JP2011027944A - Device, method and program for processing video signal, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processing device for improving a contrast and enhancing image quality by selectively adjusting luminance based on a video signal, a video signal processing method, a program and a display device. <P>SOLUTION: The video signal processing device includes: a first color space converting part for outputting a hue signal, a saturation signal and a first luminance signal for each pixel based on an input video signal consisting of an R signal, a G signal and a B signal; a margin value calculating part for calculating a margin value for each hue based on the hue signal; a control value setting part for setting a control value, by which the first luminance signal is regulated based on the saturation signal and the margin value of each hue, for each pixel; a luminance adjusting part for adjusting luminance of the first luminance signal based on the first luminance signal and the control value and outputting an adjusted second luminance signal; and a second color space converting part for converting the color space based on the hue signal, the saturation signal and the second luminance signal, and outputting an output video signal consisting of an R signal, a G signal and a B signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a video signal processing device, a video signal processing method, a program, and a display device.

  In recent years, as an alternative to a CRT display (Cathode Ray Tube display), an organic EL display (Organic Light Emitting Diode display) or FED (Field Emission Display) is used. Various display devices such as LCD (Liquid Crystal Display) and PDP (Plasma Display Panel) have been developed.

  The display device described above including a CRT display has a predetermined dynamic range for each device, and can display an image indicated by an input video signal within a limited dynamic range.

  Under such circumstances, in order to improve the contrast in a limited dynamic range, a technology for creating a correction curve for a video signal based on the video signal and correcting the video signal according to the created correction curve is available. Has been developed. As a technique for improving the sense of contrast by detecting a histogram of a luminance signal based on a video signal and correcting the video signal based on the detected histogram, for example, Patent Document 1 is cited.

  In addition, a technique for converting the color space of the input video signal and adjusting the brightness based on the video signal whose color space has been converted has been developed. An output-side device that converts the color space of the input video signal to the input video signal, and outputs the video signal by adjusting the hue of the video signal converted from the color space and adjusting the lightness based on the saturation As a technique for converting into a video signal expressed in the color reproduction region in Japanese Patent Application Laid-Open No. H10-228707, for example, Patent Literature 2 can be cited.

JP 2004-302111 A JP 2005-184602 A

[1] A problem in a conventional video signal processing apparatus that corrects a video signal based on a histogram of a luminance signal based on a video signal A conventional technique for correcting a video signal based on a histogram of a luminance signal based on a video signal (hereinafter, “ The video signal processing apparatus to which “Technology 1” is sometimes applied) corrects the video signal so that the contrast of the gradation whose histogram shows the maximum frequency is improved.

  8 to 10 are explanatory diagrams for explaining a conventional technique for correcting a video signal based on a histogram of luminance signals based on the video signal. When an image as shown in FIG. 8 is input, the video signal processing apparatus to which the conventional technique 1 is applied derives a luminance signal histogram based on the video signal as shown in FIG. Then, the video signal processing apparatus to which the conventional technique 1 is applied corrects the video signal based on the derived histogram so that the contrast of the gradation “128” indicating the maximum frequency is improved (FIG. 10).

  As described above, the conventional technique 1 corrects the video signal so that the contrast of the gradation whose histogram shows the maximum frequency is improved. By using the conventional technique 1, it is possible to enhance the feeling of contrast. Therefore, there is a possibility that the conventional video signal processing apparatus to which the conventional technique 1 is applied can improve the image quality. However, the conventional video signal processing apparatus to which the conventional technique 1 is applied cannot improve the image quality for an arbitrary video signal. Hereinafter, a problem in the conventional video signal processing apparatus to which the conventional technique 1 is applied will be described more specifically with reference to the drawings.

  FIG. 11 is an explanatory diagram for explaining a problem in the video signal processing apparatus to which the related art 1 for correcting the video signal based on the histogram of the luminance signal based on the video signal is applied. In FIG. 11, a video signal represented by 8 bits, that is, a video signal capable of representing 256 gradations is shown as an example. Here, FIG. 11A shows an example of an image that causes a problem in the conventional video signal processing apparatus. FIG. 11B shows a signal (R signal) corresponding to a red component (Red, hereinafter referred to as “R”) at each position on the line ab shown in FIG. Similarly, FIG. 11C shows a signal (G signal) corresponding to a green (hereinafter referred to as “G”) component, and FIG. 11D shows a blue (hereinafter referred to as “B”) component. 11 (d) shows a luminance signal (Y signal). As is clear from the signals in FIGS. 11B to 11E, the image shown in FIG. 11A shows a red (R) system image in which the left half of the image has different brightness. In addition, the right half of the image shows a yellow (Ye) system image with different brightness. Note that the Y signal is derived by the following Equation 1 according to the signal levels of the R signal, G signal, and B signal constituting the video signal. In FIG. The case of 28 ″ is taken as an example.

Y = 0.3R + 0.59G + 0.11B
... (Formula 1)

  In the case of the image shown in FIG. 11A, for example, a clearer image can be obtained by improving the color contrast in the yellow portion of the image (P in FIG. 11A). Here, adjusting the color contrast as described above is called, for example, color saturation adjustment (or also called color adjustment). However, since the signal level of the red portion of the image (Q in FIG. 11 (a)) has already reached the maximum value, if the degree of saturation is further increased, the signal level is oversaturated, and the image quality is deteriorated. .

  FIG. 12 is an explanatory diagram illustrating a case where the image illustrated in FIG. 11A is oversaturated by adjusting the color saturation, and an example in which the saturation in the image illustrated in FIG. 11A is doubled. Is shown. FIG. 12A shows an example of an image when the image shown in FIG. 11A is supersaturated by adjusting the color saturation, and FIGS. 12B to 12E. These show the R signal, G signal, B signal, and Y signal at each position on the line ab shown in FIG.

  By increasing the degree of saturation twice from the state of FIG. 11, the signal levels of the R signal and G signal in the yellow system portion in the right half of the image are increased as shown in FIGS. 12 (b) and 12 (c). Since it is twice, the contrast in the right half of the image is improved. However, as shown in FIG. 12B, the red half portion of the left half of the image is oversaturated and the step of the red tone is impaired. That is, in the image shown in FIG. 12A, the image quality is degraded.

  As shown in FIGS. 11 and 12, when the saturation level is simply controlled, the image quality may be degraded. Here, in the related art 1, as shown in FIGS. 8 to 10, the video signal is corrected so that the contrast of the gradation whose histogram shows the maximum frequency is improved, so that the conventional technique 1 is used. In this case, image quality degradation similar to that in FIG. 12 may occur.

  Therefore, even if the conventional technique 1 is used, it is not desired to improve the image quality.

