KR20020005958A - Display device for generating half tone pseudoly and method of processing image signal - Google Patents

Abstract

PURPOSE: Display device for creating intermediate gradation levels in pseudo manner and imaging signal processing method are provided to realize a display device and an image signal processing method, which generate intermediate gradation levels in a pseudo-manner and which realize an image display having a more natural luminance change without undergoing the limitation of the number of gradation bits of input image data. CONSTITUTION: The device comprises an image output section (display section)(2) formed of an LCD, a PDP, an EL display, a CRT, or the like, a detection circuit (gradation change detection means)(3), and a conversion circuit (image data conversion means)(4). This display device(1) is capable of realizing the equivalent of a 9-bit gradation display in a pseudo-manner.

Description

DISPLAY DEVICE FOR GENERATING HALF TONE PSEUDOLY AND METHOD OF PROCESSING IMAGE SIGNAL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and in particular, a liquid crystal display device that performs display by image data having a predetermined number of gradations, a plasma display device (hereinafter referred to as a plasma display panel), and electroluminescence (hereinafter referred to as PDP). EL display device) and an image signal processing method applicable to these display devices and the like.

Recently, display devices such as liquid crystal displays (hereinafter referred to as LCDs) have been used in various fields. In general, a color LCD has a 6-bit or 8-bit digital driver for each color of R (red), G (green), and B (blue). For example, according to the LCD having an 8-bit digital driver, 256 gray scales can be displayed in each color, and approximately 16.7 million colors can be displayed as a whole. However, this level of LCD is sufficient performance for general purpose monitors for home use such as simple OA equipment, but insufficient performance for industrial monitors for medical use, broadcasting use, etc., and therefore the increase in gradation is desired.

For example, when 8-bit image data used in a video signal or the like is input to a conventional LCD having only a 6-bit digital driver, that is, the number of gradation bits that can be displayed on the display device is expressed by the image data input to the display device. When smaller than the number of gradation bits available, the non-displayable component (in this case, the lower two bits) in the image data at any one pixel is diffused to pixels adjacent to the periphery in the same screen frame (intraframe error diffusion). In this way, a method of artificially increasing the number of gradations in the display device is adopted. In addition, a technique called so-called frame rate control (hereinafter referred to as FRC), which expresses a halftone in a pixel by blinking an arbitrary pixel in every successive frame, is also adopted.

In recent years, the number of displayable gradation bits of a display device has also improved, and it has become standard to mount an 8-bit digital driver on an LCD attached to a PC or the like. Therefore, if 8-bit image data is input to an LCD having an 8-bit digital driver, it can be displayed without using the pseudo gradation processing technique described above. However, as described above, in the case of medical use, broadcasting, and the like, the original image data before entering the PC may be 10 bits, and in such a case, even if an LCD that can display only 8 bits of gray scale is used, the pseudo As a result, there is a request for displaying 10 bits.

In the case of an XGA (Extended Graphics Array) system LCD having a pixel number of one scanning line, a case where image data of a ramp waveform is displayed on one scanning line is assumed. In the case of the ramp waveform, the 8-bit image data expressing 256 gray levels has a gray level of 0 on one side of the scanning line, and increases the number of grays by 1 for every 4 pixels from one side to the other side, resulting in 255 on the other side. . When this type of display is performed, it is rarely a problem for home use, but for medical use, broadcasting, etc., since the degree of gradation change is large even with a change of 1 as the gradation number which is the minimum resolution of this LCD, the luminance change is changed. Even if the image data of ramp waveform that is the most gentle is, the boundary of the image may be confirmed.

In general, in order to pseudoly increase the number of gray level bits when the number of gray level bits of the display device is the same as the number of gray level bits of the image data, it is conceivable to use the above pseudo gray level processing techniques such as intraframe error diffusion and FRC. However, these techniques simply generate the halftones by mechanically calculating the lower bits of the image data, and as described above, they are not able to meet the demand for smoother gradient change.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is not limited by the number of gradation bits of input image data, and a display device for generating an intermediate gradation to realize image display with a more natural luminance change without being limited. It is an object to provide an image signal processing method.

1 is a block diagram showing an overall configuration of a display device of a first embodiment of the present invention;

2 is a block diagram showing a configuration of a detection circuit of the display device;

3 is a flowchart for explaining the operation of the detection circuit;

4 is a diagram showing the state of image data and various signals in the display device;

5 is a diagram showing the state of image data and various signals in the display device of the second embodiment of the present invention;

6 is a block diagram showing a configuration of a detection circuit of the display device;

7 is a block diagram illustrating another example of the detection circuit;

8 is a flowchart for explaining the operation of the conversion circuit;

9 is a view for explaining a display image in the display device of the first embodiment of the present invention;

10 is a flowchart for explaining the operation of the second embodiment of the present invention, and

11 is a flowchart for explaining the image signal processing method according to the third embodiment of the present invention.

