KR102091641B1 - Method and apparatus for adjusting chroma in rgb color space - Google Patents

Abstract

A method and apparatus for adjusting saturation in an RGB color space is provided. A saturation control method in an RGB color space according to an embodiment of the present invention includes: obtaining R, G, and B data in an RGB color space; Calculating the average value by averaging the R, G, and B data; And calculating saturation-adjusted R, G, and B data using a weighting factor α based on the respective R, G, and B data and the average value.

Description

METHOD AND APPARATUS FOR ADJUSTING CHROMA IN RGB COLOR SPACE}

The present invention relates to a method and apparatus for adjusting saturation in an RGB color space, and more specifically, while maintaining the brightness with R, G, B data directly in the RGB color space without conversion to an HSI color space or a YCbCr color space, A method and apparatus for adjusting saturation in an RGB color space capable of adjusting saturation.

There is a series of color image processing (eg. Color complements, Tone and color correction, Smoothing, Histogram equalization, etc) applied to imaging devices such as cameras and displays. One of the frequently used functions is to adjust the saturation (Chroma, Saturation) of the image.

In general, the saturation (chroma) adjustment corresponds to a color component in the HSI (Hue / Saturation / Intensity) color space or YCbCr (Luma component / Chrominance blue / Chrominance red) color space. S (Saturation, saturation) and Cb (blue-differnce, Chrominance blue) / Cr (red-difference, Chrominance red) were controlled.

1 is a diagram showing an HSI color space.

Referring to FIG. 1, HSI may be defined in a form in which two cones are pasted up and down. Since the color (Hue) is defined as a circle, it is expressed as an angle of 0 to 360 degrees, and the intensity (Intensity) has a minimum value of 0 at the lower vertex of the cone and a maximum value of 1 at the upper vertex. Saturation is expressed as the distance extending radially from the center of the circle in the shape of a circle that appears when the brightness is fixed, and has a value between 0 and 1. In addition, 0 ° to 120 ° means a red series (R), 120 ° to 240 ° means a green system (G), and 240 ° to 360 ° means a blue system (B). When RGB is converted to HSI, the conversion formulas of Hue (saturation), Saturation, and Intensity are as shown in Equations 1 to 3 below.

2 is a diagram illustrating a YCbCr color space. In addition, FIG. 3 shows the relationship between saturation (Hue), which is information about the color of the HSI color space, and Chromaticity (Cb, Cr), which is information about the color of the YCbCr color space. It is a drawing.

Referring to FIG. 2, Y (Luminance), Cb (Chrominance blue), and Cr (Chrominance red) are illustrated by three-dimensional graphing, and Equation 4 below converts RGB to YCbCr, Y, Cb, Cr It shows.

Here, referring to FIG. 3, Saturation and Hue, which are information on the color of the HSI color space, and the color of the YCbCr color space The relationship of information Chromaticity (Cb, Cr) is shown.

4 is a view showing a conventional general saturation control method.

Conventional general saturation control method was controlled by controlling S or CbCr in HIS or YCbCr color space. For example, as illustrated in FIG. 4, when saturation adjustment is required in the RGB color space easily accessible in the input image A1, HSI or YCbCr color space in the RGB color space After converting to (S1), after adjusting the saturation (S3), a process of converting from HSI or YCbCr color space to RGB color space (S5) is required.

However, in the process of converting such a color space, a loss of information occurs and a problem that an amount of computation increases is inevitable, so a method for solving this is required.

Republic of Korea Patent Publication No. 2011-0047669 (2011.05.09. Published) Japanese Patent Application Publication No. 2002-330299 (November 15, 2002) Japanese Patent Application Publication No. 8-275010 (released on October 18, 1996)

The present invention is to solve the above problem, without going through a separate color space conversion process, using the R / G / B data in the RGB color space, saturation adjustment in the RGB color space that can control the saturation while maintaining the contrast Methods and apparatus.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A method for adjusting saturation in an RGB color space according to an embodiment of the present invention for achieving the above problems includes: obtaining R, G, and B data in an RGB color space; Calculating the average value by averaging the R, G, and B data; And calculating saturation-adjusted R, G, and B data using a weighting factor α based on the respective R, G, and B data and the average value.

A saturation control apparatus in an RGB color space according to an embodiment of the present invention for achieving the above object includes: a data acquisition unit that acquires R, G, and B data in an RGB color space; An average value calculating unit that averages the R, G, and B data to calculate an average value; And a data correction unit that calculates R, G, and B data that is saturated by using a weighting factor α based on the respective R, G, and B data and the average value.

Other specific matters of the present invention are included in the detailed description and drawings.

According to the present invention, the saturation can be adjusted while maintaining the brightness with R, G, and B data directly in the RGB color space without conversion to the HSI color space or YCbCr color space.

