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<ul class="navigation"><li class="prev"><a accesskey="p" class="prev" href="WSfd1234e1c4b69f30ea53e41001031ab64-76c3a.html" title="Saving selections and using masks"><img src="images/blank.gif" alt="Previous" width="17" height="17" /></a></li><li class="next"><a accesskey="n" class="next" href="WSfd1234e1c4b69f30ea53e41001031ab64-76c1a.html" title="Create a temporary quick mask"><img src="images/blank.gif" alt="Next" width="17" height="17" /></a></li></ul><div class="hierarchy" id="hierarchy"><a href="WSfd1234e1c4b69f30ea53e41001031ab64-7701a.html">Selecting and masking</a> /
     <a href="WSfd1234e1c4b69f30ea53e41001031ab64-76c3a.html"><b>Saving selections and using masks</b></a> 
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                <h1>
                    About masks and alpha channels
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                <div><p>When
you select part of an image, the area that is not selected is “masked”,
or protected from editing. So, when you create a mask, you isolate
and protect areas of an image as you apply color changes, filters,
or other effects to the rest of the image. You can also use masks
for complex image editing such as gradually applying color or filter
effects to an image. </p>
<div class="fignone"><img alt="" id="se_13" src="images/se_13.png" /><div class="figdesc">Examples of masks </div><br /><dl><dt class="dlterm">A.</dt>
<dd>Opaque mask used to protect the background and edit
the butterfly</dd><p class="dlseparator"></p><dt class="dlterm">B.</dt>
<dd>Opaque mask used to protect
the butterfly and color the background</dd><p class="dlseparator"></p><dt class="dlterm">C.</dt>
<dd>Semitransparent
mask used to color the background and part of the butterfly</dd><p class="dlseparator"></p></dl>
</div><p>Masks are stored in alpha channels. Masks and channels are grayscale
images, so you can edit them like any other image with painting
tools, editing tools and filters. Areas painted black on a mask
are protected, and areas painted white are editable. </p>
<p>Use Quick Mask mode to convert a selection to a temporary mask
for easier editing. The Quick Mask appears as a colored overlay
with adjustable opacity. You can edit the Quick Mask using any painting
tool or modify it with a filter. Once you exit Quick Mask mode the
mask is converted back to a selection on the image.</p>
<p>To save a selection more permanently, you can store it as an
alpha channel. The alpha channel stores the selection as an editable
grayscale mask in the Channels panel. Once stored as an alpha channel,
you can reload the selection at any time or even load it into another
image.</p>
<div class="fignone"><img alt="" id="se_14" src="images/se_14.png" /><div class="figdesc">Selection saved as an alpha channel in Channels panel</div><br /></div><div class="note"><span class="notetitle">Note:  </span>You can mask or hide parts of a layer using
a layer mask.</div>
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