# rescribe.xyz/preproc package

This package contains various image processing methods which are
useful for preprocessing page images for OCR. It also contains
several commands in the cmd/ directory which can be used to
preprocess images directly.

This is a Go package, and can be installed in the standard go way,
by running `go get rescribe.xyz/preproc/...` and documentation
can be read with the `go doc` command or online at
<https://pkg.go.dev/rescribe.xyz/preproc>.

If you just want to install and use the commands, you can get the
package with `git clone https://git.rescribe.xyz/preproc`, and then
install them with `go install ./...` from within the `preproc`
directory.

## Commands

There are several commands in the cmd/ directory which are useful
in their own right as well as serving as examples of using the
package.

  - binarize     : binarises an image using the sauvola algorithm
  - pggraph      : creates a graph showing the proportion of black
                   pixels for slices through an image
  - preproc      : binarises and wipes an image
  - preprocmulti : binarises and wipes an image with multiple
                   binarisation ksize values
  - wipe         : wipes sections of an image that are outside an
                   area detected as content

## Bugs

The integral image operations don't produce exactly the same result
as their non-integral image counterparts. The difference is small
enough that it has little effect on the output images, but it ought
to be identical.

## Contributions

Any and all comments, bug reports, patches or pull requests would
be very welcomely received. Please email them to <nick@rescribe.xyz>.

## License

This package is licensed under the GPLv3. See the LICENSE file for
more details.