The advanced shadow- step-by-step

The following step by step creates a very realistic cast shadow, and is particularly useful when compositing within a photograph.

1. Silhouette the object to be placed- Using paths, Quickmask, or any necessary combination of selection tools, create a believable silhouette of the object. Once silhouetted, isolate the object to its own layer.
   
   
2. Create the drop shadow- On a new layer, create a selection for the drop shadow. I sometimes use paths, and at other times I just freehand it until things look believable. There is no set way to do this, it varies from object to object. Once the selection is created save it so that it can be accessed later if necessary.
   
   
3. Feather the selection- softening the edges for the shadow.
   
   
4. Fill the selection- At this point, you have the option of filling the selection with color, or with the underlying image. If you're compositing into a photo, its a good idea to modify a copy of the underlying image. Capturing the underlying image is as simple as crafting your selection as described in step 3, selecting the image layer, copying the data and pasting it into its own separate layer. With this approach you can create a convincing shadow without altering the actual background image.
   From there, try using curves to darken the shadow. Then use the Dodge and Burn tools to make the shadow deeper as it gets close to the object, and lighter as it moves away.
   If you fill with color be sure you do not use a pure black, try to use dark colors instead. Lighten the opacity, and try the Blending modes such as Overlay and Multiply to integrate the shadow into the background.
   
   
5. Shadow Tweaks - Select the Sharpen and Blur tools and modify the shadow edges, making them tighter as they draw near to the object and softer as they recede. Use color tools to add a slight tint to the shadow. Another advanced tip is to add reflected light. If the object is a bright color, like a bright red ball or an orange, brush in a slight color cast to the ground within the shadow. Do this lightly, it should be a subtle effect.
   
   
6. Object Tweaks- To complete the photographic effect, the object itself is darkened and blurred, using a combination of the sharpen/blur and dodge/burn tools. In addition to adding shadow areas, the airbrush was used as a final touch to add some blue reflected light and to darken things down further.