Basics – 3D depth perception
Before we start, first a simplified version of the basics of depth perception (see also: How 3D Movies Work).
As a human we have (usually) 2 eyes, which each look at objects under a slightly different angle. The illustration below gives a simplistic representation of this where a left eye and a right eye try to observe objects A and B.
The left eye does not see object A, only object B, whereas the right eye sees both object A and B.
Our brain, if functional, combines these two pictures and perceives depth … which we will use as the basics for creating a 3D picture.
Tip : For those who’d like to dig deeper in the matter, there are numerous clubs world-wide dedicated to 3D StereoPhotography, find an overview here sorted by country. For example the Nederlandse Vereniging voor Stereofotografie.
3D View – Left versus right eye
How to create your own 3D pictures
To mimic the use of 2 eyes, we will need 2 pictures under a slightly different angle.
To do this “perfect” you’d need 2 identical camera’s on some sorts of mount so we can take the same picture at exactly the same time or have a camera capable of taking 2 pictures at the same time (more and more cameras offer this option).
Most of us however do not have a 3D capable camera available or 2 identical camera’s for that matter, so we will try to do this with only one camera. Using one camera works best with objects that do not move.
We will use this for both “Red and Blue Glasses” and 3D TV, for which we can use exactly the same pictures.
Taking the right pictures
So we first need to take the 2 pictures of an object we have chosen – this can be anything. Again: best results can be had with objects that do not move.
When taking a picture, keep the following in mind:
- Keep your camera horizontally (use a tripod of place the camera on a fixed object like a table).
- Keep your camera at the same distance relative to your main object, for both pictures.
- Aim for the same point in both pictures.
- Limit the left/right distance between the two shots, do not exceed 2 to 3 inches (5 to 7.5 cm).
- Decrease Depth of Field (larger aperture, i.e. a low number) which can give the 3D picture a more dramatic effect.
You will have to experiment with that to find out what gives the desired results and what works best for you.
When taking the two pictures, a trick that can be used for the left/right distance is by using the view finder of your camera first with the left eye. For the second picture we place the viewfinder in front of the right eye, thus causing a “natural” good distance and angle between the two pictures. Do NOT move your head though when changing from left to right.
To aim, I usually use one of the center focus squares you can see in the view finder of your camera and make sure that it aims at the exact same point as with the first picture. Other camera’s might have different abilities, like for example showing a reference grid which can be used in a similar fashion.
Use the focus squares of your camera’s viewfinder
Note : Decreasing the Depth of Field can be done by playing with the aperture settings of your camera. A small or shallow Depth of Field, where only a few objects are in focus and most other objects are blurry, can significantly increase the depth perception of your 3D picture.
In the example pictures I used an aperture of f/4.5 (the flowers are in focus, but the couch is not).
A good article to read up on Aperture can be found at Digital Photography School.
I took the following two pictures for this article:
Two pictures under a slightly different angle
Since both pictures are taken under a different angle, you’d expect to see difference, no matter how subtile they are. I highlighted only a few of those differences in the next illustration – some of the differences are pretty subtile right?
Two pictures under a slightly different angle – Find the differences
Now that we have two pictures to work with, time to make our 3D picture.
p.s. : I called my example pictures “left.jpg” and “right.jpg“, indicating that the picture has been taking with the left eye or right eye.
Anaglyph – A 3D Picture for the red and blue glasses
Anaglyph 3D pictures are often lacking in colors, as the principle is based on filtering out particular colors. None the less, it can be pretty neat to play with and is very suitable for printed material.
Keep in mind though that you’ll need red/cyan 3D glasses for these pictures. For this article I purchased 3D Sunglasses Red/blue from Amazon (sturdy, fast shipping and dirt cheap), but your old fashioned cardboard models will work as well of course.
Old School 3D Glasses
In this article we will illustrate the creation of a 3D picture by using Adobe Photoshop – but any picture editing program that supports the manipulation of the Red, Green and Blue color channels. The free application Gimp or Paint.Net might be able to handle this as well but my experience with either is rather limited (any input is most welcome) and Google wasn’t able to give me a quick answer either.
For those who do not wish to work with such advanced applications like PhotoShop and Gimp, the following alternatives will do the trick as well – albeit that you have less “control” over the end result:
Feel free to experiment with the tools mentioned, from here on though we will be using PhotoShop.
The very short version for the impatient …
Copy the right image as a layer on top of the left image.
Disable the red channel in the blending options of the pasted layer.
Align the layers to a focus point.
Test the image with your 3D glasses and save it when done.
Now on to the more detailed explanation …
Step 1 – Open both pictures in Photoshop
Step 2 – Copy the Right picture over the Left picture
You can do this two ways.
