Re: affine transformation to rasters
- To: mathgroup at smc.vnet.net
- Subject: [mg83073] Re: affine transformation to rasters
- From: "David Park" <djmpark at comcast.net>
- Date: Fri, 9 Nov 2007 05:19:33 -0500 (EST)
- References: <fguqhg$pi7$1@smc.vnet.net>
Juan,
I think that translations and scalings were performed - but I'm not certain
of the composition of your affine transform. In any case, add a Frame to
your plot to better see what is happening.
oce = Import["ExampleData/ocelot.jpg"];
oceras = oce[[1]];
Graphics[oceras,
Frame -> True]
Graphics[GeometricTransformation[oceras,
AffineTransform[{{{-0.139, 0.263}, {0.246,
0.224}}, {0.57, -0.036}}]],
Frame -> True]
The following shows that scalings and translations are performed on Rasters.
Graphics[GeometricTransformation[oceras,
ScalingTransform[{1/200, 1/200}]],
Frame -> True]
Graphics[GeometricTransformation[oceras,
TranslationTransform[{-100, -100}]],
Frame -> True]
The DrawGraphics6 package has alternative forms of all the geometric
transforms so that they can be applied directly to pieces of graphics as
postfix operations.
Needs["DrawGraphics6`DrawingMaster`"]
Draw2D[
{oceras
// TranslateOp[{-100, -100}]
// RotateOp[Pi/4]
// ShearingTransformOp[Pi/4, {1, 0}, {0, 1}]},
Frame -> True]
--
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/
"juan flores" <juanfie at gmail.com> wrote in message
news:fguqhg$pi7$1 at smc.vnet.net...
> Hi all,
>
> I am working on fractals through IFS (Iterated Function Systems). An
> IFS ca be defined as a set of affine transformations that are
> iteratively applied to an initial image. All examples in the Wolfram
> Demonstrations Project do IFSs with polygons. When you apply an
> affine transformation to a raster image, you get the rotations,
> reflections, and shearings right, but not the translations nor the
> scalings.
>
> I am reading a jpg file with import, extracting the raster from it,
> and applying an affine transformation.
>
> oce = Import["ExampleData/ocelot.jpg"];
> oceras = oce[[1]];
> Graphics[GeometricTransformation[oceras,
> AffineTransform[{{{-0.139, 0.263},
> {0.246, 0.224}},
> {0.57, -0.036}}]]]
>
> In this case, the affine transformation is a composition of
> translation, rotation, reflection, and shearing.
>
> Any ideas on how to proceed? Any tricks?
>
> Regards,
>
> Juan Flores
> Universidad Michoacana
> Mexico
>
>