1 is a diagram showing an HSI color space.
2 is a diagram illustrating a YCbCr color space.
FIG. 3 is a diagram illustrating a relationship between saturation (Hue), which is information on the color of the HSI color space, and Chromaticity (Cb, Cr), which is information on the color of the YCbCr color space. .
4 is a view showing a conventional general saturation control method.
5 is a flowchart of a method for adjusting saturation in an RGB color space according to an embodiment of the present invention.
6 is a configuration diagram of a saturation control device in an RGB color space according to an embodiment of the present invention.
7A to 7G are diagrams illustrating an image by a saturation control method in an RGB color space according to an embodiment of the present invention when the weighting factor α is gradually decreased.
8A to 8E are views illustrating an image by a saturation control method in an RGB color space according to an embodiment of the present invention when the weighting factor α is gradually increased.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Although the first, second, etc. are used to describe various elements, components and / or sections, it goes without saying that these elements, components and / or sections are not limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Accordingly, it goes without saying that the first element, the first component or the first section mentioned below may be the second element, the second component or the second section within the technical spirit of the present invention.

The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, the singular form also includes the plural form unless otherwise specified in the phrase. As used herein, "comprises" and / or "made of" mentioned components, steps, operations, and / or elements are those of one or more other components, steps, operations, and / or elements. Presence or addition is not excluded.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings commonly understood by those skilled in the art to which the present invention pertains. In addition, terms defined in the commonly used dictionary are not ideally or excessively interpreted unless specifically defined.

Hereinafter, the present invention will be described in more detail according to the accompanying drawings.

5 is a flowchart of a method for adjusting saturation in an RGB color space according to an embodiment of the present invention.

5, the saturation control method in the RGB color space according to an embodiment of the present invention, by obtaining R, G, B data in the RGB color space (S10), by averaging the R, G, B data The average value is calculated (S20), and the saturation-adjusted R, G, and B data is calculated using the respective R, G, and B data and a weighting factor α based on the average value (S30). At this time, the weighting factor α serves to linearly connect the R, G, and B data and the brightness. Therefore, it is possible to control the color component with only R, G, and B values in the RGB color space. In addition, it is preferable that the weighting factor α has a value between 0 and 1, but it is not limited thereto, and it will be apparent to those skilled in the art that a predetermined value can be set by the user.

Here, in obtaining the average value by averaging R, G, and B data, Equation 5 below may be used.

Equation 5 is the same as I (Intensity) in the HSI color space as described above, and represents the brightness.

In addition, in calculating the saturation-adjusted R, G, and B data, Equations 6 to 8 below may be used.

,

,

는 각각 채도 조절된 R, G, B 데이터이며, 상기

는 상기 수학식 5의 평균치를 의미한다. 즉, 상기

,

,

는 각각 채도(Saturation) 및 Chromaticity가 조절된 후의 R, G, B 값을 나타낸다. 이때, 명도(Brightness)의 경우, 특별한 변환 과정 없이 R, G, B의 평균으로 간단하게 연산될 수 있는 점을 이용하였다.Here, above

,

,

Are R, G, and B data with saturation adjusted, respectively.

Means the average value of Equation 5 above. That said

,

,

Indicates R, G, and B values after saturation and Chromaticity are adjusted, respectively. In this case, in the case of brightness, a point that can be simply calculated as the average of R, G, and B without using a special conversion process was used.

Looking at the above three equations 6, 7, and 8, it can be seen that the components for the color of each component are controlled according to the constant value. That is, the weighting factor α serves as a weight that linearly connects the R, G, and B components and the average I. Therefore, as the weighting factor α decreases, the weight applied to R, G, and B decreases and the weight of I increases, so the color component decreases and the intensity component increases relatively. On the other hand, as the weighting factor α increases, the weights of R, G, and B increase, and color and chromaticity components strongly enter.

If the weighting factor α becomes 0, the values of R, G, and B all converge to I, and the color component is completely missing, leaving only the information of brightness. Conversely, if the weighting factor α is 1, R, G, and B are inherently Will have the value of As a result, it is possible to control the color component with only R, G, and B values in the R, G, and B color spaces.

Equation (9) below shows that there is no change in brightness before and after control even after controlling the color (chrom) component using the saturation control method in the RGB color space according to an embodiment of the present invention.

As demonstrated in Equation 9 above, it can be seen that the change of the I value before and after the control does not occur even after controlling the color (chrom) component by the saturation adjustment method in the RGB color space according to an embodiment of the present invention. have.

6 is a block diagram of an apparatus for adjusting saturation in an RGB color space according to an embodiment of the present invention.

