Adobe Photoshop CS5 for Photographers - Martin Evening [118]
Figure 4.1 This shows a comparison between a raw image processed in Camera Raw 5.0 (top) and Camera Raw 6.0 (bottom) and the inset images show 400% close-up views. This is also available as a layered image on the DVD.
Ideal noise reduction
The thing to understand here is that the ideal noise reduction in the demosaic process isn't where every trace of noise gets removed from the image. OK, so you might think this would be a good thing to achieve, but you would in fact end up with a photograph where in close-up the image detail would look rather plastic and over-smooth in appearance. What the Camera Raw engineers determined was this: it is better to concentrate on eradicating the noise we generally find obtrusive, such as color and luminance pattern noise (which is usually a problem with high ISO capture), but preserve the residual luminance noise that is random in nature. The result of this precise filtering are images that are as free as possible of ugly artifacts, yet retain a fine-grain-like structure that photographers might be tempted to describe as being ‘film-like’.
The next component is the new revised sharpening. Sharpening is achieved by adding halos to the edges in an image. Generally speaking, halos add a light halo on one side of an edge and a dark halo on the other. To quote Camera Raw engineer Eric Chan (who worked on the new Camera Raw sharpening), ‘good sharpening consists of halos that everybody sees, but nobody notices.’ To this end, the halo edges in Camera Raw have been made more subtle and rebalanced such that the darker edges are a little less dark and the brighter edges are brighter. They are still there of course but you are less likely to actually ‘see’ them as visible halos in an image. You should only notice them in the way they create the illusion of sharpness. The Radius sharpening has also been improved. When you select a Sharpen Radius that's within the 0.5–1.0 range the halos are now made narrower. Previously, the halos were still quite thick at these low radius settings and it should now be possible to sharpen fine-detailed subjects more effectively. You'll also read later about how the Detail panel Sharpen settings are linked to the Sharpen mode of the adjustment tools. This means you can use the adjustment brush or Gradient filter as creative sharpening tools to ‘dial in’ more (or less) sharpness. Lastly, we have the new, improved noise reduction controls which offer more options than before for removing the luminance and color noise from a photograph.
Sample sharpening image
To help explain how the Camera Raw sharpening tools work, I have prepared a sample test image that you can access from the DVD. The Figure 4.2 image has been especially designed to highlight the way the various slider controls work when viewed at 100%. Although this is a TIFF image, it's one where the image has been left unsharpened and the lessons you learn here can equally be applied to sharpening raw photos.
Figure 4.2 The sample image that's used on the following pages can be found on the DVD. To open this photo via Camera Raw, use Bridge to locate the test image and use File Open in Camera Raw, or use the keyboard shortcut.
Detail panel
To sharpen an image in Camera Raw, I suggest you start off by going to Bridge, browse to select a photo and choose File Open in Camera Raw, or use the keyboard shortcut. The Sharpening controls are all located in the Detail panel in the Camera Raw dialog (Figure 4.3). If the photo won't open via Camera Raw, check you have enabled TIFF images to open