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Paulo Calafate
Member
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# Posted: 8 Dec 06 01:31
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There are something that I can not explain with the blue of the skies in the digital systems (cameras and scanners), mainly if the area is big enough, without much detail (clouds), that is the “breaking” of the pixels resulting in an inaesthetic and not natural sky. I think this phenomenon is less perceivable in the DSLR cameras. But with some work in Photoshop we can easily restore the homogeneous blue color of our sky making use of selections, feather, gradient paint and blur filter (surface and gaussian).
To illustrate this I chose some pics of 4 Woophy members where this aspect is visible – I hope you don’t mind about their usage.
original by Akbar (you must view in the large format)
with photoshop work
original by Bruha (view in large format)
with photoshop work
original by Jeroen Krol (view in large format)
with photoshop work
original by Ortho158 - a scanned image (view in large format)
with photoshop work
original by Ortho158 - a scanned image (view in large format)
in this one the dominant color sky is not the blue and the situation is different
with photoshop work - and in the last one, beside the sky, I made some other small adjustments, because I like this pic very much.
In my opinion, the sky that we see does not have the pixels produced for the digital cameras. These devices modify the reality, so if the photoshop can correct it why not to use?
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Marcos
Moderator
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# Posted: 8 Dec 06 01:38
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Hello Paulo, interesting point ! I always think about this but I have never tried to correct it. :-)
In the first picture, the difference is very clear, is the picture where the difference is clearer.
I believe it would be very good if you tell us how did you do it. Very important. :-)
Greetings !
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bruha
Member
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# Posted: 8 Dec 06 09:10 - Edited by: bruha
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Hallo Paulo - Interesting point but I do think that you have to take into account the location of the photo.
Parts of NZ often has an incredibly blue sky at any time of the year.
However Auckland City being situated on a narrow isthmus of land between two huge oceans often has a sky similar to the sky behind the rather gorgeous lady and sometimes very grey looking.
The sky in my photo of Thorne's Bay was pretty well the colour of the day.
However Sydney has a sky so blue that it hurts. I have never felt the need to adjust the colour of the sky in my photos.
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Lionel Lafay
Member
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# Posted: 8 Dec 06 09:30
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Hi Woophians...
@bruha : Of course, I don't want to hurt you but I think you didn't understand the Paulo's point of view. He didn't change the colors of your picture, he has just reduced the noise that a lot of digital cameras produce in deep blue skies. This noise depends on the digital image sensor and level of jpeg compression. He didn't have bad intentions.
@Paulo : You made a very good job. It's very impressive with Akbar's picture but I think you should ask to each member before posting their pics here. Personally, I'd like to see what you could do with my pictures. Just let me know if you are interested in...
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ortho158
Member
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# Posted: 8 Dec 06 11:01
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Thanks Paulo. After scanning, I process the pic in (a competitor of) Photoshop and, among other things, I sharpen the pic. And I generally exclude the sky from the sharpening, because it's much too visible. I guess that I would simply have to do some unsharpening on the sky now. Right?
By the way, I'm flattered that you took two of my pics for your demonstration (and you have the warm thanks from my wife). alain
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Aline
Member
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# Posted: 8 Dec 06 12:30
Reply
Thanks Paulofor opening a forum on this topic.
On my side, I use Paint Shop Pro, not Photoshop. It exists on Paint Shop Pro several tools for correct the "digital" noise. And I usually use it on the all picture, not on only a part.
So I don't spent time selecting part of the picture, but I often spent time for choose the right setup of the correction !
I don't know if it exists the same on PhotoShop. But I guess it is.
So my question is : Is it better to use your technic, Paulo ? and if yes, please, could you explain me in detail why ?
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Paulo Calafate
Member
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# Posted: 8 Dec 06 12:44
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@Bruha - the only thing I adjust in this photos was the noise that the digital cameras produce and that are particularly visible in the skies. I tried not to modify the original color. If you noted some color alteration I think this is because when we open edit and save a pic the photoshop can slightly modify its colors.
@ Lionel Lafay - thank you for your explanation about the origin of the undesirable noise in the blue skies. I do the same work with 3 of your pics:
original by Lionel Lafay
with photoshop edition
original by Lionel Lafay
with photoshop edition
original by Lionel Lafay
with photoshop edition
@ Ortho158 - thanks to you and your wife
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Akbar
Member
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# Posted: 8 Dec 06 13:04
Reply
Hi Paulo,
Just had a look at the pic by me, that you used. The difference is great. So, I'll have to start using photoshop afterall I think. And offcourse I don't mind you using my pic as an example.
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Lionel Lafay
Member
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# Posted: 8 Dec 06 13:42
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Thank you Paulo,
The results on my pictures seem to be very good.
Yes I said "seem" because I am now at job and my screen display is not very performant. I will have a look tonight to appreciate your work better.
