What the iPhone XS and iPhone XS Max are really doing to your selfies

Posted:
in iPhone edited October 2018
You may have heard some talk about the so-called and poorly-named "Beautygate," where users are claiming Apple's new iPhone XS and XS Max are applying overly-aggressive skin smoothing algorithms on photos taken with the selfie camera, resulting in fake-looking or doctored images. Let's talk about what's actually happening behind the scenes.

iPhone XS low light selfie


With the new iPhone XS and XS Max, Apple introduced a brand new feature called Smart HDR. The new camera mode is designed to increase dynamic range, which is basically the difference between the darkest and lightest tones that a camera can capture.





In our iPhone X vs XS Max Photo comparison, you can see how far Smart HDR seriously increases the dynamic range on the XS Max.




Comparing similar photos taken on the iPhone X and iPhone XS Max, the X's image shows the face and body of the subject are properly exposed, but the highlights in the background are blown out, which means they're so bright that the details, including the colors, are lost.

On the XS Max, all of the details and texture are visible, and the colors are accurately reproduced. Not only that, but in an examination of the shadows, the areas appear brighter and with more detail.

Turning to the pants on each image, it appears like there's a smoothing effect being applied on the XS Max.




If you look at a selfie photo taken in low light, the effect is even more pronounced. There's two main reasons why this is happening, and they're both related to Apple's new Smart HDR feature.

How Smart HDR works

With a regular HDR photo on last year's iPhone X, the camera will snap three photos, taking one exposed for the face, one for the highlights and one for the shadows. It then blends the best parts of those images into one photo.




Professional photographers sometimes reproduce the technique and manually blend images together in a program like Adobe Lightroom, resulting in a photo with incredible detail and dynamic range.




With Apple's new Smart HDR, it all starts with something Apple calls "zero shutter lag." Basically, whenever your camera app is open, the A12 Bionic processor is constantly shooting a 4 frame buffer. It's effectively taking photos over and over again, very quickly, then holding the last 4 frames taken in the system memory without actually saving them to your camera roll.

When you actually do hit the shutter button, you get a photo instantly, since it grabs one of the frames from the buffer. Not only that, but the A12 Bionic also captures a variety of frames at different exposures at the same time, just like regular HDR.

It then analyzes and merges the best frames together into one photo, which has seriously great dynamic range.

All of this has to happen very quickly, and it's all down to the new front-facing and rear-facing sensors. The new sensors most likely have increased readout speed, making it quicker to capture those frames.

The ability to shoot 1080P at 60 frames per second on the front-facing camera is evidence of a new sensor with a faster readout. This is why Apple probably won't give the iPhone X Smart HDR in a future software update.

However, there's another limitation: shutter speed, which is basically the amount of time the camera shutters open to allow light into the sensor. With a very fast shutter speed, less light has a chance to get into the sensor.




Since Apple's new Smart HDR requires everything to happen very quickly, the shutter speed needs to be faster, so as not to slow down the process. Due to this, less light gets into the sensor, which can hamper brightness in the image.

To compensate, the camera increases the ISO, which basically dictates how sensitive the sensor is to light. A consequence of increasing system ISO is that it also increases noise.

Credit: Photography Life
Credit: Photography Life


According to a deep-dive into the new iPhone XS camera system, Halide developer Sebastiaan de With discovered the new iPhone appears to favor fast shutter speeds and higher ISO levels. He believes the behavior is linked to capturing the best possible content for Smart HDR processing, even when the feature is not enabled.

In bright sunlight, users won't notice much of a difference since the image may already be perfectly exposed. In a low light scenario, the ISO needs to be turned up pretty high, which introduces a lot of noise.




To compensate, Apple adds noise reduction processing to the images.




The most common drawback to noise reduction is that details start to lose their sharpness and look soft, basically what is being called skin smoothing.




The reason the skin smoothing effect is more noticeable on the front-facing camera is because the sensor is a lot smaller than the one on the rear, so even less light has a chance to get in.




So no, Apple isn't applying a beauty filter. The smoothed out areas are mostly due to added noise reduction introduced as a result of new camera behaviors likely related to the Smart HDR feature. If we compare a low-light photo from the XS Max to something like the Galaxy Note 9, we'll see that the Note 9 is applying noise reduction as well, leading to a similar beauty mode effect.


Pronouncement

This only explains half of the overall beautygate puzzle. The second half deals with why the effect is even more pronounced.

As Smart HDR is taking more frames at different exposures and combining them, it's able to have more high-light and low-light detail than ever before. However, when merging those images together, the photo becomes more balanced and there is an overall decrease in contrast throughout the whole image.




It works the same when shooting video on a professional camera. When filming in a flat profile, there's initially a lot less contrast, but it holds a lot more detail in both the shadows and highlights.




After adding some contrast back in, the image looks just as sharp and has better dynamic range.




Looking at photos from the iPhone X and the XS Max, it seems as though the iPhone X's photo is sharper, but if you look closely, it's actually not. The reason the photo looks sharper is because it has more contrast.




