Overuse of the word 'Contrast'.

[Jay DeFehr]

Hi Darin. I understand your frustration and confusion. Contrast is central to photographic imaging, and a clear understanding of the concept is critical. I intend to make a little animation sequence that will illustrate the concept, but haven't gotten around to it yet. Most photographers that I know are very visual people and respond to visual demonstrations, but I think you can follow in your imagination. Imagine a bar divided into three equal sections; pure white on the left, middle gray in the middle and pure black on the right. This is a very high contrast scale. Now imagine that you can tug at each end of this scale and stretch it, but as you do so, new tones averaged between the two adjacent to them appear. The longer you stretch the scale, the smaller the tonal difference from one tone to its adjacent tones, and the more of them. So a long scale has many steps between white and black, while a short scale has few. I hope I haven't added to your confusion.

[Noshir Patel]

Ok, I'm curious.

Give me a definition of contrast that doesn't have to do with the difference between a lighter value and a darker value (with larger differences referred to as higher contrast).

Sure, high contrast film (that is film that renders a medium contrast scene as a high contrast transparency) is bad for a high contrast scene. It makes sense. One magnifies the other producing a very high contrast transparency (where the supposed ideal is a medium contrast transparency).

Even lens contrast makes sense with this definition. A lens with less flare or whatever will produce a more pure (and thus higher contrast) image than one with more flare (I am using the term flare loosely... not sure if it's quite correct usage). The flare adds light to darker areas in the resulting image, thus lowering contrast (I suppose it subtracts a bit of light from the light areas as well).

Guess I don't see the inconsistency (or I've had the good fortune not to come across people who use the term in a very confusing way).

I suppose if someone used the term high contrast to mean high dynamic range, that would be confusing, but in my mind that usage is simply wrong (possibly even backwards).

[Tito Sobrinho.]

Contrast to me means, rich blacks with detail as well as rich whites with detail and a myriad of grays in between.

[Kaatharine Thayer]

>Contrast to me means, rich blacks with detail as well as rich whites with >>detail and a myriad of grays in between.

Given that definition, is there any distinction in your mind between "contrast" and tonal range? What would you call a print that had only black tones against white paper?

[Tito Sobrinho.]

I called a bad print due to bad exposure and or development . Not to be confused with a Low Key picture that has Zones I, II, III and V. My prints have rich blacks with detail as well as rich whites with detail. I called - excellent local contrast. Called it tonal range if you will.

[Rob Tucher]

Ralph, good point. To me, and gotten from George Tice years and years ago in a printing workshop, more separation is rendition of more shades of gray between black and white. So a print with low separation (high contrast) has black, white, and a limited number of gray tones between them, with a more precipitous jump from one gray to the next. A print with a high degree of separation would have a very large number of decipherable gray tone between black and white and this would appear lower in contrast...because you can see multiple grays inside, let's say, an area that might block up as black only if printed at a higher contrast. It at first seemed counter-intuitive to me but now makes complete sense.

[Kaatharine Thayer]

I think this is an important issue, but my concern isn't that the word is used in different contexts; I'm more concerned about the fact that even if we stick to one context, say print contrast, we don't seem to have a universally agreed-upon language, as is evident from the above discussion.

This lack of clarity over "contrast" has got in the way again and again when I've been trying to help novice gum printers trouble-shoot problems they have with their process; the difference between how we use the word often obstructs my ability to "see," without having the print in front of me, what's actually going on.

Two cases in point: one beginning printer kept insisting that a certain condition resulted in a "high contrast" print. This didn't make sense to me, and after a few followup questions it became clear that what she really meant was that the print was all black; there were no other tones-- no midtones, no highlights, no details in the shadows, all black. Within a couple of weeks of that encounter, another inexperienced gum printer said that a different condition caused her to get a "low contrast" print; again her statement didn't jive with my experience, and finally it came out that what she meant by "low contrast" was the same thing the first student meant by "high contrast": a totally overexposed print with no tonal range, just one dark value across the entire print.

I suspect that the first printer defines "contrast" in terms of DMax: how dark is the darkest dark, regardless of whether there are any other tones in the print. And the second person probably defines "contrast" in terms of tonal range in the same way it's been defined by some in this discussion: if contrast means a long tonal range, just one tone must mean low contrast. For myself, I don't think that the word "contrast" one way or the other has any useful application in a situation where all the tones are blocked and the obvious problem is overexposure. But given these and other confusing discussions, I too have been puzzling about the word "contrast" and the various ways it is used and misused.

When I asked my earlier question, I was wondering how Tito would characterize Harry Callahan's photographs of weeds, say, in terms of contrast.

[Noshir Patel]

Katharine,

It seems to me that a "high contrast print" would be one where the difference between a particular light area and a particular dark area is greater than a "normal contrast print" (whatever that is... clearly terms like "high" have to be relative to something).

A totally black print is certainly not a high contrast print. It is an extremely low contrast print. So, I'd say your analysis of the first printer's terminology is probably correct... a complete misuse of the word "contrast". Of course, at this point the error in printing is probably such that the idea of contrast should be left out of the discussion.

As for high contrast as it relates to tonal range...

In general a higher contrast print would have a longer tonal range compared to a lower contrast print (so long as the entire tonal range capability of the paper is not used by both prints). At the extreme (where both prints are using the entire tonal range the paper is capable of) tonal range would be identical, but the higher contrast print would have a greater difference between two given gray points on the print. There would also likely be more pure white, pure black, or both.

[Kaatharine Thayer]

While it's true that an all-black print has no contrast, therefore technically could be called a "low contrast" print, I still say that the word "contrast" has no useful application in that situation and bringing it in just confuses the issue.

I'm on the same wavelength with Jay about contrast, and with the people who defined contrast in terms of slope. My point, which may have been stated so subtly as to be missed entirely, was that people talk about print contrast in ways that contradict each other, rather than there being a universally agreed-upon way to define contrast. This discussion continues to prove my point, and I'll rest my case and move on.

[Dan Fromm]

This discussion makes me feel like I'm back in a junior high school english class. Compare and contrast common language interpretations of, yes, contrast.

Cheers,

Dan