JP2004326082A5 - - Google Patents

Description

Display control device and display device

  The present invention relates to an image display control device that performs processing for improving the sense of contrast to an input signal, and a display device using the same.

  2. Description of the Related Art With the development of an information-oriented society, an opportunity to display an image on a display device and to see the image on a display device under various circumstances has increased. However, the display capability of the display device does not always reach a sufficient level, and a device for improving the visibility is required as compared with a case where the input signal is directly input to the display device.

  Regarding this point, Non-Patent Document 1 gives sharpness to an image by using a sigmoid function to make black (low gradation) blacker, white (high gradation) whiter, and further enhance the halftone contrast feeling. To improve the stereoscopic effect.

This sigmoid function is
y = {a} (1-r)｝ * {x ＾ r} (0 ≦ x ≦ a)
y = 1-{(1-a)} (1-r)｝ * {(1-x) ＾ r} (a <x ≦ 1)
Is a non-linear function. Here, the control value a is the most frequent value of the luminance histogram of the input signal, and the control value r is a constant.
"Tone conversion by sigmoid function in digital camera system", Watanabe et al., Japan Hardcopy2000 Transactions B-27, The Imaging Society of Japan

However, the technology described in Non-Patent Document 1 has the following problems 1 and 2.
(Problem 1) Since the sigmoid function is nonlinear, it cannot be realized by a simple arithmetic circuit. Therefore, it is not practical when considering hardware implementation.
(Problem 2) In Non-Patent Document 1, the most frequent value of the histogram is used as the control value of the sigmoid function. However, when the screen continuously changes, the control value is likely to greatly change from screen to screen, and flickering occurs in the converted image display.

  In general, a Y signal in a Yuv color space is used as luminance. Therefore, it is conceivable to use the Y signal in the processing for improving the contrast.

  However, the capacity of the Y signal in the Yuv color space is larger than the capacity of the brightness component in the RGB color space. Therefore, the processing for increasing the Y signal is performed without any special consideration, and then the inverse conversion from the Yuv color space to the RGB color space results in exceeding the capacity of the brightness component in the RGB color space. Cannot be displayed, resulting in a result, and eventually, a color blur occurs.

  For example, in the RGB color space, a signal of R = 0%, G = 0%, and B = 80% is converted into a Yuv color space, and the luminance is obtained as luminance Y = 24%. Then, when the process of doubling the luminance (permitted in the Yuv color space) is performed, the luminance Y is 48%.

  However, when the color after processing is inversely converted to the RGB color space, B> 100%, and the image cannot be displayed. In other words, the colors have collapsed.

  Therefore, an object of the present invention is to provide an image display control device that can be easily implemented as hardware, can suppress flicker in image display, and can suppress color collapse.

The display control device according to the first aspect of the invention includes a feature value calculation unit that calculates a feature value based on the input signal, and the conversion characteristic calculation unit determines a conversion characteristic based on the feature value.

  In this configuration, a process can be performed in which the characteristics of the input signal are reflected by the feature amount.

In a display control device according to a second aspect, a conversion characteristic calculator that adaptively determines a conversion characteristic for an input signal, and a signal converter that converts the input signal according to the conversion characteristic determined by the conversion characteristic calculator. A weight calculation unit that masks the input signal according to the weight characteristic, and a feature calculation unit that calculates a feature based on the input signal masked by the weight calculation unit. In this configuration, the conversion characteristic is determined based on the characteristic amount. By masking the input signal with the weight characteristic, unnecessary changes in the characteristic amount can be suppressed, and the occurrence of flicker can be reduced.

In the display control device according to the third aspect , the weight characteristic suppresses a low gradation signal and a high gradation signal in the input signal.

  This configuration is suitable for processing an image having many halftones, such as a natural image.

In the display control device according to the fourth aspect , the weight characteristic suppresses an intermediate gradation signal and a high gradation signal in the input signal.

  This configuration is suitable for processing an image having many low gradations, such as a dark image as a whole.

In the display control device according to the fifth aspect , the other color space is an RGB color space and a color space having the same capacity for brightness components, for example, an HSV color space.

  With this configuration, it is possible to prevent the color from fluctuating due to the change in the brightness component.

