# pdfluent-ccitt
A pure-Rust **CCITT** decoder for Group 3 and Group 4 facsimile-encoded
bitmap images, used to decode CCITT-compressed images embedded in PDF
documents.
`pdfluent-ccitt` is one of the open-source foundation crates used by the
[PDFluent](https://pdfluent.com) commercial Rust PDF SDK. It is published as
**MIT OR Apache-2.0** so it can also be used standalone.
This crate is a **fork of [`hayro-ccitt`](https://github.com/LaurenzV/hayro)**
by Laurenz Stampfl. The fork is maintained by PDFluent for coordinated
exact-version pinning across the workspace.
## What this crate gives you
- Decode CCITT G3 / G4 (one-dimensional and two-dimensional) bitmap data
(the `/Filter /CCITTFaxDecode` PDF stream)
- Pure Rust — memory-safe, no C dependency, compiles to WebAssembly
CCITT is the dominant compression scheme for monochrome scanned documents
in older PDFs and for fax workflows.
What this crate is **not**:
- Not a CCITT encoder
- Not a generic image processing library
## Usage
This crate is most often invoked transitively via PDFluent's PDF stream
filtering layer. Direct usage:
```toml
[dependencies]
pdfluent-ccitt = "0.2"
```
For PDF-level rendering, prefer the
[`pdfluent`](https://crates.io/crates/pdfluent) facade.
## License
**MIT OR Apache-2.0** — preserved from upstream `hayro-ccitt`.
```
Copyright (c) Laurenz Stampfl (hayro-ccitt)
Copyright (c) 2026 Innovation Trigger BV (PDFluent fork)
```
See [LICENSE-MIT](LICENSE-MIT) and [LICENSE-APACHE](LICENSE-APACHE).
## Links
- PDFluent SDK: <https://pdfluent.com>
- `cargo add pdfluent` (full SDK): <https://crates.io/crates/pdfluent>
- Upstream hayro: <https://github.com/LaurenzV/hayro>