ISO 13406-2

ISO 13406-2 is an ISO standard, with the full title "Ergonomic requirements for work with visual displays based on flat panels -- Part 2: Ergonomic requirements for flat panel displays". It is best known to end consumers for defining a series of flat-panel display "classes" with different numbers of permitted defects (or "dead pixels"). ISO 13406-2 also provides a classification of Viewing Direction Range Classes and Reflection Classes.

As part of an ISO standard, the classes are guidelines, and not mandatory. Where implemented, the interpretation of the standard by the panel or end product manufacturer and effects in terms of labeling of products, what class of panel is used, etc., can vary. Most flat-panel makers use this standard as the excuse for not accepting returns of defective flat-panels. Many customers argue that it's not honest in the makers' part to sell a product that most people wouldn't accept if they knew it had these defects. Also, there is little offer of Class I panels, that added to the fact that the price of these models is usually very high, make it difficult to buy a totally guaranteed product. One solution to this problem would be to sell these defected panels at a lower price than normal ones, clearly indicating the presence of such defects.

The ISO 13406-2:2001 standard has been withdrawn and revised by the ISO 9241-302, 303, 305 and 307:2008 standards.

Pixel Fault Classes

The standard lists four classes of devices, where a device of a specified class may contain a certain maximum number of defective pixels. Three distinct types of defective pixels are described:

  • Type 1 = a hot pixel (always on, being colour white)
  • Type 2 = a dead pixel (always off, meaning black)
  • Type 3 = a stuck pixel (one or more sub-pixels (red, blue or green) are always on or always off)

The table below shows the maximum number of allowed defects (per type) per 1 million pixels.

Definition of Pixel Fault Classes – Maximum number of faults per million pixels
Class Type 1 Type 2 Type 3 Cluster with more than one type 1 or type 2 faults Cluster of type 3 faults
I 0 0 0 0 0
II 2 2 5 0 2
III 5 15 50 0 5
IV 50 150 500 5 50

As of 2007, most manufacturers specify their products as Pixel Fault Class II.


  • The importance of international display standards for both customer and user is explained in this paper presented at the SID Conference 2006: International Display Standards: Status & Agenda", SID'06 International Symposium, Session 9: Display-Measurement&Standards.[1]
  • ISO 13406-2:2000 "Ergonomic requirements for work with visual displays based on flat panels -- Part 2: Ergonomic requirements for flat panel displays."
  • ISO 9241-300: "Ergonomics of human-system interaction -- Part 300: Introduction to electronic visual display requirements." The ISO 9241-300 series establishes requirements for the ergonomic design of electronic visual displays. These requirements are stated as performance specifications, aimed at ensuring effective and comfortable viewing conditions for users with normal or adjusted-to-normal eyesight. Test methods and metrology, yielding conformance measurements and criteria, are provided for design evaluation. ISO 9241 is applicable to the visual ergonomics design of electronic visual displays for a diversity of tasks in a wide variety of work environments.
Defective pixel

Defective pixels are pixels on a liquid crystal display (LCD) that are not performing as expected. The ISO standard ISO 13406-2 distinguishes between three different types of defective pixels, while hardware companies tend to have further distinguishing types.

Similar defects can also occur in a charge-coupled device (CCD) or CMOS image sensor in digital cameras. In these devices, defective pixels fail to sense light levels correctly, whereas defective pixels in LCDs fail to reproduce light levels correctly.

Electronic visual display

An electronic visual display, informally a screen, is a display device for presentation of images, text, or video transmitted electronically, without producing a permanent record. Electronic visual displays include television sets, computer monitors, and digital signage. By the above definition, an overhead projector (along with screen onto which the text, images, or video is projected) could reasonably be considered an electronic visual display since it is a display device for the presentation of an images, plain text, or video transmitted electronically without producing a permanent record. They are also ubiquitous in mobile computing applications like tablet computers, smartphones, and information appliances.

ISO 9241

ISO 9241 is a multi-part standard from the International Organization for Standardization (ISO) covering ergonomics of human-computer interaction. It is managed by the ISO Technical Committee 159. It was originally titled Ergonomic requirements for office work with visual display terminals (VDTs).

From 2006 on, the standards were retitled to the more generic Ergonomics of Human System Interaction.As part of this change, ISO is renumbering some parts of the standard so that it can cover more topics, e.g. tactile and haptic interaction. For example, two zeros in the number indicate that the document under consideration is a generic or basic standard. Fundamental aspects are regulated in standards ending with one zero. A standard with three digits other than zero in the number regulate specific aspects.

The first part to be renumbered was part 10 (now renumbered to part 110). Part 1 is a general introduction to the rest of the standard. Part 2 addresses task design for working with computer systems. Parts 3–9 deal with physical characteristics of computer equipment. Parts 110 and parts 11–19 deal with usability aspects of software, including Part 110 (a general set of usability heuristics for the design of different types of dialogue) and Part 11 (general guidance on the specification and measurement of usability).

Liquid-crystal display

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals. Liquid crystals do not emit light directly, instead using a backlight or reflector to produce images in color or monochrome. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and seven-segment displays, as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.

LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens are also used on consumer electronics products such as DVD players, video game devices and clocks. LCD screens have replaced heavy, bulky cathode ray tube (CRT) displays in nearly all applications. LCD screens are available in a wider range of screen sizes than CRT and plasma displays, with LCD screens available in sizes ranging from tiny digital watches to very large television receivers. LCDs are slowly being replaced by OLEDs, which can be easily made into different shapes, and have a lower response time, wider color gamut, virtually infinite color contrast and viewing angles, lower weight for a given display size and a slimmer profile (because OLEDs use a single glass or plastic panel whereas LCDs use two glass panels; the thickness of the panels increases with size but the increase is more noticeable on LCDs) and potentially lower power consumption (as the display is only "on" where needed and there is no backlight). OLEDs, however, are more expensive for a given display size due to the very expensive electroluminescent materials or phosphors that they use. Also due to the use of phosphors, OLEDs suffer from screen burn-in and there is currently no way to recycle OLED displays, whereas LCD panels can be recycled, although the technology required to recycle LCDs is not yet widespread. Attempts to increase the lifespan of LCDs are quantum dot displays, which offer similar performance as an OLED display, but the Quantum dot sheet that gives these displays their characteristics can not yet be recycled.

Since LCD screens do not use phosphors, they rarely suffer image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs are, however, susceptible to image persistence. The LCD screen is more energy-efficient and can be disposed of more safely than a CRT can. Its low electrical power consumption enables it to be used in battery-powered electronic equipment more efficiently than CRTs can be. By 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes.

List of International Organization for Standardization standards, 12000-13999

This is a list of published International Organization for Standardization (ISO) standards and other deliverables. For a complete and up-to-date list of all the ISO standards, see the ISO catalogue.The standards are protected by copyright and most of them must be purchased. However, about 300 of the standards produced by ISO and IEC's Joint Technical Committee 1 (JTC1) have been made freely and publicly available.

ISO standards by standard number

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