Fail:Window function (rectangular).png
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See fail ja sellest kastist allapoole jääv kirjeldus pärinevad kesksest failivaramust Wikimedia Commons. | Faili lehekülg Commonsis |
Projektist en.wikipedia Commonsisse teisaldanud Tiaguito.
Lühikirjeldus
KirjeldusWindow function (rectangular).png | rectangular window and frequency response | |||||
Kuupäev | ||||||
Allikas | Üleslaadija oma töö | |||||
Autor | Bob K (original version), Olli Niemitalo | |||||
Luba (Faili edasikasutus) |
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Teised versioonid |
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Source code InfoField | The script below generates these .png images:
This script has not been tested in MATLAB. See the individual file histories for the simpler MATLAB scripts that were the basis of this script. Generation of svg files by minor modification of the script displayed visual artifacts and renderer incompatibilities that could not be easily fixed. The current script fixes the visual artifacts in the png file as a post-processing step. The script generates a semi-transparent grid by taking a weighted average of two images, one with the grid and one without.Matlabfunction plotWindowLayer (w, N, gridded, wname, wspecifier)
M=32;
k=0:N-1;
dr = 120;
H = abs(fft([w zeros(1,(M-1)*N)]));
H = fftshift(H);
H = H/max(H);
H = 20*log10(H);
H = max(-dr,H);
figure('Position',[1 1 1200 520])
subplot(1,2,1)
set(gca,'FontSize',28)
area(k,w,'FaceColor', [0 1 1],'edgecolor', [1 1 0],'linewidth', 2)
xlim([0 N-1])
if (min(w) >= -0.01)
ylim([0 1.05])
set(gca,'YTick', [0 : 0.1 : 1])
ylabel('amplitude','position',[-16 0.525 0])
else
ylim([-1 5])
set(gca,'YTick', [-1 : 1 : 5])
ylabel('amplitude','position',[-16 2 0])
endif
set(gca,'XTick', [0 : 1/8 : 1]*(N-1))
set(gca,'XTickLabel',[' 0'; ' '; ' '; ' '; ' '; ' '; ' '; ' '; 'N-1'])
grid(gridded)
set(gca,'LineWidth',2)
set(gca,'gridlinestyle','-')
xlabel('samples')
if (strcmp (wspecifier, ""))
title(cstrcat(wname,' window'))
else
title(cstrcat(wname,' window (', wspecifier, ')'))
endif
set(gca,'Position',[0.08 0.11 0.4 0.8])
set(gca,'XColor',[1 0 1])
set(gca,'YColor',[1 0 1])
subplot(1,2,2)
set(gca,'FontSize',28)
h = stem(([1:M*N]-1-M*N/2)/M,H,'-');
set(h,'BaseValue',-dr)
ylim([-dr 6])
set(gca,'YTick', [0 : -10 : -dr])
set(findobj('Type','line'),'Marker','none','Color',[0 1 1])
xlim([-M*N/2 M*N/2]/M)
grid(gridded)
set(findobj('Type','gridline'),'Color',[.871 .49 0])
set(gca,'LineWidth',2)
set(gca,'gridlinestyle','-')
ylabel('decibels')
xlabel('bins')
title('Frequency response')
set(gca,'Position',[0.59 0.11 0.4 0.8])
set(gca,'XColor',[1 0 1])
set(gca,'YColor',[1 0 1])
endfunction
function plotWindow (w, wname, wspecifier = "", wfilespecifier = "")
if (strcmp (wfilespecifier, ""))
wfilespecifier = wspecifier;
endif
N = size(w)(2);
B = N*sum(w.^2)/sum(w)^2 % noise bandwidth (bins), set N = 4096 to get an accurate estimate
plotWindowLayer(w, N, "on", wname, wspecifier); % "gridded" = "on"
print temp1.png -dpng "-S2500,1165"
close
plotWindowLayer(w, N, "off", wname, wspecifier); % "gridded" = "off"
print temp2.png -dpng "-S2500,1165"
close
% I'm not sure what's going on here, but it looks like the author might have been able
% to save himself some time by using set(gca,"Layer","top") and set(gca,"Layer","bottom").