Contrast is basically the difference in brightness between objects in a photo, and in this example, the bottom half isn't any sharper, it just has added contrast.




A similar effect was found when comparing the XS Max to the Samsung Galaxy Note 9. The photos and video on the XS Max lacked contrast and looked less sharp compared to the Note 9.




In this selfie comparison, the iPhone X's image has more contrast, making it look more detailed.




The iPhone XS Max's lack of contrast makes it look like there's some kind of skin smoothing effect being applied, but if we add some contrast back in, that effect starts to melt away.




So it's actually the lack on contrast that makes it seem like the skin is softer when in a well-lit environment.

Changes are possible

Technically, Apple would just need to tweak the software to resolve the issue if it so chooses. That will take care of the contrast part of the puzzle, but as for noise reduction, that's something that happens on basically every phone's selfie camera in low-light conditions.

As for Smart HDR, Apple can tune the feature to make it work slower, allowing the shutter to stay open a bit longer, but of course, that'll reduce the dynamic range performance on the XS and XS Max' new cameras.
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Comments

  • Reply 1 of 26
    netroxnetrox Posts: 716member
    The dynamic range has been supported since 6S but Xs has a better bigger sensor thus better quality overall.
  • Reply 2 of 26
    grifmxgrifmx Posts: 84member
    well explained.
    mike54wlym
  • Reply 3 of 26
    k2kwk2kw Posts: 1,694member
    Thanks.

    Do we know who makes the camera sensor?

    theVerge said they thought it was Samsung and that was why the camera this year was producing images similar to Samsung’s camera from mast year.(I’m not saying Samsung is better than Appple)
  • Reply 4 of 26
    Taking Selfies?

    Oh how quaint.... :smile:  :)

    As for HDR, I use Photoshop or Aurora to produce the end results. I can't imagine doing this sort of editing on a small screen. There is far too much subtlety for the small screen.
  • Reply 5 of 26
    StrangeDaysStrangeDays Posts: 7,071member
    netrox said:
    The dynamic range has been supported since 6S but Xs has a better bigger sensor thus better quality overall.
    The computational stuff in Xs was not present in the X and prior.

    iPhone XS: Why It’s A Whole New Camera

    https://blog.halide.cam/iphone-xs-why-its-a-whole-new-camera-ddf9780d714c
  • Reply 6 of 26
    Hey AI:

    Glad you’re giving Max Y. work here, he does a great job. But you should give him credit. This has his fingerprints (and face) all over it. Is Daniel too much of a attention hog to use real bylines for other writers?  

    Big step up from most writing in this site.
    mike542old4fun
  • Reply 7 of 26
    sandorsandor Posts: 505member
    Taking Selfies?

    Oh how quaint.... :smile:  :)

    As for HDR, I use Photoshop or Aurora to produce the end results. I can't imagine doing this sort of editing on a small screen. There is far too much subtlety for the small screen.
    The iPhones create the HDR image on the fly, no user intervention necessary.

    Eventually, once 16 bit sensors become mainstream, and we have a great Dmax in a single image, the hack of HDR will be moot. For now it is in the range of the Hassey with 16 bit * 14 stops dynamic range.

    The majority being stuck with 8 bit JPG currently doesn't help either :)
  • Reply 8 of 26
    Somebody else going to post a link to this article on Lewis Hilsenteger's Twitter/YouTube page, or shall I do it? 😄
  • Reply 9 of 26
    dewmedewme Posts: 1,988member
    Nicely done article. I've seen essentially the same effect when using Aurora HDR 2018 and Noiseless in Photos when my photos have imperfect lighting and limited dynamic range. Turning up the knobs on HDR introduces noise so then I run the photo through Noiseless and I typically end up with a photo very similar to what the iPhone is doing in the above scenarios. I think Apple has done a pretty good job for folks who want consistently pleasing photos with point & shoot simplicity. For those willing to put more thought and control into what they are doing, apps like Halide Camera are there to give you back near total control. Win-win. 
  • Reply 10 of 26
    mike54mike54 Posts: 310member
    Very good article Vadim. Well done.
    As someone mentioned above (JessiReturns) its a 'big step up from most writing on this site.'


