SPARCLUR - Some PDF Analyzers and Renderer Comparators: LevelUp Research

SPARCLUR is a collection of wrappers around PDF parsers and renderers, plus tools for comparing and analyzing their output. It is useful for inspecting validity, rendering, text extraction, parser traces, incremental updates, and parser repeatability.

API documentation is published at Read the Docs. The notebooks in examples provide runnable, end-to-end examples.

See it in action here: https://youtu.be/6I6E1N3CJzQ

Installation

pip install sparclur

SPARCLUR supports Python 3.10 and newer. The parser wrappers may additionally need their respective command-line tools installed; see Parsers.

The Python-backed parser adapters and Streamlit interface are intentionally optional. Install only what you plan to use:

pip install --upgrade "sparclur[all]"     # Every supported optional feature
pip install "sparclur[mupdf]"             # PyMuPDF adapter
pip install "sparclur[pdfium]"            # PDFium adapter
pip install "sparclur[pdfminer]"          # PDFMiner adapter
pip install "sparclur[ui,mupdf,pdfium]"   # UI plus common renderers

For local development, create an environment and install the development extra:

python -m venv .venv
.venv/bin/python -m pip install -e ".[dev]"

Contents

• Parsers
  • Arlington DOM Checker
  • Ghostscript
  • MuPDF
  • PDFCPU
  • PDFium
  • PDFMiner
  • Poppler
  • QPDF
  • XPDF
• Config
• Tools
  • Parser Wrappers
  • Parser Trace Comparator
  • PDF Renderer Comparator
  • PDF Text Comparator
  • Spotlight
  • Roll Back
  • Detect Chaos
  • Highlight
  • Floodlight
  • Astrotruther
• Report generation
• Streamlit Interface
• Acknowledgements

Parsers

Parser availability is discovered at runtime. A parser can be made available by installing its Python extra, putting its command-line tool on PATH, or setting its binary location in configuration. The interface selects only parsers that are currently available by default.

Arlington DOM Checker

Clone the repository and build its TestGrammar tool. Point SPARCLUR at the top-level clone directory so it can locate both the DOM files and executable.

https://github.com/pdf-association/arlington-pdf-model

Ghostscript

Install Ghostscript with your preferred package manager and expose gs on PATH, or configure its executable path.

https://www.ghostscript.com/

MuPDF

Install the PyMuPDF-backed adapter with pip install "sparclur[mupdf]". The mutool binary is additionally required for MuPDF trace collection and reforging; simple rendering and text extraction only require the optional Python package.

https://mupdf.com/

https://pymupdf.readthedocs.io/en/latest/

PDFCPU

PDFCPU is a Go-based PDF processor. Install or build PDFCPU and make its binary available through PATH, configuration, or parser construction.

https://pdfcpu.io/

PDFium

Google's PDF rendering software. Install its adapter with pip install "sparclur[pdfium]".

https://pdfium.googlesource.com/pdfium/

https://github.com/pypdfium2-team/pypdfium2

PDFMiner

PDFMiner is a Python-based parser. Install its adapter with pip install "sparclur[pdfminer]".

https://pdfminersix.readthedocs.io/en/latest/

Poppler

Poppler and XPDF can have binary-name collisions. Configure the selected tool's path explicitly if both are installed.

https://poppler.freedesktop.org/

QPDF

Install QPDF and add its binary to PATH, configure it, or supply it at construction time.

https://qpdf.sourceforge.io/

XPDF

Poppler and XPDF can have binary-name collisions. Configure the selected tool's path explicitly if both are installed.

https://www.xpdfreader.com/

Config

SPARCLUR reads YAML defaults for parser classes, such as binary paths, timeouts, and render settings. Use examples/sparclur.yaml as a reference. The normal editable file is available from Python:

from sparclur.utils import get_config, get_config_path, update_config

print(get_config_path())
update_config({"Poppler": {"binary_path": "/path/to/poppler/bin"}})
print(get_config())

update_config() always writes to this user-owned file. It uses the platform-standard per-user configuration directory (~/Library/Application Support/sparclur/sparclur.yaml on macOS) and creates parent directories as needed. Set SPARCLUR_CONFIG=/path/to/sparclur.yaml to use an explicit file instead.

