phantom: Creation of a Phantom

Description

This function creates two dimensional phantom data. There are different options, e.g. to generate a big ellipse that represents the head, and several smaller ellipses, that represent pathological areas to be located in the space of the bigger ellipse.

Usage

phantom(n = 257, design = "A", addIm = "none", DebugLevel = "Normal")

Arguments

(integer) Is the number of columns and rows in the generated phantom. It is assumed that the number of columns is equal to the number of rows. Defaults to n=257.

design

(character) design characterizes the phantom data. It is possible to define different ellipses, with different intensities. There are four default-designs, these are design = "A", "B", "C" and "D". To define an own design of the phantom see below to details. Defaults to design = "A".

addIm

(character) Adds an additional image to the phantom. There are six default-designs for addIm. These are addIm="blurred1", "blurred2", "keen1", "keen2", "simple1" and "simple2". The defaults of addIm will be generated with the function partEllipse. If addIm="none", no image will be added to the phantom. A further possibility is a matrix A (addIm=A) with the same size as the phantom (i.e. dim(A)==c(n,n)). Defaults to addIm = "none".

DebugLevel

(character) This parameter controls the level of output. Defaults to DebugLevel="Normal" for a standard level output. Alternative implementations are "Detail" if it is desirable to show almost all output on screen or "HardCore" for no information at all.

Value

Returns a phantom image.

Details

design:

To define an own design of the phantom (e.g. design=P) you have to note the following conditions:

P is a \((n,5)\) or \((n,6)\) matrix, whereas \(n > 0\).
All elements \(x\) of P have to be between -1 and 1.
Each row from P define a ellipse on \([-1,1]^2\), where

[,1]	\(A\)	Is the additive intensity of the corresponding ellipse.
[,2]	\(x_0\)	Is the \(x\)-coordinate of the center of the ellipse.
[,3]	\(y_0\)	Is the \(y\)-coordinate of the center of the ellipse.
[,4]	\(a\)	Is the half length of the horizontal axis.
[,5]	\(b\)	Is the half length of the vertical axis.
[,6]	\(\alpha\)	Is the angle in degree between the \(x\)-axis of the ellipse
		and the \(x\)-axis of the grid. This parameter is optional,
		but the number of columns have to be the same in all rows.

Examples

Run this code

# NOT RUN {
P1 <- phantom()
P2 <- phantom(addIm="blurred1")
PhPa1 <- c(0.5, 0, 0, 0.4, 0.6)
PhPa2 <- matrix( c(0.6, -0.35, 0, 0.4, 0.6,
         0.3,  0.5,  0, 0.2, 0.35), nrow=2, byrow=TRUE )
P3 <- phantom(design=PhPa1)
P4 <- phantom(design=PhPa2)
viewData(list(P1, P2, P3, P4), list("Default Phantom",  
         "addIm='blurred1'", "First new design",
         "Second new design"))
rm(P1,P2,P3,P4,PhPa1,PhPa2)
# }