Curves Basics

Curves Basics

Photoshop CS3 Tutorial


How to Adjust a Photoshop Image with Curves



Curves can be applied as a one time process or non-destructively as an Adjustment Layer. The purpose of curves is to re-map the values of the original image and assign them either lighter or darker values.

Curves can be applied to the entire image or adjusted one channel at a time (red, green or blue). To use curves on a channel, you would select the channel and choose Image > Adjustments > Curves.


Step One

Open an image in Photoshop (File > Open...).

Step Two

With the image layer selected, click the Create New Adjustment Layer icon in the Layers palette. Choose Curves... from the menu.

Step Three

The Vertical Scale represents the Output image luminosity values. The darker values are at the bottom and the lighter are at the top.

Step Four

The Horizontal Scale represents the original image luminosity values. The darker values are towards the left and the lighter are on the right.

Step Five

By default, the line is straight and the input and output values are identical. If you click in the center of the line and raise the curve slightly, the output image becomes lighter.

Step Six

If you take the same point you added in step five and lower it, the final image darkens.

Step Seven

A steeper curve adds more contrast to the image.

Destructive Curves

Using Adjustment Layers is considered a non-destructive workflow because you can always return to your original curve settings. You can also apply Curves to an image by choosing Image > Adjustments > Curves. Using this method doesn't give you the ability to return to the curves dialog box and edit the settings in the future.


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