https://github.com/travisbrown/rotation-rs
Document rotation detection
https://github.com/travisbrown/rotation-rs
Last synced: over 1 year ago
JSON representation
Document rotation detection
- Host: GitHub
- URL: https://github.com/travisbrown/rotation-rs
- Owner: travisbrown
- License: bsd-3-clause
- Created: 2020-06-27T17:04:06.000Z (about 6 years ago)
- Default Branch: main
- Last Pushed: 2023-01-20T22:42:03.000Z (over 3 years ago)
- Last Synced: 2025-03-20T00:38:21.710Z (over 1 year ago)
- Language: Rust
- Size: 2.15 MB
- Stars: 7
- Watchers: 2
- Forks: 0
- Open Issues: 22
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Document rotation detection
This is my first attempt at compiling Rust to [WebAssembly](https://webassembly.org/).
It's a Saturday project and probably won't go anywhere or be maintained in any way. I know nothing
about WebAssembly and very little about Rust, so it's unlikely to illustrate best practices.
The application is an OCR preprocessor that takes a scanned document (which may be rotated) and
attempts to estimate the angle of rotation. It does this by computing the Fourier transform of the
image using [RustFFT](https://github.com/awelkie/RustFFT).
If this was real code it'd probably be better to use
[Rust's OpenCV bindings](https://github.com/twistedfall/opencv-rust),
but I had to stick to pure Rust libraries since the goal was to run this in the browser via
WebAssembly.
The code includes ideas from [here](https://stackoverflow.com/a/33707537/334519) and
[here](https://blog.stackpath.com/image-manipulation/), as well as the official Rust documentation.
If you have Rust, Cargo, and npm installed and you've run `cargo install wasm-pack` at some point,
you should be able to build the web application like this:
```bash
$ wasm-pack build
$ cd www/
$ npm install
$ npm run start
```
The application should then be available at [localhost:8080](http://localhost:8080/):
You can also build a native CLI, which you can test against synthetic data like this
(if you have [ImageMagick](https://imagemagick.org/) installed):
```bash
$ cargo build --release
$ convert -rotate 5 examples/lorem.png lorem-5.png
$ target/release/rotation lorem-5.png
5.0040045
$ convert -rotate 7.5 examples/lorem.png lorem-7.5.png
$ target/release/rotation lorem-7.5.png
7.487998
$ convert -rotate -1.8 examples/lorem.png lorem-1.8.png
$ target/release/rotation lorem-1.8.png
-1.746
```
It's not great, but it's not terrible for a few dozen lines of code.
The CLI can also save the FFT spectrum as an image:
```bash
target/release/rotation --output examples/fft.png lorem-7.5.png
```
Which looks like this:
