EXPEED processing vs. RAW for noise reduction

<p>I'm a new D700 owner and I'm curious about the D700's low ambient light abilities.</p>

<p>It's obvious that the D700 is a great machine, but where does it do it's noise-reduction processing for each workflow (jpeg and RAW)? I'm logically assuming that a jpeg has the "advantage" of the EXPEED's full processing for noise reduction (as well as chromatic aberration reduction). Does the RAW file get any of this EXPEED noise reduction? </p>

<p>In other words, is a low-light shooter better off shooting in jpeg, or RAW for cleaner pictures? Please use the assumption that I won't be using any noise-reduction software during RAW processing.</p>

<p>Thanks for all your opinions.</p>

<p>David.</p><div></div>

<p>If you use the Nikon software NX2, and open a RAW file, you in effect have access to all of the processing done by EXPEED, with the advantage that you can tweak it post capture. And in addition you always get better results shooting in RAW, then converting to JPEG post capture, in part because RAW has 16 bits of information (though only 12 or 14 bits are used) versus 8 bits, and in part because the in-camera JPEG is a compromise due to the need for speed.</p>

<p>David, I can't assist you with your question, but I love your photograph and I'm absolutely stunned by what the D700 is capable of. Great job all around!</p>

<p>If I'm understanding the process correctly, in camera NR uses dark frame subtraction to generate noise reduction. Using noise reduction in post processing would rely on a different technique. I've tried both with my old-tech D2H (which offers only long exposure NR) and get very different results. Neither is clearly superior to the other and it depends on circumstances. Newer Nikon dSLRs use different technology so my results may not apply.</p>

<p>If you prefer to shoot JPEG for whatever reason (I do for most casual event photography where I just burn a CD and give it away), use all the in-camera features you can. I don't do any post processing for the freebies I shoot so I'd definitely take advantage of every in-camera processing feature. I wouldn't recommend my sloppy technique to anyone else.</p>

<p>Why not run a few tests and compare for yourself? With and without in-camera NR, and also test trial versions of Noise Ninja, Noiseware and a few others? Human skin is great for noise reduction tests because chroma noise is readily visible in most skin tones. You can compare relative sharpness by examining the effects of luminance noise reduction on fine details such as eyelashes. I'd be interested in seeing the results of such a comparison since few of the online tests of noise reduction I've seen use portraits for comparisons.</p>

<p>Thanks for all the answers. Leif, good info, but I don't use NX so that's a non-player. I use Aperture.</p>

<p>Jeffrey, thanks. I'm stunned also. I'm a die-hard film fan, but I never got the results out of film I'm getting with the D700, especially using RAW.</p>

<p>Lex, you caught me being lazy. I guess I'll try some tests on my own. I was hoping I could cheat and use somebody else's experience! So I think I'll just shoot a couple of casual portraits at 3200 and 6400 both ways and pixel-peep (which I hate admitting) just to satisfy my curiosity. I'll report back.</p><div></div>

<p>David, my understanding is that the term EXPEED is Nikon's term for all of the electronics between the sensor and the buffer. If you choose the in camera noise reduction settings these will be applied to both exported RAW and JPEG files. For most applications, setting the in camera noise reduction settings to off or normal seems to yield the best results. For the most flexibility in post-processing you should shoot 14-bit RAW uncompressed and deal with noise and everything else in your post-processing work, unless, as Lex says, you want to do some quick JPEGs and let the camera do the processing.<br>

Dick</p>

<p>David,<br>

With RAW your computer's Intel Core 2, Core quad or Core i7 becomes the "Expeed" processor with far more firepower than the small chip in the camera. You can apply much more sophisticated noise reduction or CA correction on your PC once you shoot in RAW. Nikon Expeed or Canon Digic chips are DSP ASICs fabricated by Texas Instruments and then rebranded by Nikon/Canon, the branding Expeed, Digic, Magic etc. is mostly for marketing and offers little benefit to RAW shooters.</p>

<p> </p>

<p><em>"If I'm understanding the process correctly, in camera NR uses dark frame subtraction to generate noise reduction. "</em></p>

<p>Lex,<br />Dark frame subtraction is something else, during long exposure some pixels will become saturated and thus appear as bright dots, in order to identify these pixels camera takes a secondary photo with identical exposure time but with shutter closed and then subtracts the values of such pixels this is also known as long exposure NR and is not unique to Expeed, this is applied to RAW data and it is only applicable if proper function is set in camera. Once the shot is taken it is not possible to perform long exposure NR later if the dark frame was not recoded immediately after the shot. Note that this is also different from dark current subtraction which is common for CMOS sensors.<br />Expeed NR refers to High ISO noise reduction which is removing the effect of pixels that have random values due to electronic noise. This is only applied to JPEG files and RAW data remains intact.</p>

<p><em>" If you choose the in camera noise reduction settings these will be applied to both exported RAW and JPEG files"</em></p>

