Polygonal Selection Tool: A Thing Of Beauty

polygonal selection toolAdobe Photoshop is the premier photo manipulation software program in the world—it’s so popular “photoshop” has become a verb! Photoshop is the most essential program in Adobe’s Creative Suite, the finest digital software program for image manipulation and retouching. A major function in Photoshop is selecting. Without the selection tools, you cannot choose a particular part of your entire photo in order to change or alter it.

For instance, if you want to change the color of the eyes in a photo portrait, you must select only the eyes. Otherwise, everything in the photo will change. Quite often we want to remove a portion of our image or change the color of an object. In order to do that, you must select it first. Whatever your goal, Photoshop’s powerful selection tools will do the job efficiently and precisely. Take a look at Udemy’s course in Adobe Photoshop CS6: Making Great Selections to get into the power of selections even more. In this tutorial we’re going to cover the polygonal selection tool. We’ll also introduce you to the color picker, the levels window and brush tool. You can learn even more about the fundamentals of Photoshop in Udemy’s Photoshop Essentials course.

Be Selective!

Photoshop’s selection tools are found directly under the move tool, and the polygonal selection tool is found in a dropdown menu off of the tool set with the lasso icon:

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The tool with the hard-edged loop (see below) is the polygonal selection tool. To access it, use your mouse to select it. Then click on the small arrow (located at the bottom right of the icon), to trigger the dropdown menu. Or access the Polygonal Selection Tool via Photoshop shortcut by hitting L and then using SHIFT+L to rotate between the three tools:

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Example 1: Darkening or Lightening A Selected Area

We will use the polygonal selection tool to choose a slightly irregular rectangular feature within the photo, in order to darken or lighten it in Levels. In our example, we will darken a selected area.

Step 1

Find an image with a window or door that is not exactly squared. Open the image by going to File>Open. Search for it, select the image and open it. Be sure to save the image by going to File>Save As. If you go directly to Save, you will save over the original image. Never do that. You always want the original image in case you need to go back to it. So go to File>Save As and give your image a new name, to distinguish it from the original.

Step 2

Choose the polygonal selection tool, as described above, and click once, at one of the corners of the image area you wish to select. (Be sure the image portion that you have selected has all straight sides.) Then click at the next corner, and the next, until you click back on the original corner, completing your selection. You should have an active selection showing, which is often referred to as “the marching ants”—an animated dotted line that indicates the active (chosen) selection:

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Step 3

With the selection made, you will now go to Image>Adjustments>Levels… to reach the Levels Window, where you will make an adjustment to darken the selected area, without altering the surrounding image. The Levels window is where you can adjust the lights, darks and mid-range tones on your entire image, or in a portion of your image.

There are two slider areas. Beneath the large graph area, there is a slider for input levels. Below that is a slider for output levels. We will deal with the input levels slider. Notice the “0” to the left and “255” to the right of the levels slider. By sliding the arrows from the left or right, you affect the overall lightness or darkness of the selected area in your photo. (Note that you can see a portion of your selected area to your left.):

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Step 4

Click on the left-hand slider arrow on the Input Levels slider, and slide it toward the right, until you see the number “43”. Now notice how your selected area in the photo has darkened, while the surrounding, unselected areas of the photo remain the same:

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Step 5

If you are happy with the degree of darkness, click “OK” to exit the levels window. The change we made was very subtle. Here is the change, slightly more exaggerated, to show you the difference between the before and after. Notice that the areas outside the selection have not changed at all. Only the area you selected with the Polygonal Selection Tool has changed:

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Example 2: Altering the Color In A Selected Area

We will use the polygonal selection tool to select the state of New Mexico on a map, changing its color from red to yellow.

Step 1

Before we open the map, let’s choose our color. Go down to the bottom of the tools window and click once on the top paint chip—the foreground color—to open the color picker window. The color we want is yellow—web color #ffcb05. Note that the color is also expressed in CMYK, for print purposes, as shown to the right of the web color box:

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Step 2

Now that you have selected your color, click “OK” to close the color picker window. Notice that the yellow is now in our foreground color swatch. Now open the map that includes New Mexico. If you need to see the state’s lines better, use the zoom tool(Z) to enlarge the map for better viewing. Choose the polygonal selection tool and click once, at any corner of the state. Continue clicking on corners until you have selected them all and have a live selection area. You will see “the marching ants”:

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Step 3

Now select the brush tool (B) to paint the yellow over the red, within the parameters of the selection. Notice that when your brush hits areas outside the selection, no yellow is applied. You have now converted the red within New Mexico’s borders to yellow!

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You now have an introduction to the power and ease of using the polygonal selection tool— how it can be used to select an area with flat sides. Now familiarize yourself with the other two selection tools in the same drop down menu as the polygonal selection tool. The magnetic lasso tool will help you select areas that are unambiguous but irregular, like the silhouette of a person. Use the “regular” lasso tool to draw a selection around a given area, using your mouse or Wacom pen.

The selection tools are everything! Once you get the hang of them and realize how easy they are to work with, you’ll never go back. Udemy offers a huge selection of courses to help you learn all the tools, tricks and techniques available to you in Photoshop. If you are a pro photographer who wants to know all the nuances, don’t wait a moment longer. Check out Udemy’s Photoshop For Professional Photographers. You’ll learn how to get the professional results you want in the shortest time possible. You can also check out some primers on the Udemy blog, such as this basic rundown of using the dodge tool.

If you are a graphic designer, web site developer or digital printmaker, Photoshop has the selection tools to make your photo, design or website project easier. To learn everything you need to know about Photoshop tools, Udemy offers the Photoshop Tools Crash Course. It’s the perfect A-Z guide to Photoshop’s key tools. The course is suitable for everyone, from beginner to advanced, because there is always something new to