JP2007272023A - Video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of a video signal by obtaining sufficient black flotation suppression effect even in video having a black part as a half of a screen and a white part as the remaining half or on a screen on which video has information of a white character telop. <P>SOLUTION: The quantity of light irradiating an optical modulating element is controlled based upon a histogram distribution of luminance of an input video signal and darkness parameters representing degrees of darkness by luminance signal levels and when the mean value of luminance of the input video is high or when there are many dark parts causing black flotation even if a peak value is high, the quantity of light is suppressed small to suppress the black flotation, thereby outputting video having a high contrast. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video display device and a video signal processing device, and more particularly to a video display device such as a projector or a liquid crystal display having a transmissive or reflective light modulation element.

  In projectors and liquid crystal displays, there is a problem that contrast is lowered due to so-called black floating in which black floats in a dark scene. Several methods for dynamically changing the amount of light according to the scene of the video have been proposed as methods for improving the black float. For example, as a method for controlling the amount of light by the average value of the luminance of the input video, there is a projector device of Patent Document 1, and as a method for controlling by the maximum value of the luminance of the input video, for example, a projection display device of Patent Literature 2 is used. is there.

  The projector apparatus of patent document 1 is demonstrated using FIG. In FIG. 21, 211 is a light source, 212 is a light reflection element, 213 is a display panel, 214 is a lens, 215 is a luminance detection unit, 216 is a light reflection control unit, 217 is a screen, and Y1, Y2, and Y3 are optical paths. Yes. In the conventional projector apparatus, as shown in FIG. 21, a light reflection element 212 is provided on the optical path from the light source 211 to the display panel 213, and the luminance detection unit 215 detects the average value of the luminance of the input image. In the case where the average luminance value is low, the light of the optical path Y1 output from the light source 211 is reflected, and control is performed so that the amount of light of the optical path Y3 going to other than the display panel 213 increases, thereby suppressing black floating. Yes.

Further, the projection display device of Patent Document 2 includes an optical shutter that controls the amount of light, detects a peak level of an input video signal, and blocks light when the peak level is smaller than a predetermined reference level. The black float is improved.
JP 2004-29075 A JP 2001-264728 A

  In the method of controlling the amount of light with the average value of the luminance of the input video signal as in the projector device of Patent Document 1 described above, even if there are many black portions where the black float is conspicuous in the video, the white portion in the video When there is a large amount, the average luminance value becomes high, and there are cases where the effect of suppressing black float is small. For example, if half of the screen is black and the other half is white, the average value of the brightness is the median value even though there is black that makes the black float stand out. There was a case.

  Further, in the projection type display device of Patent Document 2, since the luminance of the light source is controlled by the maximum value of the luminance of the input video signal, if there is information such as white character telop in the video, it is related to the content of the video. Since the brightness level is determined to be high, the light amount control is not performed, and the black float suppression effect may not be sufficient.

  The present invention is to solve the above-described problems, and controls the amount of light applied to a light modulation element based on a histogram distribution of luminance of an input video signal and a darkness parameter representing the degree of darkness for each luminance signal level. Therefore, if the average brightness of the input video is high or if there are many black areas that cause black float even when the peak value is high, the amount of light is suppressed to suppress black float and output a high contrast video. An object of the present invention is to provide a video display device capable of performing the above.

  In order to solve the above-described conventional problems, a video display device according to the present invention is suitable for a video signal processing unit that performs gradation correction processing of contrast and luminance of a video signal, and an output of the video processing unit is suitable for light modulation. Light modulation element driving means for converting to a drive signal, light modulation element for light modulating the output of the light modulation element drive means to image light according to a video signal, and control for irradiating the light modulation element with light A brightness histogram creating means for creating a brightness histogram distribution according to the brightness level classification of the brightness signal of the video signal, and a darkness parameter for creating a darkness parameter indicating the degree of darkness according to the brightness level classification A value obtained by multiplying the brightness parameter creation means, the number of distributions for each brightness level section of the histogram distribution and the darkness parameter created for each brightness level section, for each brightness level section A light amount control data generating unit that uses the added value as a control amount; and a light source driving unit that controls the light source based on the control amount generated by the light amount control data generating unit. is there.

  Further, in the video display device of the present invention, a luminance average value calculating means for calculating an average value of the luminance of the video signal, a low-pass filter connected between the light quantity control data creating means and the light source driving means, and the luminance A scene change detection that detects a scene change from a change in luminance average value calculated by the average value calculation means, turns off the low-pass filter when a scene change is detected, and turns on the low-pass filter when no scene change is detected. Means.

  According to the video display device of the present invention, a value obtained by multiplying the number of distributions of the luminance histogram distribution of the input video signal for each luminance level category and the darkness parameter created for each luminance level category is added for each luminance level category. The amount of light that is applied to the light modulation element is controlled using the added value as the control amount, so that even if the average luminance of the input video is high or the peak value of the luminance is high, the cause of black float in the input video When there are a lot of black portions, control is performed to reduce the amount of light, so that black float can be suppressed and contrast can be improved.

