The curves editor is a powerhouse for editing brightness and color tones. Some photographers will only use curves to make adjustments in post. This goes to show how flexible they can be. Regardless of the program, this tool can be intimidating to use. This is especially true if you don’t have a good grasp on how it works. This article isn’t an exhaustive depiction of what is possible with this tool–it’s a quick guide to help you become familiar with it.
Make it easy:
Here is something I wish that I had when I first started learning about curves–Exposure. Exposure’s curve controls are found on the Tone Curve panel. With the exception of the sliders, this tool behaves similarly to the curves editor in Photoshop. The sliders simplify the adjustment workflow. Changes to the sliders will display in the curve editor as a dotted line. This is a great way to visualize curve behavior. I recommend starting here.
In my recent Film Noir video tutorial. I used the controls in the Tone Curve panel to make the image more dark and mysterious, bring back some lost details, and make the photo appear to be lit by an old film projector. Adjustments like these are a simple process that produce great-looking results. Check it out.
How Curves work:
The curves editor essentially illustrates the relationship between the input and output tones of an image. Input being the unaltered image’s tone, output is the new value you assign to it. The tonal values are represented by the gradient strip at the bottom and side. The curves themselves provide a way for you to selectively manipulate these tonal values. An alteration made to a given input tone such as the midtones, will correlate to a change in the image’s brightness. Below is a curve example for darkening.