What is WDR & HDR? Do I need it in my Dash Cam?

Let’s say you’re trying to record footage from a camera in a location with strong contrasting lighting, for example, during sunrise or sunset, where the sun is low on the horizon, causing strong backlighting, shadows, and extreme differences in brightness between the bright sky and the darker road. In this case, due to the bright sunlight in the background, your images will be either:

• Bright due to overexposure in the lighter parts of the scene
• Dark due to underexposure in the dark parts, blurring important details

This is because cameras have a limited dynamic range, unlike the human eye, which can adapt to a wide range of lighting levels. However, with Wide Dynamic Range (WDR) and High Dynamic Range (HDR) technology, this can be avoided, and images can be clear, crisp, and balanced.

What is dynamic range?

It is the range of light intensity that a camera’s sensor can capture in a single shot, from the darkest point in a scene to the brightest point, while retaining subtle nuances.

What is dynamic range available in dash cams?

A regular dash cam that uses a regular image sensor has a limited dynamic range, so you either get bright or dark recordings, as the camera lacks the ability to automatically adjust as needed since its dynamic range is limited, it can adjust to either the brightest or darkest points.

When advanced dash cams that use a modern image sensor such as the Sony STARVIS sensor are able to adjust the time required for light to enter (exposure time) and optimize the image according to the brightness of the scene. They shorten the exposure time in a bright scene, and increase the exposure time in a dark scene, to collect enough light to get the best image.

What is wide dynamic range (WDR)?

WDR is the ability of a camera to capture information from both bright and dark parts of a scene. By combining multiple exposures of the same scene, you can get an image with balanced brightness and contrast. This is useful when driving through locations with a lot of shadows, such as tunnels or walkways, because it allows the camera to capture both dark and light areas of the scene at the same time. High dynamic range uses the image sensor and digital signal processor (DSP) to process each video frame twice. The first is captured at a slow shutter speed (to capture more light). The second is captured at a high speed to capture less light. The camera then combines the two to create a single, well-lit, balanced image.

What is High Dynamic Range (HDR)?

Have you ever been in a situation where the headlights of oncoming cars are so bright at night that you can’t open your eyes? Or the license plate in front of you is reflective, and you can’t make out the numbers while the headlights are shining?
In this highlight scene, it’s hard to see clearly. If there’s a traffic accident, and the footage from your dash cam is blurry and unreadable, it’s much less useful. To address this problem, HDR is used in dash cams.
High dynamic range increases the dynamic range of the camera by recording multiple images—one short exposure and one long exposure—and merging them in real time into a single image with the best possible color balance.

Are all cameras with HDR and WDR the same?

HDR is a software solution that can be turned on and off, while WDR is a physical solution built into the image sensor. What you should consider when comparing is the decibels (db), which is the ratio between the brightest and darkest points that the camera can capture. This determines the range in which WDR and HDR operate. The higher the ratio, the better the camera can process the difference between low and high light spectra, and the better your photos will be. The higher the decibel number, the better the camera will perform in low and high light.

Which is better? HDR or WDR?

WDR and HDR are both camera technologies that aim to improve the quality of video recordings, especially in low light conditions. While WDR can help improve image quality in dynamic lighting conditions, HDR can illuminate darker sections of a scene better without overexposing lighter areas. It also doesn’t generate noise or affect image quality, which can happen with some WDR cameras.

Which is better for a dash cam really depends on the camera and the settings that will be used. In general, WDR may be more effective for recording high-contrast scenes, but HDR will be better at capturing a variety of colors throughout the scene.  Therefore, WDR may be better for cellphone and action cameras, and HDR is better for dash cams, helping them capture fine details like license plate numbers and road markings.