This article originally appeared on ABACUS Everyone wants a bezel-free phone, but nobody can agree on what to do with the selfie camera. Apple has the notch. Samsung has a hole in the screen for the camera. And Vivo hides the camera in a motorized pop-up module. Now Oppo and Xiaomi are taking a huge step forward with what promises to be the most natural solution of all. Oppo recently teased a new phone prototype in a video clip posted on Weibo and Twitter. The display appears to have no bezel around it or notch at the top. Yet when the camera app is launched, the screen displays what appears to be the ceiling viewed through an imperceptible front-facing camera. The person demonstrating the phone hovered a finger above the camera to prove the video’s authenticity. Hours later, Xiaomi executives released a video of their own phone prototype with an under-display camera. Xiaomi’s video, company co-founder Lin Bin made sure to mention on Weibo , was shot last month. The Xiaomi prototype appears to be a modified Mi 9, Xiaomi’s latest flagship. It could be the answer to all of the weird selfie cameras we've seen recently. We’ve seen the teardrop notch , the pop-up selfie camera and the hole-punch display . There's also a smartphone with a second screen on the back just so you can use the rear cameras for selfies. One Xiaomi flagship uses a sliding screen design. And this peculiar design by Asus allows the rear camera to flip up 180 degrees to face the user. None of these designs are easy to achieve. But it’s particularly hard to hide the camera under the screen while making it invisible when not in use. Samsung first discussed the idea last year, but the company said just last month that it won’t be ready for another one or two years. Xiaomi's Under-Display Camera Technology could be the ultimate solution for a Full Screen Display coexisting with a front camera! RT if you love it. #InnovationForEveryone pic.twitter.com/8e7EdEBn8J — Wang Xiang (@XiangW_) June 3, 2019 Oppo and Xiaomi’s technical solution for their under-display cameras are slightly different, and solutions by other mainstream smartphone vendors vary, too. But the core problem every company faces is solving the light transmittance issue, according to IDC analyst Xi Wang. Having a display over the camera module means the display must have a high enough light transmittance rate. But even after smartphone makers drop the PPI (pixels per inch) to let more light through, the light transmittance rate can only reach 70% at best, Wang said. The ideal rate is 90%. To compensate for this, companies need to develop algorithms for photo processing that cranks up brightness and adjusts the colors, according to Wang. Even Oppo’s own executive Shen Yiren said on Weibo that it’s hard for under-display cameras to match the performance of normal cameras at this stage. “There’s bound to be some loss in optical quality,” he said. Given the level of complexity, this technology isn’t yet ready for consumers, which is why companies are just teasing it for now. Wang estimates that under-display cameras won’t come to consumers earlier than the third quarter, and then it will only be seen on certain high-end flagships. Many people might even prefer to avoid first-generation tech. Shenzhen-based Royole put out the FlexPai in time to boast the world’s first foldable smartphone, but it was chock-full of bugs and not pleasant to use. Even once the more reputable Samsung got the Galaxy Fold out, things didn’t go well . Most people, though, are excited to see under-display cameras ready for consumers. But some in China are also worried the tech could have a dark side. Recent news in China about people discovering hidden cameras in hotels led some people to worry about what under-display cameras mean for privacy. “Speaking of under-display cameras, am I the only one worrying that it’ll make secret filming in hotels easier?” asked one Weibo user. “If it’s put under the TV screen, do you smash the TV?” “Who dares go to hotels anymore?” another user commented on an article . For more insights into China tech, sign up for our tech newsletters , subscribe to our Inside China Tech podcast , and download the comprehensive 2019 China Internet Report . Also roam China Tech City , an award-winning interactive digital map at our sister site Abacus .