This paper is about changes in the author's visual perception over most of his lifetime, but in particular in the period
before and after cataract operations. The author was myopic (-3D) until the operations, and emmetropic afterwards –
with mild astigmatic aberrations that can be compensated with cylindrical spectacles, but in his case rarely are, because
of the convenience of not needing to wear distance glasses in daily life anymore. The perceptual changes concern color
vision, stereopsis and visual acuity. The post-cataract changes were partly expected, for example less yellow and more
blue images, but partly wholly unexpected, and accompanied by feelings of excitement and pleasure; even delight. These
unexpected changes were a sudden, strongly increased depth vision and the sensation of seeing suddenly sharper than
ever before, mainly at intermediate viewing distances. The visual acuity changes occur after, exceptionally, his distance
glasses are put on. All these sensations lasted or last only for a short time. Those concerning stereopsis were dubbed
'super depth', and were confined to the first two months after the second cataract operation. Those concerning acuity
were termed 'super-sharpness impression'; SSI. These can be elicited more or less at will, by putting on the spectacles
described; but will then disappear again, although the spectacles are kept on. Ten other ex-cataract patients have been
interviewed on their post-operation experiences. The 'super-depth' and SSI experiences may be linked to assumed
neurophysiological mechanisms such as the concept of Bayesian reweighting of perceptual criteria.
Everybody views and uses color from early childhood onwards. But this magnificent property of all objects around us turns out to be elusive if you try to specify it and communicate it to another person. Also, people often don’t know what effects color may have under different conditions. However, color is so important and omnipresent, that people can hardly avoid to 'rely on it' – so they do, in particular on its predictability. Thus, there is a discrepancy between the seeming self-evidence of color and the difficulty in specifying it accurately, for the prevailing circumstances. In order to analyze this situation, and possibly remedy it, a short historic perspective of the utilization and specification of color is given. The 'utilization' includes the emotional effects of color, which are important in, for instance, interior decorating but also play a role in literature and religion. 'Specification' begins with the early efforts by scientists, philosophers and artists to bring some order and understanding in what was observed with and while using color. Color has a number of basic functions: embellishment; attracting attention; coding; and bringing order in text by causing text parts presented in the same color to be judged as belonging together. People with a profession that involves color choices for many others, such as designers and manufacturers of products, including electronic visual displays, should have a fairly thorough knowledge of colorimetry and color perception. Unfortunately, they often don’t, simply because for 'practitioners' whose work involves different aspects, applying color being only one of those, the available tools for specifying and applying color turn out to be too difficult to use. Two consequences of an insufficient knowledge of the effects color may have are given here. The first of these consequences, on color blindness, relates to 8% of the population, but the second one, on reading colored text, bears on everyone. Practical guidance is given, especially on color and legibility. Anyway, the available tools mentioned, such as chromaticity diagrams and color spaces, are mainly the responsibility of the CIE. It would therefore be a laudable initiative if the CIE would not only refine their present systems, but devote some time and energy to the development of a simpler color specification and measurement system. With that it would be worth trying ergonomics research principles, to begin with end-user involvement: investigating what color science practitioners really want and need.
Age influences all bodily functions, also vision. Therefore, the effects of age on vision should be mirrored in
ergonomic requirements laid down in display standards such as ISO 9241-300/307, 'Electronic visual display
requirements'. However, this is only true to a limited extent - just as is the case with other standards dealing with
ergonomic requirements, because developers of such standards do not possess the necessary specific knowledge.
It therefore was an important step by ISO and IEC to publish in 2001 ISO/IEC Guide 71: 'Guidelines for
standard developers to address the needs of older persons and persons with disabilities'. This guide was followed
by a more specific and detailed Technical Report from ISO, ISO/TR 22411, as well as by 'Guidelines on
Accessibility' from CIE. These three guidelines are reviewed. The paper concludes with developments around
ISO 9241-300/307 in general, especially future additions on autostereoscopic displays and electronic paper. As
to the former, the visual fatigue often accompanying viewing 3D displays needs methods for characterizing and
validating such displays, to reduce visual fatigue as much as possible. Standardizing certain properties of
electronic paper is an example of the present pro-active way of working of ISO/TC159/SC4/WG2, 'Visual
Display Requirements', that developed ISO 9241-300/307.
This paper gives an overview of the visual representation of reality with three imaging technologies: painting,
photography and electronic imaging. The contribution of the important image aspects, called dimensions
hereafter, such as color, fine detail and total image size, to the degree of reality and aesthetic value of the
rendered image are described for each of these technologies. Whereas quite a few of these dimensions - or
approximations, or even only suggestions thereof - were already present in prehistoric paintings, apparent
motion and true stereoscopic vision only recently were added - unfortunately also introducing accessibility and
image safety issues. Efforts are made to reduce the incidence of undesirable biomedical effects such as
photosensitive seizures (PSS), visually induced motion sickness (VIMS), and visual fatigue from stereoscopic
images (VFSI) by international standardization of the image parameters to be avoided by image providers and
display manufacturers. The history of this type of standardization, from an International Workshop Agreement to
a strategy for accomplishing effective international standardization by ISO, is treated at some length. One of the
difficulties to be mastered in this process is the reconciliation of the, sometimes opposing, interests of vulnerable
persons, thrill-seeking viewers, creative video designers and the game industry.
