blocks|key|2597540|text|假设您有一个透明的"input.png"，首先将所有非透明像素转换为白色，然后使用"-edge“选项查找透明和白色之间的过渡：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2597541|convert+input.png+-negate+-threshold+1+-edge+1+edge.png|code-block|syntax|javascript|2597542|请注意，这不仅会勾勒出图像的轮廓，还会勾勒出图像中的任何“洞”。例如，尝试使用内置的"logo:“图像：|2597543|convert+logo:+-transparent+white+logotrans.png
convert+logotrans.png+-negate+-threshold+1+-edge+1+t.png|2597544|这将转换为|2597545|​|2597546|📷|atomic|offset|length|2597547|2597548|到这个|2597549|2597550|2597551|2597552|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/ba2de80ed2f0a867513aeb9a4dd9161f.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/286146d8f8ca6d069a58a03f4c308e97.png^0|0|0|0|0|0|0|0|1|0|0|0|0|0|0|1|1|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1F|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1G|8|@]|9|@$R|1H|S|1I|1|1J]]|A|$]]|$1|T|3|N|5|6|7|1K|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1L|8|@]|9|@]|A|$]]|$1|W|3|N|5|6|7|1M|8|@]|9|@]|A|$]]|$1|X|3|P|5|Q|7|1N|8|@]|9|@$R|1O|S|1P|1|1Q]]|A|$]]|$1|Y|3|N|5|6|7|1R|8|@]|9|@]|A|$]]|$1|Z|3|-4|5|6|7|1S|8|@]|9|@]|A|$]]]|10|$11|$5|12|13|14|A|$15|16|17|-4]]|18|$5|12|13|14|A|$15|19|17|-4]]]]

Assuming you have a transparent "input.png", first convert all nontransparent pixels to white, then use the "-edge" option to find the transitions between transparent and white:

<pre><code>convert input.png -negate -threshold 1 -edge 1 edge.png
</code></pre>

Note that this will not only outline the image but will outline any "holes" in it as well. For example, try it with the built-in "logo:" image:

<pre><code>convert logo: -transparent white logotrans.png
convert logotrans.png -negate -threshold 1 -edge 1 t.png
</code></pre>

which transforms this

<a href="https://i.stack.imgur.com/kxh2h.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kxh2h.png" alt="enter image description here"></a>

to this

<a href="https://i.stack.imgur.com/OIRzj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OIRzj.png" alt="enter image description here"></a>

