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Why 4K HDR cameras with large pixel size for outdoor vision applications

Why 4K HDR cameras with large pixel size for outdoor vision applications?

Published on September 1, 2021

Imagine a traffic control system that collects and analyses information of vehicles in a wide area, performs the optimal traffic signal control in accordance with the constantly changing traffic, and provides useful traffic insights to drivers based on the data collected.

Or a patrol robot that performs intelligent video surveillance to prevent unlawful activity and thwart intrusions into areas with restricted access. Or simply an agricultural vehicle equipped with cameras to detect crops and obstacles while plowing, watering, spreading fertilizer, and planting.

In all these applications, imaging is crucial yet challenging. Each of these outdoor applications needs to capture a wide area with greater details. These outdoor applications also require reproducing the exact scene even in challenging outdoor lighting conditions.

To cover a wide area with the potential to zoom in on images without losing image quality and to perform well in contrast lighting conditions, a camera with 4K, large pixel size, and HDR capabilities is required. This article is intended to shed some light on these features, and how cameras with these capabilities could be a perfect solution for outdoor applications.

Why 4K resolution?

As mentioned before, most of the outdoor applications such as smart traffic management, outdoor surveillance, and outdoor robots require cameras to cover a large area. Even with a wide Field Of View (FOV), cameras will be unable to capture the required details without adequate resolution. By selecting a high resolution camera with more number of pixels, pixel density will increase resulting in an image output with more details of the target scene.  

Now, what is the ideal resolution to go for in such scenarios?

Full HD (1080p) is not seen as high resolution anymore. Full HD images while zoomed in cannot offer the details and quality required for many outdoor applications. At the same time, a 4K image has four times the number of pixels as compared to a 1080p image, and offers the ability to cover a wider Field Of View (FOV) owing to the increased number of pixels that constitute an image output. Hence, a 4K camera is always preferred over a Full HD camera for outdoor applications, especially when a wide field of view needs to be covered.

Why large pixel size and large sensor?

A sensor with large pixel size has the ability to absorb more number of photons making it effective in capturing images in low light conditions. This is helpful in outdoor applications that need low light performance such as a patrol robot which has to do outdoor patrolling even during the night.

Also, sensor size and resolution are interrelated. Larger the sensor, higher will be the number of pixels, and better will be the resolution. So a 4K resolution with large pixel size would mean that the sensor is also relatively larger in size.

A large sensor helps to cover a wide FOV in two different ways. Firstly, since a large sensor is likely to have high resolution, zooming becomes more effective with large number of pixels. Secondly, only if the sensor is of adequate size, it will be able to accommodate all the photons that come through a wide FOV lens.

Both large pixel size and sensor size are critical camera features for outdoor applications. However, as explained above, both have to be understood differently and serve two different purposes.

Why High Dynamic Range (HDR)?

We have learnt the importance of using a 4K sensor with large pixel size for outdoor applications in the previous sections. Let us now look at why High Dynamic Range (HDR) is critical for outdoor applications.

Consider capturing a vehicle’s license plate in a toll booth. Since the camera is mostly placed under a roof, the scene is likely to have both dark and bright areas. It’s difficult to capture a clear image with such varied light intensities. Once the spectral range in a scene exceeds the camera’s dynamic range, the object captured will tend to wash out to white in the output image. The dark areas in the scene also appear darker.

To avoid this, outdoor cameras need to capture images with optimal exposure time, where the bright areas aren’t too bright, and the dark areas aren’t too dim. This is why HDR is recommended for such use cases. HDR mode captures images and videos without losing details in bright and dark areas of a scene.

An HDR image is usually obtained by capturing three images of the same scene, each at different shutter speeds. The result is a bright, medium, and dark image, depending on the amount of light that got through the lens. The image sensor then combines all the three images to stitch together the entire image. This post-processing activity – that takes place in a dedicated ISP – of taking either one image or a series of images, combining them, and adjusting the contrast ratios with a single aperture and shutter speed produces HDR images.

Conclusion

With the advent of AI based outdoor automation applications, the need for advanced cameras with better image quality has also increased. For a vast majority of outdoor applications, – such as smart traffic, delivery robots, patrol robots, agricultural & heavy vehicles – an imaging system with HDR is required. it is also important to consider a camera with 4K and large pixel size in order to capture high resolution images with necessary details.  

e-con Systems has designed See3CAM_CU81, an 8 MP UVC compliant HDR USB 3.1 Gen 1 camera. This 1/2 inch sensor with a large pixel size is capable of capturing 4K images with great details in all lighting conditions. To learn more, please check our See3CAM_CU81 – 4K HDR USB Camera.

See3CAM_CU81 – 8 MP HDR USB 3.1 Gen 1 Camera:

SensorAR0821 from ON Semiconductor
Focus TypeFixed focus
Sensor Resolution8MP
ChromaColor
Optical Format1/2″ Optical format
Output FormatUncompressed UYVY and Compressed MJPEG
Pixel size2.1 μm x 2.1 μm
InterfaceUSB 3.1 Gen 1 Camera

If you have any further queries about the camera, please feel free to write to us at camerasolutions@e-consystems.com

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