In the display control device according to the sixth aspect , the conversion characteristics include a horizontal axis as an input signal, a vertical axis as an output signal, and an area from the origin to full scale on the horizontal axis, a low gradation area near the origin, When divided into a high gradation region close to full scale and an intermediate gradation region located between the low gradation region and the high gradation region, the average inclination of the intermediate gradation region is It is determined to be larger than any of the average gradients in the high gradation area.

  With this configuration, the contrast of the halftone area can be coordinated in accordance with the input signal, the low gradation area (black) can be made blacker, and the high gradation area (white) can be made whiter, and the sharpness of the image can be improved.

In the display control device according to the seventh aspect, the feature value determines the position and range of the intermediate gradation area.

  With this configuration, the halftone area for enhancing the contrast can be dynamically changed in accordance with the characteristics of the input signal represented by the feature amount.

In the display control device according to the eighth aspect, the feature amount is an average luminance of an image represented by the input signal.

  In this configuration, since a more stable feature amount is used than the most frequently occurring value of the histogram, flicker in image display can be suppressed.

In the display control device according to the ninth aspect, the feature amount calculation unit outputs a signal for adjusting the output level of the signal conversion unit and the light emission level of the external light source with a correlation.

  With this configuration, in the display unit having the light source, the display level of the display device and the light emission level of the light source can be coordinated.

In the display control device according to the tenth aspect, when the maximum value on the vertical axis in the conversion characteristic is lower than the threshold, the feature amount calculation unit increases the output level of the signal conversion unit and decreases the light emission level of the external light source. To adjust.

  With this configuration, it is possible to reduce the power consumption by lowering the light emission level of the external light source on the display unit while obtaining a visually similar display result.

In the display control device according to the eleventh aspect, when the maximum value on the vertical axis in the conversion characteristic exceeds the threshold value, the feature amount calculation unit adjusts so as to increase the light emission level of the external light source.

  With this configuration, in the display unit, the light emission level can be increased in accordance with the high display level, and a more vivid display result can be obtained.

In the display control device according to the twelfth aspect , the conversion characteristic includes a plurality of line segments each having a predetermined slope.

  In this configuration, since linear processing is performed by line segments, the processing can be simplified, and it is easy to cope with hardware.

In the display control device according to the thirteenth aspect, one line segment exists in each of the low gradation region, the intermediate gradation region, and the high gradation region.

  In this configuration, the conversion characteristics can be simply handled by a total of three line segments.

A display control device according to a fourteenth aspect of the present invention provides a display control device which converts an input signal from an RGB color space to another color space, and separates a brightness component, a saturation component, and other components from each other. A luminance conversion unit that converts a brightness component according to the luminance conversion characteristic, a saturation conversion unit that converts a saturation component according to a constant saturation conversion characteristic, and a brightness component converted by the luminance conversion unit. An inverse color conversion unit that combines the saturation component converted by the saturation conversion unit with the other components and converts the color space from another color space to the RGB color space is provided. It consists of a set number of line segments.

  With this configuration, by using constant conversion characteristics irrespective of the input signal, the circuit scale when hardware is realized can be significantly reduced, and by processing the saturation component, not only the contrast but also the The vividness can be coordinated, and the visual quality can be improved. Further, the brightness component and the saturation component can be processed independently, and the image quality can be freely adjusted.

In the display control device according to the fifteenth aspect, the plurality of line segments of the saturation conversion characteristic form an upwardly convex polygonal line.

  With this configuration, since linear processing is performed by line segments, processing can be simplified, and it is easy to deal with hardware.

In the display control device according to the sixteenth aspect , the brightness component V is the maximum value of the RGB values, and the saturation component S is a value obtained by subtracting the minimum value of the RGB values from the maximum value of the RGB values. Divided by the maximum value of.

  With this configuration, the brightness component and the saturation component can be extracted with a simple operation, and the circuit scale when implemented as hardware can be reduced.

  According to the present invention, it is possible to obtain an image display control device that can be easily implemented in hardware and can suppress flicker and color collapse in image display.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
1 to 3 relate to the first embodiment. FIG. 1 is a block diagram of a display device according to Embodiment 1 of the present invention.

  In FIG. 1, a display unit 10 is an LCD, a CRT, or the like, and any display unit can be used as long as it can display a brightness component with a gradation.

