Re: blurry ellipse
- To: mathgroup at smc.vnet.net
- Subject: [mg92253] Re: blurry ellipse
- From: dh <dh at metrohm.ch>
- Date: Wed, 24 Sep 2008 03:32:42 -0400 (EDT)
- References: <gat9g4$ec5$1@smc.vnet.net> <gavqku$emm$1@smc.vnet.net> <gbajun$ff$1@smc.vnet.net>
Hi Solomon,
I think this is an artefact of the original coarse grained picture. The
convolution treats every block (square) of pixels equally. But look at
the original picture. If you imagine some small square, you will see
that there are more or less white pixels inside the square, depending on
where the squre is placed. This differences will persits, because the
convolution will simply smear the "total white" on a larger surface.
To improve, we therefore need a more fine grained original.
Daniel
Solomon, Joshua wrote:
> thanks. but notice, intensity also varies as you go around your ellipse.
> j
>
> On 19/09/2008 10:16, in article gavqku$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]]
>
>
--
Daniel Huber
Metrohm Ltd.
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