In this week’s free Deke’s Techniques video, Deke shows you how to blend the cast shadow of an object—-particularly a standard stock photo-type object against a white background—-into any new background. The trick is to use the Multiply blend mode to capture all the goodness of the shadow and mix it with its new environment, then put white pixels behind the actual object so that the opaque object itself doesn’t blend.
The technique works great for the volleyball that Deke uses in the movie, but I found myself wondering how it would work with say…a giant hunk of swiss cheese. 
Yes, I’m going to attempt to move my own cheese.
Although my object isn’t quite as easy to select as a nicely uniform round volleyball (which naturally lent itself to the ellipse tool), grabbing it with the Quick Selection tool actually worked fairly well. Rather than use a shape layer to provide the white backdrop, as Deke does in the video, I just filled my selection with white on a new layer between my cheese and my potential backgrounds.
Once the Cheese layer is set to the Multiply blend mode, the white pixels of the original background disappear and the shadow casts nicely onto my new tabletop scene. The Whiteness layer prevents the cheese itself from blending, as well. 
OK, Deke claims this will work on any background. Let’s see how it worked on the kitchen floor. (It’s so hard to keep white tile clean!)
Let’s see how it looks lakeside. Sure, the cheese looks a tiny bit radioactive, but look how well the shadow blends in. It’s actually still cheese-colored, now blending nicely with the wood of the dock.
Check out the video to see how it works, and then adapt to your own objects and backgrounds at will. And for members of lynda.com, Deke’s got an exclusive movie this week in which he shows you how to save your shadow against a transparent background, allowing you to use your object and its itinerant shadow in places that don’t support blend modes like Keynote, Power Point, and your friendly web presence.
If you’re not a member of lynda.com, you can get a free week’s trial at lynda.com/deke in order to check it (and the other 299 Deke’s Techniques) out.
Transform finished object
Deke,
Thanks as always for your very informative tutorials.
Have had no time to play around with this technique, but the “beach ball” ended up a bit LARGE for the beach composition.
Assume you grab both the circle and object layer above then you can transform them to put them in perspective (correct size) with your background.
Thank you Deke, also subscribe to Lynda(dot)Com and your training.
First port of call when I need to find out how to do something important and new.
Thank you
Russ
Great technique as always!
Great technique as always! Thank you. Just a hint: If you`re zoomed in very much and don`t know “where you are”, just use the birdseye view. I know you know it…
From a failed Email to info@deke.comi
Pardon the intrusion here but still relevant to the topic of your wonderful tutorials (maybe the new Dekeconstruction series?). I tried to Email this but I have a suggested challenge tut for you. So here goes.
Deke,
I am embedded in wheels - Flavor Wheels. They have a Beer Flavor Wheel (my business), A Coffee Wheel, a Wine Wheel a Chocolate Wheel etc.
Would it be possible for you to consider exploring how to do one in Illustrator or Photoshop - or in both? I kinda get it but the different segments of lines in different tiers causes me some issues. Looks like a lot of creating circles and lines and circles to cut lines and then create new lines and cut parts of those and so on ad infinitum. Take a look if you will at some wheels on line and you’ll see what I mean. In addition to such flavor wheels these are becoming popular ad tools and seminar slides segmenting topic into those Tony Buzan “Use your mind” type graphical memory tools. Can I encourage you to Use Deke’s Mind to do a tut on this? Infographics tools also here?
Cheers,
Gary.