JP2010028576A - Image processor and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of an edge of a stationary body in a moving image obtained by converting moving image data constituted of F pieces of frames per unit time into moving image data constituted of 2F pieces of subframes per unit time. <P>SOLUTION: An LPF processing part 101 performs filter processing for removing high-frequency component of an input frame. A difference calculation part 102 performs processing for subtracting each pixel value of a frame after filter processing from each pixel value of the input frame, and generates a positive difference frame constituted of a difference pixel value of "0" or more and a negative difference frame constituted of a difference pixel value of "0" or less. A low-frequency subframe generating part 103 generates a low-frequency subframe by adding the negative difference frame to the frame after filter processing. A high-frequency subframe generating part 104 generates a high-frequency subframe by adding the positive difference frame to the input frame. A switching circuit 105 outputs two subframes of a low-frequency subframe and a high-frequency subframe whenever one frame is input. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for converting moving image data into moving image data having a frame rate higher than the frame rate of the moving image.

  A CRT has been used for many years as a moving image display device typified by a television receiver, but in recent years, a panel using a liquid crystal device is becoming mainstream. The characteristics of the liquid crystal device will be described with reference to FIG. In FIG. 7, the horizontal axis indicates time, and the vertical axis indicates pixel brightness. The frame rate here is 60 Hz. As shown in the figure, in the case of the liquid crystal device, the light emission is continued for 1/60 seconds. For this reason, the liquid crystal device is called a “hold type” device.

  The hold-type device has a drawback that it tends to cause blurring with respect to movement. FIG. 8 is an explanatory diagram thereof. The horizontal axis in FIG. 8 indicates the position on the screen, and the vertical axis indicates time. This figure is an example in which a rectangular waveform moves from the left to the right of the screen. When such a movement is followed by the eye, a state in which the pixels remain at the same position for 1/60 second with respect to the movement of the eye follows is a relative delay with respect to the movement. If the hold time is long, the delay is widened and is perceived as motion blur on the screen. The bottom diagram in FIG. 8 shows how the image is viewed when following, and indicates that a blur having a certain width is detected at the edge portion.

  As an example of measures against motion blur, there is a method of increasing the drive frequency and shortening the hold time. FIG. 9 is an example of displaying at 120 Hz, which is doubled. In order to obtain a double frame rate, there is also known a method of displaying an input image by dividing an image including a high frequency component and an image including only a low frequency component in the time direction. FIG. 10 shows the dynamic characteristics of an image driven and distributed by this method. As can be seen from comparison with FIG. 8, in the case of the display of FIG. 10, motion blur is greatly reduced.

  In addition, a field emission type display device has been developed as a device having light emission characteristics similar to those of a CRT. FIG. 11 is an explanatory diagram of the light emission characteristics of these devices. As in FIG. 7, the horizontal axis represents time, and the vertical axis represents pixel brightness. This type of display device emits light for an instant of 1/60 second, so it is called an “impulse type”.

  The impulse type device has a drawback that it is easy to perceive this flickering as flicker because it repeatedly emits light at a period of 1/60 seconds. Since flicker has a characteristic that it becomes more conspicuous as the area becomes larger, it tends to be a problem particularly in the recent trend toward larger screens of display devices.

  FIG. 12 shows the dynamic characteristics of the impulse type device. Unlike the hold-type characteristics, the greatest feature is that no motion blur that causes an afterimage occurs.

  As an example of flicker countermeasures, it is conceivable to increase the drive frequency. FIG. 13 is an example of displaying at double 120 Hz. In the case of the impulse type, the same brightness can be obtained by displaying twice the half of the brightness of one time.

  FIG. 14 shows dynamic characteristics when an image including a high frequency component and an image including only a low frequency component are divided and displayed in the time direction. If the same frame is simply displayed twice, it becomes a double image. However, by displaying only the high frequency side once, visual deterioration is suppressed only by blur caused by low frequency components.

  As described above, as a countermeasure against motion blur in a hold type display device or as a countermeasure against flicker in an impulse type display device, a method of distributing a frame image into two subframes by frequency components is effective.

