When we have to guard a large space, we need to provide ourselves with a good security system. We have already said in previous posts that video surveillance cameras are the central axis of any security installation. They are the eyes that monitor and control every corner of our facilities, and those that allow us to detect intrusions and other dangers. With the cameras we know what is happening. But the cameras must have the latest technological advances. In this post we explain what WDR is, one of the most interesting technologies that we will find in the best video surveillance cameras.
What is WDR?
WDR is the acronym for Wide Dynamic Range. It is a technology that some video cameras have and that serves to compensate for problems with exposure to light. With WDR technology, the camera compensates for images where there are dark and bright areas, in which there is a great decompensation and we cannot see sharp images if we use a normal camera. With this technology, a balance between brightness and darkness is achieved, notably improving image quality and obtaining a more uniform result, thanks to this dynamic treatment of light.
An example of the use of this technology is found in the following situation. When a camera is directed towards a window, we can find areas in which more or less light enters. With a normal camera, without WDR, we will see a part of the image very dark and another very bright, with which many details will be lost. This can be a security breach, since we can lose part of what happens in that darker area. With WDR technology a balance is achieved and we see the entire area of that window with a uniform light level, without loss of detail.
How does the WDR work?
With WDR technology, the camera lens uses different shutter speeds to allow more light in some areas of the image and less light in others, those that are brighter. The sensor’s exposure to light it receives from outside is controlled to achieve a compensated image.
In lighter areas, a higher speed is used so the sensor is exposed to light for less time.
In darker areas, the shutter speed is slower, causing the sensor to capture more light for a longer time.
Both images are combined to obtain a final image with intermediate lighting.
If we have a camera that is monitoring from inside a building through a window, the areas further away from the glass will appear lighter, while those that are closer will appear darker. With double exposure, thanks to WDR technology, we will achieve a sharp and balanced image in which all the space will appear with the same level of illumination.
Cameras with WDR are ideal in different situations that require very high quality monitoring. Some examples can be:
When the camera points from inside a building to the outside (driveways, patio, street). Here, we will find areas of dark light, light changes due to the movement of the sun, etc.
When the camera has to see through glass doors or windows where there are usually many reflections that prevent uniform illumination of the scene.
WDR cameras can be an ideal solution to avoid security breaches that occur in those areas with difficult lighting. Having dark areas mixed with very light areas makes conventional cameras ineffective. Here, it is necessary to make a replacement of cameras if they have not been planned from the beginning. This reinforces the principle of the importance of security system maintenance: if we do not have a maintained and updated security system, we will not have 100% security. In many places, these security cameras do not exist for the simple reason that when the installation was designed they were not yet available. Therefore, we have to have a specialized maintenance that updates our security equipment.
True WDR cameras and WDR Digital (DWDR) cameras
When choosing our surveillance cameras with WDR technology, we have to be careful. Apart from the typical differences between brands and models, we will find two cameras that, although they may seem the same, are not: cameras with TRUE WDR technology and WDR DIGITAL.
True WDRs use the technique of combining different shutter speeds, while Digital WDRs work using a software compensation technique.
Cameras with true WDR (or true WDR) capture two images with different light exposures and merge them into a third image, compensating for light intensities to achieve an optimal overall illumination result. This natural process is replaced by computer compensation in digital WDRs. Here, a single image is made that is digitally and automatically retouched.
Cameras with true WDR capture 60 frames per second to achieve that end result. To do this, they require a greater capacity for image processing. For this reason, True WDR cameras, although more expensive, achieve better results.
This is one of the questions to ask your security installer when designing the video surveillance installation: what type of WDR camera are we going to buy?