JP2007264661A - Hold type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of a display image by emphasizing edges while suppressing emphasis of noise components. <P>SOLUTION: The hold type image display device which displays an image while keeping the luminance of display light nearly constant for a period of one field includes an area detector 21 which detects a part having a change of more than predetermined area in the image to be displayed according to differences between frames, an adder 24, a multiplier 25, and an HPF 26 which emphasize edges of the part detected by the area detector 21 in the image to be displayed, and a display which displays the edge-emphasized image. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection-type display device (projector) that displays an image while maintaining the luminance of display light substantially constant for one field, a hold-type image display device such as an LCD, an organic EL, a plasma display, and an LED display. The present invention relates to a hold-type image display apparatus that performs edge enhancement of an image.

  A hold-type image display device that displays an image while maintaining the luminance of display light substantially constant for one field, such as a projection display device, an LCD, an organic EL, a plasma display, and an LED display, is described in the document “Video display on hold-type display”. “Image quality”, written by Yasushi Kurita (Technical Report Vol.23, No.40, P55-P60), perception of a phenomenon called “motion blur” during video display There is a problem. In the case of a liquid crystal projector, the video signal is generally rewritten at 60 frames / second (about 16.7 ms per screen), whereas the response of a TN mode liquid crystal widely used for liquid crystal projectors is several tens of times between halftones. Since it is in the order of ms, the switching response of the liquid crystal is slow, which also contributes to motion blur.

  Here, the motion blur is a reduction in which the spatial frequency of the image is visually reduced, and appears in a portion where there is motion in the image. As a conventional hold-type image display device that solves this motion blur, there is known a device that selectively performs high-frequency emphasis, that is, edge emphasis on a spatial frequency, on a portion in which an image has moved. In this hold-type image display device, two consecutive image frames are compared, and a portion that has changed is determined to be a portion that has moved, and edge enhancement is performed. This hold-type image display device has various input sources (input series) such as HDTV (high-definition television), analog TV and other video system (TV system) input, PC (personal computer) system input, etc. Input and display a resolution image.

  However, according to the above-described conventional hold-type image display device, the edge enhancement is performed by determining all the changed portions as the portions that have moved based on the difference between the image frames. The components are also emphasized at the same time, and there is a problem that the quality of the display image is lowered. In particular, when a digital image source subjected to digital compression, such as MPEG2, is handled, noise accompanying compression processing is included in the motion image, so that the influence of noise component enhancement becomes significant.

  Further, according to the above-described conventional hold-type image display device, there are various input sequences having different moving image ratios, compression / non-compression, etc., and the input image has various resolutions, but the edges are uniform. Since emphasis is performed, appropriate edge emphasis according to the input series and the resolution of the input image cannot be performed, and there is a problem that the quality of the display image is deteriorated.

  The present invention has been made in view of the above, and has as its first object to improve the quality of a display image by performing edge enhancement while suppressing enhancement of noise components. A second object of the present invention is to improve the quality of a display image by performing appropriate edge enhancement according to the input sequence and the resolution of the input image.

  In order to achieve the above object, a hold-type image display device according to claim 1 is a hold-type image display device that displays an image while maintaining the luminance of display light substantially constant for one field. Based on the above, area detection means for detecting a portion of the image to be displayed that has changed more than a predetermined area, and edge enhancement means for performing edge enhancement of the portion detected by the area detection means in the displayed image And image display means for displaying an image whose edge has been enhanced by the edge enhancement means.

  In the hold-type image display device according to claim 1, the area detection unit detects a portion of the displayed image that has changed by a predetermined area or more based on a difference between image frames, and performs edge enhancement. The means performs edge enhancement of the portion detected by the area detection means in the image to be displayed, and the image display means displays the image that has been edge enhanced by the edge enhancement means. As a result, the probability of performing edge enhancement on a portion that has moved while avoiding a noise portion is increased.

