Brightness refers toIlluminantThe ratio of light intensity to light source area is defined as the brightness of the light source unit, that is, unitProjected areaOnLuminous intensity(Brightness=light intensity ÷ area).The unit of brightness isCandela/Square meter (cd/mtwo）。AndIlluminanceDifferent, the objective corresponding quantity defined by physics islight intensity。These two quantities are often confused in general everyday language.Brightness is also called brightnessLightness, indicating the brightness of the color.The brightness felt by the human eye is determined by the brightness reflected or transmitted by the color.[1]
BrightnessLuminance。A numerical value indicating the brightness of the surface of the light source or the object receiving light.A unit equal to leaving, reaching, or passing through a surfaceSolid angle, on unit projected areaLuminous flux。[2]
Chinese name
brightness
Foreign name
Luminance
Properties
A property of color
Represent
Physical quantity of luminous intensity on the surface of illuminant
θ: Given direction and unit area element dsnormalIncluded angle of direction
Luminance is a property of color, or is related to how bright the color isColor spaceA dimension of.stayLabIn color space, brightness is defined to reflect human's subjective sense of brightness.
Brightness refers to the brightness of the picture, in candela per square meter (cd/mtwo）Or nits, which is candlelight per square meter.At present, there are two ways to improve the brightness of the display screen. One is to improve the brightness of the display screenLCDLight of panelPassing rate；The other is to increase the brightness of the background light.
It should be noted that brighter products are not necessarily better products, and too bright display images often make people feel uncomfortable, which is easy to causeVisual fatigueAt the same time, it also reduces the contrast between pure black and pure whiteColor scaleandGray scalePerformance.Therefore, it is necessary to improve the brightness of the displaycontrast ratioOtherwise, the whole display screen will turn white.In addition to brightnessUniformityIt is also very important, but inLiquid crystal displayProduct specificationThere is usually no marking in the instructions.Whether the brightness is uniform, andBacklightAndreflectorThe quantity of is closely related to the configuration mode. The display with better quality has uniform brightness, soft and unobtrusive, and no obvious dark area.
Now inLCDLuminancetechnical study At present, it has reached 800 or higher, and is close toCRT displayLeveling.in additionLiquid crystal displayThere are different nominal methods for the brightness of. For example, the typical brightness is 350, and the maximum brightness may be 400. The manufacturer generally does not specify the specific type.Therefore, in a certain range, it is not possible to distinguish between good and bad displays only by parameters. When purchasing LCD displays, you should also consider the contrast and other factors comprehensively, and it is best to actually watch the display effect.
The hottestLED backlightThe introduction of technology has a huge impact on displays.LEDThe backlight display improves the brightness of the display by highlighting the LED.First tier domestic brands such asASUS、Samsung、LGThey have already started to use LED as the preferred backlight for some major products.Of course, these big brand displaysProduct qualityBetter, so the display will not "dazzle" because of the increase in brightness, which is not much related to LED backlight technology, so consumers need not be too superstitious that LED backlight can bring a qualitative improvement to the display effect of the display.
Brightness of stars
About 2000 years ago,GreeceastronomerHipparchus A new method for measuring star“the magnitude”Method.He divided the brightness of stars into six grades.The brightness of each star is two and a half times that of the next level, so the first class star is about 100 times brighter than the sixth class star.
Human eye sensation
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According to human eye mechanism and human visual modelSubjective brightnessIt is not exactly the same as the actual objective brightness, but there is a certain correspondence.What the human eye can feelBrightness range(called visual range) extremely wide, from a few tenths of a thousand nits to millions of nits.The reason why it is so wide is that it depends on the regulation of pupils and photosensitive cells.The pupil adjusts its size according to the intensity of external light, so thatretinaOnLuminous fluxTry to be moderate.Under strong light and weak lightCone cellThe sensitivity of the latter is 10000 times that of the former.Under different luminance environments, the human eye producesRelative brightnessIt feels different.For example, for the same electric light, its relative brightness perception to the human eye is different during the day and night.In addition, when the human eye adapts to a certain ambient brightness, the sensing range will become smaller.For example, when the ambient brightness is 10000 t in the daytime, the brightness that the human eye can distinguish is about 200~20000 nits, and the brightness below 200 nits is black.When the nighttime environment is 30 nits, the distinguishable brightness range is 1~200NiteAt this time, the brightness of 100 nits causes a very bright feeling.Only the brightness below 1 nit can cause the black feeling.
The brightness perceived by the human eye andlight intensityIt is exponential, while the brightness defined by physics is proportional to the light intensity.
The brightness of the display is defined as the brightness value in full white color.In fact, people do not need such high brightness in their daily use. High brightness will cause harm to the eyes instead.In most displays, the factory setting is basically 100% brightness, because higher brightness will make users feel better about the intuitive picture. However, excessive brightness for a long time will cause great visual damage.
The authoritative statement is that the brightness is between 120 cd/mtwoTo 150cd/mtwoBetween health and visual effects can get a compromise.Famous brands of major displays in the market, such asASUS、Samsung、LG、AOCWait, the brightness of their mainstream 19 and 22 inch displaysnominalMost of them are 300cd/mtwo, larger dimensions have higher brightness.For example, ASUSLiquid crystal displayThe display below 24 inches is basically 300 cd/mtwoThe brightness of a 27 inch display such as ASUS MT276H reaches 400cd/mtwoTherefore, when paying attention to the brightness parameters of the display, consumers should also consider whether they will use such high brightness.
physical quantity
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Luminous intensity
For a light source in a given directionLuminous intensity, unit: candela, namelyCandela, referred to as Kan and CD for short. Some people still use candlelight to express luminous intensity, which is too old. It was adopted in 1940 (1948)New candlelightIt's just a candle.Candlelight was abolished after 1968.
The unit light source area is in the normal direction, and the unit solid angleOptical flow, in nits, nt
Generally, flashlights and LEDs are measured by luminous intensity, but early LEDs have low "brightness", so they are measured by millicds, that ismcdLater, thousands or tens of thousands of mcd came out, and the unit did not change, so 1000 mcd=1 cd.
