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.

Comparing 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 SuperSensor, a technique based on multi-frame super resolution, running on the same Pixel 3 smartphone:

It looks like Almalence SuperSensor is closer to be delivering on the “optical zoom” promise.

Another nice example 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 artefacts are introduced on the originally black text:

And again, if you really want to capture a readable text, Almalence SuperSensor is a solution (note that SuperSensor also got the white color of paper right):

Unfortunately, there is no way to reliably measure the 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 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.

PS Stay tuned, we will soon show a comparison of super resolution zoom at video frame rates!

Google Super Resolution Zoom: Good Start but Long Way to Go

Please read the updated post.

After publishing this original post we were contacted by Google engineers who pointed to the fact that Super Res was not always on in the images we took. Of course, it happened unintentionally, there’s just no obvious way to make sure that Super Res kicks in when taking an image.

We have re-taken the test images as suggested by Google and we admit the results are much better now. However Almalence SuperSensor is still superior :).