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By Root 1875 0

to refine the edge boundaries. This essentially analyzes the border edges in the image and calculates the most appropriate mask opacities to use, primarily according to the Radius setting you have applied. What you want to do here is to adjust the Radius setting to what is most appropriate for the type of image you are masking. If the edges to be masked are mostly fine sharp edges, then a low Radius setting will work best. For example, a Radius of 1 pixel would be suitable for a selection that contained a lot of fine edges such as a wire fence. If the edges you wish to mask are soft and fuzzy, then a wider Radius setting will be most appropriate and it is suggested that you should aim to set the Radius here as wide as you can get away with.

Since a photographic image is most likely going to contain a mixture of sharp and soft edges, this is where the refine radius brush ( ) comes in. This can be used to extend the areas of the edge to be refined. So if you have chosen a narrow Radius setting, which would be appropriate for refining narrow edges, you can paint with the above brush with a wider brush diameter to paint over the softer edges, and thereby apply the most suitable edge refinement algorithm along those sections of the border edge. In use, you select the brush and adjust the cursor size, using the square bracket keys ( ) to determine what size brush you need to work with. Once you have done this you can click and drag to paint along the edges to be refined (see Figure 9.26). Bear in mind here that after each brush stroke, Photoshop needs to recalculate a new edge outline using the new Truer Edge algorithm and this may take a few seconds to complete, during which time you won't be able to edit the edge any further. It may seem a little off-putting at first, but I assure you that the time delay you may experience here is nothing compared with the amount of time you are able to save through the use of this automated masking process. Holding down the key switches from the refine radius brush to the erase refinement tool ( ). Or, you can select this tool from the same tool menu as the refine radius brush, or use the key to toggle between these two tool modes. This tool can be used to remove areas of the edge to be refined and basically undoes the refined radius mask editing. When working in the Reveal Layers mode, the refine radius painting shows as a green overlay and the erase refinement tool painting shows up as a red overlay (see Figures 9.26 and 9.27).

Figure 9.26 You need a narrow thickness edge to refine sharp mask edges and a wider thickness to refine soft, wide mask edges. Here you can see the refine radius brush used at different thicknesses to manually edit a mask. You can set a narrow or wide Radius in the Refine Edge dialog and use the refine radius brush to modify that edge.

Figure 9.27 This shows the erase refinement tool in use, which shows up as a red overlay when applied in the Reveal Layer mode.

The Smart Radius option can often help improve the mask edge appearance, as it automatically adjusts the radius for the hard and soft edges found in the border transition area. With hair selections in particular, you should find it helps if you aim to set the Radius slider as high as you can and check the ‘Smart Radius’ option. I have found that this combination usually produces the best hair mask.

Adjust Edge section

In the Adjust Edge section there are four sliders. The Smooth slider is designed to smooth out jagged selection edges but without rounding off the corners. The Feather slider uniformly softens the edges of the selection and produces a soft-edged transition between the selection area and the surrounding pixels, while the Contrast slider can be used to make soft edges crisper and remove artifacts along the edges of a selection, which are typically caused when using a high Radius setting. When compositing photographic elements you usually you want the edges of a mask to maintain a certain degree of softness, so you don't necessarily want to apply too much contrast to a mask here. Some