' drawings. The differences in 
the gray tones in these black and white works were so subtle 
that I was having difficulty, within the normal workflow of our busy 
photo lab, in capturing them precisely. After many frustrating 
attempts, I was finally able to explain my problem to her in terms 
she could understand and to request her cooperation.

I produced a print of a stepwedge on normal contrast photo 
paper and taped it to the edge of her drawing board. I explained 
that it would make my life easier if she would constrain the tones 
in her drawings to ones on the strip. Using a tone that fell 
between the steps would be difficult for me to copy exactly. Not 
knowing a terminology for these concepts, I referred to the 
difference between the darkest and the lightest tones as 
"external contrast" and the difference between adjacent tones as 
"internal contrast." The proverbial 'lightbulb' went on over her 
head and she said henceforth she would follow my suggestion.

Cephalis