I wasn't able to join in the live AMA with @WesleyLee
but I want to echo what others said and say that we really appreciate any
member of the HMD team (or your partners!) taking some time to answer our questions. We will never be wholly satisfied, we will always have more questions, always want more of your time and never be 100% satisfied or in agreement with your answers! But
that it why I think that dialogue with the community is so important and rewarding for both HMD and us - the more we ask and answer the more we learn about each other and what motivates the other.
There were a few answers from Wesley that prompted more questions from me but I didn't have chance to write them before the thread closed, so here's my attempt at continuing the conversation:
Hi @Kirti Arora
thanks for the question.
At the time of launch, Nokia 808 PureView was a great
innovation – bringing zoom to a smartphone camera. At that time, there were no
optical tele lens, no AI super resolution algorithm. Nokia 808 PureView was the
first product to bring lossless zoom experience by cutting the pixel count
approach. But there was a trade off in using the pixel counts to bring the
lossless zoom experience or using the pixels count for pixel binning as a
result of the more sensitive virtual pixel which is better for low light
Imaging technology has advanced since then, AI has had
an impact on imaging quality. Today, AI algorithms can enhance zoom quality a
lot more compared to a few years ago. Also, tele lens solutions are a possibility
in camera modules already – although it is relatively expensive right now.
In short, there are other options available to
preserve pixels for pixel binning to enhance both low light and day time image
quality and use either algorithms or tele lens approach or a mix of both to
deliver great quality zoom pictures.
There are a few things I want to pick up on here:
1. Comparison with the 808 PureView is an interesting but obsolete benchmark, because the successor (the Lumia 1020 PureView) brought OIS and a backside-illuminated sensor whilst the later models brought further improvements in image processing and post-processing capabilities. The real benchmark which Wesley should have considered is the 950/950XL camera.
2. Referring to pixel-binning for the PureView cameras isn't quite correct AFAIK, because they actually used an oversampling method which is must more sophisticated than quad-pixel-binning, as it actually uses more than 4 adjacent pixels to create one pixel, e.g. going from 38MP to 8MP is not a factor of 4... nor is going from 20MP to 8MP... Similar for video resolutions.
3. I don't know what is meant by "sensitive virtual pixel".... but the 950/950XL is excellent at lowlight photography, sometimes too good to be believable.
4. AI algorithms can enhance zoom quality... it would be nice to see some of these algorithms used on HMD's phones! I'm serious, this is not a joke. I haven't seen any digital zoom examples from HMD's phones which are anywhere near as good as the old Nokia PureView phones. My Nokia 8 may be two years old but it the ISP is still better than the one in the 7.2 and 6.2 (in fact only the 8.1 and 9PV have better ISPs) and its digital zoom is terrible - it's better to take the full photo and crop later; I cannot believe there is any "AI" used in it at all. I haven't been able to test other HMD phones but I believe they will be very similar - can anyone confirm?
PureView was so far in advance of the competition at the time it was on the market and in many ways it is still more sophisticated. I have yet to hear a good technical explanation as to why it is no longer suitable. Note that Oliver from ZEISS explained to me that it was difficult to fit such a large sensor and its lenses in a phone now because the trend is for thin-ness, but Xiaomi are showing that this is not the case any more with their 1/1.3" sensor (wow!).
Edit: I'll explain my experience with the Nokia 8 a bit more. It is only a 13MP camera to compared to PureView models it has many less pixels, however, I don't see any technical reason why PureView algorithms could not (or indeed should not) be used.
At 13MP resolution I accept that oversampling and loss-less zoom are no possible because the camera can't provide more pixels, however, at lower resolutions they could be used to provide a much better quality:size ratio e.g. taking the 950XLs 20:8 oversampling ratio the Nokia 8 should be able to produce 5MP photos using oversampling and get much better image quality than a "standard" 5MP photo, but this is clearly not done.
Worse, when using a lower resolution and zooming the lack of oversampling approach means that the zoomed image is terrible. For example, instead of oversampling at 1x zoom and cropping in to the image for the zoom effect but maintaining the resolution, the camera crops into a lower resolution image, e.g. goes from 4MP to 1MP then upscales it to 4MP again... but without any apparent intelligence. The result is awful.