Example Select by Color Tool

The Mode function in this dialog offers the following options:

• Replace the current selection: Creating a new selection on the image deletes an existing selection and creates a new one.

• Add to the current selection: You can use the tool, or similar tools, consecutively to add to an existing selection. (Note that the Mode > Add to the current selection option must be selected prior to using the tool.) The newly selected image areas will be grouped as a single selection.

• Subtract from the current selection: This option allows the selected tool to deduct an area from an existing selection.

• Intersect with the current selection: If a selection exists, you can use this option to create a new selection that will be automatically intersected with the existing selection; the result is a new selection, covering the area the two given selections had in common.

Additional options, specific to the Fuzzy Select tool, are listed here:

• Antialiasing: This option removes the aliasing or step effect (i.e., sharp "steps" at the border of a selection that result from cutting with a mask without feathering). It spreads pixels at the border from opaque toward transparent, creating an integral, natural look when copying and pasting objects. Without anti-aliasing, a copied element will look like it was cut by scissors and slapped on the image.

• Feather edges: This option creates a "soft border" for the selection. Feather edges is not the default setting, so you'll want to change the settings before editing if you want feathered edges. If you click the check box at Feather edges, a slider titled Radius shows up. Move the Radius slider to set the feathering width. A value between 2 px and 5 px should be sufficient, depending on the desired effect and image resolution.

• Select transparent areas: Allows the Fuzzy Select tool to select completely transparent areas like a color. If the option is not checked, transparent areas cannot be selected. The possibility to select transparent areas is rather helpful. For instance, to trace the contours of an image object on an otherwise transparent layer, it's often easier to select the transparent area and invert the selection than to select the object itself.

• Sample merged: This option ensures that all visible image areas on all layers are included when the selection by color is calculated. If this option is not checked, the tool will only select the desired color on the active, single layer.

• Threshold: This option determines the range of similar colors that will be selected. The higher the threshold, the wider the range of colors.

• Select by: This option offers a drop-down menu. Composite is the default setting; it actually calculates a selection of the color values of the pixel chosen with the tool by clicking on it. The other menu options let you choose which component of the image the program should use to calculate the image. The components you can choose from are the three fundamental colors (red, green, and blue), hue, saturation, and value.

Proceed as follows:

• Remove small defects from the sky, if you find any. Select these spots in the sky (or selection islands with an animated border) by circling them with the Free Select tool (Lasso) while either holding the Shift key down or selecting Mode > Add to current selection from the tool's settings dialog box.

• Remember that you can use the Zoom tool to magnify an image area.

• When your selection is cleared of "islands" (or spots), increase the selection size by approximately 4 px using the Select > Grow menu item. Then choose Select > Feather to add feathering to the selection border (approximately 5 px). The horizon and the contour of the trees will now be feathered. After deleting the area of the blurred sky, the remaining landscape contour will look natural, and the scissors effect will be avoided. Otherwise, you can do this by using the Feather edges option of the Fuzzy Select tool.

To complete the following steps and to delete the sky, so that the cleared area will be transparent, you must assign an alpha channel to the layer. Select Add Alpha Channel in the context menu by right-clicking the Landscape layer in the Layers dialog.

Select the Edit > Clear menu item to delete the sky on the Landscape layer. Select the Select > Save to Channel menu item to save your selection as an alpha channel before deleting it in the image by choosing Select > None.

Figure 3.26

Extended selection with feathered border

Figure 3.26

Extended selection with feathered border

Figure 3.27

The Landscape layer with deleted sky (transparent area)

Figure 3.27

The Landscape layer with deleted sky (transparent area)

Take a closer look at the image: Since the border of the selection was feathered, the contour of the image that remains is feathered toward transparency. The transition is smooth and natural looking.

In the following exercises, you will use GIMP tools to select colors and fill layers or selections with a color. These will be described in more detail in the following sections. Briefly, you will do the following:

• Use the Color Picker from the Toolbox to select a light-blue shade as the foreground color.

• Make the Sky layer your active layer.

• Select the Bucket Fill tool from the Toolbox and click on the image. The Sky layer will be filled entirely with the selected foreground color.

• If your entire image turned blue, it happened because the Sky layer is on top of the stack. Move the layer underneath the landscape by clicking the Lower Layer button in the Layers dialog.

• You can use the Dodge/Burn tool to darken the mountains in the background. Set the Burn control in the tool's options. Set Opacity


to a lower value (about 20%), then select or create a big (about 200 pixels in diameter) brush pointer with soft edge. This will allow you to edit the area smoothly and avoid abrupt dark patches. You can also lighten up the overly dark meadow areas in the foreground by selecting the Dodge tool. You can use the same brush pointer and opacity to touch up the mountains if you so desire. Otherwise, for darkening the mountains, you may select the mountains by color with the Fuzzy Select tool and perform a tonality correction on them (Colors > Levels). Use feathering for the selection (Select > Feather).

Digital Cameras For Beginners

Digital Cameras For Beginners

Although we usually tend to think of the digital camera as the best thing since sliced bread, there are both pros and cons with its use. Nothing is available on the market that does not have both a good and a bad side, but the key is to weigh the good against the bad in order to come up with the best of both worlds.

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