Method of Converting Signals For Multi-Primary Color Display

• US 20080252658A1
• Filed: 03/31/2006
• Published: 10/16/2008
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Cordes, Claus Nico, Belik, Oleg, Hekstra, Gerben Johan
• Granted Patent: US 8,237,747 B2
• Time in Patent Office: Days
• US Class Current: 345/604
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85

Abstract

A method is described which converts a three primary color input signal (Cx, Cy, Cz) into N drive signals (P1, . . . , PN) to drive N>3 primary colors of a multi-primary color display (3). The method determines (1) a valid range (VS) wherein the N drive signals (P1, . . . , PN) have valid values by performing the steps of (i) defining 3 functions representing 3 of the drive signals (P1, P2, P3) as a function of the remaining N−3 drive signal(s) (P4, . . . , PN), and (ii) calculating (1) a common range in a space formed by the N−3 drive signal(s) (P4, . . . , PN) wherein each one of the 3 functions has valid values. The method selects (2) a point from the common range to determine the N drive signals (P1, . . . , PN).

Claims

1. A method of converting a three primary color input signal (Cx, Cy, Cz) into N drive signals (P1, . . . , PN) for driving N>

3 primary colors of a multi-primary color display (3), the method comprises;

determining (1) a common range (VS) wherein the N drive signals (P1, . . . , PN) have valid values by performing the steps of (i) defining 3 functions representing 3 of the drive signals (P1, P2, P3) as a function of the remaining N−

3 drive signal(s) (P4, . . . , PN), and (ii) calculating (1) the common range (VS) in a space formed by the N−

3 drive signal(s) (P4, . . . , PN) wherein each one of the 3 functions has valid values, and

selecting (2) a point from the common range (VS) to determine the N drive signals (P1, . . . , PN).

2. A method as claimed in claim 1, wherein the 3 functions are defined by

$[\begin{array}{c}P\end{array}$



1 P 



2 P 



3 ] = [ P 



1 ′

P 



2 ′

P 



3 ′

] + [ k 



1 , 1 …

k 



1 , N - 3 k 



2 , 1 …

k 



2 , N - 3 k 



3 , 1 …

k 



3 , N - 3 ] ×

[ P 



4 …

PN ]

wherein P1 to PN are the N drive signals, (P1′

, P2′

, P3′

) are defined by the input color, and the coefficients ki,j define a dependence between 3 primaries associated with the 3 drive values P1, P2, P3, and the other primaries associated with the N−

3 drive signal(s) P4 to PN.

3. A method as claimed in claim 1, wherein the selecting (2) is performed under a constraint (CON) for at least one aspect of at least one of the 3 drive signals (P1, P2, P3).

4. A method as claimed in claim 3, wherein the constraint (CON) is that one of the drive signals (P1, P2, P3, P4) is selected to have a minimum possible drive value.

5. A method as claimed in claim 3, wherein the constraint (CON) is a real time constraint determined by at least one of the group of:

a temperature of the display (3), an amount of ambient light at the display (3), aging of the display (3), or a power consumption of the display (3).

6. A method as claimed in claim 1, wherein N=4, and wherein the 3 functions are defined by

$[\begin{array}{c}P\end{array}$



1 P 



2 P 



3 ] = [ P 



1 ′

P 



2 ′

P 



3 ′

] + [ k 



1 k 



2 k 



3 ] ×

P 



4

wherein P1 to P4 are the 4 drive signals, (P1′

, P2′

, P3′

) are defined by the input color, and the coefficients ki define a dependence between 3 primaries associated with the 3 drive values P1, P2, P3, and the other primary associated with the fourth drive signal P4.

7. A method as claimed in claim 6, wherein the calculating calculates the common range (VS) on a line formed by the fourth drive signal (P4), and wherein the common range (VS) defines a range wherein each one of the 3 functions has valid values.

8. A method as claimed in claim 7, wherein the calculating of the common range (VS) comprises:

calculating, for each one of the 3 functions, a lower border value of the fourth drive signal (P4) where the particular function reaches one of the border values of the valid range, and a higher border value of the fourth drive signal (P4) where the particular function reaches another border value of the valid range, and

determining the common range (VS) from the respective lower and higher border values (P4,min, P4,max).

9. A method as claimed in claim 1, wherein all drive values (P1 to PN) are normalized and wherein valid ranges are defined as the values in the range from zero to one, including its borders.

10. A system for converting a three primary color input signal (Cx, Cy, Cz) into N drive signals (P1, . . . , PN) for driving N>

3 primary colors of a multi-primary color display (3), the system comprises;

means for determining (1) a common range (VS) wherein all the N drive signals (P1, . . . , PN) have valid values comprising means for defining 3 functions representing 3 of the drive signals (P1, P2, P3) as a function of the remaining N−

3 drive signal(s) (P4, . . . , PN), and means for calculating (1) the common range (VS) in a space formed by the N−

3 drive signal(s) (P4, . . . , PN) wherein each one of the 3 functions has valid values, and

means for selecting (2) a point from the common range (VS) to determine the N drive signals (P1, . . . , PN).

11. A display apparatus comprising

a signal processing circuit (4) for receiving an image input signal (IV) to supply the primary color input signal (Cx, Cy, Cz),

the system as claimed in claim 10, and

a display device (3) for receiving the N drive signals (P1 to PN).