Checkerboard HDR Infrared Imaging: Go 0 to HDR in 1 Frame!
Thomas Poonnen, PhD (Director of Engineering)
High dynamic range (HDR) infrared imaging is typically accomplished by combining two or more frames with different integration times. A frame with a long integration time I(L) can capture dark (cold) objects in the scene more effectively, while a frame with a short integration time I(S) can capture bright (hot) objects in the scene more effectively. When a long-integration frame is combined with a short-integration frame to form a dual-integration HDR frame, the dynamic range is improved by a factor of approximately I(L)/I(S). But, this improvement in dynamic range comes at the cost of reduced temporal resolution. When two frames with different integration times are combined, the frame rate, and therefore the temporal resolution, is halved. If objects in the scene move between frames, inter-frame motion blur is introduced.
When we set out to design the world's first 8 µm pitch dual-band DROIC - the Oxygen™ RD0092 - we couldn't resist to also try to make it the world's best. Among the many options and features we added to this 1280 x 720 format, 500 fps digital readout, perhaps the one that stands out the most is its ability to achieve >120 dB dynamic range in dual-integration HDR mode. And the reason it stands out is that the RD0092 does not require two frames to create an HDR frame, it instead accomplishes HDR imaging in a single frame.
The pixel array in the RD0092 can be configured to have alternating short-integration and long-integration pixels in a checkerboard pattern. Each short-integration pixel can be combined with four spatially adjacent long-integration pixels to obtain an HDR pixel. Similarly, each long-integration pixel can be combined with four spatially adjacent short-integration pixels to obtain an HDR pixel. This type of intra-frame HDR imaging achieves the same level of dynamic range improvement as conventional inter-frame HDR imaging, but without compromising temporal resolution as the dark (cold) and bright (hot) objects are captured in the same frame. The frame-rate is not halved and no motion blur is introduced. Additionally, the spatial resolution of the HDR frame is mostly intact, thanks to the checkerboard pattern that enables proximal HDR interpolation using neighboring pixels. In short, this think-out-of-the-pixel approach we took achieves the best of both worlds when it comes to dual-integration HDR imaging - a phenomenal improvement in dynamic range without any notable compromises.
The Oxygen™ RD0092 is presently the only commercially available readout that features this superior checkerboard HDR infrared imaging mode. Order yours today to go 0 to HDR in 1 frame!
About Senseeker Engineering
Senseeker is a wholly US owned transducer IC semiconductor company that specializes in the design of stateof-the-art digital imaging sensors and readout integrated circuits for hybrid infrared image sensing arrays. Senseeker's products and IP enable designers to produce world class infrared image sensing solutions. Read more at https://www.senseeker.com.
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