This disclosure relates to advanced image signal processing technology including encoded signals and digital watermarking. One implementation is directed to a printed object comprising: a white substrate or background comprising a first area; an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising extender white and Green 7 ink, the ink mixture comprising a volume or weight ratio of 97.5% to 99.75% white extender and 2.5%-0.25% Green 7 ink; in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and in which the white substrate or background and the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%. Of course, other implementations, methods, packages, systems and apparatus are described in this patent document.

A multispectral watermark and method for generating the multispectral watermark. A color pattern can be provided, which appears a single color/pattern under a first lighting condition. A watermark can be created based on the color pattern and under a second lighting condition comprising ultraviolet light, while the watermark is viewable with an infrared camera in an infrared spectrum. The watermark can be configured as a multispectral watermark with a metameric pair of inks with one ink of the metameric pair of inks using more CMYK toners that reflect in the infrared spectrum as compared to the other ink among the metameric pair of inks while simultaneously allowing more of the ultraviolet light or less of the ultraviolet light to reach a fluorescing media upon which the multispectral watermark is rendered.

A multispectral watermark and method for generating the multispectral watermark. A color pattern can be provided, which appears a single color/pattern under a first lighting condition. A watermark can be created based on the color pattern and under a second lighting condition comprising ultraviolet light, while the watermark is viewable with an infrared camera in an infrared spectrum. The watermark can be configured as a multispectral watermark with a metameric pair of inks with one ink of the metameric pair of inks using more CMYK toners that reflect in the infrared spectrum as compared to the other ink among the metameric pair of inks while simultaneously allowing more of the ultraviolet light or less of the ultraviolet light to reach a fluorescing media upon which the multispectral watermark is rendered.

An image processing method includes: a first obtaining step of obtaining data of an image; a second obtaining step of obtaining additional information; a third obtaining step of obtaining information related to a printable area of a print medium on which the image based on the data obtained in the first obtaining step is printed; determining step of determining a position where the obtained additional information is embedded in the image on the basis of the information obtained in the third obtaining step; and embedding step of embedding the additional information with reference to the determined position.

A system and method are provided for constructing an optical device having a substrate and a filter layer provided on the substrate. The filter layer includes features that render a first image and gaps between the features. An image layer is provided on the filter layer and includes image elements provided within the gaps between the features. The first image is rendered in reflected light and the second image is rendered in transmitted light. According to one example, a second filter layer may be provided on a second side of the substrate such that features of the filter layer and second features of the second filter layer may be at least partially out of vertical alignment in order to define a plurality of light ray entry angles.

A system and method are provided for constructing an optical device having a substrate and a filter layer provided on the substrate. The filter layer includes features that render a first image and gaps between the features. An image layer is provided on the filter layer and includes image elements provided within the gaps between the features. The first image is rendered in reflected light and the second image is rendered in transmitted light. According to one example, a second filter layer may be provided on a second side of the substrate such that features of the filter layer and second features of the second filter layer may be at least partially out of vertical alignment in order to define a plurality of light ray entry angles.

A method for printing a wet web material comprising microfibrillated cellulose, wherein said method comprises the steps of providing an aqueous suspension comprising microfibrillated cellulose; applying said aqueous suspension to a substrate, thus forming a wet web having a moisture content in the range of 5 to 70 weight-%; wherein the method further comprises the step of treating said wet web by heating at least one well-defined portion thereof, whereby the web is provided with a print at the at least one heated portion.

In one or more embodiments, a control unit reads image data and date information of a main image from a memory card into a RAM. When a watermark printing is set, the control unit combines characters of the date information having a high gradation value with overcoat layer data having a mixture pattern in which pixels having a high gradation value and pixels having a low gradation value are located randomly or alternately in rows and columns to generate overcoat layer print data and stores the data in an overcoat layer data storage area. The control unit generates CMY print data from the image data of the main image to print it on image-receiving paper by using a print processing section. After printing of the main image, the control unit prints the overcoat layer print data so that it is superimposed on the main image on the image-receiving paper.

In one or more embodiments, a control unit reads image data and date information of a main image from a memory card into a RAM. When a watermark printing is set, the control unit combines characters of the date information having a high gradation value with overcoat layer data having a mixture pattern in which pixels having a high gradation value and pixels having a low gradation value are located randomly or alternately in rows and columns to generate overcoat layer print data and stores the data in an overcoat layer data storage area. The control unit generates CMY print data from the image data of the main image to print it on image-receiving paper by using a print processing section. After printing of the main image, the control unit prints the overcoat layer print data so that it is superimposed on the main image on the image-receiving paper.

The application discloses apparatus and systems for authenticating physical object, identification documents and security documents. Some such methods and apparatus involve signal encoding or digital watermarking.