sometimes ya download a book and ya get the thing as a bunch of 'spreads', meaning, two pages at once. heres my way of mushing the thing back into a reglar type book
pdf of 'spreads'
go ahead and make a shortcut for duplicate layer and make it one key you dont have to press shift or anything for because youre about to be mashing that a ton
get a good rhythm going of your chosen letter and the up arrow. if the up arrow doesn't take you to the next layer, click in the layer box and then it should.
select a region that corresponds to the left page with ye rectangular select tool
if you havent already, set another easy keyboard shortcut to layers-crop-to-selection. make sure it's the layer one and not the image one!!! if its not the layer one youre gonna have a bad time/make me a sad panda/et cetera and so forth
one more key shortcut if you want to use the same rhythms i do... i recommend it, i recommend groove-based working generally. set a key (k) to toggle layer visibility. youre gonna start with only one layer visible and bring the others in as you need them.
now you're gonna get into a more complicated rhythm of Up Up K S, if you've used the letters i have.
then select the right hand page and groove your way up the ladder in the same way
and now "the tricky part" which is lining up all these result layers in a way that isnt a nightmare
make all layers visible visible (shift+click an 'eye' icon, maybe a couple times to cycle to 'all layers visible')
go and select the 'alignment' tool, which you might have to find by right-clicking on the 'select' tool
click and drag across the entire canvas to get all the layers in the mix
center everything relative to the first layer for rn. horizontally.
reduce the canvas size to the size of the largest page youve ended up with
now center everything according to image size
and now you have a bunch of pages ready to be cleaned up in whatever way. yay!!!