MacDirectory Magazine

Winter-Spring 2009 (#40)

MacDirectory magazine is the premiere creative lifestyle magazine for Apple enthusiasts featuring interviews, in-depth tech reviews, Apple news, insights, latest Apple patents, apps, market analysis, entertainment and more.

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Page 113 of 179

112 MacDirectory REVIEW | CREATIVITY PHOTOSHOP CS4 > A GREAT TOOL FOR HIGH DYNAMIC RANGE IMAGING Sometimes it takes more than one photograph to create that perfect image. High dynamic range imaging (HDR or HDRI) has increasingly been used to improve the apparent dynamic range of digital photographs, or make the photo look closer to what you see. And Photoshop CS4 offers detailed tools to create high dynamic range photos. What is HDR? HDR is a process for combining several images taken at different exposures into a single image that accurately represent the wide light intensity range perceived by the human eye. The intent of HDR is to accurately represent the wide range of light and shadows found in real scenes and captured in digital photos. For example, if you take a picture of a scene in bright sunlight (with the exposure based on bright areas) the shadows may not have any detail. Take the same picture exposed to capture details in the shadows, and the highlights will be over exposed. Your camera sensor is capable of only capturing a certain dynamic range (the difference between bright and dark areas). Expensive cameras have a wider dynamic range than lesser expensive cameras. Nikon's D3, a professional single lens reflex (SLR) camera, has a dynamic range of approximately 12.2, whereas Nikon's top-of-the-line point and shoot camera, the Coolpix 6000, has a dynamic range of 10.2 (based on testing by DxO Labs . Less expensive digital SLR cameras will have smaller dynamic ranges. In comparison to all these cameras, your eye has a wide dynamic range of about 24. With current technology, even the most expensive camera will not have the visual dynamic range of the human eye. How does a photographer overcome their equipment limitations? One option is to pick scenes where the dynamic range is less than the camera's sensors. A second option is to take several images at different exposures and apply the high dynamic range tools provided in Adobe Photoshop CS4. Photoshop CS4 includes a "Merge to HDR" tool [File > Automate > Merge to HDR]. This feature permits the user to select several photos, which can be combined into an HDR image. After selecting this tool, a dialog window opens for the user to select the source files for the HDR image. Once the source images are selected, click "OK". Photoshop CS4 will automatically align the selected images and then process these images in to a 32- bit HDR preview image. The preview window permits the user to make some picture adjustments before final processing. Click "OK" and the HDR image is displayed in Photoshop CS4. A second option is using a combination of two layer tools: Auto-Align Layers and Auto-Blend Layers. To apply these features, first create a Photoshop document where each photo that you want to combine is a layer in the document. Unless the photos were taken on a tripod, you will want to first apply the Auto-Align Layers [Edit > Auto-Align Layers]. This tool aligns the layers based on the content in each layer, and is a great tool for still images. However, as expected, don't select slightly moving objects as your subject, like floating boats or moving trees in the wind, since the images won't align perfectly. Next, select the Auto-Blend Layers [Edit > Auto-Blend Layers] tool and a dialog window is displayed. In this window select the Stack Images Blend Method followed by clicking on Seamless Tones and Colors. Click "OK" and Photoshop will blend the layers based on the image content. Further image adjustments may be made using the entire set of tools. Both options allow greater enhancement of your photograph, however the second method offers greater creative control over individual elements. Photoshop CS4 offers more than just pixel enhancing tools for great digital photography. Product Photoshop CS4 Made by Adobe Price $699, Upgrade $199 Pros Powerful tool to develop high dynamic imagery Cons Requires experience in advanced photography and Photoshop Rating HHHH WORDS BY LISA P. HILL PHOTO 1 PHOTO 2 FINAL PHOTO

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