X-Git-Url: http://git.kpe.io/?p=ctsim.git;a=blobdiff_plain;f=doc%2Fctsim-concepts.tex;h=e76a77f6c54cf4f9221c6661bff3466cea0eb572;hp=417c47a90087bffcbcfe86c0872408f83d234e1a;hb=82ea0c94394a5a175b260160760155a6686203a1;hpb=676f8753e1b3edd337240391855f34dde1af24fa diff --git a/doc/ctsim-concepts.tex b/doc/ctsim-concepts.tex index 417c47a..e76a77f 100644 --- a/doc/ctsim-concepts.tex +++ b/doc/ctsim-concepts.tex @@ -11,8 +11,8 @@ user-controlled algorithms producing an image of the phantom object. These reconstructions can be visually and statistically compared to the original phantom object. -In order to use \ctsim\ effectively, some knowledge of how \ctsim\ -works and the approach taken is required. \ctsim\ deals with a +In order to use \ctsim\ effectively, some knowledge of how +\ctsim\ works and the approach taken is required. \ctsim\ deals with a variety of object, but the two primary objects that we need to be concerned with are the \emph{phantom} and the \emph{scanner}. @@ -249,20 +249,21 @@ To illustrate, the \emph{scan diameter} can be defined as \latexonly{\begin{equation}s_d = s_r v_r p_d\end{equation}} \latexignore{\\\centerline{\emph{Sd = Sr x Vr x Pd}}\\} -Further, $f$ can be defined as \latexonly{$$f = f_r (v_r p_d / -2)$$}\latexignore{\\$$F = FR x (VR x Pd)$$\\} +Further, $f$ can be defined as +\latexonly{\[f = f_r (v_r p_d / 2)\]} +\latexignore{\\\centerline{\emph{F = FR x (VR x Pd)$$\\}}} Substituting these equations into \latexignore{the above equation,}\latexonly{equation~\ref{alphacalc},} We have, \latexonly{ \begin{eqnarray} -\alpha &= 2\,\sin^{-1} \frac{s_r v_r p_d / 2}{f_r v_r (p_d / 2)} \nonumber \\ -&= 2\,\sin^{-1} (s_r / f_r) +\alpha &=& 2\,\sin^{-1} \frac{\displaystyle s_r v_r p_d / 2}{\displaystyle f_r v_r (p_d / 2)} \nonumber \\ +&=& 2\,\sin^{-1} (s_r / f_r) \end{eqnarray} } \latexignore{\\\centerline{\emph{\alpha = 2 sin (Sr / Fr)}}\\} Since in normal scanning $s_r$ = 1, $\alpha$ depends only upon the -\emph{focal length ratio}. +\emph{focal length ratio} in normal scanning. \subsubsection{Detector Array Size} In general, you do not need to be concerned with the detector @@ -346,21 +347,23 @@ interpolation can be specified. \section{Image Comparison}\index{Image comparison} Images can be compared statistically. Three measurements can be calculated by \ctsim. They are taken from the standard measurements used by -Herman\cite{HERMAN80}. -$d$ is the normalized root mean squared distance measure, -$r$ is the normalized mean absolute distance measure, -and $e$ is the worst case distance measure over a $2\times2$ area. - -To compare two images, $A$ and $B$, each of which has $n$ columns and $m$ rows, -these values are calculated as below. - - -\latexonly{ -\begin{equation} -d = \sqrt{\frac{\sum_{i=1}^{n}{\sum_{j=1}^{m}{(A_{ij} - B_{ij})^2}}} - {\sum_{i=1}^{n}{\sum_{j=1}^{m}{(A_{ij} - A^{\_})^2}}}} -\end{equation} -\begin{equation} -r = \max(|A_{ij} - B{ij}|) -\end{equation} -} +Herman\cite{HERMAN80}. They are: +\begin{description} +\item[$d$] The normalized root mean squared distance measure. +\item[$r$] The normalized mean absolute distance measure. +\item[$e$] The worst case distance measure over a $2\times2$ area. +\end{description} + +These measurements are defined in equations \ref{dequation} through \ref{bigrequation}. +In these equations, $p$ denotes the phantom image, $r$ denotes the reconstruction +image, and $\bar{p}$ denotes the average pixel value for $p$. Each of the images have a +size of $m \times n$. In equation \ref{eequation} $[n/2]$ and $[m/2]$ denote the largest +integers less than $n/2$ and $m/2$, respectively. + +\latexignore{These formulas are shown in the print documentation of \ctsim.} +\latexonly{\begin{equation}\label{dequation}d = \sqrt{\frac{\displaystyle \sum_{i=1}^{n}{\sum_{j=1}^{m}{(p_{i,j} - r_{i,j})^2}}} {\displaystyle \sum_{i=1}^{n}{\sum_{j=1}^{m}{(p_{i,j} - \bar{p})^2}}}}\end{equation}} +\latexonly{\begin{equation}\label{requation}r = \frac{\displaystyle \sum_{i=1}^{n}{\sum_{j=1}^{m}{|p_{i,j} - r_{i,j}|}}} {\displaystyle \sum_{i=1}^{n}{\sum_{j=1}^{m}{|p_{i,j}|}}}\end{equation}} +\latexonly{\begin{equation}\label{eequation}e = \max_{1 \le k \le [n/2] \atop 1 \le l \le [m/2]}(|P_{k,l} - R_{k,l}|)\end{equation}} +\latexonly{where} +\latexonly{\begin{equation}\label{bigpequation}P_{k,l} = {\textstyle \frac{1}{4}} (p_{2k,2l} + p_{2k+1,2l} + p_{2k,2j+l} + p_{2k+1,2l+1})\end{equation}} +\latexonly{\begin{equation}\label{bigrequation}R_{k,l} = \textstyle \frac{1}{4} (r_{2k,2l} + r_{2k+1,2l} + r_{2k,2l+1} + r_{2k+1,2l+1})\end{equation}}