What is it?
The Refine Edge command, introduced in Photoshop CS3 gave users a set of tools for improving the quality of selection edges and adding a visual preview to a set of useful, if obscure commands in the Select menu. In Photoshop CS4, Adobe took the commands from Refine Edge and added them to the newly created Masks panel giving you control over the edges of masks instead of selections. Refine Mask helps you clean up the edges of masks to eliminate the color contamination along edges, often called edge spill, or smooth out ragged selections from tools like Magic Wand or Color Range.
Why is it important?
The differences between a beginner’s layer masks and a master retoucher are found in the edges of the mask. The beginner’s edges appear as visible seams between layers. The master’s masks have no visible seams and layers blend naturally without interruption. Achieving a Master’s edge often meant a lot of time and elbow-grease manually smoothing the edges of a mask. Now, with the Refine Mask command you can control the feather, contrast and smoothness of an edge. All tools that will help you attain master-level results in a minimal amount of time.
To jump start your apprenticeship, young Grasshopper, here’s a quick summary of the Refine Mask’s features:
– Radius: Used to “tease” out fine detail along mask edges and force the mask to match the contours of the masked object. A high radius setting will make the edge of the mask exceedingly soft and “gray.” Remedy this with the Contrast Slider.
– Contrast: Used in conjunction with the Radius slider to create realistic masks along difficult edges. As the Radius slider is increased, the mask edge becomes very wide and diffuse. Adding Contrast helps to reclaim the integrity of the edge to make a viable mask.
– Smooth: Eliminates the rough and jagged portions of a selection edge often found in selections made with the Magic Wand or Color Range tool. Generally, you’ll want to use as high of a Smooth setting as possible, but be careful, high Smooth settings tend to round corners and eliminate points.
– Feather: Blurs the edges of the mask slightly to make the transition between layers less visible. I recommend feathering your mask to match the sharpness of focus. If your subject is sharply focussed, you’ll want to use a very low radius. If the subject is softly focused, say with a shallow depth of field, a higher Feather setting is needed to create a natural-looking transition.
– Contract/Expand: The best way to remove color contamination along the edge of a selection is to contract the selection slightly, eliminating the offending pixels. Be sure you’re zoomed into 100% to preview the edge of the mask to protect against excessively contracting the edge of the mask.
Bonus Tip: Preview Modes: Cycle through the five preview modes at the bottom of the Refine Mask dialog by pressing “F”. These mode are, from left to right; Standard selection border (marching ants), Quick Mask (red overlay), Black Background (useful for light objects), White Background (the litmus test for cutouts), and Mask mode, ideal for seeing the effect of the feather. I tend to jump back and forth between the black and white backgrounds since these give the most critical assessment of edge quality.