Overview

I am sharing the results of querying GPT-4 about ALTO (Analyzed Layout and Text Object) XML.

https://www.loc.gov/standards/alto/

Required Elements

ALTO (Analyzed Layout and Text Object) XML is an XML schema for representing OCR-generated text and its layout. Its structure is very flexible, with many elements and attributes, but the required elements are limited.

The simplest form of ALTO XML has the following hierarchical structure:

  1. <alto>: The root element. It must have @xmlns and @xmlns:xsi attributes indicating the version of the ALTO XML schema. It must also have two child elements: <Description> and <Layout>.

  2. <Description>: Contains file metadata. This element itself has no required child elements, but typically includes child elements such as <MeasurementUnit>, <sourceImageInformation>, and <OCRProcessing>.

  3. <Layout>: Represents the physical layout of the file. It must contain one or more <Page> child elements.

  4. <Page>: Represents a single page. This element should have three required attributes: @ID, @WIDTH, and @HEIGHT. It can also have one <PrintSpace> child element.

The above elements represent the most basic structure of ALTO XML, but many more elements and attributes can be used to express the text content and its layout in detail. For example, elements such as <PrintSpace>, <TextBlock>, <TextLine>, and <String> can be used to describe the physical arrangement and content of the text in detail. For details on each element and attribute, please refer to the ALTO XML schema documentation.

The OCRProcessing Element

The OCRProcessing element is used within the <Description> element of ALTO XML. This element stores information about a specific OCR process. It can have the following sub-elements:

  • ocrProcessingStep: Describes each step of the OCR processing. This element can have attributes such as processingDateTime, processingAgency, processingSoftware, processingStepSettings, and processingStepDescription.

Below is an example of using the OCRProcessing element:

<De<DsOecCOsrRoCciPc<<<<<oRrprrppp/ppcPitoPrrr<<<prrrrpicrooosssrooPotoeocccooooccrcinsceeefffceeoeo>sessstttesscsnisssswwwssses>nsiiiaaasiisiginnnrrrinnsnngggeeenggigIgDASCNVgSSn>DSagoraeSttg=ttefemroeeS"eentaesfpptOpTcwt>itSDeC>iyaoSoweepRm>rronats>1eAe>f>rtc">g>StSeir>2eowo>ni0nfafgp2ctrtst3ywew>i-aaSo0NrNren8aeaet>-mmtD0eCeVie1<r<ensT/e/rgc0passsr0rtoi<i:oofo/p0crtnpt0ew<ri:sNa/oo0sarscn0imeoe<neNfso/g<atsfpA/mwirgseantoeo>rghcnfeSeectVtsyweeps>arprirsSoneiecgCoteDrntsae>istanietgnTosgir>m>set>ep</processingStepDescription>

Here, processingDateTime represents the date and time when the OCR processing was performed, and processingAgency represents the name of the organization that performed the processing. processingSoftware contains information about the software used for OCR processing, and processingStepSettings and processingStepDescription provide the settings and description of the processing steps, respectively.

In this way, the OCRProcessing element can be used to store detailed information about OCR processing within ALTO XML.

Summary

There may be errors, but I hope this is helpful.