Digital Banding

<p>Ran into an interesting phenomena on a project I am doing for work. Over three weeks I've shot about 4000 images using a D4 and a D700, and a number of different lenses. On two images (unfortunately ones work wants to use) I've noticed a type of banding in the broad, flat, even toned section of the shot. Reproduced below:<br>

<img src="http://www.timcarrollphotography.com/Forums/Band-1.jpg" alt="" /></p>

<p><img src="http://www.timcarrollphotography.com/Forums/Band-2.jpg" alt="" /></p>

<p>Both images were shot in RAW, ISO 400 and ISO 2000, one from each camera and with different lenses. I'm not sure what is causing this and was wondering if anyone knows.</p>

<p>They aren't jpg artifacts because the banding is there on the RAW files, whether I look at them in Apple's Aperture 3 or DNG convert them and view them in Photoshop.</p>

<p>The grey image was of football stadium bleaches, way out of focus, and the orangish image was of a brick wall, also way out of focus. Was wondering if the camera sensor might have been picking up the pattern in the bleachers or bricks and that caused the banding. Not sure what caused it and I'd really like to know so I can avoid it in the future. Since it's in the RAW file, there no easy way to get rid of it, short of cloning it out.</p>

<p>Best,<br>

-Tim</p>

<p>I would guess it is just the subject texture or what is left in the out of focus image projected by the lens. I don't think it is sensor related. One way to check is to see if the lines actually coincide with pixel rows, or not. If they aren't exactly aligned with pixel rows/columns then it's unlikely it's sensor related.</p>

<p>Thanks for your input Ilkka. The banding is so faint when you try to look at it at pixel level that it's hard to tell.</p>

<p>In the second shot, more clearly, as Ilkka points to, the lines look not to be totally horizontal. So not a sensor issue but a subject issue.<br>

Actually it seems that in the first image the "banding" seems to converge to the right. This would indicate that the right part of the background was further away. True?<br>

To cure this you should change your shooting location :-)</p>

<p>:-)</p>

<p>Yes, the right part of the background was further away.</p>

<p>Something to think about in the future.</p>

<p>Looks like digital noise to me, you get the same sort of banding if you HDuf the heck out of an image. More usual at ISO2000, though, but some cameras can do this at ISO400, especially if the "post" is hot and heavy.</p><div></div>

<p>I do not think this is banding at all. If you're concerned, you should do tests on a subject that does not have horizontal lines (like bleachers and brick walls). The D4 is typically very clean at low ISO settings, close to the D3x, due to some enhancements. It doesn't have the "Canon problem". I've only seen the very barest trace of banding from the D4 at ISO 25600 + in normal use, and even then, not enough to spoil the picture. It's not even a typical "failure mode" that I've seen.</p>

<p>Hard to say without seeying the rest of the picture.<br>

Are there by any chance any filters attached to the lens(es) ?</p>

<p>Clear NC on both lenses. No banding anywhere else on either picture.</p>

<p>Best,<br>

-Tim</p>

<p> Ok, then i'll have to agree with JDM, and this an example of "Banding Noise"which is created often by in camera amplification of the sensors readout signals. The readout patterns of the sensor can become more obvious in the resulting pictures in areas that are largely the same set of colour tones because of this amplification in certain circumstances.</p>

<p>If you want to process shots showing banding noise it sometimes helps to add a litle artificial noise on top of the existing noise in the affected areas by means of a self created noise layer than try to eliminate it, this way it is smoothened out more and becomes less Obvious.</p>

<p>For this kind of processing i like Damien Symonds website since this guy knows how to explain how to do this a lot better than i can, so i went to his website to see if he has a recipe for this and found the following which might help to improve your images :<br>

http://www.damiensymonds.com.au/tut_noise.html</p>

<p> </p>

<p>Have you had the sensors wet-cleaned by any chance Tim?<br>

The banding doesn't look horizontal enough, or sharply defined enough to be noise of any sort. My first guess would be that this is streaking on the sensor caused by a wet clean wiping motion.</p>

<p>Ahhh! I've just realised that "bleachers" are horizontal stands of benches right? Sorry, but here in the UK we don't use such an obscure term. We just call 'em "stands". Surely the "banding" could just be the out-of-focus lines of benches? Likewise defocussed courses of bricks could be the cause of the brown horizontal lines in the second shot, since the central grey section of the cropped image shows no sign of banding.<br>

And yet you make no comment on the dark diagonal blobs in the first image, which are very obviously simply real and OOF objects in front of the camera.</p>