Apr 27 2009
Turn 2-D images into 3-D masterpieces!!
(from Episode #76 of The Lab with Leo Laporte)
Have you ever seen one of those movies or a still image that appeared to be in 3-D when you wore special red and blue glasses? It’s easier than you think to make one of those images. In fact, I’ll show you 2 methods to achieve this effect. The first one requires you to take two pictures of a stationary subject and merge them in Photoshop. The other will take an existing photo and convert it to 3-D.
First, I should explain how 3-D images work. We view the world in 3 dimensions because our two eyes see things slightly differently and our brain interprets the two pictures our eyes see as being 3 dimensional. We unconsciously calculate depth, width and height based on the similarities and the differences between those two pictures. It just happens. We don’t even realize we do it.
These artificial 3-D images we’ll be creating, called anaglyphs, simulate in a 2-D image the 2 pictures our eyes see when we look at actual 3-D objects. The red and blue lenses of the 3-D classes block out certain information in the 2-D image allowing the blue lens only see the red channel of the image and the red lens to only see the blue and green channels. This allows a single 2-D image to hold the 2 slightly different images our eyes need to see in order to perceive 3-D information.
Here are a few methods you can can use to make one of these images:
The 2 picture/1 camera method (this method works on stationary objects)
With a digital camera affixed to a sturdy tripod, take a picture of the stationary subject. Carefully move the camera and tripod 2.5 and 3 inches to the right and take another picture.
What you have effectively done is taken a left eye image and a right eye image.
Open both images in Photoshop. Using your first image (your “left eye” image) open the Channels palette and click the Red channel (Ctrl-1 on PC or Command-1 on Mac). Select all (Ctrl-A on PC or Command-A on Mac) and copy (Ctrl-C on PC or Command-C on Mac).
Now go to the second image (your “right eye” image) and click the Red channel (Ctrl-1 on PC or Command-1 on Mac) in the Channels palette. Paste the Red channel from the “left eye” image in Red channel of the “right eye” image (Ctrl-V on PC or Command-V on Mac).
Click the RGB composite channel in the Channels palette (Ctrl-~ on PC or Command-~ on Mac) and put on your 3-D glasses (make sure the left lens is red and the right lens is blue).
The 2-D to 3-D conversion method
The problem with the 2 picture/1 camera method is that you can’t capture action. No pictures of your dog jumping to catch a frisbee. No 3-D pictures from the airshow. None of that.
The 2-D to 3-D conversion method allows you to alter an existing 2-D image and make it 3-D.
I’m going to start with this image of Dr. Tiki and Leo on the set of The Lab…
What you need to do is select the frontmost item in the photo and save the selection as a channel. Then select the next most foreword item and save that as a channel and so on and so on until you reach the background. How detailed you want to be is up to you. I have selected Dr. Tiki’s face, then his body, then Leo’s arms and camera, then Leo, then the column behind Leo and then I left everything else as the background. Here’s what my Channels palette looks like:
Now, create yet another new empty channel and fill it with white. In your Swatches palette, select 20% Gray, load the back-most item in the Channels palette as a selection (in my case, “Alpha 5″ in the screenshot above) and then fill the selection with 20% Gray in the new channel. Continue to select progressively darker shades of gray and use the color to fill the selections of each increasingly more foreground channel in our new channel. So, for my image, I’ll make a selection of Alpha 4 and fill with 40% Gray, then make a selection of Alpha 3 and fill that with 60% Gray, then Alpha 2 with 80% Gray and Alpha 1 with Black. Plan out your selections and grays so that you can make a smooth progression from the background in White to the foreground in Black. Here’s what my channel looks like:
I know it looks scary–bear with me.
Go Filter>Blur>Gaussian Blur… and use a setting of 10. Click OK. This with blend the levels a bit. Now we need to expand the coverage of the different levels of depth a bit. To do this we will use a Filter called Minimum which shrinks the coverage of the lighter areas of the affected image.
Go Filter>Other>Minimum… and plug in a value of 10. Click OK.
Select All (Ctrl-A on PC or Command-A on Mac) and Copy (Ctrl-C on PC or Command-C on Mac). Create a new Photoshop document and Photoshop will automatically plug in the height and width of the image held in the clipboard’s memory, so you need only click OK.
Paste the funky channel in the new document (Ctrl-V on PC or Command-V on Mac) and save this new document as a Photoshop (.psd) file and save it somewhere where you will easily find it again. Close this new file and direct your attention back to the main document.
Click the Red channel in the Channels palette (Ctrl-1 on PC or Command-1 on Mac) and activate the “eye” icon next to the RGB composite channel in the channels palette (just activate the “eye” don’t select the RGB composite channel itself). It should look like this:
You should see the full color image in the document window but what you’re about to do will only affect the Red channel.
Go Filter>Distort>Displace… and enter 20 in the Horizontal Scale field and 0 in the Vertical Scale field and click OK.
And that’s it! It’s in THREEEEEEEEEEEEE-DEEEEEEEEEE!!!
Still need more 3-D stimulation?
Check these anaglyphs on Flickr.
Do you just need to buy some 3-D glasses? I bought mine here.