As an example of a method for realizing the hold-type double speed drive, there is Patent Document 1. A part of the circuit configuration in this document is shown in FIG. For the input frame, the low-pass filter processing unit 1001 generates a subframe including only a low-frequency component. The generated subframe of only the low frequency component is temporarily stored in the frame memory 1007. The difference detection unit 1006 detects the difference between the input frame and the subframe including only the low frequency component generated by the low pass filter processing unit 1001, and extracts the high frequency component. By adding the high-frequency component generated here and the input frame, a subframe in which the high-frequency component is emphasized can be obtained. In the switching circuit 1005, the subframe including only the low frequency component and the subframe in which the high frequency component is emphasized are switched at a cycle of 120 Hz and sent to the subsequent processing. By alternately displaying the subframe excluding the high frequency component and the subframe emphasizing the high frequency component, the original frame image is reproduced when viewed at a time period of 60 Hz.
JP 2006-184896 A

  However, as described above, the apparent frame image obtained by combining the two subframes may not be the same as the original frame image. Hereinafter, a description will be given with reference to FIGS. FIG. 16A shows a waveform example of the input frame image. FIG. 16B shows an output waveform indicating the processing result of the low-pass filter processing unit 1001 of FIG. 15 for this input frame image. FIG. 16C shows an output waveform detected by the difference detection unit 1006 in FIG. Since it is a high frequency component, it takes a positive or negative value. FIG. 16D is a waveform obtained by adding a high frequency component (FIG. 16C) to the original input waveform (FIG. 16A). By alternately displaying the waveform of FIG. 16B and the waveform of FIG. 16C at a period of 120 Hz, the apparent waveform is theoretically the same as that of FIG. However, when the low luminance level portion of FIG. 16A is zero or a value close thereto, the waveform of FIG. 16D has a negative value. Since an image having a negative value cannot be displayed, the negative value is actually displayed as zero as shown in FIG. Then, actually, since FIG. 16B and FIG. 16E are displayed alternately, a human perceives the waveform as shown in FIG. This means that when there are white characters on a black background, the outline of the characters is perceived as a blurred image. That is, depending on the waveform of the input image, the image after the distribution process may not look the same as the original image and may be perceived as degradation.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a technique for suppressing deterioration of an edge of a stationary object in a moving image.

In order to solve this problem, for example, an image processing apparatus of the present invention comprises the following arrangement. That is,
An image processing apparatus that converts moving image data composed of F frames per unit time into moving image data composed of 2F frames per unit time,
Input means for inputting moving image data in units of frames;
Low-pass filter means for low-pass filtering the frame input by the input means;
When the difference pixel value obtained by performing the process of subtracting each pixel value of the frame after filtering by the low-pass filter means from each pixel value of the frame input by the input means has a negative value A positive difference frame composed of difference pixel values of “0” or more, which is “0”, is generated, and if the difference pixel value has a positive value, a difference pixel of “0” or less which is “0” Difference calculating means for generating a negative difference frame composed of values;
A low-frequency subframe generating means for generating a low-frequency subframe by adding the negative difference frame to the filtered frame obtained by the low-pass filter means;
A high-frequency sub-frame generating unit that generates a high-frequency sub-frame by adding the positive difference frame to the frame input by the input unit; and an output unit that outputs the low-frequency sub-frame and the high-frequency sub-frame.

  According to the present invention, a stationary object in a moving image obtained by converting moving image data composed of F frames per unit time into moving image data composed of 2F subframes per unit time. It is possible to suppress the deterioration of the edge of the.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
In the first embodiment, an example particularly suitable for a hold-type display device will be described.

  FIG. 1 is a block diagram of the image processing apparatus according to the first embodiment. This apparatus includes a control unit 150 that controls the entire apparatus, an LPF (low-pass filter) processing unit 101, a difference calculation unit 102, a low-frequency subframe generation unit 103, a high-frequency subframe generation unit 104, and a switching circuit 105. Is done. It should be noted that there are buffer memories for adjusting timing between the processing units shown in the drawing, but these are omitted.

