Error code using iradon

I keep getting the error message in my script below when using iradon. How would I resolve this error?

I0 = 10^4;
noAngles = 590;
step = 180/noAngles;
theta = step:step:180;
Y = radon(whatisit,theta)/255;
NoisyRMphantom_Proj = -log(NoisyRMphantom_Trans./I0);
FBPnoisyRM = iradon(NoisyRMphantom_Proj,theta,'linear','Ram-Lak',1,751);

%Error using iradon>parse_inputs (line 346) 
%THETA does not match the number of projections.

%Error in iradon (line 119)
%[p,theta,filter,d,interp,N] = parse_inputs(args{:});

[Walter Roberson]

What is size(NoisyRMphantom_Trans) ?

[Ryan]

1017x360

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/images/ref/iradon.html#d123e197034

• If theta is a vector, then specify R as a 2-D matrix in which each column is the Radon transform for one of the angles in theta.

Your theta is a vector, so your input R (first parameter) should be an array that has the same number of columns as theta has entries.

Your theta has 590 entries (noAngles), so your R should have 590 columns. But instead it has 360 columns.

[Ryan]

Hi Walter, I've changed R colums to match. iradon is working now. Thanks so much!