<p>

<p>Richard, it is not possible to apply noise reduction to RAW data, RAW data is just a series of intensity values recorded from each pixel, only after or during demosaic it is possible to apply a common noise reduction filter. When shooting in RAW with NR=ON camera tags the RAW files and noise reduction is later applied in the RAW converter. You can nullify NR at any point if you shoot in RAW.</p>

</p>

<p>Arash,</p>

<p>Pretty technical. Thanks for the insight. Actually, I thought I read somewhere that Nikon does some noise processing before the RAW file leaves the camera, and I wanted to know if anyone had verified this. </p>

<p>For me, the end user, what that would mean is this...am I better off shooting jpeg for existing-light captures (taking full advantage of the D700's capabilities), or will I get the same resultant file shooting RAW in existing light? I'm just talking about noise characteristics now, not DR, color, exposure headroom, etc. </p>

<p>Thanks. I'm a shooter who isn't afraid to use a good, big, sharp jpeg if I have to. My files are rarely manipulated, and I try to nail the exposure in-camera. I'm a chrome-shooter!</p><div></div>

<p>Arash, just about everything you say is right on. The one statement I'd have a minor quibble with is</p>

<blockquote>

<p><em>With RAW your computer's Intel Core 2, Core quad or Core i7 becomes the "Expeed" processor with far more firepower than the small chip in the camera</em></p>

</blockquote>

<p>When it creates a jpeg from RAW data, the Expeed processor seems to blast through the steps of applying white balance, sharpening, saturation, contrast, brightness, and compression far more quickly than any desktop that I've used. The Expeed processor does these steps whether or not a jpeg file is saved because there is always a jpeg preview embedded in the RAW file.<br>

I've always attributed the efficiency of the Expeed processor to the image algorithms coded in silicon instead of the software run by the general purpose desktop CPUs.<br>

And undoubtedly, the Expeed processor has more horsepower per watt. This is a very good thing for battery life.</p>

 

<p>David -</p>

<p>Since you already said you don't use Capture NX, if you shoot RAW, you will not get an <em>identical </em> jpeg file.</p>

<p>With respect to noise only, are you better off shooting in-camera jpegs only? Probably not. If you shoot RAW, you can tweak the noise reduction in post-production, whether it be in LR, Aperture, or other processing program or add-in of your choice.</p>

<p>The general consensus is that in-camera NR is applied to jpeg files but does not affect RAW files. Only Nikon knows for sure, but it would be easy to shoot a low light scene with high ISO using NR on and NR off and see if there's a difference. (Note: When doing the experiment, you have to download the RAW file to your computer. In-camera image previews do have Expeed processing applied and are an unreliable indicator of the RAW file.)</p>

<p> </p>

<p>Tom,<br>

It is true that Expeed can perform some operations more efficient than a desktop chip because it is an ASIC (Application Specific Integrated Circuit) so it is hard wired to perform some operations quikcer, but it can only perform a limited set of operations and the there are some compromises, the quality of a JPEG out of camera cannot match the one you can get from Capture NX2 or even ACR, DR is compromised and sharpness is usually poor for prints because the algorithms that are wired in Expeed are very basic, your desktop in return can perform far more complicated calculations... So I guess JPEG it is good for snap shots you want to put on the Internet but not for serious work. I have never shot a single JPEG with my D700. To get the best out of any DSLR there is really no escaping shooting in RAW.<br>

David, in terms of noise, NR is already applied to JPEG files and cannot be undone, with RAW you always have the option to apply NR with better quality to your liking when and if needed.</p>

<p>Thank you for the clear explanation, Arash. I was under the impression that the NR was applied to the RAW file also, but it makes sense that it is tagged to the RAW file and later applied in your RAW converter.<br>

Dick</p>

<p>Arash -</p>

<p>"<em>sharpness is usually poor for prints because the algorithms that are wired in Expeed are very basic</em> " is probably claiming more than you really know because I doubt you have access to the source code of the Expeed processor. No disrespect intended. Maybe you are an electrical engineer and know the inherent limits of an ASIC. (I know I don't)</p>

<p>Richard -</p>

<p>With ACR, you can pick an NR setting at post-processing time, but ACR probably ignores any NR tag that might be in the file. The only way to use the NR setting in the file is probably with Nikon software.</p>

 

<p>Tom, thanks, I use Aperture and I'm sure that I will not be able to find out how the RAW converter deals with the information from the camera for NR. But, I do find this stuff interesting and it's helpful to have a better understanding of what is occuring and where.<br>

Dick</p>

<p>Tom,<br>

More detailed discussion about image processing techniques is beyond the scope of this forum and requires some technical background, If you are interested in learning more about state of the art image processing for DSC applications have a look at the following article, you need access to the technical journal plus EE background but it is very informative.<br>

<strong>CRISP: Coarse-Grained Reconfigurable Image Stream Processor for Digital Still Cameras and Camcorders</strong> <br /> Chen, J. C.; Chien, S.-Y.;<br /> <a href="http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=76">Circuits and Systems for Video Technology, IEEE Transactions on</a> <br /> Volume 18, <a href="http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=4639430">Issue 9</a> , Sept. 2008 Page(s):1223 - 1236<br>

Regards,</p>

<p> </p>