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overimpose graphics on an imported image

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106104] overimpose graphics on an imported image
  • From: "alexxx.magni at gmail.com" <alexxx.magni at gmail.com>
  • Date: Fri, 1 Jan 2010 05:37:31 -0500 (EST)

hi people,
I wonder if it is just me being dumb, but I'm unable to perform what I
thought was a very simple operation:

having imported an image of (Lx,Ly) pixels, draw above it an empty
rectangle at coordinates (x0,y0) (x1,y1) (say, lower left and upper
right corners).

Say for example that I want to overimpose on image i1 a rectangle
covering a 10% portion, if I use this:

ImageCompose[i1, Graphics[Rectangle[{0, 0}, {0.1*Lx, 0.1*Ly}]]]

I have (apart from a filled rectangle instead of empty, but I can deal
with it later)
a huge rectangle covering all of it!
How these coordinates interact?

Thanks for any help...


Alessandro Magni


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