Method and apparatus for ordering and remapping colors in images of real two- and three-dimensional objects

• US 5,473,736 A
• Filed: 04/26/1993
• Issued: 12/05/1995
• Est. Priority Date: 06/08/1992
• Status: Expired due to Fees

• Current Assignee: Chroma Graphics, Inc.
• Original Assignee: Chroma Graphics, Inc.
• Inventors: Young, Fredric S.
• Primary Examiner(s): Herndon, Heather R.
• Assistant Examiner(s): BUCHEL JR, RUDOLPH JOHN
• Application Number:
  US08/053,277
• Time in Patent Office: 953 Days
• Field of Search: 395/131-132, 395/125-127, 358/518-521, 358/515, 345/150
• US Class Current: 345/593
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G06T 9/001 Model-based coding, e.g. wire frame

Abstract

A color palette mapped to an image obtained by any known process is decomposed to separate contrast components from hue/saturation pairs, then only the hue/saturation pairs are remapped to a new set of hue/saturation parameters according to available mapping techniques, including remapping of ordered color sets, into a new ordered set wherein at least a portion of the contrast components are held at fixed values and not altered. By fixing the contrast components, color remapping is constrained to certain symmetric transformations in Munsell color space which preserves features of the source image in the resultant image.

Claims

1. A method for colorizing a specimen image with a source of ordered colors having three image terms, namely a hue term, a saturation term and a value term, said specimen image being separated into an ordered set of image terms, including gray scale or colors expressible in a three-dimensional color space also expressible as image terms, including a hue term, a saturation term and a value term, the method comprising the steps of:

(a) establishing an ordered set of pixel values of said specimen image using a three-dimensional color scale;

thereafter

(b) assigning to each member of said ordered set of pixel values said hue term and said saturation term according to ordering of said ordered set of image terms from said source of ordered colors while holding fixed the value term of said specimen image, thereby to obtain a palette of colors;

(c) mapping said palette to said specimen image, thereby to obtain a colored image comprising a distribution of colors over the specimen image; and

(d) presenting the colored image of the specimen image through an output device for observation.

2. A method for colorizing a specimen image with a palette source of ordered colors, said method comprising the steps of:

(a) ordering said specimen image as pixels into an ordered set of image terms expressible in a three-dimensional color space of hue, saturation and value terms;

(b) storing said ordered set of image terms in an ordered image file;

(c) ordering a palette source of colors into an ordered set of palette terms expressible in a three-dimensional color space of hue, saturation and value terms;

(d) storing said ordered set of palette terms in an ordered palette file;

(e) decomposing each said ordered palette term in said palette file into a hue/saturation pair and a single value term;

(f) replacing each hue/saturation pair term of said ordered image file with a hue/color saturation pair terms from said ordered palette file according to a one-to-one correspondence while olding fixed the value terms thereby to obtain a colored image comprising a distribution of colors; and

(g) presenting the colored image through an output device for observation.

3. The method according to claim 2, wherein the source of ordered colors is ordered by position in Munsell color space.

4. A method for colorizing a specimen image with a palette source of ordered colors, said method comprising the steps of:

(a) ordering said specimen image as pixels into an ordered set of image terms expressible in a three-dimensional color space of hue, saturation and value terms;

(b) storing said ordered set of image terms in an ordered image file;

(c) extracting a palette of colors from a source image;

(d) storing said palette of colors in a palette file;

(e) decomposing each term in said palette file into a hue/saturation pair and a single value parameter;

(d) ordering colors represented by each said hue/saturation pair into an ordered set of palette terms expressible in a two-dimensional trajectory in color space of hue/saturation pair terms;

(e) storing said ordered set of hue/saturation pair terms in an ordered palette file;

(f) replacing hue/saturation pair terms of said ordered image file with hue/saturation pair terms from said ordered palette file according to a one-to-one correspondence while preserving the value term thereby to obtain a colored image comprising a distribution of colors; and

(g) presenting the colored image through an output device for observation.

5. The method according to claim 4, wherein the source of ordered colors is ordered by position in Munsell color space.

6. A method for colorizing a specimen image with a palette source of ordered colors, said method comprising the steps of:

(a) ordering said specimen image as pixels into an ordered set of image terms expressible in a three-dimensional color space of hue, saturation and value terms;

(b) storing said ordered set of image terms in an ordered image file;

(c) ordering a palette source of colors into an ordered set of palette terms expressible in a three-dimensional color space of hue, saturation and value terms;

(d) storing said ordered set of palette terms in an ordered palette file;

(e) decomposing said ordered palette file into sets of a pair of palette terms and a single palette term, said single palette term being said value terms;

(f) replacing two terms of said ordered image file with said pairs of palette terms from said ordered palette file according to a one-to-one correspondence while preserving the value term thereby to obtain a colored image comprising a distribution of colors; and

(g) presenting the colored image through an output device for observation.

7. The method of claim 6, further including the steps, after the replacing step of:

(f1) adding points in color space connecting a first ordered point and a last ordered point of a full range ordered file and rescaling to a preselected number of points relative to a reference color in order to thereby obtain a closed ordered color file; and

(f2) storing said closed ordered color file in a third memory means.

8. The method according to claim 7, further including the step, after step (f1), of:

(f1a) smoothing across adjacent features of the closed ordered color file, said features comprising hue, saturation and value terms in combination.

9. The method according to claim 8, further including the steps, after step (f1a), of;

(f1b) interpolating between ordered points in the closed ordered file thereby to obtain interpolated points; and

(flc) inserting the interpolated points in color order into the closed ordered color file.

10. An apparatus, including a central processing unit, for preparing ordered sets of colors expressible in three image terms, namely hue, saturation and value terms, of a three-dimensional color space from a source of information for use in mapping the information onto an ordered pattern in a lower dimensional image space as a specimen image, such as a two-dimensional physical surface, the apparatus comprising:

(a) means for establishing an ordered set of pixel values of said specimen image using a three-dimensional color scale;

(b) means coupled to said establishing means for assigning to each member of said ordered set of pixel values said hue term and said saturation term of said three image terms according to ordering of said ordered set of image terms from said source of ordered colors while preserving said value term of said specimen image, thereby to obtain a palette;

(c) means coupled to said assigning means for mapping said palette to said specimen image, thereby to obtain a colored image comprising a distribution of colors over the specimen image; and

(d) an output device coupled to said central processing unit for presenting the colored image of the specimen image for observation.