[Xperia Z3 General] radicans:
Comparison: iPhone5 vs Z3

So I managed to get some time to hang out with a friend with an iPhone 5s, and out of curiosity wanted to compare some photos. We also wanted to try to figure out more in depth what really differs between them.

First of all, here are the straight up pictures:

Z3: http://i.imgur.com/68ETl6s.jpg

iPhone5: http://i.imgur.com/3eflDYr.jpg

It will come as no surprise to you that I prefer the iPhone 5s photo. Both because of subjective reasons, such as color balance, but also I think that the 5s produces a cleaner image with less processing. In the trees again you can find the dreadful cross-hatching in the Z3 pic.

Apart from the sharpening artefacts, I always thought the Z3 pics looks kind of "sterile", or dull, but had no real grounds for it. But I think I know why now! Let me explain.

Many de-noising algorithms nowadays operate mostly in chroma-space, since the chromatic noise is the worst to the eye. And since we all know Sony does some heavy de-noising, it would be interesting to analyze the chroma channels. This can be done by converting the image to YCbCr space, where the image information is stored in 3 channels called: Luminosity, Blueness (Cb, store blue-yellow info), and Redness (Cr, store red-green info). In this space one can operate on color information alone, without affecting luminosity, or the light intensity of the image. A popular and effective de-noising filter is to work with wavelet transform on the chroma channels. Anyway, I was quite shocked when I saw the Z3 images in the blueness and redness channels, as the information is completely destroyed. Here are two 1:1 crops showing this (make sure to open the images in a new view to see them at full res)

This is the price we pay for the low noise images. And this is what causes the Z3 photos to sometimes look "watercolory". An analogy would be that it is a bit like those kids books where you get to color in black and white images, and you use one crayon for a whole tree. Another for the ground etc. In contrast, there is much, much more color information left in the iPhone 5s picture, even though it is only 8MP, as compared to the Z3's 20MP.

But to be fair, it's amazing that the effects of this doesn't show more than they do, and for many it won't be a problem. And I have to point out that I'm not doing this to annoy people. I am simply super disappointed with the Z3 cam, and I am trying to understand what is going on.

I also analyzed some photos taken by [MENTION=3241487]Zanr Zij[/MENTION], who very kindly put lots of photos up comparing the locked bootloader photos to unlocked bootloader ones. Since the unlocking of the bootloader removes some de-noising algorithms, I was curious to see if the chroma channels were intact in those photos:

http://i.imgur.com/ir7gBUd.jpg (side by side)

http://i.imgur.com/y5SYvMG.jpg (locked bootloader)

http://i.imgur.com/FG2Hp5x.jpg (unlocked bootloader)

Original images here: http://xdaforums.com/showpost.php?p=56032545&postcount=167

As you can see, the chroma channels are somewhat better in the unlocked photos, since there is less denoising, presumably, but there still is quite a lot of blurring going on in places. And in the locked bootloader pics, the color information is blurred almost beyond recognition.

So what does all this mean? Most casual users probably need not to worry, if you only intend on keeping the photos on the phone. But for those of us who put higher demands on our gear, it does confirm to some degree the concerns many people have mentioned with "watercolor" photos. And at least now we know more of the origin of the problem. But more worringly it shows that there is still lots of processing going on, even with the DRM keys gone. In Zanr Zijs photos, the cross-hatching is still present in the unlocked bootloader pics. This makes me wonder if the problem might be deep in the firmware, or that there is some processing in hardware that we can't get rid of, and that a RAW photo app might not solve the problem at all. However, there is no way to know for sure, and we'll just have to wait for Android 5.0 to hit our devices and hope for the best.

Here are the full images, decomposed in YCbCr:

http://i.imgur.com/9zPszLX.jpg (Z3, luminosity)

http://i.imgur.com/u1Hxqb9.jpg (Z3, blueness)

http://i.imgur.com/tMJOw1e.jpg (Z3, redness)

http://i.imgur.com/Un6fHPm.jpg (iPhone 5S, luminosity)

http://i.imgur.com/KMnktok.jpg (iPhone 5S, blueness)

http://i.imgur.com/iZkwc2R.jpg (iPhone 5S, redness)

TL;DR

If you look at photos on your mobile only, good for you and carry on! (But I'm selling my phone)