Contrast confusion

If you have a properly exposed image, does adding contrast cause more lost highlights? So I guess what Im saying is, if I set my black point and exposure so that I have the highlights exactly where I want them, why would I ever want to use the contrast slider?

Well, to me Contrast is a matter of taste that pertains to the individual image. I tweak to get a pleasing look, not just the proper Whites and Blacks.

Doesnt that give you lots of blown out areas? It seems that even a slight contrast boost of 2 or 4 triples the amount of red highlight warnings.

JakAHearts wrote in post #12353665
If you have a properly exposed image, does adding contrast cause more lost highlights? So I guess what Im saying is, if I set my black point and exposure so that I have the highlights exactly where I want them, why would I ever want to use the contrast slider?

There's a technique where in LR or ACR, instead of adjusting the Blacks slider, briefly go into the Tone curve tab and adjust the Shadow and Dark sliders. This will preserve your highlights.

http://www.retouchpro.​com …etouchPro_Maxim​um_raw.pdf

Thanks Chas. Ill check it out.

An S-shaped curve increases contrast without affecting the white and black points so long as the ends of the curve are not moved.

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1. Why?
Because setting the black and white points right doesn't guarantee the necessary overall crispness, especially when dealing with lots of midtones.


2. How?
Not by the use of the Contrast slider, as that may indeed produce blocked shadows and/or clipped highlights. The easyest (and tone-wise locally adaptive) is the use of the S-curve, as Elie showed above. Another solution is Local Contrast Enhancement that some programs offer with the Clarity slider. If you don't have the latter, you can do it with Unsharp Mask, by setting the parameters to about:

Amount 15-20
Radius 50
Threshold 0.

tzalman wrote in post #12354310
An S-shaped curve increases contrast without affecting the white and black points so long as the ends of the curve are not moved.

+1

Use curves for contrast adjustment and nothing will get blown. Learn how to use em and forget about contrast slider forever.

Overall contrast reduced and replaced with local contrast:

frenchconnector wrote in post #12354745
+1

Use curves for contrast adjustment and nothing will get blown. Learn how to use em and forget about contrast slider forever.

Thanks! This seems like what Ive been doing. I still get good contrast in my edits. I just didnt understand why the contrast slider was even there.

Contrast slider in LR3 changes midtone contrast. Same for the contrast slider in ACR and Photoshop CS4 and later. These will not (hardly) affect clipping.
It's the "Legacy" contrast slider in Photoshop that sucks.