Lineart: Difference between revisions

Revision as of 15:43, 24 October 2024

String art

The sum of the intensities in each direction (a line integral).

$\rho =x\cos \theta +y\sin \theta$

The new image will be

$R(\rho ,\theta )=\int {\it {f(x,y)\delta (\rho -x\cos \theta +y\sin \theta )dxdy}}$

White canvas $R$ with $N$ nails around the circumference and add straight black lines between the nails.

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Starting nail angle $\psi _{1}$ and ending nail angle $\psi _{2}$ . Maximum number of lines is ${n \choose 2}={\frac {N(N-1)}{2}}$
Convert image array to vectors, and make the linear combination: $Ax=b$ . Solve $min_{x}|Ax-b|^{2}$ .
Problems:
- Line darkness; from step function to some other.
- Pseudoinverse gives not binary result. Greedy algorithm.
FFT in part II gives much better results

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Radon transform; density function $\rho (\alpha ,s)$ .
plot sinogram: $\rho (\alpha ,s)$ .
Make linear transform $\rho _{line_{1}}(\alpha ,s)x_{1}+\rho _{line_{2}}(\alpha ,s)x_{2}+\cdots \approx \rho (\alpha ,s)$

@@ Line 34: / Line 34: @@
 * Radon transform;  density function <math>\rho(\alpha,s )</math>.
 * plot sinogram: <math>\rho(\alpha, s)</math>.
-* Make linear transform
+* Make linear transform <math>\rho_{line_1}(\alpha, s) x_1 +\rho_{line_2}(\alpha, s) x_2 + \cdots \approx \rho(\alpha, s)</math>
-<math>\rho_{line_1}(\alpha, s) x_1 +\rho_{line_2}(\alpha, s) x_2 + \cdots \approx \rho(\alpha, s)</math>
 == References ==