Enhancing Microcontrast Using DOP Detail Extractor
Adapted from Photographic Multishot Techniques (Rocky Nook)
Uwe Steinmueller, co-author and occasional lead author of many Rocky Nook books, is well-known through his Outbackphoto web site. He is also the creator of the DOP Detail Extractor Photoshop plugin (DOP stands for “Digital Outback Photo”, the name of Uwe Steinmueller‘s company)—a tool for enhancing microcontrast. Once installed, the plugin is made available under File > Scripts.
Unlike the other filters we’ve worked with, Detail Extractor doesn’t require you to create a duplicate layer manually—the plugin automatically creates one and gives it a name which describes exactly the settings used for the layer in question. This new layer also appears automatically in the Layers palette. By default, Detail Extractor sets blending mode to Luminosity, in order to prevent image saturation from being affected by the process.
The plug-in’s individual parameter settings function as follows:
Detail Size controls the pixel radius within which differences in contrast should be accentuated. You should set this value according to your subject, image resolution, and the size of your planned display format. Higher image resolution will require a slightly higher Detail Size value. The default value is 15 for images with a resolution of 8–12 megapixels. Smaller values will result in softer images, which can be an advantage for images with finely structured transitions (as long as you are not working with additional layer masks).
Boost is best described as a kind of “strength” setting, and should be used sparingly (usually with values between zero and 15). Any value above 50 will produce grunging-type effects. (There is an example of this type of effect later in the article.) Extra Detail strengthens local contrast enhancement, especially in shadow areas.
Protect sets the degree to which shadows and highlights will be protec ted from being clipped. The default value is 50 – lower values increase detail contrast, but can lead to blocked-out shadows and washed-out highlights. Values above 50 protect shadows and highlights but can reduce highlight and shadow microcontrast.
Detail+ increases the detail enhancement, and has a similar effect to additional sharpening.
Clipping- Activating this option limits the dynamic range to between 10 and 245 (referring to the RGB luminance scale of 0–255). The image will no longer include any absolute white or black pixels, and will appear to have slightly less contrast when viewed on a monitor. This effect helps in printing situations, as dark areas (with values below 10) usually block out, and it is generally not possible to differentiate visually between tonal values above 245 and virgin white paper (255) anyway.
The filter’s default settings produce low-key but recognizable effects. In most images, the differences remain subtle.
Once you have found settings which work for your type of image and suit your personal style, you can save them by clicking Save, and recall them through the Settings menu. This is important, because Detail Extractor doesn‘t have a preview mode. It is only possible to make judgments about the effects of your settings once they have been applied to your image. Detail Extractor does, however, save the settings that are active at shutdown, and loads these automatically when the plug-in is restarted.
Remember to give your settings profiles names that describe precisely the settings you used. Older profiles that you no longer require can be deleted by selecting them (Settings) and clicking Delete. The illustration below shows our initial image, which has already been slightly retouched and optimized. Although the blacks and the slight shimmer of oil contrast well with the dark red wheels, and although the steam escaping from the valve gives the image an air of authenticity, we still think our image could bear a little enhancement using Detail Extractor.
We set the Detail Size value to 17 pixels. This parameter should be set based on the resolution of your image—images with higher resolutions will sometimes need a higher value. For our image, we used a solid Boost factor of 57, which is close to the upper limit of values that can be usefully applied to normal images. Anything more would bring us into grunge territory, which is simply not suitable for use with this subject.
We set Extra Detail to its maximum justifiable limit of 30, which is why we also set Protect to 63 in order to prevent the highlights already present in the image from washing out, and the shadows from blocking. Because we were processing this image for use with the offset printing process used for the book from which this article is taken, we also activated the Clipping option to reduce the overall dynamic range, thus preserving shadow and highlight detail at the print stage.
Increasing microcontrast would have further accentuated some of the detail visible behind the locomotive, so we deliberately blurred those areas in advance using Photoshop’s Gaussian blur filter (Filters > Gaussian Blur) and a layer mask. Enhancing microcontrast without this initial background softening made some of the brighter details in the image overbearing and distracting.
The illustration below shows an enlarged detail before and after Detail Extractor was applied. The processed version has a much more three-dimensional look and a crisp flair.
The term “grunging” is derived from the “grunge” rock music style. In the world of digital photography, it is used to describe an effect which sharpens tonal values in an image to a point where contrast is highly exaggerated and the entire image begins to look “super-real” and generally over-the-top. Detail Extractor can be effectively used to create this kind of effect by setting the base parameters to extremely high values. If a single application doesn’t achieve the effect you are looking for, you can simply run your already-filtered image through the filter again. We have found that more than three consecutive runs produce results that are no longer usable.
Grunging is a specialized image effect which isn’t suitable for all subjects or image types. Occasionally, however, it can turn a normal image into a real eye-catcher. Here is an example.
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Excerpted from Photographic Multishot Techniques by Juergen Gulbins and Rainer Gulbins (Rocky Nook). Copyright © 2009 Rocky Nook. All rights reserved. Used with permission