JP2013225074A - Image display device and image display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device and an image display method that can reduce power while suppressing image quality deterioration.SOLUTION: An image display device performs gradation display by dividing a field image into multiple binary sub-field images with luminance weighted and by temporally overlapping the sub-field images with one another, and includes an address data processing circuit 60 that generates address data corresponding to the sub-field images. The address data processing circuit includes: smoothing means 61 that, in at least one of the sub-field images, applies smoothing to areas with many changes in the address data; and smoothing suppression means 62 that suppresses the smoothing in areas with gentle changes in luminance of at least one of the sub-field images.

Description

  The present invention relates to an image display device and an image display method.

  Conventionally, a plasma display device is known as one of image display devices. FIG. 1 is a diagram showing an example of a plasma display panel (hereinafter referred to as “PDP”) 30 of a plasma display device that has been conventionally used. As shown in FIG. 1, the PDP 30 is configured such that the front plate 10 and the back plate 20 face each other. The front plate 10 includes a scan electrode 12 and a sustain electrode 13 arranged in parallel to each other on the surface of the front glass substrate 11, and the dielectric layer 14 and the protective layer 15 cover the scan electrode 12 and the sustain electrode 13. Composed.

  Further, the back plate 20 is disposed on the back glass substrate 21 so that the data electrodes 22 are orthogonal to the scan electrodes 12 and the sustain electrodes 13, and the red, green, and blue phosphors 23R, 23G, 23B is configured to cover. A partition wall 24 is formed at the boundary between the phosphors 23R, 23G, and 23B. A light emitting cell is formed at the intersection of the scan electrode 12, the sustain electrode 13 and the data electrode 22.

  FIG. 2 is a diagram showing an example of the overall configuration of a conventional plasma display apparatus. As shown in FIG. 2, the plasma display device includes a video data processing circuit 40 for processing video signals, a scan electrode driving circuit 80 for applying pulse voltages to the scan electrodes 12, the sustain electrodes 13, and the data electrodes 22, respectively. A sustain electrode driving circuit 90 and a data electrode driving circuit 70 are provided. A video data processing circuit 40 for processing video signals, a control signal generation circuit 50 for generating control signals, and an address data processing circuit 160 for processing address data are provided. The video data signal is sent to the address data processing circuit 160, and the address selection of the light emitting cell to be lit is performed by the data electrode driving circuit 70. The drive of each electrode 12, 13, 22 is controlled by the input of the synchronization signal. The signal generation circuit 50 performs the synchronization.

  The plasma display apparatus is driven by a subfield method. The subfield method is known as a technique for displaying intermediate gradations on a display device that displays a binary image.

  FIG. 3 is a diagram showing an example of the subfield method. In the sub-field method, as shown in FIG. 3, for example, when the input image is 8-bit data, it is divided into 8 sub-fields having a power of power of 2, and these are overlapped so that an intermediate gradation is obtained. Express. One subfield includes an address discharge period Ta and a sustain discharge period Ts. Address selection is performed in the address discharge period Ta, and a predetermined number of sustain discharges corresponding to the weight of each subfield are performed in the sustain discharge period Ts. Do.

  FIG. 4 is a diagram showing an example of a voltage pulse applied to each electrode in the subfield method. As shown in FIG. 4, whether or not the scan pulse Psca is sequentially applied to the scan electrode 12 from the first row in each subfield and the data pulse Pd is output to the data electrode 22 at the timing when the scan pulse Psca is applied. Then, the address data is written. Subsequently, the sustain pulse Psus is alternately applied to the sustain electrode 13 and the scan electrode 12, and light is emitted by the number of times of the sustain pulse Psus in the light emitting cell in which writing has been performed. Since the number of sustain pulses Psus in each subfield is set to a number proportional to a power of 2, a moving image having a halftone is displayed by temporally superposing eight subfield images. The

  Incidentally, there is a capacitive structure made of a dielectric between the electrodes 12, 13, and 22 of the PDP 30, and the loads of the drive circuits 70, 80, and 90 are capacitive loads. When writing address data, power is consumed when the data pulse Pd changes from low to high or from high to low. As the transition of the data pulse Pd increases like a checkered pattern, the power consumption increases. When the display device is increased in size and definition, the load capacity increases and the number of pixels increases, so the number of transitions of the data pulse Pd also increases and the power loss also increases. In the plasma display device using the subfield method, it becomes a problem to reduce the power loss at the time of such data pulse Pd transition.

