Wide dynamic range technology
August 11, 2021
wide dynamic range
What is wide dynamic？
When high-brightness areas illuminated by strong light sources (daylight, lamps or reflections, etc.) and low-brightness areas such as shadows and backlighting coexist in the image, the image output by the camera will appear bright areas that become white due to overexposure. The dark area becomes black due to underexposure, which seriously affects the image quality.
The camera has limitations in the performance of the brightest and darker areas in the same scene. This limitation is commonly referred to as "dynamic range".
In a broad sense, "dynamic range" refers to the span of a changing thing that may change, that is, the area between the lowest point and the highest point of its change value. The description of this area is generally between the highest point and the lowest point. Difference.
This is a very widely used concept. When talking about the shooting image index of camera products, the general "dynamic range" refers to the ability of the camera to adapt to the light reflection of the scene in the shooting scene, specifically the brightness (contrast) and color temperature (contrast) ) The range of change.
The wide dynamic camera is dozens of times more than the traditional camera with only 3:1 dynamic range.Natural light is arranged from 120,000 Lux to 0.00035 Lux in the starry night. When the camera looks out of the window from indoors, the indoor illuminance is 100 Lux, while the illuminance of the outside scenery may be 10,000 Lux, and the contrast is 10,000/100=100:1.This contrast makes it easy for the human eye to see because the human eye can handle a contrast ratio of 1000:1.Wide dynamic is a very practical technology, which shortens the distance between the camera and the human eye (making the camera's processing and display of the picture closer to the degree of recognition of the human eye), giving users a more humane experience.
WDR vs DWDR
Users often confuse wide dynamics with digital wide dynamics (DWDR).Digital wide dynamic is the easiest technology in wide dynamic technology.The true wide dynamic can ensure that clear images can be taken in most strong light or backlight monitoring environments. It is possible that digital wide dynamic can only solve some of the picture problems, but not all of them.
Real wide dynamic uses a combination of software and hardware. First, a real wide dynamic camera must use a CMOS image sensor with bandwidth dynamic function, and secondly, it needs the cooperation of a digital image processor.For example, multiple exposure wide dynamic (also called multi-frame imaging wide dynamic) is to use the image sensor to expose the image multiple times (3 or 4 times), and then send it to the image processor for wide dynamic calculation and output a bright and balanced image.
For specific surveillance applications, wide dynamic technology has become a standard feature of high-definition surveillance cameras, and the market is huge.Therefore, Sony newly launched DOL WDR technology last year. The full English name of DOL WDR is Digital overlay wide dynamic range, which is digital overlay wide dynamic range technology.It also uses multiple exposure technology, but DOL WDR can provide better wide dynamic performance in low-light environments.Sony has launched IMX224 (1.2 million pixels), IMX290 (2.1 million pixels), IMX123 (3.2 million pixels) and many other high-definition CMOS image sensors dedicated to video surveillance applications and supporting DOL WDR functions.