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203 lines
10 KiB
Markdown
203 lines
10 KiB
Markdown
# Eynollah
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> Document Layout Analysis, Binarization and OCR with Deep Learning and Heuristics
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[](https://pypi.org/project/eynollah/)
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[](https://github.com/qurator-spk/eynollah/actions/workflows/test-eynollah.yml)
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[](https://github.com/qurator-spk/eynollah/actions/workflows/build-docker.yml)
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[](https://opensource.org/license/apache-2-0/)
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[](https://doi.org/10.1145/3604951.3605513)
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## Features
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* Support for 10 distinct segmentation classes:
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* background, [page border](https://ocr-d.de/en/gt-guidelines/trans/lyRand.html), [text region](https://ocr-d.de/en/gt-guidelines/trans/lytextregion.html#textregionen__textregion_), [text line](https://ocr-d.de/en/gt-guidelines/pagexml/pagecontent_xsd_Complex_Type_pc_TextLineType.html), [header](https://ocr-d.de/en/gt-guidelines/trans/lyUeberschrift.html), [image](https://ocr-d.de/en/gt-guidelines/trans/lyBildbereiche.html), [separator](https://ocr-d.de/en/gt-guidelines/trans/lySeparatoren.html), [marginalia](https://ocr-d.de/en/gt-guidelines/trans/lyMarginalie.html), [initial](https://ocr-d.de/en/gt-guidelines/trans/lyInitiale.html), [table](https://ocr-d.de/en/gt-guidelines/trans/lyTabellen.html)
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* Support for various image optimization operations:
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* cropping (border detection), binarization, deskewing, dewarping, scaling, enhancing, resizing
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* Textline segmentation to bounding boxes or polygons (contours) including for curved lines and vertical text
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* Text recognition (OCR) using either CNN-RNN or Transformer models
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* Detection of reading order (left-to-right or right-to-left) using either heuristics or trainable models
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* Output in [PAGE-XML](https://github.com/PRImA-Research-Lab/PAGE-XML)
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* [OCR-D](https://github.com/qurator-spk/eynollah#use-as-ocr-d-processor) interface
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:warning: Development is focused on achieving the best quality of results for a wide variety of historical
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documents and therefore processing can be very slow. We aim to improve this, but contributions are welcome.
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## Installation
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Python `3.8-3.11` with Tensorflow `<2.13` on Linux are currently supported.
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For (limited) GPU support the CUDA toolkit needs to be installed. A known working config is CUDA `11` with cuDNN `8.6`.
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You can either install from PyPI
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```
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pip install eynollah
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```
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or clone the repository, enter it and install (editable) with
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```
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git clone git@github.com:qurator-spk/eynollah.git
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cd eynollah; pip install -e .
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```
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Alternatively, you can run `make install` or `make install-dev` for editable installation.
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To also install the dependencies for the OCR engines:
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```
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pip install "eynollah[OCR]"
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# or
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make install EXTRAS=OCR
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```
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## Models
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Pretrained models can be downloaded from [zenodo](https://zenodo.org/records/17194824) or [huggingface](https://huggingface.co/SBB?search_models=eynollah).
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For documentation on models, have a look at [`models.md`](https://github.com/qurator-spk/eynollah/tree/main/docs/models.md).
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Model cards are also provided for our trained models.
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## Training
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In case you want to train your own model with Eynollah, see the
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documentation in [`train.md`](https://github.com/qurator-spk/eynollah/tree/main/docs/train.md) and use the
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tools in the [`train` folder](https://github.com/qurator-spk/eynollah/tree/main/train).
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## Usage
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Eynollah supports five use cases: layout analysis (segmentation), binarization,
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image enhancement, text recognition (OCR), and reading order detection.
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### Layout Analysis
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The layout analysis module is responsible for detecting layout elements, identifying text lines, and determining reading
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order using either heuristic methods or a [pretrained reading order detection model](https://github.com/qurator-spk/eynollah#machine-based-reading-order).
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Reading order detection can be performed either as part of layout analysis based on image input, or, currently under
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development, based on pre-existing layout analysis results in PAGE-XML format as input.
