Rectangle Select
Rectangle selection and ellipse selection tools
The rectangle selection tool and the ellipse selection tool can be found at the top-left of the toolbox. Actually you may not find them very useful for working with photographs, because not many photographs are made up of rectangular or oval shapes. Even if you take a photograph of a rectangular wall, it will only appear as a rectangle in the photo if the axis of the lens is perpendicular to the wall.
To use the rectangle or ellipse selection tools, just click the one you want (or simply press R or E on the keyboard) and then drag on the picture to create the rectangular or elliptical selection area. To select a square or circle, hold down the Shift key while you use the respective tools. The edges of the selection will be indicated with a shimmering effect called 'marching ants'.
Let's use this photo (left) of a beautiful hula dancer in Hawaii to practice with the ellipse tool. We'll put a soft-edged selection ellipse around her, then invert the selection so that everything outside the ellipse is selected, then we will clear the selection which will cause the cleared area to be replaced with the background color (yellow). As a final step we will crop the image, giving something like the second image (without the word 'sample' of course).
Before you use the ellipse selection tool, turn on feathering and set the feathering radius to 50 pixels so that our manipulation of the photo will not be too obvious. Now select the dancer. Once the selection is made, try dragging any point inside the selection - notice that the selection ellipse moves and so do its contents. Undo the move and try Alt+dragging any point inside the selection (hold down the Alt key and drag) - now you can reposition the ellipse without moving its contents. When the selection looks good then invert the selection with Select>Invert so that the edges of the picture are selected. We are about to clear the selected area and replace it with the background color but before we do so you should go to the toolbox and set the background color to yellow. Now clear the selected area with Edit>Clear or Ctrl+K. Finally, use the cropping tool to crop the picture.
Don't you agree that the 'vignette' effect concentrates attention on that pretty smile? (It's the kind of smile she would only give to someone she really liked the look of, don't you agree?)