In good lighting the Galaxy S9+ and the Huawei P20 Pro capture photos that leave us struggling to pick one over the other. Where there are differences, they are minor and in areas that are open to subjective interpretation.
First things first, though - we're very much convinced that Huawei's Master AI needs some serious rethinking and as it stands right now, it's best left off. It's these Master AI-less photos that we'll be comparing in our analysis. Having said that, we're including a sample from multiple scenes with the feature on, so you know why we fell the way we do. You don't need to look for them to notice the vignetting of blue skies, heavily increased contrast, and pumped up the saturation in greens.
Turn off Master AI, and the Huawei P20 Pro will still have an extra few units of saturation in the greens and blues over the Galaxy, but in an entirely non-objectionable way. Or, if you're on the opposite side of the argument - more pleasant greens and blues than the Galaxy.
Noise reduction is one area where we're not seeing the typical difference we're used to observing between a recent Galaxy and pretty much every other phone. That's another way of saying that the P20 Pro's images are very much noise-free. And Huawei's done it without the slightly plasticky Samsung look. Nice.
The Huawei P20 Pro, like all Huawei flagships from recent years, also has a dedicated monochrome camera. You can have 20MP of black and white melancholy, something you can't get from the Galaxy S9+.
We figured that with all the hype around the P20 Pro's zoom camera, a zoom comparison was in order. Now, since the Samsung's telephoto camera offers a 2x zoom, while the P20 Pro's is at 3x, we shot both phones at both magnification, meaning a digitally zoomed 3x from the Galaxy's telephoto cam and who knows what mathematics from the Huawei.
The Galaxy S9+' wide-angle camera is a 26mm equivalent, while the one on the P20 Pro is at 27mm. The Galaxy's tele is at 52mm, so we tried to match that with the Huawei. The P20 Pro says 80mm on the tin for the tele, while EXIF reports an 83mm equivalent - we just aimed for 3.0x on the Galaxy, which should be around a 78mm equivalent. There's a bonus shot from each scene with the P20 Pro set at 5x.
Overall, the Galaxy's telephoto camera isn't as contrasty as its main one and the Huawei P20 Pro has an edge in this respect. The truly optical nature of the S9+'s 2x shots do make them sharper and more detailed, if only just.
At 3x the Huawei's photos are sharper, with better defined detail, particularly with distant subjects. We're pointing that out because the snail shot, taken at a couple of meters of distance, is rendered much better on the Galaxy. You're likely going to be bringing distant subjects closer when using the zoom, so the P20 Pro should be the better option though not by a wide margin.