JP3591217B2 - Multi-tone image display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, in a display device in which one field of an image is divided into a plurality of sub-field images and displayed to perform multi-gradation display, it is possible to improve gradation disturbance of halftone display that occurs at the time of displaying a moving image. And a multi-tone image display device for displaying images.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when performing gradation display using a display device that divides and displays one field of an image into a plurality of subfield images and performs multi-gradation display, for example, a plasma display device, a so-called moving image display is used. It is known that pseudo-contour-like gradation disturbance occurs.
[0003]
The generation of the pseudo contour at the time of displaying the moving image will be described with reference to FIG. FIG. 11 shows a state in which an image having a pattern in which two levels of level 15 and level 16 are adjacent (an example is shown in FIG. 12) is displayed and when the adjacent pattern follows a pattern which has been translated. Is shown.
[0004]
In a display device that divides one field of an input image into a plurality of subfields and performs gradation display, when a still image is displayed, the average luminance of one field of the observed image is between AA ′ in FIG. It is expressed by integration of light emission, and a correct gradation display is performed.
[0005]
On the other hand, when a moving image is displayed, the integration of light emission between B-B 'or C-C' in FIG. 11 is observed on the retina according to the direction of movement of the line of sight. Between B-B ', the combined value of each bit is almost 0, and the sum of each bit between C-C' is almost 31. As described above, when observing a portion where two levels 15 and 16 are adjacent to each other, the luminance level observed at the level change portion is significantly disturbed by the motion of the image as shown in FIG.
[0006]
Note that, in FIG. 11, light emission is continuously performed with a predetermined width for each subfield. However, in an actual plasma display, each subfield has the number of times corresponding to each luminance weight. Although it is composed of a set of pulsed light emission, the gradation disturbance at the time of displaying a moving image is essentially the same.
[0007]
As described above, since an attempt is made to express the halftone by integrating the luminance of each subfield in the time direction, if the line of sight moves in a moving image, the image at the position different from the original pixel position with time elapses. Since the weight of each bit is integrated, the halftone display is greatly disturbed. Since this halftone disturbance is recognized so that a false contour appears in the image, it is hereinafter referred to as a moving image pseudo contour.
[0008]
As an attempt to reduce the pseudo-contour of a moving image, in a conventional image display device, the luminance weight of a subfield corresponding to a plurality of upper bits is divided, and the luminance is divided and arranged so that halftone display in a moving image display is performed. Attempts have been made to reduce turbulence.
[0009]
FIG. 13 shows a subfield configuration in the moving image pseudo contour reducing method according to the conventional method, in which 8-bit gradation, that is, 256 gradations is displayed by using 10 subfields. The luminance weighting of each subfield is 48, 48, 1, 2, 4, 8, 16, 32, 48, and 48, respectively. The luminance weights of the upper two bits 64 and 128 of the original input image signal are divided into four and distributed at both ends of the subfield. The weight of the most significant bit is reduced to minimize the occurrence of halftone disturbance. In addition, by distributing large subfields at the beginning and end of the subfield in a distributed manner, blurring occurs in the image observed when displaying a moving image, and it is intended to make the pseudo contour of the moving image inconspicuous Is what you do.
[0010]
[Problems to be solved by the invention]
As shown in FIG. 13, in the conventional image display device, the subfields having the highest luminance weight are dispersedly arranged in the first half and the second half of one field. FIG. 13 shows an example of on / off control of each subfield with respect to the input image signal level.
[0011]
For example, as the signal level of the input image signal increases from 143 to 144, the number of “luminance weighting = 48” subfields that are turned on decreases from two to three. At this time, although the level of the input image signal is slightly increased by 1, the subfield with the largest luminance weight is turned on at a position temporally separated.