[2] Problems in the conventional video signal processing apparatus to which the conventional technique for converting the color space of the input video signal and adjusting the brightness based on the video signal having the converted color space is input. A conventional video signal processing apparatus to which a technology (hereinafter, sometimes referred to as “conventional technology 2”) for converting the color space is applied and brightness is adjusted based on the video signal obtained by converting the color space is disclosed. The brightness is adjusted by converting the color space and processing the image signal. However, the video signal processing apparatus to which the conventional technique 2 is applied is premised on the conversion to the video signal expressed in the color reproduction region in the output side apparatus that outputs the video signal, and the process of rotating the hue Is required. Further, the video signal processing apparatus to which the conventional technique 2 is applied adjusts the lightness of the video signal whose hue is rotated. That is, for example, even when a video signal representing the image shown in FIG. 11A is input, the image represented by the video signal output from the conventional video signal processing apparatus to which the conventional technique 2 is applied is The image is not always constant. More specifically, when a video signal representing an image shown in FIG. 11 (a) is input, a video signal output from a conventional video signal processing apparatus to which the conventional technique 2 is applied (an image whose hue has been rotated). The image represented by the video signal) may even be an image that is similar to or not similar to the image illustrated in FIG.

  Therefore, even if a conventional technique for converting the color space of the input video signal and adjusting the brightness based on the video signal whose color space has been converted is not desired to achieve high image quality.

  As shown in [1] and [2] above, even if the conventional technique 1 and / or the conventional technique 2 are used, it is not desired to improve the image quality by improving the contrast.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve contrast by improving brightness by selectively adjusting brightness based on an input video signal. It is an object of the present invention to provide a new and improved video signal processing device, video signal processing method, program, and display device that can be realized.

  To achieve the above object, according to the first aspect of the present invention, based on an input video signal comprising an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component. A first color space conversion unit that converts a color space and outputs a hue signal, a saturation signal, and a first lightness signal based on the input video signal for each pixel; and a maximum value of lightness based on the hue signal A control value for adjusting the first lightness signal is set for each pixel based on a margin value deriving unit that derives a margin value for each hue for each hue, and the saturation signal and the margin value for each hue. Based on the control value setting unit, the first lightness signal, and the control value set in the control value setting unit, the lightness of the first lightness signal is adjusted for each pixel, and the adjusted second lightness signal is output. Brightness adjustment unit, the hue signal, and A second color space conversion unit that converts a color space based on the brightness signal and the second brightness signal adjusted in the brightness adjustment unit and outputs an output video signal composed of an R signal, a G signal, and a B signal; A video signal processing apparatus is provided.

  With this configuration, it is possible to improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  The brightness adjustment unit may output the second brightness signal by multiplying the control value for each pixel by the first brightness signal for each pixel.

  With this configuration, the brightness can be adjusted for each pixel within a margin range with respect to the maximum value of brightness.

  Further, the control value setting unit further sets the control value based on the upper limit stipulation information in which an upper limit stipulated value that regulates the upper limit of the control value for each hue is set for each hue, and the above margin for each corresponding hue. When the upper limit specified value is equal to or greater than the margin value, the margin value is selectively used, and when the upper limit specified value is smaller than the margin value, the above limit value is compared with the upper limit specified value. The control value may be set by selectively using the upper limit specified value.

  With this configuration, it is possible to adjust the brightness for each pixel within a margin range with respect to the maximum value of brightness and based on the control value according to the upper limit of the control value defined in the upper limit defining information.

  In order to achieve the above object, according to the second aspect of the present invention, an input video signal comprising an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component. A color space based on the input video signal, outputting a hue signal, a saturation signal, and a first brightness signal based on the input video signal for each pixel; and a margin for a maximum value of brightness based on the hue signal. Deriving a margin value to be shown for each hue, setting a control value for adjusting the first brightness signal for each pixel based on the saturation signal and the margin value for each hue, and the first Adjusting the brightness of the first brightness signal for each pixel based on the brightness signal and the control value set in the setting step, and outputting the adjusted second brightness signal; the hue signal; Degree signal And converting the color space based on the adjusted the second lightness signal, R signal, G signal, and a video signal processing method and a step of outputting an output image signal comprising a B signal.

  By using such a method, it is possible to improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  In order to achieve the above object, according to a third aspect of the present invention, an input video signal comprising an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component. The color space is converted on the basis of the input video signal, the hue signal, the saturation signal, and the first brightness signal based on the input video signal are output for each pixel, and the margin for the maximum value of brightness is indicated based on the hue signal. Deriving a margin value for each hue, setting a control value for adjusting the first brightness signal for each pixel based on the saturation signal and the margin value for each hue, and the first brightness signal; Adjusting the brightness of the first brightness signal for each pixel based on the control value set in the setting step, outputting the adjusted second brightness signal, the hue signal, the saturation signal, and Converting the color space based on the integer has been the second lightness signal, R signal, G signal, and a program for executing the steps on a computer for outputting an output image signal comprising a B signal.

  By using such a program, it is possible to improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  In order to achieve the above object, according to a fourth aspect of the present invention, an input video signal is composed of an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component. A video signal adjustment unit that adjusts the tone for each pixel, and a video display unit that displays an image on a display screen based on the video signal adjusted by the video signal adjustment unit, wherein the video signal adjustment unit includes the input video A color space is converted based on the signal, and a hue signal, a saturation signal, and a first lightness signal based on the input video signal are output for each pixel, and a lightness based on the hue signal A margin value deriving unit for deriving a margin value for each hue for each maximum hue value, and a control value for adjusting the first brightness signal for each pixel based on the saturation signal and the margin value for each hue. Control value setting unit to be set to A lightness adjusting unit that adjusts the lightness of the first lightness signal for each pixel based on one lightness signal and the control value set in the control value setting unit, and outputs the adjusted second lightness signal; and the hue A second color for converting the color space based on the signal, the saturation signal, and the second brightness signal adjusted by the brightness adjustment unit, and outputting an output video signal composed of an R signal, a G signal, and a B signal A display device including a space conversion unit is provided.

  With this configuration, it is possible to improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  According to the present invention, it is possible to improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

It is explanatory drawing for demonstrating the margin value derivation | leading-out process in the video signal processing apparatus concerning embodiment of this invention. It is explanatory drawing which shows an example of the setting method of the control value in the video signal processing apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating an example of the upper limit prescription | regulation information which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the adjustment result of the brightness in the video signal processing apparatus which concerns on embodiment of this invention. It is a block diagram which shows an example of a structure of the video signal processing apparatus which concerns on embodiment of this invention. 3 is a flowchart illustrating an example of a video signal processing method according to an embodiment of the present invention. It is a block diagram which shows an example of a structure of the display apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the prior art which correct | amends a video signal based on the histogram of the luminance signal based on a video signal. It is explanatory drawing for demonstrating the prior art which correct | amends a video signal based on the histogram of the luminance signal based on a video signal. It is explanatory drawing for demonstrating the prior art which correct | amends a video signal based on the histogram of the luminance signal based on a video signal. It is explanatory drawing for demonstrating the problem in the conventional video signal processing apparatus which correct | amends a video signal based on the histogram of the luminance signal based on a video signal. FIG. 12A is an explanatory diagram illustrating a case where the image illustrated in FIG. 11A is oversaturated by adjusting the color saturation.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Approach for improving contrast according to an embodiment of the present invention)
Before describing the configuration of a video signal processing apparatus according to an embodiment of the present invention (hereinafter sometimes referred to as “video signal processing apparatus 100”), first, in the video signal processing apparatus according to the embodiment of the present invention. An approach for improving contrast will be described.

  In the following, a video signal input to the video signal processing apparatus 100 (hereinafter sometimes referred to as an “input video signal”) includes an R signal corresponding to a red component, a G signal corresponding to a green component, and Although described as a video signal composed of a B signal corresponding to the blue component, it is not limited to the above. For example, the video signal processing apparatus 100 can also convert a video signal represented in another color space such as a YCrCb space into an RGB color space and process it. Here, the video signal according to the embodiment of the present invention may indicate a still image or may indicate a moving image.

[Outline of Approach According to Embodiment of the Present Invention]
The video signal processing apparatus 100 sets the brightness (value or brightness) for each pixel (for each video signal corresponding to each pixel) based on the hue and saturation value indicated by the input video signal. The same shall apply hereinafter.) The contrast is improved by adjusting. More specifically, the video signal processing apparatus 100 derives a margin value indicating a margin of brightness for each hue, and sets a control amount for adjusting the brightness based on the margin value and saturation derived for each hue. By determining each, the brightness is adjusted based on the input video signal.

  The video signal processing apparatus 100 derives a margin value for each hue corresponding to the input video signal, and adjusts the brightness within a margin indicated by the margin value for a brightness signal (described later) corresponding to each pixel. For example, the contrast can be improved while preventing the image quality from being deteriorated due to oversaturation as shown in FIG.

  In addition, since the video signal processing apparatus 100 adjusts the brightness for each pixel based on the hue and saturation according to the input video signal as described above, the conventional video signal processing apparatus to which the conventional technique 2 is applied. Thus, the hue does not change greatly (for example, a change that the user feels a color change).

  Therefore, the video signal processing apparatus 100 can improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

[Example of processing for realizing the approach according to the embodiment of the present invention]
Next, the process for realizing the approach according to the embodiment of the present invention will be described more specifically. The video signal processing apparatus 100 improves the contrast of the image by performing, for example, the following processes (1) to (3) on the input video signal. In the following, the process for realizing the approach according to the embodiment of the present invention in the video signal processing apparatus 100 will be described by taking as an example the case where the image indicated by the input video signal is the image shown in FIG. To do.

(1) First Color Space Conversion Processing The video signal processing apparatus 100 is based on an input video signal composed of an R signal, a G signal, and a B signal for each pixel (for each video signal corresponding to each pixel). Convert color space to HSV space. Here, the reason why the video signal processing apparatus 100 converts the color space into the HSV space is to adjust the lightness based on the hue and the saturation as described above.

  When the video signal processing apparatus 100 performs the process (1), the input video signal is a hue signal representing a hue (hereinafter also referred to as “hue signal (H)”), and a saturation representing saturation. Signal (hereinafter sometimes referred to as “saturation signal (S)”) and a lightness signal representing lightness (hereinafter sometimes referred to as “first lightness signal (V)”). Here, the video signal processing apparatus 100 converts the input video signal composed of the R signal, the G signal, and the B signal into a hue signal (H) and a saturation signal (S) by using, for example, the following formulas 2 to 4. ), And the first lightness signal (V). In the following equation, the R signal is represented as “Ri”, the G signal as “Gi”, and the B signal as “Bi”, the hue signal (H) as “H”, and the saturation signal (S) as “S”, The first brightness signal (V) is represented as “V”. In the following formula, the maximum value of the R signal, the G signal, and the B signal in the video signal corresponding to each pixel is “MAX”, and the minimum value of the R signal, the G signal, and the B signal is “ MIN ".

(2) Lightness Adjustment Process The video signal processing apparatus 100 adjusts the lightness based on the hue signal (H), the saturation signal (S), and the first lightness signal (V) converted by the process (1). To do. Hereinafter, the brightness signal whose brightness has been adjusted may be referred to as a “second brightness signal (V ′)”.

  More specifically, the video signal processing apparatus 100 converts the first brightness signal (H) to the second brightness signal (H ′) by, for example, the following processes (2-1) to (2-3). Adjust to.

(2-1) Margin Value Deriving Process The video signal processing apparatus 100 derives, for each hue, a margin value indicating a margin for the maximum value of brightness based on the hue signal (H).

  FIG. 1 is an explanatory diagram for explaining margin value derivation processing in the video signal processing apparatus 100 according to the embodiment of the present invention. Here, FIG. 1 shows the relationship between hue and brightness detected by the video signal processing apparatus 100 based on the hue signal (H) corresponding to the input video signal representing the image shown in FIG. Yes. In FIG. 1, the horizontal axis represents the hue signal (H) [degree], and the vertical axis represents the lightness [%]. Here, in FIG. 1, the lightness is expressed as a percentage, but is not limited to the above. For example, the video signal processing apparatus 100 can also express brightness in the range of 0.0 to 1.0.

  The video signal processing apparatus 100 detects a color component included in the image indicated by the input video signal based on the hue signal (H), and derives a margin value for each hue based on the detection result. For example, when attention is paid to the hue Ye in FIG. 1, it can be seen that the hue Ye has a margin of 50% with respect to the maximum value of brightness (100%). The video signal processing apparatus 100 derives a margin value indicating, for example, “50” [%] for the hue Ye.

  For example, the video signal processing apparatus 100 derives a margin value corresponding to the detection result of the color component included in the image indicated by the input video signal for each hue. Note that the method of expressing the margin value according to the embodiment of the present invention is not limited to being expressed in percentage. For example, the video signal processing apparatus 100 can derive a margin value obtained by converting the percentage into a value in the range of 0.0 to 1.0.

(2-2) Control Value Setting Process [1] First Control Value Setting Process The video signal processing apparatus 100 determines the margin value for each hue derived in (2-1), the saturation signal (S), and the like. Based on the above, a control value for adjusting the brightness signal is set for each pixel.

  FIG. 2 is an explanatory diagram showing an example of a control value setting method in the video signal processing apparatus 100 according to the embodiment of the present invention. In FIG. 2, the horizontal axis represents the saturation signal (S), and the vertical axis represents the control value.

  Here, FIG. 2 shows an example of a control value setting method set for the pixel corresponding to the hue Ye shown in FIG. Note that the video signal processing apparatus 100 can set control values for pixels corresponding to other hues by a method similar to the control value setting method described with reference to FIG.

  In FIG. 2, the saturation signal (S) and the control value are expressed as percentages, but the present invention is not limited thereto. For example, the video signal processing apparatus 100 can derive a control value represented by a value obtained by converting the percentage into a value in the range of 0.0 to 1.0 according to the saturation signal (S).