The display control device 20 has an input terminal 24 and an output terminal 25, and controls a display state of the display unit 10 based on an output signal I ₁ from the output terminal 25.

In the display control device 20, the feature amount calculation unit 21 calculates a feature amount for one image based on an input signal I ₀ input from the input terminal 24. Here, in the present embodiment, the input signal I ₀ is a component of a video signal, and here is luminance. Any brightness component can be used as the brightness.

Then, an average value t of one image of the input signal I ₀ is used as the feature amount. This is because not only the calculation is easy, but also the appearance frequency of the entire image is high, the stability is higher than the most frequent value of the histogram, and the change between images is considered to be small.

That is, the feature value calculation unit 21 obtains an input signal I ₀ for one image, calculates an average value t of luminance, and outputs the average value t to the conversion characteristic calculation unit 22 as a feature value.

  The conversion characteristic calculating unit 22 receives the characteristic amount t from the characteristic amount calculating unit 21 and determines a conversion characteristic as shown in FIG. That is, the feature amount and the conversion characteristic are updated in principle for each frame.

As shown in FIG. 2, when the input signal I ₀ is plotted on the horizontal axis and the output signal I ₁ is plotted on the vertical axis, the conversion characteristics are full-scale from the origin (0, 0) (in this embodiment, 8-bit display). 255), a low gradation area near the origin (0 ≦ I ₀ <u, gradient r1), a high gradation area near full scale (v <I ₀ ≦ 255, gradient r3), When divided into the intermediate gradation area (u ≦ I ₀ ≦ v, slope r2) located between the two, r2> r1 and r2> r3. These slopes r1, r2, and r3 are constant values.

That is, one line segment exists in each of the low, medium, and high gradation areas. In this way, as described later in detail, a simple calculation of all linear, it is possible to obtain the output signal I _1, the hardware of it is easy.

  The feature value t determines the position and range of the halftone area in the conversion characteristics. That is, in this example, when the characteristic amount t is input, the conversion characteristic calculation unit 22 sets width A = width B = t / 4. Then, u = t−A and v = t + B. Thereby, the position and range of the halftone area are determined.

Next, the conversion characteristic calculation unit 22 draws a straight line having the slope r1 from the origin (0, 0), and obtains an intersection P1 between this straight line and a straight line where I ₀ = u. Further, the conversion characteristic calculation unit 22 draws a straight line having the slope r2 from the intersection point P1, and obtains an intersection point P2 with the straight line where I ₀ = v. Further, the conversion characteristic calculation unit 22 draws a straight line having an inclination r3 from the intersection P2, and obtains an intersection P3 with a straight line where I ₀ = 255. As described above, the line segments OP1, P1P2, and P2P3 are determined, and the conversion characteristics are determined.

  By the way, since the conversion characteristic depends on the characteristic amount t, when the characteristic amount t changes, the conversion characteristic changes from the state of FIG. For example, as shown in FIG. 3, when the feature amount t is reduced from the state of FIG. 2, the halftone area is narrowed, and the area shifts to the origin side.

  Conversely, when the feature amount t increases, the halftone area becomes wider and shifts to the full scale side.

Due to such a change in the conversion characteristic, adaptive display control is performed on the input signal I ₀ .

In FIG. 1, the signal conversion unit 23 receives the input signal I ₀ from the input terminal 24 and the conversion characteristic parameter obtained as described above from the conversion characteristic calculation unit 22. Then, the signal conversion unit 23 converts the input signal I ₀ according to the conversion characteristics, and outputs the output signal I ₁ to the display unit 10 via the output terminal 25.

  As a result, the contrast of the halftone area is coordinated around the average luminance, and the sharpness is improved. Further, since black becomes blacker and white becomes whiter, the sense of visual contrast is improved. Furthermore, since the conversion characteristics are limited to linear processing, hardware implementation is easy.

  Although three line segments are used in the above conversion characteristics, more line segments can be used without departing from the spirit of the present invention. In addition, the joint between the line segments may be rounded.

Further characteristic quantity t and / or conversion characteristic, the input signal I ₀ not itself an image to be displayed this time, based on an input signal relating to previous image may be calculated. In this way, when the screen changes continuously, the change in the conversion characteristics is smoothed, and a stable image quality is obtained.

(Embodiment 2)
4 and 5 relate to the second embodiment. FIG. 4 is a block diagram of a display device according to Embodiment 2 of the present invention. This embodiment is suitable when the display unit 30 includes the light source 32 and the display device 31 illuminated by the light source 32 (typically, when the display unit 30 is a backlight-type LCD). .

  In the display control device 40 of the present embodiment, the conversion characteristic calculator 22 and the signal converter 23 are the same as in the first embodiment. The light source adjusting device 45 provided at the next stage of the display control device 40 has a first output terminal 43 connected to the display device 31 and a second output terminal 44 connected to the light source 32.

In the present embodiment, in the light source adjustment device 45, a multiplication unit 42 is provided between the signal conversion unit 23 and the first output terminal 43, and the coefficient K from the feature amount calculation unit 41 to the multiplication unit 42 is output. ing. The multiplier 42 multiplies the output signal I ₁ by the coefficient K and outputs the result to the display device 31 as the output signal I ₂ . This output signal I ₂ determines the display level of the display device 31.

  Further, in the display control device 40, the feature amount calculation unit 41 outputs a light emission control signal P that determines the light emission level of the light source 32 to the second output terminal 44.

  Based on the coefficient K and the light emission control signal P, the feature amount calculation unit 41 adjusts the output level of the signal conversion unit 23 (the light emission level of the display device 31) and the light emission level of the light source 32 with a correlation. .

Specifically, as shown in FIG. 5, by a suitable feature amount t1, when by conversion characteristic S1, the maximum value max1 of the output signal I _1, as the reference value.

On the other hand, when max1> max2 as in the case of the maximum value max2 of the conversion characteristic S2 based on the characteristic amount t2, the characteristic amount calculation unit 41 obtains a coefficient K (= max1 / max2) and outputs the coefficient K to the multiplication unit 42. . Here, since K> 1, the output signal I ₂ becomes larger than the input signal I ₁ , and the light emission level of the display device 31 increases. In addition, the characteristic amount calculation unit 41 determines that the light emission control signal P = (max2 / max1) ^ γ (γ is one of the gradation characteristics of the display device 31 and, according to the CRT, γ is approximately 2.2. Values are often set). Thus, the amplification of the video signal of the display device 31 and the decrease in the brightness of the light source 32 are canceled. Therefore, power consumption by the light source 32 can be suppressed without lowering image quality.

On the other hand, when max1 <max3, such as the maximum value max3 of the conversion characteristic S3 based on the characteristic amount t3, the characteristic amount calculation unit 41 sets the coefficient K = max1 / max3, and as a result, the output signal I ₂ (= K * I ₁₎ is smaller than the input signal I _1. Further, the feature amount calculation unit 41 sets the light emission control signal P = (max1 / max3) ^ γ, and as a result, the light emission level of the light source 32 increases. Thereby, bright high-quality display can be performed. In addition, when the peak luminance decreases, the lifetime can be extended if the display unit 30 is an organic EL. Further, even if the input signal I ₁ exceeds the full scale (255 in this example), the output signal I ₂ can be reduced to be within the full scale. Therefore, color clips can be prevented.

In the above two cases, it is desirable to update the light emission control signal P and the coefficient K for each frame. However, the emission control signal P and the coefficient K, the input signal I ₀ not itself an image to be displayed this time, based on an input signal relating to previous image may be calculated. In this way, when the screen changes continuously, the change in the conversion characteristics is smoothed, and a stable image quality is obtained.

(Modification 1)
13 and 14 relate to a first modification of the second embodiment. As shown in FIG. 13, in the first modification, a light source adjustment unit 28 is provided between the display control device 40 and the display unit 30 instead of the light source adjustment device 45 (see FIG. 4) in the second embodiment. I have.

The light source adjustment unit 28 adjusts the output signal I ₂ to the display device 31 and the light emission control signal P to the light source 32 with a correlation based on the output signal I ₁ of the signal conversion unit 23. In this case, unlike FIG. 4, the feature amount calculation unit 41 does not need to obtain the coefficient K and the light emission control signal P.