  A hold type image display device according to claim 2 is a hold type image display device that displays an image while maintaining the luminance of display light substantially constant for one field, and a difference for detecting an absolute value luminance difference between image frames. Based on the detection means and the detection result of the difference detection means, the own pixel has an absolute value luminance difference greater than or equal to a predetermined threshold value, and other pixels having an absolute value luminance difference greater than or equal to the predetermined threshold value are predetermined around the own pixel. A pixel detection unit that detects a predetermined number of pixels within a range, an edge enhancement unit that performs edge enhancement of pixels detected by the pixel detection unit among images to be displayed, and an image that has been edge enhanced by the edge enhancement unit And image display means for displaying.

  In the hold-type image display device according to claim 2, the difference detecting unit detects an absolute value luminance difference between the image frames, and the pixel detecting unit detects whether the own pixel is based on the detection result of the difference detecting unit. Edge enhancement means displays an absolute value luminance difference equal to or greater than a predetermined threshold value, and detects other pixels having an absolute value luminance difference equal to or greater than the predetermined threshold value within a predetermined range around the own pixel. Among the images, the edge of the pixel detected by the pixel detection unit is enhanced, and the image display unit displays the image whose edge is enhanced by the edge enhancement unit. As a result, the probability of performing edge enhancement on a portion that has moved while avoiding a noise portion is increased.

  According to a third aspect of the present invention, there is provided the hold-type image display device according to the second aspect, further comprising changing means for changing at least one of the predetermined threshold, the predetermined range, and the predetermined number. It has.

  In the hold-type image display device according to claim 3, the changing unit changes at least one of the predetermined threshold, the predetermined range, and the predetermined number, so that the user can appropriately adjust the edge enhancement. .

  According to a fourth aspect of the present invention, there is provided a hold-type image display device that detects an absolute value luminance difference between image frames in a hold-type image display device that displays an image while maintaining the luminance of display light substantially constant for one field. Based on a detection unit, a two-dimensional low-pass filter that removes high-frequency components in the two-dimensional space in which the absolute value luminance differences detected by the difference detection unit are arranged, and a removal result of the two-dimensional low-pass filter, a predetermined threshold value or more A pixel detection unit that detects pixels having an absolute value luminance difference, an edge enhancement unit that performs edge enhancement of pixels detected by the pixel detection unit, and an image that has been edge enhanced by the edge enhancement unit. Image display means for displaying.

  In the hold type image display device according to claim 4, the difference detecting means detects the absolute value luminance difference between the image frames, and the two-dimensional low-pass filter arranges the absolute value luminance differences detected by the difference detecting means. The high-frequency component in the two-dimensional space is removed, the pixel detecting unit detects a pixel having an absolute value luminance difference equal to or greater than a predetermined threshold based on the removal result of the two-dimensional low-pass filter, and the edge enhancing unit displays the image Among them, edge enhancement of pixels detected by the pixel detection means is performed, and the image display means displays an image whose edges are enhanced by the edge enhancement means. As a result, the probability of performing edge enhancement on a portion that has moved while avoiding a noise portion is increased.

  The hold type image display device according to claim 5 is a hold type image display device that displays an image while maintaining the luminance of display light substantially constant for one field, and a difference for detecting an absolute value luminance difference between image frames. A detection unit, a two-dimensional low-pass filter for removing high-frequency components in a two-dimensional space in which the absolute value luminance differences detected by the difference detection unit are arranged, and an edge for each pixel based on the removal result of the two-dimensional low-pass filter Gain determining means for determining an enhancement gain, edge enhancement means for performing edge enhancement based on the determination by the gain determination means, and image display means for displaying an image that has been edge enhanced by the edge enhancement means. Is.

  In the hold-type image display device according to claim 5, the difference detection unit detects the absolute value luminance difference between the image frames, and the two-dimensional low-pass filter arranges the absolute value luminance differences detected by the difference detection unit. The high-frequency component in the two-dimensional space is removed, the gain determination means determines the edge enhancement gain for each pixel based on the removal result of the two-dimensional low-pass filter, and the edge enhancement means is based on the determination by the gain determination means. Then, edge enhancement is performed, and the image display means displays the image that has been edge enhanced by the edge enhancement means. As a result, the probability of performing edge enhancement on a portion that has moved while avoiding a noise portion is increased.

  The hold type image display device according to claim 6 is the hold type image display device according to claim 2 or 3, further comprising edge enhancement for each pixel based on the number of other pixels within the predetermined range. Gain deciding means for deciding the gain is provided, and the edge enhancing means performs edge enhancement based on the determination by the gain deciding means.