※ Explanation of code for main part of drawing

1: display device 2: image output unit (display unit)

3: detection circuit (gradation change detection means) 4: conversion circuit (image data conversion means)

5: operation circuit 6: holding circuit

7: discrimination circuit

In order to achieve the above object, the display device of the present invention displays one screen on a display portion by a plurality of fields or frames, and these gradation bits when the number of gradation bits included in the image data and the number of gradation bits included in the display portion are the same. When displaying the number of gradation bits larger than the number in the display section, there is a gradation change of one gradation number among adjacent image data among plural image data input in succession in time, and a plurality of plural inputs before this gradation change. Gradation change detection means for generating a control signal when detecting that the gradation number of the two pieces of image data is the same and the gradation number of the plurality of image data input after the gradation change is received, and the control signal Before the gradation change in any one of two fields or in two adjacent frames in time Processing for converting the number of grayscales of the image data into the number of grayscales of the image data after the grayscale change, or the image data after the grayscale change in any one of two temporally adjacent fields or two frames temporally adjacent to each other. And image data converting means for performing at least one of the processing for converting the number of grayscales into the number of grayscales of the image data before the grayscale change.

Here, the number of gradation bits refers to the number of bits, such as 6 (bits) and 8 (bits), which indicate the gradation of the display unit and image data, as described in [Technical Field to which the Invention belongs and Prior Art of the Field]. Say. The "gradation number" refers to a data string consisting of 6 bits, 8 bits, and the like, for example, "11111111" (255 gray scales in decimal).

In the display device of the present invention, the gradation change detection means has a gradation change of one gradation number between adjacent image data among plural image data inputted continuously in time, and a plurality of gradation changes input before this gradation change. It is detected that the number of grayscales of the image data is the same and that the number of grayscales of the plurality of image data input after the change of grayscale is the same, and a control signal is generated at this time. "There is a gradation change of one gradation number between adjacent image data, the gradation number of the plurality of image data input before this gradation change is the same, and the gradation number of the plurality of image data input after this gradation change is the same" This refers to image data such as a part of a ramp waveform illustrated in the section of [Technical Problems to be Invented], for example, in which gradation is most gently changed.

Then, the image data conversion means receives the control signal output from the gradation change detecting means, and the gradation of the image data before the gradation change in any one of two temporally adjacent fields or in two frames temporally adjacent to each other. The process of converting the number to the number of gray levels of the image data after the change of the gray level, or the number of gray levels of the image data after the gray level change in any one of two temporally adjacent fields or two frames temporally adjacent to the gray level before the gray level change. At least one of the processes of converting the image data into the number of tones is performed. That is, the number of gray levels of the image data before the change of gray level is changed between the adjacent fields or frames to the number of gray levels after the change of gray level, or the number of gray levels of the image data after the gray level change is changed to the number of gray levels before the gray level change. One data is shifted between adjacent fields or frames. Then, in the human eye, the image data of the place where the number of gray scales is changed is confirmed as an intermediate gray scale of one gray scale or less. In this way, halftones are artificially generated to realize image display with a more natural luminance change.

At least any one of the above-described image data converting means, the process of converting the number of tones of one or two image data before the change of the tone or the process of converting the number of tones of the one or two image data after the change of the tone It is preferable to carry out.

This is because, for example, when three or more pieces of image data are to be converted, the processing circuit becomes complicated, and the circuit size also increases rapidly.

In addition, when a control signal is generated from the gradation change detection means for each of the image data of two pixels located in the same column of two adjacent rows in the display portion, the image data conversion means is configured to perform image data of the two pixels. It is preferable to change the number of gray levels of the image data before the change of the gray level or change the number of gray levels of the image data after the change of the gray level.

The reason is that if the timing of converting the number of gray scales in the pixels arranged in the column (vertical) direction among the plurality of rows (scan lines) constituting the screen is aligned before or after the gray scale change, This is because there is a case where flicker is seen in a direction, which is not preferable. In this case, therefore, the problem of flickering in the vertical direction is solved when one of the upper and lower pixels converts the number of gray levels before the gray level change and the other after the gray level change.

Similarly, when a control signal is generated from the gradation change detection means for each of the image data of two pixels located in the same row of two adjacent columns in the display portion, the image data conversion means is configured to perform image data of the two pixels. It is preferable to change the number of gray levels of the image data before the change of the gray level or change the number of gray levels of the image data after the change of the gray level.

This configuration eliminates the problem of seeing flicker in the lateral direction.

