ClipPathImage and image format?

Hi,
I'm trying to use the ClipPathImage API call to set a clip mask. Is
the image containing the clip mask required to be in a particular
format (like TIFF)? I have an SVG image containing a clip mask that I
created using InkScape, and when I load it and call ClipPathImage, the
clip mask seems to be ignored. The SVG file looks like (in part):
    <clipPath
       id="clipPath5247">
      <path
         d="M 129.74603,36.867724 L 106.04271,60.116807 L
111.75698,92.823295 L 82.321057,77.464462 L 52.981145,93.005913 L
58.492063,60.264548 L 34.644733,37.163206 L 67.486589,32.286763 L
82.088041,2.4678965 L 96.874506,32.195454 L 129.74603,36.867724 z "
         transform="matrix(1.6107469,0,0,1.9312731,1.9105408,0.9195656)"
         style="opacity:0.46330273;fill:#ffff00;fill-opacity:1;fill-rule:evenodd;stroke:#000000;stroke-width:1px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
         id="path5249" />
    </clipPath>

and my code looks like (in part):

  image_info=CloneImageInfo((ImageInfo *) NULL);
  strcpy(image_info->filename, "/home/tjc/ImageLib/clip.svg");
  image=ReadImage(image_info, &exception);
  ClipPathImage(image, "clipPath5247", 1);
  NegateImage(image, 0);
  strcpy(image->filename, "/home/tjc/ImageLib/out.png");
  WriteImage(image_info, image);

If I look at the return value of the ClipPathImage call, it returns
MagickFail, and when I look at out.png, the entire image is negated,
not just the part within the clip mask.

Any suggestions? If the image containing the clip mask has to be a
TIFF, is there a way to create such an image using a free program
available for GNU/Linux? InkScape can't seem to save as TIFF, and when
I use gm convert to convert my .svg image to a .tiff, it doesn't seem
to preserve the clipping path.

Thanks,
Tim

-- 
Tim Chevalier * catamorphism.org * Often in error, never in doubt
"Time flies like an arrow.  Fruit flies like a banana.  Syntax rules
like a macro." -- Albert Lai

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