While the still component of your cinemagraph is typically selected in-app from your video, Cinemagraph Pro allows you to use a separate image. You can do this by importing a still image into Cinemagraph Pro.
There may be times where your still image appears stretched or distorted upon import. This occurs when the aspect ratio of the still image does not match that of the video.
When you import a still image into Cinemagraph Pro, it'll automatically occupy the entire frame. If the still image isn't the same size as your video, it will be resized so that it’s stretched to fit the video frame.
To resolve this, ensure the dimensions of your still image are the same as your video. You can check the dimensions of your source video and image from desktop or Finder by using the keyboard shortcut Command-i and reviewing the dimensions of each file.
Export your still image from Cinemagraph Pro if you want to add a logo or do fine-tune touchups. As long as you don't crop your still image using a third-party editing application, the still image will maintain the same aspect ratio as your video.