Google Super Resolution Zoom: Good Start but not There Yet
Our first testing of Google’s super-resolution zoom recently announced in Pixel 3 shows that it indeed can restore some image details, but is still behind the best in class solutions.
Compared to the “normal” digital zoom, which is basically an upscaling plus edge enhancement, Google’s zoom reveals some details that are indistinguishable in the “normal” image:
However, it’s still not the best of what super-resolution can achieve. Below is a comparison of Google’s super-resolution zoom to Almalence Super-Resolution, a technique based on multi-frame super-resolution, running on the same Pixel 3 smartphone:
It looks like Almalence Super-Resolution is closer to be delivering on the “optical zoom” promise.
Another nice example was captured when taking zoomed images of a book on optical design. Google super-resolution makes the text somewhat better readable, however, some characters still remain distorted beyond any possibility to recognize them. Also, some minor color artifacts are introduced on the originally black text:
And again, if you really want to capture a readable text, Almalence Super-Resolution Zoom is a solution (note that Super-Resolution Zoom also got the white color of paper right):
Unfortunately, there is no way to reliably measure Google’s super-resolution processing time. It looks like the processing is performed in background. When trying to quickly open the image right after its icon appears in the camera app, the preview would still show a progress sign for a fraction of a second, probably implying that the image is still being processed. One can feel that the processing takes roughly one second altogether, but there is no way to verify that number. Almalence SuperSensor processing takes 200-500 ms on the same hardware (SnapDragon 845).
The full images used to make the above comparison examples are available in an archive below. Note: for an accurate comparison, the images of each scene were taken with the same Pixel 3 smartphone, from the same position under the same lighting. The zoom level might slightly differ between images as there is no way to precisely set the zoom factor in the Pixel 3 camera app. The Pixel 3 camera app, updated to the recent version as of Jan 25, 2018, was set to “HDR+” mode.
UPD: Almalence Super-Resolution improves smartphone camera zoom real time at video frame rates:
Full images used in this post: