# US 9,520,103 B2 · RGB-to-RGBW color converting system and method

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- Number: US 9,520,103 B2
- Document ID: US9520103B2
- Status: Granted
- Kind: B2
- Application number: 14/385,992
- Filed: 2014-07-25
- Published: 2016-09-15
- Granted: 2016-12-13
- Earliest claimed: 2014-07-17
- Assignees: Shenzhen China Star Optoelectronics Technology Co., Ltd.
- Applicants: Shenzhen China Star Optoelectronics Technology Co., Ltd.
- Inventors: Lixuan Chen
- Web page: https://patentgrep.com/patent/US9520103B2

## CPC

- 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)}
- G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)}
- G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED]
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- G09G 5/04: using circuits for interfacing with colour displays
- H04N 9/67: for matrixing (camera processing pipelines for matrixing of colour signals H04N23/85)
- G09G 2300/0452: Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
- G09G 2320/0626: for control of overall brightness
- G09G 2320/0666: for control of colour parameters, e.g. colour temperature
- G09G 2340/06: Colour space transformation
- H10K 59/351: {comprising more than three subpixels, e.g. red-green-blue-white [RGBW]}
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A RGB-to-RGBW color converting system includes: a linearization section for linearizing inputted RGB values; a comparing section for comparing the linearized RGB values to obtain maximum and minimum values; a binarization section for performing a brightness binarization on the linearized RGB values to obtain a brightness binarization value; a gain value determining section for comparing a percentage of number of pixels corresponding to the brightness binarization value to all number of pixels in an image with a preset percentage to obtain a gain value; an output value calculating section for calculating RGBW output values according to the linearized RGB values, the maximum value, the minimum value, the gain value and the preset percentage. Accordingly, the addition of W sub-pixel unit would not result in the decrease of RGB output values, so that the color saturation can be improved while the whole brightness of image is maintained.

## Claims

### Claim 1

A RGB-to-RGBW color converting system comprising:
a linearization section, configured to linearize inputted RGB values;
a comparing section, configured to compare the linearized RGB values to thereby obtain a maximum value and a minimum value;
a binarization section, configured to perform a brightness binarization processing on the linearized RGB values to thereby obtain a brightness binarization value;
a gain value determining section, configured to compare a percentage of number of pixels corresponding to the brightness binarization value to all number of pixels in an image with a preset percentage to thereby obtain a gain value; and
an output value calculating section, configured to calculate out RGBW output values according to the linearized RGB values, the maximum value, the minimum value, the gain value and the preset percentage, the RGBW output values being used for image display on a display panel.

### Claim 2 (depends on 1)

The color converting system as claimed in claim 1, wherein if the gain value determining section judges that the percentage of the number of pixels corresponding to the brightness binarization value to the all number of pixels in the image is greater than the preset percentage, the gain value determining section obtains the gain value using the expression 1:
K=1/M,
where K represents the gain value, and M represents the preset percentage.

### Claim 3 (depends on 1)

The color converting system as claimed in claim 1, wherein if the gain value determining section judges that the percentage of the number of pixels corresponding to the brightness binarization value to the all number of pixels in the image is not greater than the preset percentage, the gain value determining section obtains the gain value using the expression 2:
K=M,
where K represents the gain value, and M represents the preset percentage.

### Claim 4 (depends on 1)

The color converting system as claimed in claim 1, wherein the output value calculating section comprises:
a judging section, configured to judge the minimum value whether is greater than 0 or equal to 0;
a white output value calculating section, configured to calculate out the W output value according to the judge result and the gain value;
a red output value calculating section, configured to calculate out the R output value according to the linearized R value, the maximum value, the W output value and the preset percentage;
a green output value calculating section, configured to calculate out the G output value according to the linearized G value, the maximum value, the W output value and the preset percentage; and
a blue output value calculating section, configured to calculate out the B output value according to the linearized B value, the maximum value, the W output value and the preset percentage.

### Claim 5 (depends on 4)

The color converting system as claimed in claim 4, wherein if the judging section judges that the minimum value is greater than 0, the white output value calculating section calculates out the W output value using the expression 3:
Wo=K×[MIN(Ri,Gi,Bi)]2;
the red output value calculating section calculates out the R output value using the expression 5:
Ro=M×Ri×Wo/MAX(Ri,Gi,Bi)+Ri−Wo;
the green output value calculating section calculates out the G output value using the expression 6:
Go=M×Gi×Wo/MAX(Ri,Gi,Bi)+Gi−Wo;
the blue output value calculating section calculates out the B output value using the expression 7:
Bo=M×Bi×Wo/MAX(Ri,Gi,Bi)+Bi−Wo;
where Wo represents the W output value, Ro represents the R output value, Go represents the G output value, Bo represents the B output value, Ri represents the linearized R value, Gi represents the linearized G value, the Bi represents the linearized B value, MAX (Ri, Gi, Bi) represents the maximum value, MIN (Ri, Gi, Bi) represents the minimum value, K represents the gain value, and M represents the preset percentage.

