yashsingh1/xdaforums huggingface dataset:
[Galaxy S 4 General] puremind:
Do you have any news on this? The same adaptative brightness mechanism exists on the HTC One, but brightness moves within a more comfortable range between 400cd/m² and 530cd/m². Also it seems th Chrome browser and Stock browser are more affected by this than other browsers, so there is another layer of clipping happening.

It would be helpful if you could find out wich other apps are targeted.
[Galaxy S 4 General] puremind:
The displaymate measurements are exactly consistent with mine.

Oversaturated primaries even in movie mode with green being the most oversturated

Geen push for the white point (white tilted towards green, one notch away from the D65 standard).

Measured peak brightness at 355cd/m²

Measured 100% white brightness at 285cd/m² (which is the measure relevant for web browsing)

This can be seen on the figure below:

Source: http://www.displaymate.com/Gamut_12.html

Note that the auto-brightness peak at 475cd/m² is not relevant for web browsing, as web browsing does not have a 1% average picture level but more of a 90% one instead. I will conduct aut-brightness measurements in the sun for white or near white content likely tomorrow to see if this offers any improvement versus maximum brightness but it is unlikely this will go above 285cd/m²).

So we have to rely on a custom Kernel to fix this (hopefully soon).
[Galaxy S 4 General] puremind:
Barry

You are correct when you mention that this adaptative mechanism has been noted (and in the case of display mate) quantified before. HoweverI don't think people have understood it correclty because Displaymate did not draw the practical conclusions of their own measurements (and in fact leaving these figures uncommented is misleading).

Let me explain and qualify their measurements (which by the way coincide with mine):

The 475cd/m² that you quote is only achievable at an APL level of 1%. An APL of 1 % means a surface of 192*108 (or 144*144) white pixels on a fully back 1080p picture (or equivalent). Not very useful for web browsing.

Web browsing on average has an APL level of 90%

Source: http://www.displaymate.com/Galaxy_S4_ShootOut_1.htm#Table

The peak 1% brightness is therefore not relevant to this discussion. This is also the reason why Brian was not able to reproduce this measurement in his review, as you need a probe with a very small field of view. It never happens in real life situations.

I think what is missing here is an idea of how much brightness gain auto-brightness can add to a real life browsing situatiion (APL of 90%) relative to maximum brightness. I have tested this briefly today and I am pretty sure that it will not go beyond 290cd/m² for bright content (APL of 90% or above).

Autobrightness is the only mode I have not tested yet, because I don't have sunlight available in my room, I will have to wait for more sun to become available. :).
[Galaxy S 4 General] puremind:
Just so everyone understands. To be able to produce 475cd/m² in auto-brightness, the S4's screen needs the APL to be 1% or lower, as pictured below.
[Galaxy S 4 General] DocRambone:
Your measurement is clearly flawed: There is NO clipping in other browsers.

Try it before making faulty statements.

www.youtube.com/watch?v=lki6yx2oXN4
[Galaxy S 4 General] elucid:
I'm having flashbacks to the LCD vs plasma wars at AVS forums :)
[Galaxy S 4 General] puremind:
The video does not show that no clipping is happening. You are comparing two white pictures with throttled brightness and don't see a change. Based on your settings, those should both have around 285cd/m² instead of the peak brightness of 355cd/m² (or in film/sRGB mode, 275cd/m2 instead of 335cd/m²), so the throttle is there in both instances and has adapted brightness in a content-sensitive way.

To be able to see the clipping you need to compare both pictues below in your gallery (1% and 90% white)

The white should be around 40% dimmer on the second picture.
[Galaxy S 4 General] DocRambone:
There is NO change even if i use a picture white smaller white area.(in browser vs wallpaper) so no visible browser throttle on aosp browser at least

Anyway, thanks for the test patterns, they will help me in my work on improving the auto-brightness settings.
[Galaxy S 4 General] puremind:
Extract the files from my ZIP file. Then keep only the following two files in your folder:

90%

5% (5% does measure the same as 1%)

Open the folder with those 2 pictures. Switch back and forth between both pictures (maximum brightness, no auto adjust or power saving). You will see that when you move back to the 90% white, brightness will adjust down by 20% within 500ms.

