|1. What is grey level?|
Grey level: A calibrated sequence of grey tones, ranging from black to white. In remote sensing, electromagnetic radiation falling on a photosensitive receiver generates an electrical current proportional to the intensity of the radiation. The receiver is usually tuned to specific wavelength bands and the signal from each receiver is amplified and its intensity classified into different levels, usually 0 (black) to 256. These are the digital numbers of each of the pixel units that together make up a remotely sensed frame. In multi-spectral scanning systems, the digital numbers are classified into grey-scale bands, of which there are usually 10 to 12, but up to 256 shades of grey (brightness) may be used.
|2. The explanation of Ingress Protection (e.g.IP65)|
Ingress Protection (IP) is a European rating that describes the degree of protection provided by an enclosure of electrical equipment. The rating system consists of the letters IP followed by two numbers:
The first number indicates the degree of protection against solid foreign object ingress.
The second number indicates the degree of protection against liquid ingress.
According to this system an IP65 enclosure will not allow the ingress of dust and is protected against jets of water from any direction. IP65 enclosures are ideal therefore for use in wet and wash-down environments for example food preparation areas.
|3. What are refresh rate and frame rate?|
The refresh rate is the number of times a display’s image is repainted or refreshed per second. As it denotes a frequency of a process, the refresh rate is expressed in hertz. That is, a refresh rate of 75 Hz means the image is refreshed 75 times in one second.
Frame rate, or frame frequency, is the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems. Frame rate is most often expressed in frames per second (FPS), and is also expressed in progressive scan monitors as hertz (Hz).
|4. What is viewing angle?|
Viewing angle is the maximum angle at which a display can be viewed with acceptable visual performance. It includes horizontal viewing angle and vertical viewing angle.
|5. Drive Method, driving IC and Power supply|
Drive Method: always we use static, 1/4 scan, 1/8 scan, 1/16 scan, the latter one contributes to less brightness than the former. We always use the static outdoor, and use the different kinds of scan indoor.
Driving IC is the generic term for several kinds of IC, that are used to control the LED lamps, and as a bridge between the control system and lamps.
Power supply: a kind of device that used as a transfer from 220V AC into 5V DC. It always seems like a box in the cabinet.
|6. What are LED Type, module size and module resolution?|
LED Type is the description of LED lamp, for instance, the brand, the shape in physical, the size of the lamp, etc.
Module size is the measurement of a module.
Module resolution is the number of pixels per module.
|7. What are Pixel Pitch, Pixel Density, LED QTY,and Pixel Configuration?|
Pixel Pitch is the distance between neighboring pixels.
Pixel Density is the quantity of pixels per square meter.
LED QTY is the quantity of LED lamps per square.
Pixel Configuration is the description of the consistence of a pixel, for instance, we use 1 red lamp, 1 green lamp, 1 blue lamp to compose a pixel, the pixel configuration is 1R1G1B.
|8. LED Display Contrast|
|Along with proper brightness, a display must have high contrast for good readability. Contrast is the difference between the background’s “off state” (blank display area) versus the “on state” (illuminated display area). High contrast increases the readability of a message, much like white text on a black background, causing readers to focus on what needs to be seen. The highest contrast appears in a display with a dark border and a consistent dark black background across the entire display with minimal sunlight reflection. A louver system provides shading and black, non-reflective materials ensure the least amount of reflection. Polycarbonate or acrylic face material may provide as high a contrast as flat black paint or a black potting encapsulant.|
|9. LED Display Color depth|
"Dimming" and "shading" refer to entirely different functions and the terms should not be interchanged. The word “dimming” refers to a uniform brightness adjustment across the entire display to correct the intensity for ease of reading different ambient light conditions. "Shading" or color depth, affects the light output variations of each individual red, green and blue LED to create images within the display.
Color depth chat
Bits per color Resulting shades per color Resulting RGB color capability
25 * 25 * 25 = 32,768 colors
Calculation explanation: Each individual red, green and blue LED be in one of two states, either on or off. This example uses a color data processing of 5 bits for each color is 2 to the 5th power and multiplying each color’s depth provides the overall color depth of 32,768 colors.
Although "dimming" and "shading" have different meanings, some manufacturers will combine greyscale shading values with dimming values to create a color specification that appears more impressive on paper than it is capable of producing in the field.Combining shading values with overall dimming values is a deceiving and misleading practice. Below is an incorrect calculation that includes dimming as part of the color depth:
25 * 25 * 25*32 dimming = 1 million colors
|10. LED Display Video|
Video can be described as display a moving image, which is made up of many individual frames played at a fast rate. Good video is played at 30 frames per second or higher. Slower rate can begin to look choppy and affect the presentation quality.
Video content can be “live”, such as previously recorded live feeds, or previously created content full-capable video displays as being capable of both live feeds and pre-produced content, whereas graphic messaging displays are only capable of pre-produced, or stored content. Many LED display applications do not require the live feed capability or complexity of these systems. The higher the level of expectation, the higher the required display capability.
Video graphical frames require high pixel counts and color depth to provide good definition for highly detailed, accurate and recognizable images. Video clips can be small displays with minimal color depth, but the image will look pixilated and will lack definition; however, the results may be acceptable for certain applications. Color depth, or levers, is the amount of color available to portray the image. Most digital video content is 16.7 million colors but more levels of color depth are recommended to provide proper color matching to the original image. Video purists suggest a minimum of 1 billion colors for best video images.