Re: blurry ellipse

*To*: mathgroup at smc.vnet.net*Subject*: [mg92375] Re: blurry ellipse*From*: "Solomon, Joshua" <J.A.Solomon at city.ac.uk>*Date*: Tue, 30 Sep 2008 07:33:07 -0400 (EDT)*References*: <gat9g4$ec5$1@smc.vnet.net> <gavqku$emm$1@smc.vnet.net> <gbajun$ff$1@smc.vnet.net> <gbjm2t$375$1@smc.vnet.net>

correct. thanks. j On 26/09/2008 23:01, in article gbjm2t$375$1 at smc.vnet.net, "dh" <dh at metrohm.ch> wrote: > > > Hi Solomon, > > I think this is an artefact of the original coarse grained picture. The > > convolution treats every block (square) of pixels equally. But look at > > the original picture. If you imagine some small square, you will see > > that there are more or less white pixels inside the square, depending on > > where the squre is placed. This differences will persits, because the > > convolution will simply smear the "total white" on a larger surface. > > To improve, we therefore need a more fine grained original. > > Daniel > > > > Solomon, Joshua wrote: > >> thanks. but notice, intensity also varies as you go around your ellipse. > >> j > >> > >> On 19/09/2008 10:16, in article gavqku$emm$1 at smc.vnet.net, "dh" > >> <dh at metrohm.ch> wrote: > >> > >>> n=100; > >>> > >>> pict=Table[0,{n},{n}]; > >>> > >>> Scan[(pict[[Round[n/2+n/5 Sin[#]],Round[n/2+2 > >>> > >>> n/5Cos[#]]]]=1)&,Range[0,2Pi,0.01]]; > >>> > >>> Graphics[Raster[pict]] > >>> > >>> kernel={{1,1},{1,1}}; pict=ListConvolve[kernel,pict];pict=pict/Max[pict]; > >>> > >>> Graphics[Raster[pict]] > >>> > >>> kernel={{1,1,1},{1,1,1},{1,1,1}}; > >>> > >>> pict=ListConvolve[kernel,pict];pict=pict/Max[pict]; > >>> > >>> Graphics[Raster[pict]] > >>> > >>> kernel={{1,1,1,1},{1,1,1,1},{1,1,1,1},{1,1,1,1}}; > >>> > >>> pict=ListConvolve[kernel,pict];pict=pict/Max[pict]; > >>> > >>> Graphics[Raster[pict]] > >> > >> > > > >