Colton Writes HDR Article
Posted on Thursday, July 18, 2013
Colleges' Chief Photographer Kevin Colton recently authored and illustrated an article for the Journal of the University Photographers' Association of America. An instructional guide on the use of High Dynamic Range Photography (HDR), the article discusses the evolution of the technology and provides step-by-step examples for getting the most out of it.
"When HDR programs first came around, the images had a very surreal look to them. But today's technology allows a layered photograph to be created without the surreal look of the older programs," explains Colton.
He starts by guiding the reader from the point of taking images. "One important factor to remember is that when creating images for HDR you only change the shutter speed and not the aperture. You must keep the depth of field the same for all images so that they align together in the final stacked image."
Colton then goes on to explain how to use software programs designed for HDR.
Recently, Colton won a number of awards for his photography, including for HDR image, "Boathouse at Sunrise," which won a Gold award in the "Digital or Computer Enhanced Images" category of the Council for Advancement and Support of Education District II 2012 Accolades Awards Program.
The full article is below. To view it with the accompanying illustrations, visit the Journal online.
Journal of the University Photographers' Association of America
HDR High Dynamic Range Photography
Instruction and Photos by Kevin Colton • Hobart and William Smith Colleges • Spring 2013
In 2004 when I was first introduced to the HDR image, Photomatix software was the number one program used by most photographers. Now nine years later Photomatix Pro by HDRSoft is still the leading program used by HDR enthusiasts. What is HDR? The Wikipedia definition is "High Dynamic Range Imaging (HDRI or HDR) is a set of methods used in imaging and photography to allow a greater dynamic range between the lightest and darkest areas of an image than current standard digital imaging methods or photographic methods." For me, it means being able to create an image the way I saw it when the set of photos were taken. When HDR programs first came around the images had a very surreal look to them. But today's technology allows a layered photograph to be created without the surreal look of the older programs.
Let's take five images and run them through Photomatix Pro 2. The images (fig. 1) were captured with a -2, -1, 0, +1,+2 exposure. One important factor to remember is that when creating images for HDR you only change the shutter speed and not the aperture. You must keep the depth of field the same for all images so that they align together in the final stacked image. Opening Photomatix Pro brings you to a pop-up window titled "Workflow shortcuts" (fig. 2), click the top button to load the five bracketed photos you have chosen. You may browse for the images or simply drag them from the finder window and even from programs such as PhotoMechanic. Photomatix Pro will allow you to use either raw images or JPEG images for the selected photos. I always try to shoot landscapes in raw and keep as much file information within the photos as possible. As you can see in figure 2, I also have checked the show intermediary 32-bit HDR Image box. Although most monitors cannot show you the entire color range of 32-bit, I like to keep as much information as I can attached to the selected images.
Now that we have all five images in the selected bracketed photos window, you drop to the bottom right and click "OK." "The Preprocessing Option" (fig. 3) window will open. This set of adjustments allows you to prepare the images for merging. First on the list is "Align source images." Most landscape type images will align best by selecting the option of horizontal and vertical shifts. Check this box and select the top option. Next you will see the remove ghost check box. Checking this box allows the program to look for details within the images that might have moved when taking the set of exposures.
Objects such as blowing leaves, people walking, moving cars, you get the idea. Within the photos I have chosen the only thing that moved quickly would be the ocean waves. The moving waves in the finished image would not bother me so I chose the "automatic" option with high detection. The third option is to reduce noise. As you can see I have checked this box and have chosen to reduce noise on the under exposed images only. Although an HDR image seems to have a tendency to be noisier than a layered image, usually the only images to reduce noise in are the underexposed ones if you shoot in RAW. The final check box will help reduce the chromatic aberrations. I choose to do most of my adjustments preprocess rather than in post processing with Photoshop or Lightroom.
And the last setting you can set your white balance for RAW images and adjust the entire set. Most always I have done this while creating the image and use the As Shot option.
Now we're ready to see what our image will begin to look like. Press the "Preprocess" button at the bottom and Photomatix will stack and align the images to become one that will be our tone mapped image. The new window (fig. 4) that opens will have an adjustment panel, preview window with the image and a host of presets. An important setting to remember is at the bottom of the adjustment panel. Be sure that the reset and preset both show the default option. Photomatix Pro gives you two options for processing your image, Tone Mapping and Exposure Fusion. For this demonstration, I have chosen "tone mapping." By using the preview image as a guide, choose a style from the presets to the right as a starting point. After choosing a preset, you can adjust the image by the controls in the settings window. Once you have the image in preview the way you like it, it's time to process the changes. Click "Process" at the bottom of the adjustment panel to allow the program to apply the changes to the image. Once you have processed the image, you will have a chance to apply finishing touches to contrast, sharpening and saturation by using the pop-up palette before saving the image. The next step is to save the image. I recommend saving the image as a TIFF 16-bit if you plan to do any further processing.
Photomatix allows you to save the image as a TIFF 8-bit or JPEG if you so desire.
That's all there is to it - you can now open your image in Photoshop or Lightroom and do any small tweaks for a finished HDR photo (fig. 5) that should look very close to what you saw when you captured it. The Photomatix website has a great tutorial and user manual that will guide you through the image process. You can find these and a lot of other useful information at www.hdrsoft.com.