Abstract: A plasma display panel and a driving method thereof. In the plasma display panel, Y electrodes are divided into a plurality of groups according to a scanning order and a final reset voltage is established to be different for each group. The plasma display panel includes a panel including a plurality of first electrodes and second electrodes, a plurality of selection circuits that are respectively coupled to the plurality of the first electrodes, and a driving circuit coupled to the second terminals of the selection circuits. The driving circuit includes a transistor which allows the voltage at the first electrodes to be reduced in a ramp style in a reset period.

Abstract: This invention relates to a driving apparatus of a plasma display panel that is capable of being operated stable, regardless of temperature. A driving apparatus of a plasma display panel according to the present invention includes a panel having a scanning electrode for receiving a scanning pulse in an address period and an address electrode for receiving a date pulse synchronized with the scanning pulse in the address period; and a pulse width controller for changing the width of the scanning pulse when the panel is driven at a low temperature.

Abstract: A driving method for a plasma display panel to improve brightness when the load is low is provided. The driving method of the plasma display panel includes allocating a first number of sustain pulses for driving the plasma display panel when a load of the plasma display panel exceeds a reference load. The first number of sustain pulses is allocated as a function of a power consumption of the plasma display panel. The method further includes allocating a second number of sustain pulses for driving the plasma display panel when the load is less than the reference load. The second number of sustain pulses is allocated to improve brightness.

Abstract: A PDP apparatus, the peak luminance of which has been improved with little modification of the existing circuit structure, has been disclosed, in which a thinning process that shortens an address period by hiding part of display lines in a fixed subfield of a low luminance is performed, the saved time is increased by an amount corresponding to that from which the luminance weight (the number of sustain discharge pulses, that is, the length of the sustain discharge period) of the thinned subfield of a low luminance is subtracted, and the remaining time is allocated at the ratio of the luminance weights on completion of the first step in each subfield.

Abstract: Systems and methods of controlling client display modes are disclosed. In one embodiment, an electronic device includes an array of interferometric modulators, and an array driver for the array of interferometric modulators. The array driver is configured to receive video data which at least a portion of is in an interlaced format, to identify a portion of the video data as interlaced format, and to render the identified video data in an interlaced format on the array of interferometric modulators. In another embodiment, a method of displaying information on a bi-stable display includes receiving video data at a device having an interlaced mode of displaying data and a non-interlaced mode of displaying data, identifying at least a portion of the video data as interlaced format, and displaying the interlaced video data on the bi-stable display. In some embodiments the bi-stable display can be an array of interferometric modulators.

Abstract: A method of driving a plasma display panel (PDP) capable of improving gray scale display comprises the steps of applying pulses having a first voltage to first electrodes and second electrodes during a sustain period of at least one subfield and reducing a voltage of the first electrodes to a voltage of no more than one-half of the first voltage while maintaining a voltage of the second electrode at a second voltage.

Abstract: A method of expressing gray scales of a plasma panel display using the sum of weights assigned to subfields, including extracting a first gray scale arrangement including gray scale n using (k?1) subfields to gray scale m using k subfields from a second gray scale arrangement including gray scale 1 to gray scale m using k subfields between the 1st and the jth subfields when the number of subfields used for gray scale (i+1) is the same or greater than the number of subfields used for gray scale i, and generating a third gray scale arrangement including gray scales (n+p) to (m+p) by adding a weight p of the (j+1)th subfield to the first gray subfield arrangement including the gray scales n to m.

Abstract: Disclosed herein is a method and apparatus for driving a plasma display panel, which improves contrast characteristics and preventing a low discharge making a cell non-luminous at a specific gray scale.

Abstract: The method to reduce image sticking in a plasma display panel (PDP) includes four steps. There is converting a relationship between gray level and brightness of an input signal into a linear relation by a converter. Next, there is recording an image with a static image detector at time t using a frame buffer, and after a period of time ?t, comparing the image at time t with the image at time t+?t, thereby identifying static or dynamic images in the pixel. Then, there is recording a gain of every pixel by a brightness regulator using an image gains memory buffer zone, the gain being regulated according to detection results of the static image detector. Finally, there is improving gray level performance of output images by a gray level promoter and brightness converter. Thus, method actively detects static pixels and reduces brightness in the static region for minimized image sticking.