Chrome and Stock browser will behave the same, just with an extra 20% throttling across the whole brightness range.
[Galaxy S 4 General] DocRambone:
I tried to see any change switch between browser 5% pic to wallpaper 5% pic but cant see any change.
[Galaxy S 4 General] puremind:
Extract the files from my ZIP file. Then keep only the following two files in your folder:

90%

5% (5% does measure the same as 1%)

Open the folder with those 2 pictures. Switch back and forth between both pictures (maximum brightness, no auto adjust or power saving). You will see that when you move back to the 90% white, brightness will adjust down by 20% within 500ms.

Chrome and Stock browser will behave the same, just with more clipping. Here is a depiction of how clipping affects white point brightness at different Average Picture Levels. As we can see, web browsing is the activity that will take the most serious hit, seeing as APL levels for web browsing are in the 80% APL to 90% area. Before 60% APL, the clipping is mild can be considered adaptative. Above 60%, the gamma will be hit and true clipping occurs.

On the second graph, I am showing the percentage clipping versus the 60% APL point (clipping vs. peak brightness is obviously worse).
[Galaxy S 4 General] DocRambone:
Can you do the same mesurement with other browsers?
[Galaxy S 4 General] puremind:
If you used AOSP Browser, then you will not see a difference with the gallery, because both will throttle at an equal level. But actually the 5% level almost has no throttle (see graph above), this is where white should be around the brightest you can get).

What you need to do is compare 5% and 90% or 100% patterns (gallery or AOSP doesn't matter), as those have the most throttling happening to them.

Also to observe the difference between Chrome/Stock browser and another browser (or the gallery or the OS in general), any APL level will work, since the additional throttling is proportional across the full APL spectrum, but this is easier to see with on a pattern with more white surface. Just compare google.de webpage on both browsers...In Chrome or the Stock Browser, this will be an extra 20% dimmer vs AOSP (I tested with Maxthon Browser, but any untampered browser should act the same).
[Galaxy S 4 General] puremind:
With other browsers the throttling will be less i.e. at the same level as the general OS throttling (represented by the second curve on the first graph).
[Galaxy S 4 General] DocRambone:
So over 300 knits with 60% or less white on screen.

A non issue then.
[Galaxy S 4 General] BoneXDA:
So this is a joke? We can close the thread then.
[Galaxy S 4 General] puremind:
As can be seen on the graphs, true clipping will happen above 60%, so only relevant for web browsing, which as an APL between 70% and 90%. For videos, gallery, OS menus and home screens, this will generally not be a non issue (unless in direct sunlight where brightness in excess of 400cd/m² is recommended).

The brightnes clipping really makes out the difference between barely legibile and comfortable viewing. it doesn't prevent you from using the phone.
[Galaxy S 4 General] DocRambone:
Conclusion:

The sunloving users that want surf on the web at the beach (with sunglasses) are better off with a Iphone.

Rest is fine with the s4
[Galaxy S 4 General] puremind:
Depends. For most applications, brightness should be around 300cd/m2. For web browsing it will be between 180cd/m2 and 250cd/m2.

For example, the following browsing screenshot from this very thread , has an APL of 93% and caps at 200cd/m2 (or even 145cd/m2 in the stock browser). If you zoom it on the text portions, the APL increases further and brightness clips at 185cd/m² (or 140cd/m² in the stock browser).

It depends a lot on the content you browse. If you spend a lot of time on xda or other web sites with a lot of text and very few pictures, you get issues. If you just watch Youtube Videos, no problem.

Aren't you all glad I post graphs and pictures in here? :)
[Galaxy S 4 General] DocRambone:
But the main question if its a problem or not.

And the answer: no, its not any problem.

I can sit at my porch in very well lit surroundings and read your posts without any problem.

Thanks for the graphs, you try to make this to an issue where its not.
[Galaxy S 4 General] puremind:
Didn't you say you were using the AOSP browser, though? I am sitting outside underpartly cloudy weaher at 10.30 am where is the sun is still low and reading comfort varies with my position. If I use another browser, reading is relatively comfortable at this time of the day under partly cloudy weather. In Germany, the main review web sites (notebookcheck and notebookjournal) recommend brightness no lower than 300cd/m² or 200cd/m² (perfectly matte screen) for comfortable sun legibility - in every laptop review.

