1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>3.9. Convolve (Blur/Sharpen)</title>
<link rel="stylesheet" href="gimp-help-plain.css" type="text/css" />
<link rel="stylesheet" href="gimp-help-screen.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.66.1" />
<link rel="start" href="index.html" title=" " />
<link rel="up" href="ch03s03.html" title="3. Brush Tools" />
<link rel="prev" href="ch03s03s08.html" title="3.8. Clone Tool" />
<link rel="next" href="ch03s03s10.html" title="3.10. Dodge or Burn" />
</head>
<body>
<div xmlns="" class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center" id="chaptername">3.9. Convolve (Blur/Sharpen)</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="ch03s03s08.html">Prev</a> </td>
<th width="60%" align="center" id="sectionname">3.9. Convolve (Blur/Sharpen)</th>
<td width="20%" align="right"> <a accesskey="n" href="ch03s03s10.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="gimp-tool-convolve"></a>3.9. Convolve (Blur/Sharpen)</h3>
</div>
</div>
</div>
<a id="id3324732" class="indexterm"></a>
<div class="informalfigure">
<div class="mediaobject">
<img src="../images/toolbox/toolbox-blur.png" />
<div class="caption">
<p>
Convolve tool icon in the Toolbox
</p>
</div>
</div>
</div>
<p>
The Convolve tool uses the current brush to locally blur or
sharpen your image. Blurring with it can be useful if some element
of your image stands out too much, and you would like to soften
it. If you want to blur a whole layer, or a large part of one,
you will probably be better off using one of the <a href="ch06s02.html" title="2. Blur filters">Blur Filters</a>. The direction of a
brushstroke has no effect: if you want directional blurring, use
the Smudge tool.
</p>
<p>
In "Sharpen" mode, the tool works by increasing the contrast where
the brush is applied. A little bit of this may be useful, but
overapplication will produce noise. Some of the <a href="ch06s06.html" title="6. Enhance filters">Enhancement Filters</a>, particularly
the <a href="ch06s06s07.html" title="6.7. Unsharp Mask">Unsharp Mask</a>, do a
much cleaner job of sharpening areas of a layer.
</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>
You can create a more sophisticated sharpening brush using the
Clone tool. To do this, start by duplicating the layer you want
to work on, and run a sharpening filter, such as Unsharp Mask,
on the copy. Then activate the Clone tool, and in its Tool
Options set Source to "Image source" and Alignment to
"Registered". Set the Opacity to a modest value, such as 10.
Then Ctrl-click on the copy to make it the source image. If you
now paint on the original layer, you will mix together, where
the brush is applied, the sharpened version with the unsharpened
version.
</p>
</td>
</tr>
</table>
</div>
<p>
Both blurring and sharpening work incrementally: moving the brush
repeatedly over an area will increase the effect with each
additional pass. The Rate control allows you to determine how
quickly the modifications accumulate. The Opacity control,
however, can be used to limit the amount of blurring that can be
produced by a single brushstroke, regardless of how many passes
are made with it.
</p>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3325558"></a>How to Activate</h4>
</div>
</div>
</div>
<p>
The Convolve tool can be activated from an image menu as
<span class="guimenu">Tools</span>-><span class="guisubmenu">Paint Tools</span>-><span class="guimenuitem">Convolve</span>;
from the Toolbox by clicking on the tool icon
<span class="guiicon">
<span class="inlinemediaobject"><img src="../images/toolbox/blur.png" /></span>
</span>;
or from the keyboard using the shortcut <span><b class="keycap">V</b></span>.
</p>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3326100"></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>:
Holding down the Ctrl key toggles between Blur and Sharpen
modes; it reverses the setting shown in the Tool Options.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3326148"></a>Tool Options</h4>
</div>
</div>
</div>
<div class="informalfigure">
<div class="mediaobject">
<img src="../images/toolbox/tool-options-convolve.png" />
<div class="caption">
<p>
Tool Options for the Convolve tool
</p>
</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="variablelist">
<dl>
<dt>
<span class="term">Convolve Type</span>
</dt>
<dd>
<p>
<span class="emphasis"><em>Blur</em></span> mode causes each pixel affected by
the brush to be blended with neighboring pixels, thereby increasing the
similarity of pixels inside the brushstroke area.
<span class="emphasis"><em>Sharpen</em></span> mode causes each pixel to
become more different from its neighbors than it previously
was: it increases contrast inside the brushstroke area.
Whatever setting you choose here, you can reverse it
on-the-fly by holding down the Ctrl key.
</p>
</dd>
<dt>
<span class="term">Rate</span>
</dt>
<dd>
<p>
The <span class="guilabel">Rate</span> slider sets the strength of the
convolve effect.
</p>
</dd>
</dl>
</div>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="ch03s03s08.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="ch03s03.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="ch03s03s10.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">3.8. Clone Tool </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> 3.10. Dodge or Burn</td>
</tr>
</table>
</div>
</body>
</html>
|