Abstract: A method and apparatus of driving a plasma display panel for preventing a damage of a driving integrated circuit caused by an abnormal discharge generated from a non-display area is disclosed. In the apparatus, a plurality of drivers drives driving electrodes of an active area and dummy electrodes of a non-display area. A current limiter is positioned between any at least one of the dummy electrodes and the drivers to limit currents flowing in the dummy electrodes.

Abstract: An improved method of testing and inspecting a plasma display panel. In a plasma display panel, a plurality of cells are formed at an intersection of each electrode disposed in a row direction and in a column direction of the panel. A field is formed of a plurality of sub-fields, and the combination of the sub-fields enables the panel to have a gradation display. In the inspection method, an address pulse voltage is not applied to a target cell to be inspected in a predetermined sub-field, but is applied to at least one cell of the cells adjacent to the target cell, and the address pulse voltage is applied to the target cell in the successive sub-field. If the barrier ribs of the target cell have an imperfection, wall charges of the cell are affected by the discharge occurred in an adjacent cell, and the target cell fails to light on in the successive sub-field. The inspection method can thus detect lighting failure caused by defective barrier ribs.

Abstract: An electrode drive circuit of a plasma display device comprises: a scan driver provided with plural drivers including first and second switching elements and first and second diodes; a capacitor connected between the high potential side terminal and the low potential side terminal of the scan driver; a voltage supply circuit for selectively supplying plural voltages relating to the positive and negative voltages of the reset pulse and the voltage of a scan pulse to the low potential side terminal of the second switching element; and a negative reset switch and a resistor connected in series between the high potential side terminal of the first switching element and a ground terminal, wherein the reset pulse of negative polarity is applied by turning on the negative reset switch in a state where the capacitor is charged with the negative voltage of the reset pulse.

Abstract: In many cases it is not possible to reproduce enough video levels on a PDP due to timing issues or a specific solution against the false contour effect. In such cases dithering is used to render all required levels. In order to reduce the visibility of the dithering noise there is performed a common change of the sub-field organization together with a modification of the input video data through an appropriate transformation curve based on the human visual system luminance sensitivity (Weber-Fechner law).

Abstract: The present invention discloses a method and an apparatus for calculating an optimal Average Picture Level (APL) in a plasma display of asymmetric cell configuration wherein each red, green and blue cell has asymmetric size and a plasma display using the same.

Abstract: According to an exemplary driving method of a plasma display panel of the present invention, waveforms having a reset function, an address function, and a sustain discharge function are applied to a scan electrode while sustain electrodes are biased at a ground voltage. A board for driving the sustain electrodes and a switch for supplying a ground voltage is eliminated and accordingly manufacturing cost of driving boards is reduced. Various circuits for generating the desirable waveforms and simplifications that do not compromise the effectiveness of the circuits are also presented.

Abstract: The invention relates to a liquid crystal display device used for a display part of an information equipment and a driving method thereof, and has an object to provide a liquid crystal display device in which excellent viewing angle characteristics can be obtained and a driving method thereof. When a relatively high level data voltage is applied to a gate electrode of a TFT, a driving voltage is applied to a liquid crystal layer for a long time and a white display is realized. When a relatively low level data voltage is applied to the gate electrode of the TFT, the driving voltage is not applied to the liquid crystal layer, and a black display is realized. When an intermediate data voltage between the high level and the low level is applied to the gate electrode of the TFT, the TFT keeps an on state for a time determined by a time constant depending on a capacitance and a resistance. The driving voltage is applied to the liquid crystal layer for the on time.

Abstract: A plasma display panel (PDP) that has a T-shaped electronic structure or an electrode structure with adjacent parts of the scan electrode and the sustain electrode being broad, and parts coupled to the bus electrodes being narrow in a like manner to the T-shaped electrode structure is provided. The PDP has various discharge modes according to magnitudes of sustain discharge voltages. A frame is divided into a plurality of subfields with respective weights and is driven in the PDP. The subfields with low weights use low sustain discharge voltages to perform a discharge with a small quantity of emitting light, and the subfields with high weights use high sustain discharge voltages to perform a discharge with a big quantity of emitting light, thereby increasing representation performance of low gray scales.