  In the hold-type image display device according to claim 6, the gain determining means determines the edge enhancement gain for each pixel based on the number of other pixels within the predetermined range, and the edge enhancing means is the gain determining means. Edge enhancement is performed based on the determination by Thereby, more appropriate edge enhancement can be performed.

  The hold type image display device according to claim 7 is the hold type image display device according to any one of claims 1 to 4, further comprising an input sequence setting means for selecting and setting an image input sequence. And gain determining means for determining the gain of edge enhancement by the edge enhancement means based on the setting by the input series setting means.

  In the hold-type image display device according to claim 7, the input series setting means selects and sets the input series of the image, and the gain determination means uses the edge enhancement gain based on the setting by the input series setting means. To decide. Thereby, appropriate edge emphasis according to an input series can be performed.

  According to an eighth aspect of the present invention, there is provided a hold-type image display device according to any one of the first to fourth aspects, further comprising a resolution detection means for detecting a resolution of an input image, and the resolution. Gain determination means for determining a gain of edge enhancement by the edge enhancement means based on a detection result of the detection means.

  In the hold-type image display device according to the eighth aspect, the resolution detection means detects the resolution of the input image, and the gain determination means determines the edge enhancement gain based on the detection result of the resolution detection means. Thereby, appropriate edge enhancement according to the resolution of the input image can be performed.

  A hold-type image display device according to claim 9 is an image to be displayed based on a difference between image frames in a hold-type image display device that displays an image while maintaining the luminance of display light substantially constant for one field. A motion detection unit that detects a portion of the image to be moved, an edge enhancement unit that performs edge enhancement of the portion detected by the motion detection unit in the displayed image, and an input sequence of the image. Input series setting means; gain determining means for determining gain of edge enhancement by the edge enhancement means based on settings by the input series setting means; and image display means for displaying an image edge-enhanced by the edge enhancement means Are provided.

  In the hold-type image display device according to claim 9, the input series setting means selects and sets the input series of the image, and the gain determination means uses the edge enhancement based on the setting by the input series setting means. The edge enhancement gain is determined by the means, the motion detection means detects a portion of the image to be moved based on the difference between the image frames, and the edge enhancement means determines the motion of the image to be displayed. Edge detection is performed on the portion detected by the detection means, and the image display means displays an image edge-enhanced by the edge enhancement means. Thereby, appropriate edge emphasis according to an input series can be performed.

  The hold-type image display device according to claim 10 is an image to be displayed based on a difference between image frames in the hold-type image display device that displays an image while maintaining the luminance of display light substantially constant for one field. A motion detection unit that detects a portion of the image to be moved, an edge enhancement unit that performs edge enhancement of a portion of the displayed image detected by the motion detection unit, and a resolution detection unit that detects a resolution of the input image And gain determining means for determining the gain of edge enhancement by the edge enhancement means based on the detection result of the resolution detection means, and image display means for displaying an image edge-enhanced by the edge enhancement means. Is.

  In the hold-type image display device according to claim 10, the resolution detection means detects the resolution of the input image, and the gain determination means uses the edge enhancement gain by the edge enhancement means based on the detection result of the resolution detection means. And the motion detection means detects a portion of the image to be moved based on the difference between the image frames, and the edge enhancement means detects the portion of the image to be detected detected by the motion detection means. And the image display means displays the image whose edge is emphasized by the edge enhancement means. Thereby, appropriate edge enhancement according to the resolution of the input image can be performed.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments.
In the following embodiments, a display device including a display unit (pixel) as shown in the following (1) or (2) is referred to as a “hold-type image display device”. (1) Each display unit (pixel) holds each image signal (luminance signal) for one field (or one frame) period and emits light based on the held image signal (luminance signal), or Modulate. (2) One display unit (pixel) continues to emit or modulate light based on the same image signal (luminance signal) for at least one field (or one frame) period.

(Embodiment 1)
In Embodiment 1 of the present invention, based on the difference between two consecutive image frames, a portion of the displayed image that has changed by a predetermined area or more is detected, edge enhancement is performed on that portion, and An example of a liquid crystal projector that determines the edge enhancement gain α according to the input sequence and resolution of an image will be described. FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal projector according to Embodiment 1 of the present invention.

