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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<title>3.5. Eraser</title>
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<th colspan="3" align="center" id="chaptername">3.5. Eraser</th>
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<td width="20%" align="left"><a accesskey="p" href="ch03s03s04.html">Prev</a> </td>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="gimp-tool-eraser"></a>3.5. Eraser</h3>
</div>
</div>
</div>
<a id="id3323178" class="indexterm"></a>
<div class="informalfigure">
<div class="mediaobject">
<img src="../images/toolbox/toolbox-eraser.png" />
<div class="caption">
<p>
Eraser tool icon in the Toolbox
</p>
</div>
</div>
</div>
<p>
The Eraser is used to remove areas of color from the current layer,
selection, or image. If the Eraser is used on something that does
not support transparency (a channel, a layer mask, or the
Background layer if it lacks an alpha channel), then
erasing will show the background color, as displayed in the Color
Area of the Toolbox. Otherwise, erasing will produce either
partial or full transparency, depending on the settings for the
tool options.
</p>
<p>
If you need to erase some group of pixels completely, leaving no
trace behind of their previous contents, you should check the
"Hard edge" box in the Tool Options. Otherwise, sub-pixel brush
placement will cause partial erasure at the edges of the
brush-stroke, even if you use a hard-edged brush.
</p>
<div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Tip">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Tip]" src="../images/tip.png" />
</td>
<th align="left">Tip</th>
</tr>
<tr>
<td colspan="2" align="left" valign="top">
<p>
If you use GIMP with a tablet, you may find it convenient to
treat the reverse end of the stylus as an eraser. To make this
work, all you need to do is click the reverse end on the Eraser tool
in the Toolbox. Because each end of the stylus is treated as a
separate input device, and each input device has its own
separate tool assignment, the reverse end will then continue to
function as an Eraser as long as you don't select a different
tool with it.
</p>
</td>
</tr>
</table>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3324205"></a>How to Activate</h4>
</div>
</div>
</div>
<p>
The Eraser can be activated from an image menu as
<span class="guimenu">Tools</span>-><span class="guisubmenu">Paint Tools</span>-><span class="guimenuitem">Eraser</span>;
from the Toolbox by clicking on the tool icon
<span class="guiicon">
<span class="inlinemediaobject"><img src="../images/toolbox/eraser.png" /></span>
</span>;
or from the keyboard using the shortcut <span><b class="keycap">E</b></span>.
</p>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3323545"></a>Key modifiers</h4>
</div>
</div>
</div>
<p>
See the <a href="ch03s03.html#gimp-tool-brush" title="3.1. Common Features">Brush Tools
Overview</a> for a description of key modifiers that have the
same effect on all brush tools.
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span><b class="keycap">Ctrl</b></span>:
For the Eraser, holding down the Ctrl key puts it into "color
picker" mode, so that it selects the color of any pixel it is
clicked on. Unlike other brush tools, however, the Eraser sets
the <span class="emphasis"><em>background</em></span> color rather than the
foreground color. This is more useful, because on drawables
that don't support transparency, erasing replaces the erased
areas with the current background color.
</p>
</li>
<li>
<p>
<span><b class="keycap">Alt</b></span>:
For the Eraser, holding down the Alt key switches it into
"anti-erase" mode, as described below in the Tool Options
section. Note that on some systems, the Alt key is trapped
by the Window Manager. If this happens to you, you may be
able to use Shift-Alt instead.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3324476"></a>Tool Options</h4>
</div>
</div>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="../images/note.png" />
</td>
<th align="left">Note</th>
</tr>
<tr>
<td colspan="2" align="left" valign="top">
<p>
See the <a href="ch03s03.html#gimp-tool-brush" title="3.1. Common Features">Brush Tools
Overview</a> for a description of tool options that apply to
many or all brush tools.
</p>
</td>
</tr>
</table>
</div>
<div class="informalfigure">
<div class="mediaobject">
<img src="../images/toolbox/tool-options-eraser.png" />
<div class="caption">
<p>
Tool Options for the Eraser tool
</p>
</div>
</div>
</div>
<p>
See the <a href="ch03s03.html#gimp-tool-brush" title="3.1. Common Features">Brush Tools
Overview</a> for a description of tool options that apply to
many or all brush tools. The Eraser tool has only one special
option (Anti-Erase), but the Opacity control is mentioned here
as well because its name may be a bit confusing.
</p>
<div class="variablelist">
<dl>
<dt>
<span class="term">Opacity</span>
</dt>
<dd>
<p>
The "Opacity" slider, in spite of its name, determines the
"strength" of the tool. Thus, when you erase on a layer
with an alpha channel, the higher the "opacity" you use, the
more transparency you get!
</p>
</dd>
<dt>
<span class="term">Anti Erase</span>
</dt>
<dd>
<p>
The Anti Erase option of the Erase tool can
un-erase areas of an image, even if they are completely
transparent. This feature only works when used on
layers with an alpha channel. In addition to the
checkbutton in the Tool Options, it can also be activated
on-the-fly by holding down the Alt key (or, if the Alt key
is trapped by the Window Manager, by holding down both Shift
and Alt).
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="../images/note.png" />
</td>
<th align="left">Note</th>
</tr>
<tr>
<td colspan="2" align="left" valign="top">
<p>
To understand how anti-erasing is possible, you should
realize that erasing (or cutting, for that matter) only
affects the alpha channel, not the RGB channels that contain
the image data. Even if the result is completely
transparent, the RGB data is still there, you simply can't
see it. Anti-erasing increases the alpha value so that you
can see the RGB data once again.
</p>
</td>
</tr>
</table>
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</dd>
</dl>
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