Active D Lighting confusion

<p>Decided to have a play with Active D Lighting on the D3.<br>

Banged off a couple of identical shots with and without it. Brought them into Aperture and immediately you can see that it's worked, in that the highlight areas are preserved, where they are burnt out on the shot without D Lighting. Good.<br>

Funny thing is though that when I select "Highlight Hot and Cold Areas" in the Aperture menu (this as the name suggests shows burnt out highlight areas and crushed blacks, at least I assume that's what it does!) On the shots with D Lighting it shows area burnt out while on the ones without those same areas don't show as burnt out - even though to the eye it's the reverse!<br>

Any idea why this would be? Seems only to do it when shooting jpegs.<br>

Steve</p>

 

<p>Nikon software engineers do their best in regards to the camera-editing features; the software engineers that created Aperture do the same thing. You can't expect a Ford to run just like a Chevy when you install a Chevy computer into the Ford. I doubt if Nikon Capture NX and Nikon Capture NX2 would act the same for your test...</p>

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<p>Surely though Aperture is just reading pixel luminance levels, it's not editing, just reading what is there. Surely the luminance of the pixel is what it is, there's no interpretation needed. I can't understand why there would be a compatibility problem, unless it's to do with the creation of the jpegs as it doesn't happen in RAW.<br /> The other thing I noticed in quick tests is that the D Lighting shot seems routinely slightly less sharp than the non-D Lighting one.<br /> Steve</p>

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<p>I doubt if Nikon Capture NX and Nikon Capture NX2 would act the same for your test...</p>

 

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<p>Agreed.</p>

<p>Active D-Lighting (Attempts) to prevent blown hi-lites as well as preserve some shadow detail in high contrast scenes. If it's blown; it's blown..even active D won't help.</p>

<p>My understanding is this is accomplished by simply applying a "In-Camera" tone curve.</p>

<p>I rarely use it since I can accomplish this myself with curves if necessary.</p>

<p>Active D IMO is not too great for JPG shooting since the effect is locked in.<br>

Shooting RAW however, and using Capture NX or NX2, the user can turn on or off the effect after the fact.</p>

<p>My best guess is that Aperture can not read Nikon's instruction set as it relates to active D.</p>

<p>Active D-Lighting underexposes the image to preserve highlights, therefore damaging shadow detail and increasing noise overall. It's a great thing if you're shooting for print and need quick results, otherwise it's better to just leave it off and do your own post-processing as needed.</p>

<p>Kevin, Active D-Lighting is not something that Aperture needs to read, it is in the image, even the NEF file. Even the NEF file is underexposed. I stopped using Active D-Lighting. It's a cheap gimmick if you ask me.</p>

<p>D-Lighting as present in Capture NX2 is simply a curve applied to the image, and is useful if you're in a hurry to improve dynamic range in an image. It's useful and I've used it many times on my NEF files. But you can't turn off Active D-Lighting as it has already underexposed your image when the photo was taken.</p>

<p>Thanks. So sounds like might be most useful as an addition to the jpeg route, for those who'd like an image as ready as possible straight from the camera maybe.<br>

Steve</p>

 

<p>I use Active D-Lighting because it works very well with JPEG's and I want to minimize postprocessing. If you shoot RAW then you're better off not using it.</p>

<p>If you shoot raw and use software that is not made by Nikon, you must turn off Active D Lighting. Non-Nikon software does not interpret ADL information, and all you get is an underexposed shot.</p>

<p>Personally I never turn it on. It adds to shadow noise, and the newer Nikon already have excellent DR that gives you quite a lot to work with in Aperture.</p>

<p>Ah - this is the most intriguing thing I have been trying to get my head around... I use D90 with 0 post-processing and shooting in JPEG.</p>

<p>I've seen many posts here that folks say they hate Active D-lighting and keep it turned off..</p>

<p>Can someone please post some links that explain it well - what does it do / what do I lose by using / not... </p>

