US 5,130,789 A · Localized image recoloring using ellipsoid boundary function

Abstract

A mechanism for recoloring a color image defines a spatial region within the image (such as the pupil of the eye) a color characteristic of which (e.g. the `red-eye` phenomenon) is to be selectively modified. To determine whether the color of an image sample within a spatial region is to be modified, the value of the chrominance component of each sample within the region is compared with a regularly shaped (e.g. elliptical) chrominance variation discriminator that surrounds a target color of interest (e.g. red, in the case of a `red-eye` correction). The major axis of the ellipse coincides with the saturation direction of the chrominance plane and its minor axis coincides with the hue direction. For each sampling location within the spatial region, the value of the chrominance component is examined to determine whether it falls within the elliptical chrominance discriminator. If the value of the chrominance component falls within the ellipse, it is modified to a destination chrominance value, based upon where the chrominance value of the sampled of interest falls, so as to soften the color at its edges. The luminance component is modified by an offset based upon the difference in the value of the luminance component of the target color and that of the new color. This luminance value difference is weighted in accordance with the product of the previously determined chrominance weighting coefficient and a prescribed relationship between the geometrical location of the luminance component for the sample of interest and the extent of a prescribed range of luminance variation projected from the elliptical discriminator along the luminance axis of the Y,I,Q coordinate system.

Claims46

Dependent claims

A method of controllably modifying a color characteristic of a colored image that has been spatially sampled to obtain a plurality of color-representative data values, each of which is associated with a respective sampling location within said image comprising the steps of:

(a) defining a region within said image whereat a color characteristic may be selectively modified;
(b) forming a visual representation of a color variation characteristic that is bounded by a regular geometric shape, surrounding a target color;
(c) for each sampling location within said region, identifying whether or not the color represented by its associated data value is located within the regular geometrical shape of the color variation characteristic defined in step (b);
and
(d) for a sampling location, the color-representative data value for which has been identified in step (c) as being located within said regular geometrical shape, modifying its identified color-representative data value to a value that is representative of a `destination` color.

2 more elements

A color image processing system comprising:

an image converter for generating a plurality of output signals representative of color characteristics of a plurality of spatial locations within a color image, prescribed color characteristics of which are to be controllably modified;
a digital converter coupled to receive the output signals from said image converter and generating a plurality of digital code signals, respectively representative of the color characteristics of said image at said plurality of spatial locations;
and
a digital signal processor which receives digital codes generated by said digital converter and controllably modifies selected ones of said digital codes so as to effect a modification of a color characteristic of said color image in accordance with a program through which the following steps (a)-(d) are executed:
(a) defining a spatial region within said image whereat a color characteristic may be selectively modified;
(b) forming a visual representation of a color variation characteristic that is bounded by a regular geometric shape, surrounding a target color;
(c) for each sampling location within said spatial region, identifying whether or not the color represented by its associated digital code is located within the regular geometrical shape of the color variation characteristic defined in step (b);
and
(d) for a sampling location, the digital code for which has been identified in step (c) as being representative of a color located within said regular geometrical shape, modifying its identified digital code to a changed digital code which is representative of a `destination` color.

6 more elements

Dependencies are inferred from the claim text.

Localized image recoloring using ellipsoid boundary function

Life of this patent

Localized image recoloring using ellipsoid boundary function

Life of this patent

Abstract

Claims46