  The video signal processing apparatus 100 performs, for example, the calculation shown in the following Expression 5 for each pixel based on the margin value for each hue derived in the process (2-1) and the saturation signal (S). Thus, the control value is uniquely derived. Here, “y” shown in Equation 5 represents a control value, and “p” represents a margin value of a hue corresponding to a pixel for which the control value is set. Further, “x” shown in Equation 5 represents the value of the saturation signal (S).

For example, when the video signal processing apparatus 100 sets a control value for a pixel corresponding to the hue Ye shown in FIG. 1, the margin value p is p = 50 [%]. The control value of “100 + 50 × (x / 100) ² ” can be derived by the above calculation. Therefore, a control value corresponding to the saturation signal (S) is uniquely set for the pixel.

  Note that the video signal processing apparatus 100 is not limited to setting the control value using Equation 5. For example, when processing the control value and the saturation signal (S) expressed in a format in which the percentage is converted to a value in the range of 0.0 to 1.0, the video signal processing 100 is, for example, By performing the calculation shown in FIG. 6 for each pixel, the control value can be uniquely derived.

  For example, as described above, the video signal processing apparatus 100 sets a control value that realizes nonlinear correction so that the amount of enhancement of brightness when the saturation is maximum is maximized for each pixel, thereby increasing the maximum brightness. A control value whose brightness is adjusted within a margin for the value is set. Therefore, even if the video signal processing apparatus 100 adjusts the first lightness signal (V) based on the control value set in the first control value setting process in the process (2-3) described later, FIG. As shown in FIG. 4, the image quality is not deteriorated due to oversaturation. Needless to say, the calculation for deriving the control value in the video signal processing apparatus 100 according to the embodiment of the present invention is not limited to the above formulas 5 and 6.

[2] Second Control Value Setting Process The control value setting process for setting the control value in the video signal processing apparatus 100 according to the embodiment of the present invention is not limited to the first control value setting process. For example, in the video signal processing apparatus 100, the margin value for each hue derived in (2-1), the saturation signal (S), and the upper limit regulation value that regulates the upper limit of the control value for each hue are set for each hue. The control value can also be set for each pixel on the basis of the upper limit regulation information set in.

  FIG. 3 is an explanatory diagram for explaining an example of the upper limit defining information according to the embodiment of the present invention. Here, in FIG. 3, as in FIG. 1, the horizontal axis indicates the hue signal (H) [degree], and the vertical axis indicates the lightness [%]. Further, the lightness [%] shown on the vertical axis in FIG. 3 corresponds to an upper limit specified value that defines the upper limit of the control value for each hue. In addition, in FIG. 3, although the brightness is represented by percentage, it is not restricted above. For example, the video signal processing apparatus 100 can also express brightness in the range of 0.0 to 1.0.

  The video signal processing apparatus 100 recognizes the upper limit value of the control value for each hue using the upper limit defining information as shown in FIG. For example, in the upper limit defining information shown in FIG. 3, the upper limit defining value of 50 [%] is set for the hue Ye, so the video signal processing apparatus 100 sets the upper limit of the control value to be set for the pixel corresponding to the hue Ye. (The upper limit value defined by the upper limit defining information) is recognized as 150 [%]. Further, since the video signal processing apparatus 100 is set with the upper limit specified value of 0% for the hue R, the upper limit value of the control value set for the pixel corresponding to the hue R (specified by the upper limit specified information). Is recognized as 100 [%].

  Here, the upper limit defining information can be, for example, information prescribed in advance recorded in a ROM (Read Only Memory) or the like, but is not limited thereto. For example, the video signal processing apparatus 100 can appropriately generate the upper limit defining information based on a user operation using an operation unit (described later).

  The video signal processing apparatus 100 selectively uses the margin value for each hue derived in (2-1) above and the upper limit specified value for each hue set in the upper limit specifying information, so that the saturation signal ( A control value corresponding to S) is set. That is, when performing the second control value setting process, the video signal processing apparatus 100 sets either the margin value or the upper limit specified value as the value of “p” shown in Formula 5 (or Formula 6) for each hue. By selectively using, a control value corresponding to the saturation signal (S) is set.

  More specifically, the video signal processing apparatus 100 compares the margin value with the upper limit specified value for each corresponding hue. The video signal processing apparatus 100 selectively uses the margin value when the upper limit prescribed value is equal to or larger than the margin value, and selectively uses the upper limit prescribed value when the upper limit prescribed value is smaller than the margin value. Set the control value. By setting the control value as described above, the video signal processing apparatus 100 sets the control value for each pixel within the margin for the maximum value of brightness and according to the upper limit of the control value defined in the upper limit defining information. Can be set.

  Therefore, even if the video signal processing apparatus 100 adjusts the first lightness signal (V) based on the control value set by the second control value setting process in the process (2-3) described later, FIG. As shown in FIG. 4, the image quality is not deteriorated due to oversaturation. Further, when the upper limit specified value is set based on, for example, a user operation, the video signal processing apparatus 100 can adjust the brightness according to the user's intention, and the upper limit specified value is determined in advance, for example. If it has been set, the video signal processing apparatus 100 can adjust the brightness according to the setting.

  The video signal processing apparatus 100 can set the control value for each pixel, for example, by performing the processes shown in the above [1] and [2]. The method for deriving the control value in the video signal processing apparatus 100 according to the embodiment of the present invention is not limited to the above.

(2-3) Lightness adjustment processing (second lightness signal (V ′) derivation processing)
The video signal processing apparatus 100 uses the control value derived in the process (2-2) and the first lightness signal (V) as a pixel to obtain the second lightness signal (V ′) whose lightness has been adjusted. Derived for each. Here, the video signal processing apparatus 100 derives the second brightness signal (V ′) by multiplying the first brightness signal (V) and the control value for each pixel, for example, using the control value as a coefficient.

(3) Second Color Space Conversion Processing The video signal processing apparatus 100 converts the color space for each pixel based on the hue signal (H), the saturation signal (S), and the second lightness signal (V ′). Conversion to RGB space (color space corresponding to the input video signal). Here, the video signal processing apparatus 100 converts the hue signal (H), the saturation signal (S), and the second lightness signal (V ′) into an R signal by using, for example, the following Expressions 7 to 15. It can be converted into a G signal and a B signal. In the following equation, the R signal is represented as “Ro”, the G signal as “Go”, and the B signal as “Bo”, the hue signal (H) as “H”, the saturation signal (S) as “S”, The second lightness signal (V ′) is represented as “V ′”.

<When saturation signal (S) = 0>

<When saturation signal (S) ≠ 0>

  The video signal processing apparatus 100 performs, for example, the calculation shown in the above formulas 7 to 15 for each pixel, and thereby the R signal whose brightness is adjusted for each pixel (hereinafter sometimes referred to as “Ro signal”). , G signal (hereinafter may be referred to as “Go signal”), and B signal (hereinafter may be referred to as “Bo signal”).

  The video signal processing apparatus 100, for example, performs the above process (1) (first color space conversion process), (2) process (brightness adjustment process), and (3) process (second color space conversion process). The brightness of the input video signal is adjusted for each pixel by performing a conversion process. Here, in the process (2), the video signal processing apparatus 100 derives a margin value for each hue, and sets a control value for adjusting the brightness signal within a margin range with respect to the maximum brightness value defined by the margin value. Set for each pixel. Further, the video signal processing apparatus 100 adjusts the first brightness signal (V) for each pixel according to the set control value. That is, the video signal processing apparatus 100 changes the control amount for changing the brightness for each pixel within a margin range with respect to the maximum brightness value detected based on the hue signal (H). Then, the video signal processing apparatus 100 outputs the Ro signal, the Go signal, and the Bo signal based on the hue signal (H), the saturation signal (S), and the second brightness signal (V ′) whose brightness is adjusted for each pixel. Output to. Therefore, the video signal processing apparatus 100 can realize the approach according to the embodiment of the present invention described above by the processes (1) to (3).

  FIG. 4 is an explanatory diagram showing an example of the brightness adjustment result in the video signal processing apparatus 100 according to the embodiment of the present invention. Here, FIG. 4 shows an example of a processing result obtained when the video signal processing apparatus 100 processes the input video signal representing the image shown in FIG. 4A shows an example of an image indicated by the video signal (output video signal) output from the video signal processing apparatus 100, and FIGS. 4B to 4E show FIGS. An R signal (Ro signal), a G signal (Go signal), a B signal (Bo signal), and a Y signal at each position on the line ab shown in (a) are shown.

  As described above, the video signal processing apparatus 100 changes the control amount for changing the brightness for each pixel within a margin range with respect to the maximum value of the brightness detected based on the hue signal (H). Therefore, as shown in FIGS. 4B to 4E, the video signal processing apparatus 100 does not impair the step of the red gradation as shown in FIG. The contrast in can be improved.

  Therefore, the video signal processing apparatus 100 can improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  In addition, the process for implement | achieving the approach which concerns on embodiment of this invention is not restricted above. For example, the video signal processing apparatus 100 does not perform the process (3) (the second color space conversion process), and the hue signal (H), the saturation signal (S), and the brightness are adjusted second. The brightness signal (V ′) can also be output as an output video signal. Even in the above case, the video signal processing apparatus 100 can selectively adjust the brightness based on the input video signal, so that the contrast can be improved and the image quality can be improved.

(Video signal processing apparatus 100 according to an embodiment of the present invention)
Next, the processing (1) (first color space conversion processing) to (3) processing (second color space conversion processing) according to the approach according to the embodiment of the present invention described above may be performed. A possible configuration of the video signal processing apparatus 100 will be described.

  In the following description, it is assumed that the video signal input to the video signal processing apparatus 100 is a digital signal used in, for example, digital broadcasting. Further, the video signal input to the video signal processing apparatus 100 can be transmitted from a broadcast station or the like and received by the video signal processing apparatus 100, but is not limited thereto. For example, the video signal input to the video signal processing device 100 may be transmitted from an external device via a network such as a LAN (Local Area Network) and received by the video signal processing device 100, or The video signal processing apparatus 100 may read out a video file or an image file held in a storage unit (not shown) included in the video signal processing apparatus 100.

  FIG. 5 is a block diagram showing an example of the configuration of the video signal processing apparatus 100 according to the embodiment of the present invention. Here, in FIG. 5, the input video signal is indicated as Ri, Gi, Bi, and the video signal to be output (video signal whose brightness has been adjusted. Hereinafter, it may be referred to as “output video signal”). Are shown as Ro, Go, Bo.

  Referring to FIG. 5, the video signal processing apparatus 100 includes a first color space conversion unit 102, a margin value derivation unit 104, a control value setting unit 106, a brightness adjustment unit 108, and a second color space conversion unit 110. Is provided.

  The video signal processing apparatus 100 includes, for example, a control unit (not shown) configured by an MPU (Micro Processing Unit), various processing circuits, and the like that can control the entire video signal processing apparatus 100, and a control unit ( A RAM (Random Access Memory) that primarily stores a program used by a control unit (not shown) used by a control unit (not shown), a ROM (not shown) in which control data such as a program used by the program and calculation parameters are recorded. (Not shown), a receiving unit (not shown) that receives an image signal transmitted from a broadcasting station, a storage unit (not shown) that can store video files, image files, and the like, and an operation unit that can be operated by the user (Not shown), a communication unit (not shown) for communicating with an external device (not shown) may be provided. The video signal processing apparatus 100 connects the above-described constituent elements by, for example, a bus as a data transmission path. The control unit (not shown) serves as a first color space conversion unit 102, a margin value derivation unit 104, a control value setting unit 106, a brightness adjustment unit 108, and a second color space conversion unit 110, which will be described later. You can also.

  Here, as the storage unit (not shown), for example, a magnetic recording medium such as a hard disk, an EEPROM (Electrically Erasable and Programmable Read Only Memory), a flash memory, a MRAM (Magnetoresistive Random Access) Non-volatile memory such as Memory (RAM), FeRAM (Ferroelectric Random Access Memory), PRAM (Phase change Random Access Memory), and the like, but is not limited thereto. Further, examples of the operation unit (not shown) include operation input devices such as a keyboard and a mouse, buttons, direction keys, and combinations thereof, but are not limited thereto.

  The video signal processing device 100 and an external device (not shown) include, for example, a USB (Universal Serial Bus) terminal, an IEEE 1394 standard terminal, a DVI (Digital Visual Interface) terminal, or an HDMI (High-Definition Multimedia Interface). It may be physically connected via a terminal or the like, or may be connected wirelessly using WUSB (Wireless Universal Serial Bus), IEEE 802.11, or the like. Furthermore, the video signal processing apparatus 100 and an external apparatus (not shown) can be connected via a network, for example. Examples of the network include a wired network such as a LAN or a WAN (Wide Area Network), a wireless network such as a WLAN (Wireless Local Area Network) using MIMO (Multiple-Input Multiple-Output), or TCP / IP (Transmission Control). Examples include, but are not limited to, the Internet using a communication protocol such as Protocol / Internet Protocol. Therefore, the communication unit (not shown) has an interface corresponding to the connection form with the external device (not shown).

  The first color space conversion unit 102 serves to perform the process (1) (the first color space conversion process). That is, the first color space conversion unit 102 converts the input video signal (Ri signal, Gi signal, Bi signal) into a hue signal (H), a saturation signal (S), and a first lightness signal (V). Here, the first color space conversion unit 102 converts the input video signal including the Ri signal, the Gi signal, and the Bi signal into a hue signal (H) and a saturation signal (S ) And the first brightness signal (V), but the conversion method is not limited to the above.

  Here, the first color space conversion unit 102 includes a dedicated arithmetic circuit that performs the calculations of Formulas 2 to 4 above, whereby the input video signal is converted to the hue signal (H), the saturation signal (S), and the first shift. Although it converts into 1 lightness signal (V), it is not restricted above. For example, the first color space conversion unit 102 may be configured with an MPU or a general-purpose arithmetic circuit.

  The margin value deriving unit 104 serves to perform the process (2-1) (margin value deriving process). That is, the margin value deriving unit 104 derives, for each hue, a margin value indicating a margin for the maximum value of brightness based on the hue signal (H). Here, the margin value deriving unit 104 can be realized by, for example, a dedicated processing circuit that performs the process (2-1) (margin value deriving process), but is not limited thereto. For example, the margin value deriving unit 104 may be configured with an MPU or a general-purpose arithmetic circuit.

  The set value deriving unit 106 serves to perform the process (2-2) (control value setting process). More specifically, the set value deriving unit 106 sets a control value for adjusting the brightness signal for each pixel based on the margin value for each hue derived by the margin value deriving unit 104 and the saturation signal (S). Set (first control value setting process). Further, the set value deriving unit 106 sets a control value for adjusting the brightness signal for each pixel based on the margin value for each hue derived by the margin value deriving unit 104, the saturation signal (S), and the upper limit defining information. (Second control value setting process).

  Here, the control value setting unit 106 includes, for example, a dedicated arithmetic circuit that performs the calculation of the above mathematical formula 5 (or the mathematical formula 6), so that the margin value or the upper limit specified value and the saturation signal (S) are converted into the saturation value (S). The corresponding control value can be output, but is not limited to the above. For example, the video signal processing apparatus 100 can also configure the control value setting unit 106 with an MPU or a general-purpose arithmetic circuit.

  The brightness adjustment unit 108 plays a role of performing the above-described process (2-3) (brightness adjustment process). That is, the brightness adjustment unit 108 outputs the second brightness signal (V ′) for each pixel based on the control value output from the control value setting unit 106 and the first brightness signal (V). Here, the brightness adjustment unit 108 includes a multiplication circuit (arithmetic circuit) for multiplying the control value and the first brightness signal (V), thereby outputting the second brightness signal (V ′) for each pixel. However, it is not limited to the above. For example, the video signal processing apparatus 100 can also configure the brightness adjustment unit 108 with an MPU or a general-purpose arithmetic circuit.

  The second color space conversion unit 110 serves to perform the above-described process (3) (second color space conversion process). That is, the second color space conversion unit 110 converts the hue signal (H), the saturation signal (S), and the second lightness signal (V ′) into output video signals (Ro signal, Go signal, Bo signal). . Here, the second color space conversion unit 110 converts the hue signal (H), the saturation signal (S), and the second lightness signal (V ′) to the Ro signal by using, for example, the above Equations 7 to 15. , Go signal, and Bo signal, but the conversion method is not limited to the above.

  Here, the second color space conversion unit 110 includes a dedicated arithmetic circuit that performs the calculations of Formulas 7 to 15, so that the hue signal (H), the saturation signal (S), and the second brightness signal ( V ′) is converted into a Ro signal, a Go signal, and a Bo signal, but is not limited thereto. For example, the second color space conversion unit 110 may be configured with an MPU or a general-purpose arithmetic circuit. Further, the second color space conversion unit 110 and the first color space conversion unit 102 may be a common arithmetic circuit (or a configuration in which some arithmetic circuits are shared).

  The video signal processing apparatus 100 includes, for example, the first color space conversion unit 102, the margin value derivation unit 104, the control value setting unit 106, the brightness adjustment unit 108, and the second color space conversion unit 110 as described above ( The processing (1) (first color space conversion processing), the processing (2) (lightness adjustment processing), and the processing (3) (first color space conversion processing) are realized. Therefore, the video signal processing apparatus 100 can adjust the brightness of the input video signal for each pixel and output the output video signal with the adjusted brightness.

  The configuration of the video signal processing apparatus according to the embodiment of the present invention is not limited to the configuration shown in FIG. For example, the video signal processing apparatus according to the embodiment of the present invention has a configuration that does not include the second color space conversion unit 110, that is, a configuration that does not perform the process (3) (the conversion process of the second color space). You can also. Even with the above configuration, the video signal processing apparatus 100 can selectively adjust the brightness based on the input video signal.

  As described above, the video signal processing apparatus 100 according to the embodiment of the present invention includes the above-described processing (1) (first color space conversion processing), processing (2) (lightness adjustment processing), and By performing the process (3) (first color space conversion process), the brightness of the input video signal is adjusted for each pixel. Here, the video signal processing apparatus 100 derives a margin value for each hue in the process (2) described above, and sets a control value for adjusting the brightness signal within a margin range with respect to the maximum brightness value defined by the margin value. Set for each pixel. Further, the video signal processing apparatus 100 adjusts the first brightness signal (V) for each pixel according to the set control value. That is, the video signal processing apparatus 100 changes the control amount for changing the brightness for each pixel within a margin range with respect to the maximum brightness value detected based on the hue signal (H). Therefore, even if the video signal processing apparatus 100 adjusts the first lightness signal (V) based on the set control value, the image quality deterioration due to oversaturation as shown in FIG. 12 does not occur. Therefore, the video signal processing apparatus 100 can improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  As described above, the video signal processing apparatus 100 has been described as an embodiment of the present invention, but the embodiment of the present invention is not limited to such a form. Embodiments of the present invention include, for example, display devices such as CRT displays, organic EL displays, FEDs, LCDs, and PDPs, computers such as PCs (Personal Computers) and servers (Servers), and portable communication devices such as mobile phones. It can be applied to various devices. The video signal processing apparatus 100 can also be realized as an IC chip in which the units shown in FIG. 5 are integrated, for example. The application of the video signal processing apparatus 100 to a display device will be described later.

(Program related to video signal processing device)
A program for causing a computer to function as a video signal processing apparatus according to an embodiment of the present invention improves contrast by selectively adjusting brightness based on an input video signal to improve image quality. Can do.

(Video signal processing method according to an embodiment of the present invention)
Next, a video signal processing method according to an embodiment of the present invention will be described. FIG. 6 is a flowchart showing an example of the video signal processing method according to the embodiment of the present invention. In the following, the video signal processing method shown in FIG. 6 is described as being performed by the video signal processing apparatus 100. However, the video signal processing apparatus 100 is not limited to the above, and can be applied to a display apparatus according to an embodiment of the present invention described later.

  The video signal processing apparatus 100 converts an input video signal (Ri signal, Gi signal, Bi signal) into a hue signal (H), a saturation signal (S), and a first lightness signal (V) (S100, first). Color space conversion process). Here, the video signal processing apparatus 100 converts the input video signal into a hue signal (H), a saturation signal (S), and a first lightness signal (V) by using, for example, Equations 2 to 4 above. However, the conversion method is not limited to the above.

