Every smartphone manufacturer believes the camera on the company’s high-end product is the best in the market. Image quality is, however, very difficult to prove. Countless camera tests among the top smartphone brands have been published, but because people tend to favor different attributes in images, tests conducted by asking viewers’ opinions don’t produce an unambiguous winner. When image quality is technically measured in a lab, we get some interesting results.

At the moment (in the second half of 2015) the best smartphone for photography is the Sony Xperia Z5. The Samsung S6 Edge is the second best and the Google Nexus 6P the third. The tests have been conducted by DXO in a laboratory using measuring instruments.

Here is the top 20 list for the best smartphone cameras:
1. Sony Xperia Z5
2. Samsung S6 Edge
3. Google Nexus 6P
4. LG G4
5. Samsung Note 4
6. Moto X Style
7. Sony Xperia Z3+
8. Apple iPhone 6Plus
9. Apple iPhone 6
10. Apple iPhone 6s

11. Samsung S5
12. Sony Xperia Z3
13. Sony Xperia Z2
14. Google Nexus 6
15. Nokia 808 Pureview
16. Sony Xperia Z1
17. Apple iPhone 5S
18. Samsung S4
19. Lumia 1020
20. Nokia Lumia 925

Sony and Samsung have a large selection of smartphones, and these two brands performed well in the tests. Sony acquired Konica Minolta camera business in 2006, so it is not a surprise that its camera know-how shows in smartphones as well. Apple and Nokia have performed well in camera tests where human eye has determined the result, but DXO test system gives different results.

Years ago, when tv monitors still were CRT tubes, a tv manufacturer advertised that it has the most natural colors. Lab tests showed that it was not the case, but it didn’t matter: people bought the product anyhow. The tv monitors were adjusted to please the human eye. Who knows if Apple and Nokia have adjusted their imaging algorithms to please the human eye?

In a digital camera, multiple components, like the lens, image sensor (that captures the light), software algorithm (that transforms the light into image data), stabilization mechanism and speed of hardware affect the image quality. The company behind the lab tests, DXO, has developed a system known as DxoMark for testing and ranking camera test results. DxOMark measures camera sensors for:
– ISO sensitivity (speed)
– Noise (standard deviation, signal-to-noise ratio, dynamic range, and tonal range)
– Color sensitivity
DxOMark measures lenses (mounted on cameras) for:
– Resolution, derived from the MTF (Modulation Transfer Function) measurement
– Distortion
– Vignetting
– Light transmission (T-stop)
– Chromatic aberrations

A video from DXO lab shows how a smartphone test is carried out: