Behind SGS2's Camera - Still Quality

Now the next subject is still image capture on SGS2. Before I go any further, I think now is as good at time as any to talk about what sensors are in the device. Getting to the bottom of this took some poking around, and where I started was the camera firmware. Usually getting what sensors are used in a given device is pretty straightforward - look for driver messages in dmesg when the kernel boots, and then see which ones correspond to cameras. However, on SGS2 the thing is hidden behind a custom ISP that talks over I2C to Exynos, which didn’t lead me much further than just finding out what particular ISP is onboard.

I opened the camera firmware (from /system/etc/firmware ) in a hex editor and fired away. There are number of interesting things which pop up. First up is this:

Softune REALOS/FR is Realtime OS for FR Family, based on micro-ITRON
COPYRIGHT(C) FUJITSU LIMITED 1994-1999

So we know that the ISP is Fujitsu. Then there’s a line like this:

Copyright (c) 2005-2008 by FotoNation. All rights reserved.
Face Detection Library v.1.2.58.7

and finally:

OBED04 Fujitsu M5MOLS

all strewn among a bunch of padded bits and compiled code incorporated into the SGS2’s “camera” firmware. So what’s the real story? Well, SGS2 uses a Fujitsu Milbeaut M–5MO ISP paired with one of two cameras. To find out which camera SGS2 uses, I took a look in Francois’ SGS2 kernel repo under the actual M5MO C driver file. Inside, there’s a line like this inside a function named “m5mo_camera_type_show”:

    if (state->exif.unique_id[1] == 'B') {
    strcpy(type, "SONY_IMX105PQ_M5MOLS");
} else if (state->exif.unique_id[1] == 'C') {
    strcpy(type, "SLSI_S5K3H2YX_M5MOLS");
} else {
    cam_warn("cannot find the matched camera type\n");
    strcpy(type, "SONY_IMX105PQ_M5MOLS");
}

So we now know that inside SGS2 is either a Sony IMX105, or Samsung S5K3H2YX sensor. This is basically the same exact camera lottery situation that the MyTouch 4G Slide is in, as it in fact has the same two exact sensors listed, though F/2.2 optics. Both are basically the same on paper and should offer similar performance - 1/3.2“ size, 1.4µm backside illuminated pixels, and 8.13 MP (3264 x 2448). The front-facing camera uses a Samsung S5K5BAF 2 MP sensor sized 1/5” and with 1.75µm square pixels.

Interestingly enough, I believe I was able to find the actual module which Samsung uses inside the SGS2 on a Samsung fiber optics website, using the Sony IMX105 module. Take note of the appearance of this module, as it’s virtually identical to what I saw inside the device as I’ll show in a moment.

Having two sensor suppliers isn’t anything new, Apple has done it (and will continue to do so), HTC is doing it, and now Samsung is doing it too. With the same on-paper sensor performance and the same autofocus + optical system module, things should all work out and photos should look the same no matter what sensor is inside.

Other specs about the camera module are that EXIF reports an F/2.7 aperture and 4.0 mm focal length. This is a bit odd to me since F/2.8 is on the typical full-stop scale (2*sqrt(2)), and then F/2.4 is a next half-stop, and I’m only aware of IMX105 coming in F/2.4 and 2.8 modules. Just goes to show that sometimes EXIF data is weird. The module is most definitely the F/2.8, f=4.15 mm variant with a 28.1 degree horizontal field of view and 4 plastic aspheric lenses.

As an aside, if this whole system sounds familiar, it’s because the Sony IMX105 module with F/2.4 optics is the oft-rumored camera going into the next iPhone.

So that brings me to the infamous magenta circle issue which numerous people have reported seeing on their SGS2s. The last time we saw this was with the iPhone 4, where a green circle is readily apparent under certain light conditions or when photographing a homogenous color or texture. Some users have reported seeing a similar magenta circle on the SGS2 camera when photographing under similar conditions, so I set out to replicate it.

The closest I can get to the magenta circle

For better or worse, I can’t see the magenta circle on the SGS2 we were given, though I don’t doubt that some devices do show it. It doesn’t take much to extrapolate and come to the conclusion that is in part due to what’s becoming a CMOS lottery - now not only is there a display lottery (like what notebook buyers have been dealing with for a long time), but a CMOS lottery for sensors.

The magenta circle I see on this SGS2 is faint and nowhere near as pronounced as the green iPhone 4 circle, nor the SGS2-captured images I’ve seen online. Further, I haven’t been able to devise a method to tell which of the two possible sensors are inside this particular SGS2. I’ve taken some photos of completely white objects at a variety of focus positions and under different lighting conditions for your own perusal.

We’ve done the usual thing too and taken photos with the SGS2 inside our lightbox test scene, with the lights on and lights off. With the lights on, the SGS2 has a hard time nailing white balance with the test illuminated in auto mode, and in manual mode (set appropriately) it still has the wrong color temperature. This is just a bit unfortunate since otherwise sharpness is excellent, there’s little noise, and little to no chromatic fringing at the edges. I’m very impressed with camera performance here and would encourage viewing those images 1:1.

On the front facing camera, we get performance that looks actually surprisingly good. So good that it could actually pass for rear facing camera quality (resolution notwithstanding) of some previous generation devices.

With the lights out, the SGS2’s single LED flash illuminates the test scene nicely and gives good color temperature. SGS2 also does the right thing and fires up the LED for autofocus in the dark.

