Tuesday, December 23, 2008
XDR, Part V
Using Photomatix to enhance your extended dynamic range images
Light Smoothing is one of the strongest effects. In large part it determines the quality of the tone mapping, specifically with respect to haloing, providing either realistic or exaggerated results. After Strength, start here and determine which of the five fixed settings generates the appearance you desire. Use higher settings for more naturalistic appearances (less compression of dynamic range and less haloing). Use lower settings for more aggressive tone mapping (more compression of dynamic range and haloing).
Luminosity & Gamma
Luminosity and Gamma both adjust overall brightness. Luminosity increases contrast as it lightens more than Gamma. You can use both in combination with one another to adjust midtone contrast by moving them in opposite directions.
Micro-Contrast & Micro-Smoothing
Micro-contrast and micro-smoothing adjust very fine detail—edges, texture and noise. Micro-contrast provides edge sharpening (with reduced haloing) and texture accentuation. Micro-smoothing reduces noise, often accentuated with higher micro-contrast settings. Both can generate naturalistic or exaggerated effects. Use them to find the balance between contouring and smoothing you desire. Photomatix provides the necessary 100% preview as a magnifying glass icon that lets you examine small areas of your image, but not larger areas, requiring you to scan through an image before committing to a final effect.
Reducing dynamic range/contrast often reduces saturation. With HDR imagery, this reduction of saturation can be global (use Saturation to control it) or regionally targeted to shadows and highlights (use Saturation Shadows and Saturation Highlights). You can use Photomatix’s sliders to generate naturalistic or exaggerated effects. For naturalistic effects, carefully examine relative saturation relationships.
Photomatix offers impressive controls over essential image elements affected by HDR merges. Chief among these are control over halos, micro-contrast accentuation, micro-smoothing and control of saturation in highlights and shadows (areas that tend to need aggressive tone mapping).
It’s unlikely that the results you get from Photomatix won’t need additional postprocessing in Photoshop, such as increased midtone contrast, localized adjustment, retouching and sharpening, but without starting with Photomatix, many HDR images generated solely with Photoshop would be either unappealing and in some cases impossible to achieve. You may not need the full power of Photomatix for every HDR merge, but then again, you may become so enamored of it that you won’t want to use anything else.
With a little care and attention, the effect you produce with these tools can be one of your choosing. If used aggressively, you can produce a contemporary HDR effect that can give your images a new look. If used conservatively, you can produce a classic effect that’s virtually unnoticeable. Whether conservatively or aggressively applied, HDR imagery challenges many of the fundamental notions of what photographs can do and what they look like. As our understanding of this constantly evolves with advances in technology and contemporary taste, it pays to explore these options and see what potential they hold for the advancement of your image-making process and personal vision.
John Paul Caponigro is an internationally respected fine artist, author of Adobe Photoshop Master Class and the DVD series R/Evolution, and a member of the Photoshop Hall of Fame. Read more of his column R/Evolution online at digital photopro.com. Get more than 100 free downloads and his free enews Insights at www.johnpaulcaponigro.com.
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