The liquid crystal projector according to the first embodiment includes a video signal conversion circuit 2, a liquid crystal display drive circuit 6, a liquid crystal display panel 9, a frame memory 1, a remote control unit 4, a CPU 5, an illumination optical system 10, and a projection. And an optical system 8.
The video signal conversion circuit 2, the remote controller 4, the CPU 5 and the liquid crystal display driving circuit 6 are connected to the bus 11. The liquid crystal display panel 9 is illuminated almost uniformly by the illumination optical system 10, and an image displayed on the liquid crystal display panel 9 is projected on the projection screen 7 by the projection optical system 8. In FIG. 1, the illumination optical system 10 and the projection optical system 8 are simplified.

  The video signal conversion circuit 2 AD-converts the input analog image signal AV1, writes the AD-converted image data into the frame memory 1, reads out the image data from the frame memory 1, and performs edge enhancement of the image. The edge-enhanced image data DV2 is output. As the analog image signal AV1, for example, an image signal such as a computer screen display RGB signal output from a personal computer (PC), or a moving image display composite image signal output from a video recorder or television (TV) is used. Supplied.

  The image data DV2 output from the video signal conversion circuit 2 is supplied to the liquid crystal display panel drive circuit 6. The liquid crystal display panel drive circuit 6 displays an image on the liquid crystal display panel 9 in accordance with the supplied image data DV2. The image displayed on the liquid crystal display panel 9 is projected on the projection screen 7 using the projection optical system 8 and the illumination optical system 10. That is, light incident on the liquid crystal display panel 9 by the illumination optical system 10 is modulated according to image data given to the liquid crystal display panel 9, and light emitted from the liquid crystal display panel 9 is projected onto the projection screen 7 by the projection optical system 8. Projected.

  The remote control control unit 4 performs various controls based on commands from the remote control 3 operated by the user. Examples of the control performed by the remote control unit 4 include control of parameters related to edge enhancement processing described later. The CPU 5 controls each part of the liquid crystal projector. The control performed by the CPU 5 includes, for example, input system switching control such as a PC system, an HDTV system, and an NTSC system. The CPU 5 selects an input sequence used for display, and outputs input sequence information for notifying the selected input sequence to the video signal conversion circuit 2. For example, the CPU 5 may select an input series based on a signal output from the remote control unit 4 in response to an operation of the remote control 3, or based on a detection result of a detection unit (not shown) that performs connector insertion detection. An input sequence may be selected.

  FIG. 2 is a block diagram showing a schematic configuration of the video signal conversion circuit 2 shown in FIG. The video signal conversion circuit 2 includes synchronization separation units 12 and 13, an AD conversion unit 14, a resolution detection unit 15, and a video processor 17. The sync separator 12 separates the HDTV composite image signal Sig1 into a sync signal SYNC1 and a component image signal (analog image signal not including a sync signal) and outputs the signal. The sync separator 13 separates the NTSC composite image signal Sig2 into a sync signal SYNC2 and a component image signal, and outputs them. These component image signals are composed of three color signals representing three color RGB images.

  For the PC RGB signal Sig3, since the synchronization signal SYNC3 is separately input, it is not necessary to use a synchronization separation unit. The AD conversion unit 14 receives the RGB signal Sig3 and the component image signal output from the synchronization separation units 12 and 13, and converts the color signal into image data DV1 by a plurality of AD converters (not shown) in the AD conversion unit 14. Convert. Note that the timing of AD conversion by the plurality of AD converters is controlled by a dot clock DCLK generated inside the video processor 17 based on the synchronization signals SYNC1 to SYNC3.

  The resolution detection unit 15 receives the synchronization signals SYNC1 to SYNC3 of each series, and detects the resolution of the input image based on the input synchronization signals SYNC1 to SYNC3. Then, the resolution detection unit 15 outputs the synchronization signals SYNC1 to SYNC3 and resolution information I1 indicating the resolution of the input image to the video processor 17. The video processor 17 receives the image data DV1 from the AD converter 14 and performs control for writing and reading image data to and from the frame memory 1. The video processor 17 receives the resolution information I1 from the resolution detection unit 15, the input sequence information I2 from the CPU 5, and the control signal from the remote control unit 4, and performs input sequence switching and edge enhancement processing.

