Over the last few articles, I have discussed basic selection techniques using both the marquee and lasso tools. While these tools are helpful, wouldn't it be nice if quality selections could be created with a single click? With the magic wand, they can. Of course, understanding how the magic wand's settings will affect the final selection is the key to good results. This month I will provide an overview of the tips and tricks to mastering the magic wand.

Located in the right hand column of the tool bar (second from the top), the magic wand can be a photographer's best friend. The concept behind the magic wand is simple. Click on any part of the image, and all of the pixels that are similar to that point will be selected. By similar, I am referring to similarity in tonal value. Click on a blue sky and similar shades of blue are selected while green and red tones are not.

The flexibility of the magic wand comes into play with the controls in the option menu (located above the image). For our purposes, only three controls matter: anti-alias, tolerance, and contiguous. Anti-alias is the simplest: always leave it checked. Un-checking anti-alias results in jagged edged selections that are not worth making.

The primary control for the magic wand is the tolerance setting. Earlier, I indicated that the magic wand selects tones that are similar. This brings up the obvious question of how do we define similar? The tolerance setting allows me define how similar pixels must be to be included in the selection. A setting of "0" will only select pixels that are identical to the pixel I click. As the tolerance increases, a broader range of tones will be included in a selection. For example, a setting of "15" might select part of the clear blue sky while "30" will select the entire sky. A value of "100" will select everything, including the blue sky, the fall colored trees, and the mountain they grow on.

Playing with the tolerance it is possible to find the best setting for a particular image. Based on experience, I find that a value of "30" works as a good starting point. With a single click, I can determine the quality of my selection. If too little is selected, increasing the tolerance will increase the tones that are included. Too large a selection can be reduced by lowering the tolerance to a more appropriate level.

After tolerance is set, the choice of whether or not to use contiguous must be made. Checking contiguous results in similar pixels directly adjacent to the click-point to be selected. Similar tones that are not directly adjacent will not be selected. In contrast, un-checking contiguous will select all similar tones within the image, regardless of where they are located. In effect, un-checking contiguous lets the selection process jump over dissimilar tones to reach similar ones.

To clarify the difference, let's look at two examples. In the image of fall color, changing the contiguous setting before clicking on the blue sky produces different selections. Checking the contiguous box and using a tolerance value of "30" results in a good selection of the major portion of the blue sky. The problem, however, is that the small patches of blue sky that can be seen between the leaves are not included in the selection. Golden colored leaves (different tones) separate the selected blue sky from the smaller patches of blue sky (similar tones). The result is that only part of the sky is selected. In contrast, un-checking contiguous selects both the large segment of blue sky and the smaller pieces that occur between the leaves because similar tones within the image are selected regardless of their location. In this case, the better selection is created by un-checking contiguous so that the entire blue sky is selected.

The second example involves an image of a meadowlark perched on barbed wire. The background is a uniform tone which lends itself to selection by the magic wand. Before going on, try to imaging how the contiguous setting will affect the final selection. Checking contiguous (tolerance of "30") creates a good selection of the background around the bird, but fails to include everything. Specifically, the background under the barbed wire and between the bird's legs is not included. Using these settings, the magic wand is not able to "jump over" the legs or barbed wire to include the entire background. Un-checking contiguous (tolerance of "30") appears to be an ideal solution. Unfortunately, a new problem appears when this is done. While the entire background is included in the new selection, portions of the bird are also included. The similar tones in the meadowlark and the background result in a very poor selection. So, how do we get a good selection of the entire background area? In this case, check contiguous and create the basic selection (the upper portion of the background). Next, hold down "Shift" and add to the current selection by clicking on the background between the bird's legs and under the barbed wire. In this way, a good selection (all background and no bird) can be completed with only three clicks.

While the magic wand can be used on any image, it works best with images that contain uniform tonal areas. The traditional "bird on a stick" photography style containing a sharp subject against a background of solid color is an ideal situation for the magic wand. For best results, however, remember that it is often easier to select what you don't want rather then the area you want. In the meadowlark example, it is much easier to select the background then the bird. If selecting the bird is my goal, it is much easier to select the background and then inverse the selection (Select → Inverse) then to try selecting the bird directly. Similar methods can be used to select subjects against a blue sky. Use the magic wand tool to select the sky and then use inverse to select everything else.

In closing, let me provide a final tip about touching up magic wand selections. When a selection is created, it is not uncommon for some degree of touching up to be needed. Small areas of the desires area remain outside of the selection. When the missing pieces are large, or small in number, it is best to either adjust the tolerance setting or hold down "Shift" and add to the current selection. When the points are numerous, or tiny, it is usually easier to switch tools and perform the cleanup with a different selection tool. Personally, I use the magic wand for my basic selection and then I switch to the free hand lasso tool to perform small scale touch ups. Enlarging the image, I alternate between "Shift" (add to current selection) and "Alt" (Subtract from current selection) to fine tune my selection. This combination of tools provides an excellent way to create accurate selections.

Chris Gamel has been an active wildlife photographer for the past 14 years. The combination of his biological research and photographic interests has taken him around the world. In 2001, Chris discovered the joys of digital photography and he hasn't looked back. Chris lives with his wife and daughter in Salt Lake City where he teaches courses at Weber State University and Salt Lake Community College. To see more of Chris's photography, visit his web site at www.Animal-Antics.net.

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