The early high dynamic range technology typically adopts the technique that a HDR image by combining multiple images which shot in different exposure value, the working theory is the camera shoots two images with lower and higher exposure then combine them to generate the HDR image. This method has been widely used in digital still cameras, cameras for smartphone and more consumer products. However, this technology has not been successfully utilized in video shooting since it limits the frame rate. Thereafter, Sony increased the HDR support to its CMOS image sensors, mainly by leveraging two ways including Binning Multiplexed Exposure (BME-HDR) and Spatially Multiplexed Exposure (SME-HDR).
Adopting the Sony BME-HDR, through setting different exposure value on each two lines of pixel in CMOS image sensor, then combining pixels to achieve high dynamic range image, but it will compromise the image resolution, BME-HDR technology has been employed in Sony IMX135, IMX258 etc CMOS image sensors.
On the other hand, the SME-HDR is another technical algorithm based technology to achieve high dynamic range image by capturing a frame of image. Check the figure 2, an image contains different arrays of RGB pixels, each RGB colors have lower, standard, higher exposure value, then leveraging Sony’s unique algorithm to generate a HDR image without compromising resolution and frame rate. However, Sony doesn’t reveal the details what the algorithm is.
SME-HDR has been used in Sony’s mass production CMOS image sensors including IMX214, IMX298, IMX230, additionally the IMX377 and IMX378 also support this technology, e.g. it can enable IMX378 to support 4K (10bit) resolution 60fps video capturing in SME-HDR mode.