If the ‘Create Faxable image’ check is selected the driver to automatically create images that have fax paper size and resolution. The user can select the final resolution of the faxable image between 204x98 DPI (Standard Fax Resolution) and 204x196 DPI (Fine Fax Resolution).
This check box can be used to set the driver to automatically create images that have fax paper size and resolution. The paper sizes and graphic resolutions are not restricted, but the end result image file will have a fax-able page size and fax-compatible resolution. For example, if the page is Letter paper size and 600 DPI, the generated file width will be 1728 pixels.
Many people confuse the US Letter or European A4 paper sizes with fax paper size. According to the ITU T.30 standard, the Fax page width is 215 mm or 1728 pixels, which is slightly different than the US Letter or A4 paper size. There are additional fax paper sizes such as 255 mm and 303 mm; however they are in not in use or there are very limited devices supporting them. If the 255mm or 303 mm paper size is needed, please use the “VARIABLE paper size” setting.