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Adventures in the kingdom of HDR

Discussion in 'Image Processing' started by jamespetts, Sep 30, 2013.

  1. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    I have not tried HDR before, but gave it a go this evening: I went out with my E-P3 and a tripod and took some photographs of London's Tower Bridge at dusk (and only remembered as I was on my way home that the E-P3 had an "auto-bkt" option, after having taken all of the photographs manually adjusting the exposure in each one...).

    I used Luminance HDR to compile the images (based on the original .ORF raw files) into a single tone-mapped .jpg and, after some tinkering with the options, came up with this for one of the earlier shots of the evening (I have not got through all of them yet):

    10029156076_bf16f7f440_b.
    Tower Bridge at dusk by James E. Petts, on Flickr

    Meanwhile, to compare with an ordinary image, I processed one of the middle photographs in the same sequence in Lightroom, which gave me this:

    10029148934_ed9d816df4_b.
    Tower Bridge at dusk by James E. Petts, on Flickr

    I should be interested in people's views on: (1) which of the two is preferable and why; and (2) how to get the most out of Luminance HDR (and what I might have done better in the HDR version of the image).
     
  2. Trick question? But seriously, #2 any day of the week.

    I see the main reason for using multi-shot HDR or simply over-exploiting the single shot dynamic range of some modern cameras is to create an otherwordly effect which is what your example shows. Interesting to look at but not necessarily natural or pleasing. Expanding the dynamic range and removing too much natural contrast from an image requires a lot of processing to retain definition and avoid a washed-out look. This is what gives HDR images that "glow" as well as making them susceptible to haloing in areas of higher contrast. A good example of this is where the tops of the two towers meet the sky.

    If you like the effect then go for it. Personally I've never liked the look that the edge haloing that HDR creates so I always try to keep any dynamic range expansion to levels below where this starts to occur. Your non-HDR image looks amazing to me and I would be very happy to have come away with a shot like that.
     
  3. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    Definitely the second one. The first one is a bit too flat to my eye. Maybe a touch of fill light or lighten shadows on #2
     
  4. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    Thank you for your input! I am rather new to HDR, so have not quite mastered all of the settings yet - which settings does one need to alter to reduce the halo effect?

    The interesting thing is that the way in which I processed no. 2 was based on the way in which no. 1 turned out, as I was trying to match them and see what could be done with Lightroom's tools as far as making a non-HDR image appear to have an HDR effect was concerned.

    The settings for the second one are:

    WB: as shot (in-camera auto)
    Exposure: -0.44
    Contrast: -74
    Highlights: -76
    Shadows: +70
    Whites: +29
    Blacks: -3
    Clarity: +100
    Vibrance: +52
    Saturation: +33
    Blue saturation: -44
    Camera calibration: Huelight CF Standard

    Plus a graduated filter at the top (for the sky) and another at the bottom (for the water), the sky filter having lower exposure but greater highlights than the rest of the image.

    An interesting technique to create HDR-like images seems to be to reduce the contrast and increase the clarity by a very great amount, together with controlling shadows and highlights and increasing saturation/vibrance.

    The image looks very different indeed to how it looks with default settings.
     
  5. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    The Mantiuk06 algorithm always seems to create too way out results for me. I prefer Fattal mostly. Especially when I want to get "normal" results in very contrasty situations. The Fattal default settings in Luminance are less spacey. I see from the Exif pre-gamma value that you did some experimentation already. There are a lot of parameters to experiment with, where you need to remember which was which, in order to master it. Which is why I play safe.
    This one was done in Mantiuk08 in order to pull up the dark flower centres. I did contrasty ones, but this looked calmer.
    <a href="http://www.flickr.com/photos/27779069@N06/9763605633/" title="P9080231- HDR1_v1 by ianp5a, on Flickr"> 9763605633_07896fc9b2. "369" height="500" alt="P9080231- HDR1_v1"></a>
     

    Attached Files:

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  6. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    Thank you for your feedback. I have had another go this evening with my another set of photographs that I took, this time using the Mantiuk06 and Fattal algorithms, as well as a single exposure post-processed in Lightroom. Here are the results:

    Mantiuk06
    10045244384_41e5cc2c47_b.
    Tower Bridge in twilight by James E. Petts, on Flickr

    Fattal
    10045388196_3106640903_b.
    Tower Bridge in twilight by James E. Petts, on Flickr

    Single image/Lightroom
    10045388595_db8c0dd0c8_b.
    Tower Bridge in twilight by James E. Petts, on Flickr

    I note that the Lightroom version has something of an unfair advantage because the RAW processor in Luminance HDR does not seem to take account of the lens corrections as the RAW processor in Lightroom does, although what to do about that is unclear (I cannot imagine that reducing each image's dynamic range by exporting them all to JPEG first would help matters at all).

    I should be interested in people's views on this. I suspect that the single image still looks better, and I am not at all convinced with the Fattal result (although I am finding it challenging fully understanding what the sliders mean in that algorithm - any tips as to how to set it up would be appreciated).
     

    Attached Files:

  7. The HDRs both seem to lack clarity and/or sharpness. I'm wondering whether you've chosen the right test subject to attempt HDR because the single shot image seems to have done a better job of showing shadow detail than both HDRs and doesn't push the highlights as far as the second. The scene hasn't exceeded the sensor's dynamic range so the only reason to use HDR here is for effect.
     
  8. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    Yes, I noticed the sharpness thing, too. I am wondering whether this is because Luminance HDR does not do sharpening properly or at all. Does anyone here have experience of Luminance HDR that might be able to assist with this?

    I think that you are also probably right about the choice of subject - the single image does so far in both cases look better than the HDR images. I have never tried HDR before, so wanted to test out what it could do, but so far, I have not found it an advantage over using whatever dynamic range can be found in a RAW file, even of the older generation sensor found in my E-P3.

    What do people here find are subjects that require/benefit from HDR? I decided to start with Tower Bridge because I had seen some lovely HDR images of Tower Bridge on Flickr (this one in particular), but perhaps I could get as good an effect with an ordinary single image for that subject at least.
     
  9. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    For the first set, I like the sky in the HDR (clouds are one of the fun things about HDR), but the tower itself and the background both look blurry. Wondering if the tripod was stable enough, or shutter shock was in effect. If you look at the crane on the left, you see quite a bit of "fuzz". As far as the second set, the colors are more saturated (the purple on the tower and the sunset). The second image looks like it was taken earlier than the single image (based on relative light in the photo). Neither one looks bad, the single one just has more of a twilight look.

    FWIW, this is what jumped out at me.
     
  10. Multi-shot HDR was originally conceived to be used in scenes that have overcome a sensor's ability to record the full dynamic range in one exposure; anywhere that a single image would result in blocked shadows and/or blown highlights. As far as selecting subjects, it boils down to a choice of whether you are looking to use it expand your camera's DR in high contrast scenes or use it for artistic effect.
     
  11. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    Hmm - how might one know in advance that a certain type of subject might require multi-shot HDR so that one knows when to bring a tripod...?
     
  12. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    Thanks for the update.

    You can use hand held bracketing. I end up doing that because I suddenly see a scene that has extreme lighting conditions.

    Regarding your pictures, I presume you are using the align function. Even on a tripod they may be 1 pixel out. And thus cause fuzziness if not aligned.

    Regarding hand held bracketing, I rest/hold the camera somewhere so that there is no "rotation". So even if the camera moves a few pixels, auto align can snap them together., But if the hand held camera rotates ever so slightly, that will mush up your pixels.
    I does not matter if you reduce each pictures DR. As each picture is supplying a slice of DR to make up the full Range. If you are worried, make more, in between shots in the bracketing. I am quite happy using 3 JPEGS so far. But perhaps I will experiment with 5 shots and compare.
     
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  13. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    Thank you for the helpful tips, especially about alignment, which I shall bear in mind. As to the number of images - most of these were made with ten images each a third of a stop apart.
     
  14. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    Whenever I've tried HDR before I've similarly been not too impressed with the results when compared to squashing DR on a single shot. The Oly 16Mp sensors give excellent latitude on shadow pushing though, so perhaps it's not too surprising. Try doing it with a Canon sensor!
     
  15. DHart

    DHart Mu-43 Hall of Famer

    Jan 7, 2010
    Scottsdale, Arizona
    Don
    As Nic mentioned a couple of times, HDR is traditionally used to capture image data that exceeds the sensor's abiity to capture in a single image.