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The command-line interface for layout analysis can be called like this:
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```sh
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eynollah layout \
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-i <single image file> | -di <directory containing image files> \
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-o <output directory> \
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-m <directory containing model files> \
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[OPTIONS]
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```
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The following options can be used to further configure the processing:
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| option | description |
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|-------------------|:-------------------------------------------------------------------------------|
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| `-fl` | full layout analysis including all steps and segmentation classes |
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| `-light` | lighter and faster but simpler method for main region detection and deskewing |
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| `-tll` | this indicates the light textline and should be passed with light version |
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| `-tab` | apply table detection |
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| `-ae` | apply enhancement (the resulting image is saved to the output directory) |
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| `-as` | apply scaling |
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| `-cl` | apply contour detection for curved text lines instead of bounding boxes |
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| `-ib` | apply binarization (the resulting image is saved to the output directory) |
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| `-ep` | enable plotting (MUST always be used with `-sl`, `-sd`, `-sa`, `-si` or `-ae`) |
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| `-eoi` | extract only images to output directory (other processing will not be done) |
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| `-ho` | ignore headers for reading order dectection |
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| `-si <directory>` | save image regions detected to this directory |
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| `-sd <directory>` | save deskewed image to this directory |
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| `-sl <directory>` | save layout prediction as plot to this directory |
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| `-sp <directory>` | save cropped page image to this directory |
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| `-sa <directory>` | save all (plot, enhanced/binary image, layout) to this directory |
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If no further option is set, the tool performs layout detection of main regions (background, text, images, separators
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and marginals).
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The best output quality is achieved when RGB images are used as input rather than greyscale or binarized images.
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### Binarization
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The binarization module performs document image binarization using pretrained pixelwise segmentation models.
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The command-line interface for binarization can be called like this:
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```sh
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eynollah binarization \
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-i <single image file> | -di <directory containing image files> \
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-o <output directory> \
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-m <directory containing model files> \
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```
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### OCR
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The OCR module performs text recognition using either a CNN-RNN model or a Transformer model.
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The command-line interface for OCR can be called like this:
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```sh
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eynollah ocr \
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-i <single image file> | -di <directory containing image files> \
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-dx <directory of xmls> \
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-o <output directory> \
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-m <directory containing model files> | --model_name <path to specific model> \
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```
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### Machine-based-reading-order
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The machine-based reading-order module employs a pretrained model to identify the reading order from layouts represented in PAGE-XML files.
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The command-line interface for machine based reading order can be called like this:
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```sh
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eynollah machine-based-reading-order \
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-i <single image file> | -di <directory containing image files> \
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-xml <xml file name> | -dx <directory containing xml files> \
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-m <path to directory containing model files> \
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-o <output directory>
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```
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#### Use as OCR-D processor
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Eynollah ships with a CLI interface to be used as [OCR-D](https://ocr-d.de) [processor](https://ocr-d.de/en/spec/cli),
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formally described in [`ocrd-tool.json`](https://github.com/qurator-spk/eynollah/tree/main/src/eynollah/ocrd-tool.json).
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In this case, the source image file group with (preferably) RGB images should be used as input like this:
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ocrd-eynollah-segment -I OCR-D-IMG -O OCR-D-SEG -P models eynollah_layout_v0_5_0
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If the input file group is PAGE-XML (from a previous OCR-D workflow step), Eynollah behaves as follows:
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- existing regions are kept and ignored (i.e. in effect they might overlap segments from Eynollah results)
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- existing annotation (and respective `AlternativeImage`s) are partially _ignored_:
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- previous page frame detection (`cropped` images)
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- previous derotation (`deskewed` images)
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- previous thresholding (`binarized` images)
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- if the page-level image nevertheless deviates from the original (`@imageFilename`)
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(because some other preprocessing step was in effect like `denoised`), then
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the output PAGE-XML will be based on that as new top-level (`@imageFilename`)
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ocrd-eynollah-segment -I OCR-D-XYZ -O OCR-D-SEG -P models eynollah_layout_v0_5_0
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In general, it makes more sense to add other workflow steps **after** Eynollah.
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There is also an OCR-D processor for binarization:
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ocrd-sbb-binarize -I OCR-D-IMG -O OCR-D-BIN -P models default-2021-03-09
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#### Additional documentation
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Additional documentation is available in the [docs](https://github.com/qurator-spk/eynollah/tree/main/docs) directory.
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## How to cite
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```bibtex
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@inproceedings{hip23rezanezhad,
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title = {Document Layout Analysis with Deep Learning and Heuristics},
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author = {Rezanezhad, Vahid and Baierer, Konstantin and Gerber, Mike and Labusch, Kai and Neudecker, Clemens},
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booktitle = {Proceedings of the 7th International Workshop on Historical Document Imaging and Processing {HIP} 2023,
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San José, CA, USA, August 25-26, 2023},
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publisher = {Association for Computing Machinery},
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address = {New York, NY, USA},
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year = {2023},
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pages = {73--78},
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url = {https://doi.org/10.1145/3604951.3605513}
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}
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```
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