Based on my experience with the S2 (which still measures at 280cd/m² on a full white background) this is about right. In Germany I did not have too many issues, but on vacation in Thailand I was getting pissed off earlier in March and my friend who had the S3 had the same issues.

I just won't be happy with anything worse than the S2 in that regard, I know that for certain (but then the S2's battery life is so much worse). The stock browser brightness is just not acceptable. I haven't started rooting on this device yet, so I can't use AOSP, and the other browsers are not as smooth.

The question is not whether you can read it, you can usually still read it by changing position or protecting from light with your hand, but the question is, is it comfortable and does it become an annoyance? Over here, the weather has been timid at best lately, but the summer will be a different story (not to mention my favourite vacation destinations have more sun).

Anyways I have decided to keep both the S4 and HTC One. The S4 can't control AV Receivers with the remote control app and is only half as bright. I can see the S4 becoming my daily device for its robustness and easy handling, but on vacation or on a sunny day, I think the One will be more comfortable to use (twice as bright for web browsing with very similar reflectance value and battery will last longer at maximum brightness).

It is kind of ironical how the One has got the camera that the S4 should have had (since it fares better under low light!) and vice versa. That would have seggregated both devices to antagonist uses even more. :)
[Galaxy S 4 General] DocRambone:
Not the same as in the shadows, where the s4 is rather bright.

Try another browser is my recommendation for you.
[Galaxy S 4 General] puremind:
Yes I agree in the shadows it should not be an issue with a different browser. It will be an issue if ambient light is very bright though, for example sitting at a pool under partial shadows in a tropical or subtropical location. :)

Sorry this is a bit off topic, but can you recommend a browser that

is as smooth as the stock browser (even though it is not as smooh as on the S2 and S3)

has more than 1 zoom level (the stock browser refuses to zoom closer)

has text reflow for custom zoom levels (like on the HTC One).

I have tried many in the past and was never happy. Maxthon, Opera, Dolphin, etc....Does AOSP meet all of the above conditions?
[Galaxy S 4 General] DocRambone:
Yes, or the cm10 version. The problem can be that you need to root and delete the current browser first.

The attached one is from CM10, try and see if it installs.
[Galaxy S 4 General] puremind:
It says application not installed. I guess I will have to root.
[Galaxy S 4 General] puremind:
OK guys, I have now updated the original post with a graph that contains all of the power saving options. I have now also found that the Chrome/Stock Browser behavior follows exactly the Power Saving mode's behavior, therefore if you are looking to defeat the 25% brightness loss observed in those browsers, this is what you devs should try to deactivate in custom kernels.

Even without any Power Option engaged, white levels on white or near white content will be 15% to 20% below peak brightness (290cd/m² from 355cd/m²)

Auto-Tone will clip whites further above 60% Average Picture Level

Power Saving mainly transposes brightness down by 25%

In Chrome and in the stock browser the Power Saving mode is activated as a default (surely in an attempt to fool battery tests into overestimating number of browsing hours on battery) - and cannot be defeated. It is therefore recommended to switch to another browser (e.g. AOSP) for better outdoor viewing.

I have now also added measurements for the HTC One. This shows that the exact gap between both devices. For Web Browsing the HTC One will be about 70% brigher.
[Galaxy S 4 General] bala_gamer:
found out the reason for brightness throttling in UI, its nothing but the power saving mode samsung is using. Will add a mod to disable it in few mins :)
[Galaxy S 4 General] ap3604:
You guys are both awesome :highfive:

Thanks puremind for the scientific style research and thanks bala_gamer for coming up with a way to disable it :good:
[Galaxy S 4 General] bala_gamer:
here we go :)

http://xdaforums.com/showthread.php?t=2272275
[Galaxy S 4 General] DocRambone:
To see the extra boost in autobrightness you need very well lit conditions.

Even outdoors in cloudy day it will not activate.