blocks|key|5219422|text|假设你从这张图片开始，它有一个透明的背景：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5219423|​|5219424|📷|atomic|offset|length|5219425|5219426|您可以提取透明度并找到边缘，如下所示：|5219427|convert+penguin.png+-alpha+extract+-edge+1+-threshold+50%25+edges.png|code-block|syntax|javascript|5219428|5219429|5219430|5219431|如果你想要一个轮廓坐标列表(即白色像素)，而不是图像，你可以这样做：|5219432|convert+penguin.png+-alpha+extract+-edge+1+-threshold+50%25+-depth+8+txt:+%7C+awk+-F:+'/white/{print+$1}'
256,0
253,1
254,1
255,1
257,1
258,1
259,1
253,2
259,2
252,3
253,3
...
...|5219433|将awk及其后面的所有内容替换为more，以查看awk实际在做什么-它只是打印每个白色像素的坐标。|style|CODE|5219434|5219435|上面的像素是按行顺序出来的，而不是像轮廓那样相邻的像素一起出来。如果你想这样做，你可能更喜欢用potrace生成一个透明的SVG，如下所示：|5219436|convert+penguin.png+-alpha+extract+-threshold+50%25+pgm:-+%7C+potrace+-+--svg+<+alpha.pgm+>+result.svg|5219437|输出|BOLD|5219438|<?xml+version="1.0"+standalone="no"?>
<!DOCTYPE+svg+PUBLIC+"-//W3C//DTD+SVG+20010904//EN"
+"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg+version="1.0"+xmlns="http://www.w3.org/2000/svg"
+width="500.000000pt"+height="577.000000pt"+viewBox="0+0+500.000000+577.000000"
+preserveAspectRatio="xMidYMid+meet">
<metadata>
Created+by+potrace+1.13,+written+by+Peter+Selinger+2001-2015
</metadata>
<g+transform="translate(0.000000,577.000000)+scale(0.100000,-0.100000)"
fill="#000000"+stroke="none">
<path+d="M0+3294+l0+-2476+25+16+c31+20+104+21+152+1+20+-8+38+-14+40+-12+2+2
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0+-14+43+17+110+80+143+136+324+456+306+545+-4+21+-1+31+12+38+11+7+-402+10
-1260+11+l-1278+0+0+-2476z"/>
<path+d="M2613+5669+c17+-82+18+-107+9+-133+-7+-18+-12+-47+-12+-64+0+-18+-14
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-12+3+-7+6+566+6+1275+l1+1287+-1204+0+-1203+0+20+-101z"/>
<path+d="M4971+3138+c-20+-33+-89+-96+-165+-153+-23+-17+-103+-92+-179+-168
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3+32+11+32+20+0+8+12+42+26+75+24+58+25+66+15+145+-7+57+-25+120+-57+204+-26
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872+-2+1585+-4+1585+-2+0+-14+-15+-25+-32z"/>
<path+d="M0+358+l0+-358+458+1+c393+1+450+2+407+14+-146+37+-255+105+-435+270
-30+28+-102+83+-160+122+-173+118+-218+166+-256+271+-11+32+-13+-14+-14+-320z"/>
</g>
</svg>|5219439|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/1388ddff3a4f1917bb07aab6e7284906.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/2efd554c6eae3aa5cfc06de55558e532.png^0|0|0|0|1|0|0|0|0|0|0|0|1|1|0|0|0|0|1|3|G|4|O|3|0|0|1B|7|0|0|0|2|0|0^^$0|@$1|2|3|4|5|6|7|1M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1O|8|@]|9|@$G|1P|H|1Q|1|1R]]|A|$]]|$1|I|3|C|5|6|7|1S|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1T|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1U|8|@]|9|@]|A|$O|P]]|$1|Q|3|C|5|6|7|1V|8|@]|9|@]|A|$]]|$1|R|3|E|5|F|7|1W|8|@]|9|@$G|1X|H|1Y|1|1Z]]|A|$]]|$1|S|3|C|5|6|7|20|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|21|8|@]|9|@]|A|$]]|$1|V|3|W|5|N|7|22|8|@]|9|@]|A|$O|P]]|$1|X|3|Y|5|6|7|23|8|@$G|24|H|25|Z|10]|$G|26|H|27|Z|10]|$G|28|H|29|Z|10]]|9|@]|A|$]]|$1|11|3|-4|5|6|7|2A|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|2B|8|@$G|2C|H|2D|Z|10]]|9|@]|A|$]]|$1|14|3|15|5|N|7|2E|8|@]|9|@]|A|$O|P]]|$1|16|3|17|5|6|7|2F|8|@$G|2G|H|2H|Z|18]]|9|@]|A|$]]|$1|19|3|1A|5|N|7|2I|8|@]|9|@]|A|$O|P]]|$1|1B|3|-4|5|6|7|2J|8|@]|9|@]|A|$]]]|1C|$1D|$5|1E|1F|1G|A|$1H|1I|1J|-4]]|1K|$5|1E|1F|1G|A|$1H|1L|1J|-4]]]]

Let's say you start with this image, which has a transparent background:

<a href="https://i.stack.imgur.com/rhZ44.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rhZ44.png" alt="enter image description here"></a>

You can extract the transparency and find the edges like this:

<pre><code>convert penguin.png -alpha extract -edge 1 -threshold 50% edges.png
</code></pre>

<a href="https://i.stack.imgur.com/44Ak5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/44Ak5.png" alt="enter image description here"></a>

If, rather than an image, you want a list of the coordinates of the contour (i.e. the white pixels), you could do this instead:

<pre><code>convert penguin.png -alpha extract -edge 1 -threshold 50% -depth 8 txt: | awk -F: '/white/{print $1}'
256,0
253,1
254,1
255,1
257,1
258,1
259,1
253,2
259,2
252,3
253,3
...
...
</code></pre>

Replace <code>awk</code> and everything after it with <code>more</code> to see what the <code>awk</code> is actually doing - it is just printing the coordinates of every pixel that is white.

