Finding size of reconstructed image in iradon in MATLAB -

Finding size of reconstructed image in iradon in MATLAB -

consider next code:

p = phantom(256); theta = 0:1:179; r = radon(p, theta); = iradon(r, theta);

iradon.m calculates size of reconstructed image using

n = 2*floor(size(r,1)/(2*sqrt(2)))

but why formula? gives n approximately equal number of projections divided square root of 2. how give size of image? there improve way find size of image given r , theta?

size(r,1) not give number of projections, projection size. number of projections size(r,2).

the output of radon of size n x m n = size of individual projections , m number of projections. projection size larger image size - imagine taking projection @ 45 degrees, need projection sqrt(2) times big image in order not lose information. iradon doing reverse calculation original image size back.

in practice, perchance because of way matlab has implemented radon, size of reconstructed image larger original image.

matlab