  To solve this problem, there has been proposed a method of reducing power consumption by reducing the number of data pulse transitions by applying a spatial filter to a binary subfield image and smoothing the image (see, for example, Patent Document 1). ).

JP 2000-347620 A

  However, in the method described in Patent Document 1 described above, the image quality degradation is not so noticeable in a region where the spatial frequency of the image is high, but the image quality degradation is easily recognized in a region where the luminance change is gentle. In particular, when this method is applied to a subfield image having a large luminance weight, there is a problem that image quality deterioration becomes remarkable.

  SUMMARY An advantage of some aspects of the invention is that it provides an image display apparatus and an image display method capable of reducing power consumption while suppressing image quality deterioration.

In order to achieve the above object, an image display device according to an aspect of the present invention divides a field image into a plurality of binary subfield images weighted to luminance, and superimposes the subfield images temporally. An image display device that performs gradation display with
An address data processing circuit for generating address data corresponding to the subfield image;
The address data processing circuit comprises: smoothing means for smoothing a region where changes in address data are dense in at least one of the subfield images;
Smoothing suppression means for suppressing the smoothing in a region where the luminance change of the at least one subfield image is gentle.

  According to the present invention, power consumption can be reduced while image quality deterioration is suppressed.

It is the figure which showed an example of the plasma display panel used conventionally. It is the figure which showed an example of the whole structure of the conventional plasma display apparatus. It is the figure which showed an example of the subfield method. It is the figure which showed an example of the voltage pulse applied to each electrode in a subfield method. 1 is an overall configuration diagram illustrating an example of a plasma display device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating an example of a processing flow of an image processing method using the image display device according to the first embodiment. It is the figure which showed an example of the input field image. It is the figure which showed the 5th subfield image of the input image. It is the figure which showed the 5th subfield image after an opening process. It is the figure which showed the top hat image obtained by the top hat process. It is the figure which showed the top hat image which deleted the data of the low frequency area | region. It is the figure which showed the last 5th subfield image. It is the figure which showed the output image when not performing the process of a low frequency area | region, and when it performs. FIG. 13A is an output image of the image display device according to the comparative example when the low frequency region processing is not performed. FIG. 13B is an output image of the image display apparatus according to the first embodiment when processing in the low frequency region is performed. FIG. 13C is an enlarged view of an area A of the output image of the image display device according to the comparative example shown in FIG. FIG. 13D is an enlarged view of a region A of the output image of the image display apparatus according to Embodiment 1 shown in FIG. FIG. 13E is an enlarged view of a region A at the same location of the input image. 4 is a table showing the number of transitions of data pulses of subfield image data and input subfield image data subjected to image display processing by the image display apparatus according to the first embodiment. 6 is a diagram illustrating an example of a processing flow of an image processing apparatus and an image processing method according to Embodiment 2. FIG. It is the figure which showed an example of the 1 field image of the color image input. It is the figure which showed the color top hat image which deleted the data of the low frequency area | region. FIG. 17A is a diagram showing a top signal image of a red signal from which data in the low frequency region is deleted. FIG. 17B is a diagram showing a top hat image of a green signal from which data in the low frequency region is deleted. FIG. 17C is a diagram illustrating a top hat image of a green signal from which data in the low frequency region is deleted. It is the table | surface which showed the frequency | count of transition of the data pulse potential of the subfield image data which performed the image display process by the image display apparatus which concerns on Embodiment 2 of this invention, and input subfield image data.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

Embodiment 1
FIG. 5 is an overall configuration diagram showing an example of an image display apparatus according to Embodiment 1 of the present invention. In the first embodiment, an example in which the image display device is configured as a plasma display device will be described. 5, the image display apparatus according to the present embodiment includes a PDP 30, a video data processing circuit 40, a control signal generation circuit 50, an address data processing circuit 60, a data electrode driving circuit 70, and a scanning electrode driving circuit 80. And a sustain electrode drive circuit 90. The PDP 30 includes the scan electrode 12, the sustain electrode 13, and the data electrode 22. Here, the constituent elements other than the address data processing circuit 60 are the same as the constituent elements shown in FIGS.

