# im.object

##### Class of Images

A class `"im"`

to represent a two-dimensional pixel image.

##### 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`

.

Image objects may be displayed using the methods
`plot.im`

, `image.im`

, `persp.im`

and `contour.im`

. There are also methods
`summary.im`

for summarising an image,
`mean.im`

for calculating the average pixel value, and
`hist.im`

for plotting a histogram of pixel values.
Values of an image may be looked-up using
`lookup.im`

or using the subset operator `[.im`

.
Calculations involving one or more images (for example,
subtracting one image from another) can often be done
easily using `eval.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.

##### See Also

*Documentation reproduced from package spatstat, version 1.9-1, License: GPL version 2 or newer*