  FIG. 3 is a block diagram showing a schematic configuration of the video processor 17 shown in FIG. The video processor 17 includes a first processing unit 18 and a second processing unit 19. The first processing unit 18 receives the image data DV1, performs writing control and reading control of the image data to the frame memory 1, and outputs the image data DV3. The second processing unit 19 receives the image data DV3, and also inputs resolution information I1 from the resolution detection unit 15, input sequence information I2 from the CPU 5, and a control signal from the remote control control unit 4 to switch the input sequence. And edge enhancement processing.

  FIG. 4 is a block diagram illustrating a schematic configuration of the second processing unit 19 illustrated in FIG. 3. The second processing unit 19 includes an input sequence switching unit 20, an area detection unit 21, a delay unit 22, a gain determination unit 23, an adder 24, a multiplier 25, and a high-pass filter (HPF) 26. I have. The input sequence switching unit 20 receives the image data DV3 from the first processing unit 18, and according to the input sequence information I2, any input sequence (PC system, HDTV system, or NTSC system) included in the image data DV3. Select and output the image data.

  The input switching control unit 14a may be provided in the AD conversion unit 14, or may be provided in the input portion of the video signal conversion circuit 2, that is, in the video signal conversion circuit 2, and the synchronization separation unit 12 and the synchronization separation unit. 13 may be provided in the previous stage of each of the AD converter 14 and the resolution detector 15. When the input switching control unit is provided in the input portion of the video signal conversion circuit 2, the sync separation unit can be shared between the HDTV system and the NTSC system. That is, only one sync separator common to the HDTV system and the NTSC system may be provided. The area detection unit 21 receives the image data from the input sequence switching unit 20 and the previous image data from the frame memory 1 and displays them based on the difference between these image data (image frames). A portion of the image that has changed by a predetermined area or more is detected as a moving portion of the image (a portion that has moved).

  A portion that has changed less than a predetermined area is determined to be noise. Note that the area detection unit 21 may detect all portions where the absolute value luminance difference between image frames is equal to or greater than a predetermined threshold regardless of the area as a moving portion. The gain determination unit 23 has an LUT (Look Up Table), which will be described later, in which the edge enhancement gain is associated with the input sequence and resolution of the image, and the edge enhancement gain for the portion detected by the area detection unit 21 is determined as the resolution. It decides according to information I1 and input series information I2. The gains other than those detected by the area detection unit 21 are “0”. Further, the gain determination unit 23 may change the filter characteristics of the HPF 26 according to the resolution information I1 and the input sequence information I2.

  The HPF 26 receives the image data from the input sequence switching unit 20 and passes the high-frequency part, that is, the edge part of the image. The multiplier 25 multiplies the edge portion of the image that has passed through the HPF by the gain determined by the gain determination unit 23. Thereby, data of the edge emphasis portion is generated. The adder 24 adds the data from the multiplier to the image data from the delay unit 22. As a result, image data DV2 with edge enhancement is generated. The delay unit 22 delays the image data from the input sequence switching unit 20 and outputs the delayed image data to the adder 24 to adjust the timing of addition by the adder 24.

FIG. 5 is a block diagram illustrating a schematic configuration of the area detection unit 21 illustrated in FIG. 4. The area detection unit 21 includes an absolute value luminance difference calculation unit 27, a binarization unit 28, and a pixel detection unit 29. The absolute value luminance difference calculation unit 27 receives the image data from the input sequence switching unit 20 and the previous image data from the frame memory 1 and calculates the absolute value luminance difference between these image frames. That is, the absolute value of the luminance difference between successive image data is calculated. The binarization unit 28 inputs the absolute value luminance difference calculated by the absolute value luminance difference calculation unit 27 and binarizes it using a predetermined threshold value.
That is, it is determined that the portion above the predetermined threshold is a portion where the image has changed and is set to a value “1”, and the portion below the predetermined threshold is determined to be a portion where the image has not changed and the value “ 0 ”.

