If you place a picture directly on or near the red trim line at the
edge of the page, the editor will automatically move that picture
either 3mm outside the red line or 6mm inside the red line.
is because the trimming of an album is not always millimetre perfect.
Therefore, if you want your images to bleed off the page edge then they
need to go all the way to the outside blue line. Alternatively if you
want some background showing around your pictures, then they need to be
at least 6mm inside the red line to ensure the background looks even.