Representing a region of a color image using a space-color separable model
First Claim
1. A method for operating a processor-controlled machine to compute a function representing original color values of original image locations in an image region of a color image;
- the machine including memory for storing data;
the data including image definition data defining an image and instruction data; and
a processor connected for accessing the image definition data, and for accessing the instruction data stored in the memory for operating the machine;
the method comprising;
obtaining a plurality of image region data items indicating image definition data defining an input color image region;
each image region data item indicating coordinate values of a respective original image location in the input color image region and an original color value of the respective original image location;
computing a first function to represent a spatial image structure of the input color image region;
the first function mapping each coordinate value indicating an original image location in the input color image region to a point in a parameter space;
computing a second function to represent a color space subset of a color space structure of the input color image region;
the second function mapping each point in the parameter space to a color space location in the color space subset; and
computing the composition of the first and second functions to produce a third function, referred to as a space-color separable function, for mapping coordinate values of the input color image region to color values in the color space subset;
the space-color separable function approximating the original color values and the original image locations in the input color image region;
the space-color separable function, when used in place of the image region data items to represent the input color image region, producing a rendered color image region substantially similar in appearance to the input color image region.
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Abstract
A representation of a color image region is called a space-color separable (SCS) model because the spatial structure of the image region is represented separately from that of the color-space structure. The representation uses two functions, one to represent the region'"'"'s spatial structure and another to represent its color-space structure. In one implementation, the spatial structure is represented by polynomials of arbitrary degree to map image locations to the parameter values of the color-space model which in turn maps these parameter values to a zero-, one-, two-, or three-dimensional linear subspace of color space. The representation is resolution-independent and can accommodate both transformations of image coordinates and transformation of color coordinates. In particular, the polynomial-linear implementation can easily accommodate both affine transformations of image coordinates and linear transformations of color coordinates. This flexibility makes it useful for a variety of applications in illustration and image editing systems. The invention combines several features: representing smooth shading or textures in color images; separating the spatial structure of the colors in the image from its color space structure; and enabling transformations of images and their colors by transforming the SCS model itself.
91 Citations
15 Claims
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1. A method for operating a processor-controlled machine to compute a function representing original color values of original image locations in an image region of a color image;
- the machine including memory for storing data;
the data including image definition data defining an image and instruction data; and
a processor connected for accessing the image definition data, and for accessing the instruction data stored in the memory for operating the machine;
the method comprising;obtaining a plurality of image region data items indicating image definition data defining an input color image region;
each image region data item indicating coordinate values of a respective original image location in the input color image region and an original color value of the respective original image location;computing a first function to represent a spatial image structure of the input color image region;
the first function mapping each coordinate value indicating an original image location in the input color image region to a point in a parameter space;computing a second function to represent a color space subset of a color space structure of the input color image region;
the second function mapping each point in the parameter space to a color space location in the color space subset; andcomputing the composition of the first and second functions to produce a third function, referred to as a space-color separable function, for mapping coordinate values of the input color image region to color values in the color space subset;
the space-color separable function approximating the original color values and the original image locations in the input color image region;
the space-color separable function, when used in place of the image region data items to represent the input color image region, producing a rendered color image region substantially similar in appearance to the input color image region. - View Dependent Claims (2, 3, 4)
- the machine including memory for storing data;
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5. An article of manufacture for access by a machine that includes a memory device for storing data;
- storage medium access circuitry for accessing a medium that stores data; and
a processor connected for accessing the data stored in the memory device and for receiving data from the storage medium access circuitry;
the article comprising;a data storage medium that can be accessed by the storage medium access circuitry when the article is accessed by the machine; and data stored in the data storage medium so that the storage medium access circuitry can provide the stored data to the processor when the article is accessed by the machine;
the stored data comprising instruction data indicating instructions the processor can execute;the processor, in executing the instructions, obtaining a plurality of image region data items indicating image definition data defining an input color image region;
each image region data item indicating coordinate values of a respective original image location in the input color image region and an original color value of the respective original image location;the processor, further in executing the instructions, computing a first function to represent a spatial image structure of the input color image region;
the first function mapping each coordinate value indicating an original image location in the input color image region to a point in a parameter space;the processor, further in executing the instructions, computing a second function to represent a color space subset of a color space structure of the input color image region;
the second function mapping each point in the parameter space to a color space location in the color space subset; andthe processor, still further in executing the instructions, computing the composition of the first and second functions to produce a third function, referred to as a space-color separable function, for mapping coordinate values of the input color image region to color values in the color space subset;
the space-color separable function approximating the original color values and the original image locations in the input color image region;
the space-color separable function, when used in place of the image region data items to represent colors in the input color image region, producing a rendered color image region substantially similar in appearance to the input color image region. - View Dependent Claims (6, 7, 8, 9, 10)
- storage medium access circuitry for accessing a medium that stores data; and
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11. A data structure stored on a storage medium capable of being accessed and read by a processor-controlled machine;
- the data structure representing an original image;
the machine including storage medium access circuitry for accessing and reading the data structure stored in the storage medium;
the data structure comprising a plurality of region data items;
each region data item representing a respective one of a plurality of image regions in the original image;
each image region formed by a set of image region boundaries determined to be included in the original image;each respective one of the plurality of region data items indicating a space-color separable function representing values of image colors and image locations of a respective image region of the original image represented by the respective region data item; the space-color separable function approximating original color values and original image locations in the respective image region as a composition of a first function and a second function;
the first function representing a spatial image structure of the image region and mapping each coordinate value indicating an original image location in the image region to a point in a parameter space;
the second function representing a color space subset of a color space structure of the image region and mapping each point in the parameter space to a color space location in the color space subset;
the space-color separable function producing a rendered color image region substantially similar in appearance to the respective image region. - View Dependent Claims (12, 13)
- the data structure representing an original image;
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14. In a processor-based system including a memory having instructions stored therein indicating instructions for a color image editing application program the processor executes, and including a display device having a display area wherein an original color image is presented;
- the original color image being represented in memory as an original image definition data structure;
the original color image including a plurality of image regions determined to be included therein;
the improvement wherein the processor, in executing the instructions for performing the color image editing application program, produces, for each respective image region determined to be included in the original color image, a representation of the respective image region as a space-color separable function;
the space-color separable function approximating original color values and original image locations in the respective image region;
the processor, in producing the space-color separable function,obtaining a plurality of image region data items each indicating image definition data defining the respective image region;
each image region data item indicating coordinate values of a respective original image location in the respective image region and an original color value of the respective original image location;computing a first function to represent a spatial image structure of the respective image region;
the first function mapping each coordinate value indicating an original image location in the respective image region to a point in a parameter space;computing a second function to represent a color space subset of a color space structure of the respective image region;
the second function mapping each point in the parameter space to a color space location in the color space subset; andcomputing the composition of the first and second functions to produce the space-color separable function for mapping coordinate values of the respective image region to color values in the color space subset;
the space-color separable function, when used in place of the image region data items to represent the respective image region, producing a rendered color image region substantially similar in appearance to the respective image region. - View Dependent Claims (15)
- the original color image being represented in memory as an original image definition data structure;
Specification