  This apparatus will describe an example in which a moving image having a frame rate of F / sec is input from an input terminal, converted into a moving image having a frame rate of 2F / sec, and output. F / second is, for example, 60 frames / second. Therefore, every time a frame image is input, two subframes are generated and output. Since one of the two subframes is a subframe including a high frequency component, it is hereinafter referred to as a high frequency subframe. Since the other is a subframe including only a low frequency component, it is hereinafter referred to as a low frequency subframe.

  Note that the moving image input source is a video camera, but it may be moving image data after, for example, DVD media video decoding processing, and the type thereof is not limited.

  Further, in the embodiment, in order to simplify the description, it is assumed that the moving image data is monochrome. However, in the case of a color moving image such as R, G, B, etc., it is only necessary to perform the following processing for each color component, so it is not always necessary to be monochrome.

  First, low frequency subframe generation processing will be described.

  The low pass filter processing unit 101 performs filter processing for removing high frequency components. This filter does not particularly define a function, and may be, for example, a Gaussian function or a moving average or weighted moving average filter.

  FIG. 2A shows an example of an input waveform, and FIG. 2B shows a waveform of a low-frequency subframe that includes only a low-frequency component generated by the low-pass filter processing unit 101.

  The difference calculation unit 102 detects the difference value by subtracting the subframe after the low-pass filter processing from the input frame. Note that addition or subtraction between two frames refers to addition or subtraction of pixel values at the same coordinate position in the two frames. The same applies to the calculation between the difference frame and the frame described below.

  Now, the difference value calculated by the difference calculation unit 102 can take both a positive value and a negative value as shown in FIG. Since an image having a negative value cannot be displayed, as shown in FIGS. 2D and 2E, the positive value and the negative value are separated, and the absolute value is used for the negative value. To process. The frame indicated by the waveform in FIG. 2D is, in short, a positive difference frame composed of positive difference values greater than or equal to “0”, where the difference value is “0” when the difference value is negative. be able to. The frame shown in the waveform of FIG. 2E is a negative difference frame composed of absolute values of difference values equal to or less than “0”, where the difference value is “0” when the difference value is positive. It can be said.

  The above is defined more clearly as follows.

The difference pixel value of each pixel obtained by subtracting the filtered frame from the input frame is defined as D (x, y) using the coordinates (x, y). The value PD (x, y) of the coordinate (x, y) of the positive difference frame is obtained as follows.
PD (x, y) ← 0 when D (x, y) ≦ 0
PD (x, y) ← D (x, y) when D (x, y)> 0

Similarly, the value ND (x, y) of the coordinate (x, y) of the negative difference frame can be defined as follows.
When D (x, y) ≧ 0, ND (x, y) ← 0
If D (x, y) <0, ND (x, y) ← | D (x, y) |
(Where | V | represents the absolute value of V).

  The difference calculation unit 102 uses the negative difference frame (FIG. 2D) calculated as described above as the low frequency subframe generation unit 103 and the positive difference frame (FIG. 2E) as the high frequency subframe generation unit 104. Output to.

  The low-frequency subframe generation unit 103 performs a process of subtracting the negative difference frame from the low-pass filtered frame.

  If the difference calculation unit 102 outputs the negative difference frame without converting it to an absolute value, the low-frequency subframe generation unit 103 performs a process of “adding” the negative difference frame to the low-pass filtered frame. Just do it. This is because subtracting the absolute value of a negative value from a certain value is equivalent to adding a negative value to a certain value.

  As described above, the low-frequency subframe generation unit 103 performs processing for subtracting the waveform of FIG. 2D from the waveform shown in FIG. 2B, and the subtraction result is shown in FIG. The waveform becomes f). The frame indicated by the waveform in FIG. 2 (f) is a low-frequency subframe including only low-frequency components in the present embodiment.

  Next, generation of a high-frequency subframe will be described. The high-frequency subframe is generated by the high-frequency subframe generation unit 104.

  The difference calculation unit 102 supplies the positive difference frame in FIG. 2E to the high frequency subframe generation unit 104 as described above. The high-frequency subframe generation unit 104 adds the positive difference frame (FIG. 2E) from the difference calculation unit 102 to the input frame (FIG. 2A) and outputs the result. As a result, the high-frequency subframe generation unit 104 outputs a frame having a waveform as shown in FIG. A high-frequency subframe is output from the high-frequency subframe generation unit 104.