  According to the video display device of the present invention, there is a scene change detecting means for detecting a scene change of the input video signal. When no scene change is detected, the light amount control amount is smoothed by the low-pass filter, and the video is displayed. Even when there is noise in the signal, the light amount of the light source can be controlled without being affected by the noise. In addition, when a scene change is detected, the low-pass filter is turned off, so that it is possible to perform light amount control in accordance with the scene change.

  Further, according to the video display device of the present invention, there is a diaphragm for controlling the amount of light between the light source and the light modulation element, and by controlling the amount of light with the diaphragm, it is possible to suppress black float and improve the contrast. In addition, it is possible to prevent deterioration of the stable lighting performance of the light source and deterioration of life characteristics.

  Further, according to the video display device of the present invention, the value obtained by multiplying the number of distributions of the luminance histogram distribution of the input video signal for each luminance level category and the darkness parameter created for each luminance level category for each luminance level category. Addition, and using the added value as the control amount, the amount of light irradiating the light modulation element is controlled by both the light source and the aperture, so the black float is suppressed by controlling the light source, the contrast is improved, and the black float is suppressed by controlling the aperture. Since the improvement in contrast is integrated, a larger improvement in image quality can be achieved.

  According to the video display device of the present invention, the gradation correction data is created by the gradation correction data creation means based on the control amount created by the light quantity control data creation means, and the video signal is generated based on the gradation correction data. Since the gradation correction is performed by the processing means, it is possible to suppress a decrease in the amount of light accompanying the light amount control, and to prevent the brightness of the intermediate luminance portion and the high luminance portion from decreasing and the contrast feeling from being lost.

  According to the video display device of the present invention, a value obtained by multiplying the number of distributions for each luminance level category of the luminance histogram of the video signal and the darkness parameter created for each luminance level category is added for each luminance level category. The first control amount for controlling the light amount of the light source is created from the obtained value, and the second control amount for controlling the light amount of the light source is created from the luminance average value of the luminance signal of the video signal, and the dynamic range of the video signal Is greater than the predetermined value, the first control amount is set to a value larger than the second control amount and added to the second control amount to obtain a control amount. When the dynamic range is smaller than the predetermined value, Even if the dynamic range of the input video signal is small and the number of luminance divisions in the histogram distribution is small, the control amount of 2 is set to a value larger than the first control amount and added to the first control amount. Light control It is possible to control the amount of source light without instability.

  According to the video display device of the present invention, when the dynamic range of the video signal is larger than a predetermined value, the first control amount is set larger than the second control amount and added to the second control amount. If the dynamic range is smaller than a predetermined value, the second control amount is set to a value larger than the first control amount and added to the first control amount to obtain the control amount. Even when the dynamic range of the video signal is small and the number of luminance divisions in the histogram distribution is small, the light quantity control amount can be controlled without causing the light quantity control amount to become unstable, and scene changes that detect scene changes in the input video signal Since the detection means and the low-pass filter are used, if a scene change is not detected, the amount of light control is smoothed by the low-pass filter, and there is noise in the video signal. It is possible to perform light quantity control of the light source without being affected by noise. In addition, when a scene change is detected, the low-pass filter is turned off, so that it is possible to perform light amount control in accordance with the scene change.

  According to the video display device of the present invention, the diaphragm for controlling the amount of light is provided between the light source and the light modulation element, and the number of distributions for each luminance level division of the luminance histogram of the video signal is created for each luminance level division. A first control amount for controlling the aperture is created from a value obtained by multiplying a value obtained by multiplying the darkness parameter for each luminance level category, and the aperture is controlled from the luminance average value of the luminance signal of the video signal. When the second control amount is created and the dynamic range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and added to the second control amount to obtain a control amount. When the range is smaller than the predetermined value, the dynamic range of the input video signal is reduced by setting the second control amount to a value greater than the first control amount and adding the first control amount to the control amount. , Brightness of histogram distribution Even if the number of divisions is small, the amount of aperture control can be controlled without instability, and the amount of light controlled by the aperture prevents deterioration of the stable lighting performance of the light source and deterioration of life characteristics. it can.

  Further, according to the video display device of the present invention, since the light source is controlled according to the dynamic range of the video signal, the control of the light source is unstable even when the dynamic range is small and the number of luminance divisions of the histogram distribution is small. The tone correction data is created by the tone correction data creation unit based on the control amount created by the light quantity control data creation unit, and the video signal processing unit is based on the tone correction data. Since gradation correction is performed, it is possible to prevent the brightness of the intermediate luminance portion and the high luminance portion from being lowered due to the light amount control and the contrast feeling being lost.

  According to the video display measure of the present invention, the dynamic range can be accurately calculated from the difference between the maximum value and the minimum value of the video signal.