[0012]
For this reason, when the same phenomenon as in FIG. 11 is observed, that is, when a moving image is observed while the sight line follows, as shown in FIG. 13A and FIG. Disturbance occurred, and the suppression of false contours of the moving image was insufficient. The four subfields of “luminance weight = 48” spaced apart at both ends form a total of 192 luminance weights, and occupy most of the total luminance weights. Therefore, when an image is displayed and the line of sight follows, the observed image is a combination of temporally separated image components, and as a result, the moving image portion has image blur. For this reason, there is also a problem that image quality is deteriorated such that moving fine characters are duplicated and cannot be read.
[0013]
In order to solve the above-described problem, a multi-tone image display device according to the present invention divides one field of an input signal into a plurality of M subfields having a predetermined luminance weight, and turns on each of the subfields. An image display apparatus that performs multi-tone display by control or off control, wherein a plurality of L (L ≧ 3) in which the luminance weight of each of the plurality of M subfields is equal to or greater than a predetermined value ) Is a first subfield group, the remaining ML subfields are a second subfield group, and L-1 subfields among the subfields belonging to the first subfield group Fields are arranged in a continuous order, and one of the subfields belonging to the first subfield group belongs to the second subfield group. That is sandwiched between the plurality of sub-fields are arranged, a second sub-field group to sandwich the sub-fields belonging to the first subfield groupIs beforeBefore and after the position to insertThe sum of the respective luminance weights atTo be closestPlace subfieldIt is characterized by having done.
[0014]
Further, in the multi-tone image display device according to the present invention, the sum of the luminance weights of the second subfield group sandwiching the subfields belonging to the first subfield group may be before and after the position where the sandwiching is performed.ClosestIt is characterized by having become.
[0015]
Further, in the multi-tone image display device according to the present invention, the luminance weight of each sub-field belonging to the first sub-field group monotonically increases.AdditionOrder, Or an order having parts with the same luminance weight and parts with monotonic increaseIt is characterized by being arranged at.Alternatively, in the multi-tone image display device according to the present invention, the order in which the luminance weights of the sub-fields belonging to the first sub-field group decrease monotonically, or a part having the same luminance weight and a part decreasing monotonously Are arranged in the order having
[0017]
Also, in the multi-tone image display device according to the present invention, when the on-control of each of the first sub-fields displays the signal level of the input signal in ascending order, When a subfield having a large luminance is first selected and turned on, it is possible to suppress the on control of a subfield adjacent to the subfield having the highest luminance weight among the subfields that are controlled to be on, thereby enabling predetermined luminance display. The subfield is controlled to be selected and displayed.
[0018]
According to the present invention, an image display in which one field of an input signal is divided into a plurality of M subfields having a predetermined luminance weight, and a multi-gradation display is performed by ON control or OFF control of each of the subfields In the apparatus, among the plurality of M subfields, a plurality of L subfields in which the luminance weight of each subfield is equal to or more than a predetermined value is defined as a first subfield group, and the remaining ML subfields are used. The subfields are defined as a second subfield group, and a maximum of L-1 subfields among the subfields belonging to the first subfield group are arranged in a continuous order. When the input signal level continuously changes, the light emission pattern of each subfield fluctuates extremely. : It is inhibited, it is possible to suppress the so-called dynamic false contour over a wide range of input signal levels.
[0019]
In addition, since the subfields with large luminance weights are concentrated, when the moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and the moving fine characters are doubled. , The image quality can be prevented from being degraded.
[0020]
Further, according to the present invention, at least one of the subfields belonging to the first subfield group is arranged so as to be sandwiched between a plurality of subfields belonging to the second subfield group. In particular, in a low-luminance or middle-luminance portion where accurate gradation expression is required, it is possible to reduce a so-called pseudo contour of a moving image.
[0021]
Further, according to the present invention, since the luminance weights of the subfields belonging to the first subfield group are arranged in an order of monotonically increasing or monotonically decreasing, the luminance weights are relatively low at low luminance. The predetermined luminance can be expressed using only the small and close subfields. In particular, it is possible to suppress the occurrence of the moving image pseudo contour at low luminance where the moving image pseudo contour is conspicuous.
