A facsimile apparatus contains transfer modes such as a standard mode, a fine image quality mode, a super fine image quality mode which are different from one another in resolution. A signal representing each transfer mode is transmitted from the transmission side to the reception side before the transmission and reception of facsimile image data. A control unit detects the resolution of reception data according to the transfer mode signal to switch over methods for conversion into high-tone in a high-tone conversion unit or to set the magnification of conversion of a resolution conversion unit according to the detected resolution. In this case, when high resolution is detected, the unit for conversion into high-tone executes conversion into multi-value using an area of 17.times.17 picture elements around candidate picture elements for processing. When low resolution is detected, the unit executes the conversion into multi-value using an area of 11.times.11 picture elements around the candidate picture elements for processing.