  Embodiments of a video display apparatus according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a video display apparatus according to the first embodiment of the present invention. In FIG. 1, 101 is a luminance histogram creating means for creating a luminance histogram of an input video signal, 102 is a darkness parameter creating means for creating a darkness parameter representing the degree of darkness according to the brightness level classification, and 103 is a light amount control. Light quantity control data creation means for creating data, 104 a light source driving means for driving a light source by the light quantity control data, 105 a light source, 106 an optical system, 107 a light modulation element, and 108 a contrast and luminance gradation of a video signal A video signal processing unit 109 for performing correction is an optical modulation element driving unit. Examples of the light modulation element 107 include a DMD (digital micromirror device) element and a liquid crystal element. A DMD element is one in which a number of minute mirrors are arranged on a silicon-based element, and an image is generated by changing the direction of each mirror.

  The operation of the video display apparatus in the first embodiment will be described below in the case where the input video signal is 8 bits.

  The video signal input to the video display device is input to the luminance histogram creation unit 101 and the video signal processing unit 108. The video signal processing means 108 performs contrast correction and brightness correction gradation correction processing of the input video signal, and then converts it into a drive signal suitable for the light modulation action by the light modulation element driving means 109, and outputs it to the light modulation element 107. Thus, an image is displayed by being optically modulated with video light corresponding to the video signal.

  The luminance histogram creating means 101 creates a luminance histogram for each field or for each frame from the luminance signal of the input video signal. The luminance histogram represents a frequency distribution ratio for each luminance level of the input video, and for example, as shown in FIG. In FIG. 2, the horizontal axis represents the luminance level, and the vertical axis represents the frequency distribution ratio of the pixels for each luminance level. It can be seen how many pixels are distributed in the dark part by the shape of this distribution. In the case of FIG. 2, it can be seen that there are many distributions with low luminance that cause black float.

  Next, the darkness parameter creating means 102 will be described. The darkness parameter is a parameter representing the degree of darkness for each level of the input luminance signal, and takes a value as shown in FIG. 3, for example. In FIG. 3, the horizontal axis indicates the luminance level, and the vertical axis indicates the value of the darkness parameter for each luminance level. The lower the luminance level, the larger the darkness parameter, and the higher the luminance level, the smaller the darkness parameter. In the case of FIG. 3, when the luminance level is 128 or more, the luminance level is not dark, so the darkness parameter is 0. Regarding the darkness parameter, not only the characteristics shown in FIG. 3 but also parameters may be set as shown in FIG. In FIG. 4, the lower the luminance level, the larger the darkness parameter is the same as in FIG. 3, but the darkness parameter is negative when the luminance level is high. When there are many regions with high luminance in the video, the light amount control amount can be suppressed by this darkness parameter.

  Next, the light quantity control data creating unit 103 will be described. In the light quantity control data creation means 103, the number of distributions of the brightness histogram distribution created by the histogram creation means 101 for each brightness level category and the darkness parameter created for each brightness level category created by the darkness parameter creation means 102 By adding a value obtained by multiplying each luminance level category, a darkness amount that quantifies how many dark pixels and how many pixels exist is calculated. Light amount control data for controlling the light amount from the darkness amount is created.

  The amount of darkness is expressed by (Equation 1), where i is the luminance level, Xi is the distribution ratio for each luminance level, and Ki is the darkness parameter representing the degree of darkness.

  For example, when the entire screen has a luminance level of 0, that is, the entire screen is black, and the darkness parameter for each luminance level takes the value shown in FIG. When the brightness level is 0, the darkness parameter is 1.0, so the blackness amount is 100.

  Next, light quantity control data is created from the calculated darkness. An example of data creation will be described with reference to FIG. FIG. 5 shows the relationship between the amount of blackness and the amount of light. The horizontal axis represents the amount of blackness and the vertical axis represents the amount of light. Control data is created so as to reduce the amount of light as the amount of blackness increases. Therefore, for example, as described above, when the entire screen has a luminance level of 0 and the darkness parameter for each luminance level has a value as shown in FIG. 3, the darkness amount is 100, and in FIG. Since the light amount control data at that time is calculated as 0%, it is possible to express black with high dark portion contrast.

  As another example of creating light quantity control data, a case will be described in which the luminance histogram of a video signal shows a luminance distribution as shown in FIG. 2 and the darkness parameter has a value as shown in FIG. In this case, when the darkness amount is calculated by multiplying the brightness distribution and the darkness parameter and adding each brightness level division, the darkness amount is 50, and the light amount when the darkness amount is 50 in FIG. The amount of light is controlled to 50%. In the luminance histogram of FIG. 2, there is also a distribution in the high luminance portion, and the maximum luminance value is 255. Therefore, in the conventional method of controlling the luminance of the light source with the maximum luminance value, the light amount is not controlled. In the present invention, it can be seen that the amount of light is controlled in accordance with the amount of black in the image.

  In addition, when the light source is a xenon lamp or high-pressure mercury, stable lighting becomes impossible when the light quantity becomes below a certain level. Therefore, the light quantity control data may be generated so that the light is turned on at a certain level or more even when the amount of blackness is large as shown in FIG. In the case of FIG. 6, L is the minimum light quantity that the light source can be stably turned on, and the light quantity is limited so as not to become smaller than L. By doing so, the light source can be stably turned on.