The image signal processing method of the present invention is an image signal processing method for forming an image signal by a plurality of fields or frames, the number of gradation bits of image data and the gradation bits of the receiving side receiving and processing image data. When the number is the same, when the receiving side performs the processing of receiving the number of gray bits larger than the number of gray bits, there is a change in gray level of one gray number among adjacent image data among a plurality of image data input in succession in time, Also, when it is detected that the number of grayscales of the plurality of image data inputted before this grayscale change is the same, and that the number of grayscales of the plurality of image data inputted after this grayscale change is the same, the two adjacent temporally adjacent to each other based on the detection result The image data before the gradation change in either one of the fields or two frames adjacent in time. A process of converting the number of grayscales to the number of grayscales of image data after the change of grayscale, or changing the grayscale number of the image data after the grayscale change in any one of two temporally adjacent fields or two frames temporally adjacent to each other. At least one of the processes for converting the previous image data into the number of tones is characterized.

In the image signal processing method of the present invention, there is a gradation change of one gradation number among adjacent image data among plural image data inputted in succession in time, and the plural image data input before the gradation change It is detected that the number of gray scales is the same and that the number of gray scales of the plurality of image data input after this gray scale change is the same. "There is a gradation change of one gradation number between adjacent image data, the gradation number of the plurality of image data input before this gradation change is the same, and the gradation number of the plurality of image data input after this gradation change is the same" This refers to image data such as a part of a ramp waveform illustrated in the section of [Technical Problems to be Invented], for example, in which gradation is most gently changed.

In addition, based on this detection result, the number of grayscales of the image data before the grayscale change is converted into the number of grayscales of the image data after the grayscale change in any one of two temporally adjacent fields or one of two temporally adjacent frames. At least any one of two fields temporally adjacent to each other or a process of converting the number of grayscales of the image data after the grayscale change to the number of grayscales of the image data before the grayscale change in any one of two temporally adjacent fields. One process is performed.

That is, the number of gray levels of the image data before the change of gray level is changed between the adjacent fields or frames to the number of gray levels after the change of gray level, or the number of gray levels of the image data after the gray level change is changed to the number of gray levels before the gray level change. One data is shifted between adjacent fields or frames. Then, in the human eye, the image data of the place where the number of gray scales is changed is confirmed as an intermediate gray scale of one gray scale or less. In this way, halftones are artificially generated to realize image display with a more natural luminance change.

Then, at the time of performing the image data conversion process, at least one of a process of converting the number of tones of one or two image data before the change of the tone or a process of converting the number of tones of the one or two image data after the change of the tone It is preferable to perform either treatment.

The reason for this is that, for example, when three or more pieces of image data are to be converted, the processing method becomes complicated, and the circuit size for realizing the same also rapidly increases.

When a control signal is generated for each of the image data of two pixels located in the same column of two adjacent rows on the receiving side, the number of gray levels of the image data before the gradation change is converted between the image data of the two pixels, or It is preferable to change the conversion of the number of gray levels of the image data after the gray level change.

The reason is that if the timing of converting the number of gray scales in the pixels arranged in the column (vertical) direction among the plurality of rows (scan lines) constituting the screen is aligned before or after the gray scale change, This is because there is a case where flicker is seen in a direction, which is not preferable. In this case, therefore, the problem of flickering in the vertical direction is solved when one of the upper and lower pixels converts the number of gray levels before the gray level change and the other after the gray level change.

Similarly, for each of the image data of two pixels located in the same row of two adjacent columns on the receiving side, the number of gray levels of the image data before the gray level change is converted between the image data of the two pixels, or It is preferable to change the conversion of the number of gray levels of the image data after the change.

This configuration eliminates the problem of seeing flicker in the horizontal direction.

Embodiment of the Invention

[First embodiment]

Hereinafter, a first embodiment of the display device of the present invention will be described with reference to FIGS. 1 to 4.

1 is a block diagram showing the overall configuration of the display device of this embodiment, FIG. 2 is a block diagram showing the configuration of a detection circuit, FIG. 3 is a flowchart for explaining the operation of the detection circuit, FIG. 4 is image data and various It is a figure which shows the state of a signal.

As shown in Fig. 1, the display device 1 of the present embodiment includes an image output section 2 (display section) made of LCD, PDP, EL, CRT, and the like, and a detection circuit 3 (gradation change detection means). And a conversion circuit 4 (image data conversion means). This display device 1 can pseudoly realize gradation display equivalent to 9 bits when, for example, the number of gradation bits of the input image data is 8 bits and the number of gradation bits that the image output unit 2 can display is 8 bits. will be.

In the case of this embodiment, the detection circuit 3 has a gradation change of one gradation number among adjacent image data among a plurality of image data inputted continuously in time, and the two images input before this gradation change. The control signal is generated when it is detected that the number of gray levels of the data is equal to each other and that the number of gray levels of the two image data input after this gray level change is the same.

As shown in FIG. 2, the detection circuit 3 includes an arithmetic circuit 5, a holding circuit 6, and a discriminating circuit 7. In the operation of the detection circuit 3, first, the calculation circuit 5 calculates the number of gray levels of the input image data (calculates the first derivative). Next, in the holding circuit 6, the calculation result of the gradation number sent from the calculation circuit 5 is stored and sent to the discriminating circuit 7. Next, the operation result sent from the holding circuit 6 in the determination circuit 7 is discriminated. Based on the discrimination result, control commands for data transmission and storage are sent to the holding circuit 6. A detailed operation will be described later.

