The present disclosure provides a method and system for large-capacity image steganography and recovery based on an invertible neural networks. The method is intended to embed one or more hidden images into a single host image, and recover all the hidden images from a stego image. The method designs an image steganography model that supports bidirectional mapping. The model includes cascaded invertible modules containing a host branch and a hidden branch. A hidden image is embedded into a host image through forward mapping to form a stego image, and the host image and the hidden image are separated and recovered from the single stego image through reverse mapping.

An image forming apparatus includes a first printer configured to print on a medium using a first material, a second printer configured to print on the medium using a second material that turns invisible when a first condition is satisfied, and a controller configured to: control the first printer to print on the medium a first symbol that is machine-readable and associated with first information, and control the second printer to print a second symbol on the medium on which the first symbol has been printed. A composite symbol of the first and second symbols is machine-readable and associated with second information different from the first information.

A computer-implemented method, system and computer program is disclosed. The method may comprise providing an image comprising a plurality of pixels, identifying at least one portion of the image to be obfuscated, modifying pixels of the at least one image portion using a key for producing an updated image in which the at least one image portion is obfuscated, providing the key, or a link to the key, in an access profile for the identified at least one image portion and allocating permissions to one or more users for enabling them to view the at least one image portion, by use of the key, when viewing the updated image.

A security apparatus and a method for rendering a security mark can involve creating a security mark that includes a correlation mark having a correlation effect and comprising black pixels and white pixels, and subjecting the security mark to a filter that can removes at least some of the black pixels or the white pixels so that the correlation effect no longer functions and the security mark is not visible when rendered on a recording medium.

A security apparatus, method and system for rendering a security mark, can involve providing a security mark with a metameric pair of infrared inks. A spectral reflectance of two metameric inks among the metameric pair of inks differs for CMYK for K in infrared. A first metameric ink among the metameric pair of infrared inks can be configured to include more K than a second metameric ink among the metameric pair of infrared inks, wherein when a document containing the security mark is scanned, and the number of K pixels in the first metameric ink is filtered to destroy the security mark when viewed through an infrared camera.

An image forming apparatus includes a first printer configured to print on a medium using a first material, a second printer configured to print on the medium using a second material that turns invisible when a first condition is satisfied, and a controller configured to: control the first printer to print on the medium a first symbol that is machine-readable and associated with first information, and control the second printer to print a second symbol on the medium on which the first symbol has been printed. A composite symbol of the first and second symbols is machine-readable and associated with second information different from the first information.

A method and system for hiding reversible data based on prediction errors are provided, where the method includes: partitioning an image, to obtain a shadow part and a blank part; performing a first-layer embedding process on the shadow part; performing a multi-layer embedding process on the blank part; extracting outermost layer information of the blank part after the multilayer embedding process; and extracting information of the shadow part after the first-layer embedding process. According to the method in the present disclosure, a problem of image distortion during high-capacity data embedding can be effectively solved.

A device includes a processor and associated memory; and a compressor for compressing data representing an electronic document, the electronic document comprising a number of objects. The compressor is to determine for each object of the document whether data of that object is to be compressed with lossy or lossless compression and to compress the data accordingly to generate a compressed electronic document.

An image forming apparatus includes a first printer configured to print on a medium using a first material, a second printer configured to print on the medium using a second material that turns invisible when a first condition is satisfied, and a controller configured to: control the first printer to print on the medium a first symbol that is machine-readable and associated with first information, and control the second printer to print a second symbol on the medium on which the first symbol has been printed. A composite symbol of the first and second symbols is machine-readable and associated with second information different from the first information.

A security apparatus, method and system for rendering a security mark, can involve providing a security mark with a metameric pair of infrared inks. A spectral reflectance of two metameric inks among the metameric pair of inks differs for CMYK for K in infrared. A first metameric ink among the metameric pair of infrared inks can be configured to include more K than a second metameric ink among the metameric pair of infrared inks, wherein when a document containing the security mark is scanned, and the number of K pixels in the first metameric ink is filtered to destroy the security mark when viewed through an infrared camera.