Tuesday, August 10, 2010
RAW Workflow Basics
Taking full control of your images is easy when you know how to work in RAW
Labels: Image Processing How To
Apply Noise Reduction
The latest cameras do a remarkable job of combating noise, but when the capture requires a high ISO setting some noise is unavoidable. Fortunately, you can counteract noise to some extent in the RAW conversion process. You’ll have options for reducing both luminosity noise (represented by undesirable variations in tonality at the pixel level) and color noise (unwanted color variations). In both cases, you’ll want to use the minimum value that produces an acceptable result. Using an aggressive setting for reducing luminosity noise will reduce detail and perceived sharpness in the image, and excessive color noise reduction can cause colors to blend together or become less vibrant.
While we all want the sharpest images possible, generally it’s best to use a gentle touch when it comes to sharpening in the RAW conversion. Zoom in to a 100% scale for the image, and use just enough sharpening to compensate for a slightly soft appearance. Think of this as the point at which you ensure the image looks like it was captured in perfect focus, and not where you should apply aesthetic sharpening or final sharpening for a print.
Establish Output Settings
Once you’ve optimized the adjustments for your RAW capture, you’re ready to establish your output settings. If your image-editing software supports 16-bit-per-channel images, it’s a good idea to utilize that option for the conversion. Be aware that in many cases, however, 16-bit support is limited. For example, Adobe Photoshop Elements only supports adjustment layers for 8-bit-per-channel images. If your software offers limited (or no) 16-bit support, 8-bit might be your best choice. If a resolution setting is offered, be aware that this is merely a convenience setting and doesn’t impact the actual RAW conversion.
At this point, you’re ready to convert your RAW capture. Mostly, that simply involves choosing the option to open the image based on the settings you’ve applied. You also can save the image directly from most RAW software. In either case, ultimately you want to save the file in a format that enables you to retain the maximum amount of information. The TIFF file format is a safe bet, though you can use a proprietary file format such as the Photoshop PSD file format supported by Photoshop and Elements, as well. A JPEG isn’t the best choice at this point because as you make changes to the image in Photoshop and resave, the effects of the JPEG compression will be cumulative. After a few saves, your once-beautiful RAW file will show significant degradation. With the RAW capture converted, you’re ready to continue applying adjustments in Photoshop, Elements or your other software of choice to fully realize your photographic vision.
Tim Grey has authored over a dozen books on digital photography and imaging for photographers, including the best-selling Photoshop CS4 Workflow. He also publishes the Digital Darkroom Quarterly print newsletter and the Ask Tim Grey eNewsletter. Details are at www.timgrey.com.
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