The conversion circuit 4 receives the control signal from the detection circuit 3, and converts the number of gray levels of the image data before the gray scale change in any one of two adjacent frames in time, and the number of grays of the image data after the gray scale change. At least one of a process of converting the grayscale number of the image data after the grayscale change into a grayscale number of the image data before the grayscale change in either of two frames adjacent to each other in time. In the present embodiment, a configuration for converting the number of gray levels of image data between frames is illustrated, but it may be a configuration for converting the number of gray levels of image data between adjacent fields.

Hereinafter, the operation of the display device 1 having the above configuration, particularly the operation of the detection circuit 3, will be described with reference to FIG.

(Step S0): Set the values of N1 and N2 to 0, respectively, and start the operation.

(Step S1): It is judged whether or not the plurality of image data inputted in sequence is the same data value (the content means the number of gray scales, and the data value in this case is K). If the condition of this step S1 is satisfied (at least once in a row), the process proceeds to step S2, and if the condition is not satisfied (not one time in a row), the process returns to step S0.

(Step S2): In step S1, the successive number N1 of successive identical data values K is counted. Then, it is discriminated whether or not consecutive numbers N1 of the same data value K are equal to or larger than N1th of the threshold value. Here, N1th is an arbitrary value set externally, and in this embodiment, N1th = 2. If the condition of this step S2 is satisfied (two consecutive times), the process proceeds to step S3. If the condition is not satisfied (two consecutive times), the process returns to step S1 while maintaining the value of N1. .

(Step S3): When the data value of the continuously input image data is different (if the data value is not K, the data value in this case is L), the data value different from the data value K which has been the same continuously until now If the difference of L (= KL) is calculated and the difference is the minimum value of the input data (this minimum value refers to 1 (the number of gradations), not 0), the process proceeds to step S4. If the difference is not the minimum value (2 or more), the process returns to step S0.

(Step S4): Similarly to step S1, it is discriminated whether or not the plurality of image data inputted in sequence are the same data value continuously (at this time, whether or not the data value is equal to L, since it is L). If the condition of this step S4 is satisfied, the process proceeds to step S5. If the condition is not satisfied, the process returns to step S0.

(Step S5): Similarly to step S2, in step S4, the successive number N2 of the same data values L which are continuous is counted. Then, it is discriminated whether or not the consecutive number N2 of the same data value L is equal to or greater than N2th of the threshold value. N2th is also an arbitrary value set externally similarly to N1th, and in this embodiment, N2th = 2. If the condition of this step S5 is satisfied (two consecutive times), the process proceeds to step S6, and if the condition is not satisfied (two consecutive times), the process returns to step S0.

(Step S6): The control circuit 7 generates a control signal for data conversion where the data value changes from K to L, and outputs it to the conversion circuit 4. And the value of N2 is substituted into N1, and it transfers to step S1.

That is, in the display device 1 of the present embodiment, data is generated only when there is a gradation change (change in one gradation) of the minimum resolution while the gradation continues to a certain degree (which is constant by at least three data before and after the gradation change). Since pseudo-gradation is generated by the conversion, even if there is a change in the tone, if it is a change in the tone of 2 or more, the data conversion is not performed. As a result, the effect that the luminance change becomes more gentle when there is a gentle luminance change is obtained, and the waveform of the original data with the gray scale change of two or more gray levels is not broken.

FIG. 4 is a diagram showing data waveforms for explaining the operation of image data conversion based on gray scale change detection by the sequence shown in FIG. 3. Reference numerals 301 to 306 denote respective image data input in time series (from 301 to 306) in the input signal, and 301, 302, and 303 are sets of the same data values (the values themselves may be arbitrary), 304, 305, and 306. This is the same set of data values. The difference between these two sets of data values is assumed to be the minimum value (number of grays) of the input data. The data value before 301 is different from the data value of 301, and both N1th and N2th set externally are 2.

When the image data of the input signal is sequentially viewed, when the data value of 301 is input, the operation sequence of FIG. 3 remains in the state of step S1.

Since the data values of 302 and 301 are the same at the time when the data value of 302 is input, the condition of step S1 is satisfied, and the flow proceeds to step S2. At this time, N1 = 1.

Since the data values of 303 and 302 are the same when the data value of 303 is input, the state of step S2 is maintained. At this time, since N1 = 2, the condition of step S2 is satisfied, and the flow proceeds to step S3.

Since the data values of 304 and 303 are different at the time when the data value of 304 is input, and the difference of these 304 and 303 data values is 1 of the minimum value, since the condition of step S3 is satisfied, it transfers to step S4.

Since the data values of 305 and 304 are the same when the data value of 305 is input, the condition of step S4 is satisfied, and the flow proceeds to step S5. At this time, N2 = 1 is set.