### Claim 6 (depends on 4)

The color converting system as claimed in claim 4, wherein if the judging section judges that the minimum value is equal to 0, the white output value calculating section calculates out the W output value using the expression 4:
Wo=0;
the red output value calculating section calculates out the R output value using the expression 5:
Ro=M×Ri×Wo/MAX(Ri,Gi,Bi)+Ri−Wo;
the green output value calculating section calculates out the G output value using the expression 6:
Go=M×Gi×Wo/MAX(Ri,Gi,Bi)+Gi−Wo;
the blue output value calculating section calculates out the B output value using the expression 7:
Bo=M×Bi×Wo/MAX(Ri,Gi,Bi)+Bi−Wo;
where Wo represents the W output value, Ro represents the R output value, Go represents the G output value, Bo represents the B output value, Ri represents the linearized R value, Gi represents the linearized G value, the Bi represents the linearized B value, MAX (Ri, Gi, Bi) represents the maximum value, MIN (Ri, Gi, Bi) represents the minimum value, K represents the gain value, and M represents the preset percentage.

### Claim 7

A RGB-to-RGBW color converting method comprising:
linearizing inputted RGB values;
comparing the linearized RGB values to thereby obtain a maximum value and a minimum value;
performing a brightness binarization processing on the linearized RGB values to thereby obtain a brightness binarization value;
comparing a percentage of number of pixels corresponding to the brightness binarization value to all number of pixels in an image with a preset percentage to thereby obtain a gain value; and
calculating out RGBW output values according to the linearized RGB values, the maximum value, the minimum value, the gain value and the preset percentage, the RGBW output values being used for image display on a display panel.

### Claim 8 (depends on 7)

The color converting method as claimed in claim 7, wherein if the percentage of the number of pixels corresponding to the brightness binarization value to the all number of pixels in the image is greater than the preset percentage, obtaining the gain value using the expression 1:
K=1/M,
Where K represents the gain value, and M represents the preset percentage.

### Claim 9 (depends on 7)

The color converting method as claimed in claim 7, wherein if the percentage of the number of pixels corresponding to the brightness binarization value to the all number of pixels in the image is not greater than the preset percentage, obtaining the gain value using the expression 2:
K=M,
Where K represents the gain value, and M represents the preset percentage.

### Claim 10 (depends on 7)

The color converting method as claimed in claim 7, wherein the step of calculating out RGBW values comprises:
judging the minimum value whether is greater than 0 or equal to 0; and
based on the judging result, using the gain value, the linearized RGB values, the maximum value, the W output value and the preset percentage to calculate out the RGBW output values.

### Claim 11 (depends on 10)

The color converting method as claimed in claim 10, if the minimum value is greater than 0, calculating out the RGBW output values using the following expression 3, expression 5, expression 6 and expression 7:
Wo=K×[MIN(RiGiBi)]2 expression 3:
Ro=M×Ri×Wo/MAX(RiGiBi)+Ri−Wo expression 5:
Go=M×Gi×Wo/MAX(RiGiBi)+Gi−Wo expression 6:
Bo=M×Bi×Wo/MAX(RiGiBi)+Bi−Wo expression 7:
where Wo represents the W output value, Ro represents the R output value, Go represents the G output value, Bo represents the B output value, Ri represents the linearized R value, Gi represents the linearized G value, the Bi represents the linearized B value, MAX (Ri, Gi, Bi) represents the maximum value, MIN (Ri, Gi, Bi) represents the minimum value, K represents the gain value, and M represents the preset percentage.

### Claim 12 (depends on 10)

The color converting method as claimed in claim 10, if the minimum value is equal to 0, calculating out the RGBW output values using the following expression 4, expression 5, expression 6 and expression 7:
Wo=0 expression 4:
Ro=M×Ri×Wo/MAX(RiGiBi)+Ri−Wo expression 5:
Go=M×Gi×Wo/MAX(RiGiBi)+Gi−Wo expression 6:
Bo=M×Bi×Wo/MAX(RiGiBi)+Bi−Wo expression 7:
where Wo represents the W output value, Ro represents the R output value, Go represents the G output value, Bo represents the B output value, Ri represents the linearized R value, Gi represents the linearized G value, the Bi represents the linearized B value, MAX (Ri, Gi, Bi) represents the maximum value, MIN (Ri, Gi, Bi) represents the minimum value, K represents the gain value, and M represents the preset percentage.