Delivering reliable image data is an important requirement for embedded vision applications. However, lighting conditions in real-world scenes are rarely uniform. For instance, bright streetlamps, headlight glare, tunnel shadows, or mixed indoor lighting can either affect exposure and/or cause unnatural color tones in captured images.
Moreover, fluctuating or varying luminance of the scene could lead to exposure bouncing issues in automotive applications.
e-con Systems’ ISX031-based cameras address these challenges through key light metering features, which are part of their parameter control functions. It can intelligently analyze brightness and color temperature, adjusting the exposure and white balance accordingly. This empowers mobility applications such as delivery robots, autonomous vehicles, mining vehicles, and sports broadcasting applications.
In this blog, let’s explore the two light metering features of the ISX031-based cameras in detail. We’ll learn how each feature functions and understand the scenarios in which and how it delivers precise image data, even in diverse lighting environments
Understanding Light Metering
Light metering is the process of measuring the brightness and color temperature of a scene. That way, the camera automatically adjusts settings for exposure and white balance functions, respectively.
What is AE Light Metering?
AE is a function that controls exposure by calculating the exposure time and gain based on the light metering result of the input image signal to obtain the optimum exposure.
Key features of AE Light Metering
AE Light Metering Window
The AE (Auto Exposure) light metering window defines a specific region—or even the entire frame—within the camera’s field of view that is used to calculate the required exposure value. The size and start position of the AE light metering window are fully customizable. This evaluates the target ROI, allowing improved exposure control in diverse lighting environments.
AE Light Metering Window Mask
The AE light metering window features a masking option, allowing bright sources, like headlights or direct sunlight, to be excluded from exposure calculations. Without masking, these sources could skew exposure levels and cause other parts of the image to appear underexposed.
By masking these regions, the camera can focus on relevant parts of the scene, resulting in better exposure accuracy. Up to five rectangular masking regions can be configured to achieve fine-grained control over the exposure evaluation process.
The image below shows the camera preview with AE light metering window and mask (i.e., blue grid and blue patch).
In the preview, the AE light metering window is set for the camera’s entire FOV, and the bright light source is masked. Though the entire window is selected, masking the bright source ensures that high-intensity areas are excluded from the AE calculation, resulting in a more balanced and accurate exposure.
Vehicles often struggle with light variations caused by uneven lighting and widely spaced streetlights. As the vehicle moves or turns, brightness can shift drastically, from dark shadows to sudden glare in a dark region, affecting image quality.
Watch how the AE Window feature in our ISX031-based camera eliminates exposure fluctuations to deliver crystal-clear images for reliable navigation.
What is AWB Light Metering?
AWB is a function that compensates for the gain value for the R and B signals based on the light metering result of the input image signal, to reproduce achromatic color based on the color temperature of the scene.
Key features of AWB Light Metering
AWB Light Metering Window
The AWB (Auto White Balance) light metering window works similarly to AE light metering but focuses on the color temperature and white balance of the scene. It enables the camera to evaluate a specific region or the full frame for color adjustment, to reproduce achromatic color based on the color temperature of the scene.
The start position and size of the window can be configured based on the Region of Interest (ROI). This helps exclude the impact of the light source with a different color temperature or region of dominant color, which affects the white balance evaluation value.
The camera uses the RGB data of the window to apply appropriate white balance adjustments, based on the desired light source.
AWB Light Metering Window Mask
AWB also includes a masking feature that helps exclude extreme light sources from influencing the white balance calculation. Up to five rectangular masking regions can be configured.
Major Use Case of AWB Window
When two cameras are spaced apart in an autonomous vehicle, having overlapped FOV, the cameras may have slight differences in white balance settling, depending on the environment they cover. To avoid these differences, the AWB metering window can be set in the overlapped areas of both cameras.
In the demonstration below, one camera is mounted on the left side of the vehicle, and the other on the right. The left camera’s Field of View (FOV) captures primarily trees, while the right camera’s FOV includes both trees and sky. The scene variation between the two cameras results in noticeable differences in color and image output.
The influence of the sky can often distort overall color balance in a scene, as shown below. The overall preview appears with a bluish color tone, as shown below.
The camera with AWB window and mask features helps to adjust the region used for white balance evaluation and exclude intense colored light sources. This prevents unnatural color shifts and ensures consistent, accurate color reproduction.
Below are the ISX031-based cameras, supporting AE & AWB light metering window:
e-con Systems Offers Cameras with Configurable AE and AWB Light Metering Window
Since 2003, e-con Systems has been designing, developing, and manufacturing high-performance embedded cameras. Our Sony ISX031-based camera solutions come with customizable AE and AWB light metering functionality, including configurable metering windows, region-based evaluation, and flexible masking options.
We also offer cameras with HDR and LFM support for various lighting conditions, multi-camera synchronization, and custom interfaces. Our solutions integrate premium sensors from Sony, onsemi, and OmniVision, and are compatible with powerful development platforms such as NVIDIA, Qualcomm, and more.
To know more, explore more features, and find the right camera for your project using our Camera Selector Tool
Need integration help or expert advice? Write to camerasolutions@e-consystems.com for customization support from our domain specialists.
Prabu is the Chief Technology Officer and Head of Camera Products at e-con Systems, and comes with a rich experience of more than 15 years in the embedded vision space. He brings to the table a deep knowledge in USB cameras, embedded vision cameras, vision algorithms and FPGAs. He has built 50+ camera solutions spanning various domains such as medical, industrial, agriculture, retail, biometrics, and more. He also comes with expertise in device driver development and BSP development. Currently, Prabu’s focus is to build smart camera solutions that power new age AI based applications.