But there is hope, the settings can be changed so this extra boost will appear at lower brightness conditions.
[Galaxy S 4 General] puremind:
Funny you talk about this. I just finished measuring the auto-brightness mode. You are right, the boost mode (vs. maximum brightness) will not activate without prolonged exposure to extremely bright light (I had to use my HTC One's flash at close range to simulate this).

Summary

The boost mode offers a 35% brightness gain, however this gain starts to plummet at around 60% APL, which means that the gain for web browsing and Google Maps will only be 5 to 15%

The peak brightness under prolonged sun exposure at 1% APL level is 478cd/m² (displaymate measured this at 475cd/m²). whereas the maximum brightness for pure white ends up at the unboosted level of 383cd/m²

Without Boost Mode, the brightness curve in a birghtly lit environment is exactly the same as the maximum brightness captured in my earlier graph.

The auto brightness -5/+5 radio button has no impact on the maximum brightness achievable - it will go full throttle if it has to. Only brightness at lower ambient light levels is impacted by this fine-tuning...

Hopefully understanding these relationships will help you analyse the Kernel's control points.
[Galaxy S 4 General] DocRambone:
Did you measure the brightness in the browser?

I tested the aosp browser with a full white webpage. (google.com), in direct sunlight its very well readable (tropical climate with high brightness). Both in auto and 100% manual setting

I also tried Note 2, at same spot the S4 is slightly brighter with lower screen reflections.
[Galaxy S 4 General] puremind:
No, all with the gallery to avoid the power mode activation (so essentially this will align with the AOSP browser behavior). The power boost does help (between 5% and 15% improvement for web browsing - depending on the brightness of the content displayed).

Edit: Tested auto-brightness in the Chrome/Stock - there is no Power Saving mode override in auto-brightness, and those browsers even benefit from the Boost Mode.

The power saving 25% reduction only applies at a fixed brightness.
[Galaxy S 4 General] puremind:
Regarding web browsing in particular, I tested in boost mode on several web pages, and white brightness was between 290cd/m2 and 340cd/m² (with picture content). So this confirms my earlier assessment that web browsing typically has an APL between 70% and 90%.

So in a best case scenario, boost mode will yield a +15% boost for web browsing and for a typical web page without pictures this will be more around 10% boost with brightness then around 300cd/m².

I tested this outside and this is legible even if not entirely comfortable.

The HTC One is still 60% brighter overall while having the same reflectance value, so this obviously does add an additional level of comfort.

With 1 hour of bright screen, I lost 15% battery. This is about 6.5 hours of bright screen. Not bad at all. But what will be interesting is how battery is impacted in boost mode.
[Galaxy S 4 General] DocRambone:
Where did you find the APL number for webpages?. A quick check of some larger webpages shows lot less than 80-90%
[Galaxy S 4 General] puremind:
I simply measured the brightness of several web pages in boost mode. I then plotted them on the curve and the corresponding APL reading was 75% to 95%. Typical is 80% to 90%.

The actual brightness is more important than the APL % though, the important message is that for web browsing brightness will rarely be above 310cd/m², zoomed realistically on some some dark picture content on the page, the maximum white I was able to observe tracked at 340cd/m².

Can you give me example of your web pages, so i can measure them? I was looking for an APL analyser, but did not find one (though it seems not too hard to code), so I took the brightness readings insteady to be sure.
[Galaxy S 4 General] DocRambone:
Try http://edition.cnn.com/

Or http://www.anandtech.com/
[Galaxy S 4 General] puremind:
OK will do.

Regarding the APL of videos, games and pictures, I based my APL boundaries with the following literature:

Source: http://journal.smpte.org/content/76/9/924.abstract

Based on this, it does also seem logical that web browsing has a higher APL between 60% and 95%. I will try and find an APL analyser if I can.
[Galaxy S 4 General] puremind:
Ok I did the measurements in boost mode (hardly ever triggered until we can change the threshold through custom Kernel).

