What is the ISO 13406-2 standard for LCD screen pixel faults? (Anders Jacobsen's blog)

January 04, 2006

What is the ISO 13406-2 standard for LCD screen pixel faults?

I'm in the market for a new screen to hook up to my cute little sub-notebook laptop.

While browsing, I noticed that all the flat panel monitors for sale at komplett.co.uk are labelled

All LCD displays adhere to the ISO 13406-2 standard with regard to pixel faults.

This, of course, tickled my attention, as my assumption was that by default, if I buy a flat screen monitor, it's without pixel faults ('dead pixels' are dots of the screen that don't display correctly, e.g. a black/mis-coloured dot in a space that's supposed to be white. Very annoying if you end up with a screen that has one).

NEC Display Solutions Sweden tells us the following about ISO 13406-2:

Pixel faults are a weakness typical of LCDs and are subdivided into four classes, 3 types of pixel fault and 2 concentration criteria within the framework of the ISO 13406-2 test. For the different types of pixel fault, a distinction is made between illuminated pixels, dark pixels and sub-pixel failures (or flashing pixels). The concentration criteria distinguish between firstly the number of white or black pixels occurring in a particular area (cluster) and secondly the sub-pixel failures or flashing pixels occurring within a cluster. The four classes of ISO-13406-2 define the maximum number of failures allowed for each type of pixel fault and each of the concentration criteria. Class 2 is typical. Class 1 is intended only for demanding special applications and Class 3 is for inexpensive models. Class 4 represents the reject criteria in manufacture.

The really interesting answer, however, is provided by new-monitors.co.uk: exactly how many pixels must be bad in a new monitor before the manufacturer is likely to give you a new one on the guarantee?

To regulate the acceptability of defects and to protect the end user, ISO have created a standard for manufacturers to follow. ISO 13406-2 recommends how many defaults are acceptable in a display before it should be replaced, within the terms & conditions of warranty.
All reputable manufacturers conform to and support the ISO 13406-2 standard.

The table below shows the allowable number of malfunctioning pixels that are acceptable, depending on the native resolution of the LCD and allowing for 2 malfunctioning pixels per million pixels.

Native resolution No. of pixels No. of million pixels Acceptable defects
1024 x 768 786,432 0.8 2
1280 x 1024 1,310,720 1.3 3
1600 x 1200 1,920,200 1.9 4
2048 x 1536 3,145,728 3.1 6

The table below shows the allowable number of malfunctioning sub-pixels that are acceptable, depending on the native resolution of the LCD and allowing for 5 malfunctioning sub-pixels per million pixels.

Native resolution No. of pixels No. of million pixels Acceptable defects
1024 x768 786,432 0.8 4
1280 x 1024 1,310,720 1.3 7
1600 x 1200 1,920,200 1.9 10
2048 x 1536 3,145,728 3.1 16

The table below shows the allowable number of malfunctioning sub-pixels that are acceptable within a 5 x 5 block of pixels, depending on the native resolution and allowing for 2 malfunctioning sub-pixels within a 5 x 5 block, per million pixels.

Native resolution No. of pixels No. of million pixels Acceptable defects
1024 x 768 786,432 0.8 2
1280 x 1024 1,310,720 1.3 3
1600 x 1200 1,920,200 1.9 4
2048 x 1536 3,145,728 3.1 6

The above is relevant to Class II LCD panels.

Native resolution	No. of pixels	No. of million pixels	Acceptable defects
1024 x 768	786,432	0.8	2
1280 x 1024	1,310,720	1.3	3
1600 x 1200	1,920,200	1.9	4
2048 x 1536	3,145,728	3.1	6