我正在尝试使用Imagick将svg文件（包含图表）转换为png文件，但是我收到以下错误：
Fatal error: Uncaught exception 'ImagickException' with message 'no decode delegate for this image format `' @ error/blob.c/BlobToImage/346
代码：
$chart = '1201900945.svg';
$image = new Imagick();
$image->setBackgroundColor(new ImagickPixel('transparent'));
$image->readImageBlob($chart);
$image->setImageFormat("png24");
//$image->resizeImage(1024, 768, imagick::FILTER_LANCZOS, 1);
$image->writeImage('svgtmp/image22.png');
我的SVG文件包含简单的苹果绘制svg，需要通过上面的代码转换为png，但它返回我上面提到的错误：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:cc="http://creativecommons.org/ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
version="1.1"
width="210mm"
height="210mm"
id="svg2"
inkscape:version="0.48.0 r9654"
sodipodi:docname="apple.svg">
<sodipodi:namedview
pagecolor="#ffffff"
bordercolor="#666666"
borderopacity="1"
objecttolerance="10"
gridtolerance="10"
guidetolerance="10"
inkscape:pageopacity="0"
inkscape:pageshadow="2"
inkscape:window-width="1366"
inkscape:window-height="742"
id="namedview63"
showgrid="false"
inkscape:zoom="0.4112381"
inkscape:cx="376.9106"
inkscape:cy="372.04724"
inkscape:window-x="0"
inkscape:window-y="0"
inkscape:window-maximized="1"
inkscape:current-layer="svg2" />
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id="defs4">
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id="linearGradient4579">
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id="stop4581"
style="stop-color:#ff4a00;stop-opacity:0"
offset="0" />
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id="stop4583"
style="stop-color:#ff3500;stop-opacity:0.5958904"
offset="1" />
</linearGradient>
<linearGradient
id="linearGradient4547">
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id="stop4549"
style="stop-color:#ff9e00;stop-opacity:0.56849313"
offset="0" />
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id="stop4551"
style="stop-color:#ff3f00;stop-opacity:0"
offset="1" />
</linearGradient>
<linearGradient
id="linearGradient4221">
<stop
id="stop4223"
style="stop-color:#ffff00;stop-opacity:0.56849313"
offset="0" />
<stop
id="stop4225"
style="stop-color:#ffff00;stop-opacity:0"
offset="1" />
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<linearGradient
id="linearGradient4207">
<stop
id="stop4209"
style="stop-color:#ffffff;stop-opacity:1"
offset="0" />
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id="stop4211"
style="stop-color:#ffffff;stop-opacity:0.55479455"
offset="1" />
</linearGradient>
<linearGradient
id="linearGradient4197">
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id="stop4199"
style="stop-color:#0000ff;stop-opacity:1"
offset="0" />
<stop
id="stop4201"
style="stop-color:#000000;stop-opacity:0"
offset="1" />
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id="linearGradient4189">
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style="stop-color:#dc1f00;stop-opacity:1"
offset="0" />
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style="stop-color:#602000;stop-opacity:1"
offset="0" />
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id="stop4147"
style="stop-color:#130000;stop-opacity:0.99315071"
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id="linearGradient3973">
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style="stop-color:#e02000;stop-opacity:1"
offset="0" />
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id="stop3977"
style="stop-color:#e08400;stop-opacity:1"
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style="stop-color:#e0e800;stop-opacity:1"
offset="0" />
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offset="0.5" />
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style="stop-color:#e0a860;stop-opacity:1"
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<linearGradient
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style="stop-color:#e07200;stop-opacity:1"
offset="0" />
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offset="0.5" />
<stop
id="stop3939"
style="stop-color:#b22000;stop-opacity:1"
offset="1" />
</linearGradient>
<radialGradient
cx="368.87323"
cy="710.10864"
r="223.09859"
fx="368.87323"
fy="710.10864"
id="radialGradient3111"
xlink:href="#linearGradient4207"
gradientUnits="userSpaceOnUse"
gradientTransform="matrix(1,0,0,0.3068182,0,492.23439)" />
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r="33.539486"
fx="128.05986"
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xlink:href="#linearGradient4161"
gradientUnits="userSpaceOnUse"
gradientTransform="matrix(1,0,0,0.31060608,0,211.0294)" />
<radialGradient
cx="128.05986"
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xlink:href="#linearGradient4221"
gradientUnits="userSpaceOnUse"
gradientTransform="matrix(1,0,0,0.31060608,0,211.0294)" />
<linearGradient
x1="139.53831"
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xlink:href="#linearGradient4143"
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<linearGradient
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<linearGradient
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id="linearGradient3121"
xlink:href="#linearGradient4189"
gradientUnits="userSpaceOnUse" />
</defs>
<metadata
id="metadata7">
<rdf:RDF>
<cc:Work
rdf:about="">
<dc:format>image/svg+xml</dc:format>
<dc:type
rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
<dc:title />
</cc:Work>
</rdf:RDF>
</metadata>
<g
id="layer1"
transform="matrix(1.2002804,0,0,1.2159729,-77.833554,-287.26679)">
<g
transform="matrix(3.1665674,0,0,3.1665674,-44.904079,-622.63834)"
id="g3097">
<path
d="m 54.894578,443.64142 c 3.44888,8.36726 39.911622,16.55659 55.206792,17.87984 15.29516,1.32325 27.05718,1.50531 48.84454,-0.11562 21.78735,-1.62093 45.73974,-11.66001 52.28116,-18.39023 z"
id="path4375"
style="fill:#edeceb;fill-opacity:1;stroke:#989798;stroke-width:1.15490627px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
inkscape:connector-curvature="0" />
<g
transform="matrix(0.42625338,0,0,0.33832982,-21.458546,196.25751)"
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transform="matrix(1,0,0,1.2037037,-6.3380258,-166.20105)"
id="path4099"
style="fill:#e0e8e0;fill-opacity:1;fill-rule:nonzero;stroke:#989798;stroke-width:3.64586163;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
inkscape:connector-curvature="0" />
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transform="matrix(0.78658688,0,0,0.81990814,72.384361,105.46388)"
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id="path4385"
style="fill:none;stroke:#b1b1b1;stroke-width:0.98127991px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
inkscape:connector-curvature="0" />
<path
d="m 131.82306,284.865 c -49.404744,-0.32154 -92.381306,34.28636 -83.869434,78.35982 8.51186,44.07346 38.04948,78.28678 83.869434,78.35981 0.25017,4.1e-4 0.49843,-0.009 0.74723,-0.0127 0.18447,10e-4 0.36955,-0.003 0.55397,0 0.2488,0.003 0.49705,0.0131 0.74723,0.0127 45.81995,-0.073 75.35756,-34.28635 83.86943,-78.35981 8.51187,-44.07346 -34.46469,-78.68136 -83.86943,-78.35982 -0.34506,0.002 -0.68743,0.018 -1.03066,0.0255 -0.33892,-0.007 -0.67703,-0.0232 -1.01777,-0.0255 z"
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d="m 194.63066,316.01798 c 37.45958,22.54965 8.94768,92.02251 -16.76975,106.20837 -33.53793,19.13323 31.09337,-53.62205 17.1467,-70.72027 -13.82996,-16.95512 -14.56938,-36.62953 -0.37695,-35.4881 z"
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</svg>
导致此错误的原因是什么？