Since the data values of 306 and 305 are the same when the data value of 306 is input, the state of step S5 is maintained. At this time, since N2 = 2, the condition of step S5 is satisfied, and the flow proceeds to step S6.

In step S6, the control signal from the detection circuit 3 to the conversion circuit 4 from the detection circuit 3 to perform the process of converting the data value 304 after the data value has changed (after the gradation change) to the data value before the change. Is output.

In the conversion circuit 4, conversion processing is performed on 304 data values after data change. In this conversion process, for the input signals of 301 to 306, the output signal 1 (output signal of A frame) of 311 to 316, which are the same waveform as the input signal, and the data value of 304 after the data change are converted into the data value before the change. Output signals 2 (output signals of B frames) of one waveform 321 to 326 are generated, and these are alternately output in units of frames. Alternatively, the output signals 1 of 311 to 316 and the output signals 2 of 321 to 326 may be alternately output in field units.

Hereinafter, the operation of the conversion circuit 4 will be described with reference to FIGS. 4 and 8.

(Step SA0): Check the control signal from the detection circuit 3 and start the operation.

(Step SA1): It is determined whether the image data to be processed is an A frame or a B frame (the processing frame immediately after the start of operation is called an A frame).

(Step SA2-A): In the case of an A frame, conversion processing is not performed on the data values 301 to 306 of the input signal, and these are output as the data values 311 to 316 of the output signal 1.

(Step SA2-B): In the case of a B frame, only the data value 304 in the data values 301 to 306 of the input signal is converted into the data value 324 which is the same data value as the data value 303 before the grayscale change, and the output of these data after the conversion is performed. The data is output as the data values 321 to 326 of the signal 2.

Here, the data values 301 to 306 necessary for data conversion are stored in the memory of the conversion circuit 4 and are often used when necessary.

(Step SA3): It is determined whether or not the processing for the processing target frame is finished. If the processing for the processing target frame has not been completed, the process proceeds to step SA0, and the same process is repeated until the processing for the processing target frame ends. When the conversion is completed for the frame to be processed, the process proceeds to step SA4.

(Step SA4): The frame number is switched to the next frame number. Then, the process proceeds to step SA0 (when the processing frame is A frame, the next frame number is B frame, and when the processing frame is B frame, the next frame number is A frame).

When these output signals 1 and 2 are sent to the image output section 2, the display (identified characteristic) becomes equal to the output signal A of 331 to 336. That is, by the output signal 1 of the 314 and the output signal 2 of the 324 corresponding to the input signal of 304, the data of high and low data for one gradation are displayed alternately in units of frames or fields. Therefore, the input image data and the image output section 2 can be identified at a level smaller than the minimum resolution gradation level that can be displayed, that is, the 333 gradation level which is halfway between the 331 to 333 gradation level and the 335 to 336 gradation level. . Therefore, as compared with the gradation change when the input signals of 301 to 306 are displayed as it is, display having a more gentle gradation change can be obtained.

9A to 9C are diagrams for explaining a display image of the image output unit 2 in the display device 1, and FIG. 9A shows an output signal 1 (output signal of an A frame) 311 to 316. In this case, it is a display image, and 311A to 316A are images corresponding to output signals 311 to 316. Fig. 9B is a display image when output signal 2 (output signal of B frame) 321 to 326 is displayed, and 321B to 326B are images corresponding to output signals 321 to 326. Figs.

9C is a display image for comparison when the input signals 301 to 306 are displayed as they are, and 301N to 306N are images corresponding to the input signals 301 to 306.

In this way, when the display images of the A frame and the B frame are displayed alternately, it can be confirmed as a display having a more gentle gradation change than the gradation change as shown in Fig. 9C.

Alternatively, instead of performing the conversion process on the 304 data value after the data change as described above, the conversion process may be performed on the data value of the 303 input signal before the data change. In other words, when the data value of the 303 input signal before the data change (before the gradation change) is converted into the data value after the data change, the output signal 3 (output signal of B frame) of 341 to 346 is obtained. If the combination of the output signal 1 and the output signal 3 is displayed alternately in the frame unit or the field unit, the confirmation characteristic is the same as the output signal B of 351 to 356, and as in the case of the output signal A, a smoother gradation is obtained. The indication that the change is confirmed can be obtained.

Alternatively, as described above, instead of performing the conversion process on only the data value of 303 before the data change and the data value 304 of the data change, the conversion process may be performed on both front and rear sides. That is, on one frame (A frame) side, when the data value of 303 before data change (before gradation change) is converted into the data value after data change, output signal 4 of 361 to 366 is obtained, and the other frame ( On the B side), an output signal 5 of 371 to 376 is obtained by performing a process of converting the data value 304 after data change (after gradation change) to the data value before data change. When the combinations of these output signals 4 and 5 are alternately displayed in units of frames or fields, the confirmation characteristics are the same as those of the output signals C of 381 to 386, compared with the case of the output signals A and B. You can get an indication of a more gentle gradation change.

