Thursday, June 28, 2007
Masking Essentials I
Mastering the art of the mask will empower you to control your images with precision
The ability to work in specific areas of an image with unparalleled precision and repeatable results, along with the ability to combine multiple exposures seamlessly and flexibly, are two key advances that are propelling the current revolution in photographic practice. Still, selection and masking are topics that plague many longtime Photoshop users. This whirlwind tour will demystify the process and set you well on your way to mastering these essential skills.
At its most basic, masking can be extremely simple—black hides, white reveals and shades of gray provide a variety of opacities. That said, getting the precise shades of gray in exactly the right places can be taxing.
There are times when you have to make a mask by hand. (Styluses, like those made by Wacom, are great aids in making selections by hand; their pressure sensitivity is particularly useful for changing brush characteristics, such as size, in midstroke.) Making and refining masks by hand takes time, so think twice before you do. Make an initial investment of time to determine the most efficient and precise route to accomplish a task before you begin; you'll be repaid with countless dividends.
There are a number of key concepts and strategies that make selection and masking more efficient and precise.
Start With A Good Foundation
A selection is often the foundation of a mask. Starting with the right Selection tool will speed you along your way and make the task easier. Often, the contours these methods define are more precise than those defined manually; from time to time, hands shake. Even if these strategies don't define an area as precisely as you'd like, they can get the process of selection started, performing a majority of the work, which you can then refine manually.
• Use the Magic Wand tool or Magnetic Lasso tool to select easy-to-define areas containing significant contrast in brightness or hue.
• Use the Select > Color Range feature to target specific hues separately from one another.
• Use a luminance selection (the foundation for a contrast mask) to target highlights or shadows. To target highlights, drag a channel to the Load Channel As Selection icon in the Channels palette and add a layer mask (Layer > Add A Layer Mask). To target shadows, drag a channel to the Load Channel As Selection icon in the Channels palette and inverse the selection (Select > Inverse) before adding the layer mask. (Alternately, invert the layer mask.)
• If significant contrast exists between the area to be selected and its surroundings, a contour mask (outline) can be derived from a contrast mask by driving shades of gray to black and white using Curves.
Using an adjustment layer, you can temporarily increase contrast or saturation in an image to make selecting an area much easier. After the selection is made, you can discard the adjustment layer.