Select All (CTRL+A or COMMAND+A) of the right picture,
Copy the selection (CTRL+C or COMMAND+C),
next go to the left picture,
and finally paste (CTRL+V or COMMAND+V) the copied picture onto the left picture.
Option 2 (easier):
Select the right picture,
Select the layer (right side bar, under the “Layers” tab),
Drag the layer over the left picture and drop it.
Place the RIGHT picture over the LEFT picture – by dragging a layer
After copying the right image over the left image, your left image should have 2 layers. The top one, called “Layer 1“, is your RIGHT picture, and the bottom one, called “Background” is your LEFT picture.
2 Layers – Right Picture (Layer 1) and Left Picture (Background)
Step 3 – Disable the Red Channel for blending
Double click “Layer 1” (right picture) and in the new window under “Blending Options” “Advanced Blending” “Channels” uncheck “R” (red) and click “OK“.
After this step you’ll already get a first glimpse of your 3D picture.
Prevent RED from blending
Step 4 – Aligning the Pictures
In this step we will align the right picture (Layer 1) to match the focal point in the left picture (Background).
The best way I’ve found to do this is by taking a point of an object you’d like to see “in the front” – meaning, the object you’d like to perceive as closer to you than the other objects in your new 3D picture. Take a central point in that object and move “Layer 1” around until it matches.
The moving around is best done by first selecting “Layer 1“, and using the “Move Tool” (press “V”) which can be found in the upper left corner ().
Big steps can be done with the mouse, but refined steps can be done by using the arrow keys on your keyboard.
Tip: This is a good time to pull out those silly 3D glasses and take a peek to see if you like your alignment. Play around with the object you’d like to use as your focal point. In general the most center object is a good choice to start with.
In the illustration below I zoomed in into the area I wanted the focus on – the lower sunflower.
On the left the original alignment, on the right the corrected alignment.
Align the RIGHT picture to the LEFT picture
Step 5 – Cropping and Saving the 3D Picture
Since we’ve moved, potentially anyway, the layers around, certain areas might not be covered by both images, which is something we don’t want.
It can be hard to identify which areas are not covered by both pictures – you’re looking for the outer areas where we do not see the red/blue effect and things look like a normal picture.
Select the area you want and click the crop tool ( – 5th from the top) or press “C” and press the ENTER key twice to apply the cropping.
Once done with cropping, save the file in your preferred format (typically JPEG).
Note : The illustration below is probably not the best picture I could have taken and there most certainly is room for improvement. Just keep in mind that the pictures where taken straight out of my hand without even doing an attempt to level properly, use the proper distance (I used left and right eye for the view finder), etc. Just to give you an idea what already can be achieved without any practice.
3D Picture with the flowers as the focal point
Pictures for 3D TV
The same pictures we just took, can also be used for displaying a 3D picture on your 3D capable TV.
If you haven’t already, take a look at the How 3D Movie work article.
Please note that for this trick we can only use SBS (Side-by-Side) or TB (Top-and-Bottom).
Displaying a 3D picture on your TV – Limitations
Please keep in mind that not all 3D Capable TV’s can display pictures from, for example, a USB stick and switch to 3D (SBS).
Some Vizio models for example do not allow you to switch to 3D when viewing pictures with the SmartTV apps.
– Display your pictures through a media playback device (like XBMC, Boxee, Plex, etc).
– Display your pictures by making a photo DVD (sad resolution though).
– Set your computer up as a DLNA capable “server”, since most “Smart TV’s” or Blu-Ray players can handle DLNA.
Full Color …
The previously mentioned format, for the red/blue glasses, will work on a TV as well of course and will even work in a printed format. The beauty of a 3D capable TV however is that we can format a picture in such a way that the picture will be full color – like with what we see with 3D Movies.
The most common 3D format is the so called SBS or Side-By-Side display of two pictures. So what could be more simple than that right?
Well, it is simple, but you have to keep one or the other thing in mind.
First of all, 1080p is about the maximum resolution that makes sense (unless you have a 4K TV).
So a picture of 1920 x 1080 (1080p) is enough for your TV to use all pixels. Using pictures of a higher resolution would only mean a slower display of pictures since it has to download a larger picture file and needs rescaling for display purposes.
Second of all, assuming you’ll be using SBS (Side by Side) as well: we need to put 2 squished pictures next to each other in the same 1920 x 1080 picture. One for the left eye and one for the right eye.
If you’d be using TB (Top and Bottom), you’ll have to squeeze two pictures above each other in that same space – which really didn’t look that great when I experimented with it.
In the table below an overview of the size of each individual picture in a 2-picture frame, which makes me favor using 1080p SBS.
Picture Formats for TV
Creating a SBS 3D Picture
Space to work with
In this example we will create a 1080p SBS (Side-by-Side) picture for use with a 3D TV.
1080p gives us a 1920 x 1080 pixel space to work with.