The light source adjustment unit 28 performs the following processing. That is, the light source adjustment unit 28 receives the output signal I ₁ for one frame from the signal conversion unit 23 and obtains the maximum luminance value maxI ₁ illustrated in FIG.

Here, in this example, since the full scale is 255, the light source adjustment unit 28 sets the output signal I ₂ to the display device 31 = (255 / maxI ₁ ) * I ₁ .

Furthermore, to offset the change of the output signal I ₂ to the display device 31, light source adjustment unit 28, a light emission control signal P, defined as the brightness of the _{(maxI 1/255) ^ γ} (%). γ is as described above.

  Again, the above processing is performed for each frame.

  Thereby, the brightness of the light source 32 is reduced, and the power consumption is suppressed. Moreover, despite the decrease in the brightness of the light source 32, the above-described offset maintains the apparent image quality when the light source 32 is viewed below the image on the display device 31.

(Embodiment 3)
6 to 8 relate to the third embodiment. FIG. 6 is a block diagram of a display device according to Embodiment 3 of the present invention.

  In FIG. 6, the display unit 10 is the same as in the first embodiment. In addition, the display control device 50 includes a weight calculation unit 51.

Then, the weight calculation unit 51 masks the input signal I ₀ according to the weight characteristics as illustrated in FIG. 7 or FIG. 8 and outputs the result to the feature calculation unit 21. The feature amount is calculated based on the masked input signal.

This “mask” only needs to be masked as a result. For example, I ₀ * Weight (I ₀ ) can be used as the masked input signal.

Alternatively, the feature amount calculation unit 41 may obtain the feature amount by dividing the product sum of the weight coefficient (Weight (I ₀ )) and the input signal I ₀ by the weight cumulative value.

In particular,
Feature value = sum-of-product value / cumulative weight value = {I ₀ × Weight (I ₀ )} / {Weight (I ₀ )}
It becomes.

  Even in this case, in the present specification, it is assumed that the feature amount calculation unit 21 calculates the feature amount based on the masked input signal. Here, the calculation of the feature value may be performed by an equation, or an appropriate table may be prepared and referred to.

The weight characteristic of FIG. 7 is suitable for a natural image and the like. With this characteristic, the low gradation signal (0 ≦ I ₀ <Pa) and the high gradation signal (Pb <I ₀ ≦ 255) are suppressed, and as a result, the halftone signal (Pa ≦ I ₀ ≦ Pb) is preferentially treated. Things.

  In FIG. 7, a and b indicate inclinations, Pa and Pb indicate weight control points, and MaxW indicates a maximum weight. Here, the slopes a and b and the weight control points Pa and Pb may be constant values, but it is desirable to determine them adaptively with respect to the input image using a simple conversion formula with the average luminance as an argument.

The weight characteristic of FIG. 8 is suitable for an image that is entirely dark (for example, an image captured at night). This property suppresses halftone signal (Pa ≦ I ₀ ≦ Pb) and high gradation signal _{(Pb <I 0 ≦ 255)} , consequently, favors low gray level signal ₍₀ ≦ I 0 <Pa) Things.

  Since the preferred weight characteristics are different depending on the change of the situation such as the scene, the temperature, the illuminance, and the time, FIG. 7, FIG. 8 or other weight characteristics are prepared, and are configured to be switched according to the state of the image. It is desirable.

  In this way, by adding weights to the input signal in accordance with the state of the image, unnecessary changes in the feature amount can be suppressed, and the occurrence of flicker can be reduced.

(Modification 2)
FIG. 15 relates to a second modification of the first to third embodiments. For simplicity, the following description is based on Embodiment 1.

As shown in FIG. 15, in the second modification, a storage unit 29 is provided between the input terminal 24 and the signal conversion unit 23. Storage unit 29 is constituted by, for example, a memory or the like, having an area capable of storing input signal I ₀ of the one frame.

When the storage unit 29 is provided, the conversion characteristics determined by the feature amount calculation unit 21 and the conversion characteristic calculation unit 22 based on the input signal I ₀ of the N-th frame (N is a natural number) are converted to the input signal I _{0 of} the N-th frame. It is applicable to itself and is suitable.

  When the circuit scale is limited, the storage unit 29 may be omitted as shown in FIGS. 1, 4, and 6.

