Image processing device and non-transitory recording medium including setting of a prohibition period that prohibits reception of a different synchronization signal

An image processing system comprising:

• an image reading device that reads a physical image to generate an input image signal and to output the input image signal and a synchronization signal;
• at least one processor programmed to function as:
• a reception unit that receives the input image signal and the synchronization signal, the synchronization signal used to generate an output image signal on a basis of the input image signal;
• and
• a setting unit that sets, after the reception unit receives the synchronization signal, a reception prohibition period that prohibits reception of a different synchronization signal by the reception unit, the reception prohibition period being a mask period that is set for each of a plurality of colors after the reception unit receives the synchronization signal, wherein
• the output image signal is a signal generated on a basis of input image signals for the plurality of colors,
• the reception unit receives the input image signal expressing a respective color from among the plurality of colors, and the synchronization signal for each color,
• the synchronization signal is a signal used to generate the output image signal by combining the input image signals for each of the colors, and
• the setting unit sets the reception prohibition period for each color.