  In the switching circuit 105, when the frame rate of the input moving image is 60 Hz, for example, at a period of 120 Hz, the switching circuit 105 switches between the low-frequency subframe and the high-frequency subframe with a period of 120 Hz. Output alternately. Here, when a hold type display device is connected to the switching circuit 105, it will look like FIG. 2 (h) to human vision, and it is perceived as the same waveform as the input frame in FIG. 2 (a) at 60 Hz display. can do.

  The above is a monochrome example, but it can also be applied to a color image. In the case of a color display device, processing is often divided into three types of color components such as R, G, B, Y, Cb, and Cr. Therefore, in the case of R, G, and B, the above process may be performed on the luminance values of the respective color components. In the case of Y, Cb, and Cr, it is sufficient to perform only the luminance component Y for human visual sensitivity.

  Next, the processing content of the control unit 150 will be described using the flowchart of FIG. 3 and the processing waveform example of FIG.

  First, in step S301, the control unit 150 performs necessary initial settings. The static characteristics of the low-pass filter processing unit 101 are set at this stage. In step S302, a frame image is input. In the waveform example, FIG. 2A corresponds to this. In step S303, low-pass filter processing by the low-pass filter processing unit 101 is performed. The processing for generating the waveform in FIG. 2B corresponds to this.

  Next, in step S304, the difference calculation unit 102 is caused to perform a process of subtracting the low-pass filtered frame from the input frame. The difference calculation unit 102 generates two difference frames. One is a positive difference frame that is “0” when the difference value has a negative value, and remains positive when the difference value is positive. The other is a negative difference frame that is “0” when the difference value has a positive value and remains negative when the difference value is negative. In the following description, it is assumed that the value of each pixel position in the negative difference frame is 0 or has a negative value.

  In step S305, the low-frequency subframe generation unit 103 performs low-frequency subframe generation processing. Specifically, a process of adding the negative difference frame from the difference calculation unit 102 to the frame from the low-pass filter processing unit 101 is performed. The generated low frequency subframe corresponds to the waveform of FIG.

  In step S306, the high frequency subframe generation unit 104 performs a high frequency subframe generation process. Specifically, a process of adding the positive difference frame from the difference calculation unit 102 to the frame input from the input terminal is performed. The generated high-frequency subframe corresponds to the waveform of FIG. The high frequency subframe compensates for the lost high frequency component in the low frequency subframe.

  In step S307, the switching circuit 105 determines the output timing of the low frequency subframe. When the output timing is reached, a low-frequency subframe is output in step S308. After outputting the low frequency subframe, in step S309, the output timing of the high frequency subframe is determined. If the timing is reached, a high-frequency subframe is output in step S310. Each subframe does not have to be displayed first. In the case of a hold-type display device, a low-frequency subframe is displayed during the first 1/120 second, and a high-frequency subframe is displayed during the next 1/120 second.

  Henceforth, the process from step S302 is repeated until it determines with completion | finish in step S311. The apparent waveform with a time average of 1/60 seconds is as shown in FIG. 2H, which is the same waveform as the input frame. Subframes can be displayed in a time shorter than 1/120 seconds by improving the response characteristics of the liquid crystal or controlling the backlight. The feature of the present invention that the apparently identical waveform is generated does not change at all.

[Second Embodiment]
Next, an example suitable for an impulse-type display device will be described as a second embodiment.

  FIG. 4 is a block diagram of the image processing apparatus according to the second embodiment. In FIG. 4, the low-pass filter processing unit 101 is the same as in FIG.

  Hereinafter, the second embodiment will be described with reference to the waveforms shown in FIGS.

  In the second embodiment, as in the first embodiment, a high-frequency subframe including a high-frequency component and a low-frequency subframe including only a low-frequency component are generated from an input image of one frame. First, the low-frequency subframe generation process will be described.

  The low pass filter processing unit 101 performs filter processing for removing high frequency components. This filter does not particularly define a function, and may be, for example, a Gaussian function or a moving average or weighted moving average filter. FIG. 5A shows an example of an input waveform, and FIG. 5B shows the result of low-pass filter processing by the low-pass filter processing unit 101.

