Composite picture techniques: how to make convincing shadows

How do you create convincing shadows when making a composite picture of two images? Our quick tutorial shows you how to master these Photoshop effects.

Making a composite picture, the moment it begins to look right is when the shadows are added. Before this point, no matter how good the selection or mask is, it just doesn’t work.

We may not be aware of it, but our eyes are so accustomed to the ways in which light falls across objects and shapes, that any discrepancy is obvious. Since most of the time when making composite pictures you’re trying to create a believable visual trick, any problems with the light will stick out like a sore thumb.

So convincing shadows are very important, but before they can be added, the groundwork for making the whole effect convincing begins at the capture stage. We say this so often that it’s become a cliché, but no matter how good your Photoshop skills are, it counts for very little unless you know your way around a camera.

This is just as true for making composite pictures as it is for any other type of photography. If, like in the image here, you want to place any kind of object into a different scene, then the first thing to do is shoot each element under the same lighting conditions, at roughly the same angle, with similar depth of field and lens focal length.

Try using a couple of flash heads from a home photo studio kit when lighting elements for my composites. Attachments such as softboxes and reflectors change the hardness of the light, and of course, the appearance of the shadows.

If you don’t have a flash kit, then try a flashgun, or natural light from a window. The important thing is to use the light to add depth and drama to the scene, so never use on-camera flash.

Once you’ve shot your images and combined them with selections and masks, it’s time to add the shadows. Essentially, all you need to do to add a shadow to an image is darken part of it, and of course, there are lots of ways to do this in Photoshop.

The simplest way is often the most effective: just paint in black or dark grey, using a low brush opacity to build up the effect. Do this on a new layer, placed below the cut-out object in the layer stack.

Make sure the shadows adhere to direction, angle and hardness of light in the scene (if necessary, refer back to the original images for guidance). It’s a matter of judgement, so always paint on a separate layer so you can erase or soften the effect.

Another method photographers often use is to make a black shape the same as the cut-out, then transform it to make the shadow. Whichever method you choose to make the shadows, the most important thing is the judgement and skill you need to get it looking right. This is mainly down to your feel for the light.

How to make convincing shadows in your composite pictures

01 Fill with black
Use selections and layer masks to cut out the person and position her against the new background. Hold down Cmd/Ctrl and click the cut-out layer (or its mask) to load it as a selection. Make a new layer, then fill the selection with black. Drag the layer below the cut-out layer.

02 Skew the shadow
Press Cmd/Ctrl+T to enter transform mode, then hold down Cmd/Ctrl and drag the top middle point down to skew the shadow. Press Enter when the shape looks right. If the shadow meets an edge such as the books here, cut and paste a section of it to a new layer and transform again.

03 Fade it out
Merge the shadow to a single layer. Go to Filter>Blur>Field Blur. Set two pins to make the blur get stronger as the shadow gets further away from the cut-out figure. Next, change the Blend Mode to Multiply and lower the layer opacity slightly to help the shadow blend in.