Originally Posted by skoolpsyk
I wonder if modern viewers would give the same results as Joe's study of eye fatigue. I know that when I first started getting into AV back in the early 90s, I used to feel eye strain/visual fatigue often. But now that I spend so much more time in front of a screen, I don't feel it hardly at all...
The Society of Motion Picture and Television Engineers (SMPTE) has a current research committee working on revising human factors standards and recommended practices for HDR cinema, post production, broadcast, and home environments. Joe Kane was the chair of the professional monitor working group that developed SMPTE's previous publication pertaining to this topic.
Our eyesight changes gradually as we age. No two individuals have identical sensitivity when it comes to perception. However, the human factor studies Joe refers to incorporate a relatively wide sampling of types of viewers. The resulting recommendations are offered to approximate an "average" viewer's needs. It must be kept in mind that the fundamental basis of these studies is how humans respond to constantly fluctuating levels of emitted and reflected light in a darkened environment.
In addition to iris activity, as Joe described, another fatigue-inducing element in the human visual system is brightness adaptation. There are multiple parts of this that occur in the physical optical system and brain when ambient conditions change from dark to light. The retina has electrical and chemical processes that can take up to about a half hour to fully adapt to a very dark environment. Fatigue is typically induced in most viewers when very dark to very bright shifts occur in random sequence throughout many programs. This is quite common when TV shows are edited to stimulate interest, or when commercials are inserted into broadcast programs.
A great experiment for the average viewer is to turn the sound off, plus the room lights off while watching a typical broadcast TV show at night. Turn your back to the TV and observe how much the light reflected in the room changes in brightness, plus how frequently and erratically it occurs. This effect is somewhat comparable to driving on an interstate highway late at night toward oncoming vehicle headlights, a notoriously fatiguing activity.
Many other of Joe's comments pertaining to viewing environment conditions focus upon various ways room design can negatively affect the audience experience. This technical paper is the result of studying Joe's writings, among many others, then endeavoring to summarize and demonstrate key practical principles: "The Importance of Viewing Environment Conditions in a Reference Display System."
Best regards and beautiful pictures,
G. Alan Brown, President
SMPTE, THX, ISF, Lion AV Consultants
"Advancing the art and science of electronic imaging"