Second Embodiment

Hereinafter, a second embodiment of the display device of the present invention will be described with reference to FIGS. 5 to 7.

The basic configuration of the display device of this embodiment is the same as that of the first embodiment, and the difference from the first embodiment is that the same gray level change has occurred in two pixels located in the same column of two adjacent upper and lower rows in the display unit. In this case, only the specific data conversion method is illustrated. Therefore, hereinafter, detailed descriptions of the overall configuration of the display device, the configuration of the detection circuit, and the like will be omitted, and only the sequence of operation will be described with reference to FIG. 5 showing the state of image data and various signals.

In the present embodiment, the same input signals having the same reference numerals 401 to 406 shown in FIG. 5 are adjacent to two scanning lines adjacent to each other in the image output unit 2 (here n lines (even lines) and n + 1 lines (odd lines)). It is assumed to be inputted to). As a function of the detection circuit 3, the gradation change of the minimum resolution is detected in each scanning line based on the sequence shown in FIG. 3 similarly to the first embodiment, and when the gradation change occurs, the unique control signal is converted. Output to the circuit (4).

In the present embodiment, it is configured to switch in units of lines when the number of gradations is changed before and after the gradation change. For example, it is assumed to switch before the gray level change in the n line and after the gray level change in the n + 1 line. More specifically, this can be realized by setting the conversion circuit 4 described in FIG. 1 to a configuration in which a synchronization signal is input from the outside as shown in FIG. 6.

That is, the conversion circuit 4 of FIG. 6 has a data conversion circuit 8 and a conversion position adjusting circuit 9, and at the same time an image signal is input to the data conversion circuit 8, a synchronization signal is adjusted for the conversion position. It is input to the circuit 9. By inputting the synchronization signal to the conversion position adjusting circuit 9, a control signal corresponding to whether the line into which the image signal is input is an n line or an n + 1 line is output toward the data conversion circuit 8, so that the data conversion circuit 8 In the n line, the number of gray levels is changed before the gray level change, and in the n + 1 line after the gray level change. With such a configuration, even if there is the same gradation change of one gradation in the same column on two adjacent scanning lines, the position where the gradation number is changed in n lines and n + 1 lines is shifted by one data.

Hereinafter, the operation of the conversion circuit 4 of FIG. 6 will be described with reference to FIGS. 5 and 10.

(Step SB0): Check the control signal from the detection circuit 3 and start the operation.

(Step SB1): It is determined whether the image data to be processed is an A frame or a B frame (the processing frame immediately after the start of operation is an A frame).

(Step SB2-A): In the case of an A frame, it is subsequently determined whether the processing target line is an n line or an n + 1 line.

(Step SB3-A): When the processing target line is n lines, the conversion processing is not performed on the data values 401 to 406 of the input signal, and these are output as the data values 411 to 416 of the output signal 1.

(Step SB3-B): When the processing target line is an n + 1 line, only the data value 403 in the data values 401 to 406 of the input signal is converted into the data value 443 which is the same data value as the data value 404 after the gray scale change, and the conversion is performed. The following data are output as the data values 441 to 446 of the output signal 3.

(Step SB2-B): In the case of a B frame, it is subsequently determined whether the processing target line is an n line or an n + 1 line.

(Step SB3-C): When the processing target line is n lines, only the data value 404 in the data values 401 to 406 of the input signal is converted into the data value 424 which is the same data value as the data value 403 before the gradation change, and the output signal 2 Are output as the data values 421 to 426.

(Step SB3-D): When the process target line is an n + 1 line, output is performed as the data values 451 to 456 of the output signal 4 without performing the conversion process to the data values 401 to 406 of the input signal.

In steps SB3-A to SB3-D, the data values 401 to 406 necessary for data conversion are stored in the memory of the data conversion circuit and are often used when necessary.

(Step SB4): Upon completion of any one of (Step SB3-A) to (Step SB3-D), it is determined whether or not conversion to the line to be processed has been completed.

If the conversion to the line to be processed is not finished, the process proceeds to step SB0, and the same process is repeated until the conversion to the line to be processed is finished. When the conversion is completed for the line to be processed, the flow proceeds to step SB5.

(Step SB5): When the conversion is completed for the line to be processed, the line number is switched to the next line number.

(Step SB6): It is determined whether or not the processing for the processing target frame is finished. If the processing for the processing target frame is not finished, the process proceeds to step SB0, and the same process is repeated until the processing for the processing target frame is finished. When the processing is completed for the frame to be processed, the process proceeds to step SB7.

(Step SB7): Switch the frame number to the next frame number. The process then advances to step SB0 (when the processing frame is A frame, the next frame number is B frame, and when the processing frame is B frame, the next frame number is A frame).

Alternatively, instead of inputting the synchronization signal from the outside of the conversion circuit 4, as shown in Fig. 7, a timer for generating a control signal for switching the position of the change of the gray level in a fixed period (one horizontal period) inside ( Counter) 10 may be provided. Also in this configuration, the same operation as described above can be obtained.