  The address data processing circuit 60 includes a smoothing filter 61 and a smoothing suppression filter 62. The smoothing suppression filter 62 includes a top hat processing unit 63, a spatial frequency determination unit 64, and a suppression unit 65.

  The smoothing filter 61 is a spatial filter that performs a smoothing process, and specifically performs an opening process or a closing process. The smoothing process is a process of averaging the luminance values using the luminance values around the target pixel. The contents of the opening process and the closing process will be described later.

  The smoothing suppression filter 62 is a spatial filter for suppressing the smoothing process performed by the smoothing filter. The smoothing suppression filter 62 includes a top hat processing unit 63, a spatial frequency determination unit 64, and a suppression unit 65.

  The top hat processing unit 63 is a unit that obtains a top hat image by taking the difference between the image data obtained by the smoothing process of the smoothing filter 61 and the image data before the smoothing process.

  The spatial frequency determination unit 64 is a unit that determines whether or not the target pixel is included in the low frequency region. The specific processing content of the spatial frequency determination means 64 will be described later.

  The suppression unit 65 is a unit that performs a process of canceling the smoothing process received by the smoothing filter 61 on the pixels that are determined to be included in the low frequency region by the spatial frequency determination unit 64. Thereby, the smoothing process by the smoothing filter 61 is suppressed.

  Note that the smoothing filter 61, the smoothing suppression filter 62, and the top hat processing unit 63, the spatial frequency determination unit 64, and the suppression unit 65 included in the smoothing suppression filter 62 perform various arithmetic processes, and thus have a specific application. For example, an ASIC (Application Specific Integrated Circuit) designed for this purpose, a CPU (Central Processing Unit), and a microcomputer that operates according to a program may be included.

  FIG. 6 is a diagram illustrating an example of a processing flow of an image processing method using the image display apparatus according to the first embodiment of the present invention. More specifically, FIG. 6 shows a flow from processing the input monochrome image data of (vertical 165 × horizontal 202) pixels to outputting it to the data electrode driving circuit. In the first embodiment, the operation of the image display apparatus will be described by taking as an example a case where a one-field image of an 8-bit monochrome image is input. In addition, about the component similar to the component demonstrated until now, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  In FIG. 6, in step S100, 8-bit monochrome image data is input as one field image. The field image is input to the video data processing circuit 40.

  FIG. 7 is a diagram illustrating an example of a field image input to the video data processing circuit 40. Hereinafter, the operation of the image display apparatus according to the present embodiment will be described using an example in which the field image shown in FIG. 7 is input. As shown in FIG. 7, the input field image is an image in which leaves and artifacts are reflected.

  Returning to FIG. In step S110, the one-field image input to the video data processing circuit 40 is converted into eight subfield images from first to eighth. Such subfield conversion may be performed by the video data processing circuit 40.

Each subfield image data is composed of binary signals of “1” or “0”. The luminance weight of the first subfield image is 2 ⁰ = 1, the luminance weight of the second subfield image is 2 ¹ = 2, the luminance weight of the third subfield image is 2 ² = 4, and the fourth subfield The luminance weight of the image is 2 ³ = 8, the luminance weight of the fifth subfield image is 2 ⁴ = 16, the luminance weight of the sixth subfield image is 2 ⁵ = 32, and the luminance weight of the seventh subfield image is Let 2 ⁶ = 64 and the luminance weight of the eighth subfield image be 2 ⁷ = 128. The sustain electrode driving circuit 90 and the scan electrode driving circuit 80 output the number of sustain pulses Psus proportional to the luminance weight of each subfield image, and only the pixels for which the address data has been written emit light. By continuously displaying the subfield images, an image having a halftone of 256 gradations can be displayed.

  FIG. 8 is a diagram showing a fifth subfield image of the input image. As shown in FIG. 7, the fifth subfield image is represented by a binary image. In the present embodiment, an example in which smoothing processing and smoothing suppression processing are performed on the fifth subfield image will be described.

  Returning to FIG. 6, in step S120, the fifth subfield image data shown in FIG. 8 is subjected to an opening process to perform a smoothing process. The smoothing process is performed by the smoothing filter 61.

