Re: Radial symmetry lost during rasterization

DeWeese Thomas <[email protected]>
Newsgroups gmane.text.xml.batik.user
Message-ID <[email protected]> 
Hi Ryan,
	It looks like there is a shift of the center of the radial gradient by ~.5 a pixel 
relative to the geometry. Feel free to register a bug.

	Thomas

This version makes it a little clearer:
<?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="16"
   height="16"
   id="svg6152"
   shape-rendering="geometricPrecision"
   color-rendering="optimizeQuality"
   inkscape:version="0.48.2 r9819"
   sodipodi:docname="cluster.svg">
  <sodipodi:namedview
     pagecolor="#ffffff"
     bordercolor="#666666"
     borderopacity="1"
     objecttolerance="10"
     gridtolerance="10"
     guidetolerance="10"
     inkscape:pageopacity="0"
     inkscape:pageshadow="2"
     inkscape:window-width="1680"
     inkscape:window-height="988"
     id="namedview14"
     showgrid="false"
     inkscape:zoom="48.048722"
     inkscape:cx="5.5129408"
     inkscape:cy="8"
     inkscape:window-x="-8"
     inkscape:window-y="-8"
     inkscape:window-maximized="1"
     inkscape:current-layer="svg6152" />
  <defs
     id="defs6154">
    <linearGradient
       id="linearGradient6830">
      <stop
         id="stop6832"
         style="stop-color:#eeb111;stop-opacity:1"
         offset="0" />
      <stop
         id="stop6838"
         style="stop-color:#eeb111;stop-opacity:1"
         offset="0.80000001" />
      <stop
         id="stop6834"
         style="stop-color:#eeb111;stop-opacity:0"
         offset="1" />
    </linearGradient>
    <radialGradient
       cx="8.4242573"
       cy="7.3054457"
       r="6.0816832"
       fx="8.4242573"
       fy="7.3054457"
       id="radialGradient6836"
       xlink:href="#linearGradient6830"
       gradientUnits="userSpaceOnUse"
       gradientTransform="matrix(1,0,0,1.037037,0,-0.27057189)" />
  </defs>
  <metadata
     id="metadata6157">
    <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"
     style="display:inline"
     transform="matrix(1,0,0,0.99971334,0,0.0022932)">
    <path
       d="m 14.50594,7.3054457 a 6.0816832,6.3069305 0 1 1
-12.1633659,0 6.0816832,6.3069305 0 1 1 12.1633659,0 z"
       transform="matrix(1.3154253,0,0,1.2684459,-3.0814812,-1.2665626)"
       id="path6806"
       style="fill:#000;fill-opacity:1"
       inkscape:connector-curvature="0" />
    <path
       d="m 14.50594,7.3054457 a 6.0816832,6.3069305 0 1 1
-12.1633659,0 6.0816832,6.3069305 0 1 1 12.1633659,0 z"
       transform="matrix(1.3154253,0,0,1.2684459,-3.0814812,-1.2665626)"
       id="path6806"
       style="fill:url(#radialGradient6836);fill-opacity:1"
       inkscape:connector-curvature="0" />
  </g>
  <g
     id="layer2"
     style="display:inline"
     transform="matrix(1,0,0,0.99951699,0,0.0038645)">
    <path
       d="m 11.082178,7.3730197 a 1.2839109,1.1487623 0 1 1
-2.5678215,0 1.2839109,1.1487623 0 1 1 2.5678215,0 z"
       transform="matrix(4.6732216,0.0143752,0,5.2229872,-37.789475,-30.65004)"
       id="path6670"
       style="fill:#f7d888;fill-opacity:1"
       inkscape:connector-curvature="0" />
  </g>
  <g transform="matrix(1,0,0,0.99971334,0,0.0022932)">
    <g transform="matrix(1.3154253,0,0,1.2684459,-3.0814812,-1.2665626)">
    <circle
       cx="8.4242573"
       cy="7.3054457"
       r="1"
       fill="#F00"
      transform="matrix(1,0,0,1.037037,0,-0.27057189)"/>
    </g>
  </g>
</svg>


