3D Effect

Anaglyph images are used to provide a stereoscopic 3D effect, when viewed with 2 color glasses (each lens a different color). Images are made up of two color layers, superimposed, but offset with respect to each other to produce a depth effect. Usually the main subject is in the center, while the foreground and background are shifted laterally in opposite directions. The picture contains two differently filtered colored images, one for each eye. When viewed through the "color coded" "anaglyph glasses", they reveal an integrated stereoscopic image. The visual cortex of the brain fuses this into perception of a three dimensional scene or composition.^*

For this assignment, you will combine two images into a single 3- dimensional image. These images will be viewed using red/blue glasses to give the 3D effect. With the red/blue glasses, one eye will only see the red channel, while the other eye will see the green/blue channel.

The two images will need to be pictures of the same thing taken from a slightly different viewpoint. The first image will view the object just to the left of the view of the second image. These two images will then be combined into a single, new image. At each pixel in this new image, the amount of red will come from the corresponding pixel in the left eye image, while the amount of green and blue will come from the corresponding pixel in the right eye image.

You will need to make sure that the two images have the same width and height before attempting to create the 3D image.

Examples

The following images were obtained from cameras on the Mars Exploration Rover. The image on the left represents what the left eye would see; the image on the right what the right eye would see. The image on the far right is the 3D image. You will need red/blue glasses to see the last image in 3D.

This next set of images is of a robot on a CS prof's desk, taken on a regular digital camera. In the first row, the image on the left is the left eye image and the image on the right is the right eye image. In the second row, the first image is the 3D image, and the second image is the 3D image obtained by converting the images to grayscale first. (Some sources have suggested that color information is lost when converting images to 3D in this manner, so the images may just as well be converted to black and white, first.) Again, you will need a pair of red/blue glasses to see the depth in the last two images.

This final set of pictures was obtained by taking a few pictures of the quad with a regular digital camera. Again, the left eye image is on the left, the right eye image is on the right, and two versions of the 3D image are in the second row.

Part 1: Obtaining Pictures

There are several possibilities for obtaining images to make into 3D images. In each possibility, there must be an image representing what the left eye would see, and another representing what the right eye would see. You may need to experiment with different possibilities to find something you like.

Possible methods for obtaining images include:

• Obtain stereographic images on the web (legally, not violating any copyright policies). The Mars Exploration Rover website
• Use Google Earth to capture images. Within Google Earth, find a view that you like (preferably one with 3D buildings), and capture it as an image. Then move the view just slightly and capture another image. How you change the view will dictate which is the left eye image and which is the right. (I found this to be a little tricky.)

• Take pictures yourself. To do this, pick a subject you find interesting. Inanimate objects with some texture or depth, within 10-15 feet of you, seem to work best. People don't make great choices in this situation because they have a tendency to move. Take one photo with your left eye looking through the view window. Then, without moving your head, slide the camera over just enough so that you can now take a picture with your right eye looking through the view window. It is really important to keep the camera level while doing this. Alternatively, you may try identifying something in your view to line the camera up with (some cameras have little boxes in the viewing window to help you with this). Take the picture, and then move the camera over a little bit (about the distance between your eyes), line up the camera in the same way, and take another picture. It may take a few attempts to get this right. If you want to try this and don't have a digital camera, check with one of your instructors.

Part 2: Extracting Red and Green/Blue

In order to create 3D images, we will extract the red from the left eye picture, and the green and blue from the right eye picture. We will then create a new image (the 3D image) which takes the red from the left eye picure, and the green and blue from the right eye picture.

1. Write a function that takes two pictures as parameters, one representing a left eye image, and one representing a right eye image. These pictures must have the exact same width and height. This function will create a new picture the same width and height as the originals. The pixels in this new picture will get their red values from the left eye image, and their blue and green values from the right eye image. The new picture should be returned at the end of the function.

2. (Optional, but check it out.) If you are working with color photos, you may find that it is easier to see them in 3D if you first convert them to grayscale. You may copy and use one of your grayscale functions from Lab 2 to do this.

3. Experiment with different images until you find something creatively pleasing. Save your 3D image as a new .png image. You can save it as a .jpg image, but the compression used with .jpg causes us to lose some color information related to the 3D perspective.
4. Create a web page for this programming project. Be sure to include a link to it from your course page. Post the original left and right images, and the corresponding 3D image on your web page for this project. (As a reminder, if you haven't been doing so, you should be including text on your web page to describe what it is these images are/what manipulations you have done to them.)
5. Be sure you have included appropriate documentation with your functions. Turn in a hard copy of your function(s), as well as the URL of your web page.