I = imread ("temp1.png");
J = imread ("temp2.png");
info = imfinfo ("temp1.png");
w = info.Width;
c = 1-(double(I(:,1:w/2,1))+2*double(J(:,1:w/2,1)))/(255*3);
m = 1-(double(I(:,1:w/2,2))+2*double(J(:,1:w/2,2)))/(255*3);
y = 1-(double(I(:,1:w/2,3))+2*double(J(:,1:w/2,3)))/(255*3);
c = ((c != m) | (c != y)).*(c > 0).*(1-m-y);
I(:,1:w/2,1) = 255*(1-c-m-y + 0*m + 0*y + 0*c);
I(:,1:w/2,2) = 255*(1-c-m-y + 0*m + 0*y + 0.4*c);
I(:,1:w/2,3) = 255*(1-c-m-y + 0*m + 0*y + 0.6*c);
c = 1-(double(I(:,w/2+1:w,1))+2*double(J(:,w/2+1:w,1)))/(255*3);
m = 1-(double(I(:,w/2+1:w,2))+2*double(J(:,w/2+1:w,2)))/(255*3);
y = 1-(double(I(:,w/2+1:w,3))+2*double(J(:,w/2+1:w,3)))/(255*3);
c = ((c != m) | (c != y)).*c;
I(:,w/2+1:w,1) = 255*(1-c-m-y + 0*m + 0*y + 0.8710*c);
I(:,w/2+1:w,2) = 255*(1-c-m-y + 0*m + 0*y + 0.49*c);
I(:,w/2+1:w,3) = 255*(1-c-m-y + 0*m + 0*y + 0*c);
if (strcmp (wfilespecifier, ""))
imwrite (I, cstrcat('Window function and frequency response - ', wname, '.png'));
else
imwrite (I, cstrcat('Window function and frequency response - ', wname, ' (', wfilespecifier, ').png'));
endif
endfunction
N=128;
k=0:N-1;
w = 0.42 - 0.5*cos(2*pi*k/(N-1)) + 0.08*cos(4*pi*k/(N-1));
plotWindow(w, "Blackman")
w = 0.355768 - 0.487396*cos(2*pi*k/(N-1)) + 0.144232*cos(4*pi*k/(N-1)) -0.012604*cos(6*pi*k/(N-1));
plotWindow(w, "Nuttall", "continuous first derivative")
w = 1 - 1.93*cos(2*pi*k/(N-1)) + 1.29*cos(4*pi*k/(N-1)) -0.388*cos(6*pi*k/(N-1)) +0.032*cos(8*pi*k/(N-1));
plotWindow(w, "Flat top")
w = 1 - 1.93*cos(2*pi*k/(N-1)) + 1.29*cos(4*pi*k/(N-1)) -0.388*cos(6*pi*k/(N-1)) +0.028*cos(8*pi*k/(N-1));
plotWindow(w, "SRS flat top")
w = ones(1,N);
plotWindow(w, "Rectangular")
w = (N/2 - abs([0:N-1]-(N-1)/2))/(N/2);
plotWindow(w, "Triangular")
w = 0.5 - 0.5*cos(2*pi*k/(N-1));
plotWindow(w, "Hann")
w = 0.53836 - 0.46164*cos(2*pi*k/(N-1));
plotWindow(w, "Hamming", "alpha = 0.53836")
alpha = 0.5;
w = ones(1,N);
n = -(N-1)/2 : -alpha*N/2;
L = length(n);
w(1:L) = 0.5*(1+cos(pi*(abs(n)-alpha*N/2)/((1-alpha)*N/2)));
w(N : -1 : N-L+1) = w(1:L);
plotWindow(w, "Tukey", "alpha = 0.5")
w = sin(pi*k/(N-1));
plotWindow(w, "Cosine")
w = sinc(2*k/(N-1)-1);
plotWindow(w, "Lanczos")
w = ((N-1)/2 - abs([0:N-1]-(N-1)/2))/((N-1)/2);
plotWindow(w, "Bartlett")
sigma = 0.4;
w = exp(-0.5*( (k-(N-1)/2)/(sigma*(N-1)/2) ).^2);
plotWindow(w, "Gaussian", "sigma = 0.4")
w = 0.62 -0.48*abs(k/(N-1) -0.5) +0.38*cos(2*pi*(k/(N-1) -0.5));
plotWindow(w, "Bartlett–Hann")
