摘要:
A system is employed to reveal a watermark in a document. A watermark generator is utilized to select the placement and at least one colorant combination of an image and at least one colorant combination for a watermark on a document, where the at least one colorant combination of the image and the watermark form a metameric pair. A printing system receives data from the watermark generator and places the image and the watermark on the document. A decoder comprising a narrow band illumination element is selected or tuned to a wavelength corresponding to the colorant combinations utilized by the printing system to reveal the watermark placed thereon.
摘要:
A system is employed to reveal a watermark in a document. A watermark generator is utilized to select the placement and at least one colorant combination of an image and at least one colorant combination for a watermark on a document, where the at least one colorant combination of the image and the watermark form a metameric pair. A printing system receives data from the watermark generator and places the image and the watermark on the document. A decoder comprising a narrow band illumination element is selected or tuned to a wavelength corresponding to the colorant combinations utilized by the printing system to reveal the watermark placed thereon.
摘要:
Extended colorant sets are used to hide data or provide a watermark in printed images. Extended set colorants are colorants other than, and in addition to, the standard or common subtractive primary colorants: cyan, magenta, yellow and/or black. Where the extended colorant set supports a plurality of colorant recipes for rendering a given color, watermark data is used to select a colorant recipe from the plurality. As the watermark data to be encoded in the image changes state with image position, alternate colorant recipes or colorant selection functions are selected. The image is rendered based on the alternate colorant recipe selections. Watermark information is encoded in the colorant recipe or colorant selection function selection. Use of the extended colorant sets allows information to be encoded even in portions of an image having colors that do not include a neutral component.
摘要:
Extended colorant sets are used to hide data or provide a watermark in printed images. Extended set colorants are colorants other than, and in addition to, the standard or common subtractive primary colorants: cyan, magenta, yellow and/or black. Where the extended colorant set supports a plurality of colorant recipes for rendering a given color, watermark data is used to select a colorant recipe from the plurality. As the watermark data to be encoded in the image changes state with image position, alternate colorant recipes or colorant selection functions are selected. The image is rendered based on the alternate colorant recipe selections. Watermark information is encoded in the colorant recipe or colorant selection function selection. Use of the extended colorant sets allows information to be encoded even in portions of an image having colors that do not include a neutral component.
摘要:
What is disclosed is a decoding method for retrieving information bits encoded in a printed image comprising the steps of first receiving an input electronic image as a scanned version of the printed image. A region of interest in the image is then extracted and, for that region, an amount of K colorant present, denoted KH; is obtained. Further, a color value is generated therefrom and the GCR used for encoding that region is determined using KH and the obtained color value. Encoded information bits are retrieved therefrom based on the determined GCR. The estimated KH is preferably evaluated conditional to a capacity signal KL and a luminance signal L. From the obtained data, values of KH, KL, and L, are derived wherein KH is estimated from a high resolution scan, and KL and L are estimated from a down-scaled image, respectively. The capacity signal KL and the luminance signal L are derived from the obtained color value. Further, the capacity signal, KL is derived by first applying a suitable operator S to reduce the image from scanner resolution to the watermark resolution and then converting the obtained color values to CMY estimates such that KL=min(C,M,Y) Alternatively, K-capacity is derived from the amount, KL, y, comprises first converting the obtained color values to CMY estimates and applying a suitable operator S to reduce the image from scanner resolution to the watermark resolution such that KL=min(S(C),S(M),S(Y)); wherein L is described by a linear combination of scan signals RGB, such that L=k1S(R)+k2S(G)+k3S(B). The value of KH is determined by first converting the obtained color values to CMY estimates. The estimates determine K-colorant amount at each pixel such that: K=min(C,M,Y). A suitable operator S is applied to reduce the image from scanner resolution to the watermark resolution.
摘要:
What is disclosed is a method for digital watermarking in a calibrated printing path and comprises: first receiving a pixel possessing color values from an input image; receiving a plurality of information bits to be encoded at a corresponding pixel in an output image. Then, one of at least two different GCR functions are selected where the selection is based on the state of the received information bits. The number of GCR functions to be selected from is dependent on the number of possible states of the information bits intended to be encoded at each image pixel and preferably equals the number of states of the information bits intended to be encoded at each image pixel such that the GCR spatially varies across the output image. Further, at least two GCR functions are optimized to carry information and information bits intended to be encoded within the output image are represented with a tag. CMYK values are then generated using the selected GCR function and the color values. These CMYK values are assigned to a corresponding pixel in the output image. The information bits to be encoded at a given pixel indicate the type of object to which that pixel belongs, such as: graphics, picture, text, line art, etc. The output image, when printed, exhibits the property that substantially similar colors occurring at different spatial locations in the input image are produced with substantially different CMYK combinations in the print. Preferably, a parameterized function is used for the GCR function and the encoded state sets the parameter of the function. Information bits should be redundantly encoded throughout the output image. Regions that cannot be encoded by GCR information have to be compensated for. A reference mark is applied on the output image to indicate the starting point and order of the information sequence.
摘要:
A system and method for printer control and color balance calibration. The system and method address the image quality problems of print engine instability, low quality of color balance and contouring from the calibration. The method includes defining combinations of colorants, such as inks or toners that will be used to print images, defining a desired response for the combinations that are to be used and, in real time, iteratively printing CMY halftone color patches, measuring the printed patches via an in situ sensor and iteratively performing color-balance calibration based on the measurements, accumulating corrections until the measurements are within a predetermined proximity of the desired response. The calibration is performed on the halftones while they are in a high quantization resolution form.
摘要:
A color transformation method which accounts for colorant interactions includes establishing a plurality of tone reproduction curves (TRCs), for one or more of the color separations forming a digital image. Each TRC accounts for colorant interactions between a primary colorant with which the first color separation is to be rendered and at least one secondary colorant with which at least a second of the plurality of color separations is to be rendered. The TRCs include input values and their corresponding modified input values. In a given TRC, the input values of the second and optionally other color separations are fixed. For a pixel of the digital image having a given input values for the first and second color separation one or more of the TRCs are selected which bound the fixed input value for the second color separation and a modified input value is determined therefrom.
摘要:
An image processing apparatus, program product, and method determine an achievable gamut achievable by the imaging engine or engines for all spatial locations of an output image, or all utilized print engines. A reference gamut is calculated which is any gamut containing the achievable gamut. A gamut mapping is used to map gamuts from the mean gamut to the achievable gamut, and a set of transformations is calculated for each of a set of input colors to a set of target colors selected from colors in the achievable gamut. Values for a received digital image are transformed for each image pixel or clusters of pixels based on the calculated set of transformations. Output images are generated based on the transformed values.
摘要:
Spatially dependent colorant interaction effects are identified and isolated from other aspects of spatially dependent colorant appearance nonuniformities. A decorrelating function for compensating for the identified spatially dependent colorant interaction effects is determined. Spatially dependent single colorant compensating functions for compensating for the other aspects of the spatially dependent colorant appearance nonuniformities may also be determined. Image data is processed through the decorrelating function, thereby generating colorant values that are compensated for spatially dependent colorant interaction effects. Optionally, image data is also processed through the spatially dependent single colorant compensating functions, thereby generating colorant values that are compensated for both aspects of colorant appearance nonuniformities. The two kinds of compensating functions may be determined, calibrated and/or stored at different spatial and temporal frequencies or resolutions. One or both of the compensating functions may be employed to maintain consistency across a plurality of rendering devices (e.g., marking engines).