[0022]
According to the present invention, the luminance weight of each subfield belonging to the first subfield group is obtained by increasing the sum of the luminance weights of each subfield belonging to the second subfield group by one luminance weight. Therefore, the details of the level of the input signal are expressed by on-control or off-control of each subfield belonging to the second subfield group. It can be expressed by on-control or off-control of each subfield belonging to the first subfield group, and detailed grayscale display can be performed without loss over the previous range of the input signal.
[0023]
Further, according to the present invention, when the on-control of the first sub-field displays the signal levels of the input signals in ascending order, the sub-field having the largest luminance weight among the on-controlled sub-fields is displayed. When selected and turned on for the first time, a sub-field in which predetermined brightness can be displayed by suppressing the on-control of a sub-field adjacent to the sub-field having the largest luminance weight among the sub-fields being on-controlled is selected. At the signal level change point, which is said to be relatively easy to generate a moving image false contour, a subfield having the largest luminance weight is selected first among the subfields that are on-controlled. When turned on, the subfield adjacent to the subfield having the largest luminance weight among the subfields that are controlled to be turned on is By avoiding the ON control of the subfield as much as possible, instead of selecting a distant subfield and displaying the predetermined luminance, the pseudo contour of the moving image is equivalently partially canceled, and a good moving image display can be performed. it can.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
The multi-tone image display device according to the present invention (claims 1, 6 to 9) divides one field of an input signal into a plurality of M subfields having a predetermined luminance weight, and In an image display device that performs multi-tone display by on-control or off-control, among the plurality of M sub-fields, a plurality of L sub-fields, each of which has a luminance weight equal to or more than a predetermined value, is assigned to a 1 subfield group, the remaining ML subfields as a second subfield group, and a maximum of L-1 subfields of the subfields belonging to the first subfield group are arranged in a continuous order. And at least one of the subfields belonging to the first subfield group belongs to the second subfield group. It is a multi-tone image display apparatus being characterized in that disposed by sandwiching a plurality of sub-fields.
[0025]
For this reason, since the approximate part of the luminance information of the image is represented by the emission of the subfields arranged continuously, when the level of the input signal continuously changes, the emission pattern of each subfield is originally set. Due to the concentration, extreme fluctuation of the relative light emission position is suppressed, and so-called moving image false contour can be suppressed over a wide range of the input signal level. In addition, since the subfields with large luminance weights are concentrated, when the moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and the moving fine characters are doubled. , The image quality can be prevented from being degraded.
[0026]
Also, in the multi-tone image display device according to the present invention (claims 2 and 6 to 9), the sum of the luminance weights of the second subfield group that sandwiches the subfields belonging to the first subfield group may be equal to the sandwiching. , The so-called moving image false contour can be reduced particularly in a low luminance or middle luminance portion where accurate gradation is required to be expressed.
[0027]
In the multi-tone image display device according to the present invention (claims 3 and 6 to 9), the luminance weights of the sub-fields belonging to the first sub-field group are arranged in a monotonically increasing or monotonically decreasing order. A multi-tone image display device characterized in that: For this reason, at low luminance, a predetermined luminance can be expressed using only adjacent sub-fields having relatively small luminance weights. It can be suppressed and displayed.
[0028]
Also, in the multi-tone image display device according to the present invention (claims 4 and 6 to 9), each of the sub-fields belonging to the first sub-field group may have a luminance weight belonging to the second sub-field group. A multi-tone image display device characterized in that the sum of the luminance weights of the subfields is an integer multiple of the luminance weight increased by 1, and the level of the input signal belongs to the second subfield group. Each of the subfields is controlled by on or off control, and the level of the input signal can be roughly expressed by on or off control of each of the subfields belonging to the first subfield group. ON control or OFF control can be easily performed.
