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Re: Drawing on an image in Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126372] Re: Drawing on an image in Mathematica
  • From: JUN <noeckel at gmail.com>
  • Date: Fri, 4 May 2012 06:26:58 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <jnven4$8ee$1@smc.vnet.net>

On Thursday, May 3, 2012 7:25:40 PM UTC-7, Julian Francis wrote:
> Dear all,
> 
> I have a binary image in which I'd like to use the mouse to draw
> (freehand) on top of the image, and use this in Mathematica.
> 
> Presently, I can import the image into a painting program, use its
> sketching facilities, then cut and paste into Mathematica. I can
> extract the matrix if I wish by using ImageData.
> 
> Is there a way of drawing on the image directly in Mathematica to save
> me cutting and pasting between programs?
> 
> I've worked out how to create a graphic and draw into it using the
> Mathematica graphics drwaing tools, but my problem is either the
> graphic is far too large, or if I shrink it down
> (I want to work on matrices 16x16), the resulting picture is far too
> small. I want to draw into a matrix 16x16, but it be large enough for
> me to see easily.
> 
> Thanks,
> Julian.

The image has to be put into a Graphics box, and you can do that using the Inset command:

im = RandomImage[1, {16, 16}];
Graphics[Inset[im, Automatic, Automatic, Scaled[1]]]

Here I've just used a random image and scaled it to fill the default Graphics width. Now you can double-click on the graphic and press Control-t to get the drawing tools, and they should work as you want.

I think what you want to do after you're done editing is to convert the result back to an image. To do that, you could type:

Rasterize[      , "Image", ImageSize -> 16]

and copy the edited graphic from the previous cell back into the empty space I left in the Rasterize command. The result is again an image of the original dimensions.

Jens




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