Anantech: 330cd/m2 (APL of approx. 73%)

CNN: 318cd/m2 (APL of approx. 75%)

The above may seem like a good result but

This is only a 10%-15% boost vs. maximum brightness (against 35% below 60% APL)

I purposely chose pictures with a high proportion occupied by pictures. As soon as you zoom further on the text and move away from solid pictures, you end up with an APL of 90% to 95% and brightness below 300cd/m², such as this:

Google Results Page: 292cd/m2 (APL of approx. 90%)

A solution would be to display a 1/3 black picture in dual view to reduce the APL further.
[Galaxy S 4 General] puremind:
Deleted
[Galaxy S 4 General] Dblumenkranz:
Interesting loophole

Hello this is my first time posting on xda, but I want to first thank everyone for all the great and informative posts. My first smartphone was actually the iPhone 4s, and less than two weeks ago I got the s4. The error of my ways have now become readily apparent to me. Anyways back to the discussion at hand, I definitely notice the reduction in brightness when opening up samsung's s4 stock browser as well as chrome. This is most evident for me when brightness is set to the highest level manually and switching from the home screen to the browser. The change in intensity can be seen as the page opens (very quickly dulls) and if you hold the home button to view all running apps, right before it shows those apps the browser really increases in brightness for a split second before switching.

So what did I find your wondering. I decided to enable multi window and proceeded to set the brightness to max, then I opened up the stock browser which filled the whole page. Then, using the icons that are found on the left side of the page when the multi window function is enabled I switched to another browser that I think is great. It is called boat browser. Very smooth and clean with interesting gesture functions. Anyways, as I switched pages the brightness which was clearly dimmed when entering the stock browser, remained extremely bright in the boat browser. Now I have no equipment to measure the difference between the intensity between the two but to my eye it appeared to be at least 30% brighter. By the way I opened up the browsers to both google's homepage as well as nytimes. This might work as a good loophole for those that need the extra brightness when using the phone outdoors until those smarter than I can come up with a real solution.

Now keep in mind that I am a complete noob to both android and xda, but I thought I would share this with those who were interested. Also I want to say thank you to puremind for all the great info. I'm a numbers guy and I appreciate when someone uses quantifiable data and figures to prove something, not just opinion. I apologize for being so verbose. Hope this loophole works and helps.
[Galaxy S 4 General] puremind:
Well done. You did better to observe this than many Android experts here. The difference ranges from 30% for pure white to 38% for dark content (for web browsing, which is mainly bright, the brightness gain is 32%!) - very close my friend. :good::good:

The brightness differential that you observe is exactly the difference between the middle line (S4) and the lower line (Power Saving) in the chart below (in the Stock Browser and Chrome, power saving is activated as a default).

Note activating Auto-Brightness defeats the power saving mode in Chrome and the Stock Browser.
[Galaxy S 4 General] puremind:
Even before measuring the screen, 3 weeks ago (26th April), I was making the following statements regarding the screen:

Now 3 weeks later, I am able to support this claim.

Summary:

Viewed directly, the display exhibits a green push in spite of near perfect color temperature

Viewing at an angle reduces green and red and increases blue

The most neutral white balances (Delta E of 2.8) can be obtained by viewing the screen at a 15° angle (you can do the test and notice how the green push disappears!)

The color temperature at this angle is further away from the 6500K standard than for direct viewing

but it is still more neutral

(shows the importance of RGB balance)

The following charts shows the RGB balance, correlated color temperature and Delta E for viewing angles of 0° to 40°.

This is an important lesson: sometimes it is preferrable to calibrate at a somewhat higher color temperature to improve the RGB balance (generally a blue push is less perceptible than a green push). However in this case, Samsung's calibration was most certainly to improve the overall brightness of the screen (green has a stronger luminance than red or blue).
[Galaxy S 4 General] exec99:
So, if I understand correctly: brightness throttling we see in the stock browser is simply a power saving mode that automatically turns on, but we can switch it off in screen settings (right?).

The second thing is white brigthness decrease with the increase of APL and for the moment there is no remedy for it?

BTW Now that we know that brigthness throttling in stock browser can be disabled you should post new side by side images of GS4 and HTC One in high ambient lightning. ;)
[Galaxy S 4 General] gtizon:
So what is the best setting that will balance things out?

Auto birghtness: ON or OFF

What screen mode?

Screen power saving mode: ON or OFF

Auto adjust screen tone: ON or OFF?