1. A printing apparatus capable of synthesizing and printing image data representing an image to be printed and image data representing a background image, the apparatus comprising: a memory that stores first image data representing a first background image of a first size; a connection unit configured to connect the printing apparatus via a network to a server that stores second image data representing a second background image of a second size that is greater than the first size; an obtaining unit configured to obtain the second image data representing the second background image that is stored in the server, by accessing the server via the network; a setting unit configured to set a condition for printing using the image data representing the image to be printed, the condition including a size of a printing medium used for printing the image represented by the image data; a synthesizing unit configured to in a case where the size of the printing medium included in the condition set by the setting unit is not larger than a predetermined size, synthesize the image data representing the image to be printed and the first image data read from the memory without going through the network, and in a case where the size of the printing medium included in the condition set by the setting unit is larger than the predetermined size, synthesize the image data representing the image to be printed and the second image data obtained by the obtaining unit from the server via the network; and a printing unit configured to print the image data representing the image to be printed that has been synthesized with the first or second image data.