A method for reproducing an out-of-gamut spot color includes determining a color gamut for a color printer, and specifying a spot color by color coordinates in a three-dimensional color space. A first target color is determined corresponding to a color having a minimum color difference to the specified spot color, and a second target color is determined corresponding to a color on the color gamut surface having a hue value equal to a hue value of the specified spot color. A path is defined on the color gamut surface connecting the first target color and the second target color, wherein a control parameter is used to specify a relative position along the defined path. A control parameter prediction function is provided which computes a predicted control parameter value as a function of color coordinates. The predicted control parameter value is used to determine an aim color for reproducing the spot color.

First relational equations which represent characteristics of respective sample colors are obtained, and for the respective sample colors, prediction values of spectral characteristics of characteristics-acquired gradation values for a prediction target color are obtained using the first relational equations. Difference values between the prediction values and actual measurement values are obtained, and a sample color for which a minimum difference value is obtained is selected as a reference color. A second relational equation that represents characteristics of the reference color is obtained, and a prediction value of spectral characteristics of a prediction target gradation value for the prediction target color is obtained using the second relational equation.

Techniques and systems for sub-pixel grayscale three-dimensional (3D) printing are described. A technique includes mapping a 3D digital model onto a 3D grid of voxels associated with a 3D printer; assigning a first intensity level to first voxels that are fully contained within the model, the first intensity level being sufficient to cure photoactive resin during a curing time; determining, based on geometric information provided by the model, containment degrees for second voxels that are partially contained within the model; assigning second intensity levels to the second voxels based respectively on the containment degrees, the second intensity levels being greater than a third intensity level and lesser than the first intensity level; assigning the third intensity level to third voxels that are outside of the model; and generating one or more graphic files based on the first, second, third voxels, and respectively assigned intensity levels.

A non-transitory computer-readable medium stores computer-readable instructions. The instructions instruct a computer to perform processes including an acquisition step, a determination step, and a display step. The acquisition step includes acquiring a specified color. The determination step includes determining whether a device-independent color based on the specified color is present within a first color gamut based on first print settings of a printer. The display step includes displaying, when it is determined by the determination step that the device-independent color is present within the first color gamut, second print settings of the printer. The second print settings are different from the first print settings and with which the device-independent color is present within a second color gamut that is based on the second print settings.

Source colors are mapped within a mapping segment starting at a preserved gamut boundary color (P.sub.C) and ending at a target gamut boundary color (I.sub.T-C) of the chromaticity plane, corresponding, in a linear 3D color space, to an intersection of the target color gamut (TCG) with a plane of constant luminance and with a mapping plane (MKO) comprising said source color (M), a black point (K) and a white point (O).

Techniques for interactively determining/visualizing the color content of a source image and how the corresponding image data is mapped to device colors are described herein. For example, the color content of a digital image can be converted between different color spaces to identify gamut limitations of an output device (e.g., a printing assembly), discover color(s) that cannot be accurately reproduced, etc. Color space conversions enable the transformation of the color content of the digital image from device-specific colorants to a device-independent representation (and vice versa). In some embodiments, these transformations are facilitated using lookup tables that are implemented in graphical processing unit-resident memory.

The present principles relate to a method and device for gamut mapping from a first color gamut towards a second color gamut. The method comprises, in a plane of constant hue, obtaining a target lightness for a color on the boundary of first gamut with maximum chroma, called first cusp color; and lightness mapping of the color from the first color gamut towards the second color gamut wherein the lightness mapped color is calculated from a parabolic function applied to the color, the parabolic function mapping the first cusp color to a color having the target lightness. According to a particular characteristic, a preserved chroma is also obtained; and in case the chroma of the color is lower than or equal to the preserved chroma, the lightness mapped color is the color, and in case the chroma of the color is higher than the preserved chroma, the lightness mapped color is calculated from the parabolic function applied to the color.

The present principles relate to a method and device for gamut mapping from a first color gamut towards a second color gamut. The method comprises obtaining a preserved key color (prsv_color.sub.K0) and a hue alignment angle (⊖.sub.K0) of the key color (color.sub.K0) for each key color (color.sub.K0) of at least 3 key colors to define a preserved gamut and a rotated gamut; and performing a hue mapping of a current color (color) from the first color gamut towards the second color gamut wherein in case the current color (color) is in a preserved gamut defined by the preserved key color (prsv_color.sub.K0), the hue mapped current color is unchanged, and in case the current color is out of the preserved gamut, the hue mapped current color is calculated from the hue alignment angle (⊖.sub.K0) of two adjacent key colors of the current color (rotated gamut) and from the preserved area.

A content item to be displayed via a display of an electronic device may be associated with a first set of grey values or a set of color values. The electronic device may generate, maintain, or at least have access to one or more mappings that map the set of color values and/or the first set of grey values to a second set of grey values. Based on the one or more mappings, the electronic device may convert a color value of the set of color values or a first grey value of the first set of grey values to a second grey value of the second set of grey values. The content item may then be displayed utilizing the second grey value.

A gamut adjusting method fully expresses a dynamic range of a display gamut to display an image more naturally. With respect to a brightness signal of each primary color of an input image signal, a data translation unit executes a matrix calculation based on a translation matrix for conversion into an image signal for display control. A saturation calculating unit calculates saturation of the input image signal. When saturation is smaller than a threshold value, the data translation unit is set with a translation matrix such that a tone on the display corresponds to or approximates a tone of the input image signal. When saturation is greater than the threshold value and smaller than a maximum value, as the saturation increases, a translation matrix is switched such that a vector on a xy chromaticity diagram toward a tone on a display approximates a vector toward a tone for maximum saturation.