  The opening process includes a contraction process performed first and an expansion process performed after the contraction process. The contraction process is a process of replacing the target pixel with black if there is even one black around the target pixel. On the contrary, the expansion process is a process of replacing the target pixel with white if there is even one white around the target pixel. In the contraction process and the expansion process in the present embodiment, calculation is performed for three pixels obtained by adding the pixel before and after the data electrode 22 in common to the target pixel to be processed. In the contraction process, when white is set to “1” and black is set to “0”, if the sum of data of 3 pixels is 2 or less, the value of the pixel to be processed is set to “0”, and otherwise, “1”. And That is, if all three pixels are “1”, it is “1”, but otherwise “0”. In the expansion process, the value of the processing target pixel is set to “1” if the sum of the data of the three pixels is 1 or more, and “0” otherwise. That is, if even one of the three pixels is “1”, it is “1”, and when all three pixels are “0”, it is “0”.

  FIG. 9 is a diagram showing a fifth subfield image after the opening process. As shown in FIG. 9, the fifth subfield image after the opening process has more blackened areas than the subfield image before the opening process shown in FIG. 8. That is, it is shown that the area converted from “1” to “0” is increased by the opening process.

  Returning to FIG. 6, in step S130, a top hat process is performed. The top hat processing is performed by the top hat processing means 63 of the smoothing suppression filter 62. The top hat process is performed by taking a difference between the image data of the subfield image before the opening process shown in FIG. 8 and the image data of the subfield image after the opening process shown in FIG.

  FIG. 10 is a diagram showing a top hat image obtained by the top hat processing performed in step S130. In the top hat process, the difference between the subfield image before the opening process and the subfield image after the opening process is taken. Therefore, when the image after the opening process is subtracted from the image before the opening process, the white “1” The portion is a portion where 1-0 = 1, and is a portion changed from white to black by the opening process.

  Returning to FIG. 6, in step S <b> 140, the spatial frequency determination process of the original fifth subfield image is performed on the top hat image illustrated in FIG. 10, and the processing target pixel (target pixel) is placed in the low frequency region. It is determined whether or not there is. The spatial frequency determination process is performed by the spatial frequency determination means 64. Here, since the low frequency region is a region where the luminance change between “1” and “0” is small, it means a region where the luminance change is gentle.

  When it is determined that the processing target pixel is in the low frequency region, the process proceeds to step S150, and processing for excluding the processing target pixel from the image data of the top hat image is performed. Thereby, in the low frequency region, the white “1” portion of the top hat image is deleted, and the conversion process from white to black by the opening process is suppressed. Note that the low-frequency region data is excluded from the top hat image by the suppression unit 65. After step S150, the process proceeds to step S160.

  On the other hand, if it is determined in step S140 that the processing target pixel is not in the low frequency region, the process proceeds to step S160 without performing the process in step S150.

  In step S160, a top hat image from which data in the low frequency region is deleted is acquired.

  Specifically, in the spatial frequency determination process, whether the pixel to be processed is in the low frequency region depending on whether or not the sum of pixel data exceeds a predetermined threshold for a predetermined region centered on the pixel to be processed. It is determined whether or not. For example, when the processing target pixel is “1” in the top hat image, 7 × 7 pixel data centered on the processing target pixel is summed, and if the value is 10 or less, it is determined as the low frequency region, and the processing target The pixel value is “0”. If it is determined that the frequency is not low, “1” is maintained. With the above processing, a top hat image from which data has been deleted can be obtained in the low frequency region of FIG.

  FIG. 11 is a diagram illustrating a top hat image obtained by deleting low frequency region data from the top hat image illustrated in FIG. 10. In the top hat image shown in FIG. 11, the white area is reduced as compared with the top hat image shown in FIG. It can be seen that the portion changed from white to black by the opening process is reduced, and smoothing by the opening process is suppressed.

  Returning to FIG. 6, in step S <b> 170, the difference between the original subfield image and the top hat image from which the data of the low frequency region is deleted is taken and converted to the final subfield image.

  In step S180, the final subfield image obtained is supplied to the data power supply driving circuit 70, and the write discharge Pa is performed based on the supplied subfield image, and the processing flow shown in FIG. 6 is terminated.

  FIG. 12 shows the final fifth subfield image. FIG. 12 shows the final subfield image obtained by subtracting the top hat image data obtained by deleting the low frequency region data from the original fifth subfield image data. As shown in FIG. 12, the final subfield image has more black portions than the fifth subfield image before the processing shown in FIG. 8 and has been subjected to the smoothing process. It can be seen that there are more white parts than the fifth subfield image subjected to the opening process, and the smoothing process is suppressed. Note that the final fifth subfield image shown in FIG. 12 is output to the data electrode driving circuit 70.

