Faz a "imposição" de páginas de um zine em um A3

fitz-zine-impostion.py

"""
Make a PDF A3 zine combining 8 pages from a source PDF

WIP: I'd like to have an option for the 9th page (index=8) to be a poster in the backside or not.
-------------------------------------------------------------------------------
License: GNU GPL V3
(c) 2023 Alexandre Villares

Based on https://github.com/pymupdf/PyMuPDF-Utilities/blob/master/examples/combine-pages/combine.py
(c) 2018 Jorj X. McKie

Dependencies
------------
PyMuPDF (the fitz engine)

Usage
-----
python combine.py input.pdf

|----|----|----|----|
| 0d | 7d | 6d | 5d |
|----|----|----|----|
| 1u | 2u | 3u | 4u |
|----|----|----|----|

|----|----|----|----|
|                   |
|        8s         |
|                   |
|----|----|----|----|

N = page 0-based 
u = normal orientation
d = upside down (rotated 180)
s = big poster (rotated 90)

Notes
-----
(1) Output file is chosen to have A3 landscape pages. Input pages are scaled
    maintaining side proportions.
"""

import fitz, sys

infile = sys.argv[1]
src = fitz.open(infile)
doc = fitz.open()  # empty output PDF

height, width = fitz.paper_size("a3")  # A3 output page format
# define the 4 rectangles per page
r0 = fitz.Rect(0, 0, width / 4, height / 2) # top left rect
r7 = r0 + (r0.width, 0, r0.width, 0)  
r6 = r7 + (r0.width, 0, r0.width, 0)   
r5 = r6 + (r0.width, 0, r0.width, 0)    # top right
r1 = r0 + (0, r0.height, 0, r0.height)  # bottom left
r2 = r1 + (r0.width, 0, r0.width, 0)
r3 = r2 + (r0.width, 0, r0.width, 0)
r4 = r3 + (r0.width, 0, r0.width, 0)# bottom right
r8 = fitz.Rect(0, 0, width, height)
# put them in a list
r_tab = [r0, r1, r2, r3, r4, r5, r6, r7, r8]

front_and_back = False
big_poster = True
poster_offset = 0
# now copy input pages to output
for spage in src:          
    if (spage.number - poster_offset) % 8 == 0:  # create new output page
        page = doc.new_page(-1, width=width, height=height)
# WIP
#         if not front_and_back:
#             poster_offset += 1
#             if big_poster:
#                 # add poster here
#                 continue
    # insert input page into the correct rectangle
    r_position = (spage.number - poster_offset) % (9 if big_poster else 8)
    # imposition rotation rule
    rotation = (180 if r_position in (0, 7, 6, 5)
                 else 90 if r_position == 8 else 0) 
    page.show_pdf_page(
        r_tab[r_position],  # select output rect
        src,  # input document
        spage.number,
        rotate=rotation
    )  # input page number

# by all means, save new file using garbage collection and compression
doc.save("output.pdf", garbage=4, deflate=True)

Este é aquele formato de zine que você corta com o estilete uma linha reta na parte de cima das páginas 2 e 3 (que as separam das páginas 6 e 7) e isso pemite dobrar de forma a virar um "livrinho".