(Modification 3)
FIG. 16 relates to a third modification of the first to third embodiments. The third modification will be described based on the first embodiment, similarly to the second modification.

In short, in the third modification, the feature amount calculation unit 21 calculates a plurality of feature amounts for each input signal I _{0 for} one frame, and performs display control based on the plurality of feature amounts.

In FIG. 16, the dividing unit 100 receives an input signal I _{0 for} one frame (indicating one image as a whole) and divides it into a plurality of partial images for each area. The division method is arbitrary. For example, when the input signal I ₀ conforms to a format that can be distinguished for each object may be divided into partial images for each object.

  More simply, the number of pixels and positions of a plurality of areas may be fixedly determined, and the division unit 100 may divide the partial image according to the determination. At this time, each area may have the same size. Alternatively, the image may be divided into partial images of a relatively small area near the center of a frame that is easily noticeable, and may be divided into partial images of a relatively large area near an outer edge that is not easily noticeable.

  Furthermore, when an image of one frame is composed of a plurality of screens, such as a child screen, a parent screen, or a character screen and an image screen, the image may be divided for each screen.

  In any case, in Modification 3, the dividing unit 100 outputs a plurality of partial images from the image for one frame to the input selector 101 and the output selector 102. The input selector 101 selects one of the partial images and outputs the selected partial image to the feature amount calculation unit 21. Thereafter, as described above, the conversion characteristic calculation unit 22 calculates a conversion characteristic suitable for the partial image, and outputs the conversion characteristic to the output selector 102.

  The output selector 102 outputs the current partial image and conversion characteristics suitable for the partial image to the signal conversion unit 23.

  The above processing is repeatedly executed for all the partial images in the image of one frame.

  As shown in FIG. 16, in the third modification, only one set of the feature amount calculation unit 21 and the conversion characteristic calculation unit 22 is provided. However, when the number of partial images per frame is known, the number of pairs of the feature amount calculation unit 21 and the conversion characteristic calculation unit 22 may be provided in parallel to increase the processing speed.

  When the signal conversion is performed for each partial image in this manner, display control can be performed more finely, and display quality can be improved accordingly.

(Embodiment 4)
9 and 10 relate to the fourth embodiment. FIG. 9 is a block diagram of a display device according to Embodiment 4 of the present invention. In the present embodiment, in the RGB color space and the HSV color space having the same capacity for the brightness component, the brightness component is converted using the conversion characteristics to prevent color blur. Here, the HS1S2V color space obtained by improving the HSV color space is used, but a normal HSV color space may be used.

In FIG. 9, a feature value calculation unit 21, a conversion characteristic calculation unit 22, and a signal conversion unit 23 are the same as those in the first embodiment, but the signal conversion unit 23 and the feature value calculation unit 21 include a luminance input signal I ₀ However, the difference is that the color conversion unit 60 inputs a brightness component V obtained when the color conversion unit 60 converts from the RGB color space to the HSV color space.

Further, the color conversion unit 60 outputs the hue H and the saturation S by conversion in addition to the brightness component V. Specifically, the color conversion section 60 converts the RGB signals into the HS1S2V color space by the following equation.
Brightness component V = max (R, G, B)
First saturation S1 = (V−min (R, G, B) / V)
Second saturation S2 = {mid (R, G, B) -min (R, G, B)} / {V-min (R, G, B)}
Note that the hue H is a parameter indicating the magnitude relationship between R, G, and B, and the color conversion unit 60 selects the hue as shown in FIG. With such a conversion formula, the brightness component and the saturation component can be extracted with a simple operation, and the circuit scale when hardware is realized can be reduced.

  Also, max (), min (), and mid () mean the maximum value, the minimum value, and the median value in parentheses, respectively.

Further, in FIG. 9, the inverse color conversion unit 61 converts the HS1S2V color space into the RGB color space using the output (brightness component) of the signal conversion unit 23 and other components according to the following equation.
Value MAX = V
Value MID = (1- (1-S2)) * V)
Value MIN = (1-S1) * V
Further, the inverse color conversion unit 61 substitutes the corresponding value among the value MAX, the value MID, and the value MIN into the R value, the G value, and the B value according to the state of the hue H illustrated in FIG.

  As a result, the contrast can be adjusted without causing a blur.

