There is a very interesting article on Business Insider India which foolishly states that 48-megapixelsjust means a larger photo but not better image quality. This article popped up around December when the chatter on the Internet indicated that the Xiaomi Redmi Note 7 pro would have a 48-megapixel camera. This was the trumpet that was paraded by experts in the early 2010s for smartphone camera systems and in the 2000s for digital cameras. And they were mostly right back in the day. But somewhere around 2015, most leading smartphone brands settled in on around 12-megapixels as the optimal resolution for a flagship-grade smartphone camera. But today when Xiaomi actually globally unveiled the Redmi Note 7 Pro, it actually went ahead and launched the phone with a 48-megapixel camera with the company claiming better image quality than even the iPhone XS Max and OnePlus 6T — phones that cost anywhere more than 3x to 7x. So what has happened here? Is Xiaomi pandering to its marketing teams or there is some technological progress that a phone which costs 7x less than an iPhone can actually have a better camera than it? That would be a huge coup for people camera junkies on a budget, right? Let me explain.
Sony’s IMX586 sensor is a different kind of sensor
At the heart of the experience here is the Sony IMX586 sensor which was announced in January 2018. This sensor has been designed keeping in mind low-light performance and that’s why the high 48-megapixel resolution is coupled with a large sensor size, a stacked CMOS layout and a quad Bayer pixel setup optimised for pixel binning and computational photography something that’s been seen on phones like the Huawei Mate 20 Pro and formerly the Nokia PureView 808 — both these phones also boast ultra-high resolution cameras. In fact, Xiaomi isn’t the only manufacturer using this sensor; both Vivo and Honor are using this very sensor in the V15 Pro and Honor View 20 — which are phones that cost a great deal more than the base model of the Redmi Note 7 Pro. Suffice to say, it is unique, not just a small sensor with a 48-megapixel resolution.
How is it different from traditional smartphone cameras
A traditional smartphone sensor would just shoot the photo at the given resolution which would not be a great thing as that Business Insider article pointed out. Why? Even with a huge 1/2-inch sensor with a 48-megapixel resolution images convert to very poor sub-pixel size which would lead to poor low light performance and dynamic range. And Sony also outlines that this sensor has 0.8-micron subpixels which is significantly lesser than 1.25-microns on the iPhone XS or 1.4-microns on the Google Pixel 3. As mentioned above, using pixel binning techniques, the Redmi Note 7 Pro camera is able to fuse neighbouring pixels which are of the same colour to create 1.6-micron superpixels which are deployed at a 12-megapixel resolution hence elevating dynamic range, low light performance and even preserving good levels of detail compared to most smartphone cameras.
For prosumers, 48-megapixels can be handy
Xiaomi has hidden the 48-megapixel mode in the“pro”mode as most people wouldn’t be able to extract the advantages from the 48-megapixel camera. With 48-megapixels on tap, Xiaomi is using an unusually large smartphone sensor but people who know their way around camera settings will be able to eke out a lot from the high-resolution camera especially if they crop into details like text. This was witnessed by me in some image samples Xiaomi shared and that’s why this phone is said to pull ahead of even the iPhone XS. This headroom isn’t available on other camera phones apart from the Honor View 20 and Vivo V15 Pro which are admittedly more expensive.
Qualcomm Snapdragon 675 has a flagship grade ISP
One of the ways that there is so much performance that’s being eeked out of the Redmi Note 7 Pro camera is because it uses the Qualcomm Snapdragon 675 processor. This is a new chipset which currently is only on the Vivo V15 Pro and that also happens to be one of the phones that shares the same Sony IMX586 48-megapixel sensor. There are two reasons for this — a) This chipset is one of the few that supports triple cameras and a resolution of 48-megapixels, b) it uses the same ISP as the top of the line Qualcomm Snapdragon 855 which was launched back in December and will be seen on all high-end smartphones this year. This helps the phone deploy some incredible computational photography capabilities which include AI based improvements to image quality and the portrait mode depending on the software stack of the manufacturer.
Xiaomi’s AI algorithms for imaging are well optimised
Xiaomi has deeply invested in AI for its camera stack. It has a dedicated team working on camera algorithms which have improved its cameras by leaps and bounds in the last two years. Its high-end phones like the Mi Mix 3 and Mi 9 have been topping the charts on the DxOMark, but more than that even in real-world performance more affordable phones like the Poco F1, Redmi Note 6 Pro and Mi A2 have showcased some impressive image quality. If one considers these improvements and some more iterative ones as claimed by Xiaomi today, when coupled with this new generation camera sensor, with new generation SoC one should be looking at a big leap in image quality. It should also be considered that Xiaomi’s camera algorithms are better than Vivo’s which will make a difference in the image quality of pictures taken from both the phones. Xiaomi has nailed this aspect and particularly its AI-based portrait mode and night mode are great examples of computational photography taking a centre stage. And remember, the night mode isn’t even on the iPhone XS.
All this means that we could be looking at a generation of computational cameras that were first only accessible to high-end iPhone and Google Pixel customers, now being commoditised to a point where similar or better capabilities are coming to the mid-range which is most crowded space in the smartphone market. So yes, I do believe, that the Xiaomi Redmi Note 7 Pro is a big deal for camera junkies on a budget. But I will have more on this when I start testing the phone.