ron_togger

<p>OK, I think we're getting somewhere.<br> I just tried opening the NEF directly from photoshop. It seems that after heavy posterisation, a very tiny difference occurs between the original 14-to-16-bit and the up sampled 8-to-16 bit. Too tiny a difference to say "wow, this is clearly superior", but a difference nonetheless - confirmed in the histogram.<br> View NX continues to produce identical results. This would suggest my earlier notion that View NX cuts the data before exporting it...</p>

<p>..erm btw thanks for your comments Tim, actually I am interested in beautiful images. Which is why I want to ensure I understand my equipment and software as thoroughly as possible. I am not using an 8-bit video display, and I'm not out to boast about my equipment.<br /> What I will say is that since I do not have the luxury of owning a darkroom or a large format film camera any more, I am trying my best to yield the best result in B&W photography using digital as I possibly can. These may well be "minute piece of technology" but actually, I do give a sh*t about it - if that's OK with you.</p>

<p>Greg, Andrew thanks for your comments - that is exactly my point. Both files are up-sampled to the same 16-bit photoshop space. If I paint a gradient at this point and start playing with it, the *painted gradient part* of the image is obviously smoother than the same process repeated within an 8-bit space. I can see the superior 16-bit result in line with my expectations and the difference is obvious.</p> <p>BUT... what I don't get is the actual captured photo itself.</p> <p>Forgetting filters for a moment, if I take an 8-bit photo and convert to 16-bit, next take a 14-bit photo and convert to 16-bit (which is effectively what I did in the steps above), would it be reasonable to expect the photo itself to hold more data/subtle tones "hidden" within the image? If I then applied the same extreme posterization side by side, to the point where both images are pushed to reveal banding and grain, should the converted 14-bit version not be at least slightly better than the one originating from an up-sampled 8-bit? In other words, if the camera originally "sees" and records 14 bits worth of tonal variation, should the resulting high-bit TIFF not be visibly superior to an up-sampled 8-bit, following all the editing?</p> <p>I cannot see any difference: it is as though both sets of outputs (the 8 and the 16 bit TIFF) contain identical amount of actual image data. The "16-bit" TIFF which I am outputting from Nikon simply appears to have 6 bits chopped off, then 8 bits of extemporaneous data appended to it. Hence, when both are edited side by side in 16-bit space, there is zero difference. This would seem to indicate that somehow the RAW data is internally clipped to 8-bits before it even "leaves" the Nikon domain, regardless of which TIFF bit rate you ultimately choose.</p> <p>As I said originally, maybe I'm missing something here. It's not gonna ruin my sleep but if I'm right, then folks have been exporting 8-bit images to photoshop all along, mistakenly assuming they are "high-bit" when in fact, the only "high-bit" elements are Photoshop-generated artefacts like gradients and effect filters - NOT the actual images you start off with.</p> <p>Please prove me wrong...</p>

<p>...so if anyone wants to have a little investigative fun, try the following.</p> <p>1) Open up a NEF file in Nikon View NX. Preferably with light pastel shades across wide areas.<br> 2) Export the file as 8-bit TIFF from View NX.<br> 3) Then export the file as a 16-bit TIFF from View NX.<br> 4) Open the 16 bit TIFF in photoshop.<br> 5) Open the 8 bit TIFF in photoshop.<br> 6) Apply your choice of posterisation filters (comment 5, as per Andrew's suggestion) identically to both files. At this stage, there are obvious visible differences. So far so good. 16-bit looks better than 8-bit.<br> 7) Close files without saving.<br> 8) Open both again, the 8-bit and the 16-bit<br> 9) Now, interpolate the 8-bit upward, by cutting and pasting it into a 16-bit window of the same dimensions so you end up with two identically sized 16-bit versions of the same image, one being the original 16 bit, the other an interpolated 8-bit<br> 10) Apply the same choice of posterizing filters.</p> <p>Is there any difference between the two? Remember, one is meant to be the 14bit interpolated to 16 bit, the other only an 8-bit interpolated into 16 bit.</p>

<p>Many thanks for the responses guys. Tim & Andrew, apologies if I've overcomplicated the question. What I'm trying to get at, is whether a supposed 14-bit raw file I'm opening up in Photoshop is, in fact 14-bit upped to 16, as I see no difference in results between the "upwardly interpolated 14-bit" and "upwardly interpolated 8-bit" files. (Hence my experiment: opening the original straight off as 16 bit, and opening an 8-bit version of the original, then interpolating it to 16bit). It's almost as if the original 14-bit data only really exists in the Nikon proprietary domain, (ie. View NX), but gets chopped as soon as you export it, regardless of whether you're saving it out to 8-bit, or a 16-Bit TIFF. How else would the filters behave identically on both?</p>

<p>sorry... I forgot to add that I deliberately chose images with very light colours and applied extremely heavy level editing to deliberately darken light shades in order to force the banding and other visible artefacts. Some edits DID indeed, produce visibly reduced banding on the 16 bit. I thought I'd solved the puzzle....however...<br> ...I then tried one final test: Create an empty 16 bit document, copy and paste the unedited 8 bit image directly into it, keeping the original 16-bit image open as well. I then applied exactly the same processes to both files. Guess what. Both the "original 16-bit" and the up-sampled 8-to-16 bit files behaved exactly the same when processed using heavy filtration. Unlike the first attempt which eventually produced some subtle differences, this did not. I'm completely lost on this one.</p>

<p>Thanks for the response. It's a puzzle to me. The D3 capture was in Adobe RGB 14/bit uncompressed. Perhaps I am trying the wrong level filters to test these or the differences are too subtle for my iMac monitor...</p>

<p>I cannot get my head around this.<br> Having exported the same 14 bit NEF Nikon image, firstly as 8bit TIFF, then a 16 bit TIFF (both uncompressed), I applied identical extreme level adjustments to both images. Surprisingly, I cannot see ANY difference in final image quality between the two. Both 8 & 16 bit images look the same, with the same artefacts like gradient banding.<br> Logic dictates that raw 14-bit files saved out to 16bit should retain more fine tones compared with a "clipped" 8-bit. Applying photoshop tools like airbrush and grad fills makes an obvious difference - the 16 bit file is much finer, but this only applies to photoshop-rendered objects and not the original photo. It almost seems like the 14bit RAW is in fact only 8 bit.<br> Am I missing a major trick here?</p> <p>Equipment used:<br> Nikon D5100 in RAW mode / View NX2 to convert / Photoshop CS5 to edit. Also used a D3 in RAW mode. Same results.</p> <p>Any comments welcome.</p>