Thus, by providing the structure which switches the position which changes gradation number in line units, the display apparatus of this embodiment can be implemented without storing line data.

On the other hand, it is also possible to provide a mechanism for storing line data on a line-by-line basis, comparing the data between the lines, detecting the gray level change in each line, and controlling the position at which the number of gray levels is changed based on this.

Next, the operation of image data conversion will be described with reference to Fig. 5 showing data waveforms.

When the control signal from the detection circuit is input, the conversion circuit 4 first outputs the output signals 1 (A) to 411 to 416 having the same waveform as the input signals to the n lines and the input signals of 401 to 406. Frame output signal) and output signals 2 (output signal of frame B) of 421 to 426, which are waveforms obtained by converting a data value of 404 after data change to a data value before change, and output these alternately in units of frames. . Alternatively, the output signals 1 of 411 to 416 and the output signals 2 of 421 to 426 may be alternately output in field units.

When these output signals 1 and 2 are sent to the image output section 2, the display (identified characteristic) becomes equal to the output signal A of 431 to 436. That is, by the output signal 1 of the 414 and the output signal 2 of the 424 corresponding to the input signal of the 404, the data and the low data for one gradation are displayed alternately in units of frames or fields. Therefore, the input image data and the image output section 2 can be identified at a level smaller than the minimum resolution gradation that can be displayed, that is, the 434 gradation level between the 431 to 433 gradation level and the 435 to 436 gradation level. .

On the other hand, for the n + 1 line, with respect to the input signals of 401 to 406, output signals 3 (output signals of the A frame) and 441 to 446, which are waveforms obtained by converting the data value of 403 before the data change to the data value after the change, The output signal 4 (output signal of B frame) of 451 to 456 which is the same waveform as the input signal is generated, and these are alternately output in units of frames. Alternatively, the output signals 3 of 441 to 446 and the output signals 4 of 451 to 456 may be alternately output in units of fields.

When these output signals 3 and 4 are sent to the image output section 2, the display (identified characteristics) becomes the same as the output signals B of 461 to 466. That is, by the output signal 3 of 443 and the output signal 4 of 453 corresponding to the input signal of 403, the data high and low data for one gradation are displayed alternately by frame unit or field unit. Therefore, the input image data and the image output section can be identified at a level smaller than the minimum resolution gradation that can be displayed, that is, the 463 gradation level between the gradation levels of 461 to 462 and the 464 to 466 gradation levels.

As a result, the characteristic confirmed in the image output section in line n is the same as the output signal A of 431-436, and the characteristic confirmed in the image output section in line n + 1 is the same as the output signal B of 461-466. That is, in the stage of the original input signal, the places where the same gradation change was located in the same column (listed in the vertical direction), when the parts of the output signals A and B are seen, are identified at the halftone level. The data are shifted horizontally.

As described above, when there is a change in gray level of one gray level in two pixels arranged vertically on two adjacent upper and lower scanning lines, the image identified in the intermediate gray level is also vertically arranged. Flicker may occur. However, in the case of this embodiment, since the location identified at the halftone level is shifted laterally by the scanning line, the flicker can be prevented from occurring.

In the present embodiment, the output signal 1 of the A frame has the same waveform as the input signal in the n line, and the output signal 2 of the B frame is converted from the input signal, while the output signal 4 of the B frame in the n + 1 line. In the same waveform as the input signal and converting the output signal 3 of the A frame from the input signal, the output signal is the same waveform as the input signal in the n-line and n + 1 lines. Although the frames to be converted are different from each other, instead of this configuration, a frame in which the output signal has the same waveform as the input signal and the frame in which the output signal is converted from the input signal may be the same in the n line and the n + 1 line, respectively.

Also, in the present embodiment, where there is a gradation change of the same gradation level in two pixels positioned in the same column of two adjacent upper and lower scanning lines in the image output section 2, the place identified at the intermediate gradation level Although the example which shifted | deviated horizontally by the line was demonstrated, the same can be said also about the direction which rotated 90 degrees horizontally and vertically. That is, in the case where there is a gradation change equivalent to one gradation in two pixels located in the same row (scanning line) of two adjacent signal lines extending in the vertical direction in the image output section 2, the gradation level The position identified in the above may be shifted in the vertical direction by the signal line. In this way, the flicker in the horizontal direction can be prevented as in the above.

[Third Embodiment]

An embodiment of the image signal processing method of the present invention will be described below with reference to FIG.

An embodiment of this image signal processing method includes changing the number of gradations and the number of gradations between adjacent image data of the input image data 101 that is the same as the input signal of FIG. 4, for example, adjacent data 302 and 303 of the input signal of FIG. On the basis of the detection process 102 for detecting and the detection result of the detection process 102, the number of gray levels of the image data 101 is converted, and the same processed image data 104 as the output signals 1, 2 of FIG. To an image data conversion process 103 for outputting the.

