How Disabled use PDF Documents

In this section we want to look at how disabled persons interact with PDF documents.

Please keep in mind that all disabilities can occur in combination. A person who is both motor disabled and visually impaired is more dependent on accessibility.

Interactive elements like flickering are distracting for persons with seizure disorders like epilepsy. It can also affect persons with autism.

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blind persons

At this point, blind persons means persons who work with assistive technologies that are typical for blind persons. There are also blind persons who can still work on the computer with a screen magnifier or other aids. They may be legally blind but work like visually impaired persons. We look at how this works in the “Visually Impaired persons” section.

Blind persons typically use an assistive technology called screen reader. The software translates the visual content into a form that can be understood by the blind. In the case of graphics, for example, the alternative text is output, in the case of tables the position of the table cell and its content, in the case of forms the type of input field and, if available, its content or status.

The output takes the form of speech or Braille on special devices. The screen reader relies on information being stored correctly, i.e. in an accessible manner. For example, if the name of the input field is missing, the blind person does not know what to enter there.

A screen reader can only output information line by line, which means a blind person sees all content linearly, even if it is visually arranged next to each other. That is why the reading and tabbing and reading order are extremely important for a blind person. If text columns or tables are not correctly linearized, in the worst case they are completely incomprehensible to the blind.

visually impaired persons

The effects of visual impairment vary. Essentially, however, three effects can be distinguished:

  • poor visual acuity: small content in particular, such as text that is too small, appears very blurred
  • limited field of vision: sharp vision is limited to a small area weak
  • color and contrast: the affected person has problems viewing content with low contrast to see or distinguish.

Visually impaired persons have different options for accessing content. You can make settings within the operating systems that make viewing easier. For example, you can set higher-contrast color schemes or display larger text. They can also zoom content larger or smaller.

Visually impaired persons use so-called screen magnifiers. This allows the content of the screen to be enlarged up to 64 times. This means that a single program icon or letter fills the entire screen. As a rule, however, less strong degrees of magnification are used.

The magnifiers can also customize the color schemes as well. One possibility is the inversion of the screen. For example, black text on a white background becomes white text on a black background. This increases legibility for those affected and reduces glare.

There is also the Reflow mode mentioned elsewhere, which is probably not known to most of those affected.

At high magnification, multi-column content is a challenge. Since you have to scroll both horizontally and vertically, it's easy to miss content if it's centered or right-aligned. It is to be hoped that documents can be linearized based on the reading order in the future.

motor disabled persons

In the case of motor disabled persons, the ability to move the limbs is limited or completely absent. There are rather slight limitations in the mobility of the hands up to paraplegia from the neck down, which means that hands and arms cannot be used.

For this group of persons, bookmarks are important so that they can move quickly through a document.

There are three ways for persons with motor disabilities to use computers: eye, movement, tongue and voice control.

The motion-based controls work essentially like using a mouse, it just takes longer With voice control.

For forms, it is important that the accessible name matches the visual caption. This is important because a specific field can be jumped to by voice input, for example.

Reading tools

Few programs for reading PDF files meet the requirements for accessible PDF documents. The most important program is Adobe Reader on the desktop.

PDF UA has still not reached the quality that is possible with websites, both in terms of creation and use. As a user, I keep coming across badly tagged documents, incorrectly structured tables and unusable forms. Remember that we are talking about documents that have been explicitly made accessible. Such problems also occur on the web, but much less frequently and easier to circumvent. If a table in a PDF document or just a form doesn't work, you have to get help from a non-disabled person.

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