  FIG. 13 is a diagram illustrating an output image when the low frequency region processing is not performed and when it is performed. FIG. 13A is an output image of an image display device according to a comparative example when the low frequency region processing is not performed, and FIG. 13B is the first embodiment when the low frequency region processing is performed. It is the output image of the image display apparatus which concerns on. 13C is an enlarged view of an output image area A of the image display device according to the comparative example shown in FIG. 13A, and FIG. 13D is shown in FIG. 3 is an enlarged view of a region A of an output image of the image display device according to Embodiment 1. FIG. FIG. 13E is an enlarged view of a region A at the same location of the input image.

  As shown in FIG. 13C, when the low frequency region processing is not performed by the image display device according to the comparative example, the image quality is deteriorated. On the other hand, as shown in FIG. 13D, when the low frequency region processing is performed by the image display apparatus according to the present embodiment, the image quality degradation as shown in FIG. Compared with the input image of FIG. 13E, it can be seen that there is no significant deterioration in image quality.

  FIG. 14 is a table showing the subfield image data subjected to the image display processing by the image display device according to the first embodiment of the present invention and the number of transitions of the data pulse potential of the input subfield image data. As shown in FIG. 14, it can be seen that the number of transitions is reduced to about 60% by performing the processing according to the image forming method according to the first embodiment. Thereby, the frequency | count of switching of light emission and non-light emission of a light emission cell can be reduced, and reduction of electric power can be aimed at.

  Thus, according to the image display apparatus according to the first embodiment, it is possible to reduce power consumption while suppressing deterioration in image quality.

  In the first embodiment, the example in which the smoothing process is the opening process has been described. However, the smoothing process may be a closing process. In the closing process, the process is performed the same number of times in the order of the expansion process and the contraction process. The specific contents of the expansion process and the contraction process are as described above.

  In the first embodiment, an example in which the top hat process is performed after the smoothing process has been described. However, a black hat process may be performed instead of the top hat process. In the black hat process, the original image is subtracted from the image subjected to the closing process.

  As described above, the smoothing process may be a closing process, and the black hat process may be performed after the smoothing process. Subsequent processing can be performed in the same manner as described above. In this case, the top hat processing means 63 in the smoothing suppression filter 62 shown in FIG. 5 can be replaced with the black hat processing means 63.

  In the first embodiment, an example in which the image display method according to the present embodiment is applied to the fifth subfield has been described. However, the fifth subfield can be applied to other subfields, and a plurality of subfields can be applied. It is also possible to apply to this subfield. For example, in order to reduce quality degradation, it is preferable to apply to subfields with low luminance weighting. For example, the image processing method according to this embodiment is applied to at least one of the first to third subfields. May be applied.

  Furthermore, in the first embodiment, an example in which a plasma display device is used as an image display device has been described. However, if the image display device uses a subfield method using a binary subfield image for gradation expression, The present invention can also be applied to other types of display devices.

[Embodiment 2]
FIG. 15 is a diagram illustrating an example of a processing flow of the image display apparatus and the image display method according to the second embodiment of the present invention. In the second embodiment, an example in which the image display device is configured as a plasma display device will be described. The apparatus configuration of the image display apparatus according to the second embodiment is substantially the same as that of the image display apparatus shown in FIG. 5, and thus the same components are denoted by the same reference numerals and the description thereof is omitted. Omitted.

  FIG. 15 shows the flow of processing until the input color image data of (vertical 165 × horizontal 202) pixels is processed and output to the data electrode driving circuit. As shown in FIG. 1, the image display device according to the second embodiment includes a light emitting cell in which one pixel includes red, green, and blue phosphors 23 </ b> R, 23 </ b> G, and 23 </ b> B arranged in the horizontal direction. The operation of the image forming apparatus and the image forming method according to the second embodiment will be described by taking as an example a case where a one-field image of an 8-bit color image is input.

  In FIG. 15, in step S <b> 200, one field image of an 8-bit color image is input to the video data processing circuit 40. Specifically, in the case of a color image, one field image is input to the video data processing circuit 40 for each of the three colors red, green, and blue.

