Image forming apparatus with an improved security system for prohibiting printing areas

An image forming apparatus, comprising:

• an image acquiring unit configured to acquire a target image;
• a security pattern attaching unit configured to select a security level of a partial area in the target image among plural security levels, and attach a security pattern corresponding to the selected security level to a position corresponding to the partial area
• a security pattern detecting unit configured to (a) try to detect the security pattern in the target image, and (b) detect the security pattern if the target image includes the security pattern;
• and
• a print processing unit configured to (a) determine a security level corresponding to the detected security pattern, (b) perform a mask process of a visibility corresponding to the determined security level for the partial area to which the security pattern has been attached, and (c) cause the printing device to perform printing of the target image for which the mask process has been performed.