What you will learn:
- How DOL HDR works with Sony IMX415 and NVIDIA Argus ISP to minimize motion artifacts and enhance dynamic range
- The required devicetree configurations to enable HDR modes on Jetson platforms
- Key differences between SDR and HDR imaging with practical comparisons
- The benefits of DOL HDR for real-world applications such as smart traffic, robotics, surveillance, and industrial inspection
DOL HDR (Digital Overlap HDR, used in Sony sensors and supported in NVIDIA Argus ISP) captures multiple exposures (short, medium, long) in quick succession within the same frame period. Basically, this HDR imaging technique captures scenes across light intensities (very bright and very dark areas) in one image frame. These exposures are digitally overlapped and combined by the ISP or a downstream processing unit to create a final image with enhanced dynamic range.
It reduces motion artifacts compared to conventional multi-frame HDR, which can cause ghosting or misalignment in fast motion.
However, DOL HDR does not fully eliminate motion artifacts. Different exposures are still sampled sequentially (though with small offsets). Hence, fast motion can still cause misalignment or color shading issues (e.g., pinkish tint). That’s why NVIDIA documentation mentions that motion artifacts are a known limitation of DOL HDR.
In this blog, you’ll find out how e-con Systems’ e-CAM80_CUNX, an IMX415-based camera, uses the multi-exposure mode feature to support HDR with NVIDIA’s Argus ISP architecture.
How the HDR Mode Works with NVIDIA’s Platform
The IMX415 sensor supports the multiple exposure HDR function. The camera generates a stream of alternating long exposures and short exposures in a single frame. The gain and exposure are adjusted for each frame separately using their respective sensor configurations in the Digital Overlap HDR function.
In DOL HDR, multiple exposures are transmitted over CSI, followed by the fusion in the NVIDIA ISP.
The sample block diagram below explains the basic HDR workflow.
Devicetree entries
The additional devicetree entries that should be configured to the devicetree are:
/* for HDR modes */
active_w
active_h
num_of_exposure
num_of_ignored_lines
num_of_lines_offset_0
num_of_ignored_pixels
num_of_left_margin_pixels
num_of_right_margin_pixels
min_hdr_ratio
max_hdr_ratio
active_w property defines the width value (Active Width + LI + Left Margin + Right)
active_h property defines the height value (Active Height * 2)
num_of_exposure property defines how many exposures are present per frame when using HDR (High Dynamic Range) modes.
num_of_ignored_lines defines the number of sensor output lines that should be ignored (discarded) by the ISP after each exposure frame, especially during DOL HDR (Digital Overlap HDR) or multi-exposure operations.
num_of_lines_offset_0 property defines how image data from multiple exposures is vertically aligned or separated within the sensor’s frame.
num_of_ignored_pixels property defines the number of pixels at the beginning of each line in the sensor’s output frame that should be discarded or skipped by the ISP during image processing.
num_of_left_margin_pixels defines the number of horizontal pixels (starting from the left edge of the image) that serve as a margin or buffer to align and correctly demultiplex the interleaved HDR exposures (such as short, medium and long exposures) in DOL HDR mode.
num_of_right_margin_pixels property defines the number of horizontal pixels at the right edge of each image row that should be treated as a margin or ignored area.
min_hdr_ratio & max_hdr_ratio properties define the supported range of exposure ratios between long and short exposures in a multi-exposure HDR mode like DOL HDR (Digital Overlap HDR).
The sensor data sheet can be referred to configure the values for these properties to get proper HDR output via the NVIDIA Argus ISP pipeline.
SDR vs. HDR: A Comparative Analysis
Our e-CAM80_CUNX camera is configured to support an additional resolution mode of 3840×2160 @ 12BPP, with multi-exposure settings configured at the sensor level. The NVIDIA Argus ISP has been tuned to enhance low-light noise performance, including adjustments to short noise parameters on the platform side.
The following images illustrate a comparison between SDR and HDR modes using the e-CAM80_CUNX camera, highlighting the HDR capabilities of the IMX415 sensor with the NVIDIA Argus ISP.
| Environment | SDR | HDR |
| Outdoor | ||
| Indoor |
e-con Systems’ IMX415 Camera for NVIDIA® Jetson Xavier™ NX/Nano
Since 2003, e-con Systems has been designing, developing, and manufacturing OEM cameras. This includes those powered by the Sony STARVIS™ IMX415 sensor, such as e-CAM80_CUNX.
This 8MP ultra-lowlight MIPI CSI-2 camera can stream 4K @ 44 fps and be directly connected with the NVIDIA Jetson Xavier™ NX developer kit. It leverages NVIDIA® on-board Jetson Xavier™ NX ISP to perform auto white balance and auto exposure control, producing superior image quality in visible and low-light conditions.
Use our Camera Selector to view our full product portfolio.
If you need help integrating a Sony IMX415 camera into your embedded vision system, please write to camerasolutions@e-consystems.com.
Frequently Asked Questions
- What is DOL HDR in Sony IMX415 camera modules?
DOL HDR, or Digital Overlap High Dynamic Range, is a feature in Sony IMX415 camera modules that captures multiple exposures (typically short and long) almost simultaneously using different sensor rows. This minimizes motion artifacts while preserving details in both bright and dark areas of a scene.
- How does e-con Systems’ e-CAM80_CUNX leverage NVIDIA Argus ISP for HDR imaging?
e-con Systems’ e-CAM80_CUNX streams alternating short and long exposures from its IMX415 sensor over CSI, which are then processed by the NVIDIA Argus ISP. The ISP fuses these exposures, adjusts gain and exposure, and applies noise reduction to produce high-quality HDR images in both indoor and outdoor environments.
- What are the advantages of using DOL HDR with NVIDIA Jetson platforms?
- Reduced ghosting in moving subjects due to near-simultaneous exposures
- Better detail retention in highlights and shadows
- Improved low-light performance with optimized ISP tuning
- Seamless integration for real-time processing in embedded vision systems
- How does DOL HDR image quality compare to SDR on e-con Systems’ e-CAM80_CUNX?
In SDR mode, very bright areas can lose detail, and shadows can appear overly dark. DOL HDR mode balances exposure by retaining highlight information and improving shadow visibility. On e-con Systems’ e-CAM80_CUNX, it results in clearer and more natural images under mixed or high-contrast lighting.
- What specific use cases benefit most from an IMX415 DOL HDR camera?
- Smart traffic and license plate recognition in varied lighting
- Robotics navigation in indoor-outdoor transition zones
- Industrial inspection with bright reflections and dark shadows
- Surveillance in environments with headlights or streetlamps
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.