Further, the binarization unit 28 changes the threshold value based on the control signal from the remote controller control unit 4. The user can set a desired threshold value by operating the remote controller 3.
The pixel detection unit 29 receives the binarized data from the binarization unit 28 and is a pixel having a value “1”, and a pixel having a value “1” within a predetermined range around the pixel is predetermined. Detect more than the number of pixels. In addition, the pixel detection unit 29 changes the predetermined range and the predetermined number based on a control signal from the remote controller control unit 4. The user can set a desired predetermined range and a predetermined number by operating the remote controller 3.

  FIG. 6 is a block diagram of a schematic configuration of a pixel counting circuit included in the pixel detection unit 29 according to the first embodiment. The pixel counting circuit included in the pixel detection unit 29 includes four pixel delay elements 31 to 34, five-input adders 39 and 40, and four line delay elements (line memories) 35 to 38. The four pixel delay elements 31 to 34 and the five-input adder 39 perform an addition operation for five pixels in the horizontal direction of the binary pixel image from the binarization unit 28. The four line delay elements 35 to 38 and the 5-input adder 40 add 5 lines in the horizontal direction of the binary pixel image.

  As a result, the number of pixels having the value “1” in the 5 × 5 range of the binary pixel image can be counted. Further, by adopting such a hardware configuration, memory access can be performed in parallel, and real-time processing becomes possible. Further, the pixel delay elements 31 to 34 and the line delay elements 35 to 38 are turned on / off in accordance with a control signal from the remote control unit 4. Thereby, the range which counts pixels, such as 3x3, can be changed. In this example, the example of counting the number of pixels within a maximum range of 5 × 5 is given, but the number of pixels within a range of 5 × 5 or more can be counted by increasing the number of pixel delay elements and line delay elements. It may be.

  FIG. 7 is a block diagram showing a schematic configuration of the HPF 26 shown in FIG. The HPF 26 is, for example, a programmable two-dimensional HPF circuit having a maximum of 5 taps × 5 taps. The HPF 26 includes four pixel delay elements 41 to 44, multipliers 45 to 49 and 55 to 59 (coefficients kh0 to kh4 and kv0 to kv4), five input adders 50 and 60, and four line delay elements 51. -54. Multipliers 45 to 49 and 55 to 59 change coefficients kh0 to kh4 and kv0 to kv4 according to the control signal from gain determination unit 23.

  These coefficients are given as digital information by an LUT described later of the gain determination unit 23. By changing the coefficients kh0 to kh4 and kv0 to kv4 of the multipliers 45 to 49 and 55 to 59, the characteristics of the HPF 26 and the number of taps can be changed. For example, by setting the coefficients kh0 to kh4 and kv0 to kv4 of the multipliers 45 to 49 and 55 to 59 as shown in Expression (1), a 3-tap × 3-tap two-dimensional HPF can be obtained.

kh0 = 0, kh1 = −0.5, kh2 = 1, kh3 = −0.5, kh4 = 0, kv0 = 0, kv1 = −0.5, kv2 = 1, kv3 = −0.5, kv4 = 0 Formula (1)
Further, by adopting such a hardware configuration, memory access can be performed in parallel, and real-time processing becomes possible. In this example, a programmable two-dimensional HPF circuit having a maximum of 5 taps × 5 taps is taken as an example, but an HPF having 5 taps × 5 taps or more is configured by increasing the number of pixel delay elements, multipliers, and line delay elements. You can also

  FIG. 8 is a chart of an example of the LUT of the gain determination unit 23 according to the first embodiment. The LUT of the gain determination unit 23 includes input series such as PC system, digital TV (HDTV) system, analog TV (NTSC) system, VGA (640 × 480), XGA (1024 × 768), SXGA (1280 × 1024), The coefficients kh0 to kh4 and kv0 to kv4 of HPF26 and edge enhancement are adapted to the resolution of 480i (720 × 480), 720p (1280 × 720), 1080i (1920 × 1080), NTSC (768 × 485, etc.), etc. Gain α is specified. Here, the relationship between the image input sequence and the gain α will be described.