<hr>

The above pixels come out in row order, not like a contour where adjacent pixels come out together. If you want that, you might prefer to generate an SVG of the transparency with <code>potrace</code> like this:

<pre><code>convert penguin.png -alpha extract -threshold 50% pgm:- | potrace - --svg &lt; alpha.pgm &gt; result.svg
</code></pre>

Output

<pre><code>&lt;?xml version="1.0" standalone="no"?&gt;
&lt;!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
 "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd"&gt;
&lt;svg version="1.0" xmlns="http://www.w3.org/2000/svg"
 width="500.000000pt" height="577.000000pt" viewBox="0 0 500.000000 577.000000"
 preserveAspectRatio="xMidYMid meet"&gt;
&lt;metadata&gt;
Created by potrace 1.13, written by Peter Selinger 2001-2015
&lt;/metadata&gt;
&lt;g transform="translate(0.000000,577.000000) scale(0.100000,-0.100000)"
fill="#000000" stroke="none"&gt;
&lt;path d="M0 3294 l0 -2476 25 16 c31 20 104 21 152 1 20 -8 38 -14 40 -12 2 2
-8 35 -23 73 -49 129 -29 246 43 260 51 10 109 -12 159 -58 43 -40 44 -40 44
-15 0 41 60 120 99 130 28 7 32 11 26 30 -24 70 -15 385 16 637 44 346 171
715 351 1023 34 58 35 77 5 77 -43 0 -242 47 -277 65 -68 35 -196 130 -248
185 -83 86 -119 154 -153 286 -31 124 -38 237 -18 307 13 49 15 49 91 -15 177
-151 388 -309 477 -357 42 -23 108 -60 146 -81 76 -43 194 -83 228 -78 19 3
23 12 28 60 4 32 12 65 19 73 15 18 16 17 -35 34 -88 29 -255 122 -255 141 0
5 12 15 27 22 24 11 48 10 168 -9 77 -12 179 -22 226 -23 80 0 87 2 111 28 60
64 64 105 11 123 -21 6 -76 30 -122 51 l-84 39 -30 -21 c-21 -16 -32 -19 -40
-11 -19 19 8 54 63 84 46 25 59 27 109 22 31 -3 66 -8 79 -11 77 -16 -65 130
-178 182 -84 38 -150 45 -340 35 -225 -12 -242 -15 -322 -55 -57 -28 -68 -31
-68 -17 0 26 77 95 150 134 206 112 479 177 741 177 l97 0 -20 38 c-37 70 -10
186 68 294 54 75 56 88 23 119 -16 15 -29 36 -29 47 0 12 -4 24 -10 27 -19 12
-10 57 18 94 69 89 125 236 167 431 24 113 41 148 68 137 19 -7 43 -83 52
-162 l7 -60 33 90 c18 50 36 110 40 135 10 61 55 111 55 61 0 -11 9 -35 20
-54 29 -49 40 -235 17 -289 -9 -21 -12 -38 -8 -38 4 0 34 22 65 50 31 27 66
55 78 61 20 11 21 9 14 -22 -3 -18 -24 -72 -46 -119 -22 -48 -40 -90 -40 -94
0 -14 43 17 110 80 143 136 324 456 306 545 -4 21 -1 31 12 38 11 7 -402 10
-1260 11 l-1278 0 0 -2476z"/&gt;
&lt;path d="M2613 5669 c17 -82 18 -107 9 -133 -7 -18 -12 -47 -12 -64 0 -18 -14
-60 -31 -93 -17 -34 -28 -64 -25 -67 10 -10 49 17 129 88 43 39 84 70 92 70
23 0 17 -31 -15 -79 -17 -24 -30 -49 -30 -56 0 -6 -32 -58 -70 -115 -39 -56
-69 -104 -67 -106 4 -5 111 33 153 54 33 17 42 18 57 7 9 -7 17 -17 17 -23 0
