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Unsharp Mask: Everything we ever wanted to know about it

Discussion in 'Nikon Capture and View NX' started by Mike Buckley, Sep 3, 2008.

  1. The purpose of this thread is to learn everything there is to know about Capture NX's Unsharp Mask (USM). It is very different from Photo Shop's USM, which is particularly important for those of us who migrated from Photo Shop to Capture NX. Feel free asking questions and providing answers.

    This first post is a general collection of resource materials that I'll update as we become aware of new information.

    Capture NX 2 User Manual
    Click here to access the manual.

    Sharpening Tips in Tutiki
    http://tutiki.org/w/index.php/Nikon_NX_Sharpening_Tips

    Capture NX Help Screens about USM
    GENERAL DESCRIPTION OF USM
    "The Unsharp Mask tool increases the apparent sharpness of your images by enhancing the edges of objects in your image. The Unsharp Mask tool in Capture NX 2 is unique in that it always applies its sharpening to the luminosity of the image, which prevents any unwanted color shifts."

    COMPARISONS WITH PHOTO SHOP'S USM
    "Unsharp Mask sharpens edges without affecting color balance by making adjustments only to luminosity (brightness). The effect is the same as performing Unsharp Mask with the Luminosity channel selected in the Adobe Photoshop Lab color model. If Unsharp Mask is applied to a single channel, such as red, the values for ab (chrominance) are used to determine what points in the image are red, and masking applied to the Luminosity channel for those points only. An intensity of around 20% in Capture NX 2 is roughly equivalent to 100% in Adobe Photoshop. No sharpening will be applied if Intensity is set to zero. Intensity must be set to at least 1% if sharpening is to apply."

    INTENSITY PARAMETER
    "The Intensity slider controls the amount of sharpening that will be applied to the color selected by the Color pull-down menu. The higher the sharpening intensity, the more pronounced the sharpening effect will be on your image. If the intensity setting is set too high, it can create an over-sharpened and artificial looking image."

    RADIUS PARAMETER
    "The Radius slider enables you to increase the reach of the sharpening effect. The higher the radius setting, the wider the edges will appear in the sharpen image. A radius setting that is too high will produce visible halo artifacts, which can appear as white outlines around objects."

    THRESHOLD PARAMETER
    "The Threshold slider is designed to limit where sharpening is applied with the current settings. The higher the threshold setting, the less that objects in the image will be sharpened. This slider works to indicate how much of a difference between one pixel and its neighbors is necessary in order to apply sharpening. This slider is helpful in preventing smooth areas from picking up noise artifacts, such as when sharpening skin areas or landscapes with large amounts of sky. Too high a threshold setting will prevent any objects from being sharpened in the image, so it is important to find a good balance."
     
    Last edited by a moderator: Sep 4, 2008
  2. Thanks for this Mike.

    It is usually a trial-and-error approach for me where I disable all in-camera sharpening in NX2 and use the D200 capture settings from Jason Odell's e-book as my first processing step. If necessary some USM or High-pass sharpening at the end and some USM when resizing for the web.
     
  3. Thanks for posting this and the tutiki link which I'm going to print out.

    I always seem to oversharpen with USM and have been trying the high pass sharpening.

    Do you sharpen (USM) differently if you are going to resize and post to the web as opposed to sharpening for display or printing?


    MikeT
     
  4. You don't know what oversharpening is until you see some pictures I first made from scanned slides and had know idea what I was doing. Thankfully, Uncle Frank rescued me from those ridiculous practices.

    There are a few tips that have apparently been used since the beginning of digital photography that will ensure that you don't oversharpen. Examine sharpening results at 100% viewing. When sharpening portraits, look in the hair and eyes for artifacts. In dark areas of any photo, look for exaggerated noise. In all photos, look for halos (bright white lines) where dark areas are adjacent to light areas, such as where foliage on trees meets a clear blue sky.

