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5 <title>ImageMagick: Image Gradients</title>
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47
48<p class="lead magick-description">An image gradient creates a gradual blend of one color whose shape is linear, circular, or elliptical.</p>
49
50<p>For a linear gradient, use a filename of:</p>
51
52<pre>
53gradient:
54gradient:<var>color1</var>-<var>color2</var>
55</pre>
56
57<p> For a radial gradient, use a filename of:</p>
58
59<pre>
60radial-gradient:
61radial-gradient:<var>color1</var>-<var>color2</var>
62</pre>
63
64<p>Where <var>color1</var> is the from color and <var>color2</var> is the to color as described in more detail below. The default is white for <var>color1</var> and black for <var>color2</var>, i.e., <code>white-black</code>.</p>
65
66<p>The default for a linear gradient starts with <var>color1</var> at the top of the image and <var>color2</var> at the bottom of the image. Similarly, the default for a radial gradient starts with <var>color1</var> at the center of the image and <var>color2</var> at the boundary of the image.</p>
67
68<p>Gradient colors may be any valid <a href="http://www.imagemagick.org/www/color.html">color</a> accepted by ImageMagick. The named colors of <code>black</code>, <code>white</code>, or <code>gray<var>XX</var></code> are non-linear gray gradients; whereas <code>gray<var>XX[%]</var></code> is a linear gray gradient. For Unix systems, enclose <code>rgb(a)</code> and hex colors in quotes. Use double quotes, if using variables for the values.</p>
69
70<p>Here is an example black to white linear gradient:</p>
71
72<pre>
73convert -size 256x256 gradient: linear.png
74</pre>
75
76<p>If you want a black to white radial gradient, try:</p>
77
78<pre>
79convert -size 256x256 radial-gradient: radial.png
80</pre>
81
82<p>As of IM 6.9.2.5, gradients have been modified to be more flexible through the use of <a href="command-line-options.html#define">-define</a>:</p>
83
84<table class="table table-condensed table-striped">
85 <tr>
86 <td><code>-define gradient:bounding-box=<var>width</var>x<var>height</var>+<var>x</var>+<var>y</var></code></td>
87 <td>Limits the gradient to a larger or smaller region than the image
88 dimensions. If the region defined by the bounding box is smaller than the
89 image, color1 is the color of the background.</td>
90 </tr>
91
92 <tr>
93 <td><code>-define gradient:vector="<var>x1</var>,<var>y1</var> <var>x2</var>,<var>y2</var>"</code></td>
94 <td>Specifies the direction of the linear gradient going from vector1
95 (x1,y1) to vector2 (x2,y2). Color1 (from-color) is located at vector
96 position x1,y1 and color2 (to-color) is located at vector position
97 x2,y2.</td>
98 </tr>
99
100 <tr>
101 <td><code>-define gradient:center=<var>x</var>,<var>y</var></code></td>
102 <td>Specifies the coordinates of the center point for the radial gradient.
103 The default is the center of the image.</td>
104 </tr>
105
106 <tr>
107 <td><code>-define gradient:radii=<var>x</var>,<var>y</var></code></td>
108 <td>Specifies the x and y radii of the gradient. If the x radius and the y
109 radius are equal, the shape of the radial gradient is a circle. If
110 they differ, the shape is an ellipse. The default values are the
111 maximum of the half width and half height of the image.</td>
112 </tr>
113
114 <tr>
115 <td><code>-define gradient:angle=<var>angle</var></code></td>
116 <td>For a linear gradient, this define specifies the direction in degrees of the gradient
117 going from color1 to color2 in a clockwise positive manner relative to the
118 positive x axis (east). For a radial gradient, this define specifies the rotation
119 of the gradient in a clockwise positive manner from its normal X-Y
120 orientation.</td>
121 </tr>
122</table>
123
124
125<p>We also support a two convenience defines for setting the linear gradient direction and the radial gradient shape.</p>
126
127<table class="table table-condensed table-striped">
128 <tr>
129 <td><code>-define gradient:direction=<em>{NorthWest, North, Northeast, West, East, SouthWest, South, SouthEast}</em></code></td>
130 <td>Specify the direction of the linear gradient towards the
131 top/bottom/left/right or diagonal corners.</td>
132 </tr>
133
134 <tr>
135 <td><code>-define gradient:extent=<em>{Circle, Diagonal, Ellipse, Maximum, Minimum}</em></code></td>
136 <td>Specify the shape of an image centered radial gradient. Circle and
137 Maximum draw a circular radial gradient even for rectangular shaped images
138 of radius equal to the larger of the half-width and half-height of the
139 image. The Circle and Maximum options are both equivalent to the default
140 radial gradient. The Minimum option draws a circular radial gradient
141 even for rectangular shaped images of radius equal to the smaller of the
142 half-width and half-height of the image. The Diagonal option draws a
143 circular radial gradient even for rectangular shaped images of radius equal
144 to the half-diagonal of the image. The Ellipse options draws an elliptical
145 radial gradient for rectangular shaped images of radii equal to half the
146 width and half the height of the image.</td>
147 </tr>
148</table>
149
150<h3>Examples</h3>
151
152<p>The default linear gradient can be generated in any of the following ways (or by reversing the direction and swapping <var>color1</var> and <var>color2</var>):</p>
153
154<pre>
155convert -size 256x128 -gradient:white-black default_linear_gradient.png
156convert -size 256x128 -define gradient:direction=north -gradient:black-white default_linear_gradient.png
157convert -size 256x128 -define gradient:angle=-90 -gradient:black-white default_linear_gradient.png
158</pre>
159
160<p>The equivalent of</p>
161
162<pre>
163convert -size 128x256 -gradient: -rotate 90 east_linear_gradient.png
164</pre>
165
166<p>can be generated by either of the following (or by reversing the direction and swapping <var>color1</var> and <var>color2</var>):</p>
167
168<pre>
169convert -size 256x128 -define gradient:direction=east gradient:black-white east_linear_gradient.png
170convert -size 256x128 -define gradient:angle=0 gradient:black-white east_linear_gradient.png
171</pre>
172
173
174<p>Examples of radial gradients going from black in the center to white at the boundary for the cases of <code>maximum</code>, <code>circle</code>, <code>default</code>, <code>minimum</code>, <code>diagonal</code>, <code>ellipse</code> and 45 degree rotated ellipse, respectively, follow:</p>
175
176
177<pre>
178convert -size 256x128 gradient:black-white maximum_radial_gradient.png
179convert -size 256x128 -define gradient:radii=128,128 gradient:black-white maximum_radial_gradient.png
180convert -size 256x128 -define gradient:extent=minimum gradient:black-white minimum_radial_gradient.png
181convert -size 256x128 -define gradient:radii=64,64 gradient:black-white minimum_radial_gradient.png
182convert -size 256x128 -define gradient:extent=diagonal gradient:black-white diagonal_radial_gradient.png
183convert -size 256x128 -define gradient:extent=ellipse gradient:black-white ellipse_radial_gradient.png
184convert -size 256x128 -define gradient:radii=128,64 gradient:black-white ellipse_radial_gradient.png
185convert -size 256x256 -define gradient:radii=128x64 -define gradient:angle=45 gradient:black-white ellipse_radial_gradient.png
186</pre>
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