The main selection tools are easy to use. The more complicated paths tool is not described here.
To determine whether a new selection should replace, be added to, be subtracted from, or intersect with an existing selection, use the Mode row in the tool options.
Rectangle Select
This tool can be used to select rectangular or square areas. To select an area with a fixed aspect ratio, width, height or size, activate the Fixed option and choose the relevant mode in the Tool Options dialog. To create a square, hold Shift while selecting a region.
Ellipse Select
Use this to select elliptical or circular areas. The same options are available as with the rectangular selection. To create a circle, hold Shift while selecting a region.
Free Select (Lasso)
With this tool, you can create a selection based on a combination of freehand drawing and polygonal segments. To draw a freehand line, drag the mouse over the image with the left mouse button pressed. To create a polygonal segment, release the mouse button where the segment should start and press it again where the segment should end. To complete the selection, hover the pointer above the starting point and click inside the circle.
Fuzzy Select (Magic Wand)
This tool selects a continuous region based on color similarities. Set the maximum difference between colors in the tool options dialog in Threshold. By default, the selection is based only on the active layer. To base the selection on all visible layers, check Sample merged.
Select by Color
With this tool, select all the pixels in the image with the same or a similar color as the clicked pixel. The maximum difference between colors can be set in the tool options dialog in Threshold. The important difference between this tool and Fuzzy Select is that Fuzzy Select works on continuous color areas while Select by Color selects all pixels with similar colors in the whole image regardless of their position.
Scissors
Click a series of points in the image. As you click, the points are connected based on color differences. Click the first point to close the area. Convert it to a regular selection by clicking inside it.
Foreground Selection
The Foreground Selection tool lets you semi-automatically select an object in a photograph with minimal manual effort.
To use the Foreground Selection tool, follow these steps:
Activate the Foreground Selection tool by clicking its icon in the Toolbox or choosing Tools › Selection Tools › Foreground Select from the menu.
Roughly select the foreground object you want to extract. Select as little as possible from the background but include the whole object. At this point, the tool works like the Fuzzy Select tool.
When you release the mouse button, the deselected part of the image is covered with a dark blue mask.
Draw a continuous line through the foreground object going over colors which will be kept for the extraction. Do not paint over background pixels.
When you release the mouse button, the entire background is covered with a dark blue mask. If parts of the object are also masked, paint over them. The mask will adapt.
When you are satisfied with the mask, press Enter. The mask will be converted to a new selection.