  The difference calculation unit 402 subtracts the frame obtained by the low-pass filter process from the input frame. If the subtraction result is a positive value, “0” is output, and if the subtraction result is a negative value, a negative difference frame composed of the absolute value of the negative value is output. The waveform in FIG. 5C is a waveform output by the difference calculation unit 402.

  The subtraction unit 401 performs a process of subtracting the negative difference frame (FIG. 5C) generated by the difference calculation unit 402 from the frame subjected to the low-pass filter processing (FIG. 5B). As described in the first embodiment, if the difference calculation unit 402 does not perform conversion to the absolute value when generating a negative difference frame, the difference calculation unit 402 replaces the subtraction unit 401 with an addition unit. Which is technically equivalent.

  Next, the distribution ratio processing unit 403 corrects the image data from the difference negative value subtraction unit 103 in accordance with the ratio of light emission of the two subframes. In order to make it difficult to perceive flicker, it is desirable that the difference in brightness between the two subframes is small. Therefore, here, an example in which distribution is performed according to a multiplication coefficient of less than 1 (in the embodiment, multiplication coefficient = 0.5 = 50%) will be described. That is, the distribution ratio processing unit 403 multiplies each pixel of the image data from the subtraction unit 401 by a multiplication coefficient “0.5” according to the ratio of light emission of the two subframes.

  FIG. 5E shows a waveform obtained by multiplying the waveform of FIG. 5D by “0.5”. The image indicated by the waveform shown in FIG. 5E is a low-frequency subframe. That is, the subtraction unit 401 and the distribution ratio processing unit 403 function as a low frequency subframe generation unit in the second embodiment.

  Next, a method for generating a high-frequency subframe will be described.

  The high-frequency subframe generation unit 404 performs processing for subtracting the low-frequency subframe from the input frame to generate and output a high-frequency subframe. FIG. 5F shows the waveform of this high-frequency subframe.

  In the switching circuit 105, when a desired timing, for example, when the frame rate of the input image is 60 frames / second (60 Hz), two subframes are alternately selected and output at a period of 1/120 seconds (120 Hz). To do. When an impulse type display device is connected to the switching circuit 105, the low frequency subframe of FIG. 5 (e) and the high frequency subframe of FIG. 5 (d) are alternately displayed with a period of 120 Hz. A waveform image as shown in FIG. That is, it can be perceived as the same waveform as the input frame in FIG.

  Thus, although the hold type and the impulse type are different in the generation form of the subframe, the post-processing is performed so that the subframe does not take a negative value, which is a process common to the present invention.

  Next, the above process will be described with reference to the flowchart of FIG. 6 and the waveform example of FIG.

  First, in step S601, the control unit 150 performs necessary initial settings. The static characteristics of the low-pass filter processing unit 101 are set in advance here. In step S602, a frame image is input. An example of the waveform of the input image is shown in FIG.

  In step S603, the low pass filter processing unit 101 performs low pass filter processing. FIG. 5B shows a waveform obtained as a result of low-pass filter processing.

  Next, in step S604, the difference calculation unit 402 generates a negative difference frame by subtracting the post-filter frame from the input frame. The absolute value waveform of the negative value obtained by this difference calculation corresponds to FIG.

  In step S605, the subtraction unit 401 is caused to perform processing for subtracting the negative difference frame from the frame after the filter processing. In the waveform example, FIG. 5D obtained by subtracting FIG. 5C from FIG. 5B corresponds to this.

  In step S606, distribution processing by the distribution ratio processing unit 403 is performed. This is a part that determines what percentage of the low-frequency subframe consisting of only the low-frequency components is to be included. Here, the description will be made assuming that 50% is uniform regardless of the pixel value. This corresponds to multiplying the waveform of FIG. 5D by 0.5 to generate the waveform of FIG. The image indicated by the waveform in FIG. 5E is a low-frequency subframe.

  In the next step S607, the high frequency subframe generating unit 404 generates a high frequency subframe. Specifically, a process of subtracting the low frequency subframe from the input frame is performed. FIG. 5F shows a difference waveform as a result of subtraction, which is a high-frequency subframe.

