What is lossless zoom and how does it work in the Lumia 1020 and Xperia Z1?


Smartphone cameras have been improving at a rapid pace, and while the field owes credit to many, it is Nokia, and as of late -- Sony -- that are at the helm. Every year, we're treated to larger sensors, more and bigger pixels, larger apertures, OIS, and more features than we can count. But one thing has been missing for a long while now, and that's proper zoom. After all, many a situation necessitate that you either get closer, or miss the shot, and in those cases you're pretty much done for if you have to rely on the traditional digital zoom. Sure, the objects do appear closer, but the price is often a prohibitive loss of detail, as the images are upscaled to the desired resolution with no regard to the actual resolution -- the image is stretched by the software, which then attempts to fill in the blanks as best as it can. Well, thanks to the giant sensors on the Nokia Lumia 1020 and Sony Xperia Z1/Z1 Compact, zoom is no longer a problem. But instead of opting for bulky zoom lens (Galaxy S4 Zoom), they both rely on their massive resolution in order to get what we call 'lossless' zoom.

So what's lossless zoom, then? In simple terms, it means that zooming into a scene will only result in a negligible loss in quality. Think of it this way: there are so many pixels available with a camera like the one on the 1020 that you can 'crop' any part of the photo and still have more than enough pixels for a full-sized photo that will appear zoomed in. No upscaling, and no loss of quality. But how does it work in practice?


Starting with the Nokia 808 PureView, the fabled Finnish manufacturer has been increasing its lead in the camera department ever since. Equipped with a humongous 41-megapixel sensor, the 808 PV is still a beast to this date. As you can guess, much of the underlying tech behind the newer, Lumia 1020, was inherited from the 808. Lossless zoom is one of them. Some of you probably don't know this, but despite its massive sensor, the Lumia 1020 typically snaps 5-megapixel photos. Those are not comparable to your everyday 5-megapixel shooter, though, as they have been 'oversampled', meaning that you get 5 million 'super pixels'. These are created by combining information from neighboring pixels, and melding it into one, high-definition pixel. In result, stills are less blurry and noisy, and they're not as prone to artifacts. 

But back to zoom -- it's only lossless because there is such an abundance of pixels, as we said -- 34MP/38MP in 16:9/4:3 aspect ratios, respectively. So, instead of upscaling (loss of quality) when you want to zoom in beyond the resolution of your camera, the Lumia 1020 can zoom up to x3 in stills, without any considerable loss in clarity. As there are less and less extra pixels available as you crank up the zoom, the level of oversampling goes down as you zoom farther and farther, until it reaches zero at x6 zoom in 720p, for example. No further lossless zooming is possible at that point, as the level of zoom will go beyond the capabilities of the sensor, and it'll have to upscale (stretch) the shots, sacrificing detail. Best of all, since only the central part of the optics is being used during zooming, optical and geometric distortions, and vignetting, are all minimal.

We've talked quite a bit about Nokia, but that's only because the Sony Xperia Z1 and Z1 Compact and their 20.7-megapixel Exmor RS sensor go for much the same approach. And while the Z1 snaps 8-megapixel shots by default, the massive resolution still allows it crank up the zoom up to x1.8 times, without any significant loss in clarity. So not as impressive, nor as potent, but still a noteworthy feature.

reference: Nokia [1], [2], Sony

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27 Comments

1. aayupanday

Posts: 582; Member since: Jun 28, 2012

Pretty nice article for Smartphone Camera Newbies

3. Skoms

Posts: 118; Member since: Feb 03, 2014

My Z1 is really good. Made of steel

10. apple4never

Posts: 1064; Member since: May 08, 2013

its glass and aluminum dude....

15. vandroid

Posts: 405; Member since: Sep 04, 2012

I'm pretty sure they said that as an expression for it's durability

24. Ashoaib

Posts: 3298; Member since: Nov 15, 2013

Hahaha... comment of Skoms is really enjoyable... may be sony has done special favour on him by making Z1 out of steel...

14. akki20892

Posts: 3902; Member since: Feb 04, 2013

N8 the grandfather. 808 the father. 1020 the son. Epic family.

17. adecvat

Posts: 646; Member since: Nov 15, 2013

Son has dishonored his family.

19. papss unregistered

But is laughing at all other cameras on phones..

25. Maddy

Posts: 31; Member since: Sep 13, 2012

its not son's fault, what son can do ..his father slept with a btch M$

2. starandmountain

Posts: 53; Member since: Apr 01, 2012

nice story!

6. kaikuheadhunterz

Posts: 1157; Member since: Jul 18, 2013

You forgot to mention the Nokia Lumia 1520

29. rodneyej1

Posts: 3576; Member since: Jul 06, 2013

It takes great pictures, but horrible video.. Update seriously needed!!!!

7. yudi.nemesis unregistered

If I'm not mistaken Sony has used this technology in Cybershot since 2011

13. NokiaFTW

Posts: 2072; Member since: Oct 24, 2012

Yes, but Nokia was the first to bring it to a smartphone.

18. ArtSim98

Posts: 3535; Member since: Dec 21, 2012

My Sony Cyber-Shot DSC-WX150 has that clear image zoom. It's the only thing I don't like about it. The image quality actually drops kinda lot. But it has 10x optical zoom so it doesn't really matter lol.

9. pwnarena

Posts: 1129; Member since: Feb 15, 2013

pretty useless without steady hands or without using a tripod. when zoomed, the blurring effect of slight movements is amplified. it's better to just take a big photo that makes use of all the MP count of the camera and zoom later on.

12. papss unregistered

Agreed.. That's what I did when I had a 1020.

16. Bilpocalypse

Posts: 301; Member since: Oct 13, 2012

That's where OIS comes in on the L1020. It takes alot of that shake out of the equation. That being said, I agree that it is better to take the big photo... especially when you consider that the L1020 can save the photos uncompressed.

21. rency0722

Posts: 158; Member since: Jun 12, 2013

What? G sensor? You mean Exmor RS sensor, G Lens...

22. StraightEdgeNexus

Posts: 3689; Member since: Feb 14, 2014

Wasn't this article already posted a week or two ago.

23. Chris.P

Posts: 567; Member since: Jun 27, 2013

It was taken down temporarily. :)

28. ZiadMohamed

Posts: 21; Member since: Jan 09, 2013

Great and very useful article...keep it up we need more of this awesome useful tech. Stuff

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