D700 color bands in sky.. revisited

<p>I've had this problem with my camera since day 1. Nikon have had the camera in for a service, check up and up date and says that all is well. I would be interested to hear if the problem is universal. I would also be grateful for photoshop correction advice, in easy stages if possible. I have had help on this subject a year or so ago but thought a revisit would help.<br>

In very clear weather the camera records obvious banding in the sky. I don't know if its because of clipping in the blues or an inability for the sensor to cope with extreme levels of blue. It records the same on jpegs and raws, so has little to do with compression, and shows on prints big time. Day time or evening shoots don't make much difference only the clarity and saturation levels of blue seem to be the main influence. </p>

<p>Ian,<br>

Could you possibly post an example mentioning settings, lens, and eventually filter(s) used ?</p>

<p>http://www.photo.net/photo/11893191<br>

camera set on... A priority...24-70 lens though it makes little difference..uv filter again it seems to make little difference.<br>

f22 at 1/15 iso200 though again I can get this result with other settings etc<br>

I hope you can find the photo from the link</p>

 

<p>Color banding? Or those lines across that I can faintly see on my monitor?</p>

<p>I cannot check it right on my monitor (it is a very bad office one), but I`d say it`s posterization. Higher color bit depth will help to avoid it. The color space used could also be the culprit of this issue, thought.<br /> Also, a low dynamic range pic could show this issue after processing. Maybe you should check the way/conditions you take your pics, and your processing way.<br>

I bet it`s not a D700 fault.</p>

<p><em>"I bet it`s not a D700 fault."</em><br /> Too late for editing, I should have checked it before writing. I have already remember a straight pic of mine with an extreme posterization efect... but I don`t recall if it was taken with a D300 or D200.</p>

<p>If you are shooting in just jpg, could it be the quality is set to low and the jpg compression set to max?<br>

looks like it's trying to minimize the number of colors and thus save space. </p>

 

<p><strong><em>Camera is set to highest possible quality jpegs and I also take raws at the same time</em></strong></p>

<p>Does look to be posterising on the image.</p>

<p>Interestingly, the initial pic shows horizontal bands, but when you view at 100%, they disappear completely, but slight arc banding is visible (far less noticeable than the horizontal banding though - so not sure this is the problem you are referring too).</p>

<p>It could be more to do with the display settings on the monitor as much as in camera processing.</p>

<p>Do you have full exif data for the shot ? were any other processing options set in camera ? (ie vivid colour etc).</p>

<p>Martin</p>

<p>Ian, does it show in prints as well?</p>

<p>Ian: Interesting. If you say you've seen in in RAW as well, it's probably not just the JPEG engine. Are you capturing in sRGB or AdobeRGB? When RAW processing, what colour space and bit depth are you using? If you're hitting the bounds of sRGB, you might have to reduce the saturation a little in the final image for final display - it might be worth trying this in RAW and seeing whether you still get banding. Or you could be right and you're hitting the sensor (or image processor) limits.<br />

<br />

If it makes you feel better, I have a Windows Mobile phone whose camera app crashes whenever there's too much blue in the image (AFAICT). Fortunately I live in the UK, and it's not an issue too often...</p>

<p>If you could post the original raw file somewhere for people to download, that would make it an awful lot easier to diagnose.</p>

<blockquote>

<p><em>Its the arc banding that is giving me trouble. Camera is set to default more or less and set on neutral, rgb makes no difference. There is in my opinion nothing I can do in camera that will cure this, furthermore it is definitely originating in camera and shows on prints big time. Editing a 16bit raw does not cure it either. It needs some very clever editing skills to sweep it away and leave nothing but clean graduated blue skies</em></p>

</blockquote>

 

<p>As a follow on from my earlier post I have had to start a new one because for some reason I couldn't get it to accept my reply.<br /> So as a sum up I can say with 99% certainty that the bands of noise arcing across the sky originate in camera regardless of the setting rgb, raw or otherwise. It only occurs when and I'm guessing here, the atmospheric conditions give rise to high amounts of blue. I'm surprised no one else has experienced it as I have witnessed this phenomena on TV programmes showing sunsets where there is a strong gradation from the yellows to the blues of the upper atmosphere.<br /> What I don't know is if my Nikon camera is unique in failing in these conditions and how I cure it quickly and easily in photoshop.<br /> see link to photo<br /> http://www.photo.net/photo/11893191</p>

<p>This may be a dumb comment, but are we 100% sure it's not an optical illusion of some sort ?<br>

On my monitor I cannot see the banding at all, and the arcing lines I can maybe see but not sure.<br>

Banding of colours I HAVE seen before, but on my TV, when I suspect the colour range is insufficient to graduate the colours accurately.</p>

 

<p>Are you using D-lighting? If so, that could be the problem. I've noticed that using D-lighting causes very noticable posterisation in the camera's review histogram, so I refuse to use it. I shoot RAW all the time anyway, so I don't really care what happens to the JPEG version, and the tone curve can always be altered in ACR or PS at 16 bit depth.</p>

<p>Try turning any D-lighting settings completely OFF and shoot RAW. I'd be very surprised if the RAW files showed any sign of posterisation.</p>

<p>Another thing to try is just running the colour-picker over the apparent banding in PS. If it's real, then the colour picker will show up the step. Some LCD monitors only work at 6 bit quantisation, and so cannot show smooth gradations properly. I was heartbroken when my faithful old glass CRT monitor finally packed up and I was forced to buy a crappy LCD display.</p>

