method and apparatus for converting from a source color space to a target color space

• US 7,598,961 B2
• Filed: 10/21/2003
• Issued: 10/06/2009
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Higgins, Michael Francis
• Primary Examiner(s): Tung; Kee M
• Assistant Examiner(s): AMIN, JWALANT B
• Application Number:
  US10/691,396
• Publication Number:
  US 20050083352A1
• Time in Patent Office: 2,177 Days
• Field of Search: 345589-591, 345/604, 345/690
• US Class Current: 345/589
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/54 Conversion of colour picture signals to a plurality of signals some of which represent particular mixed colours, e.g. for textile printing
• CPC Class Codes: H04N 1/6022 Generating a fourth subtractive colour signal, e.g. under colour removal, black masking
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85

Abstract

Systems and methods are disclosed to effect a multiple mode display system that may accept multiple input image data formats and output several possible image data formats. One method is disclosed for converting from a source color space to a target color space. The source color space results from a combination of N primary color points and the target color space resulting from combination of a N+1 or more primary color points in the target color space, wherein N is an integer.

Claims

1. A machine-implemented method that defines an image displayed by a display device having M color sources each respectively outputting a respective one of M unique primary colors, where the display device thereby has a displayable color space that is definable as a polygon disposed within a rectangular gamut space where the displayable color space has M>

N primary color points defining vertices of the polygon such that substantially any color point on linear boundaries of the polygon or in an interior of the polygon can be displayed by the M color sources of the display device, where M and N are each a whole number greater than 2 and N defines primary colors of a source color space from which sourced color points are to be rendered by use of the M>

N color sources of the display device, said machine-implemented method converting the sourced color points into target color data signals that define said image displayed by the display device and said method comprising;

(a) first identifying for each sourced color point, a corresponding one of a plurality of hypothetical triangular regions as the region inside of which, or on whose boundaries the sourced color point lies, where said hypothetical triangular regions populate the displayable color space polygon and each of the hypothetical regions has a first vertex at a predefined and common interior point inside the polygon and each hypothetical region respectively has two spaced apart points on the boundary of the polygon as respective second and third vertices of the triangular region;

(b) in response to said first identifying, second identifying a corresponding one of a prespecified plurality of conversion matrices that respectively correspond to the plurality of hypothetical regions, where the identified conversion matrix corresponds to the first identified hypothetical triangular region; and

(c) using the identified conversion matrix to convert the sourced color point into a corresponding target color data signal that defines said image displayed by the display device.

2. The machine-implemented method of claim 1 wherein said hypothetical triangular regions do not overlap with one another.

3. The machine-implemented method of claim 1 wherein said respective second and third vertices of the respective hypothetical triangular regions are defined by vertices of the polygon.

4. The method of claim 1 wherein said machine-implemented first identifying step (a) includes:

determining a hue angle for each sourced color point and using the determined hue angle to identify the corresponding one of the plurality of hypothetical triangular regions.

5. The method of claim 4 wherein said machine-implemented second identifying step (b) includes:

coupling a hue indicating signal to selection terminals of a plurality of multiplexers where selective inputs of the multiplexers receive input signals representing different conversion matrices applied to the sourced color points.

6. The method of claim 1 wherein said common interior point is the white point of the displayable color space.

7. The method of claim 1 wherein said common interior point is an off-white color point of the of the displayable color space.

8. The method of claim 1 wherein said M unique primary colors include a red, a blue, a green, and a cyan.

9. A display system comprising:

(a) a display having M unique color sources each respectively outputting a respective one of M unique primary colors, where the display thereby has a displayable color space that is definable as a polygon disposed within a rectangular gamut space where the displayable color space has M>

N primary color points defining vertices of the polygon such that substantially any color point on linear boundaries of the polygon or in an interior of the polygon can be displayed by the M color sources of the display, where M and N are each a whole number greater than 2 and N defines primary colors of a source color space from which first sourced color points are to be rendered by use of the M>

N color sources of the display device;

(b) a first identifier which identifies each of the first sourced color point as corresponding to one of a plurality of hypothetical radial regions by virtue of the first sourced color point being inside the radial region or on a boundary of the radial region, where said hypothetical radial regions populate the displayable color space polygon and each of the hypothetical radial regions has a first boundary point defining a vertex of the radial region, the first boundary point being disposed at a predefined and common interior point inside the polygon from which the radial region radially expands outwardly at least to the boundary of the polygon and where each hypothetical radial region respectively has two spaced apart boundary points disposed on the boundary of the polygon;

(c) a second identifier which is responsive to the first identifier and identifies a corresponding one of a prespecified plurality of conversion matrices that respectively correspond to the plurality of hypothetical radial regions, where the identified conversion matrix corresponds to the hypothetical radial region identified by the first identifier; and

(d) a signal converter which uses the identified conversion matrix to convert each first sourced color point into a corresponding target color data signal.

10. The display system of claim 9 wherein said hypothetical radial regions do not overlap with one another.

11. The display system of claim 9 wherein said respective second and third boundary points of the respective hypothetical radial region are defined by vertices of the polygon.

12. The display system of claim 9 wherein each radial region is a triangle, wherein said respective second and third boundary points of the respective hypothetical radial region define vertices of the triangle.

13. The display system of claim 9 wherein said first identifier includes:

a hue converter that determines a hue angle for each first sourced color point and outputs a hue index signal representing the determined hue angle.

14. The display system of claim 13 wherein said hue index signal represents a full rotation around the hue circle as a binary coded index value.

15. The display system of claim 13 wherein said second identifier includes:

a plurality of multiplexers each having plural input terminals and an input selection port, where said hue index signal is coupled to the to input selection ports of the plural multiplexers and where the selectable input terminals of the multiplexers receive input signals representing different conversion matrices applied to the first sourced color points.

16. The display system of claim 9 wherein said common interior point is the white point of the displayable color space.

17. The display system of claim 9 wherein said common interior point is an off white point of the displayable color space.

18. The display system of claim 17 wherein said M unique primary colors include white.

19. The display system of claim 9 wherein said M unique primary colors include cyan.

20. The display system of claim 9 wherein said signal converter includes a matrix multiplier and a storage storing matrix coefficients of the prespecified plurality of conversion matrices.

21. The display system of claim 20 wherein said matrix multiplier is a 3 by 3 matrix multiplier.

22. The display system of claim 9 wherein said first sourced color points are defined by coordinate signals specifying coordinates in CIE XYZ space.

23. The display system of claim 22 and further comprising:

(e) a gamut converter that produces the first sourced color points from supplied second sourced color points where the supplied second sourced color points are defined by an N primaries color space.