For this example I’m going to use the 2 pictures we’ve taken earlier and in my situation each of these pictures is 5184 x 3456 pixels.
Resizing and Aspect Ratio issues
The first thing you’ll probably notice is that the aspect ratio (proprotions) of your TV and picture probably will not match. Of course when your pictures are already in a 16:9 aspect ration, you will not encounter this problem.
You can test this with the following formula’s:
Aspect Ratio Comparisson
|Width Ratio = Picture Width / Screen Width
|Height Ratio = Picture Height / Screen Height
The smallest of these two ratio’s is the limiting factor.
In our example:
|Width Ratio = 5184 / 1920 = 2.7
|Height Ratio = 3456 / 1080 = 3.2
This means that with our example pictures, width is the limiting factor since the width ratio (2.7) is smaller than the height ratio (3.2).
In other words:
If we resize our picture, while maintaining aspect ratio (so without distortion), and while filling as much of the picture as we can, the width will be what will limit us. So if we resize our picture to 1920 pixels wide, then the height will be more than 1080 pixels. In our example the height would actually become 1280 pixels.
We can resolve this in two way: Either crop the picture (A) a little bit or add black bars (B) as seen with letterboxing.
Photograph to TV Aspect Ratio – Cropping (A) or Letterboxing (B)
Since our resolution is already limited, I prefer cropping (A), but this shouldn’t stop you from adding black bars instead of course.
Creating your 3D image
Now that we know the limitations of our TV and our Picture, we can go ahead and start creating our image.
Step 1 – Resize while maintaining Aspect Ratio
Open the left.jpg and right.jpg files in for example PhotoShop and resize them to a size that fits 1920×1080 closest and to your liking.
When resizing: Maintain Aspect Ratio – to prevent distortion. Most applications support this by either allowing you to lock the aspect ratio or by keeping the SHIFT key pressed while resizing.
- Select the image you’d like to resize,
- From the menu “Image” “Image Size…“,
- Make sure “Constrain Proportions” is checked,
- Enter either the width (1920) or the height (1080) to see which one fits best (I use the one with the lowest ratio – see above),
- Click “OK” when done.
Resize each picture to fit 1080p proportionally
In my example this resulted in 2 pictures of 1920×1280 pixel – note that the pictures are about 200 pixels too tall, since I’d like it to fully fill the screen, but we will correct for that later.
Step 2 – Second Resize: Squish width
If you’ve read the “How 3D Movies work” article, then you’ll already know that with a 3D SBS (Side by Side) picture, we position the two images next to each other in the 1920×1080 picture. Both pictures however are only half the width of their original size.
Note : When using TB (Top and Bottom), this of course should be half the height instead.
- Select the image you’d like to resize,
- From the menu “Image” “Image Size…“,
- Make sure “Constrain Proportions” is UNchecked,
- Enter either “960” for the width,
- Click “OK” when done.
Resize each picture to half the width
You now should be looking at something like this (assuming you’re using SBS for 3D):
Left and Right picture properly resized for SBS (Side-by-Side)
Step 3 – Merge the two Picture to one 3D Picture
Now that we have 2 properly resized images for SBS (Side-by-Side) 3D, time to merge them into one.
Create a new document in your picture editing program, and set the size to 1920 pixels wide and 1080 pixels heigh.
Place the resized left.jpg on the left, and the resized right.jpg image on the right, in your new document.
The easiest way to do this is either by dragging the layer of left.jpg on your new document, and moving it until it “locks” with the upper-left corner of your new document. Next, drag the layer of the right.jpg on your new document as well and drag it until it lock with the upper right corner.
You can of course also you copy-and-paste.
If you have both images aligned properly, then it’s maybe a good idea to either link both layers or merge both layers, so that we can move the pictures around while they stay aligned to each other.
Linking layers: Select both layers in your new document, and right click one of the selected layers. From the menu choose “Link Layers“.
Merge layers: Select both layers in your new document, and right click one of the selected layers. From the menu choose “Merge Layers“.
Now that these layers are connected, you can move the layer up or down, so you can determine what part of the picture you’d like to keep.
Once done, save the file as a JPEG picture.
3D Picture finalized
Step 4 – Testing the Picture on your TV
SmartTV Apps – Build in the TV
To test the picture we will first need to know if your TV supports switching to 3D mode when viewing pictures – if it is a SmartTV, which most 3D capable TV’s are. I’m assuming you checked this out already.
I’ve found that my Vizio TV does not allow me to switch to 3D mode when I’m viewing a picture when using one of the Apps on the TV.
Media Players – Device connected to the TV
However, viewing the image through an external Media Player, like for example XBMC, works great, since TV does allow me to switch to 3D when using XBMC. I’m confident that other media players (AppleTV, Plex, Boxee, PlayStation, etc) will allow for the same to work as well.