Update: OCR and IIIF

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# 3 - Images and Text

[https://labs.onb.ac.at/en/tool/sacha/](https://labs.onb.ac.at/en/tool/sacha/)

[https://labs.onb.ac.at/en/dataset/akon/](https://labs.onb.ac.at/en/dataset/akon/)

[https://labs.onb.ac.at/en/dataset/anno/](https://labs.onb.ac.at/en/dataset/anno/)

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### In this block

* Overview IIIF

* Overview OCR formats

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* Example: Create IIIF collection from SPARQL query result

* Example: Download pre-downsized images for machine learning

* Example: Download OCR text

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## Overview IIIF

[http://iiif.io/](http://iiif.io/)

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### What is IIIF?

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* International Image Interoperability Framework ([http://iiif.io/](http://iiif.io/) - well written, worth a read)

* Standardised method of **describing and delivering images over the web**

* Community that develops APIs and implements them in Software

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<img src="./media/api_puzzle_pieces.png" style="max-height: 500px;" />

*Image courtesy of [https://github.com/IIIF/training](https://github.com/IIIF/training), CC-BY 4.0*

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### Why would I use this?

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#### If you want to display images

* If you want to use one of several nice viewers for images (zoom, rotate, fullscreen ootb)

* If you want to include image data hosted elsewhere

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#### If you want to process images

* If you want structured access to potentially huge sets of images

* If you want included metadata

* If you want to resize images *before* downloading

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### How would I use this?

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* You could access an **image** directly (Image API)

  * Parameters can be changed in the URL

  * [https://iiif.onb.ac.at/images/AKON/AK035_199/199/full/full/0/native.jpg](https://iiif.onb.ac.at/images/AKON/AK035_199/199/full/full/0/native.jpg)

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* You could get a **manifest** JSON (Presentation API)

  * Contains images and metadata

  * [https://iiif.onb.ac.at/presentation/AKON/AK035_199/manifest/](https://iiif.onb.ac.at/presentation/AKON/AK035_199/manifest/)

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* You could get a **collection** JSON (Presentation API)

  * Contains manifests and possibly other collections

  * [https://iiif.onb.ac.at/presentation/collection/pydays19](https://iiif.onb.ac.at/presentation/collection/pydays19)

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### Pics or didn't happen!

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* The ONB Labs viewers use IIIF: [https://labs.onb.ac.at/en/dataset/akon/](https://labs.onb.ac.at/en/dataset/akon/)

**TODO**: Available viewers, available data sources (europeana, ?), applications

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``` python

```

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* Awesome IIIF-related resources : [https://github.com/IIIF/awesome-iiif](https://github.com/IIIF/awesome-iiif)

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* [https://showcase.iiif.io/](https://showcase.iiif.io/)

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* IIIF Presentation API

    * returns JSON-LD structured documents that together describe the structure and layout of a digitized object or other collection of images and related content

    * [https://iiif.io/api/presentation/2.1/](https://iiif.io/api/presentation/2.1/)

    * [https://iiif.onb.ac.at/presentation/ABO/+Z196807705/manifest/](https://iiif.onb.ac.at/presentation/ABO/+Z196807705/manifest/)

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* IIIF Image API

    * requesting and delivering images on the Web

    * [https://iiif.io/api/image/2.1/](https://iiif.io/api/image/2.1/)

    * Image Request URI Syntax

        * {scheme}://{server}{/prefix}/{identifier}/{region}/{size}/{rotation}/{quality}.{format}

        * [http://iiif.onb.ac.at/images/ABO/Z196807705/00000009/full/full/0/native.jpg](http://iiif.onb.ac.at/images/ABO/Z196807705/00000009/full/full/0/native.jpg)

        * 90 degree rotation: [http://iiif.onb.ac.at/images/ABO/Z196807705/00000009/full/full/90/native.jpg](http://iiif.onb.ac.at/images/ABO/Z196807705/00000009/full/full/90/native.jpg)

        * "Articulus Quartus": [https://iiif.onb.ac.at/images/ABO/Z196807705/00000009/pct:0,0,100,33/full/0/native.jpg](https://iiif.onb.ac.at/images/ABO/Z196807705/00000009/pct:0,0,100,33/full/0/native.jpg)

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## Overview OCR formats

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* ALTO (Analyzed Layout and Text Object)

    * OCR (Optical Character Recognition) data representation format

    * XML Schema

    * [https://github.com/altoxml](https://github.com/altoxml)

    * [https://www.loc.gov/standards/alto/](https://www.loc.gov/standards/alto/)

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* 3 ALTO main elements

    * `<Description>`

        *  metadata and general settings (e.g. measurement units) about the ALTO file

    * `<Styles>`

        *  text and paragraph styles

    * `<Layout>`

        * content information

        * subdivided into `<Page>` elements

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![ALTO page element](./media/alto.png)

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* hOCR

    * alternative to ALTO

    * based on XHTML

    * not used in the ONB Labs

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``` python

```