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Help: Severe Posterization of Sky with 5D RAW

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I have seen this effect with my polarizer as well.. I belive it may be some underexposure as well. Especially when you tack on some vignetting.

Johnny
 
problem_child said:
I started using Lee ND grads and lin. polarizer. Until that time my
skies were fine. Now I have the same issue. Talked to Lee today and
they say its underexposure possibly. Im sending him the raw files
to look at.
Click to expand...
I thought modern cameras needed circular polarizers for the AF to work. Do you use MF?

--
Greg
http://www.pictureroanoke.com

Photography is a journey, not a destination.
 
You've probably clipped your blue channel. The camera is not the problem, none can handle that.
 
Michael Friedman said:
I was dismayed to find
that in most of the RAW shots containing the sky, the blue was
severely posterized, or had large, blocky areas of color. The jpg
versions showed much less of this effect.
Click to expand...
If the JPEGs are OK, the original capture is not the problem, it's your processing of the RAW files. Using 8-bit rather an 16-bit processing, combined with large levels corrections, is the most common cause of posterization.
Andy
 
Yep I've experienced this, particularly when using a grad and a polarising filter. I think there are a number of factors involved, but the main one is a slight under exposure to the sky.

All is not lost, I've found that by making a hue / saturation adjustment layer and subtly tweeking the the blue channels hue and saturation you can get it to disappear. Be gentle or you'll end up with some weird clour casts.
 
Hi,

I know you think it isn't the monitor, but I want to throw this into the pot.

When I had this problem it was the colour temperature setting of the monitor. No amount of calibration fixed it, but adjusting the monitor itself eliminated the banding.

Rob

--
‘Lose civil liberties or suffer terrorism’ is a dilemma.
‘Which lens should I buy?’ is a choice.
 
I am using 16-bit processing (well, 12 bit, actually). I also checked the histogram on these images, and the blue channel does not appear to be clipped, either. I am now feeling pretty certain that what I am seeing is due to underexposure, due to not compensating enough for my ND filter or polerizer.

I've also noticed that once I convert the RAW file to TIF, the effect is considerably less noticable, though it is still there. In TIF format, it looks more like noise than posterization, or large blocky areas of color ... but it is still not acceptible. It takes a couple of passes through Noise Ninja to get rid of the remaining artifacts, and it softens my photographs more than I'd like to see. I can get get rid of most of the unwanted softening using layer masks, but it's a lot of work. Still, the problem is less bad than I thought in my initial reaction.

I'm still working on finding meaningful samples to post.

-Michael
andycgw said:
andycgw said:
I was dismayed to find
that in most of the RAW shots containing the sky, the blue was
severely posterized, or had large, blocky areas of color. The jpg
versions showed much less of this effect.
Click to expand...
If the JPEGs are OK, the original capture is not the problem, it's
your processing of the RAW files. Using 8-bit rather an 16-bit
processing, combined with large levels corrections, is the most
common cause of posterization.
Andy
Click to expand...
--
-Michael
http://www.novalight-imaging.com

'When you come to a fork in the road, take it!'
-Yogi Berra

 
Michael Friedman said:
I am using 16-bit processing (well, 12 bit, actually).
Click to expand...
I don't quite understand what you're saying here; the RAW files are 12-bit, and can be converted to either 8 or 16 bit TIFFS for working in Photoshop. If you're seeing smaller posterization affects after conversion to TIFF, then most of the original problem was presumably over what your RAW converter was displaying, which is always a relatively rough preview.

I'd agree that any remaining issues are likely due to underexposure - an already deep blue sky, with full polarisation, will get very dark blue. Add in an ND grad, and your sky will become severely underexposed. One of the most important things to learn with a polariser is that often the strongest effect is extremely unsubtle; it's important not to over-polarise.
Andy
 
My issue is with a jpg, not RAW, and its definitely a PP Issue for me.

I checked the original jpeg, and its fine, but after PP, saving it (Adding more compression), then uploading it to pbase (adding more compression), I think this is the look of posterization we are talking about. Other may have come by it in other ways, but it seems, this is how Ive gotten it.

The image on my hard drive is not really that bad, but whats on pbase has become pretty severe.



Sorry for the large image.

Johnny
 
Yiannis said:
My issue is with a jpg, not RAW, and its definitely a PP Issue for me.

I checked the original jpeg, and its fine, but after PP, saving it
(Adding more compression), then uploading it to pbase (adding more
compression), I think this is the look of posterization we are
talking about. Other may have come by it in other ways, but it
seems, this is how Ive gotten it.
Click to expand...
This is jpeg posterization due to too high a compression. It's just the nature of the compression algorithm and not an effect of lens, camera, etc. These things are most noticable on gradual gradients. Not much you can do but use less compression. Also, every time you read in a jpeg and write it out your image will deteriorate a bit.
marty
Yiannis said:
The image on my hard drive is not really that bad, but whats on
pbase has become pretty severe.



Sorry for the large image.

Johnny
Click to expand...
 
Ok, I had problems with this (on a 300D) years ago and I found it was clearly to do with the processing itself. The raw data behind the scenes was fine, and my monitor was fine (and spyder calibrated).

Basically when I use DPP to convert my skys and nighttime sky, the shots are perfect. If I use C1 Pro (which I prefer to be honest) or Adobe Raw convertor I sometimes get the posterization you describe. It is bad too. And the level of sharpening and all the other settings in each program were set either "off" or as stardard as possible to keep things uniform when I was doing my testing to figure out what is the program. I noticed that when I tried my "test" photo on the most recent DPP (2.2) it was fine, and the latest Adobe CS2 raw convertor gave me posterization.
I left everything at 8 bit (to force any problems out).

Please do one test before you spend too much more time. I know that DPP isn't an overly popular program (and I'm not necessarily going to recomend it to you over other programs), but for the purposes of a test please download it, and convert the photo and tell us if it the problem still exists.
DPP can be found here (after following a few links):
http://www.usa.canon.com/consumer/controller?act=DownloadIndexAct

I use DPP now, to avoid the posterization problem, but I have also resorted to doing a C1Pro conversion to get the rainforest etc, and then a DPP conversion to get the sky, and then blended the two.
Let me know if DPP does or doesn't give the problem!
Cheers,
Tony
 
anthony rayner said:
As a follow up to this posting...have a look at:
http://forums.dpreview.com/forums/read.asp?forum=1032&message=21329117

Cheers,
Tony
Click to expand...
With ref to the linked thread and reading back up this one, it seems that Steven was right on the money with suggesting NR to be turned off.

Pity I didn't see it sooner..... but then I may not have found that Lightroom with NR off and in 16bit, produces way better results than the other converters I tested. ;-)

Cheers

Rusty
http://www.pixelpix.com.au/gallery
 
Michael Friedman said:
Has anyone had this experience:

I just got back from a week in the Aspen area, where there'd just
been 15 inches of snow. I did a lot of shooting using my 5D and a
variety of lenses. Many of the shots of were of snow-covered
mountains under a deep blue sky. I shot exclusively RAW+Medium JPG.
Click to expand...
Sorry this happened to you, I have seen it here and there as well. I rarely shoot with filters though, so it is 1/10,000 that it happens. I hope you did get some pics that you did enjoy, I live in Aspen and have photographed life here professionally for nearly 9 years, I never run out of ideas or images..:-).

It is snowing pretty good now, I had better get to bed....
 
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