Omnivision recently announced the OV50K40, its first smartphone image sensor using the company’s TheiaCel single-exposure high dynamic range (HDR) technology. Claiming a new high-performance bar in the industry for flagship rear-facing main cameras, the OV50K40 is reaching human eye-level HDR with single exposure, the company said, getting close to what the human eye can see.
TheiaCel combines the capabilities of lateral overflow integration capacitor (LOFIC) and Omnivision’s proprietary single-exposure HDR technology to deliver an improved single-exposure HDR architecture for high-quality imaging. This is thanks to a wider dynamic range regardless of lighting conditions.
OV50K40 50-MP image sensor (Source: Omnivision)
Initially launching the TheiaCel technology last year in the automotive market, Omnivision is extending the technology to image sensors for mobile devices and other markets in the future. The first use case was to mitigate LED flicker in 2.1-µm pixel automotive applications.
With the OV50K40, TheiaCel is now being implemented in rear-facing main cameras in flagship smartphones to solve several challenges faced by mobile-phone designers. These include motion artifacts in traditional multi-exposure HDR schemes like staggered HDR and multi-frame HDR, making single-exposure HDR more desirable in smartphones, the company said.
Other challenges cited include LED light flickering in low-light conditions when the phone uses long exposure times and keeping dark area signal-to-noise ratio as high as possible, while expanding the dynamic range.
LOFIC is a key part of TheiaCel technology, said Arun Jayaseelan, senior product marketing manager, Omnivision. It mitigates LED flicker when taking videos and it also helps with high-brightness images that are hard to process on mobile phones, like sunsets, sunrises, in front of a bright window or at nighttime with bright lights, such as at a fair or downtown, or even fireworks, he added.
The OV50K40 with TheiaCel uses a four-cell on-chip QPD re-mosaic technology to provide the highest possible single-exposure image quality for smartphones. (Source: Omnivision)
“LOFIC has an overflow capacitor that is added under the pixel so we are able to capture a lot more photons than usual and in extremely bright areas or bright parts of your scene, we can capture more details,” Jayaseelan explained.
The OV50K40 delivers the highest possible HDR with single exposure, so there are no motion artifacts, he said. “There are some HDRs, which can get you a lot of detail but that is with multiple exposures over time and if there is a moving object you would see a lot of artifacts. With the single exposure we’re able to get both the dark area details as well as the bright area details.”
The OV50K40 50-megapixel (MP) image sensor features a 1.2-micron (µm) pixel in a 1/1.3-inch optical format with high gain and correlated multiple sampling (CMS) for optimal performance in low-light conditions. Built on the company’s PureCel Plus-S stacked-die technology, enabling high resolution with 1.2-µm pixels, the OV50K40 supports 4-cell binning for 12.5 MP at 120 frames per second (fps) and 60 fps with HDR, with 4× sensitivity for flagship-level low-light performance.
The OV50K40 also features quad phase detection (QPD) that enables 2×2 phase detection autofocus (PDAF) across the sensor’s entire image array for 100% coverage, resulting in ultra-fast autofocus performance. The on-chip QPD re-mosaic enables full 50-MP Bayer output, premium-quality 8K video and 2× crop-zoom functionality.
“With QPD we have 100% coverage, so it increases the autofocus speed, and the QPD re-mosaic helps output the full 50 MP,” Jayaseelan said. “Those two factors, re-mosaic and the fast autofocus, make it a good option for crop zoom.”
The OV50K40 is in mass production. Samples are available for evaluation.
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