proofpress

Open-source pieces of a print-on-demand pipeline, extracted from production use.

proof-pdf

verify runs four layers, each of which can be switched off:

• PDF/A with veraPDF (--flavour 2b by default; --no-pdfa to skip).
• PDF/X-4 structure: page boxes, /Trapped, the GTS_PDFX output intent and the XMP version key (--no-pdfx).
• Geometry: trim and bleed against the finished size you expect. Runs only when --trim-mm is given (--bleed-mm, --tolerance-mm).
• Colour: total ink coverage (--max-tac, 300% default), stray RGB (--strict-cmyk), effective image DPI (--min-dpi, 300 default), overprint and rich-black small text (--no-colour). Overprinting 100% K text is fine; overprint on anything else is flagged, and white that overprints is an error (it adds no ink, so it vanishes on press). A page that uses transparency must blend in the output intent's colour space (a mismatch is an error, an undeclared space a warning).
• K-only text (opt-in, --k-only-text): text painted with any ink but K (a four-colour build, RGB, a spot or a pattern) is an error.
• Proofing (the text and lines a page paints, measured in page points; see below).

inspect reports what is in a PDF without judging it, and texlog lints a LaTeX build log. preview rasterises each page and draws the trim, bleed and safe guides from the PDF's own boxes, so a geometry finding can be seen.

pip install proof-pdf          # Python 3.15; needs verapdf and gs (Ghostscript) on PATH

proof-pdf verify job/ --trim-mm 105x148 --bleed-mm 3 --exclude '*_preview.pdf'
proof-pdf verify job/ --exempt 'manual.pdf=internal docs, never printed'   # listed with the reason, never fails
proof-pdf verify job/ --k-only-text       # house rule: text is K-only
proof-pdf verify card.pdf --json          # machine-readable findings, for CI
proof-pdf preview card.pdf --dpi 150
proof-pdf --version                       # version, plus the commit when built from an image

• Arguments are files or directories; a directory expands to every PDF beneath it, minus --exclude globs (relative to that directory).
• --exempt GLOB=reason declares a file out of scope. It is still listed, with the reason, and never fails; the glob matches at any directory level (res/**, *_preview.pdf). Unlike --exclude, which drops files silently, an exemption stays visible in CI output.
• A check whose tool is missing fails, it is never skipped: a file that can't be confirmed must not read as OK.
• A veraPDF "device colour without an output intent" failure carries a hint saying what to add.
• Errors fail the file and exit 1. Warnings are advisory. --quiet prints nothing, for exit-code-only use.

verify -j N checks N files at once (default: up to 4). veraPDF and Ghostscript run as subprocesses and the PDF checks in worker threads, so nothing blocks the event loop.

As a library the API is async: await proof_pdf.core.verify_file(path, profile) returns a FileReport of Findings, and await proof_pdf.core.verify_files(paths, profile, jobs=4) returns one report per path in order. See proof_pdf.models.Profile.

Proofing

Beyond the standards, verify can hold a PDF to the rules a print job usually has. Missing glyphs and fonts are checked by default (they are exact); every rule that needs a number or a name takes it from you and has no default, because a size floor, a safe margin or a printing condition is a house rule, not something to infer.

Contrast is deliberately not WCAG, which is a screen model. Colours are converted through an ICC profile (the PDF's own output intent, or --proof-profile) to Lab*, the paper is the page's white, and the L* difference is reported with CIEDE2000 beside it. The background of a text run is the last filled shape painted under it, else the paper; text over an image or shading is reported as not measured, never as a pass. Clipping and transparency are not modelled, so treat it as the design's intent. CMYK ink needs a CMYK profile to be measured through; without one the check says so and fails.

--require-bleed catches the white sliver after cutting: for each side of a page that has a bleed zone (BleedBox, else MediaBox, larger than the TrimBox), a filled path, image or shading that reaches the trim edge must run to the bleed edge, within half a point. White fills count; text and strokes do not; objects inset from the trim are ignored. Clips (W/W*) are followed, so art clipped back to the trim fails and art clipped to the bleed box passes. It judges geometry, not the printed result, and its limits are: transparency and soft masks are taken as opaque; a non-rectangular clip counts as its bounding extent; a Form XObject's own /BBox is not applied. An object that stops short is excused wherever other artwork covers the bleed strip beside it, whatever the paint order, so a panel at the trim over a full-bleed background passes. Pages without a TrimBox or bleed zone are skipped (the page-box checks report them) and a rotated page gets a warning that it was not checked.

