Methods and systems for color gamut adjustment

• US 7,742,206 B2
• Filed: 02/08/2005
• Issued: 06/22/2010
• Est. Priority Date: 02/08/2005
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chang, James Z., Dalrymple, John C.
• Primary Examiner(s): Haskins; Twyler L
• Assistant Examiner(s): Yip; Kent
• Application Number:
  US11/053,370
• Publication Number:
  US 20060176528A1
• Time in Patent Office: 1,960 Days
• Field of Search: 358/1.1, 358/1.9, 358/2.1, 358/518, 358/520, 358/522, 358/523, 358/525
• US Class Current: 358/518
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

Embodiments of the present invention comprise methods and systems for color gamut mapping. Some embodiments comprise mapping by projecting a first gamut color point to an intermediate curvilinear construct and then projecting from the curvilinear construct to a second color gamut point. In some embodiments, gamut points are separated into regions with differing projection rules and curvilinear constructs.

Claims

1. A method for color gamut adjustment, said method comprising:

a) determining a plurality of gamut points in a color space, wherein said gamut points represent the limits of a color-rendering capability of an output device;

b) representing at least a portion of said gamut points with at least one curvilinear shape that defines a hue leaf boundary limit;

c) selecting a black point from among said gamut points that represents black;

d) selecting a white point from among said gamut points that represents white;

e) selecting an intermediate point from among said gamut points, wherein said intermediate point divides said gamut points into a first group and a second group;

f) modeling said first group of gamut points with a first curvilinear construct comprising shapes that are mathematically simpler than said at least one curvilinear shape used to represent corresponding points in said hue leaf boundary limit;

g) modeling said second group of gamut points with a second curvilinear construct, comprising shapes that are mathematically simpler than said at least one curvilinear shape used to represent corresponding points in said hue leaf boundary limit;

h) establishing a white point regional boundary line commencing at said white point and projecting perpendicularly outwardly relative to said first construct at said white point;

i) establishing a first intermediate point regional boundary line commencing at said intermediate point and projecting perpendicularly outwardly relative to said first construct at said intermediate point;

j) establishing a second intermediate point regional boundary line commencing at said intermediate point and projecting perpendicularly outwardly relative to said second construct at said intermediate point;

k) establishing a black point regional boundary line commencing at said black point and projecting perpendicularly outwardly relative to said second construct at said black point; and

l) mapping from an input device, colors that fall outside said hue leaf boundary limit to colors within said hue leaf boundary limit of the output device by a method comprising;

i) mapping colors in a white region, defined as the area between said white point boundary and a projection of an axis running between said black point and said white point, to the white point;

ii) mapping colors in a black region, defined as the area between said black point boundary and a projection of an axis running between said black point and said white point, to the black point;

iii) mapping colors in a first region, defined as the area lying between said white point regional boundary and said first intermediate point regional boundary, wherein a point representing a color is projected onto said first construct thereby defining an initial projection point, and projecting said initial projection point onto a part of said hue leaf boundary limit that corresponds to said first group of gamut points;

iv) mapping colors in a second region, defined as the area lying between said first intermediate point regional boundary and said second intermediate point regional boundary, wherein any color in this region is mapped to said intermediate point; and

v) mapping colors in a third region, defined as the area lying between said second intermediate point regional boundary and said black point regional boundary, wherein a point representing a color is projected onto said second construct thereby defining an initial projection point, and projecting said initial projection point onto a part of said hue leaf boundary limit that corresponds to said second group of gamut points.