[POLL] Black clipping / black crush

---

I wanted to branch out from the other thread and actually do a poll to see how many people are experiencing this problem, and how severely. In the other thread (http://forum.xda-developers.com/show....php?t=1515299), several people claim that their copies are absolutely perfect and show no signs of black crush. If you indeed have a "good" screen, your feedback will be incredibly valuable. Please post pictures of your phone, if you do the test below and the blacks display correctly!

The reason that most of us are seeing "black crush" or ugly blockiness in dark areas in videos and photos is that these artifacts are present in the source material. Blocky patterns are a result of compression, and are most noticeable at the extreme ends of the dynamic range, where there is the least amount of detail. So if these compression artifacts are present in the source material, why do we not see it on other devices? It is because most other displays are properly calibrated to gradually gradate dark tones from dark gray to black. In other words, on a properly calibrated display, the color #000000 (black, or RGB 0,0,0) is virtually in distinguishable from #010101 (RGB 1,1,1). In fact, it is hard to tell a difference until #050505 (RGB 5,5,5). Therefore, most of the clipping that occurs as a result of compression artifacts is hidden. However, with the Note, #010101 is very much distinguishable from #000000. Dark tones are too bright, and we're able to see clearly until #010101. Instead of gradually moving to black, at #000000, it drops off a cliff. This is why we see such a dramatic different between the darkest grays and blacks, and why this black crush issue is so noticeable.

The side effect of having grays that are too bright is that when watching Blu-ray quality HD video, the dark areas look washed out, and the picture lacks "punch". High quality video that is properly encoded very rarely have pure blacks (to avoid clipping). As a result, dark scenes appear too bright on our phones.

The method to test is with a gamma test pattern, which I have attached. Download QuickPic from Market/Play (free). Go to Settings -> Viewer, and check the box for 32-bit render. Then, download the attached .png file, and view it in full screen in QuickPic. Make sure to do this in a DARK room!

Each box with a number has a corresponding RGB value. For example, the box with the number 1 is RGB 1,1,1, and so on. Load it on your Note and report back the smallest number that you are able to see. Also, does it gradually go to black, or does it just abruptly go to black without a smooth transition?

Last week, I went to two AT&T stores, and tested every display model with this method. Even with the bright store lights, it was possible to see box #1 on every phone. Repeated the test on an iPad 2, Galaxy Tab 10.1, and Skyrocket. The iPad was too dark, as the entire left side of the test picture is unreadable. On the Galaxy Tab, I could see box #7 or so. The Skyrocket showed a similar problem to the Note, as it seemed to abruptly transition to black. However, it was still a bit smoother than the Note, and box #4 was the smallest I could see.

Here's a picture of the test on my phone. The right side is the test image itself, so you can see how it is supposed to look like on your computer screen. Compare this with what you see on your phones.

I can see all the numbers on the left side in a dark bathroom only black is the part above the number 1. I'm thinking of exchanging my note...



Sent from my SAMSUNG-SGH-I717 using Tapatalk 2 Beta-2

If i understand correctly its not hardware then?

Sent from my SAMSUNG-SGH-I717 using XDA

I just updated the YouTube app and watched all those videos that were linked in the other thread and it actually seems to have made a difference. Looks a lot better. Maybe it was just bad quality before?

Sent from my SAMSUNG-SGH-I717 using XDA

Originally Posted by Deviance

I can see all the numbers on the left side in a dark bathroom only black is the part above the number 1. I'm thinking of exchanging my note...

Sent from my SAMSUNG-SGH-I717 using Tapatalk 2 Beta-2

I'm not sure exchanging it will do anything. Like I said, I have tried 5 different display models. I have also had 2 Notes myself, so that's 7 copies total and they all exhibit this issue. When people watch a video, like starfield 720p and claim that it's "perfect", that can be subjective. But if you're able to clearly see the box with the number 1, and is dramatically different from the black box above it, then you can objectively conclude that the device has a problem. If you go exchange it, and get lucky, report back. One of the things I want to find out is what percentage of Notes (if any) display dark tones correctly.

Originally Posted by SkizzMcNizz

If i understand correctly its not hardware then?

Sent from my SAMSUNG-SGH-I717 using XDA

I have no idea if it is hardware or not. It could be something as simple as an incorrect gamma curve, or it could be caused by a hardware limitation. If you want to get more into the technical stuff, you can refer to Supercurio's thread here: http://forum.xda-developers.com/show....php?t=1430847

Originally Posted by tenderchkn

I'm not sure exchanging it will do anything. Like I said, I have tried 5 different display models. I have also had 2 Notes myself, so that's 7 copies total and they all exhibit this issue. When people watch a video, like starfield 720p and claim that it's "perfect", that can be subjective. But if you're able to clearly see the box with the number 1, and is dramatically different from the black box above it, then you can objectively conclude that the device has a problem. If you go exchange it, and get lucky, report back. One of the things I want to find out is what percentage of Notes (if any) display dark tones correctly.



I have no idea if it is hardware or not. It could be something as simple as an incorrect gamma curve, or it could be caused by a hardware limitation. If you want to get more into the technical stuff, you can refer to Supercurio's thread here: http://forum.xda-developers.com/show....php?t=1430847

Thanks. I don't want to return my phone to best buy again for a 5th time. I think I've shopped there for the last time. I had quality control problems with them with the galaxy tab also. Im gonna see if at&t will carry out my exchange this.time

Sent from my SAMSUNG-SGH-I717 using XDA

Originally Posted by SkizzMcNizz

I just updated the YouTube app and watched all those videos that were linked in the other thread and it actually seems to have made a difference. Looks a lot better. Maybe it was just bad quality before?

Sent from my SAMSUNG-SGH-I717 using XDA

Make sure to test with the attached .png file. Like I said, watching a video can be subjective. If you open up the test image in full screen and can see all the way to the number 1, then the videos may "look" better, but the underlying problem still exists.

Originally Posted by tenderchkn

I'm not sure exchanging it will do anything. Like I said, I have tried 5 different display models. I have also had 2 Notes myself, so that's 7 copies total and they all exhibit this issue. When people watch a video, like starfield 720p and claim that it's "perfect", that can be subjective. But if you're able to clearly see the box with the number 1, and is dramatically different from the black box above it, then you can objectively conclude that the device has a problem. If you go exchange it, and get lucky, report back. One of the things I want to find out is what percentage of Notes (if any) display dark tones correctly.

Thanks for your input. I am going to show this to ATT and see if they can let me test the note's and hope to find one that is better. There has been some luck with others in the other threads posted. I hope I can get one that is better or Samsung fixes the problems. I saw the clipping problem for the first time on a 2gig 720p copy of Killer Elite and I was so mad that my new phone has this problem.

****, I never realized an issue, but I did the test and it looks like the picture of your phone. I can see all the numbers on the left.

Mine looks just like yours... so I guess I am severe

Test does look quite different depending on how much you turn up the brightness, but either way I can see all the numbers.

Edit: but no way in hell am I returning it for a model that runs hot, is laggy, purple blotches, or whatever other issues people complain about around here.