<p>D-Lighting is not just simply global curve adjustment. <a href="../nikon-camera-forum/00R3bF"> Copy-pasted my answer from an earlier discussion on D-Lighting:</a><br /> Nikon D-Lighting is based on a patented method for dynamic range compression. Nikon licensed the patent from V. Chesnokov (WO 02/089060, <a rel="nofollow" href="http://www.wikipatents.com/gb/2417381.html" target="_blank">http://www.wikipatents.com/gb/2417381.html</a>). The problem of dynamic range compression is to map an output of say, 14 bits (input range), to a much smaller range of say, 8 bits (output range), thereby doing better than simply clipping values which exceed 8 bits. So, if you do it by manipulating curves, you apply the same operation to each pixel (global adjustment). D-Lighting, on the other hand, identifies regions and applies different curves to these regions (local adjustment). Regions may be found by algorithms such as anisotropic diffusion.<br /> Nikon D-Lighting does an area-based dynamic range compression (citing from the patent):<br /> A method of image processing comprising altering an input image using a non-linear image transform to generate an output image, the process comprising correcting an image on an area-by-area basis to generate an output image intensity (1',) of an area which is different to an input image intensity (1,) of the area, the output image intensity (1',) of an area being related to the input image intensity (Ill) of the area by the ratio: amplification coefficient= I'd/ 1, wherein the image processing method produces an output image in which the amplification coefficient of a given area is varied in dependence upon the amplification coefficient of at least one neighbouring area, in order that that, in at least part of the image, the local contrast of the input image is at least partially preserved in the output image.<br /> This is not simply a histogram modification, as this would be a global operation. D-Lighting is more local, that is region-based. However, there are now existing algorithms which give more pleasing results than D-Lighting.<br /> Another thing: Two versions of D-Lighting exist. One that acts on the sensor's dynamic range (14 bit for D300,D700,D3), this should be active D-lighting. Then, a post-sensor version, which acts on a smaller dynamic range.</p>

<p>ADL does fill-light and local contrast enhancement, and also adjusts brightness & contrast. The idea is to make a similar visual impression as we get with our "biovision". The intensity of adjustments is scene-dependent & undisclosed. Essentially (for JPG) the exposure should remain about the same; the instant post-processing (mainly fill-light) causes some increase in exposure, which is compensated by the mentioned underexposure of the raw data. It is a mystery why this underexposure is made by actual noise-amplifying underexposure of raw data, rather than by negative exposure compensation in post-processing (as one usually does when doing similar adjustments manually in a raw converter).<br>

There is an exercise you can do in most raw converters (not Adobe *) to see the odd effect of fill-light on exposure. Open a raw image and drag the EC slider up and down, watching the histogram change (shift left/right). Then add some substantial fill-light (D-lightning, shadows recovery, whatever) and repeat dragging the EC slider; you should see the histogram change in a peculiar way. * Adobe seems to have decoupled this so their fill-light does not alter the highlights.<br>

ADL does not really work on any larger input dynamic range than the default Nikon processing (algorithms in NX converters included). One only gets a visual impression of it due to shadows lifting and local contrast adjustment. The only thing you get from a larger sensor DR with Nikon straigth away is raw headroom. You can use it via pseudo-HDR (multiple conversions at different exposure compensation, then HDR processing) - but it is better to do actual multiple exposures when feasible, noisewise and for better shadows colours. Some other raw converters are able to process more input DR from a well-exposed NEF at once, for example DxO OP and Adobe. Evidence in DPReview camera reviews.<br>

I think ADL is fine with JPG when you like its effect (like all other settings). It is less recommended with raw; the exception is using ADL on auto when you want to take advantage of its highlights-preserving effect on raw data in harsh light and have no time for adjusting exposure compensation manually (at least this tends to be useful on D90 which tends to expose for the midtones in harsh light). But even if you hate wasting time with raw processing like me, the advantage of shooting raw in harsh light is considerable.<br>

There is a lot of room for improvement in the current in-camera algorithms regarding harsh light... more specifically, smarter exposure, exploiting the highlights headroom, and at least a few different presets for dynamic range compression.</p>

<p>If Active D-Lighting is turned on in D300, we know it affects the JPEG result. If shooting RAW+JPEG, does Active D-Lighting affect the RAW file?</p>