    When you have moderate to relatively flat lighting conditions, without exceptionally dark shadow areas nor exceptionally bright highlight areas, HDR capture is generally not needed. Just make a good RAW exposure and then lift shadows or recover highlights, as desired, in post. The latest sensors in m4/3 bodies are able to provide great capability in this regard, when working with a RAW capture. Starting with a RAW capture is especially important in doing this kind of thing, as JPGs have been stripped down from full data to a much more confining set of data to work with.

    But when you have an especially contrasty situation, where, for example, there is direct sunlight on part of the scene, and deep shadow areas in another part of the scene... and you want to have useable data in both of these extreme areas, this is where capturing bracketed exposures and processing them for HDR can yield results with great detail in both the highlight as well as the shadow areas.

    Overcast days tend to not make for HDR conditions, as the contrast is low to begin with. Bright, contrasty sunlit scenes which also have dee shadow areas... as well as indoor settings where bright outdoor areas are also visible tend to be good situations to employ HDR techniques if you want to reveal details in both the bright sunlit areas as well as in the dark shadow areas.
     
  16. jamespetts

    jamespetts Mu-43 Top Veteran

    802
    May 21, 2011
    London, England
    I am aware of the normal purpose of HDR; but I suppose that I imagined that it would have been useful in this situation whereas it seems that a single exposure, even with the older 12MP sensor in my E-P3 (not the later 16MP sensor as suggested above), has captured enough dynamic range for the photographs that I have so far processed.

    One relevant thought that I had was that, if I was taking photographs of objects lit predominantly with artificial light at night, then the shadow noise in the darker areas might be excessive without HDR (and the areas well lit by artificial light might have blown highlights with a longer exposure). Is that a sensible situation in which to seek to use HDR? I have yet to come onto processing the photographs that I took later that evening when the sun went down fully.
     
  17. angusr

    angusr Mu-43 Regular

    79
    Sep 21, 2011
    I'm no expert on HDR, and I'm looking at these on my phone so have missed the subtleties others have mentioned (might have missed them anyway...). However I quite like the HDR version because this is such a familiar image that it needs something different doing to it. The HDR version made me stop and look. Photo 2 is a nice example of a shot which has been taken millions of times. Photo 1 has at least only been done a few thousand!

    Sent from my Nexus 4 using Mu-43 mobile app
     
  18. Mattr

    Mattr Mu-43 Regular

    62
    Aug 5, 2013
    Melbourne, Australia
    Matt Robinson
    Firstly, the shots are great in themselves and stand up well. The base issue is, as mentioned by others, that the scene was captured quite adequately by the sensor. Therefore HDR hasn't really added that much more. Scenes where I've seen this technique work best are generally landscapes on a day when rain or storm clouds are clearing to reveal sun. In otherwords, contrasty.

    Also, how many shots did you take in each sequence? To get a more impressive HDR you need to capture across a wide range in the source sequence so usually 5 or so shots are required so that you capture tone information from the deep shadows through to highlights.

    Matt

    Sent from my GT-I9100 using Mu-43 mobile app
     
  19. DHart

    DHart Mu-43 Hall of Famer

    Jan 7, 2010
    Scottsdale, Arizona
    Don

    In the case of this original situation, yes, a single exposure, with a sensor having good dynamic range, would probably have yielded a wonderfully useable file.

    As for the situation with bright artificlal lighting, at night, with deep shadow areas... absolutely... bracketed exposures, subsequently processed with HDR technique, would likely be quite appropriate to ultimately result in a final image revealing a broad dynamic range of image data.
     
  20. mattia

    mattia Mu-43 Hall of Famer

    May 3, 2012
    The Netherlands
    The lighting there doesn't require HDR - perfect time of day for a longer exposure single shot that will capture the mood and detail in a single shot. Where I've used multiple exposures successfully is extremely high contrast scenes. Landscapes with bright sunlight that mean you either get a nicely exposed sky with cloud detail, or a nicely exposed foreground. Interior shots with very bright light coming in through windows, blowing out details. And even then, I always check to see what I can get out of a single shot first, because it avoids any issues with items in the scene moving between shots.