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Alpha channel in video editing

Alpha channel in video editing

Everyone has seen this effect at least once in a movie or in advertisements: you have a black background with white text and underneath this “mask” the video images appear. The technical term for such an effect is “alpha channel” and today, we will take a look at how easy it is to do this yourself. First of all, we will need a black and white picture. We can create such a picture easily with the free MAGIX Photo Designer 7. The picture should measure 1024 x 576. If you do not wish to work with this widescreen format, use the measurement 720 x 576. The complete mask needs to be positioned in front of a black background. Then, we need to think of a text to use. In this example we will use ‘MAGIX Moments’.

It is important to use a font which can be featured in bold, too. Any font in bold leads to a great result and prevents letters from merging with each other. Just test different fonts to see which you like the most.

When the image is finished, save it as a file. I will save this image to our workshop in .png format. Now open MAGIX Movie Edit Pro 17 Plus and drag & drop a few videos or photos into the timeline. After doing so, we will think of an optimal place to position the mask we have just created. It’s best to place it directly below the motif we want to use it for – just like you can see on the screenshot.

An alternative to green screen – keying with alpha channel mask

Now, we want the black background to stay and the white letters to disappear in order to be able to see the video images. To do so, we need to click on the fourth tab “Effects” directly above the Media Pool and select “Video Effects“. Then, select the “Chroma key” option. Here you will find options for blue screen and greenscreen, and a black and white box. We will click on the created mask to activate it. You will know it is activated by the orange color. You can now see the complete mask over the video recording within the preview window. However, the image below is not yet visible. To see it, click on the white box in the effects tab.

Now the white letters turn transparent and the video image slowly becomes visible. Play the clip to see the full result. Finally, we don’t want the mask to appear out of nowhere, but want it to show up very slowly. Such a transition can be achieved by using the square handles. Click on the top corners of the mask with your mouse and slowly drag these corners to the middle of the mask. This has to be done at the beginning as well as at the end. Now play the complete clip again to take a look at the result.

In this example, we used text on black background. However, you can also choose to create and insert geometric forms – the process stays the same, no matter what you create. Try out for yourself and get an idea of how easy and user-friendly it is to work with the alpha channel.

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