These detection process 102 and the image data conversion process 103 are processes applied to the display apparatus 1 shown in FIG. The detection process 102 is performed in the detection circuit 3, and the specific process is the same process as what was shown by the flowchart of FIG. In addition, the image data conversion process 103 is performed in the conversion circuit 4, and the specific content is the same process as what was shown by the flowchart of FIG. Therefore, detailed description of these detection process 102 and image data conversion process 103 is omitted here.

The technical scope of this invention is not limited to the said embodiment, It is possible to add various changes in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, an example of performing a process of converting the number of tones of one image data before the change of the gray scale or a process of converting the number of tones of one image data after the change of the gray scale has been shown. The number of gray levels of the data may be converted or the number of gray levels of the two image data after the gray level change may be converted. In addition, the number of data in which a constant gradation number continues before and after the gradation change may be other than three of the above embodiments, and can be appropriately set. In addition, the specific structure inside a detection circuit, a conversion circuit, etc. for implementing the logic of this invention is a matter which can be designed suitably.

The image signal processing method of the present invention can be applied not only to a display device but also to an image processing system, an image data relay device, and the like by a computer.

As described in detail above, in the display device of the present invention, when there is a change in gradation of minimum resolution (change of one gradation) while the constant gradation continues to some extent, image data near the gradation change is fielded. Alternatively, since the conversion is performed by a frame, the converted place is pseudo-identified as an intermediate tone of 1 or less gray scales, and image display having a more natural luminance change can be realized.

Claims (8)

When one screen is displayed on the display by a plurality of fields or frames, and when the number of gradation bits included in the image data is the same as the number of gradation bits included in the display unit, the display unit displays the number of gradation bits larger than these gradation bits. Among the plurality of image data input in succession in time, there is a gradation change of one gradation number between adjacent image data, and the gradation number of the plural image data input before this gradation change is equal to each other, and is input after this gradation change. Gradation change detection means for generating a control signal when detecting that the number of gradations of the plurality of image data is equal to each other, and the control signal, and receiving one of the two temporally adjacent fields or two frames temporally adjacent to each other. The image number after the gradation change is the number of gradations of the image data before the gradation change. The process of converting the data to the number of gray scales, or the number of gray scales of the image data after the gray scale change in any one of two temporally adjacent fields or two frames temporally adjacent to the gray scale of the image data before the gray scale change. And image data converting means for performing at least one of the processes for converting to a number. The image data converting means according to claim 1, wherein the image data converting means converts the number of gray levels of one or two image data before the gray level change, or converts the number of gray levels of one or two image data after the gray level change. And at least one of the processes described above. The image data converting means according to claim 1, wherein when a control signal is generated from said gradation change detecting means for each of image data of two pixels located in the same column of two adjacent rows in said display portion, And converting the number of gray levels of the image data before the change of the gray level or converting the number of gray levels of the image data after the change of the gray level between the image data of the two pixels. The image data converting means according to claim 1, wherein when a control signal is generated from said gradation change detecting means for each of the image data of two pixels located in the same row of two adjacent columns in said display portion, And converting the number of gray levels of the image data before the change of the gray level or converting the number of gray levels of the image data after the change of the gray level between the image data of the two pixels. An image signal processing method for forming an image signal by a plurality of fields or frames, wherein the number of gray scale bits of the image data and the number of gray scale bits of the receiving side for receiving the image data are larger than the number of gray scale bits. When the reception process of the number of gradation bits is performed on the receiving side, there is a gradation change of one gradation number among adjacent image data among the plurality of image data input in succession in time, and a plurality of plural inputs input before this gradation change. When it is detected that the number of gray scales of the image data is the same and the number of gray scales of the plurality of image data input after the change of the gray scale is equal to each other, based on the detection result, one of two fields that are adjacent in time or adjacent in time The gradation number of the image data before the gradation change in any one of two frames after the gradation change The process of converting the image data to the number of gray levels, or the number of gray levels of the image data after the gray level change in any one of two temporally adjacent fields or two frames that are temporally adjacent to the image data before the gray level change. An image signal processing method, characterized in that at least one of the processing for converting to the number of tones is performed. 6. The processing according to claim 5, wherein, when the image data conversion processing is performed, a process of converting the number of gray levels of one or two image data before the gray level change, or the number of gray levels of one or two image data after the gray level change And at least one of the processing for converting the data. The gray level change between the image data of the two pixels when the control signal is generated for each of the image data of the two pixels located in the same column of two adjacent rows on the receiving side. And converting the number of gray levels of the previous image data or converting the number of gray levels of the image data after the change of the gray level. 6. The gradation number of the image data before the gradation change between the image data of the two pixels is set for each of the image data of the two pixels located in the same row of two columns adjacent to the receiving side. Converting or converting the number of gradations of the image data after the gradation change is changed.