ISOCELL Unlock the Future of Camera Experiences [Tech Day 2022]

Undoubtedly, Samsung is a leader when it comes to leading innovations in technology. Also, in development of high-performance image sensors brought the enhanced quality of photos and videos. While in order to share its recent improvements and future endeavors. Specifically for various system LSI-related technologies that include image sensors, conducted its Tech Day 2022 event. On this occasion, Joonseok Kim, the Vice President, and the Head of the Project Management team bring up the key areas of smartphone photography and videography. While the motive of this discussion is to reveal how Samsung progressively develops image sensors. In order to improve the quality of content captured with them.

Since Image sensor technology has grown a lot the photo captured by a smartphone is tantamount to those captured by professional digital cameras. Here, sensor technology is of the essence. But corresponding software for multi-frame noise reduction, HDR and AI, related to certain other aspects have also been critical to this drastic evolution.

The application of cameras has also emerged a lot in the last few decades. Apart from images, it is most intensively used for videos now. This is to be more compelling with the commencement of popular social media apps. Therefore, there is a gap between still images and video, and filling that gap seems to be difficult.

The reason behind Smartphone Video Hasn’t Yet Caught Up

The primary reason behind the smartphone video quality lags is the inclusion of visual “noise” specifically in low light. This is due to the lack of exposure time that is needed to capture sufficient light at 30 frames per second (fps) in video mode.

While the second cause is high-dynamic range (HDR) images. Since it’s difficult to show the actual colors of an object and also the background in complex light situations. In order to make this work, a smartphone needs to run multi-exposure and multi-frame fusion through system-on-chip (SoC). This uses more memory and power to be practical.

Lastly is the lack of depth-sensing capabilities. As one of the best and ever-used features of a DSLR camera is the “bokeh” which is the pleasant-looking blur. Therefore, while using SoC, a user can take photos in which the subject stands out from a blurred background. Whereas in the case of video, this method isn’t practical for the same reasons as that of HDR.

“We decided that we needed to solve these problems with sensors as opposed to software, and we’re taking a three-part approach. First, we’ll be making improvements in light and exposure sensitivity, which has been a big challenge, especially for small and thin smartphone cameras,” said Kim. “Second, to increase the luminance of range we are working on 12-bit and 14-bit sensors, and towards even higher dynamic range sensors for superb HDR. And thirdly, we are developing ToF (Time-of-Flight) sensors that detect true image depth. Our goal is to provide a precise bokeh for smartphone video and other 3D applications.”

Advanced ISOCELL Pixel Technologies

The technology that enhances pixel quality has undergone consequential progress in a couple of years. In order to capture as much light as possible. The pixel structure has been acquired from front-side illumination (FSI) to back-side illumination (BSI).

On the other hand, the minus of this structure is that it generates higher crosstalk between pixels that leads to color impurity.

“To remedy such a drawback, Samsung introduced ISOCELL, its first technology that isolates pixels from each other by adding barriers. The name ISOCELL is a compound word from the words “isolate’ and ‘cell,’” Kim explained. “By isolating each pixel, ISOCELL can increase a pixel’s full well capacity to hold more light and reduce crosstalk from one pixel to another.”

Additionally, by the time of its origination, the ISOCELL pixel technology has seamlessly emerged. And also its new generation enhancements are continuously being applied to the latest image sensors. Considering the case of ISOCELL adopting optical walls now. It is made up of innovative low-refractive material between the color filters.

 In addition to that, Kim shared “We are developing another innovative high refractive nano-structure to utilize the light of adjacent pixels to extreme levels. By applying these nano-photonics technology, we’re achieving high sensitivity that goes beyond the usual limits.”

HDR Technologies for True Colors

The conventional image sensors only support 10-bit images at about 60dB dynamic range. But in order to capture very small details in multiple scenarios, sensors need to support at least 14 bits. Therefore, for still images, one of the optimum solutions is multi-exposure image capturing. Also, this technique takes a long exposure image for the dark sections and then a short exposure image for the bright section respectively. And the two images are merged in order to generate an HDR image.

On the other hand, this method comprises several problems for videos. Out of many, the first is power consumption, as in capturing a 30 fps HDR video, it needs to shoot at 60 fps to acquire dual exposure. And to process such massive image data in real-time, it would need enormous power.

The next big challenge is to capture moving objects (motion artifacts). Multiple exposures mean merging the various images that capture at different moments. While the high-speed movement makes this merging of images very difficult and results in broken or irregular images.

To help resolve this, Kim shared that, “instead we are building an in-sensor, single exposure HDR-technology. This enables the process required on SoC to be simpler, consume less power and reduce the motion artifact effect for HDR video.”

Moving further, a dynamic range is a ratio between the signal with respect to the noise level. With the addition of ISOCELL technology, the image sensor has a very high capacity. This allows the sensors to hold out the maximum signal range.

Kim explained that, “To reduce noise, we perform two readouts: One with high gain to show the dark details and another with low gain to show the bright details. The two readouts are then merged in the sensor. Each read out has 10-bits. With the high conversion gain readout at 4x, it adds an additional 2-bits, producing 12-bit HDR image output. This technology is called Smart-ISO Pro also known as iDCG (intra-scene Dual Conversion Gain).”

Notably, with recently launched ISOCELL HP3 offers 14-bit HDR with enhanced iDCG. Subsequently, the company has the plan to bring 16 bits of HDR sensor in the near future.

ToF Technology for True Depth

ToF is a technology that calculates the distance by measuring the time when a light source sent towards an object is reflected and returned. It comprises the transmitter that discharges light and a receiver that receives the reflected light. While ToF has been installed in Samsung’s flagship devices such as the Galaxy S and Note in the past.

Furthermore, this is the first time that Samsung Electronics’ medical device business division will be going to launch an X-ray with ToF. Thereby using this module, the thickness can be measured, and depth information as well. Parallelly, it enables three-dimensional information such as shape, volume, and density from the thickness of bones and soft tissues. Therefore, it increases imaging precision as compared to conventional X-rays. While it also lowers the number of X-rays which reduces the patient’s exposure to radiation.

The above innovations depict that Samsung rigorously works to smoothly deliver clearer and better quality images that can easily be captured through mobile devices.

“With our future technology, we aim to keep changing and improving the ways our users capture images and video, and close the quality gap between the two. Our goal is to create solutions for the future through sensors that enhance human life, making it better, safer, and healthier,” Kim shared to close the presentation.

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