  FIG. 16 is a diagram showing an example of a one-field image of the input color image. Hereinafter, an example in which this input color image is input will be described.

  Returning to FIG. 15, in step S210, the input 8-bit color image signal is converted into a monochrome image signal.

  In steps S220 and S221, color image data and monochrome image data in one field are converted into eight subfield image data from 1 to 8, respectively.

Each subfield image data is composed of binary signals of “1” or “0”. The luminance weight of the first subfield image is 2 ⁰ = 1, the luminance weight of the second subfield image is 2 ¹ = 2, the luminance weight of the third subfield image is 2 ² = 4, and the fourth subfield The luminance weight of the image is 2 ³ = 8, the luminance weight of the fifth subfield image is 2 ⁴ = 16, the luminance weight of the sixth subfield image is 2 ⁵ = 32, and the luminance weight of the seventh subfield image is Let 2 ⁶ = 64 and the luminance weight of the eighth subfield image be 2 ⁷ = 128. In the present embodiment, the fifth subfield image is processed by the image forming method according to the present embodiment.

  In steps S230 and S231, the image data of the fifth subfield image is opened for each of the color image and the monochrome image. The opening process may be performed by the smoothing filter 61. In addition, since the specific content of the opening process has been described in the first embodiment, the content is omitted. By the opening process, the area where the change of the address data is dense is smoothed.

  In steps S240 and S241, a top hat process is performed on the fifth subfield color image and the fifth monochrome subfield image that have been subjected to the opening process. The top hat processing may be performed by the top hat processing means 63 of the smoothing suppression filter 62. By subtracting the color and monochrome subfield image data after the opening process from the original fifth subfield image data in color and monochrome, it is possible to obtain color and monochrome top hat images, respectively.

  In step S250, it is determined whether or not the processing target pixel (target pixel) is “1” for the red, green, and blue top hat images that have been subjected to the top hat processing. When the pixel to be processed is “0” instead of “1”, no processing is performed and the process proceeds to step S290. On the other hand, when the processing target pixel is “1”, the process proceeds to step S260.

  In step S260, the spatial frequency determination process of the original subfield image is performed using the monochrome top hat image data. If it is determined in step S260 that the region is not a low frequency region, the process proceeds to step S280, and the process proceeds to step S290 without performing any processing. On the other hand, if it is determined that the pixel is in the low frequency region, the process proceeds to step S270, where the processing target pixel “1” is excluded from the color top hat signal and is set to “0”.

  For example, specifically, when the processing target pixel in the color top hat image is “1”, 7 × 7 pixel data centered on the pixel at the same address in the monochrome top hat image is summed, and the value is 10 If it is below, it is determined as the low frequency region, and the value of the pixel to be processed is set to “0”. If it is determined that the frequency is not low, “1” is maintained. With the above processing, as shown in step S290, a top hat image from which data is deleted in the low frequency region is obtained.

  FIG. 17 is a diagram showing a color top hat image from which data in the low frequency region is deleted. FIG. 17A is a diagram showing a red signal top hat image from which data in the low frequency region has been deleted, and FIG. 17B shows a green signal top hat image from which data in the low frequency region has been deleted. FIG. 17C is a diagram showing a top-hat image of a green signal from which data in the low frequency region is deleted. As described above, the image data of the low frequency region can be deleted using the image data of the top hat image of the common monochrome signal. As a result, the amount of calculation can be reduced as compared with the case where the spatial frequency determination process and the suppression process for deleting data in the low frequency region are individually performed on each of the red, green, and blue subfield images.

  Returning to FIG. 15, in step S300, the top hat image of each color is converted into a subfield image of each color, and a final fifth subfield image is obtained. The final subfield image is obtained by subtracting the top hat image data obtained by deleting the low frequency region data shown in FIG. 17 from the original fifth subfield image data. In the final sub-field image, the top hat processing is suppressed in the low frequency region where the luminance change is gentle, so that the image quality deterioration can be suppressed.

  In step 310, the obtained red, green, and blue subfield images are output to the data electrode driving circuit 70, respectively.

  FIG. 18 is a table showing the number of transitions of the data field potential of subfield image data subjected to image display processing by the image display apparatus according to the second embodiment of the present invention and input subfield image data. As shown in FIG. 18, the number of transitions of the data pulse Pd is reduced to about 70% by performing the processing according to the image display method according to the second embodiment. As described above, according to the image display apparatus and the image display method according to the second embodiment, it is understood that the effect of reducing the power consumption can be obtained by reducing the number of transitions of light emission / non-light emission of the light emitting cells.