  3 and 4, the relationship between the luminance level and the darkness parameter is linear, but it may be nonlinear. Similarly, in FIGS. 5 and 6, the relationship between the blackness amount and the light amount is linear, but it may be nonlinear.

  Further, as shown in FIG. 7, the light amount control data created by the light amount control data creating means may be averaged in the time axis direction by applying a low pass filter. In FIG. 7, reference numeral 112 denotes a low-pass filter. By applying a low-pass filter to the light amount control data output from the light amount control data creating means 103, the light amount of the light source can be controlled without being affected by the noise even when the video signal includes noise. Further, the scene change detection unit 111 may extract a scene change, and when there is a scene change, the low pass filter process may be turned off. If there is a scene change, the amount of light control will not change immediately if a low-pass filter is left applied to the light source control data. This may cause a delay in the light source change with respect to the screen change and adversely affect image quality. is there. Therefore, when there is a scene change, the low-pass filter process is stopped, and the light source is driven by the light amount control data created by the light amount control data creating means 103. For the scene change, an average value of the luminance of the video signal is calculated using the average luminance value calculating unit 110, and a change between the previous luminance value and the current luminance value is detected by the scene change detecting unit 111, and there is a change amount. If it is greater than the threshold, it is determined that there has been a scene change.

  Further, although the case of dynamically controlling the light source has been described with respect to the method for controlling the light amount in FIG. 1, the light amount may be controlled by means for physically controlling the light amount, such as an aperture mechanism. The configuration of the video display device in this case is shown in FIG.

  In FIG. 8, 113 is an aperture control data creating means, 114 is an aperture drive means, and 115 is an aperture means. The aperture control data creating unit 113 calculates the darkness from the brightness histogram created by the brightness histogram creating unit 101 and the darkness parameter created by the darkness parameter creating unit 102 by the method described above, and the aperture control data is created from the darkness. Create control data. The aperture control data is created so that the relationship between the darkness amount and the aperture control data is, for example, the relationship between the darkness amount and the light amount shown in FIGS. The created aperture control data is input to the aperture drive unit 114, and the aperture drive unit 114 controls the aperture of the aperture unit 115 based on the aperture control data. At this time, as described above, a low-pass filter may be applied to the aperture control data.

  Further, as shown in FIG. 9, the above-described light amount control and aperture control of the light source may be performed simultaneously. Since the black float suppression and contrast improvement by the light source control and the black float suppression and contrast improvement by the aperture control are integrated, a greater improvement in image quality can be achieved. In addition, even when the light source cannot be reduced to a certain light amount due to stable lighting, the light amount can be further reduced by using the aperture control together, so that the contrast can be further improved.

  Further, as shown in FIG. 10, gradation correction may be performed according to the light amount control data output from the light amount control data creating unit 103. When the amount of light is controlled in accordance with the input image and the amount of light from the light source is decreased, the luminance of the portion with high luminance may decrease and the contrast may be lost. Therefore, the gradation is corrected in accordance with the light amount control amount of the light source to prevent the contrast from being lowered.

  In FIG. 10, reference numeral 116 denotes gradation correction data creating means, which creates gradation correction data based on the light amount control data created by the light amount control data creating means 103, and stores it in the video signal processing device 108 based on the data. To correct the gradation. A method of creating gradation correction data in this case will be described with reference to FIG.

  In FIG. 11, the solid line denoted as “light quantity MAX” represents the gradation characteristic when the light quantity control is not performed, that is, when the light quantity is maximum, and the output is output as it is with respect to the input. It has become. A solid line described as “when the light amount is MIN” represents a gradation characteristic when the light amount control amount is maximum, that is, when the light amount is minimum, and is a gradation characteristic that corrects a decrease in luminance. A dotted line written as “light quantity X” represents an input / output characteristic of the gradation correction amount when the light quantity of the light quantity control data created by the light quantity control data creation unit 103 is X. The light quantity X is a value between the light quantity MIN and the light quantity MAX.

  If the gradation correction amount when the light amount is X is C, the light amount when the light amount is MAX is L_MAX, the gradation correction amount at that time is A, the light amount when the light amount is MIN is L_MIN, and the gradation correction at that time When the amount is B, the gradation correction amount C is expressed by (Equation 2).

  In this way, since the video signal processing means performs gradation correction based on the light amount control amount, it is possible to prevent the brightness of the intermediate luminance portion and the high luminance portion from being lowered due to the light amount control, thereby eliminating the feeling of contrast.

  Note that the input / output characteristics of the gradation correction amount are not limited to those shown in FIG. 11, but may be those shown in FIGS. 12A and 12B, for example. FIG. 12A shows gradation characteristics in which the slope of the input / output relationship is changed between the light amount MIN and the light amount MAX, and it is possible to correct a decrease in luminance of the high luminance portion.

  In the case of FIG. 12B, the gradation characteristics are not changed between the light intensity MAX and the light intensity MIN in the low luminance part, and the output characteristics at the light intensity MIN increase from the intermediate luminance part to the high luminance part. It has the following characteristics. With such characteristics, it is possible to suppress black float in the low-brightness part, and it is possible to suppress a decrease in contrast by increasing the gradation of the middle and high-brightness parts.