  It should be noted that Embodiments 1 to 4 described above can be appropriately combined and configured.

(Embodiment 5)
11 and 12 relate to the fifth embodiment. FIG. 11 is a block diagram of a display device according to Embodiment 5 of the present invention. In the present embodiment, in the RGB color space and the HSV color space having the same capacity for the brightness component, the brightness component is converted using the conversion characteristics to prevent color blur. Although the HSV color space is used here, an HS1S2V color space obtained by improving the HSV color space may be used.

  In FIG. 11, a color conversion unit 60 converts an input signal from an RGB color space to an HSV color space, and separates the input signal into a brightness component V, a saturation component S, and a hue component H.

  The brightness conversion unit 72 converts the brightness component V according to a certain brightness conversion characteristic stored in the brightness conversion characteristic storage unit 71.

  The saturation conversion unit 74 converts a saturation component according to a fixed saturation conversion characteristic stored in the saturation conversion characteristic storage unit 73.

  As shown in FIG. 12, in the present embodiment, the saturation conversion characteristic is composed of two line segments each having a defined gradient (a gradient rC1 below the inflection point pC and a gradient rC2 above the inflection point pC). Constitutes an upwardly convex polygonal line.

  In the present embodiment, the gradient rC1> the gradient rC2 is set in order to enhance the contrast of the halftone. By using a plurality of line segments, saturation conversion with a high degree of freedom can be performed. For example, in FIG. 12, when the saturation is emphasized in the section from 0 to pC1, the vividness of low saturation can be improved.

  In addition, since linear processing is performed by line segments, processing can be simplified, and it is easy to deal with hardware.

  In FIG. 11, the inverse color conversion unit 61 combines the brightness component converted by the brightness conversion unit 72, the saturation component converted by the saturation conversion unit 74, and the hue component H, and generates an HSV color. Convert from space to RGB color space.

  The luminance conversion characteristic storage unit 71 and the saturation conversion characteristic storage unit 73 can use a fixed conversion characteristic irrespective of the input signal, so that the circuit scale when hardware is realized can be greatly reduced. By processing the components, not only the contrast but also the vividness can be coordinated, and the visual quality can be improved. Further, the brightness component and the saturation component can be processed independently, and the image quality can be freely adjusted.

  According to the present embodiment, even if the luminance and the saturation are converted independently, processing without blurring is possible, so that it is possible to freely design an image without deteriorating the image quality. Further, by simultaneously converting the luminance and the saturation, not only the contrast but also the vividness are emphasized, and the image quality can be improved.

  INDUSTRIAL APPLICABILITY The display control device of the present invention can be suitably used, for example, in the field of controlling a display device of a mobile phone or an information processing terminal on which a transmission type LCD is mounted.

Block diagram of display device in Embodiment 1 of the present invention FIG. 4 is a diagram illustrating an example of conversion characteristics according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating an example of conversion characteristics according to the first embodiment of the present invention. Block diagram of a display device according to Embodiment 2 of the present invention. Explanatory drawing of a threshold value according to Embodiment 2 of the present invention. Block diagram of a display device according to Embodiment 3 of the present invention. Example diagram of weighting characteristics in Embodiment 3 of the present invention (halftone priority) FIG. 10 is a diagram illustrating an example of a weight characteristic according to the third embodiment of the present invention (low gradation priority) Block diagram of display device according to Embodiment 4 of the present invention FIG. 11 is an explanatory diagram of a table used for hue selection according to the fourth embodiment of the present invention. Block diagram of display device according to Embodiment 5 of the present invention FIG. 18 is a view showing an example of a saturation conversion characteristic according to the fifth embodiment of the present invention. Block diagram of a display device according to a first modification of the present invention. FIG. 7 is a view showing an example of conversion characteristics of a light source adjustment unit according to the first modification of the present invention. Block diagram of a display control device according to a second modification of the present invention. Block diagram of a display control device according to a third modification of the present invention.

