Here is how you put in a solid full screen color image into your Final Cut Pro editing project.
Supporting Outside Clips
When using external footage, such as stock newsreel or educational film clips, or photos you may end up having them be much smaller than your correct aspect ratio. Blowing them up could end up making them too distorted because of their low resolution and you may want to separate them from the rest of the clips to show them as the object of the discussion. Instead of just integrating them with the rest of the footage showing them a little smaller in the center of the screen is a great way to change the perspective. Often times this is used in documentary film over an interview clip as B-roll. A problem that occurs in this situation is that a small video size will not cover up the entire image of the interview clip it is layering over. You can try to disconnect the video of the interview clip from this part, but that is awkward an unnecessary. Instead you can just use a color solid to fill the back.
Inserting the Color Solid
To do this go to the Browser and go to the Effects tab. Go to the Video Effects folder and select the Video Generator sub folder. From here you select the Color Solid option from the menu and drag and drop it into the timeline. Make sure to put the color solid under the video clip you are trying to support. Trim the color solid clip so it matches the video clip perfectly in size in the timeline. You may want to try and nest the two clips once you have finished sizing it just to stay more organized in your primary timeline. Usually the default color for the color solid is blue so that it is easier to be seen for any changes. Select it and bring it into the Viewer and change the color to black, as long as that is what you prefer.
The color solid then gives the feeling of blank space behind the said clip and you can then apply any sizing or motion you want to in front of that clip. This is a standard for isolating images in Final Cut Pro and is used consistently, especially during historical montage sequences or cultural documentary films.