[0029]
Further, in the multi-tone image display device according to the present invention (claim 5), the on-control of the first sub-field is controlled when the signal level of the input signal is displayed in ascending order. When the subfield having the highest luminance weight is first selected and turned on, the on-control of the subfield adjacent to the subfield having the highest luminance weight among the on-controlled subfields is suppressed to a predetermined value. A multi-tone image display device characterized in that control is performed to select and display a subfield that enables luminance display, and at a signal level change point where it is relatively easy to generate a moving image false contour, As described above, when the subfield having the highest luminance weight among the subfields that are controlled to be turned on is first selected and turned on, Since the on-control of the sub-field adjacent to the sub-field having the largest luminance weight among the controlled sub-fields is avoided as much as possible, instead, a distant sub-field is selected and a predetermined luminance is displayed. Partially canceled, good moving image display can be performed.
[0030]
(Embodiment 1)
Hereinafter, embodiments of the present invention (claims 1 and 2) will be described with reference to the drawings. In FIG. 2, reference numeral 1 denotes an input signal, 2 denotes an A / D converter for converting the input signal into an 8-bit digital signal, and 3 denotes an image signal represented by an 8-bit digital signal composed of 10 subfields. This is a sub-field conversion circuit for rearranging the signals into the sub-fields. 4 is a plasma display. The plasma display 4 is a display device that performs binary light emission of ON or OFF, and the brightness is expressed by the sum of the light emission of 10 subfields each having a predetermined number of light emission times as the brightness weight, and the halftone display is performed. Is made possible.
[0031]
In the multi-tone image display device configured as described above, the order of each subfield and each luminance weight are represented by the relationship shown in FIG. As shown in FIG. 1, in the multi-tone image display device of the present embodiment, one field of an input signal is divided into ten sub-fields, and six sub-fields each having a luminance weight of 16 or more. A first subfield group consisting of subfields (luminance weights are 16, 16, 32, 48, 48, and 80, respectively), and four subfields (luminance weights are 8 or less) Each of the subfields belonging to the first subfield group is divided into a second subfield group consisting of 1, 2, 4, and 8), and one of the subfields belonging to the first subfield group (the subfield with the luminance weight = 16) is set to It is arranged sandwiched between subfield groups. That is, when the arrangement of the ten subfields is represented using the luminance weight,
1,2,4,16,8,16,32,48,48,80
The arrangement is such that
[0032]
The subfield conversion circuit 3 shown in FIG. 2 converts an input signal into a digital video signal obtained by A / D conversion and a subfield control signal, and performs control as shown in FIG. In FIG. 3, the subfield marked "1" is turned "on", and the subfield marked "0" is turned off for the field period.
[0033]
Note that the lower 4 bits of the digital video signal are used as they are for on / off control of the second subfield group.
[0034]
In the multi-tone image display device configured as described above, first, when the value of the digital video signal changes from 15 to 16, as shown below, the arrangement of the sub-fields to be turned on is averaged. Therefore, the false contour of the moving image at the level change portion is suppressed. Note that this portion has relatively low luminance, and a slight change in level is likely to cause a large change in hue, and it is extremely important to suppress the generation of moving image false contours.
[0035]
Subfield luminance weight: 1, 2, 4, 16, 8, 16, 32, 48, 48, 80
When level = 15: 1 1 1 1 1 1 1 0 0 0 0 0 0
When level = 16: 0 0 0 1 0 0 0 0 0 0 0
Also, as can be seen from the portion surrounded by the thick frame in FIG. 3, when the signal levels of the digital video signals are displayed in ascending order, the subfield having the largest luminance weight among the subfields that are on-controlled is selected first. When the sub-field is turned on, the on-control of the sub-field adjacent to the sub-field having the largest luminance weight among the sub-fields whose on-state is controlled is suppressed as much as possible, and the separated sub-fields are combined so as to have a predetermined luminance weight. ing. For this reason, at a signal level at which a so-called moving image pseudo contour is likely to occur, a pseudo contour is compared with a sub field adjacent to the sub field having the largest luminance weight among the sub fields that are turned on and emits light. Can be suppressed.