About the technic now, did you create a photoshop script to work quickly ?
Do you know some free tools like NeatImage (unfortunately limited to 1024x1024 px in the free version) to do this job automatically ?
I will put the links here when I will have more time...
Greetings
Lionel
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ortho158
Member
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# Posted: 8 Dec 06 17:23
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@Lionel
I have the free version of Neat Image (v5), and it is not all limited to 1024x1024 px. In other words, it processes my 8Mpx pics without problem. As far as I know, the main limitation of the free version (as far as I am concerned) is related to its batch capability: no more than 2 pics in the batch queue. For a detailed comparison of the versions, see
http://www.neatimage.com/featuremap.html
Now, NeatImage alone can't do the trick, as it cannot select a part of the pic to be de-noised. You have to combine the full denoised pic with the original one, in Photoshop.
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ortho158
Member
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# Posted: 8 Dec 06 17:58
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@paulo
I tried myself, with NeatImage. I did not do what I said just above: I de-noised the full pic. Here is the result:
Again, you have to view the large version.
As always, picture manipulation is a matter of trade-offs. In your version, the sky is more de-noised than in mine; on the other hand, I prefer the clouds in my version.
Now, we have both a problem! You made an excellent suggestion, and I would like to replace the old version of my pic by the new one. But, if I do that, you lose the pic that you used as example! OK if I do it in, let"s say, 2 weeks?
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Paulo Calafate
Member
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# Posted: 8 Dec 06 17:59
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@ Aline
This noise is specific on large blue surfaces like skies, as say Lionel Lafay, its a problem with some digital image sensor and level of jpeg compression. So, in subjects with texture and detail the problem is not visible and this way we don't need to make any adjustment in that parts. It´s so easy to select the blue sky with the Magic Wand Tool in photoshop. With some other tools (Eraser, History Brush, etc.) I spend only about 1 minute correcting the sky. The last step is to apply the surface blur filter of photoshop playing with its Radius and Threshold slide-bars to get the desired result.
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Paulo Calafate
Member
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# Posted: 8 Dec 06 18:12
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@Orto158
In your pics I only selected and worked the blue sky. The clouds, as the remaining image, was untouchable. You applied a de-noise filter to the whole image. It's different, but I like the result and the filter quality of the NeatImage.
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Aline
Member
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# Posted: 8 Dec 06 18:30
Reply
Thank you Paulo. If I understand you well, it is as convenient to do as correct noise on entire pictures, and more accurate when the noise is specifically located on the sky.
I have to look better on my own pictures ! I often noticed and corrected noise on all picture (as night pictures), but never just on a sky, for instance.
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ortho158
Member
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# Posted: 8 Dec 06 18:32
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@Paulo, I see what you mean about 'not retouching the clouds', but there are parts of the image (the wisps of clouds in the top middle-right) where you can see a difference: some of those wisps have disappeared (or be attenuated). I think that it is unavoidable in this case, as there is no clear separation between sky and clouds in these parts.
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Paulo Calafate
Member
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# Posted: 8 Dec 06 19:09
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@Ortho158
You have reason. I think that with scanned pics your solution is better than mine. To obtain a good result with your pic I must spend more time doing more accurate selections and working very well with the feather option.
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Jeroen Krol
Member
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# Posted: 8 Dec 06 19:24
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Paulo,
in my image (the 3rd image, with the people walking in the beach) the original version has a very clear sky with minimal noise. In this (Woophy) version the 'jpeg'-compression causes this effect.
Nonetheless, your postprocessing does have a great effect.
Have a nice day,
Jeroen
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bruha
Member
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# Posted: 8 Dec 06 22:08
Reply
No guys, I wasn't upset, however I did miss the point completely
but I am so pleased that you have opened this subject up.
I had no idea about the noise producing problem in digital comeras.
This is the area of Woophy that I enjoy as it is a great learning curve for me.
Thank you all for sharing your knowledge with me.
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Lionel Lafay
Member
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# Posted: 9 Dec 06 14:33 - Edited by: Lionel Lafay
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@Ortho158
Thank you for your clear councils about Neat Image. You're right, the free version is not limited to 1024x1024 px pictures indeed.
In fact, it's the free version of Photoshop's plugin Neat Image which is limited.
So I know that I have to treat my pictures with Neat Image and something else...
@everybody
I think you understood that you can find Neat Image here :
Neat Image Website
@Paulo
Your process is very simple indeed and I must say that it gives a good result.
I like the way you treated my pictures. On a good display, I can see the differences.
Thank you
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rezz50
Member
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# Posted: 11 Dec 06 17:40
Reply
@paulo
I tried this on some cloudy sky backgroundsthat were grainy after adjusting levels and pushing saturation ; I need to experiment a little more, but I'm getting good reaults. thanks.
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