Commons:Featured picture candidates/File:Potsdamer Platz, Berlin, 160606, ako (1).jpg

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Voting period is over. Please don't add any new votes.Voting period ends on 10 Jul 2016 at 03:30:23 (UTC)
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Skyscapers at Potsdamer Platz, Berlin at the end of the blue hour

* Support high quality blue hour shot -- Thennicke (talk) 05:45, 1 July 2016 (UTC)  Neutral Significant (even visible in thumbnail) posterisation in the sky on the right half of the image -- Thennicke (talk) 05:48, 1 July 2016 (UTC)[reply]

  •  Comment - I hope you looked at larger sizes than the thumbnail. Where are you seeing it at full size? The only place where a really close inspection might see it, to my eyes, is right above the Bahnhof, but even there, if so, it's very subtle and probably a tradeoff that was necessary to have an exposure that, amazingly, got the buildings in focus and also focused the stars without trails! Larger sizes show a progression of changes in tone that is not apparent in the thumbnail. -- Ikan Kekek (talk) 06:52, 1 July 2016 (UTC)[reply]
  • @Thennicke: Thank you for your comment, Thennicke. It's interesting that you noted some posterization. I've been working on this picture several hours and it nearly drove me crazy because I always saw a lot of posterization in the sky, regardless which settings in LR and PS I've chosen. Then I looked at the same picture on my notebook, my tablet and my phone and found out that no posterization was visible at all. I then asked Hubertl, Diliff and Colin for their opinions before uploading the pictures to Commons. I don't have their answers here right now but I remember that none of them noted a severe posterization. Diliff said a little amount of posterization was visible and told me to add some noise to the picture to avoid posterization caused by the JPG-compression. I followed that advice. I really don't know what else I should do. I believe that in the end the quality of the picture might differ depending on which screen you're using to look at it. Maybe I'm wrong but I can't explain that phenomenon otherwise. My skills in post processing aren't that good and I'll be happy if anybody else could give me a hint on how I could even more improve the picture. BTW: Do you see the same issue on the other two pictures of the series? And P.S.: Of course the risk of getting posterization is much higher in the thumbnail than on the larger version because the thumbnail is being compressed much more. --Code (talk) 07:41, 1 July 2016 (UTC)[reply]
  • It's impossible to judge the posterisation from a thumbnail, since the thumbnail has higher JPG compression and sharpening and is created by Imagemagick on the Mediawiki server. The thumbnail is just an indication of what the full size image looks like - it is not an exact replica of it. Also, the sky has a very subtle gradient and this does sometimes cause posterisation problems that are difficult to solve, but often posterisation does not actually exist in the image itself, it's introduced by monitors with low bit depth or by monitor profiles. There is a small amount of actual posterisation but I know from experience that it's very difficult to eliminate in deep blue skies where there is limited sensor information in that range. Canon sensors are sadly inferior in that regard. The best way to avoid it is to shoot HDR or bracketed exposures, and I understand that this is not an HDR image - it is a single exposure. Tone mapping isn't always the best solution though. A common recommendation is to 'expose to the right' (of the exposure histogram). This is because the sensor contains more usable information at the brighter end. However, exposing to the right (maximising the amount information contained at the overexposed end of the RAW file right up to the point where it begins to result in blown highlights) means the photo usually looks too bright, and it then has to be underexposed again in post. This has the effect of giving you lower overall image noise and a greater ability to dig into the shadow detail. I think this image may also have benefited from a second 'overexposed' image which Code could have used the sky from, and it probably would have contained less posterisation. He could have then darkened the sky to match the 'actual' sky visible in this image. It's messy and not always easy to do, but with limited dynamic range in a Canon sensor, it's sometimes necessary. Having said all this, I don't think the posterisation is that bad. It's there, but it's not enough to worry me. Diliff (talk) 08:32, 1 July 2016 (UTC)[reply]
  • If you see some posterization, depends on which monitor you are looking at. On my better one (Iiyama ProLite) it´s almost unvisible - it´s sligthly visible on the other, both are "just" FullHD. I´m interested how it looks on a 5K monitor, so I´ll ask Johann. To say, that it is visible even on the thumbnail, it´s completely wrong, it´s visible BECAUSE of the compression of the thumbnail. But David already explained it very profound. Also Uwe may be asked (Eizo). --Hubertl 09:40, 1 July 2016 (UTC)[reply]
  • Okay, sorry for the bit about the thumbnail. What I'm seeing is significant in the full-sized image though, so it is probably just my monitor, as you've all mentioned. I don't have my desktop computer with me here so I'll stay as neutral for now, because it's impossible for me to judge with such a rubbish screen. It seems like an excellent image otherwise, of course, and I have no doubt you've done your best to reduce posterisation. -- Thennicke (talk) 07:33, 2 July 2016 (UTC)[reply]
Confirmed results:
Result: 17 support, 0 oppose, 1 neutral → featured. /A.Savin 01:06, 7 July 2016 (UTC)[reply]
This image will be added to the FP gallery: Places/Architecture/Cityscapes
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