In a first image formation mode, an image is formed with a first development contrast C1 and a specific dot pattern is formed with a second development contrast C2, which is lower than the first development contrast C1; in a second image formation mode, an image is formed with a third development contrast C3 and a specific dot pattern is formed with a fourth development contrast C4, which is lower than the third development contrast C3; and when C1 (=C2/C1) denotes a ratio between the second development contrast C2 and the first development contrast C1, and C2 (=C4/C3) denotes a ratio between the fourth development contrast C4 and the third development contrast C3, C2<C1 is satisfied.

An image forming apparatus includes an image forming device which forms an image on a recording medium and an image scanning device which transmits scanned image data to the image forming device. The image forming device includes a receiver, a first image forming unit, a second image forming unit, and a controller. The receiver receives at least one of external image data transmitted from an external device and the scanned image data as input image data. The first image forming unit forms a developer image based on the input image data on the recording medium. The second image forming unit forms a mark image on the recording medium. The controller determines whether to make the second image forming unit form the mark image or not depending on a type of a transmission source of the input image data.

An image forming apparatus includes an image forming device which forms an image on a recording medium and an image scanning device which transmits scanned image data to the image forming device. The image forming device includes a receiver, a first image forming unit, a second image forming unit, and a controller. The receiver receives at least one of external image data transmitted from an external device and the scanned image data as input image data. The first image forming unit forms a developer image based on the input image data on the recording medium. The second image forming unit forms a mark image on the recording medium. The controller determines whether to make the second image forming unit form the mark image or not depending on a type of a transmission source of the input image data.

An image forming apparatus according to the invention includes a plurality of image forming units and a changeover unit. The plurality of image forming units form multicolor images on an image carrier by overlapping, on a medium, developer images developed using developers. The changeover unit changes a layer overlapping sequence of the developer images on the medium. The developers include a developer emitting light according to radiation of non-visible light, and the changeover unit changes the layer overlapping sequence of the developer images using the developer emitting the light according to radiation of the non-visible light.

An image forming apparatus according to the invention includes a plurality of image forming units and a changeover unit. The plurality of image forming units form multicolor images on an image carrier by overlapping, on a medium, developer images developed using developers. The changeover unit changes a layer overlapping sequence of the developer images on the medium. The developers include a developer emitting light according to radiation of non-visible light, and the changeover unit changes the layer overlapping sequence of the developer images using the developer emitting the light according to radiation of the non-visible light.

An image can be formed by using a developer containing a luminescent substance, without impairing the finish of the area in which the image is formed. An image forming device 100 includes a print function section 124 which forms a first image included in a plurality of images to be formed on a single page, based on image formation data indicating the image to be formed, on a medium by using a first developer, and forms a second image included in the plurality of images, based on the image formation data, in a non-image-forming area in which the first image is not formed on the medium, by using a second developer containing a luminescent substance.

An image forming apparatus includes an image forming device which forms an image on a recording medium and an image scanning device which transmits scanned image data to the image forming device. The image forming device includes a receiver, a first image forming unit, a second image forming unit, and a controller. The receiver receives at least one of external image data transmitted from an external device and the scanned image data as input image data. The first image forming unit forms a developer image based on the input image data on the recording medium. The second image forming unit forms a mark image on the recording medium. The controller determines whether to make the second image forming unit form the mark image or not depending on a type of a transmission source of the input image data.

An image forming apparatus includes an image forming device which forms an image on a recording medium and an image scanning device which transmits scanned image data to the image forming device. The image forming device includes a receiver, a first image forming unit, a second image forming unit, and a controller. The receiver receives at least one of external image data transmitted from an external device and the scanned image data as input image data. The first image forming unit forms a developer image based on the input image data on the recording medium. The second image forming unit forms a mark image on the recording medium. The controller determines whether to make the second image forming unit form the mark image or not depending on a type of a transmission source of the input image data.

An electrophotographic printing system includes circuitry configured to: select, in accordance with an operation to an input device, a mask pattern made up of first toner representing black by a combination of a plurality of color toners, the mask pattern being overlaid on an image area of a target image to be concealed within image data; and generate, based on the image data, print data for overlaying and printing the selected mask pattern on the image area.

In accordance with an embodiment, an image forming apparatus comprises a peripheral image acquisition section, a face detection section, a face recognition section and a printing control section. The peripheral image acquisition section acquires an image of the periphery of the image forming apparatus. The face detection section detects a face of person from the image acquired by the peripheral image acquisition section. The face recognition section calculates a matching rate indicating a matching degree of the face of person detected by the face detection section with a face of a user registered in advance. The printing control section executes a processing relating to printing of the image forming apparatus in a plurality of stages corresponding to the matching rates according to the matching rate calculated by the face recognition section and a threshold value of the matching rate.