EDR, Just what is it

Discussion in 'Beyond the Basics' started by Battou, Apr 8, 2009.

  1. Battou

    Battou No longer a newbie, moving up!

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    EDR is a term I've been using for quite some time, but I never really thought to get into a detailed explination until I saw the term used word for word in the review of a camera capable of in camera basic EDR processing mistakenly pointed out as supposed to be capable of internal HDR processing.

    Extended Dynamic Range processing or more commonly known as Tone Mapping is commonly confused for HDR or High Dynamic Range processing. Extended Dynamic Range is not High Dynamic Range, they are different. EDR in it's truest sence merely pushes the dynamic range to caputre some details to create a more nutral representation of a scene with extreams by suppressing hard contrasts where as HDR pushes above and beyond that to reproduce the full range of light intensities present in natural scenes, often to a point of exadgeration beyond that the human eye can naturally percieve.

    There are two issues here with people simply refferring to EDR as tone mapping, the first is tone mapping being a major factor in the display of true HDR's. The second is the similarity in methoed used to create it along with the common uses.

    To display an HDR on most media including (but not limited to) computer moniters it's required they be tone mapped and compressed into in image that can be read from three, five, seven, nine or more images. The most common methoed of creating an EDR is essentially the same as HDR but using one or two LDR base images through the use of Photoshop (and the like) and Photomatix (and the like). This creates an incorrect assumption that tone mapping is HDR reguardless of the base. The difference is that an EDR can be created and displayed from a single image without the use of HDR software by playing with light curves and other photoshop comands where as a proper HDR can not.

    EDR processing is used for several different things, all of them are shared with proper HDR processed image uses. Below are some examples and a brief discription of three of the most common EDR useage:

    To emulate HDR from a LDR image in an attempt to reproduce the full range of light intensities present in natural scenes. This process commonly uses one exposure manipulated into three, five, seven, or nine images with different exposure. Thes are commonly refered to as fake HDRs easily discernable with thier disteinct lack of contrast and exadgerated colors and noise, digital fake HDRs often have halos due to missing information that did not exist in the original file that would normally be there with the correct number of proper exposures* used in HDR.

    Below are some examples and a brief discription of EDR useage.

    An example of a fake HDR created with five scans of a single film frame
    [​IMG]

    and here is the scan of the frame as shot
    [​IMG]

    The second use of EDR is to suppress hard contrasts to balence exposure, these are harder to detect because they only exadgerate light and dark but knowing the limitations of digital censors and film they can be spotted. This is what I feel is the truest EDR form by extending the dynamic range of a single exposure and compensate for exposure extremes.


    An example of a EDR created with five scans of a single film frame
    [​IMG]

    and here is the scan of the frame as shot (cropped to match)
    [​IMG]


    And the third being to push color and contrast keeping the dynamic range low, These are by far the most dificult to spot as there is no exadgeration, just an LDR push of what is already there.

    An example of a LDR push EDR created with five scans of a single film frame
    [​IMG]

    and here is the scan of the frame as shot
    [​IMG]


    And again, all of these can be created in Photoshop alone provided one has the experience to do so.

    Any Questions?


    *proper HDR Exposures - Contrary to popular belief, a proper HDR exposure is not a guessing game that can simply be created with the shutterspeed dial or exposure compensation, metering of all luminances between light and dark areas of a scene is needed to accuratly expose for them. A real HDR can be done simply by adjusting shutterspeed or exposure compensation but there will generally be some minute and generally undetectable inaccuracy and information loss.
     
    Last edited: Apr 9, 2009
  2. Garbz

    Garbz No longer a newbie, moving up!

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    Can I simplify that for you since some people won't read past the longer words:

    HDR from 1 image, is NOT HDR!

    :)

    p.s. Battou you're fighting a losing war here. I have been saying this for years, but people still refer to single frames tonemapped as HDR :(
     
  3. Battou

    Battou No longer a newbie, moving up!

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    I know, so have I. I am kinda hoping that maybe, just maybe if I can explain a more appropriate term that is as easy to say and type as HDR maybe they will use it. I just wish I had some HDR's for comparison so they could see the difference.
     
  4. Mike_E

    Mike_E No longer a newbie, moving up!

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    Nuklar is Nuklar, taint no other way around it. ;)
     
  5. ann

    ann No longer a newbie, moving up!

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    it's enough to drive one to drink.

    gosh is it after 5 anywhere this moment. (3:20 EST-not tonedmapped).
     
  6. Arch

    Arch Damn You! Staff Member Supporting Member

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    This is basically all correct, and like Garbz i'v been banging on about this for years...

    However, fake HDR's are not really that easy to spot as mentioned, because of halo's, colour or even contrast... but more by skill of the processor.

    These issues can occur on 3 even 5 image HDRs too if the person doing the editing either wants it that way, or doesn't have the skill to avoid it.

    I'v seen some pretty good tone mapped images and some pretty poor HDR's (and vice versa of course) and alot of it comes down to control.

    The times where a tone mapped image trying to be HDR will fail is when the range in the scene is too high.
    This of course, is what HDR was created (well added to photography) for... to capture scenes with huge dynamic range.... nowadays its often used for pics of simple landscapes and all sorts.

    One other area where real HDR tends to stand out from tone mapped 'EDR'S' tho is with reflections.

    For example, if you take several exposures of a car inside a garage with a single light source, you will get a varied degree of detail within the reflections on the car depending on your exposure. So when the images are combined...'Shiny!'
    It would still look quite dynamic with a single RAW conversion, but the reflections on the body work will just not look the same.

    There is a time and place for both methods, so neither are wrong, but they are also very different in their uses and limitations.
     
  7. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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    HDR from 1 image is like Military Intelligence or an honest politician. It Freaking Don't Exist!!!!!:biglaugh:
     
  8. polymoog

    polymoog TPF Noob!

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    Nice article, thanks for that, have been thinking about trying some HDR at some point :)
     

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