  The video signal processing apparatus 100 sets a margin value for each hue based on the hue signal (H) converted in step S100 (S102). Here, for example, the video signal processing apparatus 100 detects a color component included in an image indicated by the input video signal based on the hue signal (H), and derives a margin value corresponding to the detection result for each hue. To do.

  The video signal processing apparatus 100 sets a control value for each pixel based on the saturation signal (S) converted in step S100, the margin value set for each hue in step S102, and the upper limit defining information. (S104). Here, the video signal processing apparatus 100 selectively uses, for example, the margin value for each hue derived in (2-1) above and the upper limit specified value for each hue set in the upper limit specifying information. Then, a control value corresponding to the saturation signal (S) is set (second control value setting process).

  Note that the process related to the setting of the control value in the video signal processing method according to the embodiment of the present invention is not limited to the process shown in step S104. For example, the video signal processing apparatus 100 can set the control value for each pixel based on the saturation signal (S) converted in step S100 and the margin value set for each hue in step S102. (First control value setting process).

  The video signal processing apparatus 100 adjusts the first brightness signal (V) converted in step S100 for each pixel based on the control value set for each pixel in step S104 (S106). Here, the video signal processing apparatus 100 adjusts the first brightness signal (V) by multiplying, for example, the first brightness signal (V) and the control value set for each pixel for each corresponding pixel. It is not limited to the above.

  The video signal processing apparatus 100 outputs the hue signal (H) and saturation signal (S) converted in step S100 and the second brightness signal (V ′) adjusted in step S106 as an output video signal (Ro signal, Go signal, Bo signal) (S108: second color space conversion process). Here, the video signal processing apparatus 100 outputs the hue signal (H), the saturation signal (S), and the second lightness signal (V ′) to the output video signal (V ′) by using, for example, the above Equations 7 to 15. (Ro signal, Go signal, Bo signal), but is not limited to the above.

  By using the video signal processing method shown in FIG. 6, the video signal processing apparatus 100 can improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal. .

  Note that the video signal processing method according to the embodiment of the present invention is not limited to the method shown in FIG. For example, the video signal processing apparatus 100 does not perform step S108 illustrated in FIG. 6, and the hue signal (H) and the saturation signal (S) converted in step S100 and the second lightness signal ( V ′) can also be output as an output video signal. Even in the case of using the above video signal processing method, the video signal processing apparatus 100 can selectively adjust the brightness based on the input video signal, thereby improving the contrast and improving the image quality. Can do.

(Display device according to an embodiment of the present invention)
Next, a display device to which the video signal processing device according to the embodiment of the present invention is applied will be described.

  FIG. 7 is a block diagram showing an example of the configuration of the display device 200 according to the embodiment of the present invention. 7 is an embodiment of the display device according to the embodiment of the present invention, and it goes without saying that the embodiment of the present invention is not limited to the configuration of FIG. In the following description, it is assumed that the video signal input to the display device 200 is an input video signal (Ri signal, Gi signal, Bi signal) similar to the video signal processing device 100 shown in FIG.

  Referring to FIG. 7, the display device 200 includes a video signal adjustment unit 202 and a video display unit 204.

  In addition, the display device 200 includes, for example, a control unit (not shown) configured by an MPU or the like and capable of controlling the entire display device 200, and control data such as programs and calculation parameters used by the control unit. ROM (not shown), a RAM (not shown) that primarily stores programs executed by the control unit, a storage unit (not shown) that can store various data such as display data for user interface, An operation unit (not shown) operable by a user, a receiving unit (not shown) that receives a video signal transmitted from a broadcasting station, and a communication unit (not shown) for communicating with an external device (not shown). (Not shown) or the like. The display device 200 connects the above-described components through a bus as a data transmission path, for example.

  Here, examples of the storage unit (not shown) include a magnetic recording medium such as a hard disk, and a nonvolatile memory such as an EEPROM and a flash memory, but are not limited thereto. Further, examples of the operation unit (not shown) include operation input devices such as a keyboard and a mouse, buttons, direction keys, and combinations thereof, but are not limited thereto.

  In addition, the display device 200 and an external device (not shown) may be physically connected via, for example, a USB terminal, a DVI terminal, or an HDMI terminal, or wirelessly using WUSB or the like. You can also connect with. Furthermore, the display device 200 and an external device (not shown) can be connected via a wired / wireless network, for example. Therefore, the communication unit (not shown) has an interface corresponding to the connection form with the external device (not shown).

  For example, the video signal adjustment unit 202 can have the same configuration as that of the video signal processing apparatus 100 according to the embodiment of the present invention shown in FIG. Therefore, the video signal adjustment unit 202 outputs an output video signal (Ro signal, Go signal, Bo signal) with improved contrast by selectively adjusting the brightness based on the input video signal.

  The video display unit 204 displays a video based on the video signal adjusted by the video signal adjustment unit 202.

[Configuration Example of Video Display Unit 204]
The video display unit 204 includes a display unit 206, a row driving unit 208, a column driving unit 210, a power supply unit 212, and a display control unit 214.

  The display unit 206 serves as a display screen that displays an image represented by the video signal. The display unit 206 includes, for example, a plurality of pixels arranged in a matrix (matrix). For example, a display unit that displays an SD (Standard Definition) resolution image has at least 640 × 480 = 307200 (data lines × scanning lines) pixels, and the pixels are R, G, and B for color display. In the case of being composed of sub pixels, it has 640 × 480 × 3 = 921600 (data lines × scanning lines × number of subpixels). Similarly, for example, a display unit that displays an HD (High Definition) resolution image has 1920 × 1080 pixels, and has 1920 × 1080 × 3 sub-pixels for color display.

  Further, the display unit 206 may include, for example, a pixel circuit (not shown) for controlling the amount of voltage / current applied to each pixel. The pixel circuit includes, for example, a switch element and a drive element for controlling the amount of current by an applied scanning signal and a voltage signal, and a capacitor for holding a voltage signal. The switch element and the drive element are composed of, for example, a thin film transistor.

  For example, the row driving unit 208 and the column driving unit 210 apply voltage signals to a plurality of pixels included in the display unit 206 to cause each pixel to emit light. Here, one of the row driving unit 208 and the column driving unit 210 applies a voltage signal (scanning signal) that determines ON / OFF of a pixel, and the other applies a voltage signal (video signal) corresponding to an image to be displayed. It can play the role of applying.

  Further, as a driving method of the row driving unit 208 and the column driving unit 210, for example, a dot-sequential driving scanning method in which light is emitted for each pixel arranged in the matrix form, and the pixels arranged in the matrix form for each column. Examples include a line sequential drive scanning method for emitting light, and a surface sequential drive scanning method for emitting light from all the pixels arranged in the matrix. Note that the video display unit 204 of the display device 200 shown in FIG. 8 includes two drive units, a row drive unit 208 and a column drive unit 210, but the display device according to the embodiment of the present invention has one drive. Needless to say, it can be composed of parts.

