With its new 200-megapixel Isocell HP2 image sensor, Samsung aims to offer smartphone photographers the best of both worlds: high resolution and good image quality in challenging conditions.
The HP2 is in mass production. Samsung has not announced the ship date nor confirmed which phone it will arrive in. Still, the sensor is expected to power the main camera of the company’s flagship Galaxy S23 Ultra phone, which is likely to debut on February 1.
Image sensor designers face a trade-off. By increasing the resolution, each pixel on the sensor is smaller, and smaller pixels are also unable to capture light. That means shots taken in low light are marred by specks of noise. They lose detail in shadowy parts of a scene. And they suffer from blown-out highlights in bright areas like the sky.
However, the HP2 brings new methods to counter those issues and get the most out of every photon of light, Samsung revealed exclusively to CNET.
Primarily, the South Korean electronics giant’s sensor can capture light more effectively and boost HDR (High Dynamic Range) photos to better handle scenes with dark and bright elements, the company said. And when shooting at the full 200-megapixel resolution, Samsung uses AI technology to bring out the finest details.
It is not yet clear how well the sensor will perform in field tests. But it’s no surprise that Samsung is targeting the technology. Camera improvements are a major reason to upgrade phones, with better photos and videos more noticeable than marginally better processors, battery life and network tech.
“The full 200MP resolution is especially useful when shooting at concerts or outdoors where a lot of detail needs to be captured,” said JoonSeo Yim, executive vice president of the sensor division of Samsung Electronics. “It may not be the predominant setting for most consumers, but we certainly see the need for highly detailed images.”
Apple, Samsung’s biggest smartphone rival, is also investing heavily in its cameras. Relatively large lens elements protrude from the back of iPhone 14 Pro models to show off camera performance, and Apple has upgraded its sensors for better high-resolution and low-light shots.
Better pixel binning options
One of the most important techniques for enhancing smartphone photos is called pixel binning. It allows groups of physical pixels to be combined into larger virtual pixels that capture more light when it’s dark, trading resolution for less noise and better colors.
Samsung is not alone in using pixel binning. You see it in the Apple iPhone 14 Pro, Google Pixel 7, Xiaomi 12T Pro and other phones, but the HP2 sensor is one of the most advanced. For example, Apple and Google use 2×2 pixel binning that turns four physical pixels into one virtual pixel. Samsung’s flagship Galaxy S22 phones have offered 3×3 pixel binning since 2019, with 108-megapixel photos in good light and 12-megapixel photos in low light.
Samsung’s HP2 can take 200 megapixel photos in good conditions. If it’s fainter, pixel binning groups pixels into 2×2 chunks for a 50-megapixel image. And when it’s even dimmer, Samsung’s 4×4 “Tetra2pixel” chunks take a 12.5-megapixel photo.
The two levels of pixel binning were available on the 200-megapixel HP3, announced in 2022. However, the HP3 uses smaller pixels which, while minimizing camera mass, aren’t as good at capturing light in the first place. The HP1 announced in 2021 also had it. But the HP2 adds some other tricks that the HP1 lacks.
Pixel binning ups and downs
Pixel binning has some other advantages. Cameras can zoom in on the central part of the frame to zoom in on subjects further away. It’s an important foundation for the effort to give smartphones zoom capabilities like traditional camera lenses. Pixel binning also opens up new options for high-resolution 4K and 8K video.
However, pixel binning has drawbacks. Processing all those pixels takes a lot of battery power, and storing high-resolution photos eats up a lot of storage space. And high-resolution sensors, while beautiful in principle, don’t achieve top image quality unless paired with high-end lenses.
“The full 200MP mode requires more RAM and power,” said Yim, which is why such high-resolution sensors are only found on high-end smartphones.
One complication with the HP2 is figuring out color when shooting 200 megapixel photos. Digital cameras capture red, green or blue light for each pixel, but the Tetra2pixel design means that each 4×4 pixel group captures only one of those colors. To help fill in the necessary color details within those 16-pixel groups, Samsung uses an artificial intelligence algorithm, the company said.
Photography enthusiasts — a population likely very interested in the sensor’s high resolution — can capture raw images at 200 megapixels, Samsung said. Raw images are larger, but offer higher image quality and editing flexibility than conventional JPEG or HEIC photos.
Samsung HP2 image quality improvements
The sensor has other tricks to improve image quality, especially in high dynamic range scenes with both bright and dark details. Here are a few:
- A technology called Dual Voltage Transfer Gate (D-VTG) gives each pixel a 33% better ability to capture light, which should improve image quality in dark scenes and reduce washed-out white spots in bright skies.
- Samsung’s Dual Slope Gain (DSG) feature enhances HDR photos by digitizing each pixel’s exposure data at two different scales to collect bright and dark data when shooting in 50-megapixel mode. Due to the abundance of pixels on the sensor, some pixel quartets are tuned for bright light and others for lower light.
- A related feature called Smart-ISO Pro is a separate HDR technology that adapts to different scenes, using different combinations of sensitivity settings to suit the different frames used to create the HDR photo.
Another new feature in the HP2 is improved autofocus with a technology called Super QPD. It can recognize both horizontal and vertical lines across groups of 2×2 pixels, allowing the camera to capture details like horizons or tree trunks even when it’s dark, Samsung said.
Each HP2 pixel is 0.6 microns or 6 millionths of a meter wide. That’s a shade narrower than the HP1’s 0.64 microns, meaning the HP2 is a slightly smaller image sensor at 11.3 x 8.4mm. For comparison, a human hair is about 75 microns wide. Combined into a 2×2 array for 50 megapixel photos, the pixel width increases to 1.2 microns and in 4×4 to 2.4 microns.
“We expect high-resolution image sensors to become a standard feature in future flagship smartphones,” said Yim. “That’s why we feel it’s important to continue our efforts, from advanced pixel processes below 0.5 microns to pixel performance and algorithms.”
Larger sizes are better at collecting light. Samsung’s pixel sizes are similar to the iPhone 14 Pro’s main camera sensor, which uses 2.44 micron pixels in 12-megapixel mode and 1.22 micron in 48-megapixel mode.
When it comes to video, the HP2 has a lot of options. It can shoot 8K video at 30 frames per second by using the sensor in 50-megapixel mode. It can shoot 4K video at 120fps, or, with Smart-ISO enabled, at 60fps. For 1080p video, the sensor shoots at 480 fps without autofocus and 240 fps with autofocus.
Correction, 2:48 PM: This story misrepresented the pixel size on the Samsung Isocell HP1 image sensor. Each pixel is 0.64 microns wide.