Access 5: PDF
Published on Dec 23, 2015
Criteria for accessible PDFs
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PRESENTATION OUTLINE
What is a PDF?
- Portable Document Format
- A format or type of document
- Created by Adobe
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Company, Tool, Type of Document
- Company: Adobe = Microsoft
- Tool: Acrobat = Word
- Type: PDF = doc
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What are the criteria for accessible Adobe PDF documents?
- Text file is searchable
- Form fields are fillable
- Document structure is indicated by tags
- Reading order is clear and easy to follow
- Contains descriptive text
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What are the criteria for accessible Adobe PDF documents?
- Contains navigational aids
- Document language is specified
- Fonts allow characters to be extracted to text
- Security settings don't interfere with screen readers
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When a text file is NOT searchable, it . . .
- is an image-only scan
- is unreadable by assistive technology
- can be fixed with Occipital Character Recognition (OCR)
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An Adobe PDF document of a scanned piece of paper is inherently inaccessible because the content of the document is an image, not searchable text. Assistive technology cannot read or extract the words, users cannot select or edit the
text, and you cannot manipulate the PDF document for accessibility. Once you properly apply optical character recognition (OCR) to the scanned file, however, the image becomes searchable text with selectable graphics, and you can apply other accessibility features to the document.
An Adobe PDF document of a scanned piece of paper is inherently inaccessible because the content of the document is an image, not searchable text. Assistive technology cannot read or extract the words, users cannot select or edit the
text, and you cannot manipulate the PDF document for accessibility. Once you properly apply optical character recognition (OCR) to the scanned file, however, the image becomes searchable text with selectable graphics, and you can apply other accessibility features to the document.
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Fillable Form Fields
- Fillable means interactive
- Navigable with pre-set tab order
- Descriptions of fields can be read by a screen reader
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Some Adobe PDF documents are forms that a person is to complete by using a computer. To be accessible, these PDF forms must have interactive (fillable) form fields, descriptions of form fields that screen readers can read, and a preset
tab order that helps users navigate among the form fields.
Some Adobe PDF documents are forms that a person is to complete by using a computer. To be accessible, these PDF forms must have interactive (fillable) form fields, descriptions of form fields that screen readers can read, and a preset
tab order that helps users navigate among the form fields.
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Tagged Document Structure
- Tags identify page elements.
- (i.e. titles,headings, text, figures, tables, etc.)
- Processing varies with assistive technologies.
- Provide structure before converting to PDF.
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Accessible Adobe PDF documents use tags to indicate the structural elements of a document—such as which page elements are titles, headings, figures, text, tables, and so on—and how these elements relate to each other. These tags
are analogous to the paragraph styles, HTML tags, or XML tags you might use in a non-PDF document. Different kinds of assistive technology may process document structures in different ways. However, using a consistent tagging system nearly always produces better accessibility results for people with disabilities than if you do not use tags at all.
You can prepare some documents for proper tagging before you convert them to PDF.
Accessible Adobe PDF documents use tags to indicate the structural elements of a document—such as which page elements are titles, headings, figures, text, tables, and so on—and how these elements relate to each other. These tags
are analogous to the paragraph styles, HTML tags, or XML tags you might use in a non-PDF document. Different kinds of assistive technology may process document structures in different ways. However, using a consistent tagging system nearly always produces better accessibility results for people with disabilities than if you do not use tags at all.
You can prepare some documents for proper tagging before you convert them to PDF.
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Clear Reading Order
- Logical
- Easy to follow
- Designed for screen readers
- Tagged
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An accessible Adobe PDF document has a logical, easy-to-follow reading order. Assistive technology is designed to read page content in the order in which it receives the content from an application
such as Acrobat or Adobe Reader. If the content is not presented to the assistive technology in a logical reading order (such as if a heading comes after its body text, or a figure caption is not near its figure description), people with disabilities may not be able to understand the content.
Tagging a PDF document usually establishes an appropriate, structured reading order.
An accessible Adobe PDF document has a logical, easy-to-follow reading order. Assistive technology is designed to read page content in the order in which it receives the content from an application
such as Acrobat or Adobe Reader. If the content is not presented to the assistive technology in a logical reading order (such as if a heading comes after its body text, or a figure caption is not near its figure description), people with disabilities may not be able to understand the content.
Tagging a PDF document usually establishes an appropriate, structured reading order.
