Code not displaying figure
I was told to implement this code form a texbok, but it isn’t displaying figure like in textbook. Last lines separated by enter has display figure part
I prefer to keep it together as one code. I am very new to matlab.
close all
%image parameters
W = 400;
H = 400;
% object parameters
rho = 200;
A = 0.4;
B = 0.2;
alpha = pi /10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
function [P] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo)
gamma = atan2(yo, xo);
d = sqrt( xo * xo + yo * yo);
thetanew = theta – alpha;
snew = s – d * cos(gamma – theta);
% use translated/rotated values
s = snew;
theta = thetanew;
% find a^2 (theta)
ct = cos(theta);
st = sin(theta);
a2 = A*A*ct*ct + B*B*st*st;
atheta = sqrt(a2);
% return value if outside ellipse
P = 0;
if( abs(s) <= atheta )
% inside ellipse
P = 2 * rho * A * B / a2 * sqrt(a2 – s * s);
end
end %added
function [projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo)
thetamin = 0;
thetamax = pi;
% each row is a projection at a certain angle
projmat = zeros(ntheta, ns);
smin = -srange;
smax = srange;
dtheta = pi/(ntheta – 1);
ds = (smax – smin)/(ns – 1);
svals = smin:ds:smax;
thetavals = thetamin:dtheta:thetamax;
pn = 1;
for theta = thetavals
% calculate all points on the projection line
P = zeros(ns, 1);
ip = 1;
for s = svals
% simple ellipse
[p] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo);
P(ip) = p;
ip = ip + 1;
end
% save projection as one row of matrix
projmat(pn, 🙂 = P’;
pn = pn + 1;
end
end %added
function [b] = bpsolve(W, H, projmat, svals, thetavals)
ntheta = length(thetavals);
ns = length(svals);
srange = svals(ns);
b = zeros(H, W);
for iy = 1:H
for ix = 1:W
x = 2 * (ix – 1)/(W – 1) – 1;
y = 1 – 2 * (iy – 1)/(H – 1);
% projmat is the P values, each row is P(s) for a given theta
bsum = 0;
for itheta = 1:ntheta
theta = thetavals(itheta);
s =x*cos(theta) + y*sin(theta);
is = (s + srange)/(srange*2)*(ns – 1) + 1;
is = round(is);
if(is < 1)
is = 1;
end
if(is > ns)
is = ns;
end
Ptheta = projmat(itheta, is);
bsum = bsum + Ptheta;
end
b(iy, ix) = bsum;
end
end
% image parameters
W = 400;
H = 400;
% object parameters
% rho = 200;
A = 0.4;
B = 0.2;
alpha = pi/10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
% generate projections
[projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo); % solve using backprojection
[b] = bpsolve(W, H, projmat, svals, thetavals);
% scale for image display
b = b/max(max(b)); b = b*255;
bi = uint8(b);
figure(1);
clf
image(bi);
colormap(gray(256));
box(‘on’);
axis(‘off’);
shg;
saveas(gcf,’CompileData.png’);
end %addedI was told to implement this code form a texbok, but it isn’t displaying figure like in textbook. Last lines separated by enter has display figure part
I prefer to keep it together as one code. I am very new to matlab.
close all
%image parameters
W = 400;
H = 400;
% object parameters
rho = 200;
A = 0.4;
B = 0.2;
alpha = pi /10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
function [P] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo)
gamma = atan2(yo, xo);
d = sqrt( xo * xo + yo * yo);
thetanew = theta – alpha;
snew = s – d * cos(gamma – theta);
% use translated/rotated values
s = snew;
theta = thetanew;
% find a^2 (theta)
ct = cos(theta);
st = sin(theta);
a2 = A*A*ct*ct + B*B*st*st;
atheta = sqrt(a2);
% return value if outside ellipse
P = 0;
if( abs(s) <= atheta )
% inside ellipse
P = 2 * rho * A * B / a2 * sqrt(a2 – s * s);
end
end %added
function [projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo)
thetamin = 0;
thetamax = pi;
% each row is a projection at a certain angle
projmat = zeros(ntheta, ns);
smin = -srange;
smax = srange;
dtheta = pi/(ntheta – 1);
ds = (smax – smin)/(ns – 1);
svals = smin:ds:smax;
thetavals = thetamin:dtheta:thetamax;
pn = 1;
for theta = thetavals
% calculate all points on the projection line
P = zeros(ns, 1);
ip = 1;
for s = svals
% simple ellipse