Configuration is layered from an environment/virtual-environment file, a checkout-local sparclur.yaml, legacy user configuration, then the user-owned file. Later layers override earlier values without discarding unrelated parser settings. The packaged YAML remains a template so its example paths are never applied automatically. Malformed YAML produces a clear configuration error instead of silently falling back to defaults.

For a project-specific or shared configuration file, set SPARCLUR_CONFIG to its path before starting Python or the UI. Use update_config() for personal settings; it safely merges just the values supplied into the user-owned YAML.

Tools

See the examples directory for Jupyter notebooks that showcase the following tools.

Parser Wrappers

SPARCLUR's extensible parser wrapper APIs support:

• Document rendering
• Text extraction
• Trace message collection and normalization
• Document reforging for cleaning and recovery
• Font, object, and image-data extraction

Parser Trace Comparator (PTC)

Gather and normalize warning and error messages from extant parsers.

PDF Renderer Comparator (PRC)

The PRC compares different renderers over the same documents and can also be used to visualize the differences and produce a similarity metric.

PDF Text Comparator (PXC)

APIs for extracting and comparing text between parsers.

Spotlight

Runs selected available capabilities for each parser and creates document reforges. It records validity classifications and similarities across the original and reforged versions, with tabular, heatmap, and interactive sunburst reports.

Roll Back

Detects incremental updates and exposes or saves any specific version. It also compares text and rendered output between consecutive versions and returns plots of those metrics.

Detect Chaos

Repeats parser operations and reports evidence of nondeterministic behavior. It is a screen rather than a proof: a clean run means no difference was observed in the requested comparisons.

Highlight

Analyzes explicitly modified PDFs alongside their known originals to find rendering differences introduced by the modification. It requires a genuine original-to-modified mapping.

Floodlight

Runs a collection of parsers over PDFs and produces a flat, analysis-ready record of their parser-level results.

Astrotruther

Trains models to classify PDF validity from normalized parser traces. It requires a labeled training set.

Report generation

Native report generation creates a readable HTML dossier together with an evidence bundle containing CSV and JSON tables, image evidence, and a manifest of the source document and analysis options. It does not require Pweave or an IPython kernel.

from sparclur import DocumentReport

report = DocumentReport(
    "sample.pdf",
    parsers=["Ghostscript", "MuPDF", "Poppler", "PDFium"],
)
report.write_bundle("out/sample-report")
report.write_pdf("out/sample-report.pdf")  # requires sparclur[reports]

The dossier includes parser validity, normalized traces (PTC), text-comparison data (PXC), renderer-comparison data and figures (PRC), and an extracted predecessor when incremental updates are present. Use BatchReport to produce a triage index with one evidence dossier per PDF. SparclurReport remains as a compatibility facade; its generate_report() method now creates the native HTML bundle. Install pip install "sparclur[reports]" for PDF renditions; this uses WeasyPrint and may require its platform libraries (Pango) as documented by the WeasyPrint installation guide.

Streamlit Interface

PyPI installation

Install every supported optional feature, including the UI, and run the packaged command:

pip install --upgrade "sparclur[all]"
sparclur-ui

For a smaller install, use the UI extra alone or combine it with specific parser extras, for example pip install "sparclur[ui,mupdf,pdfium]".

The command launches a Streamlit web app for exploring uploaded PDFs with the PTC, PRC, PXC, Metadata, and Raw views. It accepts standard Streamlit options, such as sparclur-ui --server.port 8501. In PRC, choose renderer pairs and press Refresh comparison when ready; pair-selection changes do not rerun the comparison immediately.

Source checkout

Clone the repository, create and activate a virtual environment, then install the UI extra:

git clone https://github.com/levelupresearch/sparclur.git
cd sparclur
python -m venv .venv
source .venv/bin/activate
python -m pip install -e ".[ui]"
./light_the_sparclur.sh

The checkout launcher starts the same Streamlit interface using the activated environment. The app opens with a standard PDF upload control; after selecting a document, use the sidebar to choose PTC, PRC, PXC, Metadata, or Raw output.

Acknowledgements

This material is based upon work supported by the Defense Advanced Research Projects Agency (DARPA) under Contract No. HR0011-18-S-0054. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Defense Advanced Research Projects Agency (DARPA).

Distribution Statement "A" (Approved for Public Release, Distribution Unlimited).

Contributors

• Shawn Davis
• Dan Becker
• John Kansky
• J. Wilburn
• James Devens
• Emma Meno
• Liz Parker
• Peter Wyatt
• Tim Allison