The Curves adjustment layer is one of the tools I use most often when editing photos in Photoshop. It is so powerful! You can add a new adjustment layer by clicking on the half black/half white circle icon at the bottom of the Layers palette and choosing “Curves.”
Here is what your Layers palette looks like:
And here is what the Curves dialog looks like, located in the Adjustments palette (if it’s not automatically showing, you can double click on your Curves layer and it should come up in the Adjustments palette):
The curves dialog shows the tones in your image – shadows, midtones, and highlights.
The X-Axis (at the bottom) represents the Input values, or the tones before any curves modifications have been made. Along the X-Axis, the left side of the dialog represents the shadows, the middle represents the midtones, and the right side represents the highlights in your image.
The Y-Axis represents the Output values, or the tones after the curves modification has been made. Along the Y-Axis, the bottom represents the shadows, the middle represents the midtones, and the top represents the highlights.
So what does all this mean, you ask?! If you pull the curve up, it will make your image brighter. Do this by clicking a point on the curve and moving it up and to the left. You may read the phrase “pull the midtones up” or “brighten the midtones” – below is what people are talking about when they say this!
If you pull the curve down, it will make your image darker.
On the curve, a value of ‘0’ represents pure black, and a value of ‘255’ represents pure white. So as you get closer to ‘0’ things will get darker. In contrast, the closer you get to 255, things will get brighter.
S-Curves and Contrast
S-curves are something I remember reading ALL about ALL over the place, and at first I had no idea what one was! It is simply a curve that looks like an ‘S,’ where the brighter tones are brightened and the darker tones are made darker. Here is an example of an S-curve:
The steeper the curve is, the more contrast there will be in your photo. You can see how much more contrast there is in the bottom photo using this specific s-curve:
These are the bare bones basics of Photoshop Curves, stay tuned for Part 2! As always, any feedback is much appreciated.