[p] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo);
P(ip) = p;
ip = ip + 1;
end
% save projection as one row of matrix
projmat(pn, 🙂 = P’;
pn = pn + 1;
end
end %added
function [b] = bpsolve(W, H, projmat, svals, thetavals)
ntheta = length(thetavals);
ns = length(svals);
srange = svals(ns);
b = zeros(H, W);
for iy = 1:H
for ix = 1:W
x = 2 * (ix – 1)/(W – 1) – 1;
y = 1 – 2 * (iy – 1)/(H – 1);
% projmat is the P values, each row is P(s) for a given theta
bsum = 0;
for itheta = 1:ntheta
theta = thetavals(itheta);
s =x*cos(theta) + y*sin(theta);
is = (s + srange)/(srange*2)*(ns – 1) + 1;
is = round(is);
if(is < 1)
is = 1;
end
if(is > ns)
is = ns;
end
Ptheta = projmat(itheta, is);
bsum = bsum + Ptheta;
end
b(iy, ix) = bsum;
end
end
% image parameters
W = 400;
H = 400;
% object parameters
% rho = 200;
A = 0.4;
B = 0.2;
alpha = pi/10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
% generate projections
[projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo); % solve using backprojection
[b] = bpsolve(W, H, projmat, svals, thetavals);
% scale for image display
b = b/max(max(b)); b = b*255;
bi = uint8(b);
figure(1);
clf
image(bi);
colormap(gray(256));
box(‘on’);
axis(‘off’);
shg;
saveas(gcf,’CompileData.png’);
end %added I was told to implement this code form a texbok, but it isn’t displaying figure like in textbook. Last lines separated by enter has display figure part
I prefer to keep it together as one code. I am very new to matlab.
close all
%image parameters
W = 400;
H = 400;
% object parameters
rho = 200;
A = 0.4;
B = 0.2;
alpha = pi /10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
function [P] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo)
gamma = atan2(yo, xo);
d = sqrt( xo * xo + yo * yo);
thetanew = theta – alpha;
snew = s – d * cos(gamma – theta);
% use translated/rotated values
s = snew;
theta = thetanew;
% find a^2 (theta)
ct = cos(theta);
st = sin(theta);
a2 = A*A*ct*ct + B*B*st*st;
atheta = sqrt(a2);
% return value if outside ellipse
P = 0;
if( abs(s) <= atheta )
% inside ellipse
P = 2 * rho * A * B / a2 * sqrt(a2 – s * s);
end
end %added
function [projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo)
thetamin = 0;
thetamax = pi;
% each row is a projection at a certain angle
projmat = zeros(ntheta, ns);
smin = -srange;
smax = srange;
dtheta = pi/(ntheta – 1);
ds = (smax – smin)/(ns – 1);
svals = smin:ds:smax;
thetavals = thetamin:dtheta:thetamax;
pn = 1;
for theta = thetavals
% calculate all points on the projection line
P = zeros(ns, 1);
ip = 1;
for s = svals
% simple ellipse
[p] = ellipseproj(A, B, rho, theta, s, alpha, xo, yo);
P(ip) = p;
ip = ip + 1;
end
% save projection as one row of matrix
projmat(pn, 🙂 = P’;
pn = pn + 1;
end
end %added
function [b] = bpsolve(W, H, projmat, svals, thetavals)
ntheta = length(thetavals);
ns = length(svals);
srange = svals(ns);
b = zeros(H, W);
for iy = 1:H
for ix = 1:W
x = 2 * (ix – 1)/(W – 1) – 1;
y = 1 – 2 * (iy – 1)/(H – 1);
% projmat is the P values, each row is P(s) for a given theta
bsum = 0;
for itheta = 1:ntheta
theta = thetavals(itheta);
s =x*cos(theta) + y*sin(theta);
is = (s + srange)/(srange*2)*(ns – 1) + 1;
is = round(is);
if(is < 1)
is = 1;
end
if(is > ns)
is = ns;
end
Ptheta = projmat(itheta, is);
bsum = bsum + Ptheta;
end
b(iy, ix) = bsum;
end
end
% image parameters
W = 400;
H = 400;
% object parameters
% rho = 200;
A = 0.4;
B = 0.2;
alpha = pi/10;
xo = 0.3;
yo = 0.5;
% backprojection parameters
ntheta = 100;
srange = 2;
ns = 100;
% generate projections
[projmat, svals, thetavals] = …
ellipseprojmat(A, B, ntheta, ns, srange, rho, alpha, xo, yo); % solve using backprojection
[b] = bpsolve(W, H, projmat, svals, thetavals);
% scale for image display
b = b/max(max(b)); b = b*255;
bi = uint8(b);
figure(1);
clf
image(bi);
colormap(gray(256));
box(‘on’);
axis(‘off’);
shg;
saveas(gcf,’CompileData.png’);
end %added figure MATLAB Answers — New Questions
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