[0036]
FIG. 4 shows a relative value of the moving image pseudo contour amount when a conventional eight subfields, that is, a subfield configuration in which the luminance weight is 1, 2, 4, 8, 16, 32, 64, or 128 is used. On the other hand, FIG. 5 shows a relative value of the moving image pseudo contour amount when the subfield configuration according to the embodiment of the present invention is used. Note that these figures are obtained by simulation when the movement of pixels per field is 12 pixels. As can be seen from FIGS. 4 and 5, by using 10 sub-fields and using the sub-field conversion configured in the above-described configuration and order, the moving image pseudo-comparison is performed in comparison with the conventional 8-sub-field method. The generation of the contour can be greatly suppressed.
[0037]
(Embodiment 2)
Hereinafter, an embodiment of the present invention (claim 8) will be described with reference to the drawings with respect to portions different from the first embodiment of the present invention. In FIG. 6, reference numeral 1 denotes an input signal, 2 denotes an A / D converter for converting the input signal into an 8-bit digital signal, and 31 denotes an image signal represented by an 8-bit digital signal composed of 11 subfields. This is a sub-field conversion circuit for rearranging the signals into the sub-fields. In the multi-tone image display device of the present embodiment, an 8-bit digital video signal is converted into a signal composed of 11 subfields and supplied to the plasma display 4. The plasma display 4 is a display device that performs binary light emission of ON or OFF, and the brightness is expressed by the sum of the light emission of 11 subfields each having a predetermined number of light emission times as the brightness weight, and the halftone display is performed. Is made possible.
[0038]
In the multi-tone image display device configured as described above, the order of each subfield and each luminance weight are represented by the relationship shown in FIG. As shown in FIG. 7, in the multi-tone image display device of the present embodiment, one field of the input signal is divided into 11 sub-fields, and each sub-field has seven luminance weights of 16 or more. A first subfield group consisting of subfields (luminance weights are 16, 16, 32, 32, 48, 48, and 48, respectively) and four subfields (luminance weights of each subfield being 8 or less) The weights are divided into a second subfield group consisting of 1, 2, 4, 8), and one of the subfields belonging to the first subfield group (subfield with luminance weight = 16) is assigned to the second subfield group. It is arranged so as to be sandwiched between two subfield groups.
[0039]
That is, when the arrangement of the eleven subfields is represented using the luminance weight,
1,2,4,16,8,16,32,32,48,48,48
The arrangement is such that
[0040]
The subfield conversion circuit 31 shown in FIG. 6 converts an input signal into a digital video signal obtained by A / D conversion and a subfield control signal, and performs control as shown in FIG. In FIG. 8, the subfield described as “1” is turned “on”, and the subfield described as “0” is turned off during the field period.
[0041]
Note that the lower 4 bits of the digital video signal are used as they are for on / off control of the second subfield group.
[0042]
In the multi-tone image display device configured as described above, first, when the value of the digital video signal changes from 15 to 16, the subfield arrangement as described above is used. The suppression of the moving image pseudo-contour in the part is the same as in the first embodiment, and it is very effective to prevent a slight change in level caused by the moving image pseudo-contour from becoming a large change in hue.
[0043]
As can be seen from the portion surrounded by the thick frame in FIG. 8, when the signal levels of the digital video signals are displayed in ascending order, the subfield having the largest luminance weight among the subfields that are on-controlled is selected first. When the sub-field is turned on, the on-control of the sub-field adjacent to the sub-field having the largest luminance weight among the sub-fields whose on-state is controlled is suppressed as much as possible, and the separated sub-fields are combined so as to have a predetermined luminance weight. ing. Therefore, at a signal level at which a so-called moving image false contour is likely to occur, the false contour can be canceled equivalently.
