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Thursday, June 28, 2007

Masking Essentials I

Mastering the art of the mask will empower you to control your images with precision

Filter It

A mask is a grayscale image. You can do anything to a mask that you can do to a grayscale image, including filter it. Use the filters Maximum and Minimum (Filter > Other > Maximum or Minimum) to reposition a contour mask. Maximum expands white, while Minimum contracts it. (These filters do to masks what Expand and Contract do to selections.)

Soften a contour mask if it's jagged or too hard by blurring it (Filter > Blur > Gaussian Blur). This is more precise than feathering a selection because instead of guessing at numbers, you can see the affect as you preview the filter.

Blurring a mask can also smooth uneven transitions within a mask, often caused when multiple strokes of a brush set to a low opacity overlap. You can create gradients with complex contours or non-uniform transitions by starting with a brush and then using high-blur settings. Blurring introduces shades of gray, which can be very useful.

Adjust It

If a mask contains shades of gray, you can darken, lighten or adjust the contrast of a mask by applying Curves directly to the mask. Darkening decreases opacity; lightening increases opacity. Move the black point up to make black gray, increasing opacity. Move the white point down to make white gray, decreasing opacity. Move the black point to the white point and vice versa to invert the mask. Move the midpoint to control the placement of a midpoint in a gradient. Increase the contrast in a mask, and a long, smooth transition will become shorter and more abrupt; increase it dramatically, and you can turn a smooth transition into a hard line. If a contour contains shades of gray, you can reposition it this way, much like the filters Maximum and Minimum but with even greater precision. Move the black point to the right to contract a mask; move the white point to the left to expand a mask. If a mask doesn't contain shades of gray, you can introduce them by blurring it.

Here are a few helpful mnemonic devices to remember when masking an image:

1 Black conceals, white reveals.

2 A selection selects not only what is selected but also everything else. (It can be inversed.)

3 Always get the image to do the work for you. (It's more efficient and precise.)

4 You never have to define the same contour twice. (It's better not to, as it's highly unlikely you'll define it the same way twice.)

Let me leave you with a parting thought. Start rough, refine later. Start with a rough selection to make sure the adjustment you intend to make to an image will work to your satisfaction before you refine the accompanying mask.




Too many times, a great deal of time is spent making a perfect mask for an imperfect adjustment that ultimately never gets used. Refining selections and masks takes time, even with all of these helpful techniques. There's nothing more precious than your time. Make sure the task is worth your commitment.



Author of Adobe Photoshop Master Class, John Paul Caponigro is an internationally acclaimed fine artist. A Canon Explorer of Light and an Epson Stylus Pro, he's a passionate teacher who offers an array of workshops in his studio throughout the year. See a live demonstration of this material at the currently touring Epson Print Academy. To learn more techniques, visit www.johnpaulcaponigro.com and receive a free subscription to his e-news Insights.