Abstract: An image display method and image display apparatus reduce dynamic false contours with sufficient gradations maintained even in a portion where large dynamic false contours occur. The image display method and image display apparatus convert a gradation level of a non-target pixel to a display-use gradation level to display. For a target pixel, a first diffusion process, in which the gradation level is converted to a first gradation level, which is an average of (n) (n is an integer of two or greater) levels of gradations selected from the display-use gradation levels, and the first gradation level is averaged spatially and/or chronologically using the (n) levels of gradations, suppressing dynamic false contours with sufficient gradations maintained.

Abstract: A method of improving response time of a display element in a display is disclosed. According to the method, a command input is provided that represents a desired response of the display element. The command input is modified, using a compensation function, to produce a command output to be sent to the display element. The compensation function uses the command input and a modeled luminance of the display element in a present state and at least one previous state to compute the command output. The command output is transmitted to the display element.

Abstract: Positive and negative sustain discharge voltages of equal magnitude are alternately applied to a scan electrode while biasing the sustain electrode at 0 V during a sustain interval. The positive sustain discharge voltage is applied through the first end of the scan electrode, and the negative sustain discharge voltage is applied through the second end of the scan electrode. The present invention may remove a brightness variation which may occur toward a direction the scanning electrode extends.

Abstract: The present invention relates to a driving method and apparatus of a plasma display panel. The driving method including the steps of: checking whether or not a first input grayscale data can be expressed through a certain pixel on the panel; in case the first grayscale data cannot be expressed, outputting a second grayscale data adjacent to the first grayscale data; and respectively multiplying erroneous data corresponding to a difference between the first grayscale data and the second grayscale data with preset coefficient values to diffuse the multiplied result to a plurality of pixels adjacent to the pixel, wherein before the erroneous data are respectively multiplied with the preset coefficient values, a random value is multiplied to at least one coefficient value among the plurality of coefficient values.

Abstract: A field sequential pulse width modulated display system comprises a digital micromirror device (DMD) having a plurality of micromirrors that each selectively pivot to reflect light onto a screen to illuminate a corresponding pixel. A driver circuit controls the DMD responsive to sequences of pulse width segments formed by a processor. The processor actuates at least one pulse in a first pulse width segment for a given color to increase pixel brightness with a range lying between first and second pixel brightness values. To further increase pixel brightness, the processor actuates at least one pulse within additional pulse width segments associated with the same given color to increase pixel brightness above the second brightness boundary. The pulses within the additional segments are actuated unequally so that the additional pulse width segments closest in time to the first segment (i.e.

Abstract: A method and apparatus for driving a plasma display panel in which discharge cells are formed by first, second, and third electrodes, has a frame divided into a plurality of subfields, each of which includes a reset period, an address period, and a sustain period. In the reset period, a voltage at the first electrode is modified from a first voltage to a second voltage, the first electrode is floated; and the voltage at the first electrode is gradually reduced to a third voltage.

Abstract: A display device operating in accordance with a sub-field process, includes a first block which varies the number of bits of a received image signal, a second block which calculates an average picture level (APL) of images defined by the image signal transmitted from the first block, a third block which converts the image signal into sub-field coding data, and outputs the sub-field coding data to a display panel, and a fourth block which receives the average picture level from the second block, converts the received average picture level to the number of sustaining pulses, transmits the number of sustaining pulses to the display panel, and transmits the number of sustaining pulses to the third block, wherein the third block selects the number of bits of a signal to be input thereinto, in accordance with the number of sustaining pulses received from the fourth block.

Abstract: A disclosed plasma display apparatus and a plasma display panel driving method provide improved luminance while preventing decrease in resolution. In the plasma display apparatus, which is adapted to the display of an interlace signal, the maximum number of sustain pulses associated with the emission of light that can be made in one field is calculated, based on the vertical synchronization signal frequency of the input signal. A display load factor of the input signal in the one field is calculated and, based on the calculated display load factor, a target number of sustain pulses in the one field is determined. Based on a relationship between the target number of sustain pulses and the maximum number of sustain pulses, an emission luminance ratio of a sub-display line to a main-display line in the one field is determined.

Abstract: The plasma display includes a controller and a driver. The controller divides one frame into a plurality of subfields, and establishes address and sustain periods in the respective subfields according to a subfield load ratio indicating a ratio of light emitting cells in the respective subfields. The driver selects a light emitting cell among the plurality of discharge cells during the established address period and sustain-discharges the light emitting cell during the established sustain period.

