Import thumbnails are faint.

Hi, I'm new to Mac but didn't have this issue 2 days ago.  If I am in photoshop and select File, Import, 2/3rds of the thumbnails in the selected photo are very faint and hard to see and the other 1/3 are fine.  It still lets me select the faint ones, it's just frustrating because it makes them harder to see.  I don't know what is causing this.