GraphicsMagick not applying svg filters while converting to png

Question

Can someone help identify the problem here. Consider this SVG markup.

<svg id="paper" version="1.1" viewBox="0 0 474.00001 477.99998" style="position: relative; opacity: 1;">
    <desc style="-webkit-tap-highlight-color: rgba(0, 0, 0, 0);">Configurateur Predesire</desc>
    <defs style="-webkit-tap-highlight-color: rgba(0, 0, 0, 0);"/>
    <defs>
        <filter id="f1" x="0%" y="0%" width="100%" height="100%">
            <feColorMatrix result="original" id="c1" type="matrix" values="0.6 0 0 0 0 1 0.2 0 0 0 0 -0.2 0.1 0 0 -0.2 -0.4 -0.1 1 0"/>
        </filter>
    </defs>
    <image x="0" y="0" width="474.00001" height="477.99998" filter="url('#f1')"  id="svg_1" xlink:href="http://25.media.tumblr.com/8b045d92c3ef2f903cb8fd6a3801e26a/tumblr_mtl5yfKajA1spwwv4o1_500.jpg"/>
</svg>

When I try to convert this svg to png via GraphicsMagick:

convert item.svg item.png

Filters are not applied. However, If I use any other svg (generated by Inkscape/AI etc..) it converts successfully.

I think that GraphicsMagick does not support filter in svg