Abstract: A display apparatus, which displays a color image by controlling the number of emissions or the intensity thereof in accordance with primary color video signals input thereto, has a detection portion and a white balance correction portion. The detection portion is used to detect the number of emissions or the intensity, and the white balance correction portion is used to correct white balance by adjusting the amplitudes of the primary color video signals in accordance with the detected number of emissions or the detected intensity. Therefore, correct white balance can be maintained regardless of the number of emissions or the intensity of emission.

Abstract: A display includes a display module, a light source, a light source driving circuit, a display driving circuit, and an optical sensor. The optical sensor is installed next to the light source for detecting the luminance and color temperature of the light source. The optical sensor is coupled to the display driving circuit for generating a feedback signal to the display driving circuit according to the luminance and the color temperature of the light source. The display driving circuit drives the display module to display an image according to a received image signal and updates the data of the image signal according to the feedback signal so as to adjust the luminance and the color temperature of the image.

Abstract: A technique for driving a PDP, which includes scan and sustain electrodes arranged in pairs, data electrodes arranged alternately with the scan electrodes, and sub-fields for one TV field to display a multi-gradation, includes applying a reset pulse voltage to the sustain electrodes, applying a first voltage alternately to the scan electrodes and the sustain electrodes to cause a sustain discharge, and after applying a second voltage to the sustain electrodes or removing part of the first voltage applied to the sustain electrodes, applying third and fourth voltages to the scan electrodes and the data electrodes, respectively, before applying the first voltage, to erase wall charges in cells defined by the sustain electrodes, the data electrodes, and the scan electrodes.

Abstract: A method of driving a plasma display panel (PDP) is provided. In the method, the number of sustain pulses to be applied during a sustain period for each subfield in a frame is calculated. In order to achieve better image quality, fractional parts of the number of calculated sustain pulses is not disregarded but used by adding this fractional part to the appropriate count for a comparable subfield in a subsequent frame. By including this calculated fractional part in the calculations, a better image quality can be realized where there is less distortion.

Abstract: A driving apparatus of a plasma display panel (PDP) and a method for displaying pictures on the plasma display panel, which are capable of increasing the ability to express a low gray scale. Common non-emitted sub-fields are detected, using picture signal data having the maximum level of the gray scale, of all input picture signal data within one frame of the input picture signal data. Sub-fields having higher weights are divided into a plurality of sub-fields having lower weights and the plurality of sub-fields having lower weights are rearranged as sub-fields for expression of gray scale, corresponding to the number of non-emitted sub-fields. In addition, the number of sustains corresponding to the rearranged sub-fields are generated.

Abstract: An apparatus and method for driving a plasma display panel. In an idle period, a lowest voltage is applied to each circuit of a driving board of a plasma display panel so that a bootstrap capacitor of a switch driving circuit may enter a chargeable state. Therefore, it is possible not only to make the capacity of the bootstrap capacitor of each circuit small, but also to effectively prevent an abnormal discharge or an abnormal operation of each circuit when an abnormal image is inputted.

Abstract: In a display device performing multiple gray level display using a sub-field drive method, an operation rate of a scan driver and a data driver is reduced and power consumption in the circuits are reduced. When 28 levels of gray level display is performed with 8 bits of video data, one field is equally divided by 8 into eight sub-fields to generate a first sub-field SF0 through an eighth sub-field SF7. Each of the sub-fields SF0 through SF7 has an equal length of sub-field period to each other. And a line-sequential addressing is adopted in addressing pixels so that each line of video data is written-in collectively. Addressing operation of the pixels and light emitting operation of the pixels are performed in parallel. Each of addressing periods AP0 through AP7 in each of the sub-fields is approximately equal to the sub-field period, that is a period of one field divided by 8.

Abstract: The invention relates to a driver for a plasma display panel. According to the invention, in order to reduce the current loops during the sustain of the display cells, a novel driver architecture is proposed. The switches of the sustain circuit, together with the switches, are disposed next to one another on the circuit board. In addition, the connectors accessing the display electrodes are placed, at the periphery of the board, on the same edge.

Abstract: A method of switching a high-side switch of a plasma display panel (PDP) scan circuit in zero-voltage-switching mode. The scan circuit contains a high-side switch and a low-side switch. By controlling the voltage potential difference across the high-side switch, the high-side switch of the PDP scan circuit can operate using soft switching or in zero-voltage-switching (ZVS) mode. The switching loss of scan ICs and the switching noise from scan ICs will therefore be reduced.

