I Was watching "How to make a Lightsaber in Blender | The easy way" where it taught me how to make a lightsaber using a mask. Towards the end of the video,I clicked render animation and when i checked my output file, the pictures had no mask around them. I used a image sequence.
- Make sure you have your mask selected from the drop-down in the Mask node
- Make sure your output is not only connected to the Viewer node but also to the Composite node output. Ensure that "Use Nodes" at the bottom of the Node editor is checked.
- Make sure the mask layer you are using is enabled to render
Please update with more information if this does not solve your problem.