Spine cutter alignment

[Fast Fox]

I am using a publisher to print a photographic book. They have told me that for single images that stretch across the 2 page spread, I will need to adjust the image by making a copy of the image and stretching the middle apart of the image. This is because the printing will hide some of the middle of the photo as it stretches across the middle of the spine. Therefore I have to add some of the image in the middle where it will be hidden by the book spine. I have attached a file which the publisher explains to me how to do this in Adobe Publisher. Unfortunately I do not understand how to do this in Affinity Publisher. Can anyone hep me?  Thanks Robin

[firstdefence]

What they are doing is using two images with each half of the image masked.

Like this, I staggered the images to show how they are masked.

Clipping example.afpub

[Fast Fox]

25 minutes ago, firstdefence said:

What they are doing is using two images with each half of the image masked.

Like this, I staggered the images to show how they are masked.

Clipping example.afpub

 

[Fast Fox]

Thank you very much. That makes a bit more sense.