What Constitutes an HDR Image?

I’m often asked what is HDR photography? HDR simply stated means High Dynamic Range. The impetus behind HDR is to reveal detail in all ranges of the exposure. It drives me crazy when people say that the only way to create HDR is by combining multiple images. Digital sensors are capable of a much broader exposure latitude than film; they can record so much information that was unavailable with film allowing us to create a broad range of tonality from light to dark within a single frame.

To my way of thinking HDR means being able to bring out detail in both shadow and highlight areas in a photo. Granted there are times, a strong backlight or a subject in deep shadow, when the exposure range is so great that combining a range of exposures is the only way to attain that goal but as long as the histogram/exposure is within the range of the sensor there is enough information in a single frame to create HDR. It is not any different that dodging and burning when you boil it down.

I remember my “ah-ha” moment in the darkroom eons ago when I had a negative that was severely underexposed in the shadows and my instructor explained that through dodging and burning I could extract the info that was there and create the image I thought I had taken. I was expanding the dynamic range beyond what a single exposure would produce, going straight from the negative through the enlarger, simply by burning in the underexposed shadows while dodging the overexposed highlights to tone map the image. Isn’t that the essence of Ansel Adams’ zone system? He exposed for as broad a range of tones as his film would record and then completed the image in the darkroom dodging and burning areas of the image to produce an image that had the full range of tones from pure black through pure white.

When folks refer to an image today as HDR I think what they are actually referring to is the stylization of the image. The emphasis is on enhancing not only the range of exposure but also enhancement of the saturation, hues and tints within the image along with increased contrast and sharpening. Sometimes the only way to accomplish those goals is through combining multiple exposures but simply combining multiple exposures usually results in a very flat image with very little contrast. It doesn’t become what is commonly referred to as an “HDR” until it has been tone mapped which, to my way of thinking, menas stylized through processing to attain the photographer’s vision for the photo. Taking this a step further I would argue that a single frame can be tone mapped and stylized to create what is referred to today as HDR photography.

19 thoughts on “What Constitutes an HDR Image?

  1. Great post as always, Nick. What drives me crazy is the thought that HDR is the latest snd greatest, unlesss you consider 60+ year old technology the latest! The first example of HDR I have found if the cover photograph on Life Magazine’s February 27, 1950 issue of an atomic blast on Bikini Island.

    As I have shared with you before, I am a fan of extending the dynamic range of a photograph to more nearly capture all of the detail that can be seen by the naked eye. To me, HDR, or EDR (Extended Dynamic Range) as I prefer to call it has its place. I use single- or multiple-image (as many as 7) depending on wht I see in the subject.

    Keep up the great work, my friend.


  2. Greetings from a fellow rider (’05 Gold Wing) and professional photographer who started in this industry at age 6 doing darkroom work (well… learning as an apprentice) in my dad’s photography business. I’ve been at it now for 54 years and teach HDR workshops throughout the Western States. I have five books behind me (my photography illustrating them) and am now working on a project of love: Two Weeks On The Mother Road (Route 66 for those too young to remember how the road received its name). Nick, I am covering the entire road (California to Chicago since I moved from Chicago (thankfully) in 1986) from the saddle of my 2005, 35th Anniversary, Honda Gold Wing (just put a heated Russell Saddle on in August).

    Into the fray…

    Nick, your thoughts and comments are accurate on 99.9% of the points; slightly off on one, just one – which is a purely technical issue. Yet, is is an important one. Lauren will also discover why her comment about seeing and HDR image in Life’s 2/27/1950 image is incorrect – from a very important, and purely technical, aspect.

    Why do I make my bold statement? First of all, HDR imaging as a technique is developed in an MIT mathematics lab for the film industry in 1982 – every book on HDR imaging I have researched (more than 50 of them), as well as a few of the journal articles published in the scientific literature, bear this out. Lauren, what you see in the Life issue of 2/27/50 is a well-woked, properly exposed, 4X5 negative processed in the darkroom using Ansel Adam’s Zone System (the premier darkroom and exposure technique then as well as now). By the way, did you know when you have your internal light meters set for the full scene on the digital cameras of today the camera’s computer automatically uses the Zone System as its exposure guide?

    Nick, you are particularly correct in your statement concerning what we see today as being stylistic. This is the result of the tone-mapping (the darkroom processing) and any Photoshop (or other application) used after the tone-mapping procedure to finalize the print. No question about it – a lot, and I mean a LOT of people overuse the tone-mapping and post processing to give the final, tone-mapped image, the cartoonish, over-the-top, often surrealistic look we have often come to recognize (many hate) as an HDR image.

