An image communication system including an image processing apparatus and an external device, wherein the image processing apparatus comprises: reading means for reading a document; receiving means for receiving a document reading request from the external device; control means for controlling the reading means to read the document in accordance with the document reading request received by the receiving means; generation means for generating, based on an image of the document read by the reading means and a designation of file format included in the document reading request received by the receiving means, a file in file format corresponding to the designation included in the document reading request; and transmission means for transmitting to the external device the file generated by the generation means, characterised in that the image communication system further comprises: first request means of the external device for transmitting, to the image processing apparatus, a Get-Printer-Attributes Request to inquire about a file format that can be handled by the image processing apparatus, response means of the image processing apparatus for transmitting, to the external device, a Get-Printer-Attributes Response in which information corresponding to a plurality of file formats that can be handled by the image processing apparatus is set, wherein the information includes first description corresponding to a first type of portable document format, PDF, and second description corresponding to a second type of PDF; and second request means of the external device for transmitting to the image processing apparatus the document reading request including a designation of the second type of PDF as the designation of file format, wherein the first description and the second description include MIME content-type information indicating a PDF, and wherein the MIME content-type information of the second description further includes information which enables the external device to identify that the file format corresponds to a PDF whose size is compressed, and wherein the generation means is configured to generate a file of the second type of PDF based on the image of the document read by the reading means by executing image area separation processing on the image of the read document to separate the image into a text section and an image section, binarizing an image in the text section and executing Modified Modified Relative Element Address Designate, MMR, compression on the binarized image, reducing the resolution of the image section, and executing Joint Photographic Experts Group, JPEG, compression on the image section. reading means for reading a document; receiving means for receiving a document reading request from the external device; control means for controlling the reading means to read the document in accordance with the document reading request received by the receiving means; generation means for generating, based on an image of the document read by the reading means and a designation of file format included in the document reading request received by the receiving means, a file in file format corresponding to the designation included in the document reading request; and transmission means for transmitting to the external device the file generated by the generation means, characterised in that the image communication system further comprises: first request means of the external device for transmitting, to the image processing apparatus, a Get-Printer-Attributes Request to inquire about a file format that can be handled by the image processing apparatus, response means of the image processing apparatus for transmitting, to the external device, a Get-Printer-Attributes Response in which information corresponding to a plurality of file formats that can be handled by the image processing apparatus is set, wherein the information includes first description corresponding to a first type of portable document format, PDF, and second description corresponding to a second type of PDF; and second request means of the external device for transmitting to the image processing apparatus the document reading request including a designation of the second type of PDF as the designation of file format, wherein the first description and the second description include MIME content-type information indicating a PDF, and wherein the MIME content-type information of the second description further includes information which enables the external device to identify that the file format corresponds to a PDF whose size is compressed, and wherein the generation means is configured to generate a file of the second type of PDF based on the image of the document read by the reading means by executing image area separation processing on the image of the read document to separate the image into a text section and an image section, binarizing an image in the text section and executing Modified Modified Relative Element Address Designate, MMR, compression on the binarized image, reducing the resolution of the image section, and executing Joint Photographic Experts Group, JPEG, compression on the image section.