| Mathematica: (supports both PNG and GIF)
(1)
image = Import["denise.png","PNG"] or
image = Import["denise.gif","GIF"]
A = image[[1,1]]/255.;
(2)
ListDensityPlot[A,Mesh->False,
AspectRatio->Automatic]
-- or --
Show[Graphics[Raster[A]],
AspectRatio->Automatic]
blurA = ListConvolve[Table[1/25,{5},{5}],A];
Show[Graphics[Raster[blurA]],
AspectRatio->Automatic]
(3)
B = Fourier[A];
delete
higher frequencies
B[[Range[30,278],All]]=0;
B[[All,Range[30,202]]]=0;
now invert & display
Show[Graphics[Raster[
Re[InverseFourier[B]]
]], AspectRatio->Automatic]
|
Matlab: (doesn't support GIF)
(1)
[A,map] = imread('denise.png','PNG');
(2)
image(A);
colormap(gray(256)) % (if necessary)
imagesc(filter2(ones(5,5),A,'valid'));
(3)
B = fft2(A);
delete
higher frequencies
B(:,30:202)=0;
B(30:278,:)=0;
now invert & display
imagesc(real(ifft2(B)));
|
| Maple:
- does not support reading image files
- can plot to a GIF file (but not PNG)
|
IDL: (doesn't support GIF)
(1)
A = read_png('denise.png')
(2)
tv, A
tv, smooth(A,5), 250, 0
(3)
B = fft(A,1)
z=size(A)
freq=dist(z[1],z[2])
tvscl, fft(B * (freq lt 40), -1)
|
