Editing JPEG still frames

In my FCP X project timeline, I have many JPEG still frames. They look clear when the playhead in the timeline is parked on the clip, but the resolution degenerates when I hit play. This poorer quality is encoded when I export. Any suggestions on how to maintain the picture resolution?

Would need to know how you're exporting it.

Ken...
Thanks for this. So I then re-edit each still frame back into my timeline, replacing the JPEG's I'm now using? Will I need to do this process for every JPEG in my timeline? I have nearly 100.

Did it work out okay using the method in the articleI?

If so I don't think that you should have to re edit. Do one or two as a test.

--ken

What are your Sequence settings for the time line?

What is the frame size of the Jpegs?

Have you rendered the timeline?

Can I assume that you are not running 'Proxy'?

Ken...
Your suggestion to export a freeze frame of my JPEG's worked for me. I exported the freezes as TIFF's, then replaced the JPEG's in my timeline. They rendered much clearer, so I'm all good, thanks to you!