Image post-processing method and apparatus for emitting a glossiness control light, and image forming apparatus

An image post-processing apparatus comprising:

• a light emitter;
• a heating device;
• and
• a hardware processor which
• causes the light emitter to, to a toner image formed of a toner containing a light absorbing compound and fixed to a recording medium, emit glossiness control light having a maximum emission wavelength in a wavelength range in which the compound absorbs light and made to reduce or increase the glossiness of the toner image, wherein when the glossiness is required to be lowered, the glossiness control light is emitted to the toner image with a first light amount which does not re-melt but softens the toner to reduce the glossiness by increasing irregularity on the surface of the toner image, and when the glossiness is required to be increased, the glossiness control light is emitted to the toner image with a second light amount that is larger than the first light amount which re-melts the toner to increase the glossiness by smoothing the surface of the toner image, and
• causes the heating device to heat the toner image immediately before the glossiness control light is emitted to the toner image such that the toner image has a surface temperature which is at least 20° C. lower than a softening temperature of the toner.

An image forming apparatus comprising:

• a transfer unit which transfers, onto a recording medium, a toner image formed of a toner containing a light absorbing compound;
• a fixing unit which fixes the toner image to the recording medium;
• a light emitter;
• a heating device;
• and
• a hardware processor which
• causes the light emitter to, to the toner image fixed to the recording medium, emit glossiness control light having a maximum emission wavelength in a wavelength range in which the compound absorbs light and made to reduce or increase the glossiness of the toner image, wherein when the glossiness is required to be lowered, the glossiness control light is emitted to the toner image with a first light amount which does not re-melt but softens the toner to reduce the glossiness by increasing irregularity on the surface of the toner image, and when the glossiness is required to be increased, the glossiness control light is emitted to the toner image with a second light amount that is larger than the first light amount which re-melts the toner to increase the glossiness by smoothing the surface of the toner image, and
• causes the heating device to heat the toner image immediately before the glossiness control light is emitted to the toner image such that the toner image has a surface temperature which is at least 20° C. lower than a softening temperature of the toner.