<p><em>"I'm surprised no one else has experienced it... "</em><br /> I`m not an expert, but to the best of my knowledge it is normal on digital cameras. The deeper bit depth the lesser "step" effect. It not only happens to clear blue skies, but to e.g. flat dark studio backgrounds.<br /> I`ve been checking some of my D700s "beach" pics (the very few I have on this computer), and I hardly can detect it... although I don`t use to shoot landscapes or uniform flat areas. I use to avoid too much sky.</p>

<p><em>"I don't know is if my Nikon camera is unique in failing in these conditions... "</em><br /> I bet it doesn`t. I don`t think so.</p>

<p><em>"... how I cure it quickly and easily in photoshop."</em><br /> Just add noise. I tend to think that it should not happen at high ISO settings.</p>

<p>http://www.photo.net/photo/11894832<br>

camera is set to Auto D lighting, and standard or sometimes neutral <br>

Banding arc is much less visible on a raw taken through photoshop <br>

and converted to a jpeg see link BUT if you look closely there is still banding<br>

and rest assured it will show on a print</p>

<p> </p>

<p>Oops - I've just looked at the full size image (there was separate posterisation in the small version).<br />

<br />

I think you're running into the limits of 16777216 colours: you have a slowly-changing gradient across a relatively small number of colours. 256 shades of each channel isn't as many as you'd think: the eye is very good at noticing a small discontinuity if there's a large area of one colour with another very similar colour next to it. If you shoot in RAW, use ACR outputting to a 16-bit (per channel, 48 total) intermediate, then convert to 8-bit (per channel, 24 total) with dithering enabled in colour settings, Photoshop should add some dithering to approximate the full (12- or 14-bit) range of the sensor data. That ought to help for printing, unless the printer tries to add some sharpening and accentuate the boundary (and if you can't print directly from 16 bits). When you convert it to a JPEG, you'll probably get the banding again, because JPEG isn't designed to handle high frequency changes with small colour differences - dithering works because the eye can't see it very well, and JPEG compresses by throwing away things the eye can't see. Short of saving a dithered PNG, which will be *big*, I don't have a good solution. Except possibly JPEG2000 and saving the 16-bit image, at least.<br />

<br />

As for fixing a JPEG once it's in this state... it ought to be possible to do something to detect an approximation to a gradient in 24-bit colour space, smooth it in 16-bit per channel, then do something with the result. It may be simpler than that - you could just convert to 16-bit, select the sky, apply an enormous blur filter to it and go from there.<br />

<br />

To quote Knuth (a famous computer scientist), I've only proven this correct - I've not tried it. But I hope that helps - it's at least worth a try.</p>

<p>There is *LOTS* of information about this problem already on the web, including many threads on photo.net. Please read this one: <a href="../digital-darkroom-forum/00Vl7k">http://www.photo.net/digital-darkroom-forum/00Vl7k</a></p>

<p>Cheers,</p>

<p>Tom M</p>

<p>The only way to find out if the posterisation is present in the raw files is to analyse the data.<br>

The second best approach to the original data and easiest is to convert NEF to 16bit tif files and then to analyse the data by looking at the numbers. Or using some quantitative software like "imageJ" (free software) that will allow to show line profiles of the data along a selected line in the image.<br>

Until proven otherwise I bet that the banding is some posterisation either during post processing or when inspecting the images on a monitor . A "typical" monitor can only display 8bit resolution per color channel. One can easiliy run out of color resolution. And you are not the only one to see this - you are in a large number of people :-)<br>

So even if your files are perfect using a monitor may downsample your perfect sky into visible steps of blue.<br>

The above suggestion to look at prints is a valid one - if the effect is not visible on prints it is the monitor or post processing for monitor viewing. But if the effect is visible on prints we still do not know and one has to quantitatively analyze the images.</p>

 

<p>Let's address it as either a possible capture compression, raw processing, color space, output setting, or possibly a display issue.<br>

When you shoot your NEFs do you have the camera set to compressed, uncompressed or lossless compressed mode?<br>

Are you shooting 12 bit or 14 bit per channel NEFs?<br>

When you have imported the photos into your raw processing program (which one?) what are you doing to the data, what processing steps? When you are are ready to output as JPEGs or TIFFs, what color space (sRGB, Adobe RGB(1998) or ProPhoto RGB) and bit depth are you using to create the rasterized file in? <br>

Finally you may be seeing something on your display that I can barely see. Which display are you using, how is it calibrated and profiled, and what are the settings you are calibrating to? </p>

<p>I hope this answers.....<br>

lossless compressed mode<br>

14 bit<br>

ACR <br>

Adobe RGB 16BIT<br>

Saved as a tiff 16 bit<br>

display....I have seen the image on 4 displays including iMacs all show it the same <br>

and on a A3 print<br>

thanks for all the help on this</p>

<p>Try ProPhoto RGB instead of Adobe RGB(1998), ProPhoto has a much larger blue gamut. </p>

<p>I use a D700, have for a couple of years. I've never had this problem in clear blue skies, of which I have many photographs. You have my sympathy, which isn't going to help a bit... t</p>

<p>Ellis, the size of the blue gamut is not the issue. In fact, with a larger gamut, the visual difference between adjacent levels (especially at 8 bpc) becomes noticeably larger, making posterization worse, not better. Historically, this was exactly the reason cited by some early opponents of ProPhoto. Of course, at 16 bpc, this is almost a non-issue unless one is really stretching out some small differences in the sky to make it appear more visually interesting. </p>

<p>Tom M</p>