Abstract: A plasma display device, which is capable of improving a discharge efficiency of a plasma display panel by increasing a partial pressure of Xe. When the partial pressure of Xe is increased, a proportion of (Xe—Xe)* dimer emitting a 147 resonance line is higher than that of Xe* monomer emitting a 173 nm molecular beam. Particularly, when the partial pressure of Xe is above 10%, the discharge efficiency is improved by setting a frequency of a sustain discharge pulse applied to scan electrodes and sustain electrodes alternately during sustain period above 300 kHz.

Abstract: A method of driving a panel and a plasma display unit is provided, wherein one field comprises a plurality of subfields, each having an addressing period for producing an address discharge selectively in any of discharge cells, and a sustaining period for producing a sustain discharge by applying a number of sustaining pulses corresponding to a weight of brightness in the discharge cell where the address discharge has been produced. Provided therein is a sustaining pulse generator circuit comprising a power recovery section for rising or falling the sustaining pulse by producing resonance between an inter-electrode capacitance of a display electrode pair and an inductor, and a clamping section for clamping a voltage of the sustaining pulse at a predetermined potential, wherein the power recovery section is used to set twice a time of rising the sustaining pulse to become equal to or longer than a duration of the sustaining pulse.

Abstract: The picture quality on a plasma display panel shall be improved when the contrast and/or the brightness are reduced. This is achieved by estimating the reduction of the dynamic occurring in the front-end of the data processing of the plasma display device and by compensating it in the back-end. Specifically, the gain and/or offset of the video input data are adjusted and the power level of the adjusted video data is measured. The resulting power level information is updated on the basis of an attenuation information. The updated power level is used for the power management and the level of the video data being reduced in the front-end is increased on the basis of the attenuation information. Thus, the dynamic of the video and, as a result, the picture quality are improved.

Abstract: The present invention relates to a plasma display panel, and more particularly, to a method and apparatus for driving a plasma display panel. According to a first embodiment of the present invention, there is provided a method for driving a PDP including the steps of dividing two frame data items into three frame data items; and providing the divided frame data items to the PDP. According to a first embodiment of the present invention, there is provided a method for driving a PDP including the steps of dividing two frame data items into three frame data items; and providing the divided frame data items to the PDP. The method and apparatus for driving a PDP according to the present invention can reduce large area flicker and dynamic false contour noise in a high-resolution PDP.

Abstract: A claimed multiple mode switch includes an input signal interface for receiving first and second input signals and producing a combined input signal; a driving circuit for receiving the combined input signal and producing driving signals accordingly; a resistor mode circuit electrically connected to a first output of the driving circuit, to a first node, and to a second node for enabling the multiple mode switch to operate in variable resistor mode or in large resistor mode; a fully-on mode circuit electrically connected to the second input signal, the first output of the driving circuit, and the second node for enabling the multiple mode switch to operate in fully-on mode; and a power switch electrically connected to the first node, the second node, and a third node for controlling switching of the multiple mode switch between off mode, fully-on mode, and variable resistor mode or large resistor mode.

Abstract: An image display apparatus using a display panel such as a plasma display panel having two illumination states aims to widen a dynamic range by increasing a ratio of maximum to minimum luminance reproducible on the same screen. In the image display apparatus, one TV field period is divided into a plurality of sub-fields which respectively have luminance weights and are arranged in order of time, and a gray-scale image is displayed by selecting a combination of sub-fields for each pixel and sustaining a light emission state of each pixel during the selected sub-fields, wherein when arranged in ascending order of luminance weight, the plurality of sub-fields include at least one sub-field whose luminance weight is one-half of a luminance weight of the next sub-field.

Abstract: A plasma display device is provided which expresses a video with gradations by selecting each of a plurality of subfields forming one field, each of the subfields having a weighted number of sustain pulses. A sustain pulse number calculation unit calculates a display load factor of an input video signal and calculates a total number of sustain pulses of one field according to the display load factor. A gradation number selection unit selects a gradation number being a sum of weights of all of the subfields according to the calculated total number of sustain pulses.

Abstract: There is disclosed a method and apparatus of driving a plasma display panel that is adaptive for reducing discharge delay upon reset discharge. A driving method and apparatus of a plasma display panel according to an embodiment of the present invention applies a plurality of pulses to the plasma display panel for the reset period in order to reduce a discharge delay.

