Audio Visual Design Guidelines

Image Contrast

294 views November 21, 2018 November 21, 2018 aetm 0

Viewers rely on displayed materials to communicate information in such a way that it can be assimilated correctly and efficiently in a way that supports their purpose.

No displayed image is defined by contrast alone, but it remains one of the most critical criteria. Without adequate contrast; text is difficult to read  and colours are inadequately saturated.

When designing systems, we seek to provide adequate contrast applicable to the task – and to replace years of ‘rules of thumb’ ANSI standards are being released:

  • ANSI/InfoComm (AVIXA) 3M Projected Image System Contrast Ratio (PISCR) was ratified in 2011; and
  • ANSI/AVIXA V201.02 Direct View Display Image System Contrast Ratio is in development

The four viewing categories that are used for other AVIXA vision standards were first defined in PISCR. In typical learning environments;

  • The majority of spaces will be characterised as Basic Decision Making
    “The viewer can make basic decisions from the displayed image. The decisions are not dependent on critical details within the image, but there is assimilation and retention of information. The viewer is actively engaged with the content (e.g., information displays, presentations containing detailed images, classrooms, boardrooms multi-purpose rooms, product illustrations).”
  • A smaller number of spaces will be Analytical Decision Making
    “The viewer can make critical decisions by the ability to analyze details within the displayed image. The viewer is analytical and fully engaged with these details of the content (e.g., medical imaging, architectural/engineering drawings, forensic evidence, photographic image inspection).
  • Screening rooms and multipurpose lecture theatres may be categorised as Full Motion Video
    “The viewer is able to discern key elements present in the full motion video, including detail provided by the cinematographer or videographer necessary to support the story line and intent (e.g., home theater, business screening room, broadcast post-production).”
  • Passive Viewing will not generally apply as we are generally seeking more than “non-critical or informal viewing of video and data”.

Designers must always take care not to use PISCR or DVDISCR to supplant dedicated standards for broadcast and cinema (SMPTE), medical imaging (DICOM and others), photographic analysis or similar. AVIXA standards provide performance criteria for these spaces in typical ‘pro AV’ context.

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