  In step S608, the switching circuit 105 determines the output timing of the low frequency subframe, and outputs the low frequency subframe in step S609. In step S610 after outputting the low frequency subframe, the switching circuit 105 determines the output timing of the high frequency subframe, and outputs the high frequency subframe in step S611.

  Thereafter, the processing from step S602 is repeated until the end is determined in step S612.

  In the case of an impulse-type display device, a low-frequency subframe is displayed at a preset instant within the first 1/120 second, and a high-frequency subframe is displayed at a preset instant within the next 1/120 second. It will be. Each subframe does not have to be displayed first. As a result, the apparent waveform with a time average of 1/60 seconds is as shown in FIG. 5G, which is the same waveform as the input frame.

[Third Embodiment]
The example which processes the said 1st, 2nd embodiment with the computer program by a computer is demonstrated as 3rd Embodiment.

  FIG. 17 is a block diagram of a general computer (personal computer). As shown in the figure, this computer includes a CPU 2002 that controls the entire apparatus, a ROM 2003 that stores a BIOS and a boot program, a RAM 2004 for loading a work area of the CPU 2002 and an application program to be executed. The computer also includes a network interface 2005, an input device 2006 such as a keyboard and a mouse, an output device 2007 such as a display device, and an external storage device 2008 such as a hard disk. These components are connected to each other via a system bus 2001.

  When the power of the apparatus is turned on, the CPU 2002 loads the OS (operating system) in the external storage device 2008 to the RAM 2004 in accordance with the boot program stored in the ROM 2003, and starts the OS, whereby the apparatus performs information processing. Functions as a device. Thereafter, when the user operates the input device 2006 and gives an instruction to start an application for moving image conversion, the CPU 2002 loads the corresponding moving image conversion application program from the external storage device 2008 to the RAM 2004 and executes it. This apparatus functions as an image processing apparatus.

  When functioning as an image processing device, the CPU 2002 inputs, for example, one frame at a time from a moving image data file to be converted (specified by the user) stored in the external storage device 2008, and receives the first and second frames. Processing for storing in a hard disk or the like as a moving image file of a low-frequency subframe and a high-frequency subframe obtained by the same processing as in the embodiment is performed. Note that the double-speed output destination may be output to the display device instead of being saved as a file.

  In particular, when a moving image converted to double speed is saved as a file, real-time playback is not necessary. Therefore, the double speed moving image file may be created at a speed depending on the processing capability of the CPU 2002. Therefore, the timing adjustment steps in steps S307 and S309 in FIG. 3 or steps S608 and S610 in FIG. 6 are not necessary.

  As described above, the computer can perform the same processing as in the first and second embodiments according to the computer program.

  In general, the computer program is stored in a computer-readable storage medium such as a CD-ROM or a memory card. The computer-readable storage medium is set in a reading device (a CD-ROM drive or a memory card reader) included in the computer, and can be executed by copying or installing in the system. Therefore, it is obvious that a computer-readable storage medium storing such a computer program is also within the scope of the present invention.

1 is a block configuration diagram of an image processing apparatus according to a first embodiment. It is a figure which shows the waveform in each process step in 1st Embodiment. It is a flowchart which shows the flow of the process in 1st Embodiment. It is a block block diagram of the image processing apparatus of 2nd Embodiment. It is a figure which shows the waveform in each process step in 2nd Embodiment. It is a flowchart which shows the flow of the process in 2nd Embodiment. It is a figure explaining the light emission time of a hold type display device. It is a figure explaining the dynamic characteristic of a hold type display apparatus. It is a figure explaining the light emission time in the double speed drive of a hold type display device. It is a figure explaining the dynamic characteristic in the double speed drive of a hold type display apparatus. It is a figure explaining the light emission time of an impulse type display apparatus. It is a figure explaining the dynamic characteristic of an impulse type display apparatus. It is a figure explaining the light emission time in the double speed drive of an impulse type display apparatus. It is a figure explaining the dynamic characteristic in the double speed drive of an impulse type display apparatus. It is a figure explaining the conventional circuit structure. It is a figure explaining the processing waveform by a conventional method. It is a block diagram which shows the hardware structural example of a computer.

