[Inkscape-devel] question about filter/arithmetic

9 Oct 2012


      Hi,
I hope it's ok to post the following test case to get your opinion.
It's about filter/arithmetic. I don't get the same result in inkscape and
in squiggle (and for me both look wrong)
final filter in inkscape (0.48.3) "does nothing" the result looks 99% like
the initial background
squiggle is better you see the diagonal but not all pixels are black
I expected every pixel at the top right above the diagonal in final image
would be black (as in the included png)
because in the top right  r image (=g image =b image) > r background
so lighter (image,background) = image
so k2 * lighter (image,background) + k3 * image with k2 = 1 and k3 = -1
  = lighter (image,background) - image
  = image - image
  = 0
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style="font-size:48px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#f64a00;fill-opacity:1;stroke:none;font-family:Nimbus
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Mono L;-inkscape-font-specification:Nimbus Mono L"><tspan
         x="415.90714"
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         id="tspan4707">OK</tspan></text>
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       xml:space="preserve"
style="font-size:10.02463627px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#f64a00;fill-opacity:1;stroke:none;font-family:Nimbus
Mono L;-inkscape-font-specification:Nimbus Mono L"><tspan
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         id="tspan4853">in Inkscape 0.48.3.1 r9886 </tspan><tspan
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         id="tspan5969">it looks like the background </tspan></text>
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Thank you

[Inkscape-devel] question about filter/arithmetic

pennec victor