In the age of chemical photography we could adjust the contrast of black and white prints, but there was virtually no practical way to adjust contrast in color images. They didn't make color print papers of varying contrast. (Dye transfer allowed for contrast adjustment, but that was pricey, rarefied stuff.)
Today, contrast is just a slider adjustment, although it isn't quite that simple: when you adjust for more contrast you may also get more saturation (see panel 8) which is often a problem. (You can always adjust back the saturation if you want more contrast without more saturation.)
Bottom Line: Contrast is a powerful processing tool that means as much in color as it does in black and white — it is just harder to manage in color.
85mm, f 1.2, 1/4000, ISO100
*I created these examples by adding levels and curves adjustment layers in Photoshop because my first tool, Lightroom, didn't let me take it to absurd levels.
Left
Right
Contrast reduced to the point of being a special effect. Looks like a foggy day.
Very low contrast image.
Reduced contrast. You might need to submit an image like this for print use if the printing process adds contrast, as is often the case.
Normal contrast, depending on your preference. Oddly, young people, who have much better eyes, prefer higher contrasts. Wonder why.
Slightly more contrast.
Lots more contrast and punch. An image normally gains a lot of contrast in printing, so to get this result in print you would submit a less contrasty image. But online, other than monitor variations, which are extreme and out of anyone's control, contrast should stay about where you set it.
Substantial contrast added.
The contrast is increased here without re-adjusting the saturation back down, so the skin tones are really over the top.
Contrast reduced to the point of being a special effect. Looks like a foggy day.
Very low contrast image.
Reduced contrast. You might need to submit an image like this for print use if the printing process adds contrast, as is often the case.
Normal contrast, depending on your preference. Oddly, young people, who have much better eyes, prefer higher contrasts. Wonder why.
Slightly more contrast.
Lots more contrast and punch. An image normally gains a lot of contrast in printing, so to get this result in print you would submit a less contrasty image. But online, other than monitor variations, which are extreme and out of anyone's control, contrast should stay about where you set it.
Substantial contrast added.
The contrast is increased here without re-adjusting the saturation back down, so the skin tones are really over the top.
