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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  • ph00ny - Sunday, September 11, 2011 - link

    Btw you can launch search by holding down the menu button Reply
  • Aloonatic - Sunday, September 11, 2011 - link

    Just curious, but have MS given up on the smartphone market? Or have I just missed out on all the new (or soon to be release) WP7 devices?

    At this rate, I'm just going to have to go with Android and a SGS II, even though I'd love a WP7 phone, but what there is out there are just all old handsets, and I'd have to change carrier to get one now too, as T-Mobile (UK) don't seem to sell them at all any more!?!?!?111!
    Reply
  • dagamer34 - Sunday, September 11, 2011 - link

    If I had to guess, OEMs are working on their new handsets, but want to load them with Windows Phone 7.5, which only RTMed officially a few weeks ago.

    My best guess is we'll see some more phones around October or so, with a Galaxy S II shaped WP7 device.
    Reply
  • Aloonatic - Sunday, September 11, 2011 - link

    Well, October is what I figured too, but... We're already over a week into September and there still aren't any "coming soon" 7.5 devices to be seen anywhere, so I'd be surprised if October (as in the start of October) is anything but wishful thinking.

    It starting to seem like MS just aren't that bothered. Where's the "ooh, look at this coming soon phone" stuff? The SGS 2 like WP7 phone has been mentioned all over the web for months, but there's nothing remotely official, and with only the odd photo shopped image from net dreamers.

    It's a shame, as I'm not a fan of Apple, their products or how they behave. And I've tried Android and been annoyed by their poor updating system, where too many companies have been allowed to let year old hardware languish at the back of the update queue (if it's lucky) while the new devices get all the attention and you're left with juddering menus and in some cases shocking security holes.

    Maybe it's just me, and my problem, for hoping that WP7 might offer a solution to my woes, but MS are just leaving this all waaaaaaayyyyy too late. By the time they get to the party someone will be handing them a bin bag and asking them to help clear up.
    Reply
  • ph00ny - Sunday, September 11, 2011 - link

    What do you mean? It was in the video presentation for the mango announcement month or two ago

    http://www.youtube.com/watch?v=ABO_LyD_SXs

    right around :40 he whips it out of the pocket. I guess he couldn't wait to use it as his daily phone
    Reply
  • Aloonatic - Sunday, September 11, 2011 - link

    Oh, so they have a few units the they showed on a video presentation that who saw exactly?

    Yes, I may have been exaggerating slightly before (and I know that that doesn't stand on geek boards) and we've all (well, a reasonable percentage, as I am sure that at least 1 person reading this hasn't) seen the "leaked" video that no one *wink wink* should video and get out.... But really, there's nothing to be seen here. Those videos are no more proof of a finished product than a concept car at a motor show.

    I'm just disappointed that they hare dragging their feet on this product, and really don't seem to care either.
    Reply
  • ph00ny - Sunday, September 11, 2011 - link

    This was posted on a lot of major tech blog/news sites. As for devices, there are quite a few announced devices but they're all waiting for the mango update Reply
  • vision33r - Monday, September 12, 2011 - link

    Samsung phones are outdated in one quarter. They release small updated features to the same platform.

    The Galaxy line had 4-5 different variant versions within the same year.

    This makes update very difficult for them and also buyer confusion.

    I'll stick with HTC, since Samsung takes forever to fix software and issue timely updates.
    Reply
  • ph00ny - Monday, September 12, 2011 - link

    which device outside of the US carrier branded ones didn't get updates as soon as HTC devices? In fact, which android device manufacturer doesn't release 4-5 different variants within the same year? Reply
  • aegisofrime - Sunday, September 11, 2011 - link

    Had mine here in Singapore for about 3 months now, and you Americans will be joining the party with plenty of custom ROMs and kernels to choose from :)

    So yeah, welcome to the party!

    This forum will probably be your new best friend now:

    http://forum.xda-developers.com/forumdisplay.php?f...
    (Galaxy S II Original Android Development)
    Reply

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