Referring to FIG. 6, the saturation adjusting device in the RGB color space according to an embodiment of the present invention includes a data acquisition unit 10 for acquiring R, G, and B data in the RGB color space, and the R, G, and B data An average value calculation unit 20 for calculating an average value by averaging, and a data correction unit for calculating saturation-controlled R, G, B data using a weighting factor α based on the respective R, G, B data and the average value 30.

,

,

를 산출하게 된다. 본 발명의 일 실시예에 따른 RGB 색 공간에서 채도 조절 장치의 구체적인 채도 조절 과정은 전술한 본 발명의 일 실시예에 따른 RGB 색 공간에서 채도 조절 방법과 실질적으로 동일하므로 생략하도록 한다.The data acquisition unit 10 acquires R, G, and B data, and the average value calculation unit 20 calculates the average value I by Equation 5, and the data correction unit 30 by Equations 6 to 8 Saturation adjusted R, G, B data

,

,

Will yield The specific saturation adjustment process of the saturation adjusting device in the RGB color space according to an embodiment of the present invention is substantially the same as the saturation adjustment method in the RGB color space according to an embodiment of the present invention, so it will be omitted.

7A to 7F are views illustrating an image by a saturation control method in an RGB color space according to an embodiment of the present invention when the weighting factor α is gradually decreased. 8A to 8E are diagrams showing an image by a saturation control method in an RGB color space according to an embodiment of the present invention when the weighting factor α is gradually increased.

Referring to FIGS. 7A to 7F, the original images (FIG. 7A) and the weighting factors α are 1 (FIG. 7B), 0.8 (FIG. 7C), 0.5 (FIG. 7D), 0.3 (FIG. 7E), and 0.1 (in order) 7F) and 0 (FIG. 7G). It can be seen from FIG. 7B that the weighting factor α is 1, resulting in an original image, and as the weighting factor α decreases, a color (chromaticity) component decreases and a brightness component increases.

8A to 8E, the original images (FIG. 8A) and the weighting factor α in order are 1.2 (FIG. 8B), 1.5 (FIG. 8C), 1.8 (FIG. 8D), and 2.0 (FIG. 8E). It is the result video of the time. It can be seen that as the weighting factor α increases, the weights of R, G, and B increase, and color and chromaticity components become stronger.

Accordingly, R, G, and B data are saturated directly in the RGB color space without undergoing a conversion process to an HSI color space or a YCbCr color space through a saturation adjustment method and apparatus in the RGB color space according to an embodiment of the present invention. Can be adjusted. It will be apparent to those skilled in the art that saturation adjustment in such an RGB color space can be used in the image processing portion in all imaging systems. For example, it can be applied to any video device that can be adopted by a person skilled in the art, such as a camera for surveillance, a camera for a mobile device such as a smartphone, and a camcorder.

On the other hand, the saturation control method and apparatus in the RGB color space according to an embodiment of the present invention can be implemented as one module by software and hardware, and the above-described embodiments of the present invention can be written as a program that can be executed on a computer And, it may be implemented in a general-purpose computer that operates the program using a computer-readable recording medium. The computer-readable recording medium is embodied in the form of a magnetic wave such as a ROM, floppy disk, or hard disk, an optical medium such as a CD or DVD, and a carrier wave such as transmission through the Internet. In addition, the computer-readable recording medium may be distributed over a networked computer system so that the computer-readable code is stored and executed in a distributed manner.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing its technical spirit or essential features. You will understand. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: data acquisition unit
20: average value calculation unit
30: data correction unit

Claims (3)

Obtaining R, G, and B data for each pixel in the RGB color space;
Calculating the average value of each pixel by averaging the R, G, and B data for each pixel; And
Comprising the step of calculating the saturation-controlled R, G, B data by calculating a weighted average between the R, G, B data for each pixel and the average value for each pixel using a weighting factor α,
A method of adjusting saturation in an RGB color space, wherein the average of the obtained R, G, and B data for each pixel and the average of the adjusted R, G, and B data for each pixel are the same. According to claim 1,
The calculating the R, G, and B data for each pixel of which the saturation is adjusted is,

,

,

Is calculated by,
Here, above

,

,

Is R, G, and B data for each saturation-adjusted pixel, wherein I is the average value for each pixel, and the saturation adjustment method in the RGB color space. A data acquisition unit that acquires R, G, and B data for each pixel in the RGB color space;
An average value calculating unit that averages the R, G, and B data for each pixel to calculate an average value for each pixel; And
A data correction unit for calculating R, G, and B data for each saturation-adjusted pixel by calculating a weighted average between the R, G, and B data for each pixel and the average value for each pixel using a weighting factor α,
The saturation adjustment device in the RGB color space, wherein the average of the obtained R, G, and B data for each pixel and the average of the saturation-adjusted R, G, and B data for each pixel are the same.

Images