  As described above, according to the image display apparatus and the image display method according to the second embodiment, it is possible to reduce power consumption while suppressing deterioration in image quality of a color image. In the smoothing suppression process, the spatial frequency determination process and the suppression process are performed in common for the three subfields of red, green, and blue using a monochrome image, so that the amount of calculation can be reduced.

  Note that the present embodiment can be applied to subfields other than the fifth subfield, for example, at least one of the first to third subfields, the opening process is replaced with a closing process, and the top hat process is replaced with a back hat process. The point which can be applied to an image display device using a subfield method other than the plasma display device is the same as that of the first embodiment.

  In the image display device and the image display method according to the second embodiment, the example of performing the spatial frequency determination process and the suppression process using a monochrome image has been described, but three subfields of red, green, and blue are used. It is also possible to apply the processing described in the image display method according to the first embodiment individually to an image. Although the amount of calculation increases, highly accurate smoothing suppression processing can be performed.

  According to the present invention, in a display device that displays halftones by the subfield method, smoothing of subfield image data performed for the purpose of reducing power loss caused by potential transition of data pulses is smoothed in a region where the luminance change is gentle. By performing the spatial filter process that suppresses the smoothing, the smoothing process can be performed even on the subfield image having a large luminance weight that has a large influence on the image quality, and a greater power reduction effect can be obtained.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

DESCRIPTION OF SYMBOLS 12 Scan electrode 13 Sustain electrode 22 Data electrode 30 Plasma display panel 40 Image | video data processing circuit 50 Control signal generation circuit 60 Address data processing circuit 61 Smoothing filter 62 Smoothing suppression filter 63 Top hat processing means 64 Spatial frequency determination means 65 Suppression means 70 Data electrode drive circuit 80 Scan electrode drive circuit 90 Sustain electrode drive circuit

Claims (10)

An image display device that divides a field image into a plurality of binary subfield images weighted to luminance and performs gradation display by temporally superimposing the subfield images,
An address data processing circuit for generating address data corresponding to the subfield image;
The address data processing circuit comprises: smoothing means for smoothing a region where changes in address data are dense in at least one of the subfield images;
An image display apparatus comprising: a smoothing suppression unit that suppresses the smoothing in a region where the luminance change of the at least one subfield image is moderate.   The image display apparatus according to claim 1, wherein the smoothing unit performs an opening process or a closing process on the subfield image.   The smoothing suppression unit obtains a top hat image or a black hat image by taking a difference between the image data subjected to the opening process or the closing process and the image data of the subfield image before the process, The image display device according to claim 2, wherein the image data of the hat image or the black hat image is a processing target.   The image display according to claim 3, wherein the smoothing suppression unit performs a spatial frequency determination process for determining whether a processing target pixel of the image data of the top hat image or the black hat image is in a low frequency region. apparatus.   In the spatial frequency determination process, a threshold is provided for the ratio of the total number of pixels to which writing is not performed with respect to the total number of pixels in a predetermined peripheral setting area of the processing target pixel, and an area where the luminance change of the image data is moderate is determined. The image display device according to claim 4, which is a process.   The image display device according to claim 1, wherein the smoothing suppression unit performs a process of returning the pixels in the region where the luminance change is gentle to a state in which the smoothing is not performed.   The image display according to any one of claims 2 to 6, wherein the smoothing unit performs the opening process or the closing process on a predetermined number of pixels including the front and back on the same data electrode as the pixel to be processed. apparatus. The field image is a color field image including field images of three colors of red, green, and blue,
The image display device according to claim 1, wherein a subfield image of each color is a processing target.   The image display device according to claim 8, wherein the smoothing suppression unit converts the color field image into a monochrome image signal and determines the region where the luminance change is gradual using the monochrome image signal. An image display method for performing gradation display by dividing a field image into a plurality of binary subfield images weighted to luminance and superimposing the subfield images temporally,
Generating address data corresponding to the subfield image;
Smoothing a region where changes in address data are dense in at least one of the subfield images;
Performing a smoothing suppression process for suppressing the smoothing in a region where the luminance change of the at least one subfield image is moderate.