Color matching, white balance

White is a mixture of red, green and blue colors according to the brightness ratio. When the brightness of green in the light is 60%, the brightness of red is 30%, and the brightness of blue is 10%, the human eye feels pure white after mixing the colors, but The chromaticity coordinates of the three colors of LED red, green and blue cannot achieve the effect of the full spectrum due to process and other reasons. Controlling the brightness of the primary colors including the biased primary colors to obtain white light is called color matching. Before color matching for a full-color LED display , in order to achieve the best brightness and the lowest cost, you should try to choose LED devices whose luminous intensity of the three primary colors is roughly 3:6:1 to form pixels. The white balance requires that the three primary colors synthesized under the same gray value are still pure. white.

Resolution

Resolution (resolu called interpretability in Hong Kong and Taiwan): It is the precision of the screen image, which refers to the number of pixels that the display screen can display. Since the points, lines and surfaces on the screen are all composed of pixels, The more pixels the display can display, the finer the picture, and the more information can be displayed in the same screen area, so resolution is a very important performance indicator. Pixel (Pixel): the minimum luminescence of the LED display Pixels have the same meaning as "pixels" in ordinary computer monitors.

Brightness

Brightness refers to the brightness of the screen. The unit is candelas per square meter (d/m2) or nit. Simply put, it is the light intensity emitted by one square meter of display screen.

There are 4 commonly used physical quantities of light, they are:

1. Luminous intensity is the luminous intensity of a light source in a given direction. The unit is candela, dela, referred to as can, cd.

2. Luminous flux, the amount of light emitted by a light source per unit time is called the luminous flux of the light source, unit lumen, 1m

3. Illumination, the illumination produced by the luminous flux of 1m (lumen) evenly distributed on the surface of 1m2, unit lux, 1x.

4. Brightness, unit light source area in the normal direction, light flow emitted within unit solid angle, unit nits, n11. It should be noted that brighter products may not necessarily be better products. The display screen is too bright. It often makes people feel uncomfortable. On the one hand, it easily causes visual fatigue. At the same time, it also reduces the contrast between pure black and pure white, affecting the performance of color and gray scales. Therefore, while increasing the brightness of the display, it is also necessary to increase its contrast, otherwise it will The entire display screen will appear white. In addition, the uniformity of brightness is also very important. The brightness of the screen is uniform, soft, and has no obvious dark areas. Maximum brightness of the display: Under a certain ambient illumination, the primary color of the LED display is at the maximum Brightness and brightness at maximum gray level.

Contrast

Contrast refers to the ratio between the brightest and darkest areas of the projected image. The greater the ratio, the more gradient levels from black to white, resulting in richer color performance. Contrast has a very critical impact on visual effects. Generally speaking, It is said that the greater the contrast, the clearer and eye-catching the image will be, and the more vivid and gorgeous the colors will be; while a small contrast will make the entire image gray. High contrast will be of great help to the clarity, detail expression, and grayscale level expression of the image. , the higher the contrast, the better the image effect will be, and the colors will be more saturated. On the contrary, if the contrast is low, the picture will appear blurry and the colors will not be vivid.

Contrast refers to the measurement of different brightness levels between the brightest white and the darkest black in the light and dark areas of an image. The larger the difference range, the greater the contrast. The smaller the difference range, the smaller the contrast. A good contrast ratio is 120. :1 can easily display vivid and rich colors. When the contrast ratio is as high as 300:1, it can support various levels of color. However, the contrast ratio suffers from the same dilemma as brightness. There is currently no set of effective and fair standards. Measure contrast ratio, so the best way to identify is to rely on the user’s eyes

Grayscale

Grayscale is the so-called color scale or grayscale, which refers to the degree of lightness and darkness of brightness. For digital display technology, grayscale is the determining factor in the number of displayed colors. Generally speaking, the higher the grayscale, the richer the colors displayed. The picture is also more delicate, and it is easier to express rich details. Our company's display uses a 16-bit processing system, that is, 65536 levels of gray, and the three primary colors of RGB can constitute 655365536*65536 colors.

Refresh Frequency

The refresh frequency of the display screen is the number of times the display screen is repeatedly displayed by the display screen, and the unit is Hertz (Hz). The higher the refresh frequency, the smaller the flicker of the image on the screen and the higher the stability. In other words, the better the protection of eyesight. Normally, it is not easy for the human eye to detect the flicker caused by a refresh frequency of 75Hz or above. Our company can increase the display frequency to a maximum of 4800HZ, so that the background effect of TV recording can completely get rid of the troubles of water ripples, mosaics, etc., giving people The vision is fresh, comfortable and translucent, and can be used for live broadcasts

Display Color number

Refers to the number of colors that the display screen can display. The more colors displayed, the more delicate and soft the image will be. If each of the three colors red, green, and blue can display 65536 colors, then the three colors can display 65536*65536*65536 colors.

Color Temperature

Color temperature: The most common indicator of the spectral quality of a light source. Color temperature is defined according to an absolute black body. When the radiation of a light source is exactly the same as the radiation of an absolute black body in the visible region, the temperature of the black body at this time is called the color temperature of the light source. The characteristic of the color temperature light source is that in the energy distribution, there is relatively more red radiation, which is usually called "warm light"; after the color temperature is increased, the proportion of blue radiation in the energy distribution increases, which is usually called "cold light". The color temperature of our display screen Adjustable in 35009000.

Uniform Color

Sexual color uniformity generally refers to the consistency of brightness and chromaticity of various parts of the display screen. The quality of color uniformity has a great relationship with the display effect of the display screen.

The inconsistency in brightness and chromaticity of LED affects the display effect of electronic display screens, resulting in undesirable display effects such as blurry screen and mosaic. Since the chromaticity of LED will change significantly with the change of current, PWM pulse width modulation is generally used. Adjust LED brightness. The chromaticity and brightness correction of a pixel is achieved by adjusting the red, green and blue components of the point respectively. For each pixel that needs to be corrected, a 3*3 correction coefficient matrix is needed to multiply it, and the corresponding correction coefficient is passed. The pulse width is used to drive the LED, so that the brightness and chromaticity of the entire display screen are highly consistent. Correction technology has evolved from simple light intensity correction to light intensity + color coordinate correction. The difference in brightness and chromaticity between our display modules can be less than 5%.

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