12

ABOUT THE IMAGE

Ancient & Rusty Dodge

Canon EOS 1v, 28-70mm at 28mm f/2.8, f/16.0 @ 1/100, Kodak Supra 100, 2400 x 1608 pixel 11.6MB .tif, scanned with Polaroid Sprint-Scan 4000 and VueScan

Nearly all digital images need to be sharpened — period. Well, I better qualify that somewhat. Those images that you intend to be sharp — need to be sharpened as soft edges are just one of the characteristics of digitized photos no matter whether they have been created with a scanner or with a digital camera.

The rusty Dodge photo shown in Figure 12.1 was chosen for this technique because most sharpening techniques suffer from a tradeoff between sharper edges (on edges that ought to be sharpened) and getting undesirable effects, such as enhanced grain, halos, excessively pronounced textures, and other unwanted effects. This rusty Dodge image has a variety of edges, plus lots of different kinds of textures that are useful for learning about the Unsharp Mask filter, the key tool for making images look sharper.

While this technique isn't particularly exciting, it is an essential one to make your photos look as good as they can. For this reason in this technique you learn three different approaches to sharpening images, and you get more information on the hows and whys than any other technique in the book. The three different approaches that are covered are:

■ Using Unsharp Mask on the entire image

■ Sharpening only one or two channels instead of the entire image

■ Using filters to select only the edges, and then sharpen only the edges

I should point out that the best way to get sharp images is to use a high-quality scanner to scan a sharp negative, slide, or photo or to shoot a sharp image with a high-quality digital camera — then you usually still need to sharpen the image digitally. Although it would be nice, I am sad to report you have no way to sharpen an out-of-focus digital photo. In fact, when using the following sharpening techniques, you'll quickly realize that we are not really sharpening them. Instead, we are creating the illusion that they are sharp by digitally emphasizing edges in the image by making one side of an edge lighter and the other side darker.

As you soon discover, the illusion effect we use to make an image appear sharp is resolution dependent. This means that you should not apply sharpening effects to an image until you know what your final output will be. A sharpened high-resolution image won't have the optimal amount of sharpening if it is down-sized to be used as a low-resolution image on a Web page or vice-versa. Consequently, sharpening ought to be one of the last steps in your workflow. One other reason to leave sharpening as one of the last steps in your workflow is because the sharpening effect will likely be removed or damaged, if you first sharpen your image and then use a variety of other commands and filters.

USING UNSHARP MASK ON THE ENTIRE IMAGE

STEP 1: OPEN FILE

■ File ^ Open (Ctrl+O) to display the Open dialog box.Double-click the \12folder to open it and then click the dodge-before.tif file to select it. Click Open to open the file.

A few minor adjustments have already been made to this image using Levels to enhance the image so that this technique can be devoted to sharpening — a most important topic for photographers.

STEP 2: DUPLICATE LAYER

Before taking any steps to sharpen an image, first duplicate the layer. Not only does this duplicate layer make it easy for you to switch between before sharpening and after sharpening images so that you can view the differences, but it also allows the option of painting back in some of the original image, or using a mask or selection to limit what is or isn't sharpened. Additionally, you can blend the background layer with the sharpened layer by using one or more of the blend modes to further improve the sharpness of the image.

JOHN BROWNLOW

Besides being an excellent photogra-pher,John Brownlow is a significant contributor and discussion leader of useful Internet-based content on a variety of

JOHN BROWNLOW

Besides being an excellent photogra-pher,John Brownlow is a significant contributor and discussion leader of useful Internet-based content on a variety of important photographic and imaging topics.He is the founder and moderator of the highly active and useful Street Photography (650+ members), Digital Silver (850+ members), and Big Neg

■ Choose Layer >- Duplicate Layer to get the Duplicate Layer dialog box. Type sharpened in the As box and then click OK.

0 0

Post a comment