How do I get rid of pixelation in blue skys?

If you would like to post, you'll need to register. Note that if you have a BCG store account, you'll need a new, separate account here (we keep the two sites separate for security purposes).

dogdaddy13

dogdaddy13

Active member
Member's gallery
Never noticed it before, or something I am doing different in post, not sure. Lately in my shots of flying Hawks against a blue sky, I am seeing those nasty blue boxes.
I am trying to be careful of enlarging and cropping. But now that I am looking for it, I see it alot more in shots that seem like they should be fine. I have tried Blurr, Gaussian Blurr, and that seems to help. Clearly I am abusing some concept of the craft. Either capture or post. I could use some advise on this one cause it's really TICKING ME OFF.

Bottom 1/3 of this image shows it.

DSC_7106Small.jpg
You can only see EXIF info for this image if you are logged in.
 
I'm not sure.Hopefully you'll get some help here. One thing I'd check would be if the blue channel is blown out there. If using Lightroom there is a way to hover over the problem area and get the RGB values for that spot. If the B at or near the max it might be possible to slide the whites slider a little left, or get into the curve and click in the image and pull it back a little. If it's all the way blown it will not help, all you can do is clone some sky from another area,
 
Member's gallery
aolander said:
I think the issue is banding. Heavy of processing of an 8 bit image? Is original a RAW?
Click to expand...
Yes I shoot everything in RAW. I then use Nikon ViewNX to review my shots and convert to Tiff, and open and work on my image in an old version of Photoshop.
I think I am using Photoshop 6. Anything going to the web gets knocked way down in size and saved a jpeg.
 
Member's gallery
As Alan said, I think banding and processing are the areas to look at. This does not look like regular noise. Do you see this on the TIFF file you are working on, or only on the jpeg that you export for use on the web. Maybe the file is simply too compressed when you convert it to jpeg?
 
Member's gallery
My first thought was that you were using ACR to convert from RAW as that has been when I would see banding problems. Suggest sending the file in to Nikon to evaluate as the problem is likely with their ViewNX software.
 
Member's gallery
Thank you all. Do not see the problem in the Tiffs. I am using 8bit. When I try to use the 16bit some of my tools no longer are available. I think that I am pushing the images too much to get a closer looking feel. I crop a good half of my image. I am shooting a small subject at a long distance. Some times I am 1.3x crop on top of the 1.5x in my DX. I am preplanning on loosing a lot of the image. From 24mg file I am looking at 12mg sometimes. I can get a really nice 11x14 print from that. At least this has been my direction. Could it be the post process is kinda of at the limit with my Tiff, and the compresion of the jpeg shows all my sins. Clean sensors and lens religiously.
 
Member's gallery
aolander said:
Do all the editing you can using 16 bit and convert to 8 bit only if you need a tool that needs it and do that last.
Click to expand...
Ok, that I can do. When I am all done I am guessing save the tiff at 16 bit? Make my jpg from the 16bit tiff. Can I go back and edit later, switch to 8 bit and then go back to 16 bit again? Also, is this kind of the standard way everyone is editing their images?
 
Member's gallery
I do most of my editing in Lightroom and don't save as anything unless I need a jpeg or tiff for something (like a jpeg to email). (Lightroom saves all the edits without changing the original RAW file. You can edit and re-edit at will.) If I need to go to Photoshop for something, I go from LR to PS and save a tiff back to LR. Yes, save your tiffs as 16 bit, but jpegs can only be 8 bit. You lose data going from 16 to 8 bit and you can't recover that going back the other way. Just save your tiffs, and if you need a jpeg, you can make one.
 
Member's gallery
aolander said:
I do most of my editing in Lightroom and don't save as anything unless I need a jpeg or tiff for something (like a jpeg to email). (Lightroom saves all the edits without changing the original RAW file. You can edit and re-edit at will.) If I need to go to Photoshop for something, I go from LR to PS and save a tiff back to LR. Yes, save your tiffs as 16 bit, but jpegs can only be 8 bit. You lose data going from 16 to 8 bit and you can't recover that going back the other way. Just save your tiffs, and if you need a jpeg, you can make one.
Click to expand...
Thank you for your reply. I think I have enough information now I can start looking at my procces and make changes. :)
 
Member's gallery
Charles,
I have gotten rid of this in a couple photos running the photo through TopazDeNoise. I mask only the pixelated area so as to not "de noise" the entire photo, turn the remove noise slider most of the way up and sharpness all the way down.

For a more or less featureless sky it works to smooth the edges. You could also use a softening brush in your post processing software.

What causes it I don't know but it does sometimes show up in photos where the sky is featureless but has a gradual color or intensity shift across the image. Seems mostly to shot up on the "line" where colors or brightness shift.

Hope this helps. I'm sure there are more elegant solutions than mine.
 
Member's gallery
Those little squares are JPEG compression artifacts. While the explanation is pretty complicated, your entry points to dealing with them are quite straightforward. If you have not set your program's JPEG file export to highest quality, do so. If your program allows you to select the JPEG format, choose 4:4:4. If those things don't work, consider not saving the files in JPEG. FWIW
 
Member's gallery
dogdaddy13 said:
Can I go back and edit later, switch to 8 bit and then go back to 16 bit again?
Click to expand...
You can, but you do not want to because not only will it not help you, but it can actually cause further degradation. If you start out 8-bit, a jpeg for example, then stay there. If you have a higher bit file, then work with 16-bit friendly tools for as long as possible. And if you start out with a jpeg file, remember that every save will cause a new generation of file that will add to compression artifacts. You may not see it on one save, but it will eventually add up.

--Ken
 
Member's gallery
dogdaddy13 said:
Never noticed it before, or something I am doing different in post, not sure. Lately in my shots of flying Hawks against a blue sky, I am seeing those nasty blue boxes.
I am trying to be careful of enlarging and cropping. But now that I am looking for it, I see it alot more in shots that seem like they should be fine. I have tried Blurr, Gaussian Blurr, and that seems to help. Clearly I am abusing some concept of the craft. Either capture or post. I could use some advise on this one cause it's really TICKING ME OFF.

Bottom 1/3 of this image shows it.

View attachment 31932
Click to expand...


Pixelation is the result of over processing or not enough information in the file, which actually means, in many cases, that the original file did not have enough information to be pushed and pulled around. Blue sky is particularly susceptible to pixelating, pixelation is called an artifact and is generally considered to be a negative, the same with banding. I have, however, seen someone who actually loved the banding caused by a low resolution file so I guess each to their own. One reason for low color information in the sky can be that the shooter used a higher key exposure and the blue in the sky is susceptible to blowing out easily anyway, so once processed the lack of information shows up as pixelation. To avoid this issue I shoot in RAW and process in RAW, only downgrading the image when I want to export it, usually as a JPEG. I am careful with the JPEG settings so that the file stays intact without the loss of resolution being evident. I work from within LrC on images, going back and forth between various software programs in TiFF or Photoshop format and always in 16 bit.
 
You must log in or register to reply here.
Back
Top