    The answer to your last question depends on workflow. I always create a "Master" file from which all other files such as web output and prints are made. My Master is a NEF that is usually sharpened at 50/5/4 as a starting point. I will sometimes apply USM as high as 55/8/4 and as low as 40/5/4. I am intrigued by Tom's comments and would be crazy not to try his ideas out considering his expertise, which is what this thread is all about.

    When creating a JPEG for web output, doing so requires dramatic resizing. Any time a file needs to be dramatically resized up or down, it will need to be sharpened again but just a tad. When using Capture NX, I use 10/5/0. I became so confident with that setting that I don't bother checking it; I apply it across the board to all photos. That's mostly because viewing on the web involves such a small file being viewed using monitors which have such low resolution that small variations in USM for web output don't seem to make much difference. Taking all of that into account, it doesn't seem worth the time to me to custom resharpen for web output.

    For the record, I no longer use Capture NX to sharpen for web output. Instead, I use my DAM product (IDimager) to do that. It's much faster because, unlike Capture NX which sharpens the NEF itself, IDimager sharpens only the large high-resolution JPEG preview that is part of all RAW files. That works fine for web output, noting the limitations mentioned above.

    I have done so little printing that I look forward to learning from others how best to handle them, so I have no comment about that.

    I'll get to Tom's post later in the day.
     
    Last edited by a moderator: Sep 4, 2008
  5. If anyone knows how to obtain an electronic file of the Capture NX or NX2 manual, preferably the latter, please provide a link. I can't find either of them at Nikon's website. I would like to look stuff up about USM.
     
  6. Does this work, Mike ?

    Ronnie
     
  7. Perfectly! Thanks, Ronnie!
     
  8. I think you mean that you leave your in-camera sharpening as is and add the USM to that. If I understand you correctly, it's understandable that anything greater than 30/5/0 would be problematic. The parameters in Jason's books assume that you turn off all in-camera sharpening.

    For me, the biggest argument against leaving the in-camera sharpening in the file is that doing so requires us to leave it throughout the entire image. There is no opportunity for camera-based local sharpening.

    I'll get back to you about the USM parameters compared to Photo Shop's parameters once I read stuff in the manual. HINT: The stuff in the help screens corroborates my statements. :biggrin: Hopefully the manual will be more helpful.
     
  9. I find on 99% of my images, the setting of 4 in NX2 is just right for my global sharpening set and then when I have finished and cropped I go back and use NX2's high pass sharpening selectively. I then use Nik sharpener, via CS3 for my output, to print, sharpening step. Works a treat for me!.

    Cheers
    Nancy
     
  10. Not at all, Tom. The only thing the helpscreens offer is that NX's Intensity of 20% roughly equals PS's 100%. They don't imply, much less state, any other relationship between NX and Photo Shop. To infer that the relationship between all of NX's and Photo Shops's numbers are a 1:5 ratio is not supported by any documentation that I have seen.

    When conducting a search on "Unsharp Mask" in both the helpscreens and the manual, the two documents are exactly the same, word for word.
     
    Last edited by a moderator: Sep 4, 2008
  11. Commodorefirst

    Commodorefirst Admin/Moderator Administrator

    May 1, 2005
    Missouri
    I will note, since I wrote the tutorial last year, I have changed my sharpening methods quite a bit with the D300 camera and some with the D3 also.

    Before I got NX2, I had started to do specific brush work on bird images taken with the D300 and sharpening the primary subject only, to avoid grain and artifacts in the sky areas. I selected a starting setting, (a lot of the times, 21, 11, 4) and applied it then selected the brush tool and applied it only to the primary subject. Once in a while I also did some high pass work, also applied with a brush.

    I keep my D300 at 4 as a pre processing first pass sharpening system as mentioned above.

    For portraits I am also using in NX and NX2 the high pass filter with a brush for features, and the eyes, and also 10, 35, 10 for eye pop selectively applied to the eyes too.

