How to start
To try out the BlueBox effect, you will have to make some suitable video recordings.
You are going to need a scene for the background and a further scene for the foreground.
The background scene can be whatever you like. You can use a scene from your video "archive" if you like. For this example we are using a shooting of a paddle streamer. The background scene can be of any content. The foreground scene must be a bit more special: The color of this scene must be as regular as possible throughout the whole picture for it to be see-through. Try a blue sheet hung-up on the wall or similar. You can also use other colors but try to avoid using black or white. For this purpose, we have recorded an toy soldier in front of a blue paper.
Now record both scenes. We recommend you use a high video quality. This prevents picture artifacts appearing, which in turn could prove to be rather disturbing on the outlines.

Your project should now contain both of these scenes. Trim these scenes down to a length of about 5 seconds each. Now place the scenes into the story-board in a specific order: First, add the background scene and secondly the foreground. Remember: The foreground contains single-colored elements like the blue wall while the background scene contains many different elements.

The order of the scenes is of prime importance: First the background and then the foreground
You now have to add the "BlueBox" effect. You will find it in the transitions menu. Insert the effect (as is normally done) between the background and foreground scene. The effect has four options, of which all are of importance. These options are explained during the course of this example.

1. The color selection
This step is for selecting the transparent color of the foreground scene.
You will have to select the color of the background like the blue paper in this example. This is done using the "color choice" button.
This button allows you to expand and place a rectangle for marking the color of the paper. Pressing the button displays the first frame of the foreground scene. You now have to define a rectangle capturing the largest possible part of the blue paper. This rectangle is not allowed to capture elements of the object (in this case the toy soldier) as the object is not supposed to become transparent.
To define the rectangle, you have to use two buttons: Position and Size.
First, select "Size" and define a relatively small rectangle. To do this, roll the trackball to the top left -the frame will react respectively. Once you have reached the desired size, click onto the left trackball button. Now press "Position". You can now define the position of the rectangle using the trackball. It is important that the top left corner is placed correctly. This is because the bottom right corner is dependent on the "Size" setting.
As you can tell from the three examples below, there are several possible ways of placing the mask window. Choose the rectangle which captures as many different shades on the paper (in other words: some of the well lit parts and some of the more darker parts of the paper) as possible!
It is very important to capture as many different shades as possible. This is the secret behind the BlueBox technique.

2. The color span
You now have a base color which will become transparent. However, sometimes the wall / the background is not lit optimally and thus does not appear in one particular shade of color. The results will be better if the shade of the color is constant but even the best constellation will result in a color deviation be it the "noise" generated by the camera itself.
It is important to compensate this color deviation. This is the purpose behind the "Color span" button. This button sets a kind of tolerance for the masked color. A low tolerance (=color span) requires a perfect background color whereas a high tolerance allows for a badly lit environment.
Select a value of 90% for this example. You can optimize this later.

3. The image range (Include Area and Exclude Area)
In using these buttons, you can mark the part of the screen to be transparent. Outside this range, the foreground scene will be shown (even if the masked color appears here).
In most cases, the picture range will be your whole screen. This also makes sense for our example. There might be a time when you want to have a smaller range. If you are working with a scene consisting of mountains, a blue sky and a blue lake and want to exchange the sky with your livingroom, you ’ll end up having the lake being transparent too. Defining the picture range is done in much the same way as previously explained with the masking color (color choice) – the buttons "Size" and "Position" are used here as well.

The preview
If you think you have selected the correct color and are happy with the tolerance and picture range – make a test!
To do this, click onto "Preview". You will now see a small version of the video with the BlueBox effect.
Are you happy with the result? If yes, you can go on to making the first actual rendering process. Remember that the preview is a bit rough compared to the final result. A test rendering is required!
If you are not happy with the preview (or with the final version), make corrections using the color span button. If you are still seeing parts of the blue background, set the color span setting a bit higher. If, on the other hand, you have noticed that parts of the foreground object (in our case the toy soldier) are transparent, lower the color span level.
Check the preview as long as is required until you have an optimal result.

TIP: If the running time (most of the time 1 second) is too short, use the length gadgets to select to 2 seconds or longer (using the "Xs" gadget). The maximum length is the length of the shorter of the two scenes.
Users of Casablanca Prestige, Kron or Casablanca Avio with Pro-Pack can use the Full Screen preview function to get a better preview!

Still no perfect result?
If you are still having parts of the background coming through, or parts of the foreground object are still transparent (in our case the toy soldier) try to correct the color span level. Maybe you have placed the rectangle in the wrong place or have defined a too small a size for it. If the foreground person comes into touch with the image range border, avoided Problems by leaving a small safety space between them!
If all your attempts fail,the problem will probably be the actual BluBox background itself or maybe a color in the foreground object.
You will most definitely get problems if colors similar to the background ’s appear in the foreground. Don ’t use a blue shirt in front of a blue wall! Even a blue eye color would cause problems.

The light could also be problematic. The background should have one regular color throughout and you should have no shadows falling onto it. The color of the wall should be as bright as possible.
The color range setting should not be set to higher than 95% in normal usage. Should this be necessary (to get the background completely transparent), the problem lies elsewhere: The setting of the mask color is wrong or perhaps your "studio" is just not set up optimally. (Don ’t worry -the requirements are relatively low.).

 
Scene 1 (background)

 
Scene 2 (object in front of a blue background)

Result