Tuesday, March 3, 2015

AMOLED screen brightness measurements is still a lack of standards

With smart phones increasingly high pixel screen, the screen resolution has been unable to identify the product as a consumer good or bad based on, and is expected to replace the screen brightness will become the reference when consumers buy. However, the current AMOLED screen brightness measurements still not certain standard, also cause difficulties on the appraisal.

According to technology website ExtremeTech reports, Samsung Electronics (Samsung Electronics) of the Galaxy S5 will be with excellent screen brightness based play content; LG Electronics (LG Electronics) launched the G3 brightness due to too low to get Comments favor.

Brightness measurement is better resolution measurements easy. LCD screen brightness measurements on relatively no doubt, mainly because of the penetration of LED backlight LCD screen rely on liquid crystal array presents a variety of colors. The LED light source itself will have a maximum brightness, and the user can see the amount of light is determined by the size and the number of pixels of.

Often used in high-end smart phones AMOLED screen, the brightness measurement standard is still no agreement. Also Nexus 6 screens, magazines measured by Anandtech maximum screen brightness of 258 nits (nit), and the results compared with others measuring 400 nits.

Each sub-pixel AMOLED screen (subpixel) can produce photons (photon), through voltage showing red, blue, green and other colors. If AMOLED pixel closed, it will appear black, this way also reduces the power consumption of the screen.

The LCD screen is different, a AMOLED pixel and no so-called maximum brightness. There are an average AMOLED screen brightness (Average Pixel Level; APL) is called the value, as a percentage of the number of pixels rendered luminous. Black screen APL is 0%, 100% all white, red, green and blue color was 33%. When less luminous pixels, which is a low APL, each pixel will be assigned to a higher power, high brightness light-emitting region representative.

When the APL is 30%, Nexus 6 screen can output more than 400 nits of brightness, but when the APL is 100% all white screen, the light output will be reduced to about 250 nits. It can be seen, Anandtech magazine test using APL is 100% all white screen, resulting in the measurement results are significant differences with others.

ExtremeTech reports that, in actual use, the majority of the screen has a very high APL, especially the Android 5.0 user interface will use a lot of white elements, APL its setting screen can be as high as 84%. It seems that the maximum brightness at very low APL achieved is not entirely reliable, so the actual maximum Nexus 6 screen brightness should be between 258 and 400 nits between nits.

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