Printer profiles

A job's numbers come from its printer's spec, so keep them in a file committed with the job instead of repeating flags in CI. proof-pdf.toml (or a [tool.proof-pdf] table in pyproject.toml) is found by walking up from the working directory, or named with --config / PROOF_PDF_CONFIG. Each table is a command and each key one of its options, written with dashes or underscores (or as the flag is spelled):

[verify]
trim-mm = "105x148"
bleed-mm = 3
min-text-pt = 6
min-stroke-pt = 0.25
safe-mm = 3
output-condition = "FOGRA51"
allow-spot = ["Dieline"]
proof-profile = "profiles/PSOcoated_v3.icc"     # relative to this file

[verify.exempt]
"manual.pdf" = "internal documentation, never printed"

[profiles.deluxe.verify]                         # chosen with --profile deluxe; overrides [verify]
bleed-mm = 5

A flag on the command line beats the file, and the file beats the built-in default. Unknown tables and keys are errors, so a typo cannot silently switch a check off.

proof-pdf inspect card.pdf                # fonts (embedded?, .notdef), text colours and sizes, spot inks, images, contrast
proof-pdf inspect card.pdf --json         # the same as data, for other tools
proof-pdf texlog build/card.log           # dropped characters, TeX errors, undefined references, substituted fonts, overfull boxes
proof-pdf verify card.pdf --safe-mm 3 --min-text-pt 6 --min-delta-l 30 --proof-profile FOGRA51.icc

texlog reads the log because the PDF can't tell the whole story: pdfTeX drops a character the font lacks (LuaTeX typesets .notdef, which verify finds), and an undefined reference only prints as ??. Missing characters, TeX errors and undefined references are errors; font substitution, package warnings, a pending rerun and overfull boxes are warnings (--max-overfull-pt N promotes the worst overfull boxes).

The library offers the same as data: proof_pdf.inventory.inspect_pdf(path) returns plain dataclasses, and the checks are functions over an opened pikepdf.Pdf.

Docker images

docker run --rm --user "$(id -u):$(id -g)" -v "$PWD":/work releaseart/full verify job/ --trim-mm 105x148
docker run --rm --user "$(id -u):$(id -g)" -v "$PWD":/work releaseart/lualatex lualatex -interaction=nonstopmode book.tex

releaseart/lualatex is TeX Live 2025 (the collection-latex, luatex, latexrecommended and fontsrecommended sets plus a few common packages) on Debian, with no Java or Python. Add your own packages in a derived image with tlmgr install. releaseart/full adds Ghostscript, veraPDF (with a JRE) and proof-pdf.

Both are published for linux/amd64 and linux/arm64. :latest is the most recent build: the weekly one of main (Mondays, which also picks up base-image updates) or a tagged release, whichever is newer. :1.2.3 comes from a git tag and :tl2025 tracks the TeX Live year. Each image reports its commit in PROOFPRESS_REVISION and the OCI revision label.

Development

Python 3.15 and PDM.

git config core.hooksPath .githooks   # ruff + pyright before each commit
pdm install
bin/autoformat.sh                     # ruff format + fix, pyright
bin/test.sh                           # pytest (integration tests skip without veraPDF and gs)
bin/docker/build.sh && bin/docker/smoke.sh
bin/docker/test.sh                    # the whole suite inside the full image, integration tests included

See CONTRIBUTING.md. To release, add the version to CHANGELOG.md and push a tag: git tag v1.2.3 && git push origin v1.2.3. The tag is the version; it publishes to PyPI (TestPyPI first), creates a GitHub Release and pushes both images.

Licence

Apache-2.0. Third-party terms, including Ghostscript (AGPL-3.0) and veraPDF, are in NOTICE.