Abstract: A technique capable of suppressing or preventing generation of flickers (blinks) by a sustain period control as well as capable of ensuring or enhancing display quality in a PDP device. The PDP device adjusts a sustain pulse of the sustain period for every subfield by selecting a combination of one or more than one cycle so that start and end timings of a field in fields before and after change are almost the same according to a display load ratio of the subfield of the field. Field weighted emission center positions then becomes almost the same, and flickers and the like are suppressed.

Abstract: A method of driving a plasma display panel including discharge cells, each at an intersection of a scan electrode and a sustain electrode, and a data electrode. One field period is divided into a plurality of sub-fields, each having an initializing period, writing period, and sustaining period. The sustaining period of at least one sub-field has a first sustaining period and second sustaining period. In the first sustaining period, a sustain pulse has a first leading edge duration. In the second sustaining period, the sustain pulse has a second leading edge duration shorter than the first leading edge duration. The second sustaining period is included at least at the end of the sustaining period.

Abstract: Disclosed is a PDP driving method having a misfiring erase period between reset and address periods. Large amounts of positive and negative charges are respectively formed on scan and sustain electrodes because of an unstable reset operation in the reset period. Because of the charges, discharging can occur between the scan and sustain electrodes in the sustain period even without addressing in the address period. In the misfiring erase period, a voltage is applied between the scan and sustain electrodes to generate discharging and respectively form negative and positive charges on the scan and sustain electrodes. An erase pulse is then applied to erase the negative and positive charges respectively formed on the scan and sustain electrodes.

Abstract: An image display method for allowing an image display device having a large number of pixels arrayed in a planar form to perform an image display by forming one field period from plural sub-fields for which luminance weights to be displayed are determined, and choosing plural luminances among displayable luminances as luminances for display by combining the luminance weights of the sub-fields, so that the respective pixels are controlled not to emit light or to emit light in each sub-field correspondingly to the luminances for display to be displayed. At least one threshold value is set, and when a pixel is allowed to emit light at a luminance for display at or higher than a first threshold value, which is the smallest threshold value, the pixel is controlled not to emit light constantly or to emit light constantly in a sub-field having the smallest luminance weight.

Abstract: A method of adjusting the brightness of a display device is provided. The method includes providing a plurality of saturated level-adjust voltages to various level adjustments of the display device when the central brightness is saturated. Then, a computation of the saturated level-adjust voltage of each level adjustment is carried out to obtain a display voltage of each level adjustment. Thereafter, a computation of the saturated level-adjust voltage, a common voltage and the display voltage of each level adjustment is carried out to obtain a feed-through voltage for each level adjustment. After that, a computation of the feed-through voltage and the saturated level-adjust voltage of each level adjustment is carried out to obtain a liquid crystal capacitance value for each level adjustment. Finally, a simulation of the liquid crystal capacitance value of each level adjustment is carried out to obtain an optimized level-adjust voltage for each level adjustment.

Abstract: The invention provides a semiconductor display device with less generation of a pseudo contour while the drive frequency of a driver circuit is suppressed. Furthermore, the invention provides a semiconductor display device with less generation of a pseudo contour while the decrease in image quality is suppressed. A semiconductor display device comprises a table storing data for determining a relationship between the gray scale level of a video signal and a subframe period for light emission in the plurality of subframe periods, a controller for changing a video signal in accordance with the data and outputting, and a panel whose pixel gray scale level is controlled in accordance with the outputted video signal. The number and the length of the plural subframe periods for each gray scale level of 2 or more are determined in accordance with a subframe ratio RSF which is calculated in accordance with a sharing ratio Rsh determined by the frame frequency.

Abstract: According to the present invention, a plasma display apparatus, which represents the luminance of one frame in accordance with a combination of plural sub-frames having luminance levels corresponding to a plurality of weighted values, additionally includes a sub-frame having a luminance level lower than the minimum gray scale level of luminance which can be represented by the number of bits in the input video data. Such plasma display apparatus turns on a desired combination of the sub-frames so as to increase the resolution of the luminance without increasing the conventional number of gray scale levels included in the input video data. In a preferred embodiment, especially when the added smaller luminance sub-frame is included in a combination of sub-frames for a low luminance area, the resolution of the gray scale of the low luminance area can be increased, and the representation of gray scale can be enhanced in a low luminance area to which the sight of a person is more sensitive.