View Full Version : Shapes 3: The Pen Tool as Selection Tool in Corel Painte

09-08-2006, 06:54 PM
Shapes 3: The Shapes Path Tool as Precise Selection Tool in Corel Painter

Painter's Lasso Selection tool is useful for many situations, but there are times when surgical precision is required to select a visual element from an existing composition. In this situation, the Shapes Pen tool is the answer. This installment uses a photographic situation as an example, but the Pen tool is useful for any precise selection job.

Original Source Photographs

This example used here demonstrates how two disparate photographs can be combined to create a strong visual illusion. The composited photo seemingly documents my daughter, Logan, jumping off of the roof of our house! In order to convincingly pull off such a visual stunt, it is crucial to photograph any elements used in the composition with very similar lighting angles and conditions. If this is not observed, the resulting elements will not look consistently lit in the composite image.

I had to do a bit of pre-planning to photograph both Logan and the side of the houser. A day before shooting, I looked at the house and got a sense of the light angle of the midday sun. I then determined that, if Logan was photographed lying down in the driveway in the morning, a similar lighting angle would be achieved. I had her pose as if in a falling attitude, with the sun above her. I photographed the side of the house later in the day.

Pen Tool Outlining

This is really the heart of the installment. The techniques outlined here can be applied to many situations. By default, the Pen tool creates filled Shapes. The Fill and Stroke behavior of the Pen tool is adjusted in the Shapes Tools Property Bar. Select the Pen tool. Disable the Stroke and Fill checkboxes. This allows you to see the underlying content when applying a path.

I find it more precise to magnify an image at least 200%, and often even more. This magnification provides a better sense of the edge of the object being extracted from its background. Photographic imagery is not comprised of crisp edges. It may appear so at normal viewing distances, but the computer enables extreme magnification of the pixels comprising an image. An apparently distinct photographic edge actually transitionally blend from the object to the background the object is positioned against.

I use the soft transitional edge as a guide for creating a Pen tool path. I refer to this activity as walking the edge. Edge-walking does not require Bézier curves with wings and control points. Instead, the path is created with a series of short straight line segments. These segments do need to be fairly close together, otherwise the final layer element may exhibit faceting along the edges. Look at the accomanying illustration to get a sense of point a typical point spacing. As each path anchor point is applied, position it in the middle area of the soft edge. This will prevent the final cut-out layer element from exhibiting color fringing caused by non-subject background contamination.

It is easy to inadvertently create an anchor point that is misplaced either inside or outside of the soft edge. The arrow keys are used to adjust a selected point's position. Each arrow key press moves the anchor point one screen pixel. Hold down the Shift key to move the anchor point ten screen pixels. With a bit of practice, it is easy to reposition an anchor point to the desired location.

Individual existing anchor points can be selected via the Home, End, Page Up, and Page Down keys. The Home key selects the first anchor point in a Shapes path. The End key selects the last anchor point in a Shapes path. The Page Up key sequentially selects adjacent points in the direction of the initial point in the Shapes path. The Page Down key—you guessed it—sequentially selects adjacent points in the direction of the last point in the Shapes path.

When you've made the complete circuit around an element with the Pen tool, click on the initial anchor point to close the Shape. My example doesn't show it, but some elements can have internal holes that must be excised. A hole is made by creating a second Shape within the the larger Shape, then selecting both with the Shapes Selection tool. Select the Make Compound command (Shapes menu). The inner Shape will create a transparent hole within the larger Shape. Only one inner Shape at a time can be compounded with a larger Shape. But an already compounded Shape can be repeatedly compounded as long as it is done with a single Shape.

Path-to-Selection Conversion

Once the desired Shapes path is created, it can be converted into a selection. This is where the power of the Pen path becomes evident. The resulting selection is highly precise. This conversion is accomplished by selecting the Pen path with the Shape Selection tool (as little as a single point can be selected), then either holding down the CTRL(Win)/CMD(Mac) key or right-clicking the mouse to display the Shapes Selection Tool Contextual Menu. Select the Convert To Selection command. The Shape is converted to a selection. Copy and Paste to position the layer element in the desired image.

Motion Blurring the Layer Element

In order to produce a convincing illusion of Logan falling, I employed Painter's Motion Blur filter (Effects > Focus). This filter provides controls for adjusting both the softness (Radius, Thinness) and directionality (Angle) of the blur. The Preserve Transparency checkbox (Layers palette) must be disabled. This allows blurring of both the pixel and visibility mask, producing a motion-blurred edge that blends convincingly with the background.

Adding the Shadow

Without a shadow, Logan just seems to be floating above the photograph. By adding a shadow, she will appear to be a part of the underlying house photograph. To make a shadow, I started by copying the Logan layer (with the Layer Adjuster tool active, hold down the ALT (Win)/OPT(Mac) key and click and drag the layer). With the new duplicate selected, I then enabled Preserve Transparency (Layers palette), sampled (Eyedropper Tool) a shadow color off of the house photograph, and filled (CTRL/CMD + F) the second Logan layer. I changed this layer's Composite Method to Multiply and adjusted the layer's Opacity (Layer palette) to match the existing house shadows.

The Power of the Pen

The Pen tool as precise selection tool is useful in a wide variety of situations. Whenever you are stuck as to how to select a complex image element, consider the Pen tool.

Viva la Painter!

http://img56.imageshack.us/img56/9527/shapes3uh2.th.jpg (http://img56.imageshack.us/my.php?image=shapes3uh2.jpg)