Anti-Glare Coating (AG)
The most common type of protective coating is ‘Anti-Glare’ (AG). This is often
described as a matte coating as it is non-reflective to the user since it
diffuses rather than reflects ambient light. It provides a method for
manufacturers to avoid glare on the viewing surface from other light sources and
has been used in the LCD monitor market for many years since the first TFT
displays started to emerge.
This matte coating is included as an outer polarizing later which has been
coarsened by mechanical or chemical processes. This achieves a surface coating
which is not smooth and so can diffuse ambient light rather than reflect it.
What is particularly important to understand is that this AG coating can be
applied to panels with varying thicknesses, which has an impact on the
anti-glare properties, but also on the underlying image of the screen. Where the
coating is particularly thick and aggressive, the image from the screen can
deteriorate as the light being emitted is also affected. This can have some
impact on contrast and colour vibrancy and the perceived image can sometimes
look dull as a result. Sharpness degradation can also occur in some extreme
cases where AG coating is too thick. Users may also sometimes see the graininess
of the coating, particularly when viewing white or light backgrounds. This can
be particularly distracting for office work and images can look grainy or dirty
if the coating is too aggressive. I would point out that not everyone would even
notice this at all, and many users are perfectly happy with their screens even
where aggressive AG is used. It’s just something to be wary of in case you have
found problems with image quality in the past or are susceptible to it.
In other cases, AG coating is applied but it is light and far less obtrusive.
The polarizer is less rough and has a lower haze value. Sometimes users refer to
it as “semi-gloss” to distinguish the difference between these and the heavy AG
coatings. This provides anti-glare properties but does not result in the grainy
appearance of images. It is not a fully glossy solution though.
AG coating has long been the choice for nearly all professional-grade displays
as well, helping to avoid issues with reflections and external light sources
which are vital for colour critical work. In addition it should be noted that AG
coating is less susceptible to dust, grease and dirt marks which can become an
issue on reflective glossy coating alternatives.
of cre3d's AG removal guide,
Some users have even taken matters into their own
hands and removed the AG coating from their screens to produce a glossy surface.
This will of course void your warranty and should be done with caution and
entirely at the users risk. We mention it here as the above images are a good
demonstration of the aggressive coating applied to the screen in some cases. You
can see from the top picture the film being peeled off to leave a glossy
reflective surface underneath. The second image is of course exaggerated quite a
lot but you can see how the image is affected when the photograph is taken with
the AG coating in front, on the right hand side. Of course this is far less
obvious when the coating is in contact with the surface of the screen but it's a
fairly good demonstration of the coating being used in some cases (note, these
were taken from an LG.Display IPS panel on the Dell U2312HM).
It is important to realise
that different manufacturers tend to use different levels of AG coating, often
linked to the panel technology they are developing. See our
following sections for more
information about specific panel manufacturers and technologies.
As an alternative some manufacturers choose to supply their screens with a
glossy screen surface. This gives somewhat of a “wow factor” when you first see
the screen and has often been used by manufacturers like Apple for their screens
and tablets. The glossy panel coating is sometimes combined with a glass
protective layer to give a hard exterior surface to the display and to emphasise
that overall glossy appearance.
Glossy coatings provide very clear, clean and crisp images, free from any form
of graininess or dirtiness you might see from AG alternatives. Images can look
and feel nicer in some cases, often helping colours and blacks “pop” in
practice. However, they aren’t without their own problems as the glossy coating
can cause a lot of unwanted reflections in certain conditions. You have to be
very careful of your ambient lighting conditions and the position of lamps and
windows near your screen. Finger prints, dust and dirt can also become an issue
and are more noticeable on shiny, reflective, glossy surfaces. In some instances
chemical coatings are applied to help try and reduce some of the ambient light
reflections but in reality they still remain reflective in practice and very
different to AG coatings. Glossy screens aren’t for everyone at all, and it
would be advisable to try and see one in person in a shop before making a
purchase if you can.
Where glass coatings are applied as an additional protective layer buyers should
also be aware that there is sometimes the risk of trapped dust or particles
behind the glass which can become an annoyance over time. Some screens are
completely free from this, but it’s just something to be aware of (e.g. dust
issues were found on some
Hazro’s HZ27WA/C/D screens where glass layers were used). Glass layers are
also often provided on touch-screen displays for that added level of protection.
Above: photo of
a glossy apple display showing reflective properties
Glossy screen coatings have been offered over the years in several forms
including older models featuring
Acer CrystalBrite and
NEC OptiClear technologies. Apple have used glossy coatings on their Cinema
Displays for many years and in fact a lot of the modern glossy offerings are
based on IPS panels. More recently other manufacturers like Hazro (HZ27WA/C/D)
and DGM (IPS-2701WPH)
have produced screens based on the 27” glossy IPS panels available. Samsung have
also released their first glossy PLS panel in the
Panel Manufacturer Trends
As we've already mentioned, the
type of coating applied to a panel is very dependent on the manufacturer and the
technology being used. Trends have emerged over the years and here is a summary
of the typical coating usage from different panel solutions:
LG.Display IPS – These
panels are often criticised for their aggressive AG coating. Where AG is used
it is normally very aggressive and some people find the images are too grainy
or dirty looking. As an example the Dell UltraSharp series (U2410, U2412M,
U2711, U3011) are all using aggressive AG coating on their IPS panels. Some
IPS panels are provided with a glossy screen coating as an alternative which
avoids issues with grainy coating, but can result in distracting reflections.
AU Optronics AMVA –
Modern versions of these panels are provided with a light AG coating which is
sometimes referred to as semi-gloss. It is not overly grainy or obtrusive.
Samsung PVA – Samsung
PVA variants are also provided typically with a light AG coating which is not
Samsung PLS – early
versions of the panels were provided with a light AG coating, similar to that
of AMVA panels although not quite as low haze. It was not overly grainy or
distracting. More recently PLS panels have also been supplied with a glass
glossy coating. The technology is in its infancy and so it is hard to
establish a future trend.
TN Film panels – these
are nearly always provided with AG coating although some glossy models have
been produced from time to time. Coating tends to vary but is normally
considered to be ‘medium’ in terms of its aggressiveness. Not as aggressive as
the IPS panels, but not “semi-gloss” like AMVA offerings.
photos courtesy of
Above is a comparison of macro images taken of
varying panel types. This was designed to capture the structure of the panel at
a pixel level but can also be used to demonstrate the coating type being used
and the resulting image clarity. You will see that the aggressive AG coating of
the IPS panels leads to a blurry and grainy image, but the glossy equivalent
leaves a clear and crisp view of the underlying pixels. TN Film is a medium AG
coating and while not as aggressive as the IPS AG coating, it can lead to
noticeable graininess in some cases. AMVA has a light AG coating and as you can
see does not deteriorate the image quality too much.
This hopefully gives you a
summary of the common types of coating used on the main panel technologies in
the market. Of course there are always variations and so we will try to discuss
the coatings in our reviews so you have an idea.
As a final thought I would like to reiterate the
point that not everyone is bothered by the screen coating being used on their
displays. This article is not designed to scare or concern people, just provide
a reference point and information to help buyers make an informed decision. AG
coating has been the main choice for many years now and continues to be popular
with some manufacturers. While some people might be put off by the grainy
coating, others may not even notice it. Glossy solutions also have their pros
and cons and so it's important to try and see screens in person if you can if
you worry you may be affected by any of the characteristics described here.