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Descriptive Text (alt-text)
- Graphics
- Charts
- Form fields
- Links
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Accessible Adobe PDF documents also have descriptive text, usually called alternate text, to describe special items on a page, such as illustrations, graphs, charts, form fields, and links. Screen readers and other assistive technology
typically cannot read graphical elements. By adding alternate text, you enable the technology to interpret the element and read a description of the element to the user. And although screen readers can state that a form field is present and can read URLs out loud, you can give the user a more meaningful context for navigating them if you also provide descriptive text about these elements.
Accessible Adobe PDF documents also have descriptive text, usually called alternate text, to describe special items on a page, such as illustrations, graphs, charts, form fields, and links. Screen readers and other assistive technology
typically cannot read graphical elements. By adding alternate text, you enable the technology to interpret the element and read a description of the element to the user. And although screen readers can state that a form field is present and can read URLs out loud, you can give the user a more meaningful context for navigating them if you also provide descriptive text about these elements.
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Navigational Aids
- Links
- Bookmarks
- Useful and frequent headings
- Detailed table of contents
- Preset tab order for forms and embedded links
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Accessible Adobe PDF documents also have many navigational aids for the user—links, bookmarks, useful and frequent headings, a detailed table of contents, and an optimized, preset tab order for forms and embedded links.
These navigational aids enable users to go directly to a particular place in a document instead of reading through it page by page.
You can set most navigational aids during conversion to PDF from authoring applications.
Accessible Adobe PDF documents also have many navigational aids for the user—links, bookmarks, useful and frequent headings, a detailed table of contents, and an optimized, preset tab order for forms and embedded links.
These navigational aids enable users to go directly to a particular place in a document instead of reading through it page by page.
You can set most navigational aids during conversion to PDF from authoring applications.
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Document Language
- Specify the document language.
- Allows screen readers to change languages
- Allows text to be rendered more accurately
- Screen readers can load correct punctuation rules.
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While some screen readers are designed to read documents in a particular language, specifying the document language in an accessible Adobe PDF document can benefit those screen readers that can switch to other languages during operation.
While some screen readers are designed to read documents in a particular language, specifying the document language in an accessible Adobe PDF document can benefit those screen readers that can switch to other languages during operation.
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About the Font
- Fonts allow characters to be extracted to text
- Sufficient underlying text information allows for accuracy
- Allows for accuracy with assistive technologies
- Makes the content more understandable
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Another characteristic of an accessible Adobe PDF document is that the fonts within it contain enough information for Adobe Reader or Acrobat to correctly extract all the characters to text for purposes other than displaying text on
the screen. For example, the application extracts characters to text when users listen to text by using a screen reader or the Read Out Loud tool in Adobe Reader or Acrobat, or when they copy, paste, or save text to a file.
If the font's underlying information is sufficient, Adobe Reader and Acrobat can extract each character correctly each time someone does these tasks. If the font's information is insufficient, the application cannot substitute characters correctly, and the output is faulty. For instance, a screen reader or the Read Out Loud tool may seem to ignore words or characters, or users may get question marks, black rectangles, or similar marks when they copy, paste, or save a PDF file as text.
Another characteristic of an accessible Adobe PDF document is that the fonts within it contain enough information for Adobe Reader or Acrobat to correctly extract all the characters to text for purposes other than displaying text on
the screen. For example, the application extracts characters to text when users listen to text by using a screen reader or the Read Out Loud tool in Adobe Reader or Acrobat, or when they copy, paste, or save text to a file.
If the font's underlying information is sufficient, Adobe Reader and Acrobat can extract each character correctly each time someone does these tasks. If the font's information is insufficient, the application cannot substitute characters correctly, and the output is faulty. For instance, a screen reader or the Read Out Loud tool may seem to ignore words or characters, or users may get question marks, black rectangles, or similar marks when they copy, paste, or save a PDF file as text.
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Security Settings
- can interfere with screen readers
- setting to "restrict copying" causes interference
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The final characteristic of an accessible Adobe PDF document is that its security settings do not interfere with screen readers. You can typically specify that no part of an accessible PDF document is to be copied, printed, extracted, commented on, or edited. The setting to restrict copying, however, could interfere with a screen reader's ability to
read the document, since the screen reader's functionality depends on a sort of copying of the document's text in order to play it back.
The final characteristic of an accessible Adobe PDF document is that its security settings do not interfere with screen readers. You can typically specify that no part of an accessible PDF document is to be copied, printed, extracted, commented on, or edited. The setting to restrict copying, however, could interfere with a screen reader's ability to
read the document, since the screen reader's functionality depends on a sort of copying of the document's text in order to play it back.
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For more information, visit:
W3C PDF Techniques
for WCAG 2.0
http://bit.ly/1vQTmNJ
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