Block diagram of the 20 MP Toshiba T4KA7 camera sensor in the HTC One M9
HTC One M9 camera tip suggests a 20 MP Toshiba sensor with proprietary pixel design
By now it's clear for everyone and their goldfish that the HTC will finally do away with the low-res UltraPixel shenanigans, moving them to the front of the upcoming One M9 flagship, and equipping the main camera with a hearty 20 MP sensor, just like in Sony, Meizu and some other phones. This is the highest resolution that the Android kingdom currently offers, and so far these resolute sensors have mostly been built into Sony phones, as Sony is the one supplying the vast majority of sensors for mobile cameras, including the 20 MP endeavors.
The HTC One M9, however, is allegedly straying away from the pack, and will utilize a 20 MP camera unit with a sensor made by Toshiba instead, indicating that we might see a different level of photo quality than we are accustomed to with Sony sensors. Those have, frankly, not been very impressive results, 20 MP or not, as can be attested by our camera comparisons with the Xperia Z3, though it might be due to Sony's software optimizations, too.
Looking for 20 MP mobile sensors that Toshiba currently offers, we can actually only see one, the recently announced T4KA7. Besides the usual high-end stuff, like backside illumination, real time HDR support, and 1080p video recording with up to 90fps, this Toshiba sensor is somewhat unique in the rest of its specs. For starters, it offers square pixels. While still at a tiny 1.2 micron size, like all high-res mobile sensors, Toshiba claims that the sensor "utilizes a proprietary square-pixel design that enables exceptionally high-quality images with low-power consumption."
The rest of the specs are a 1/2.4" size, 5384 horizontal and 3752 vertical signal pixels, and 22 fps recording at the sensor's full resolution. Sony's coming with a new sensor for the Xperia Z3, most likely the 20 MP IMX230, which has phase detection autofocus built in, so the battle of the smartphone cameras will be fierce this season, as all flagships will be equipped with high-res, state-of-the-art units, and powerful image processor. Thus, the photo and video quality might boil down to the software optimizations that each manufacturer manages to code in. This might explain the thoroughly overhauled Sense 7 camera interface, nuggets of which you can see in the purported spy shots below.