  As described above, in the first embodiment, the luminance level division is obtained by multiplying the number of distributions of the luminance histogram distribution of the input video signal for each luminance level division and the darkness parameter created for each luminance level division. In order to control the amount of light that is applied to the light modulation element using the added value as a control amount, black is not included in the input video even when the average luminance of the input video is high or the peak luminance is high. When there are many black portions that cause floating, control is performed to reduce the amount of light, so that black floating can be suppressed and contrast can be improved.

  In the first embodiment, the scene change detecting means and the low-pass filter for smoothing the light amount control amount are provided. If no scene change is detected, the light amount control amount is smoothed by the low-pass filter. Even if there is noise in the video signal, the light quantity control of the light source is performed without being affected by the noise, and when a scene change is detected, the low-pass filter is turned off to control the light quantity according to the scene change. be able to.

  In the first embodiment, since the diaphragm for controlling the amount of light is provided, the amount of light can be controlled by the diaphragm to suppress the black float and improve the contrast. It is possible to prevent deterioration and deterioration of life characteristics.

  In the first embodiment, since the amount of light applied to the light modulation element is controlled by both the light source and the diaphragm, the black float is suppressed by controlling the light source, the contrast is improved, the black float is suppressed by controlling the diaphragm, and the contrast is controlled. Since the improvements are accumulated, it is possible to improve the image quality more greatly.

  In the first embodiment, since the video signal processing means performs gradation correction based on the control amount of the light amount, the light amount decrease due to the light amount control is suppressed, and the luminance of the intermediate luminance portion and the high luminance portion is reduced. To prevent the contrast from being lost.

  FIG. 13 is a block diagram showing the configuration of the video display apparatus according to Embodiment 2 of the present invention. In FIG. 13, 117 is a first light quantity control data creating means, 118 is a second light quantity control means, 119 is a luminance maximum value calculating means, 120 is a luminance minimum value calculating means, and 121 is a dynamic range calculating means.

  In the second embodiment, as shown in FIG. 14A, when the difference between the maximum value and the minimum value of the luminance level is not so much, the dynamic range of the video signal is small, and the number of luminance level sections of the luminance histogram is small. An image display apparatus capable of performing effective light amount control will be described.

  When the luminance histogram of the video signal is shown in FIG. 14A, the luminance histogram when the luminance level division is 8 is as shown in FIG. As described above, when the dynamic range of the video signal is small and the number of luminance level divisions in the luminance histogram is small, the luminance level of the video signal gradually changes and the luminance distribution moves across the boundaries of the luminance level divisions. Sometimes, the number of distributions for each luminance category changes abruptly, so that the light amount control amount calculated from the luminance histogram and the darkness parameter changes abruptly, which may adversely affect image quality.

  Therefore, the first light amount control data is created from the luminance histogram and the darkness parameter by the above-described method, the second light amount control data is created by calculating the light amount control amount from the average value of the luminance, and the dynamics of the input video signal. When the range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and added to the second control amount to obtain a control amount, and the dynamic range is less than the predetermined value. If it is smaller, the second control amount is set to a value larger than the first control amount and added to the first control amount to obtain the control amount, so that the dynamics of the video signal as shown in FIG. When the range is small, the second control amount calculated by the average value of the luminance is the main control amount, so that it is possible to prevent the light amount control amount from changing abruptly.

  The dynamic range is calculated by the dynamic range calculator 121 from the difference between the maximum value and the minimum value by calculating the maximum value and the minimum value of the brightness level from the maximum brightness value calculator 119 and the minimum brightness value calculator 120.

  A series of these operations will be described with reference to the flowchart of FIG. First, a video signal is input (S01), and a luminance histogram of the video signal is calculated (S02). Next, the darkness parameter is calculated (S03). First light quantity control data is calculated from the calculated luminance histogram and darkness parameter by the method described above (S04). Next, an average value of luminance is calculated (S05), and second light quantity control data is calculated from the average value of luminance (S06). As a method for calculating the light amount control amount from the average value of luminance, for example, as shown in FIG. 16, when the average luminance value is low, the light amount is decreased, and as the average luminance value increases, the light amount is increased. Also good. In FIG. 16, L on the vertical axis indicates the minimum amount of light that the light source can stably emit, and in the case of a light source such as an LED, L = 0 can also be set. In this way, second light quantity control data is created from the average value of luminance.