On Mar 28, 2012, at 5:03 PM, Ryan Gustafson wrote:

> The following SVG is essentially two circles centered on top of each
> other.  It has radial symmetry.  However, when I rasterize this to a
> 16x16 image, I get something quite obviously lacking radial symmetry.
> It appears as though things are shifted to the upper left toward
> (0,0), and smells to me like an integer truncation issue.  If I
> increase the raster dimensions, the problem becomes less pronounced,
> and ultimately unnoticeable at higher resolutions (e.g. 512x512).  I
> can likely work around this by rasterizing at high resolution and then
> scaling down to my desired resolution.
> 
> This was with Batik 1.7, on with Oracle Java 1.6.0_22 and 1.6.0_29 on Windows 7.
> 
> For reference, Inkscape will export a raster that appears correct.
> 
> Regards,
> Ryan Gustafson
> 
> ---
> 
> <?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="16"
>    height="16"
>    id="svg6152"
>    inkscape:version="0.48.2 r9819"
>    sodipodi:docname="cluster.svg">
>   <sodipodi:namedview
>      pagecolor="#ffffff"
>      bordercolor="#666666"
>      borderopacity="1"
>      objecttolerance="10"
>      gridtolerance="10"
>      guidetolerance="10"
>      inkscape:pageopacity="0"
>      inkscape:pageshadow="2"
>      inkscape:window-width="1680"
>      inkscape:window-height="988"
>      id="namedview14"
>      showgrid="false"
>      inkscape:zoom="48.048722"
>      inkscape:cx="5.5129408"
>      inkscape:cy="8"
>      inkscape:window-x="-8"
>      inkscape:window-y="-8"
>      inkscape:window-maximized="1"
>      inkscape:current-layer="svg6152" />
>   <defs
>      id="defs6154">
>     <linearGradient
>        id="linearGradient6830">
>       <stop
>          id="stop6832"
>          style="stop-color:#eeb111;stop-opacity:1"
>          offset="0" />
>       <stop
>          id="stop6838"
>          style="stop-color:#eeb111;stop-opacity:1"
>          offset="0.80000001" />
>       <stop
>          id="stop6834"
>          style="stop-color:#eeb111;stop-opacity:0"
>          offset="1" />
>     </linearGradient>
>     <radialGradient
>        cx="8.4242573"
>        cy="7.3054457"
>        r="6.0816832"
>        fx="8.4242573"
>        fy="7.3054457"
>        id="radialGradient6836"
>        xlink:href="#linearGradient6830"
>        gradientUnits="userSpaceOnUse"
>        gradientTransform="matrix(1,0,0,1.037037,0,-0.27057189)" />
>   </defs>
>   <metadata
>      id="metadata6157">
>     <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"
>      style="display:inline"
>      transform="matrix(1,0,0,0.99971334,0,0.0022932)">
>     <path
>        d="m 14.50594,7.3054457 a 6.0816832,6.3069305 0 1 1
> -12.1633659,0 6.0816832,6.3069305 0 1 1 12.1633659,0 z"
>        transform="matrix(1.3154253,0,0,1.2684459,-3.0814812,-1.2665626)"
>        id="path6806"
>        style="fill:url(#radialGradient6836);fill-opacity:1"
>        inkscape:connector-curvature="0" />
>   </g>
>   <g
>      id="layer2"
>      style="display:inline"
>      transform="matrix(1,0,0,0.99951699,0,0.0038645)">
>     <path
>        d="m 11.082178,7.3730197 a 1.2839109,1.1487623 0 1 1
> -2.5678215,0 1.2839109,1.1487623 0 1 1 2.5678215,0 z"
>        transform="matrix(4.6732216,0.0143752,0,5.2229872,-37.789475,-30.65004)"
>        id="path6670"
>        style="fill:#f7d888;fill-opacity:1"
>        inkscape:connector-curvature="0" />
>   </g>
> </svg>
> 
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