[0044]
As described above, by using 11 subfields and using the configuration and the subfield conversion as described above, it is possible to significantly suppress the generation of a moving image false contour as compared with the related art.
[0045]
(Embodiment 3)
Hereinafter, an embodiment of the present invention (claim 9) will be described with reference to the drawings with respect to portions different from the first and second embodiments.
[0046]
In FIG. 9, reference numeral 1 denotes an input signal, 2 denotes an A / D converter for converting the input signal into an 8-bit digital signal, and 32 denotes an image signal represented by an 8-bit digital signal composed of 12 subfields. This is a sub-field conversion circuit for rearranging the signals into the sub-fields. In the multi-tone image display device of the present embodiment, an 8-bit digital video signal is converted into a signal composed of 12 subfields and supplied to the plasma display 4. The plasma display 4 is a display device that performs binary light emission of ON or OFF. The luminance is expressed by the sum of the light emission of 12 subfields each having a predetermined number of light emission times as the luminance weight, and the halftone display is performed. Is made possible.
[0047]
In the multi-tone image display device according to the present embodiment, an 8-bit digital video signal is divided into 12 subfields and supplied to the plasma display 4. The plasma display 4 is a display device that performs binary light emission of ON or OFF. The luminance is expressed by the sum of the light emission of 12 subfields each having a predetermined number of light emission times as the luminance weight, and the halftone display is performed. Is made possible.
[0048]
In the multi-tone image display device configured as described above, the order of each subfield and each luminance weight are represented by the relationship shown in FIG. As shown in FIG. 10, in the multi-tone image display device of the present embodiment, one field of an input signal is divided into 12 sub-fields, and each sub-field has eight luminance weights of 16 or more. A first subfield group consisting of subfields (luminance weights are 16, 16, 32, 32, 32, 48, and 48, respectively) and four subfields (luminance weights of each subfield being 8 or less) The weights are divided into a second subfield group consisting of 1, 2, 4, and 8), and one of the subfields belonging to the first subfield group (the subfield of luminance weight = 16) is assigned to the second subfield group. It is arranged so as to be sandwiched between two subfield groups.
[0049]
That is, when the arrangement of the eleven subfields is represented using the luminance weight,
1: 2: 4: 16: 8: 16: 16: 32: 32: 32: 48: 48
The arrangement is such that
[0050]
Also in the present embodiment, when the signal levels of the digital video signals are displayed in ascending order, when the subfield having the highest luminance weight is selected first and turned on among the subfields that are controlled to be turned on, this ON control is performed. The sub-field adjacent to the sub-field having the largest luminance weight among the sub-fields is suppressed as much as possible, and by combining distant sub-fields to have a predetermined luminance weight, a so-called moving image pseudo contour is obtained. At a signal level that is likely to occur, the pseudo contour can be canceled equivalently.
[0051]
As described above, by using 12 subfields and using the configuration and the subfield conversion as described above, it is possible to greatly suppress the generation of a moving image false contour as compared with the related art.
[0052]
When one field of the input signal is divided into nine sub-fields and multi-gradation display is performed by on-control or off-control of each of the sub-fields, the luminance weight of the nine sub-fields is A subfield group having a ratio of 16: 32: 48: 64: 80 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: 8. Is a second sub-field group, and the nine sub-field groups have a luminance weight ratio of 1: 2: 4: 16: 8: 32: 48: 64: 80 or vice versa. It may be arranged as follows.
[0053]
【The invention's effect】
As described above, according to the multi-tone image display device of the present invention, the following effects can be obtained.
[0054]
A multi-tone image display device according to the present invention (claim 1) divides one field of an input signal into M sub-fields, and L sub-fields in which the luminance weight of each sub-field is a predetermined value or more. A first subfield group consisting of a first subfield and a second subfield group consisting of ML subfields in which the luminance weight of each subfield is equal to or less than a predetermined value. Since at least one of the sub-fields belonging to the group is interposed between the second sub-field group, particularly in a low luminance or middle luminance part where accurate gradation expression is required, It is possible to reduce so-called moving image false contours.
