jpeg vs raw exposure differences - why?

Discussion in 'Nikon' started by dave_dube, Sep 16, 2006.

  1. Last weekend on a family trip to Southern Oregon, I had my D200 for general
    shots. There was a lot of sun glare on my LCD screen and I accidentally
    changed the quality to Raw and jpeg. While comparing the files side by side,
    the raw files were consistently underexposed compared to the jpeg files. At
    first I thought it was due to the larger raw file size and added data but now
    I'm not comfortable with that conclusion. Some of the raw files are
    significantly underexposed compared to the jpeg file.<P> Would the above be
    considered normal and expected? If not, thoughts?<P> Thanks for any comments,
    Dave
     
  2. Haven't noticed it quite as much as I think you have on the D50, but it might be an issue... Is
    it possible that the raw conversion in the computer is at fault? I hope someone chimes in on
    this who really knows, because I'm really curious about this issue, too.

    What software are you using for opening/converting the raw files?
     
  3. the most likely reason is that the jpegs are processed in camera according to the camera
    settings while the NEF files are not.
     
  4. Raw files are all the information that the camera had at its disposal at the time of exposure. The JPEG is the camera deciding, what in the photo will look the best when viewed the first time by anyone looking at the file.Raw files are not the finished product, and should look a little under-exposed compared to a in camera JPEG. When you process the RAW file,that is where you get its advantages, not in its RAW state.
     
  5. OK Peter, your question was one I hadn't thought about.<P> I had opened and viewed with Adobe Bridge. After reading your question I went back and opened in iView. <P>Interestingly, in small thumbnail size the exposures look identical. In expanding the view to make sure, the jpeg photos are crisp and clear while the nef files are blurry. So, what's that all about? Could it be the same issue but being expressed differently by the alternate software? There is obviously and issue between the 2 file types for the same photo but translated differently.
     
  6. Raw files tend to need some work done during conversion to make them look good. They almost always look flat, dark and a little soft. This is why some people don't like shooting RAW, too much work. Jpegs are corrected in camera and come out generally looking good.
    As was stated above, all the information is in that Raw file, but work must be done to bring that image to life.
     
  7. Ellis and Michael, that's what I had been thinking but now (refering to the blurred images of nef files in iView)? Same reasoning?
     
  8. Yes it is the same reason: The jpegs are beig sharpened in camera (according to your
    settings) and the NEF files are not sharpened. Get a copy of "Photoshop CS2 RAW" by
    Mikkel Aaland or "The DAM Book" by Peter Krogh. Both do a straight forward job of
    explaining what is going on.
     
  9. Thanks everyone! I won't spend any time wondering how many raw photos I deleted in iView thinking they were soft. Luckily, I just got the software a couple of weeks ago and still rely on Bridge for my inital culling.
     
  10. Here's a test... (I've done this, maybe others have too)

    Shoot an image as the best Jpeg file your camera can make. then shoot an identical image
    as a raw (same exposure... everything)

    Now leave the jpeg alone, but open the raw file (And my favorite part... try a different
    white balance! Shade or Cloudy sometimes makes a big difference), tweak taht raw file
    with a little levels or curves, perhaps a TEENY bit of sharpening (unsharp mask actually). I
    do this in 16-bit mode myself and use no "automatic" features in leveling, curves. Then
    save out a jpeg from that if you wish.

    NOW... compare... if you're like me, you'll find the raw image tweaked (I only spend a few
    minutes doing this usually) is way better than the in-camera jpeg. that's why I shoot raw...
    (although if I'm shooting a bunch of candids I'll sometimes just shoot jpeg...

    The raw files look very flat when they come into photoshop, but with VERY little work, they
    can be made to look downright stunning, moreso, I think, than jpegs.

    Sometimes people say this is cheating, especially when you separate the foreground and
    background and treat them differently. I can only assume such folks are unaware of just
    how much of the beauty of the photos of folks like Ansel Adams happened AFTER the
    picture was shot... in the darkroom...
     
  11. Mind that Bridge defaults to auto-exposing your NEFs, which will expose for the highlights in
    the file (making them look underexposed). Try using Adobe Camera Raw instead of judging
    by the initial thumbnails.
     
  12. &#147;While comparing the files side by side, the raw files were consistently underexposed compared to the jpeg files. At first I thought it was due to the larger raw file size and added data but now I'm not comfortable with that conclusion. Some of the raw files are significantly underexposed compared to the jpeg file.&#148; --Dave Dube

    Your NEF files are probably not under exposed but rather suffer from inappropriate gamma, something that is easily corrected in software. A curve to raise the gamma is likely part of the in camera processing of your JPG images.

    Look at the histogram. Is there clipping of the shadow area in your NEF images? If not they are not under exposed. Is there clipping in the highlights? If not your images are not over exposed. This is general, if the image values are bunched up at the low or high end though not clipped you could have a problem. Otherwise the mid-tone values are too low (as probable in your case) or too high. This is correctable with levels and curves.

    Do Not Use brightness and contrast to correct gamma problems. These are lousy meaning they cause clipping and loss of data. If you need to do some clipping use Levels where you have a histogram and proper control.

    Best,

    Dave Hartman.
     
  13. It seems that many third party Raw converters do not apply the in camera sharpening and some do not even apply the in camera white balance so the uncorrected files look worse than JPGs from the nikon camera. Nikon Captue seems to apply these settings and seems to produce less noise from NEF fliles than other RAW converters. I am trying Adobe Lightroom at the moment but it seems that RAW canversions are more noisy then conversions from Nikon Capture. If you want the best RAW conversion fram NEF files Nikon Capture seems to offer better images.
     
  14. I just purchased a new retail box Nikon Capture NX on ebay. The advantage of this is you get
    the CD with both the Mac and Windows version, rather than paying for one version online.

    I have done extensive testing of Capture against Photoshop CS2 and Capture consistantly has
    better reds. It also does better with reducing the "jaggies" for lack of a better word for them.
    Photoshop CS2 may have more shadow detail, but overall I prefer Capture NX.

    Dave
     
  15. David H - your gamma suggestion has taken care of my issues with this bucket of photos and my future with RAW files. As much time and finesse that I have with PS, I've never used the gamma function (much to my loss). Thanks David for instructing me on the value of gamma. It wasn't really my question or concern but was a great bonus for my posting.<P> Thanks to all that have presented ideas, all valuable information and worthy of exploring. It's like, which previews from which software do I trust as being the most accurate representation of the file.
     
  16. I just realised how dumb my response to gamma was. Of course I use it all the time in Levels. This was the first time I used it under the Exposure Image adjustment and like it a lot with the 16 bit images. I'll have to try it in the Merge to HDR feature with 32-bit photos. Anyway, thanks again, Dave D.
     

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