Fuzzy Select
Fuzzy Select tool
Take a look at the photo below (taken at the Luxor Casino, Las Vegas USA). Because the photo contains so much sky, the camera has underexposed the statue, which looks almost like a silhouette. We could increase the brightness of the entire picture (preferably using the level control or the curves control) but this would lighten the sky which might then become a boring uniform white (try it if you like). Therefore we would like to lighten the statue without affecting the sky - a perfect case for using a selection.
One of the easiest selection tools to use is the Fuzzy Select tool as shown at left (called the magic wand tool in some programs). This tool selects contiguous areas that have roughly the same color. Check out the options that are available for this tool. The threshold (called tolerance in some programs) controls how wide a range of colors the tool will select (if the number is small the tool will select only areas that have almost exactly the same color as the point clicked). Anti-aliasing ensures that the edge of the selection will be smooth, not jagged, and this should usually be turned on. You may be assuming that we will be clicking on the statue with this tool in order to try to select it but it is actually better to try to select the sky for the sky has a very even color and is therefore very easy to select with this tool. Once the sky is selected it will be easy to inverse the selection so that everything but the sky is selected.
First set the threshold to a small value such as 10 and try clicking the sky - you will probably find that only a small part of the sky is selected (the edges of the selected area are marked by shimmering 'marching ants'). Then deselect with Shift+Ctrl+A or Select>None, set the threshold to a high value such as 150 (the maximum is 255) and click the sky again. Note that you can adjust the level either by dragging or by selecting the number and typing in a new number (don't forget to press Enter). Now you will probably find that in addition to the sky a part of the statue is also selected. Deselect again, set the threshold to an intermediate value such as 80 and click the sky once more. Now you will probably be pleased by the result, except that only half the sky is selected because the light area is broken by the statue. To add to the existing selection, hold down the Shift key while you click the other half of the sky (notice the small + sign next to the pointer). Alternatively you could click the corresponding icon in the tool's option dialog:
This option is less good because you must remember to switch back to the normal 'replace' mode when you've finished adding to the selection. Actually, if you look closely, you'll see there are a couple of other areas that may need to be added to your sky selection, between the branches of the palm tree.
Select-by-Color tool
To be honest, you could have selected all these areas simultaneously using the Select-by-Color Tool instead of the Fuzzy Select tool:
The difference between the two tools is that the Fuzzy Select tool selects contiguous areas with similar colors while the select-by-color tool selects all parts of the image that have similar colors, whether contiguous or not.
Once all the sky is selected you can invert the selection with Select>Invert (Ctrl+I). Now only the statue and the palm tree are selected. Experiment with the curve control (Colors>Curves...) or the level control (Colors>Levels...) to lighten the statue, without overdoing it. Notice how, when you adjust the settings, only the selected area is affected, not the sky. You may also want to make the colors a little more intense by choosing Colors>Hue-Saturation and then using the saturation slider (the saturation of the colors is a measure of how intense they are). Save your work when you are finished.
We will return to the same image in the 'layers' lesson and I will show you how to completely replace the sky with a new one!