[0055]
In addition, since the subfields with large luminance weights are concentrated, when the moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and the moving fine characters are doubled. , The image quality can be prevented from being degraded.
[0056]
Further, in the multi-tone image display device according to the present invention (claim 2), the sum of the luminance weights of the second sub-field group sandwiching the sub-fields belonging to the first sub-field group is determined by the position at which the sandwiching is performed. So that the so-called moving image false contour can be reduced particularly in a low-luminance or middle-luminance portion where accurate gradation expression is required.
[0057]
Further, in the multi-tone image display device according to the present invention (claim 3), the luminance weights of the respective sub-fields belonging to the first sub-field group are arranged in the order of monotonically increasing or monotonically decreasing. Therefore, at low luminance, predetermined luminance can be expressed using only adjacent subfields having relatively small luminance weights, and in particular, the generation of moving image pseudo-contours at low luminance where moving image pseudo-contours are conspicuous is suppressed. Can be displayed.
[0058]
Further, in the multi-tone image display device according to the present invention (claim 4), the luminance weight of each sub-field belonging to the first sub-field group may be different from that of each sub-field belonging to the second sub-field group. Since the total of the luminance weights is an integral multiple of the luminance weight incremented by 1, the on / off control of each subfield belonging to the second subfield group covers the details of the level of the input signal, The outline of the level of the input signal can be expressed by on / off control of each subfield belonging to the first subfield group, and on / off control of each subfield can be easily performed.
[0059]
Further, in the multi-tone image display device according to the present invention (claim 5), when the subfield having the highest luminance weight is first selected and turned on among the subfields that are controlled to be on, the on-control is performed. Of the subfields adjacent to the subfield with the highest luminance weight among the subfields that have the highest luminance, and instead select a subfield that is farther away and display the specified luminance. As a result, a favorable moving image can be displayed.
[0060]
Further, the multi-tone image display device according to the present invention (claims 6 to 9) uses 9 to 12 subfields, and uses the above-described configuration and subfield conversion to obtain the conventional 8 subfields. As compared with the driving method using, the generation of the false contour of the moving image can be largely suppressed.
[0061]
It should be noted that the effects of the present invention are not limited to the specific cases described in the embodiments described above, and various modifications such as increasing the number of subfields and reversing the order of subfields are possible. Needless to say. Further, the encoding method for determining the correspondence between the digital video signal and the signal subjected to the subfield conversion is not limited to the method illustrated in the present specification, and various modifications within the scope of the claims of the present invention are also possible. Of course it is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing subfield numbers and luminance weighting of each subfield in Embodiment 1 of the present invention.
FIG. 2 is a configuration diagram of a multi-tone image display device according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a method of on / off control of a subfield according to the first embodiment of the present invention;
FIG. 4 is a diagram showing a generation amount of a moving image false contour according to a conventional method using eight subfields.
FIG. 5 is a diagram showing a generation amount of a moving image pseudo contour according to the first embodiment of the present invention;
FIG. 6 is a configuration diagram of a multi-tone image display device according to a second embodiment of the present invention.
FIG. 7 is a diagram showing subfield numbers and luminance weighting of each subfield according to the second embodiment of the present invention;
FIG. 8 is a diagram showing a method for on / off control of a subfield according to a second embodiment of the present invention.
FIG. 9 is a configuration diagram of a multi-tone image display device according to a third embodiment of the present invention.
FIG. 10 is a diagram showing subfield numbers and luminance weighting of each subfield according to Embodiment 3 of the present invention.
FIG. 11 is a diagram showing a cause of generation of a moving image false contour;
FIG. 12 shows an example of an image having two adjacent levels.
FIG. 13 is a diagram showing a moving image pseudo contour in a conventional example using 10 subfields.