-16 -104 -125 -134 -141 -14 -8 -26 -17 -26 -20 0 -4 23 -17 50 -30 53 -25
100 -63 100 -80 0 -19 -36 -30 -116 -36 -43 -3 -103 -8 -133 -11 l-54 -6 82
-80 c92 -90 185 -225 230 -331 34 -83 71 -217 71 -260 0 -15 5 -38 12 -50 18
-34 31 -169 29 -311 -1 -97 2 -133 12 -145 8 -9 29 -43 47 -76 19 -33 58 -96
87 -139 64 -93 107 -175 122 -233 10 -36 17 -44 49 -54 59 -18 220 -22 467 -9
127 6 316 15 420 20 184 9 267 15 311 25 46 10 364 35 451 35 64 0 93 -4 96
-12 3 -7 6 566 6 1275 l1 1287 -1204 0 -1203 0 20 -101z"/&gt;
&lt;path d="M4971 3138 c-20 -33 -89 -96 -165 -153 -23 -17 -103 -92 -179 -168
-77 -75 -145 -137 -153 -137 -8 0 -27 -21 -43 -47 -29 -47 -30 -47 -178 -99
-81 -29 -158 -53 -171 -53 -12 -1 -61 -15 -109 -31 -50 -18 -106 -30 -133 -30
-25 1 -101 -2 -170 -6 -100 -5 -136 -3 -179 10 -30 9 -70 16 -89 16 -33 0 -33
-1 -25 -32 4 -18 8 -92 8 -164 l0 -132 32 -20 c17 -12 70 -64 117 -117 68 -76
96 -119 140 -208 58 -118 106 -256 106 -302 0 -24 3 -26 23 -20 12 3 42 9 67
12 69 8 83 -18 98 -180 16 -176 45 -309 96 -446 24 -64 48 -129 54 -146 17
-50 52 -247 52 -295 0 -69 -42 -141 -129 -221 -99 -91 -141 -111 -239 -112
-91 -2 -129 14 -157 67 -23 42 -35 44 -76 14 -35 -26 -138 -36 -191 -19 -60
20 -78 45 -78 106 0 47 4 57 24 70 41 27 148 62 227 74 41 6 89 14 107 17 19
3 32 11 32 20 0 8 12 42 26 75 24 58 25 66 15 145 -7 57 -25 120 -57 204 -26
66 -50 120 -53 120 -16 -1 -49 -42 -73 -90 -56 -110 -125 -182 -277 -287 -66
-46 -158 -73 -248 -73 -82 0 -93 -4 -173 -65 -85 -65 -188 -116 -290 -143
-139 -38 -226 -46 -470 -45 -201 1 -250 4 -339 23 -57 12 -116 20 -130 17 -14
-3 -73 -22 -131 -42 -97 -34 -111 -37 -192 -33 l-87 4 -6 -40 c-4 -23 -9 -55
-12 -73 -7 -43 -51 -82 -104 -92 -25 -5 786 -9 1934 -10 l1977 -1 0 1585 c0
872 -2 1585 -4 1585 -2 0 -14 -15 -25 -32z"/&gt;
&lt;path d="M0 358 l0 -358 458 1 c393 1 450 2 407 14 -146 37 -255 105 -435 270
-30 28 -102 83 -160 122 -173 118 -218 166 -256 271 -11 32 -13 -14 -14 -320z"/&gt;
&lt;/g&gt;
&lt;/svg&gt;
</code></pre>

While it's easily done to visually outline, is it possible to have imagemagick output the coordinates of the outline of a transparent image? 

Note, by outline, I don't mean just the bounding box border, but the actual contour around an arbitrarily shaped transparent image geometry.

imagemagick - find coordinates of outline of transparent png (not border)

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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虽然视觉上勾勒轮廓很容易，但有可能让imagemagick输出透明图像的轮廓坐标吗？请注意，我所说的轮廓不只是边界框边界，而是任意形状的透明图像几何形状周围的实际轮廓。

问imagemagick -查找透明png轮廓的坐标(不是边框)
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