  Next, the maximum value and the minimum value of luminance are calculated (S07, S08), and the dynamic range is calculated from the difference between the maximum value and the minimum value (S09). When the dynamic range is large, the ratio of the first light quantity control data calculated from the luminance histogram and the darkness parameter is increased, and the ratio of the second light quantity control data calculated from the average value of the luminance is reduced to be combined. If the composite ratio of the two data is calculated and the dynamic range is small, the ratio of the first light quantity control data calculated from the luminance histogram and the darkness parameter is decreased, and the first calculated from the average value of the luminance is calculated. The synthesis ratio is calculated so that the ratio of the light quantity control data 2 is increased (S10). An example of the calculated composition ratio is shown in FIG. In FIG. 17, the composition ratio of the first light quantity control data increases as the dynamic range increases, and conversely, the second light quantity control data calculated from the average luminance value decreases as the dynamic range increases. . Thereafter, the light amount control amount is calculated from the first light amount control data and the second light amount control data based on the combination ratio (S11), and the value is input to the light source driving means 104 to control the light source 105. By calculating the light amount control amount in this way, when the dynamic range is large, accurate light amount control can be performed according to the frequency distribution of the low luminance portion of the luminance histogram, and when the dynamic range is small. Since the light amount control is performed mainly with the control amount calculated from the average value of the luminance, it is possible to prevent the light amount light amount control amount from changing suddenly.

  Further, as in the first embodiment, the light amount control data created by the light amount control data creating means may be averaged in the time axis direction by applying a low pass filter. The configuration of the video display apparatus in this case is shown in FIG. The luminance average value is calculated by the luminance average value calculating means 110, a scene change is determined based on a change in the average luminance value, and if there is a scene change, the low pass filter process is stopped. By applying a low-pass filter in the time axis direction, the light quantity of the light source can be controlled without being affected by noise even when there is noise in the image.

  Further, similarly to the first embodiment, the light amount may be controlled by means for physically controlling the light amount, such as a diaphragm mechanism. The configuration of the video display device in this case is shown in FIG. From the brightness histogram created by the brightness histogram creating means 101 and the darkness parameter created by the darkness parameter creating means 102, the first aperture control data creating means 122 creates first aperture control data. Next, the second aperture control data creating unit 123 creates second aperture control data from the average brightness value calculated by the brightness average value calculating unit 110. The dynamic range is calculated by the dynamic range calculation means 121 from the maximum value and the minimum value of the luminance. As shown in FIG. 17, when the dynamic range is large, the first aperture calculated from the luminance histogram and the darkness parameter. Aperture control data is created by the aperture control data creating means 113 based on a value obtained by combining the control data with the ratio of the second aperture control data calculated from the average value of brightness increased and the dynamic range. Is small, the ratio of the first aperture control data calculated from the brightness histogram and the darkness parameter is decreased, and the ratio of the second aperture control data calculated from the average value of the brightness is increased to obtain a composite value. Aperture control data is created, and the aperture drive means 114 controls the aperture means 115.

  Further, as in the first embodiment, gradation correction may be performed according to the light amount control amount of the light source. The configuration of the video display device in this case is shown in FIG. The dynamic range is calculated by the dynamic range calculation means 121 from the maximum luminance value and the minimum luminance value, and is calculated from the first light quantity control data calculated from the luminance histogram and the darkness parameter according to the dynamic range and the average luminance value. The light quantity control data is generated by the light quantity control data creating means 103 by combining the second light quantity control data. From the light amount control data, the light source driving unit 104 drives the light source, and at the same time, the tone correction data creating unit 116 creates tone correction data, and the video signal processing unit 108 performs tone correction. As described above, the gradation correction data is generated from the light amount control data by using the gradation correction amounts at the time of the light amount MAX and the light amount MIN. By performing gradation correction according to the light amount of the light source, it is possible to suppress the brightness of the high-brightness portion from being lowered, and thus it is possible to prevent the contrast from being lowered.

  As described above, in the second embodiment, the first light quantity control data is created from the brightness histogram and the darkness parameter, and the second light quantity control data calculated from the average value of the brightness is created. Depending on the size of the range, by creating light amount control data mainly from the first light amount control data when the dynamic range is large, and mainly from the second light amount control data when the dynamic range is small, When the dynamic range is small, the light amount is controlled mainly from the average value of luminance, and it is possible to prevent the light amount control amount from changing rapidly.

  As described above, in the second embodiment, a value obtained by multiplying the number of distributions for each luminance level category of the luminance histogram of the video signal by the darkness parameter created for each luminance level category is assigned to each luminance level category. A first control amount for controlling the light amount of the light source is created from the value added to the above, and a second control amount for controlling the light amount of the light source is created from the luminance average value of the luminance signal of the video signal. When the dynamic range is larger than a predetermined value, the first control amount is larger than the second control amount and added to the second control amount to obtain a control amount. When the dynamic range is smaller than the predetermined value, By setting the second control amount to a value larger than the first control amount and adding it to the first control amount to obtain the control amount, the dynamic range of the input video signal is small and the number of luminance divisions of the histogram distribution is small. Even if light Control amount can be controlled amount of source light without becoming unstable.

  Further, the second embodiment has a scene change detecting means and a low-pass filter for smoothing the light amount control amount. When no scene change is detected, the light amount control amount is smoothed by the low-pass filter. Even if there is noise in the video signal, the light quantity control of the light source is performed without being affected by the noise, and when a scene change is detected, the low-pass filter is turned off to control the light quantity according to the scene change. be able to.

  In the second embodiment, since the diaphragm for controlling the amount of light is provided, the amount of light can be controlled by the diaphragm to suppress black float and improve the contrast, and the stable lighting performance of the light source. It is possible to prevent deterioration and deterioration of life characteristics.