    Yes, HDR does stand for High Dynamic Range; However, HDR is NOT the final output – the final output is actually an LDR image (Low Dynamic Range) comparable to transparency film of the analog years. (An HDR file [.rad; .hdr] is 32 bit while a tif, dng, psd file is at most 16 bit and more typically 8-bit. JPG files and other variations such as PNG are typically 8-bit image files. This does not change the look of the output from an HDR image capture; it only makes the image printable on today’s printers (home and lab).

    I saw a comment in an article (I do not remember the journal at this time – I think it was Outdoor Photographer – as it has been a few months) saying the images we see in print and which utilized HDR imaging capture technique were more High Definition than HDR. This is close to what Lauren calls her EDR output, and not a bad description at all, Lauren.

    Technically, a single frame capture is NOT an HDR image. It may very well be a tone-mapped image if you ran it through a camera raw processor such as Photomatix Pro 4 (or another application similar) and tone-mapped the image to pull out the shadows, tone down the blown out highs, etc.

    It is physically, and mathematically, impossible to have an HDR capture in today’s DSLRs (or the new 4/3 or micro 4/3 cameras) without a multi-frame capture which captures the full 23 Exposure Values the human eye sees. The best camera on the market for Dynamic Range used to be the Fuji S5Pro. Top end Nikon, Canon, Sigma, Sony, and others, DSLRs of today capture about 12 to 15 Exposure values at BEST. The medium format cameras do no better.

    To be accurate within the industry, and amongst ourselves, it is important to keep the terminology, and the science, of the craft accurate. Thusly, unless you are physically taking a multi-frame capture of a scene – you do NOT, technically, have an HDR image.


    Richard S Hockett, MBA, DTM
    SunRidge Photo

    1. Thanks for your comments. I rode the Mother Road, Route 66, from Chicago to Santa Monica in 2001 on my Softail Standard. I then headed up the coast to San Francisco and from there on to Laramie, Wyoming. The last leg of the trip was home from Laramie to Louisville. It was the first time I had ever taken a long trip by motorcycle. I was on the road for nearly a month, traveled over 7000 miles and learned that I absolutely loved long distance riding. Best of all; I made friends on that initial cross country ride that I still ride with to this day.

      Since then I’ve been on sections of Route 66 more times than I can recall. One of my favorite towns along the route is Tucumcari, New Mexico which boasts lots of neon and vintage motels. Enjoy the trip it will stay with you for the rest of your life.

      I googled your name searching for your books but didn’t find them. I’d like to read them; I’m sure there are insights for me in them. Where can I find them?

  3. There are probably more opinions on HDR photography than their are HDR photographers and HDR photography viewiers combined. It’ like an old joke that went something like “if you want 3 opinions ask 2 economists”. Here’s my input:

    When I succeed in HDR, you won’t even know, or suspect, that it is HDR. It is also almost fair to say that I tone map every image I print. As good as our image sensors are, the new Nikon D800E has 14.5 EV, they will never be as good as our eyes, and in any event our print media are not as good as either. So how do I fit a full range to my print? In digital, I shoot for the highlights and process for the shadows. I was trained in the Zone System for film and I still use a Zone System with digital. Black is black, white is white, but even coal has shadow detail and there is highlight detail in the snow. But B&W or color, tonal transitions should be smooth and natural, tones and colors should be clean and detail should be everywhere it is important. I emphasize, detail should be everywhere it is important. Detail should not be everywhere. When viewing a print, our mind accepts that certain areas will be too dark or too light for detail. It is when we force detail into these areas that the effect becomes unnatural. My concern for HDR photography would be that people come to expect that HDR, by its nature, must look a certain way. The term that I use to describe this HDR effect is “painterly”.

    At the moment of capture, every image I capture is incomplete. What I have at this moment is, in essence, the negative. The image will not be complete until I have processed and printed that image. Remember, Ansel Adams wrote 3 books, “The Camera”, The Negative”, and “The Print. Adams also believed that photography was a process beginning with a previsualization of the final print prior to exposure. When we grasp the potential, and the limitations, of our various hardware, software and media we can realize some beautiful prints. Or as Ansel Adams also said, “there is nothing worse than a sharp image of a fuzzy concept.”

    1. Thank you Daniel for this comment. I agree with your premise that we strive for HDR whenever we conceive an image and process it to that end.I agree with your statement about the importance of detail; the end goal is not that every blade of grass is rendered rather that the essence of the grass is there just as it is when we view it with our eyes. We cannot see every leaf on a tree without deconstructing the tree and observing each leaf separately yet our eyes and our brain can combine the essence of the tree and “know” the detail that exists.