alpha = 2;
w = besseli(0,pi*alpha*sqrt(1-(2*k/(N-1) -1).^2))/besseli(0,pi*alpha);
plotWindow(w, "Kaiser", "alpha = 2")
alpha = 3;
w = besseli(0,pi*alpha*sqrt(1-(2*k/(N-1) -1).^2))/besseli(0,pi*alpha);
plotWindow(w, "Kaiser", "alpha = 3")
tau = N-1;
epsilon = 0.1;
t_cut = tau * (0.5 - epsilon);
T_in = abs(k - 0.5 * tau);
z_exp = ((t_cut - 0.5 * tau) ./ (T_in - t_cut) + (t_cut - 0.5 * tau) ./ (T_in - 0.5 * tau));
sigma = (T_in < 0.5 * tau) ./ (exp(z_exp) + 1);
w = 1 * (T_in <= t_cut) + sigma .* (T_in > t_cut);
plotWindow(w, "Planck-taper", "epsilon = 0.1")
w = 0.35875 - 0.48829*cos(2*pi*k/(N-1)) + 0.14128*cos(4*pi*k/(N-1)) -0.01168*cos(6*pi*k/(N-1));
plotWindow(w, "Blackman-Harris")
w = 0.3635819 - 0.4891775*cos(2*pi*k/(N-1)) + 0.1365995*cos(4*pi*k/(N-1)) -0.0106411*cos(6*pi*k/(N-1));
plotWindow(w, "Blackman-Nuttall")
w = 1 - 1.93*cos(2*pi*k/(N-1)) + 1.29*cos(4*pi*k/(N-1)) -0.388*cos(6*pi*k/(N-1)) +0.032*cos(8*pi*k/(N-1));
plotWindow(w, "Flat top")
tau = (N/2);
w = exp(-abs(k-(N-1)/2)/tau);
plotWindow(w, "Exponential", "tau = N/2", "half window decay")
tau = (N/2)/(60/8.69);
w = exp(-abs(k-(N-1)/2)/tau);
plotWindow(w, "Exponential", "tau = (N/2)/(60/8.69)", "60dB decay")
alpha = 2;
w = 1/2*(1 - cos(2*pi*k/(N-1))).*exp(alpha*abs(N-2*k-1)/(1-N));
plotWindow(w, "Hann-Poisson", "alpha = 2")
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Lähtekood InfoField | Octave
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Selles failis kujutatud üksused
kujutab
Teatud väärtus ilma Vikiandmete üksuseta
17. detsember 2005
source of file inglise
original creation by uploader inglise
media type inglise
image/png
Faili ajalugu
Klõpsa kuupäeva ja kellaaega, et näha sel ajahetkel kasutusel olnud failiversiooni.
Kuupäev/kellaaeg | Pisipilt | Mõõtmed | Kasutaja | Kommentaar | |
---|---|---|---|---|---|
viimane | 9. veebruar 2013, kell 19:48 | 2500 × 1123 (83 KB) | Olli Niemitalo | Antialiasing, layout changes, larger font | |
18. detsember 2005, kell 00:07 | 1038 × 419 (7 KB) | Tiaguito~commonswiki | file size. color source: http://en.wikipedia.org/wiki/Window_Function | ||
17. detsember 2005, kell 23:48 | 1038 × 419 (8 KB) | Tiaguito~commonswiki | source: http://en.wikipedia.org/wiki/Window_Function author: http://en.wikipedia.org/wiki/User:Bob_K |
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Pärit leheküljelt "https://et.wikipedia.org/wiki/Fail:Window_function_(rectangular).png"