Multiple Lighting Setup with Photoshop

Taking the 3 point light setup concept in 3D graphics and applying it in Photoshop

The 3 Point Light setup is a kind of "standard" setup that 3D artists use to render their still images of objects. It consists of the main light (key light), the rim light (backlight) and the ambient light (fill light). The ambient light sets the overall mood of the image. For example, a sunset image will have an orange ambience. This means that everything has a slight hue of orange. The key light is the main light source, for example the sun or a spotlight. The backlight is usually placed behind the object, opposite the key light, and is used to illuminate the object so that it pops out from the background. As a general rule of thumb, the key light and the backlight usually have opposite "temperatures". If the keylight is yellow (hot), the backlight is blue (cold) and vice versa.

3 point light setup reference

Applying it in Photoshop

For the purpose of this tutorial, lets start with an opaque sphere on a new layer.

Let's assume the light is from the top-left of the image. Use your Dodge Tool to give the sphere a specular highlight. I used "highlight" for Range and 20% for exposure.

To accentuate the light, let's burn in some dark shadow on the opposite side of the highlight on the sphere.

At this point, our key light is pretty neutral in temperature because we just did a highlight on the sphere without really changing its hue. Therefore, we shall also use a neutral backlight.

Note that there is a dark shadow on the opposite side, so we can't really use Colour Dodge on it. Instead, load a selection of the sphere by CTRL-clicking the sphere layer and create a new layer above it. Then, go to Select > Modify > Contract and type in 1 px. After that, use a soft, large brush and paint in a white stroke, like this:

Next, we have to paint in the shadow cast by the keylight. It should be below the object, obviously, and to the right (which is opposite the keylight).

CTRL-Click the sphere layer to load the selection once again and create a new layer beneath it. Then, press Q to enter Quick Mask mode, press CTRL+T to activate the transform gizmo (the bounding box with eight handlers on the sides and corners) and, while holding CTRL, drag the centre-top handler to the right, skewing the shadow in the process.

Adjust the shadow selection a little bit and press Enter to confirm your selection. Then, press Q again to exit Quick Mask mode. Now, fill in the selection with black for the shadow and give it a little Gaussian Blur (I used 0.9px).

Finally, for the ambient light. I created a layer on top of all the layers and filled it light blue because I wanted to simulate an open environment with a blue sky. Then, I set the ambient light layer's blending mode to Soft Light and dropped it's opacity to 50%.

And this wraps up our little tutorial on the 3 point light setup! Good luck trying this and remember to send your works, suggestions or questions to me! You may also want to download the .psd file I used in this tutorial for reference.