  4. Thank you Daniel for adding to the discussion. This the kind of dialoge I hoped to foster with my post.The more we share with one another the more rounded we all become. Thanks again for commenting.

  5. A camera’s RAW file *can contain* more information in color and brightness than a conventional monitor or printer can reproduce or use, so I use “tonemapping” as a way to extract more of the information I want and put inside an 8-bit per channel image (which most monitors and some printers can reproduce). I use Adobe Lightroom and Photomatix to accomplish this process…

    An “HDR” Image (by the definition of some of the “technical” books on the subject) has no requirements other than file format. The range of brightness the file can contain can be nearly anything, but is limited by the file format and its storage methods (not the capture or processing). I use Photomatix which *expects* a certain minimum range of brightness information to function correctly in multiple images, so the vendor warns about using a single RAW or a 16-bit image as input (but do not prevent it).

    Outside the vernacular of scientists (and my vocation of engineering), many photographers have an expectation that a *true* HDR Image is made from multiple exposures of a camera because that is all they have heard (care?) about – and assume having a large range of brightness to preserve and work with is really *the only reason to use* any of the HDR file formats available (Like 56kbs to 320kbs example).

    Again, the file formats are “HDR” Images – not the content. The content is what makes the file format either useful or just excessive overhead. You could bracket 9 exposures (using shutter speed) of a dull grey wall and combine them to make an “HDR” – but you’ll have nothing more than a merged image of a dull grey wall. Common sense dictates much of this…

    As for “tonemapping”, that is the act (art?) of compressing visual detail regarding brightness and color from some input to a more limited output. Film photographers call this the “response curve” of their film. Printers call this “print color coordination” or “gamut correction.” Your eyes call this “rhodopsin reactions coupled with iris response, lens clarity and rod fatigue.” In other words, the requirements to be HDRI (High Dynamic Range Imaging) are not as specific as many *experts* present.

    To further confuse the matter “tone compressors” are considered tonemappers in computer graphics, just that they are “global operators” (using the same criteria and methods for all pixels equally) as opposed to “local operators” (which vary the compression based on each pixel and its neighbors’ brightness and color) which are sometimes called “detail enhancers” (or many other names). There are literally hundreds of tonemapping algorithms out there in computer graphics – Photomatix provides three (and their first one is not for 32-bit input).

    Ultimately, do what you want, use different methods. Your results will vary, but that’s what makes “experimental” digital photography fun!! Whatever floats YOUR boat…

  6. I agree that HDR is not limited to the combining of multiple images. By getting the entire range of light that my camera has captured, I am more easily able to develop my photos and significantly reduce the time to do so from what it used to take for me to dodge and burn in the lab with wet film. I have found that many of my photographs of landscape in Afghanistan initially appear almost greyed out due to weather conditions and dust. That said, developing them to bring out the contrasts, sharpness, hues, tones and saturation give me the same result as I can get by combining multiple exposures across the breadth of stops from one end to the other. At the same time, it doesn’t require a high end software package to develop these images. I completely enjoy the images I capture with my 14MP Lumix as much as those I capture with my Canons. The quality of the camera lens, the capability of the chip to capture the broad range, and the capability of the photographer to bring out the range from the saved image makes all the difference. A cheap camera in the hands of a good photographer will produce incredible images.

  7. I love the picture and enjoyed reading the the comments. One important point regarding Ansel Adams and the Zone System. To correctly use this concept you carefully use a spotmeter (there was a special model calculated in Zones) to measure the exposure in the shadow area where some detail must be held. Then the middle tones and then the highlights. Calculating how many F/stops apart (zones) between the shadows and the hightones are then determined. If there are 9 stops (zones) the negative would receive N (normal) development. If more than 9, the development time was shortened a calculated amount: this is called N-. If there were less than 9 zones then the developing time was expanded: N+.
    Even with this kind of precision the printing would often require dodging and burning and frequently some bleaching. Of course this wonderful system works well with a camera that uses sheet film. In the case of 35mm or 120, the entire roll had to be developed for only 1 exposure/develop calculation. This is a simplification of the Zone System which is completely discussed in Adam’s book “The Negative”.

  8. LOL. I am a newbie to this HDR Photography site and got here through LinkedIn. I work for a large, international engineering company, called, you guessed it…HDR. Thus I joined thinking it was a gathering of amateur photographers, working at HDR, who share photography tips. Lucky me…turns out it is a great group for photography information!

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