    Before NX I was a lab sharpening person in CS, and with the advent of NX I was happy to see the sharpening occuring as it does in NX and NX2
     
  12. Thanks for your reply tom.
    I had been using Jason book for USM as a starting point with 50/4/3 (I think) and sharpening looks fine with no halos. Then after resize for web I had been using 10/5/0 which at this point I can't tell if I have halos or not. I then save the image as a jpg and look at it with windows picture viewer and I can see areas of over sharpening. Either my 50/4/3 is too much or the final output sharpen is too much. I haven't experimented much with this to determine the best settings yet.

    Interesting you have in camera sharpening set to on. I also have mine set to on as well.


    Thanks for your reply MikeB
    I haven't read the rest of the threads yet but me too!


    Pretty much the same settings I have been using.

    Same here MikeB. I have a few images worth printing.

    Edit: I hope you don't mind me calling you MikeB.

    MikeT
     
  13. Wade,
    First thanks for posting your tutorial. I printed it out and gave it a good read during my lunch hour. Now that you have changed your sharpening strategy, do you sharpen more aggresive or less?

    MikeT
     
  14. The same settings, but yours are applied in addition to in-camera sharpening. My in-camera sharpening is eliminated before applying those settings. That explains for me why you're getting halos.

    Call me anything you want. Nobody knows better than you and I that our first name is just another four-letter word. :biggrin:
     
  15. FWIW, I've had pretty good luck using a +6 setting in my D300 and then simply apply 10-5-0 (and occassionally more, see below) before I save as an 8-bit 3600 x 2400 master (12 x 8 @300dpi). I translate to web using photomechanic, resized to 900dpi. This program will add slight additional sharpening (or not, my choice) in going the web size.

    Their are two places the 10-5-0 doesn't work. One is a shot with a lot of smallish foliage leaves in it...in this case I increase the Threshold parameter to somewhere between 2-5 to smooth out the leaves. Another is with a broad surface with only minor intenisty or brightness differences....to avoid postering, I just increase the threshold to smooth it out....usually 5-7 is sufficient.

    I have noticed that when I switch to the D50, I have to increase the Threshold to 1-2 as well, to get equivalent results to 0 on my D300.

    The main advantage of this system is that only one paramenter usually has to be changed, and as Mike points out, it is easy to do a macro in NX to apply the sharpening to all prints.
     
    Last edited by a moderator: Sep 4, 2008
  16. I think I had this sharpening problem before I turned on in camera sharpening.
    I have read on the net that so-and-so from Nikon says that in camera sharpening should be turned on reguardless if you shoot jpg or raw to overcome the anti aliasing filter. Just in case this fellow knows what he is talking about, I turned mine on to a 5 for testing. My first thoughts were to use a much lower USM since I'm leaving camera sharpening on during post.



    LOL! That statement made my day! If we get any more Mike's in here, we're in trouble. :biggrin:
    Thanks MikeB


    Another with in camera sharpening turned on. Very interesting indeed! I'll try some of your settings Harry to see how they work for me.
    Thanks Harry,

    MikeT
     
  17. Nah. All the Mikes will just run everyone else outta here and we'll keep the place to ourselves. :biggrin:
     
  18. Nice to see you, Wade! I was hoping I wasn't going to have to get my big hook to drag you over here. :biggrin:

    My apologies for putting the link to the NX 2 manual above your tutorial in the first post of the thread. Call me red-faced. :redface:
     
  19. I don't think so!!
    o050.gif
    Subscribe to see EXIF info for this image (if available)


    Being a rookie, I'm finding this conversation very interesting. I originally oversharpened everything. I've been finding my way with experimentation though & this thread is helping out quite a bit. Thanks for opening it, Mike!
     
  20. Eye Pop Parameters

    If you don't think there are a lot of ways to accomplish similar results, consider the recommended USM parameters for sharpening eyes.

    Wade (Commodorefirst): 10/35/10

    Odell: 65/6/2

    Nikon: 15/11/9

    Pick your poison!
     
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