Understanding Curves

In this tutorial, we'll be examining the power of the curves tool in photoshop and applying the things we learned to actual images. Curves is a powerful photoshop tool that can take the place of editing using levels, brightness and contrast, and hue and saturation. Don't get me wrong, curves should only be used on certain images or when one or more of the three elements are not needed to edit the image.

Step 1

Open up an image like this one:

(click me for high res)

Jeez... doesn't that look like a desktop background picture? Oh wait... it is! Anyhow, choose a picture that is - for the most part - bring and saturated like this one that we chose. Press control/command + M or you can click on the half black/half white circle otherwise known as a fill/adjustment layer and then select curves. You'll see something like this...

Think of this mathematically... the new color is the Y-axis and the original color is the X-axis on a Cartesian plane. If you notice the points at the top right hand and lower left hand corners, that means that the image is in a natural state. If, however, you move the upper right point to the uppermost left and the lower left to the lower right, black becomes white and white becomes black; otherwise known as an inverse or a negative.

notice how the black (upper left) is now white and the white (lower right) is now black.

Adobe automatically gives you presets such as color negative, color process, increase contrast, darker, lighter, etc... These presets and provide a solid foundation for creating your own presets in the curves panel. You can create/destroy presets by pressing the icon in the upper right hand corner:

Creating Contrast

The creation of contrast is very easy using the curves. It is the same general idea as using the levels panel to create contrast, that is, the whites become whiter and the darks become darker.

as you can see, there multiple anchor points, there are the two innate points at the corners and there are three more points. At the top there are two points which is basically telling photoshop to make the whites whiter and down below, it's telling photoshop to makes the darks darker. This is where knowledge of levels comes in handy... We can see the levels in the background, spanning from black to white. The actual levels would look like so:

There are similarities and differences in the two; however, we'll cover this later on... The same applies to the levels as with the curves. IF you were to drag the black pointer to the right using levels you're telling photoshop to make all of the ground that the pointer covers, black and vice versa with the white pointer.

A simple contrast curve would look like the inage above.

Darkening/Lightening Images

You can darken and lighten an image using the curves instead of using brightness/contrast or using the levels. A simple darkening curve would look like so:

A simple lightening curve would look like the image on the right hand side. As always, these are adjustable and you can create presets that can be saved and used later on.

We will work with the break down of colors in another tutorial!