Next, we took photos with the SGS2 at the usual test locations, and it’s here that SGS2’s camera really shines. As a reminder, test locations 3, 4, 6, and 7 are the only ones remaining that I can visit, so skip 1, 2, and 5. SGS2 just really has great well-corrected sharpness and performance even out at the edges where aberrations take off, good colors without insane saturation, and great dynamic range.

Finally, I captured a large number of miscellaneous photos with the SGS2’s rear facing camera as well. I think in these real-world scenarios we get to see a better example of the SGS2’s camera performance, which is extremely good among the smartphones we’ve seen so far. Samsung also doesn’t make the mistake of putting the last vertex of the camera system behind a piece of plastic integrated into the battery cover. Instead, the module juts out through the battery cover in a way that doesn’t allow dirt and dust to collect.

Camera UI and Video Quality Inside the SGS2
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  • kreacher - Monday, September 12, 2011 - link

    I was disappointed to see that there is no mention of the screen 's inability to display 24bit gradients while Samsung claims its a screen capable of displaying 16M colors. Reply
  • supercurio - Monday, September 12, 2011 - link

    See my answer for Astri.

    Maybe you only checked a gradient in Web Browser or a specific app that forces 16bit surfaces.
    Each app has the ability to choose how the rendering is done in this regard.
    Internally, the Super AMOLED controller works in much more than 24bit in order to proceed to complex color-space conversions between the a digital frame buffer and an analog, very large dynamic range OLEDs.
    Reply
  • lemmo - Monday, September 12, 2011 - link

    Great review, and incredible detail on the audio quality. Shame the SGS2 has taken a step backwards on audio. Any info on the likely spec for the audio on the Samsung Nexus Prime?

    Also, any recommendations on reviews of best smartphones for audio quality? cheers :)
    Reply
  • supercurio - Monday, September 12, 2011 - link

    Thanks for the feedback!
    I really need it in order to improve next review.

    Organize it differently for better readability, maybe evaluate other aspects as well (like recording)

    I have no info about what's in Nexus Prime but I'd like to :P
    If somebody can send me a report: https://market.android.com/details?id=org.projectv... I'll study it.

    Best devices I know in terms of audio quality:
    - with Voodoo Sound: Nexus S, Galaxy S family, Galaxy Tab 7".
    - with or without Voodoo sound: Asus Transformer
    - soon with Voodoo Sound: Galaxy Tab 10.1 (incredible power stage for the headphone amp)
    - iPhones/iPad: clean DAC but boring headphone amp (unable to drive many cans to adequate levels)

    And.. many I don't know! (yet?)
    Reply
  • lemmo - Wednesday, September 14, 2011 - link

    Thanks supercurio, very helpful. I'll keep looking for more info on the Nexus Prime.

    Shame none of the other phones/tablets you mention have got the right spec for me.

    In practice, do you think the 'average user' will notice the poorer audio quality on the SGS2?
    Reply
  • yellowchilli - Monday, September 12, 2011 - link

    a very very good read thank you
    i've owned the sgs2 since its EU launch..it's interesting to see the slight differences/improvements samsung has put into the US release (e.g. the power button, camera ui)
    Reply
  • mcquade181 - Monday, September 12, 2011 - link

    I've had my SGS2 here in Australia for two months now and on a recent snow trip noticed some deficiencies compared to my friends Nokia N8. We both use the same provider (Telstra 3G on 850MHz):
    1. Whilst travelling there were periods where I completely lost reception whereas the N8 still had a signal and was able to make calls. This suggests that the SGS2 is a bit lacking in cellular sensitivity (and note that the N8 is not all that flash either when compared to the old Nokia N95).
    2. In our snow accomodation I could not get a reliable WiFi signal from the local hotspot whereas the N8 could (it was marginal, but it did work).
    3. Bluetooth on the SGS2 is unreliable with some devices. It keeps disconnecting after a few minutes.

    That said I do like my SGS2 and is better in many other ways to the Nokia N8 - in particular earphone volume and call clarity where the N8 is deficient. Of course android has a much wider selection of available apps than does the Nokia, although surprisingly ALL my favourite apps are also available for the Nokia.

    Regards from down under, Graham Rawolle.
    Reply
  • willstay - Monday, September 12, 2011 - link

    What a coincidence. After two Androids, I actually bought N8 and later sold it to get SGS2. Before Belle, swype was only available in landscape and my must-have apps are not there for Symbian. Reply
  • jcompagner - Tuesday, September 13, 2011 - link

    yes that is the only drawback i also can find of the SGS2..
    Wifi reception is really not up to standards.
    Reply
  • kmmatney - Monday, September 12, 2011 - link

    I'm not happy with the battery tests - they don't show real life usage. I'd still like to know what happens with the battery if you just leave the phone in your pocket for most of the day, or what happens if you leave it in standby overnight. All of my co-workers complain about battery life with their Android phones, and all want to get iPhones the next time around. The batteries seem to drain excessively with the phones doing nothing, and they are often dead when they go to use them. Who cares if you can browse the web for 7 hours or whatever...I just want the phone to be ready to use if its been sitting on my desk for half the day, or if I forget to charge it overnight. This is way more important - at least for someone like me who travels. (actually, I work a lot in wafer fabs around the world, and crappy reception in the fabs often drain battery quickly).

    I guess it will depend on what Apps are installed, and you use push notifications, but it would be useful to have a test where you charge the phone, and then let it sit for 8 hours doing nothing, and then report the battery life. The older Android phones seemed terrible at this, while my iPhone 3GS is great.

    This phone looks awesome, but I would need this information before I would consider buying it.
    Reply

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