Changing the Alpha Type of a Video Clip

If you imported a video clip with transparency using the Import Videos/Images as Clips dialog, you were prompted to select the transparency type of your video clips in the Alpha Type drop-down.

The alpha type is used to indicate to Storyboard Pro how the colour values in the semi-transparent pixels in your video were encoded relative to their alpha values, so that Storyboard Pro can properly blend them with the other visual elements in your animatic. If you don't select the proper alpha type for your video clip, its semi-transparent pixels may appear too dark, too light, opaque or even the wrong colour.

Which alpha type was used to encode the semi-transparent pixels in your video may not be obvious to figure out, as it depends on the software you used to export your video. Hence, trial and error may be needed to figure out which alpha type to apply to your video clips. If you selected the wrong alpha type for a video clip, you can quickly change it by right-clicking on the clip in the Timeline view.

The following Alpha Types are supported for video clips:

  • Ignore Alpha: Display every pixel in the video clip as opaque, without demultiplying their colour values or blending them with other visual elements in your animatic.
  • Premultiplied with Black: The colour values of semi-transparent pixels in the video have been encoded so that the more transparent they are, the closer to black they are. When a video that is premultiplied with black is loaded in a software that does not support transparency, it appears blended with a black background. Select this to make Storyboard Pro reverse this premultiplication so that the video clip blends properly with other visual elements in your animatic.
  • Premultiplied with White: The colour values of semi-transparent pixels in the video have been encoded so that the more transparent they are, the closer to white they are. When a video that is premultiplied with white is loaded in a software that does not support transparency, it appears blended with a white background. Select this to make Storyboard Pro reverse this premultiplication so that the video clip blends properly with other visual elements in your animatic.
  • Straight: The colour of semi-transparent pixels in the image is encoded independently from their transparency. When a video clip that is not premultiplied is loaded in a software that does not support transparency, semi-transparent pixels simply appear fully opaque, making its edges appear pixelated.
NOTE The Alpha Type for a video clip only affects movie files. If you imported an image with transparency as a video clip, its alpha type is presumed to be straight.
  1. In the Timeline view, right-click on the video clip.
  2. In the contextual menu, select Alpha Type and, in the sub-menu, select the proper alpha type for your clip.
  1. In the Timeline view, right-click on the video-clip.
  2. In the contextual menu, select Alpha Type > Straight.
  3. Move the timeline playhead over the video so that it is visible in the Stage or Camera view.
  4. Look at the semi-transparent pixels in the video for inaccuracies, and do one of the following:
    • If the semi-transparent pixels in the video appear properly, leave it as is.
    • If the semi-transparent pixels in the video appear too dark, right-click on the video clip again and select Alpha Type > Premultiplied with Black.
    • If the semi-transparent pixels in the video appear too light, right-click on the video clip again and select Alpha Type > Premultiplied with White.