It is often believed that modern viewers of visually presented information need to be pleased or kept concentrated by
feeding them several types of input simultaneously: the primary information and, moreover, what are regarded as
embellishments such as figuratively structured instead of plain uniform background of folders and slides in
presentations. However, there are many cases whereby the utility or efficiency of transmission of presented information
and aesthetical aspects inherent to this presentation are opposed. Examples for static images are: color combinations of
foreground and background in text and figures such as graphs that impede legibility; the use of low-contrast secondary
information in the form of figures or text in the same plane as the intended primary information; and gloss, causing
specular reflection and sometimes glare, applied to bezels of visual displays or to the face of the display itself.
Aesthetically intended aspects of dynamic images, such as flashing parts, may even cause health hazards, for example
Being aware of the possible opposition of utility and attractiveness means that a sensible choice can be made for the
relative strengths of the information-bearing and the aesthetic factors - including a 'strength zero' of the latter, if need be.
We can all use, to a larger or lesser extent, the technological marvels that surround us and that we often depend on;
without, however, really understanding how they function. But designing, buying, using and maintaining those devices
does require a certain level of knowledge on the basics of that functioning, if one wants to avoid problems. Displays are
a worth-while example of the marvels meant because of their ubiquity in modern life. A standard on displays, especially
a new one, could provide the knowledge meant - and anyway deserves to be known by the people frequenting the EI
Conferences. Therefore, a progress report on the production of the new ISO display standard is presented here for the
third time. The standard contains: an introduction; all definitions used; the visual requirements for displays; three
different methods to measure display properties; and analysis and compliance methods to verify whether a particular
display complies with the requirements set. The standard is meant to provide knowledge for designers of displays, their
users, and those that procure displays for these users. It is set up in such a way that emerging display technologies as are
used in, for instance, SED and OLED, can be incorporated easily.
A new ISO standard for visual displays: "Ergonomic requirements and measurement techniques for electronic visual displays" is soon to be released as a Draft International Standard. The core of the new standard is the part with generic ergonomic requirements for visual displays. Three parts of the standard describe three types of measurements: electro-optical ones, to be used in general; user performance test methods, for innovative displays for which no electro-optical methods exist; and field assessment methods, to be used outside of the laboratory, under the conditions of use at the workplace. The last part of the standard describes five compliance routes and procedures for five different display technologies and contexts of use. A number of choices and problems that standard writers have to face are mentioned. Should a visual display standard be written primarily for young users, with mostly a high visual acuity and in possession of their full accommodative power, wanting to use tiny hand-held displays featuring very small characters ? Or should the standard be focused on the elderly, with their reduction in visual faculties, barring the use of small characters that may irritate or disable such older users ? The question how to put human factors principles in standards sometimes seems a battle between idealists and realists. It therefore is important to strike a balance between different attitudes, backgrounds and interests in a standards writing committee - as indeed happens in ISO/TC 159/SC 4/WG 2, "Visual Display Requirements". The author is convener of this Working Group.
After mentioning the necessity of standardization in general, this paper explains how human factors, or ergonomics standardization by ISO and the deployment of information technology were linked. Visual display standardization is the main topic; the present as well as the future situation in this field are treated, mainly from an ISO viewpoint. Some observations are made about the necessary and interesting co-operation between physicists and psychologists, of different nationality, who both may be employed by either private enterprise or governmental institutions, in determining visual display requirements. The display standard that is to succeed the present ISO standards in this area: ISO 9241-3, -7, -8 and ISO 13406-1, -2, will have a scope that is not restricted to office tasks. This means a large extension of the contexts for which display requirements have to be investigated and specified especially if mobile use of displays, under outdoor lighting conditions, is included. The new standard will be structured in such a way that it is better accessible than the present ones for different categories of standards users. The subject color in the new standard is elaborated here. A number of questions are asked as to which requirements on color rendering should be made, taking new research results into account, and how far the new standard should go in making recommendations to the display user.
SC899: Visual Ergonomics and Aesthetics in Electronic Imaging
Starting from the observation that the use of space, color and typography in text and images as can be seen on the web, on TV, in videotex (in Europe), at conference presentations, and in printed matter often is far from optimal, the course aims at giving writers and editors of such material sufficient knowledge to avoid large errors that will impede legibility and visibility on these text and image-rendering media. Moreover, three different causes for these errors will be uncovered.
The course will focus on giving and explaining rules for:
(1) the legibility of text as a function of characteristics including font type and size, foreground and background luminance and color, the role and value of luminance and color contrast, and layout factors;
(2) legibility and meaning of icons/ symbols/ pictograms as a function of size and internal structure;
(3) the role of text color in association with parts of text with the same color by perceptual grouping, accentuation of small parts of the text with a color differing from that of the surrounding text, categorization of parts of the text by coding them with differing colors, and facilitation or inhibition of reading through the generated impression of orderliness or chaos by the amount and distribution of different colors on the display;
(4) planned and unforeseen special effects of color, such as color stereoscopy;
(5) interaction of spatial, typographical and color effects whereby one or more of the just described effects may be counteracted; and
(6) the 'bipolarity' of utility and attractiveness in a number of cases, such as color in reading; structured vs. 'plain' backgrounds for text; matte vs. glossy display screens and -bezels; and transparency vs. 'prettiness' of screen- and magazine pages.
Examples of these cases will be given, featuring 'good' and 'bad' ones.