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Re: overimpose graphics on an imported image

• To: mathgroup at smc.vnet.net
• Subject: [mg106121] Re: [mg106104] overimpose graphics on an imported image
• From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
• Date: Sat, 2 Jan 2010 05:04:14 -0500 (EST)
• References: <201001011037.FAA05346@smc.vnet.net>

Hi,

tell Mathematica about your plotting-range: 

img = Import["http://sipi.usc.edu/database/misc/5.1.12.tiff";];
{nx, ny} = ImageDimensions[img];
ImageCompose[img, {Graphics[{Red, Rectangle[{0, 0}, {nx/2, ny/2}]}, 
   PlotRange -> {{0, nx}, {0, ny}}], 0.5}]


Cheers
Patrick

On Fri, 2010-01-01 at 05:37 -0500, alexxx.magni at gmail.com wrote:
> 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
> 

• References:
  • overimpose graphics on an imported image
    • From: "alexxx.magni@gmail.com" <alexxx.magni@gmail.com>