[Explanation of symbols]
1 Input image signal
2 A / D converter
3 Subfield conversion circuit
4 Plasma display
31 Subfield conversion circuit
32 subfield conversion circuit

Claims (8)

An image display device which divides one field of an input signal into a plurality of M subfields having a predetermined luminance weight, and performs multi-gradation display by ON control or OFF control of each subfield,
Among the plurality of M subfields, a plurality of L (L ≧ 3) subfields in which the luminance weight of each subfield is equal to or more than a predetermined value is defined as a first subfield group, and the remaining M-L Subfields as a second subfield group, and L-1 subfields among the subfields belonging to the first subfield group are arranged in a continuous order;
One subfield among the subfields belonging to the first subfield group is interposed and arranged between a plurality of subfields belonging to the second subfield group;
Said first sub-field second subfield group to sandwich the sub-fields belonging to the group, the sum of each subfield weights before and after the position for pre-Symbol entrapment placed the subfields to be closest to each other Characteristic multi-tone image display device. The sub-fields belonging to the first sub-field group are arranged in an order in which luminance weights are monotonically increasing, or are arranged in an order having a portion having the same luminance weight and a monotonically increasing portion. Item 2. The multi-tone image display device according to Item 1. 9. The method according to claim 8, wherein the luminance weights of the subfields belonging to the first subfield group are arranged in a monotonically decreasing order, or are arranged in an order having the same luminance weighting portion and a monotonically decreasing portion. Item 2. The multi-tone image display device according to Item 1. The luminance weight of each of the subfields belonging to the first subfield group is an integer multiple of the sum of the luminance weights of each of the subfields belonging to the second subfield group increased by one. The multi-tone image display device according to claim 1, wherein: An image display device that divides one field of an input signal into nine subfields and performs multi-gradation display by ON control or OFF control of each of the subfields, wherein: A subfield group having a weight ratio of 16: 32: 48: 64: 80 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: 8. The field group is a second subfield group, and the nine subfield groups are in the order of a luminance weight ratio of 1: 2: 4: 16: 8: 32: 48: 64: 80 or vice versa. The multi-tone image display device according to any one of claims 1 to 4, wherein the multi-tone image display device is arranged so that: An image display device which divides one field of an input signal into ten sub-fields and performs multi-gradation display by ON control or OFF control of each of the sub-fields, wherein: A subfield group having a weight ratio of 16: 16: 32: 48: 48: 80 is a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: 8. A certain subfield group is defined as a second subfield group, and the ten subfield groups are arranged in the order of the luminance weight ratio of 1: 2: 4: 16: 8: 16: 32: 48: 48: 80, or 5. The multi-tone image display device according to claim 1, wherein the multi-gradation image display device is arranged so that the order is reversed. An image display device which divides one field of an input signal into 11 subfields and performs multi-gradation display by ON control or OFF control of each of the subfields, wherein: A subfield group having a weight ratio of 16: 16: 32: 32: 48: 48: 48 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: The subfield group of 8 is a second subfield group, and the 11 subfield groups have a luminance weight ratio of 1: 2: 4: 16: 8: 16: 32: 32: 48: 48: 48. The multi-tone image display device according to any one of claims 1 to 4, wherein the multi-tone image display device is arranged so as to have the following order or the reverse order. An image display device which divides one field of an input signal into twelve sub-fields and performs multi-tone display by ON control or OFF control of each of the sub-fields, wherein: A subfield group having a weight ratio of 16: 16: 16: 32: 32: 32: 48: 48 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: A subfield group of 4: 8 is defined as a second subfield group, and the 12 subfield groups have a luminance weight ratio of 1: 2: 4: 16: 8: 16: 16: 32: 32: 32. The multi-tone image display device according to any one of claims 1 to 4, wherein the multi-tone image display device is arranged so as to be in the order of :: 32: 48: 48: or the reverse order.

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