  The power supply unit 212 supplies power to the row driving unit 208 and the column driving unit 210, and a voltage is applied to the row driving unit 208 and the column driving unit 210. The magnitude of the voltage that the power supply unit 212 applies to the row driving unit 208 and the column driving unit 210 varies according to the video signal adjusted by the video signal adjusting unit 202.

  The display control unit 214 is composed of, for example, an MPU, and a voltage for determining ON / OFF of a pixel in one of the row driving unit 208 and the column driving unit 210 in accordance with the video signal adjusted by the video signal adjusting unit 202. Is input to the pixel, and a video signal is input to the other. The display control unit 214 can also control power supply to the row driving unit 208 and the column driving unit 210 by the power supply unit 212 in accordance with the video signal corrected by the video signal adjustment unit 202.

  The display device 200 according to the embodiment of the present invention has a configuration as shown in FIG. 7 to adjust an input video signal, and the video signal based on the adjusted video signal (output video signal). The image represented by can be displayed. Needless to say, the configuration of the display device 100 according to the embodiment of the present invention is not limited to the configuration shown in FIG.

  As described above, the display device 200 according to the embodiment of the present invention includes the video signal adjustment unit 202 having the same function and configuration as the video signal processing device 100 according to the above-described embodiment of the present invention. Therefore, the display device 200 can adjust the brightness of the input video signal for each pixel. Further, the display device 200 displays an image represented by the video signal based on the video signal (output video signal) whose brightness is adjusted. Therefore, the display device 200 can improve the contrast and improve the image quality by selectively adjusting the brightness based on the input video signal.

  Moreover, although the display apparatus 200 was mentioned and demonstrated as embodiment of this invention, embodiment of this invention is not restricted to this form. Embodiments of the present invention include, for example, a self-luminous display device such as a CRT display, an organic EL display, an FED, and a PDP, a backlight display device such as an LCD, and a television receiver that receives a television broadcast. It can be applied to machines. The embodiments of the present invention can be applied to various devices such as computers such as PCs and servers, and portable communication devices such as mobile phones.

(Program related to display device)
According to a program for causing a computer to function as the display device according to the embodiment of the present invention, the brightness is selectively adjusted based on the input video signal, thereby improving the contrast and improving the image quality. it can.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above description, it is shown that a program (computer program) for causing a computer to function as the image processing apparatus according to the embodiment of the present invention is provided. However, the embodiment of the present invention further includes the above program. A stored storage medium can also be provided.

  The configuration described above shows an example of the embodiment of the present invention, and naturally belongs to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Video signal processing apparatus 102 1st color space conversion part 104 Margin degree derivation part 106 Control value setting part 108 Lightness value adjustment part 110 2nd color space conversion part 200 Display apparatus 202 Video signal adjustment part 204 Video display part 206 Display part 208 Row drive unit 210 Column drive unit 212 Power supply unit 214 Display control unit

Claims (6)

A color space is converted based on an input video signal composed of an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component, and a hue signal and a saturation signal based on the input video signal , And a first color space converter that outputs a first brightness signal for each pixel;
Based on the hue signal, a margin value deriving unit that derives a margin value indicating a margin for the maximum value of brightness for each hue;
A control value setting unit that sets a control value for adjusting the first lightness signal for each pixel based on the saturation signal and the margin value for each hue;
A lightness adjusting unit that adjusts the lightness of the first lightness signal for each pixel based on the first lightness signal and the control value set in the control value setting unit, and outputs the adjusted second lightness signal;
A color space is converted based on the hue signal, the saturation signal, and the second lightness signal adjusted by the lightness adjustment unit, and an output video signal composed of an R signal, a G signal, and a B signal is output. A two-color space conversion unit;
A video signal processing apparatus comprising:   2. The video signal processing apparatus according to claim 1, wherein the brightness adjustment unit multiplies the control value for each pixel by the first brightness signal for each pixel and outputs the second brightness signal. . The control value setting unit further sets the control value based on upper limit defining information in which an upper limit defining value that defines the upper limit of the control value for each hue is set for each hue,
The margin value is compared with the upper limit value for each corresponding hue, and when the upper limit value is equal to or greater than the margin value, the margin value is selectively used, and the upper limit value is the margin value. 3. The video signal processing apparatus according to claim 1, wherein when the value is smaller than the value, the control value is set by selectively using the upper limit specified value. 4. A color space is converted based on an input video signal composed of an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component, and a hue signal and a saturation signal based on the input video signal And outputting a first brightness signal for each pixel;
Deriving a margin value for each hue indicating a margin for the maximum value of brightness based on the hue signal;
Setting a control value for adjusting the first brightness signal for each pixel based on the saturation signal and the margin value for each hue;
Adjusting the brightness of the first brightness signal for each pixel based on the first brightness signal and the control value set in the setting step, and outputting the adjusted second brightness signal;
Converting a color space based on the hue signal, the saturation signal, and the adjusted second lightness signal, and outputting an output video signal composed of an R signal, a G signal, and a B signal;
A video signal processing method comprising the steps of: A color space is converted based on an input video signal composed of an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component, and a hue signal and a saturation signal based on the input video signal And outputting a first brightness signal for each pixel;
Deriving a margin value for each hue indicating a margin for the maximum value of brightness based on the hue signal;
Setting a control value for adjusting the first lightness signal for each pixel based on the saturation signal and the margin value for each hue;
Adjusting the brightness of the first brightness signal for each pixel based on the first brightness signal and the control value set in the setting step, and outputting the adjusted second brightness signal;
Converting a color space based on the hue signal, the saturation signal, and the adjusted second lightness signal, and outputting an output video signal composed of an R signal, a G signal, and a B signal;
A program that causes a computer to execute. A video signal adjustment unit that adjusts, for each pixel, the gradation of an input video signal composed of an R signal corresponding to a red component, a G signal corresponding to a green component, and a B signal corresponding to a blue component;
A video display unit for displaying an image on a display screen based on the video signal adjusted by the video signal adjustment unit;
With
The video signal adjustment unit
A first color space conversion unit that converts a color space based on the input video signal and outputs a hue signal, a saturation signal, and a first lightness signal based on the input video signal for each pixel;
Based on the hue signal, a margin value deriving unit that derives a margin value indicating a margin for the maximum value of brightness for each hue;
A control value setting unit that sets a control value for adjusting the first lightness signal for each pixel based on the saturation signal and the margin value for each hue;
A lightness adjusting unit that adjusts the lightness of the first lightness signal for each pixel based on the first lightness signal and the control value set in the control value setting unit, and outputs the adjusted second lightness signal;
A color space is converted based on the hue signal, the saturation signal, and the second lightness signal adjusted by the lightness adjustment unit, and an output video signal composed of an R signal, a G signal, and a B signal is output. A two-color space conversion unit;
A display device comprising: