Drop Shadows and Other Effects
Creating a "drop shadow" behind a silhouetted object scan is a very effective way of creating a sense of depth and making a scanned object look as though it's actually sitting on a surface. In the 1996 edition of this book we described a series of steps for creating these soft, blurred shadows. The process is much easier now that drop shadows have been automated in Photoshop, through the Layer Effects submenu. This submenu also makes it possible to create outer glows, inner glows, pillow embossing and other effects. Other image-editing programs include similar functions.
Before applying a drop shadow though, it's important to make sure that the object to be shadowed has been carefully silhouetted so that none of the background color remains along its edges. Otherwise there will be a thin line of color between the object and the drop shadow. One easy way to do this in Photoshop is to use the wand tool to select the white area around the object and then choose Expand from the Selection menu to enlarge the selection area by 1 or 2 pixels. This should select whatever stray pixels of color may remain along the object's edges, which you can then delete.
Automating shadows and effects
We started by scanning a pair of scissors (A) and used Photoshop's lasso tool to select the background and delete it. We then adjusted the contrast and color saturation of the red plastic handle and metal blades (B). We created a layer below the scissors, filled it with solid white and used the Layer Effects submenu to apply effects to the layer containing the scissors, including Drop Shadow (C), Inner Glow (D), Outer Glow (E), and Pillow Emboss (F). We chose black as the color for all of these shadows and effects and all were cast onto the white background layer.
Casting shadows on color
However, an object with a shadow can also be placed in a layer above one that contains a multicolored image and the shadows will appear to be cast onto that image, as happened when we placed our drop-shadowed scissors over a scan of origami papers (G).