Usage

Python API

Reading a file

nupdf.core.read_pdf() opens a PDF or converts a supported image format (JPEG, PNG, GIF, RAW) to PDF on the fly.

from nupdf.core import read_pdf

reader = read_pdf("document.pdf")
print(f"Pages: {len(reader.pages)}")

# Works with images too — saves document.pdf.pdf alongside the image
reader = read_pdf("scan.jpg")

Rotating pages

nupdf.core.rotate_pages() rotates all or a subset of pages.

from nupdf.core import rotate_pages

# Rotate all pages 90° clockwise
rotate_pages("input.pdf", "output.pdf", angle=90)

# Rotate only pages 0 and 2 (0-indexed) by 180°
rotate_pages("input.pdf", "output.pdf", pages=[0, 2], angle=180)

Merging files

nupdf.core.merge_pdfs() combines several PDF/image files.

from nupdf.core import merge_pdfs

merge_pdfs(
    ["front.pdf", "back.pdf"],
    "merged.pdf",
    recto_verso=False,
    same_file=None,
    bookmark=True,
)

Recto-verso interleaving

If you have a duplex scanner that outputs fronts and backs in separate files:

merge_pdfs(
    ["fronts.pdf", "backs.pdf"],
    "interleaved.pdf",
    recto_verso=True,
    same_file=True,   # fronts and backs are separate files
    bookmark=False,
)

If all pages are in a single file (fronts in the first half, backs in the second):

merge_pdfs(
    ["both_sides.pdf"],
    "interleaved.pdf",
    recto_verso=True,
    same_file=None,
    bookmark=False,
)

Page-range syntax (GUI)

When entering pages in the GUI input field, use the following syntax:

Input	Pages selected (1-indexed)
`3`	Page 3
`1-4`	Pages 1, 2, 3, 4
`1-3;5`	Pages 1, 2, 3, 5
`2;4-6;9`	Pages 2, 4, 5, 6, 9
(empty)	All pages

Supported input formats

Extension(s)	Notes
`.pdf`	Native; no conversion needed
`.jpg` / `.jpeg`	Converted to PDF via Pillow
`.png`	Converted to PDF via Pillow
`.gif`	Converted to PDF via Pillow
`.raw`	Converted to PDF via Pillow

GUI controls

Control	Description
Insert files	Open a multi-file dialog
Insert folder	Recursively add all supported files in a tree
Up / Down	Reorder the selected files
Merge multiple files?	Combine all listed files into one PDF
Add bookmarks	Insert PDF outline entries named after files
Recto verso?	Interleave pages for duplex scans
Fronts/backs separate	Fronts and backs are in distinct files
Rotation angle	Clockwise degrees (e.g. 90, 180, 270)
Pages to rotate	Page-range string; empty = rotate all
Select saving path	Choose where to write the output PDF
Start	Execute the operation