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HDR (High Dynamic Range): The Future of Photography Jerry Buley, Ph.D. Copyright 2008 by Jerry Buley, All Rights Reserved
Though this article may be brief, it describes one the the biggest changes in photography since it began. Not even the onset of color photography was as big as this change will be. Don't let the brevity the article lead you to think that what it describes is unimportant.
From its beginnings, photography has intended to portray what the eye can see. Yet, no film and no digital sensor existing today can come anywhere close to comprehending the range of lumens from the darkest dark to the brightest light that the eye can see, Though the photographer can see a scene and comprehend it entirely with his eyes, no camera on the market is capable of rendering the entire breadth of lumens in that scene It is impossible for the photographer to accurately capture a high contrast scene in a single frame. If she/he exposes for the dark portion, the bright portions become overexposed. If she/he exposes for the bright portions, details are lost in the darkest portions of the picture. High Dynamic Range (HDR), though in its relative infancy, promises to overcome this stark limitation. Using it, the photographer creates two or more frames that are pixel for pixel identical except for the length of the exposure. The intent is to capture a broader range of lumens so as to, better approximate the broad range of lumens the eye can see. Using specialized software, the photographer than blends the multiple exposures to create a single image that contains much more detail than any single frame from the same camera can portray. The following four thumbnails are an example of this blending. The top three pictures are a set of bracketed exposures. 0, -1, and +1 f/stop. The fourth picture is the HDR blended picture that resulted from blending the three images in a software program called Dynamic-Photo HDR. (Click on a thumbnail to see a larger version.) The image is of the Point Restaurant one foggy morning* on the Malecon in Puerto Penasco, Mexico.
Currently, HDR is best suited for landscapes and other scenes in which there is no movement, and even then requires the camera be mounted on a tripod. Movement of the camera between exposures makes blending the multiple exposures difficult. Yet, in the future we will want to take HDR pictures of people and other things that move. The pressure will be on camera makers to develop technologies that incorporate HDR. We can envision a camera that in the same instant will take three or more photographs of the same scene using internal software that will keep the images identical (except for exposure) so that a tripod is not required, and so that HDR images of people and moving objects will be possible. HDR will change photography more than any prior innovation in the field including the invention of color film and the invention of the digital sensor. Contained in this article are several HDR pictures (taken in Sedona, Arizona, and in Puerto Penasco, Mexico) each based on three exposures. Depending on the amount of contrast in the scene, one exposure was 1-2 stops above optimum exposure. The second was 1-2 stops below. The last exposure was optimal for the scene. Every point in an HDR picture can be perfectly exposed with immense detail and vibrant color We are not yet used to seeing pictures like this, though as they occur more and more frequently they will replace what a pictures should "normally" look like. Right now, HDR pictures look somehow "foreign." Think about it. All photography before this has been based on film and sensors that are incapable of representing the range of lumens the eye can see. When the range of lumens is increased significantly, the resulting picture will look different. HDR photographs are strangely beautiful, nevertheless. As the technology becomes more prevalent, they will begin to look less strange..
HDR: Late Afternoon in Sedona, Arizona |
