The canvas is the visible area of the image. By default the canvas
coincides with layers. This function allows you to enlarge or to reduce
the canvas size without modifying content of the layers the image
contains. When you enlarge it you create free space around the image
content. When you reduce it, the visible area is cropped, however the
layers still extend beyond the canvas border.
9.13.1.
Activate Dialog
You can find this command in the Toolbox menu:
Image → Canvas Size
9.13.2.
Options
Figure 10.57.
Dialog canvas size
Canvas Size
Width; Height
You can set the Width and the
Height you want give to the canvas. Default
unit is pixel but you can choose another one, e.g. percents, if
you want set new dimensions relatively to the current
dimensions. If the adjacent Chain is intact both axis will
develop jointly. If you break it by clicking on it, then you can
set every axis separately.
Whatever unit you use, there is always information about the
matching size in pixels and currently set resolution below the
Width and Height fields.
You cannot change the resolution in this dialog, if you want to
do it,use the Print Size
dialog.
Offset
Offset is used to place the image on canvas. The preview displays the
image as a frame with a thin border and the canvas, when it is smaller
than the image, as a frame with a thin black border.
X; Y
X and Y parameters are the coordinates of the upper left corner of
the image against the same corner of the canvas. They are negative
when canvas is smaller than image. You can change them thanks to
the text boxes. Default unit is pixel but you can choose another
one. When the mouse pointer is in a box you can use the Up and
Down arrow keys to change pixel value one by one. When Shift is
pressed in change is ten by ten.
Center
The Center button allows you to place the
image center onto the canvas center.
Note
When you click on the Resize,
the canvas is resized, but the pixel information in the image is not
changed and the drawing scale is unchanged.
Because the added part of canvas doesn't contain layers (if layers
hadn't been extending beyond the canvas border before the change), it
is transparent with a checker look and is not immediately available
for painting. You can either
flatten
the image, in which case you will get an image with a single layer
fitting the canvas exactly, or you can use
Layer to Image Size
command resize the active layer only, without changing any other
layers. You can also create a new layer and fill it with the
background you want. You create so a digital passe-partout (a
passe-partout is a kind of glass mount whose bottom can be opened
so that you can slip a photo into it).
![[Note]](../images/note.png)