An optical article printed on a substrate may include an organic binder; and a plurality of reflective magnetic platelets provided in the organic binder, wherein the plurality of reflective magnetic platelets are substantially aligned in accordance with at least part of a surface of revolution, and wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis, wherein the first reflective effect is different from the second reflective effect.

An optical article printed on a substrate may include an organic binder; and a plurality of reflective magnetic platelets provided in the organic binder, wherein the plurality of reflective magnetic platelets are substantially aligned in accordance with at least part of a surface of revolution, and wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis, wherein the first reflective effect is different from the second reflective effect.

A first pattern and the second pattern in an original include relatively lighter markings within a relatively darker background. The first pattern differs from the second pattern by including non-printing patches between the relatively lighter markings. When the original is exposed to ultraviolet light, the underlying print media fluoresces in response to the ultraviolet light at the non-printing patches, revealing hidden security printing features. When a scanned image is printed on a second sheet of print media to produce a copy of the original, the copy lacks distinct markings at locations where the relatively lighter markings and the non-printing patches appear in the original because the spacing interval of the relatively lighter markings and the non-printing patches is below the minimum resolution of the scanner. Thus, when the copy is exposed to ultraviolet light, the copy does not fluoresce the ultraviolet light where the non-printing patches appear in the original.

An original document is formed using a first print medium by printing a first and second monochrome patterns with a single colorant to form printed first and second regions including first and second shapes, respectively, which are devoid of the colorant. The second shapes have a smaller size and a higher frequency than the first shapes. The first and/or second regions encode information. The first and second patterns and a fluorescence of the first print medium are selected such that the first and second regions of the original document are indistinguishable to the naked eye, under both normal and ultraviolet illumination but are distinguishable, only under the ultraviolet illumination, in a copy formed by scanning the original document and printing the scanned document on a second print medium with a plurality of colorants, to reveal the encoded information.

An optical article printed on a substrate may include an organic binder; and a plurality of reflective magnetic platelets provided in the organic binder, wherein the plurality of reflective magnetic platelets are substantially aligned in accordance with at least part of a surface of revolution, and wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis, wherein the first reflective effect is different from the second reflective effect.

A redundantly printed security-enhanced document, printing method and system ensure the meaning of the information imparted by variable indicia printed by redundant printing on the document with removable scratch-off coatings. By printing the variable indicia with multiple colors, redundancy and integrity of the intended indicia is achieved. Additionally, inverted color indicia countermeasures to pinprick attacks are also disclosed. The redundantly printed document, methods and systems enhance the overall appearance of the redundantly printed document, and reduce possible consequences resulting from misprinted variable indicia. The resultant printed process color indicia maintains a grayscale equivalent level of a process color greater than or equal to the measured grayscale equivalent level of the substrate surface plus an additional contrast delta of 15%.

An original document is formed using a first print medium by printing a first and second monochrome patterns with a single colorant to form printed first and second regions including first and second shapes, respectively, which are devoid of the colorant. The second shapes have a smaller size and a higher frequency than the first shapes. The first and/or second regions encode information. The first and second patterns and a fluorescence of the first print medium are selected such that the first and second regions of the original document are indistinguishable to the naked eye, under both normal and ultraviolet illumination but are distinguishable, only under the ultraviolet illumination, in a copy formed by scanning the original document and printing the scanned document on a second print medium with a plurality of colorants, to reveal the encoded information.

An image forming apparatus includes an image forming unit and developing containers. The image forming unit includes developing stations to form an image on a print medium with toners, based on input image data. The developing containers contain the toners and are attachable to and detachable from the developing stations. The developing containers include a first developing container containing a first toner and a second developing container containing a second toner having a higher luminescence intensity under invisible light than the first toner. The first toner and the second toner are toners that form an image having a higher luminescence intensity under the invisible light than under visible light. The image forming unit adheres the second toner to the print medium before adhering the first toner when the image forming unit superimposes the first toner and the second toner one atop another on the print medium.

A redundantly printed security-enhanced document, printing method and system ensure the meaning of the information imparted by variable indicia printed by redundant printing on the document with removable scratch-off coatings. By printing the variable indicia with multiple colors, redundancy and integrity of the intended indicia is achieved. Additionally, inverted color indicia countermeasures to pinprick attacks are also disclosed. The redundantly printed document, methods and systems enhance the overall appearance of the redundantly printed document, and reduce possible consequences resulting from misprinted variable indicia. The resultant printed process color indicia maintains a grayscale equivalent level of a process color greater than or equal to the measured grayscale equivalent level of the substrate surface plus an additional contrast delta of 15%.

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.