field - any text, number, date, time, timestamp, or container field; or any text expression or numeric expression.
width - the width for the thumbnail.
height - the height for the thumbnail.
GetThumbnail(Dog;GetLayoutObjectAttribute("rectangle","width"); GetLayoutObjectAttribute("rectangle","height")) returns an image stored in the Dog field that fits into the dimensions of the Rectangle layout object.
GetThumbnail(Property;GetWidth(Property)/2;GetHeight(Property)/2)returns an image that is 50 percent of the size of the original image in the Property field.