im.object
Class of Images
A class "im"
to represent a two-dimensional pixel image.
- Keywords
- spatial
Details
An object of this class represents a two-dimensional pixel image. It specifies
- the dimensions of the rectangular array of pixels
- $x$and$y$coordinates for the pixels
- a numeric value (``grey value'') at each pixel
X
is an object of type im
,
it contains the following elements:
v
matrix of values
dim
dimensions of matrix v
xrange
range of $x$ coordinates of image window
yrange
range of $y$ coordinates of image window
xstep
width of one pixel
ystep
height of one pixel
xcol
vector of $x$ coordinates of centres of pixels
yrow
vector of $y$ coordinates of centres of pixels
}
Users are strongly advised not to manipulate these entries
directly. Objects of class "im"
may be created by the function
im
. They are also returned by the functions
Kmeasure
and
setcov
.
They may be displayed using the methods
image.im
, persp.im
and contour.im
.
Values of an image may be looked-up using
lookup.im
.
Note that the row index of the matrix v
corresponds
to increasing y coordinate, while the column index of m
corresponds to increasing x coordinate. Thus a correct
display of the image would be obtained by transposing, e.g.
image.default(xcol, yrow, t(im))
, if you wanted to do it by hand.
Warnings
The internal representation of images is likely to change in the next release of this package.