By default the canvas coincides with image. This function allows you to enlarge or to reduce the canvas size without modifying content of the image.
When you enlarge it you create free space around the image content, which filled with the background color.
When you reduce it, the visible area is cropped. With this command, the pixel information in the image is not changed and the drawing scale is unchanged.
This command affects all the images of the active file or series.
The user can undo this action by use of menu command Undo.
Placement
Set the image content's placement relative to canvas.
Width, Height
You can set the Width and the Height of the new image. Default unit is pixel but you can choose another one, e.g. centimeter. Alternatively you can set the new dimensions relatively to the current dimensions.
Constrain Proportions
With this option checked, the old and the new image will have the same relation of width and height; so changing of one dimension affects the other.
OK button
Accepts the user input, resizes the canvas, and closes this dialog box.
Cancel button
Cancels the procedure of canvas resizing, and closes this dialog box.
Help button
Displays this help topic.
Related Topics
Image Size
Undo