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 > >