High dynamic range?

Discussion in 'Digital Discussion & Q&A' started by D-50, Aug 22, 2006.

  1. D-50

    D-50 TPF Noob!

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    I was just looking at a post on this site by Andrew Brooks and his use of High Dynamic Range editing. does anyone know anything about this? Can you do it in Photoshop CS? How else can that type of look be achieved?
     
  2. Dom0803

    Dom0803 TPF Noob!

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    It's quite simple really.

    All a HDRI (I- Image) is, is a composition of photographs with different exposures, usually very dark to very light to acheive a perfect blend. All the photos need to be identicle though, and the more exposures you have the better the image will turn out to be.

    Read the wiki on it, it shall explain it well. http://en.wikipedia.org/wiki/High_dynamic_range_imaging
     
  3. D-50

    D-50 TPF Noob!

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    I have read about it but when when I look at the resulting photo examples they seem to have that dreamlike quality to them where things somewhat glow. Is that simply a result of the merge or has any other processing been done? If you look at the images on this site http://www.cambridgeincolour.com/cambridge-gallery.htm especially the one of the bench I would love to know how this look is achieved.
     
  4. Arch

    Arch Damn You! Staff Member Supporting Member

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    we've discussed HDR a few times before...... heres a link to one of them....

    http://thephotoforum.com/forum/showthread.php?t=52699

    But to answer your other question..... no CS cant do a HDR merge...... but CS2 can, and also Separate programs like photomatix.

    Also i didnt see any reference to HDR on the site you linked..... so my guess is he's not using it (also he is an experienced photog/editor)... so he's probably using a combination of other techniques. However HDR could be used to create a shot like the bench one.
     
  5. Dom0803

    Dom0803 TPF Noob!

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    I don't see him mentioning HDR anywhere, but they certainly look like HDR's

    You have to use programmes with log's in them to have an official? HDR, but I find if I have ten photos with ten different exposures, if I open PS and I use each photo as a layer with an opacity of 10 on each of them, it creates the same effect, and gives an efficient blend.

    I guess it's a cheaper method than CS2.

    EDIT:

    I looked at that guys site, and he definitley uses HDR.

    http://www.cambridgeincolour.com/techniques.htm
    http://www.cambridgeincolour.com/techniques_dynamic-range.htm
     
  6. Arch

    Arch Damn You! Staff Member Supporting Member

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    Blending 10 photos using opacity is not quite the same as HDR ;) ...... you dont get a 32bit image.
     
  7. Dom0803

    Dom0803 TPF Noob!

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    yea but it aint like $600 :p

    Tried out that Photomatrix mentioned earlier. Here's one.. slightly different about it though.. it's a poorly lit room and I'm limited to only two second shutter speeds as my longest, so it wasn't overexposed to begin with, instead correctly exposed.. so it kinda defeats the purpose I guess. :p

    [​IMG]
     
  8. benaccent

    benaccent TPF Noob!

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    can you post the gerated image on its own so i can see it better? cheers
     
  9. David

    David TPF Noob!

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    Here's an image I did some while ago, when I first tested the "Merge to HDR" function of PS CS2. The resolution is reduced for posting:

    Click here. (Comprised of seven images from 2 stops below to 2 stops above)

    The same image, taken using the auto settings on my Canon 20D, can be seen here

    Click here.

    Most tutorials I've seen only go through the actual merge to HDR process, however I find that some degree of tweaking afterwards is necessary to get the tones for each colour correct, and to make the image more balanced. I almost always run through the following steps afterwards:

    1. Duplicate the window and convert to lab, then select the lightness channel on the duplicate.
    2. Redistribute contrast with the Shadow/Highlight tool and stretch it into the midtones further. Keep an eye on the histogram before and after this step.
    3. Perform a curves adjustment on just the shadows so we can deepen them a bit without losing detail in the overhead light fixtures.
    4. Sharpen as required using smart sharpen or using a mask to highlight the edges of the image.

    (Thanks to Kevin F for his help with this.)

    Doing this to the above image produces this:

    Click here.

    I actually think I went a bit too far with the darkening of the shadows in this one, but the principle is sound. I also haven't gone into detail about the adjustments in the steps above, so if anyone wants me to, or would like some screenshots then PM me.

    Out of curiosity I tried using the merge to HDR function on some random images, one of which was the photo used above. You can get some interesting effects, but you need to choose your images carefully (using the exif data) to ensure that you have the necessary tonal range for the HDR process or PS CS2 will not allow you to continue with the merge. The result I got from this is here.

    I love HDR images, and have always rated the Cambridge in Colour site as one of my favourites. His techniques are excellent as are the images.

    Posted in case the above ramblings help with anyone's HDR process flow. IMO time consuming, but very worth while results, especially night scapes involving lighting.

    David.
     
  10. Digital Matt

    Digital Matt alter ego: Analog Matt

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    I just want to clarify something, since it seems to me that people are getting the wrong idea bout HDR.

    HDR is not a new thing. It's not a digltal-only thing. It's not software based.

    It simply means, capturing a higher dynamic range than the normal contrast range of the medium. It can be done with film, or digital, and has been done for many many years, long before photoshop and the "Merge to HDR" function.

    It doesn't require photoshop, or 8 exposures. It can be done with split and graduated neutral density filters. It's just a way to deal with a scene that has very bright highlights, and very dark shadows, much the way that the zone system helps to control this. For landscapes involving a bright sky, and a dark foreground, nothing more than a graduated neutral density filter, and one good exposure, are needed for an image that covers the entire "high" dynamic range. Understanding that will help you understand what you are doing with software, and what to do in the field, before you attempt it in post.
     
  11. markc

    markc TPF Noob!

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    One of the problems I have with some of the "HDR" image I see is the contast is rather goofed up along with continuity of tones. You can't just take the well exposed area of one image and plunk it into the blown out area of another image. There needs to be a smooth constant ramp from dark to light. If you have a spot of 50% grey in one image, and a spot of 50% grey in another image, they should not be the same shade in the combined image. They may looks like the same tone, but because they were exposed differently, they are different in the "real" world. When combined, one should be lighter than the other. That's why the layer method doen't work in my opinion.
     
  12. Digital Matt

    Digital Matt alter ego: Analog Matt

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    I agree Mark. The majority of images I see that are done with this newfound HDR method look really wrong to me. Completely unnatural.
     

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