Photography is a complicated field that requires a lot of knowledge about camera sensors, optics, and more in order to make sense of technical jargon. The quality of smartphone cameras has improved by leaps and bounds over the last few years, thanks to advances in image processing (such as image stacking as employed by Google’s HDR+ technology), camera sensors, lens optics, and technology such as Samsung’s ISOCELL.
The Android world competed in the smartphone camera megapixel (MP) race before concluding it a few years ago. Pixel size gradually decreased even as sensor sizes increased, thanks to the increase in camera resolution. The pixel size in smartphone cameras decreased from 1.75µm to 1.4µm to 1.1µm, but has since then increased back to an average of 1.4µm (for 12MP camera resolution) for flagship cameras, although some phones do have cameras with pixel size of 1.0µm.
New challenges are faced at such relatively small pixel sizes. A well-known photography principle is that pixel size is more important than camera resolution. The trade-off between camera spatial resolution and pixel size needs to be balanced, as more spatial resolution can lead to more detailed photos in daylight, while having a detrimental effect on image quality in low light because of the reduction in pixel size.
Reduction in pixel size meant reduction in light sensitivity and crosstalk, thus having a negative impact on image quality. Increasing pixel size is one of the traditional techniques to improve image quality in low light, but until a few years ago, pixel size was on a downward flow, as explained above.
Samsung notes that CMOS image sensors need to hold as much light (known as photons) as possible and transmit the right color information to the photodiode to take high-quality photos. The company developed ISOCELL technology to meet such requirements. ISOCELL forms a physical barrier between the neighboring pixels, thus reducing color crosstalk (interference). This enables each pixel to absorb and hold more light than conventional BSI image sensors for superior image quality.
Now, Samsung has introduced ISOCELL Plus technology which allows CMOS image sensors to capture more light, increasing light sensitivity and color fidelity. It does this through an optimized pixel architecture. In the existing pixel structure, metal grids are formed over the photodiodes to reduce interference between the pixels, but this can also lead to some optical loss as metals tend to reflect and/or absord the incoming light.
Therefore, Samsung replaced the metal barrier for ISOCELL Plus with an “innovative new material” developed by Fujifilm, thus minimizing optical loss and light reflection.
The new ISOCELL Plus delivers higher color fidelity along with up to a 15-percent enhancement in light sensitivity. It enables image sensors to equip 0.8µm and smaller-sized pixels without any loss in performance, according to Samsung. This is said to make it an optimal solution for developing super-resolution cameras with over 20MP resolution.
“We value our strategic relationship with Samsung and would like to congratulate on the completion of the ISOCELL Plus development,” Naoto Yanagihara (Corporate Vice President of Fujifilm) stated. “This development is a remarkable milestone for us as it marks the first commercialization of our new material. Through continuous cooperation with Samsung, we anticipate to bring more meaningful innovation to mobile cameras.”
“Through close collaboration with Fujifilm, an industry leader in imaging and information technology, we have pushed the boundaries of CMOS image sensor technology even further,” Ben K. Hur (Vice President of System LSI marketing at Samsung Electronics) stated. “The ISOCELL Plus will not only enable the development of ultra-high-resolution sensors with incredibly small pixel dimensions, but also bring performance advancements for sensors with larger pixel designs.”
ISOCELL Plus shows potential on paper as it can improve low light image quality in smartphones. The mentioning of the 0.8µm figure implies that Samsung is confident about being able to competently handle crosstalk at such a tiny pixel size. The timing of that announcement also shows some hints. Samsung uses ISOCELL sensors (along with Sony sensors) for its flagship devices (as well as many budget and mid-range devices). It’s possible that the Samsung Galaxy Note 9 (due to be unveiled on August 9th) and/or the Galaxy S10 Plus will feature this technology. At this point, this is impossible to verify, though.
Samsung’s ISOCELL Plus tech will be showcased at MWC Shanghai, which is being held from June 27-29.
Source: Samsung