  In the second embodiment, gradation correction is performed by the video signal processing unit in accordance with the control amount of the light amount. Therefore, a decrease in the light amount due to the light amount control is suppressed, and the luminance of the intermediate luminance portion and the high luminance portion is reduced. To prevent the contrast from being lost.

  In the second embodiment, the dynamic range can be accurately calculated from the difference between the maximum value and the minimum value of the video signal.

  The video display device according to the present invention controls the amount of light applied to the light modulation element based on the histogram distribution of the luminance of the input video signal and the darkness parameter indicating the degree of darkness for each luminance signal level. When the average luminance value is high or the peak value is high, the amount of light can be suppressed when there are many black parts that cause black floats, which is useful for improving the contrast of the image. .

Block diagram of a video display device in Embodiment 1 of the present invention The figure showing the brightness | luminance histogram in Embodiment 1 of this invention Explanatory drawing of the darkness parameter in Embodiment 1 of this invention Explanatory drawing of the darkness parameter in Embodiment 1 of this invention Relationship diagram between darkness and light quantity in Embodiment 1 of the present invention Relationship diagram between darkness and light quantity in Embodiment 1 of the present invention Block diagram of a video display device in Embodiment 1 of the present invention Block diagram of a video display device in Embodiment 1 of the present invention Block diagram of a video display device in Embodiment 1 of the present invention Block diagram of a video display device in Embodiment 1 of the present invention Explanatory drawing of the gradation correction amount in Embodiment 1 of the present invention Explanatory drawing of the gradation correction amount in Embodiment 1 of the present invention Block diagram of a video display apparatus according to Embodiment 2 of the present invention The figure showing the brightness | luminance histogram in Embodiment 2 of this invention Processing flowchart of video display device in embodiment 2 of the present invention FIG. 7 is a relationship diagram between the average luminance value and the light amount according to Embodiment 2 of the present invention. Explanatory drawing of the light quantity control amount in Embodiment 2 of this invention Block diagram of a video display apparatus according to Embodiment 2 of the present invention Block diagram of a video display apparatus according to Embodiment 2 of the present invention Block diagram of a video display apparatus according to Embodiment 2 of the present invention Block diagram of a conventional projector device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Luminance histogram creation means 102 Darkness parameter creation means 103 Light quantity control data creation means 104 Light source drive means 105 Light source 106 Optical system 107 Light modulation element 108 Video signal processing means 109 Light modulation element drive means 110 Luminance average value calculation means 111 Scene change Detection means 112 Low-pass filter 113 Aperture control data creation means 114 Aperture drive means 115 Aperture means 116 Tone correction data creation means 117 First light quantity control data creation means 118 Second light quantity control data creation means 119 Brightness maximum value calculation means 120 Minimum brightness value calculation means 121 Dynamic range calculation means 122 First aperture control data creation means 123 Second aperture control data creation means 211 Light source 212 Light reflection element 213 Display panel 214 Lens 215 Luminance detection Unit 216 light reflection control unit 217 screen

Claims (10)

Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter indicating the degree of darkness according to the brightness level classification;
A light amount control data creating means having a control amount as a value obtained by adding a value obtained by multiplying the number of distributions for each brightness level section of the histogram distribution and a darkness parameter created for each brightness level section for each brightness level section;
And a light source driving unit configured to control the light source based on the control amount created by the light amount control data creating unit. A luminance average value calculating means for calculating an average luminance value of the video signal;
A low pass filter connected between the light quantity control data creating means and the light source driving means;
A scene in which a change in the scene is detected from a change in the average brightness value calculated by the average brightness value calculation means, and when the change in the scene is detected, the low-pass filter is turned off, and when no scene change is detected, the scene in which the low-pass filter is turned on The video display device according to claim 1, further comprising a change detection unit. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A light source for irradiating the light modulation element with light;
Controllable diaphragm means provided between the light source and the light modulation element;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter representing the degree of darkness according to the brightness level classification;
Aperture control data creating means using as a control amount a value obtained by adding a value obtained by multiplying the number of distributions for each brightness level section of the histogram distribution and a darkness parameter created for each brightness level section, for each brightness level section;
An image display device comprising: aperture driving means for controlling the aperture means based on the control amount created by the aperture control data creating means. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
Controllable diaphragm means provided between the light source and the light modulation element;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter representing the degree of darkness according to the brightness level classification;
Aperture control data creating means using as a control amount a value obtained by adding a value obtained by multiplying the number of distributions for each brightness level section of the histogram distribution and a darkness parameter created for each brightness level section, for each brightness level section;
A light amount control data creating means having a control amount as a value obtained by adding a value obtained by multiplying the number of distributions for each brightness level section of the histogram distribution and a darkness parameter created for each brightness level section for each brightness level section;
Aperture driving means for controlling the aperture means based on the control amount created by the aperture control data creating means;
And a light source driving unit configured to control the light source based on the control amount created by the light amount control data creating unit. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter indicating the degree of darkness according to the brightness level classification;
A light amount control data creating means having a control amount as a value obtained by adding a value obtained by multiplying the number of distributions for each brightness level section of the histogram distribution and a darkness parameter created for each brightness level section for each brightness level section;
Gradation correction data creating means for creating gradation correction data of the video signal processing means based on the control amount created by the light quantity control data creating means;
And a light source driving unit configured to control the light source based on the control amount created by the light amount control data creating unit. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter indicating the degree of darkness according to the brightness level classification;
A first control for controlling the light amount of the light source by adding a value obtained by multiplying the number of distributions for each luminance level category of the histogram distribution and a darkness parameter created for each luminance level category for each luminance level category. First light quantity control data creating means for making a quantity;
Dynamic range calculating means for calculating a dynamic range of the video signal;
A luminance average value calculating means for calculating a luminance average value of the luminance signal of the video signal;
Second light quantity control data creating means for creating a second control amount for controlling the light quantity of the light source from the luminance average value;
When the dynamic range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and is added to the second control amount to obtain a control amount. If the value is smaller than the value, the second control amount is set to a value larger than the first control amount and added to the first control amount to obtain a light amount control data creating means,
And a light source driving unit configured to control the light source based on the control amount created by the light amount control data creating unit. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter indicating the degree of darkness according to the brightness level classification;
A first control for controlling the light amount of the light source by adding a value obtained by multiplying the number of distributions for each luminance level category of the histogram distribution and a darkness parameter created for each luminance level category for each luminance level category. First light quantity control data creating means for making a quantity;
Dynamic range calculating means for calculating a dynamic range of the video signal;
A luminance average value calculating means for calculating a luminance average value of the luminance signal of the video signal;
Second light quantity control data creating means for creating a second control amount for controlling the light quantity of the light source from the luminance average value;
When the dynamic range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and is added to the second control amount to obtain a control amount. If the value is smaller than the value, the second control amount is set to a value larger than the first control amount and added to the first control amount to obtain a light amount control data creating means,
A low pass filter connected between the light quantity control data creating means and the light source driving means;
A scene in which a change in the scene is detected from a change in the average brightness value calculated by the average brightness value calculation means, and when the change in the scene is detected, the low-pass filter is turned off, and when no scene change is detected, the scene in which the low-pass filter is turned on Change detection means;
And a light source driving unit configured to control the light source based on an output of the low-pass filter. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A light source for irradiating the light modulation element with light;
Controllable diaphragm means provided between the light source and the light modulation element;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter representing the degree of darkness according to the brightness level classification;
A first control amount for controlling the aperture by adding a value obtained by multiplying the number of distributions for each luminance level category of the histogram distribution and a darkness parameter created for each luminance level category for each luminance level category; First aperture control amount data creating means,
Dynamic range calculating means for calculating a dynamic range of the video signal;
A luminance average value calculating means for calculating a luminance average value of the luminance signal of the video signal;
Second aperture control data creating means for creating a second control amount for controlling the aperture from the brightness average value;
When the dynamic range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and is added to the second control amount to obtain a control amount. If the value is smaller than the value, aperture control data creating means for setting the second control amount to a value larger than the first control amount and adding the first control amount to the first control amount;
An image display device comprising: aperture driving means for controlling the aperture means based on the control amount created by the aperture control data creating means. Video signal processing means for performing gradation correction processing of contrast and luminance of the video signal;
A light modulation element driving means for converting the output of the video processing means into a drive signal suitable for a light modulation action;
A light modulation element for optically modulating the output of the light modulation element driving means into video light corresponding to a video signal;
A controllable light source for irradiating the light modulation element with light;
A luminance histogram creating means for creating a luminance histogram distribution in accordance with the luminance level classification of the luminance signal of the video signal;
Darkness parameter creating means for creating a darkness parameter indicating the degree of darkness according to the brightness level classification;
A first control for controlling the light amount of the light source by adding a value obtained by multiplying the number of distributions for each luminance level category of the histogram distribution and a darkness parameter created for each luminance level category for each luminance level category. First light quantity control data creating means for making a quantity;
Dynamic range calculating means for calculating a dynamic range of the video signal;
A luminance average value calculating means for calculating a luminance average value of the luminance signal of the video signal;
Second light quantity control data creating means for creating a second control amount for controlling the light quantity of the light source from the luminance average value;
When the dynamic range is larger than a predetermined value, the first control amount is set to a value larger than the second control amount and added to the second control amount to obtain a control amount. If the value is smaller than the value, the second control amount is set to a value larger than the first control amount and added to the first control amount to obtain a light amount control data creating unit;
Gradation correction data creating means for creating gradation correction data of the video signal processing means based on the control amount created by the light quantity control data creating means;
And a light source driving unit configured to control the light source based on the control amount created by the light amount control data creating unit. The dynamic range calculating means includes a luminance maximum value calculating means for calculating the maximum luminance value of the video signal, and a luminance minimum value calculating means for calculating the minimum luminance value of the video signal. The video display device according to claim 6, wherein the difference between the minimum luminance values is a dynamic range.

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