How the Tone Curve Works in Photoshop

Photography Tips

If you’ve spent much time post processing your photographs, you’ve come across the tone curve. Found in a number of the most widely used editing programs, it can be used to control brightness, contrast, and color channels precisely. But do you know how the tone curve actually works? Everything you’ll ever need to know is provided in this short yet informative clip:

Though the tone curve is not limited to Adobe products, Photoshop provides users with control over tonality more so than any other similar software, making it a great place to experiment and explore the tool’s capabilities.

As the channel shows, the tone curve can be easily accessed for quick fixes through Photoshop’s Adjustments panel. The curve property panel itself is rather straightforward, featuring a straight diagonal line along a line graph. Users can add points to the line and then proceed to manipulate the shape of the line, which in turn makes changes to the image’s corresponding tones.

Along both sides of the graph, you’ll notice gradient bars running along the the bottom and side of the panel. The bottom variable represents a tone that already exists within the image. When moving a point within the diagonal line, you’re commanding the bottom variable value to equal a new tonal variable represented in the side bar gradient. For instance, if you created an S curve within the line graph, you’d be upping the overall contrast of an image. This is because you’re ordering the program to make the darker grey tones within the image closer to black and the lighter grey tones closer to white.

The individual red, green, and blue color channels within an image can be adjusted through the tone curve as well. With this method, it’s possible to accurately color correct or create filters and tints to enhance the quality of your photograph. By combining adjustments made in individual channels, you can create new overall adjustments. This tutorial demonstrates how it’s possible to tint a photograph purple by performing identical adjustments on both the red and blue channels.

Because of its impact on image tonality, the tone curve is considered one of the most powerful tools out there. And with just a little bit of practice, it’s easy to get a feel for what you need to do to customize the highlights, shadows, and colors in every one of your photographs.