Explanation of reference numerals

10, 30 display unit 20, 40, 50 display control device 21, 41, 52 feature amount calculation unit 22 conversion characteristic calculation unit 23 signal conversion unit 24 input terminal 25 output terminal 28 light source adjustment unit 29 storage unit 31 display device 32 light source 42 Multiplication unit 43 First output terminal 44 Second output terminal 60 Color conversion unit 61 Inverse color conversion unit 71 Luminance conversion characteristic storage unit 72 Luminance conversion unit 73 Saturation conversion characteristic storage unit 74 Saturation conversion unit 100 Division unit 101 Input selector 102 Output selector

Claims (18)

A feature value calculation unit that calculates a feature value by a predetermined calculation based on an input signal that forms the predetermined image data among image data that configures the moving image;
A conversion characteristic calculating unit that determines a position of an intermediate gradation area in the input signal, and determines a conversion characteristic of the input signal;
A display control device , comprising: a signal conversion unit configured to convert the input signal according to a determined conversion characteristic and output the converted signal . The conversion characteristic calculation unit calculates the conversion characteristic
The horizontal axis is the input signal, the vertical axis is the output signal,
A region extending from the origin to the full scale on the horizontal axis is a low gradation region near the origin, a high gradation region near the full scale, and an intermediate gradation region located between the low gradation region and the high gradation region. When divided into
The mean average slope of the gradation region, the than any of the average slope of the average slope and the high gradation region of the low gradation region shall be specified to be greater, the display control device according to claim 1. The display control device according to claim 1, wherein the conversion characteristic calculation unit determines each of the low gradation area, the high gradation area, and the halftone area by a line segment . The display control device according to claim 1, wherein the conversion characteristic calculation unit determines the low gradation area by a line segment passing through an origin . The display control device according to claim 1, wherein the conversion characteristic calculation unit determines the conversion characteristic for each of image data constituting the moving image . The display control device according to any one of claims 1 to 5, wherein the feature amount calculation unit calculates the feature amount based on a luminance component of an input signal forming predetermined image data . The display control device according to claim 6, wherein the feature amount calculation unit calculates the feature amount by averaging the luminance components . The said characteristic-value calculation part further outputs the signal which adjusts the output level of the said signal conversion part, and the light emission level of an external light source so that it may have a correlation, The one of Claim 1 to 7 characterized by the above-mentioned. Display control device. In the conversion characteristic, the maximum value of the vertical axis, when below the threshold, the feature amount calculation unit increases the output level of the signal converter, to reduce the emission level of the external source is adjusted, according to claim 8 The display control device according to the above. The display control according to any one of claims 7 to 9 , wherein when the maximum value of the conversion characteristic on the vertical axis exceeds a threshold value, the feature amount calculation unit performs adjustment so as to increase the light emission level of the external light source. apparatus. Furthermore, a light emission control signal to the output signal and an external light source to the display device based on an output signal of said signal conversion unit includes a light source adjusting part to adjust to have a correlation, any of claims 1 to 6 the display control device crab according. Further, a color conversion unit for converting the input signal from the RGB color space to another color space and separating it into a brightness component and other components is included. The display control device according to claim 1, wherein the feature amount is calculated by a predetermined calculation . 13. The display control device according to claim 12 , wherein said another color space is a color space having the same capacity for an RGB color space and a brightness component. 14. The display control device according to claim 12 , wherein the another color space is an HSV color space. 13. The display control device according to claim 12, further comprising: an inverse color conversion unit that combines the brightness component converted by the signal conversion unit and the other components, and converts the another color space to an RGB color space. . A display device, comprising: the display control device according to claim 1; and a display unit controlled by the display control device. A display control device according to claim 1 ,
A display unit,
A display device that inputs a signal whose output level has been adjusted by the signal of the conversion characteristic calculation unit of the display control device, and a light emission level is determined by a signal of the conversion characteristic calculation unit of the display control device. A light source that inputs the adjusted signal and irradiates the display device. A color conversion unit that converts an input signal from the RGB color space to another color space, and separates the input signal into a brightness component, a saturation component, and other components;
A brightness conversion unit that converts a brightness component according to a certain brightness conversion characteristic;
A saturation conversion unit that converts a saturation component according to a fixed saturation conversion characteristic;
Inverse color conversion for combining the brightness component converted by the brightness conversion unit, the saturation component converted by the saturation conversion unit, and the other components, and converting another color space to an RGB color space. Department and
The display control device, wherein the saturation conversion characteristic includes a plurality of line segments each having a predetermined inclination.