    edited October 2018 wlym2old4fun
  • Reply 11 of 26
    HuhHuh Posts: 1unconfirmed, member
    Nice article but how do you explain away the smoothing with smart hdr off? The chinese phones have had this heavy noise reduction for years- they call it beauty mode . I guess you call it a new feature?
    edited October 2018
  • Reply 12 of 26
    silvergold84silvergold84 Posts: 62unconfirmed, member
    in the android world the filters are real . Selfies appear without many details and very smooth skin. But you can see the photos of Xs Max give back exactly what the eye see. Natural, realistic pictures . No color errors. All the details are in the photos. I have the new Xs and it’s awesome. I did take photos that are incredible for a smartphone . It’s true. A new era for a mobile camera ,like Apple said. 
  • Reply 13 of 26
    Huh said:
    Nice article but how do you explain away the smoothing with smart hdr off? The chinese phones have had this heavy noise reduction for years- they call it beauty mode . I guess you call it a new feature?
    I see you're new here, but this was talked about in the video. Snapchat and other apps have been doing it longer than any cheap Chinese phones have, so... Nobody is calling it a new "feature."
  • Reply 14 of 26
    macplusplusmacplusplus Posts: 1,595member
    Huh said:
    Nice article but how do you explain away the smoothing with smart hdr off? The chinese phones have had this heavy noise reduction for years- they call it beauty mode . I guess you call it a new feature?
    What you call “smoothing” is actually the dismissal of the artificial local contrast introduced by the camera/processing. All old digital photos and most DVD videos include that artefact, a light+dark outline around shapes, similar to the Unsharp Mask filter. This is so widespread that it apparently shaped our understanding of a good photo. As soon as we begin to notice “granularity” (actually mostly artificial noise due to local contrast) in a photo we call it good photo. Enlarge an iPhone photo as much as you can, you’ll never see that light+dark outline around shapes. Maybe this is the first time we get a true digital representation of the scene.
  • Reply 15 of 26
    Would be nice to see a camera review where the reviewer took photos with similar subjects to what normal/consumers shoot - like group shots in really bad lighting, blowing out candles in bad lighting, children that won’t stop moving etc. 
  • Reply 16 of 26
    StrangeDaysStrangeDays Posts: 7,071member
    Hey AI:

    Glad you’re giving Max Y. work here, he does a great job. But you should give him credit. This has his fingerprints (and face) all over it. Is Daniel too much of a attention hog to use real bylines for other writers?  

    Big step up from most writing in this site.
    They use bylines all the time. DED is an opinion columnist and has nothing to do with it. 
  • Reply 17 of 26
    StrangeDaysStrangeDays Posts: 7,071member

    Huh said:
    Nice article but how do you explain away the smoothing with smart hdr off? The chinese phones have had this heavy noise reduction for years- they call it beauty mode . I guess you call it a new feature?
    You’re quite wrong. This photo app developer has written all about it, and his own camera app doesn’t use Smart HDR, resulting in noisy RAWs, then applies his own effects. The XS doesn’t apply the noise reduction (“smoothing”) when Smart HDR is disabled.

     https://blog.halide.cam/iphone-xs-why-its-a-whole-new-camera-ddf9780d714c
    edited October 2018
  • Reply 18 of 26
    Mike WuertheleMike Wuerthele Posts: 4,339administrator
    Hey AI:

    Glad you’re giving Max Y. work here, he does a great job. But you should give him credit. This has his fingerprints (and face) all over it. Is Daniel too much of a attention hog to use real bylines for other writers?  

    Big step up from most writing in this site.
    FTA:


    edited October 2018 king editor the grate
  • Reply 19 of 26
    Mike WuertheleMike Wuerthele Posts: 4,339administrator

    Nigel_S said:
    Somebody else going to post a link to this article on Lewis Hilsenteger's Twitter/YouTube page, or shall I do it? 😄
    We did before on the previous article about it.
  • Reply 20 of 26
    macplusplusmacplusplus Posts: 1,595member

    Huh said:
    Nice article but how do you explain away the smoothing with smart hdr off? The chinese phones have had this heavy noise reduction for years- they call it beauty mode . I guess you call it a new feature?
    You’re quite wrong. This photo app developer has written all about it, and his own camera app doesn’t use Smart HDR, resulting in noisy RAWs, then applies his own effects. The XS doesn’t apply the noise reduction (“smoothing”) when Smart HDR is disabled.

     https://blog.halide.cam/iphone-xs-why-its-a-whole-new-camera-ddf9780d714c
    I have a gut feeling that the explanations given by that developer should be taken with a grain of salt.

    What doesn't fit is his "high ISO introduces a lot of noise then Apple smooths the image to remove that noise" claim. I don't think he's talking based on a white paper from Apple, those are just his interpretations of the photos. That doesn't fit because with such a powerful CPU, neural engine and a brand new image signal processor, the noise issue might not have such a weight as to dramatically affect underlying algorithms and the resulting photos. Besides, with a Apple-developed image signal processor talking about noise makes no sense at all.

    "The image signal processor features a refined depth engine, which captures extraordinary detail in Portrait mode. And with Smart HDR, you’ll notice far greater dynamic range in your photos." 
    https://www.apple.com/iphone-xs/a12-bionic/

    There are no noise and no image smoothing at all, IMHO. Enlarge the XS photos to the max and watch how pixels are aligned at the borders. There are no fuzziness, no stray pixels, no "unsharp mask" outline (local contrast). All pixels align perfectly and smoothly the most natural way, as if drawn by an artistic hand, which is nothing more than the image signal processor of A12.
    edited October 2018
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