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.