Claims (8)

An image processing apparatus that converts moving image data composed of F frames per unit time into moving image data composed of 2F subframes per unit time,
Input means for inputting moving image data in units of frames;
Low-pass filter means for low-pass filtering the frame input by the input means;
When the difference pixel value obtained by performing the process of subtracting each pixel value of the frame after filtering by the low-pass filter means from each pixel value of the frame input by the input means has a negative value A positive difference frame composed of difference pixel values of “0” or more, which is “0”, is generated, and if the difference pixel value has a positive value, a difference pixel of “0” or less which is “0” Difference calculating means for generating a negative difference frame composed of values;
A low-frequency subframe generating means for generating a low-frequency subframe by adding the negative difference frame to the filtered frame obtained by the low-pass filter means;
High-frequency subframe generation means for generating a high-frequency subframe by adding the positive difference frame to the frame input by the input means;
An image processing apparatus comprising: the low-frequency subframe; and an output unit that outputs the high-frequency subframe.   The image processing apparatus according to claim 1, wherein the output means outputs to a hold type display device. A control method of an image processing apparatus for converting moving image data composed of F frames per unit time into moving image data composed of 2F subframes per unit time,
An input process for inputting moving image data in units of frames;
A low-pass filter step of low-pass filtering the frame input by the input step;
When each pixel value of the frame after the filtering process by the low-pass filter process is subtracted from each pixel value of the frame input in the input process, and the difference pixel value obtained by subtraction has a negative value A positive difference frame composed of difference pixel values of “0” or more, which is “0”, is generated, and if the difference pixel value has a positive value, a difference pixel of “0” or less which is “0” A difference calculating step for generating a negative difference frame composed of values;
A low-frequency subframe generating step of generating a low-frequency subframe by adding the negative difference frame to the frame after the filtering process obtained in the low-pass filter step;
A high-frequency subframe generating step of generating a high-frequency subframe by adding the positive difference frame to the frame input in the input step;
An output process for outputting the low-frequency subframe and the high-frequency subframe. An image processing apparatus control method comprising: An image processing apparatus that converts moving image data composed of F frames per unit time into moving image data composed of 2F subframes per unit time,
Input means for inputting moving image data in units of frames;
Low-pass filter means for low-pass filtering the input frame;
When the difference pixel value obtained by performing the process of subtracting each pixel value of the frame after filtering by the low-pass filter means from each pixel value of the frame input by the input means has a positive value Difference calculation means for generating a negative difference frame composed of difference pixel values equal to or less than “0”, which is “0”;
Adding means for adding the negative difference frame to the frame after filtering obtained by the low-pass filter means;
Low-frequency subframe generation means for generating a low-frequency subframe by multiplying each pixel value in the frame obtained by the addition means by a preset multiplication coefficient less than 1,
High-frequency subframe generating means for generating a high-frequency subframe by subtracting the low-frequency subframe from the frame input by the input means;
An image processing apparatus comprising: the low-frequency subframe; and an output unit that outputs the high-frequency subframe.   The image processing apparatus according to claim 4, wherein the output means outputs to an impulse type display device. A control method of an image processing apparatus for converting moving image data composed of F frames per unit time into moving image data composed of 2F subframes per unit time,
An input process for inputting moving image data in units of frames;
A low-pass filter process for low-pass filtering the input frame;
When the difference pixel value obtained by subtracting each pixel value of the frame after the filter processing by the low-pass filter step from each pixel value of the frame input in the input step has a positive value A difference calculating step for generating a negative difference frame composed of difference pixel values equal to or less than “0”, which is “0”;
An addition step of adding the negative difference frame to the filtered frame obtained in the low-pass filter step;
A low-frequency subframe generation step of generating a low-frequency subframe by multiplying each pixel value in the frame obtained by the addition step by a preset multiplication coefficient less than 1;
A high-frequency subframe generating step for generating a high-frequency subframe by subtracting the low-frequency subframe from the frame input in the input step;
An output process for outputting the low-frequency subframe and the high-frequency subframe. An image processing apparatus control method comprising:   A computer program for causing a computer to function as the image processing apparatus according to claim 1 by being read and executed by a computer.   A computer-readable storage medium storing the computer program according to claim 7.

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