  When a TV system such as a digital TV system or an analog TV system is compared with a PC system, the TV system often handles moving images, so the gain α is increased to increase the motion blur improvement effect. On the other hand, since the PC system often handles still images, the gain α is lowered to suppress adverse effects such as noise increase. Further, when the digital TV system and the analog TV system are compared with almost the same resolution, the digital TV system subjected to digital compression such as MPEG2 has a lower gain than the analog system that does not perform digital compression. This is for suppressing noise components such as block distortion caused by digital compression from being emphasized by high frequency emphasis. A general analog system is NTSC, but high-resolution baseband analog video used for dedicated use such as business use may be included.

  Next, the relationship between the resolution of the input image, the gain α, and the characteristics of the HPF 26 will be described. When the resolution of the input image and the display resolution (the resolution of the liquid crystal display panel 9) match or approximate, that is, when the difference between these resolutions is within a predetermined value, the difference between these resolutions is greater than or equal to the predetermined value. As compared with this case, the peak frequency of the HPF 26 is increased and the gain α is increased. This is because, unlike the case where the difference between these resolutions is greater than or equal to a predetermined value, there is no image degradation component due to scaling (resolution conversion), and therefore there are few adverse effects due to high frequency emphasis.

  On the other hand, when the resolution of the input image is larger than the display resolution by a predetermined value or more, the gain α is lowered and the peak frequency of the HPF is lowered compared to the case where these resolutions match or approximate. This is to suppress the emphasis by high-frequency emphasis on interference caused by resolution conversion such as aliasing distortion. Further, when the resolution of the input image is smaller than the display resolution by a predetermined value or more, the gain α is lowered and the peak frequency of the HPF is lowered as compared with the case where these resolutions match or approximate. This is to prevent the interference due to the resolution conversion such as the jaggedness of the image contour portion from being emphasized by the high frequency emphasis.

  Here, the display resolution is set to 1280 × 720. The entity of the LUT is a ROM. The horizontal and vertical characteristics of the HPF 26 change as shown in FIGS. 9 to 11 according to the resolution of the image and the input system indicated by the resolution information I1 and the input series information I2. After the processing of the HPF 26 by this characteristic, the data passed through the HPF 26 is further multiplied by a gain α by the multiplier 25.

  The area detection unit 21 corresponds to the motion detection unit and the area detection unit of the present invention, the absolute value luminance difference calculation unit 27 corresponds to the difference detection unit of the present invention, and the remote control unit 4 corresponds to the present invention. Corresponding to the changing means, the CPU 5 corresponds to the input series setting means of the present invention, the adder 24, the multiplier 25 and the HPF 26 correspond to the edge emphasizing means of the present invention, the liquid crystal display driving circuit 6, the projection optical system. 8, the liquid crystal display panel 9 and the illumination optical system 10 correspond to the image display means of this invention.

  With the above configuration, the operation of the first embodiment will be described with reference to the drawings. FIG. 12 is an explanatory diagram for explaining the operation of the absolute value luminance difference detection unit 27 according to the first embodiment. For example, as shown in FIG. 12A, an arbitrary image frame Pa includes a figure 61 and noises N1 to N3, and as shown in FIG. 12B, the next image frame Pa. Suppose that the image frame P- (a + 1) includes the figure 62 and noises N4 to N6. The figure 62 is obtained by moving the figure 61 to the right. The absolute value luminance difference detection unit 27 calculates the absolute value of the difference between the luminance of each pixel in the image frame P-1 and the luminance of each pixel in the image frame P- (a + 1).

  As shown in FIG. 12C, the calculation result of the absolute value luminance difference detection unit 27 includes binary pixel images N11 to N16 based on noises N1 to N3 and N4 to N6 together with the binary pixel images 63 based on the figures 61 and 62. Including. The binary pixel images N11 to N16 are noise portions and portions that should not be edge-enhanced. Here, the binary pixel image 63 that should be edge-enhanced that is a moving part exists in a cluster and has a large area, while the binary pixel images N11 to N16 that should not be edge-enhanced that are noise parts are scattered. And a small area. The pixel detection unit 29 excludes the binary pixel images N11 to N16 from the edge enhancement target using this area difference.

FIG. 13 is an explanatory diagram for explaining the operation of the pixel detection unit 29 according to the first embodiment. The pixel detection unit 29 counts the pixels having the value “1” in the predetermined range while sweeping the predetermined range in the two-dimensional space in which the absolute value luminance difference values detected by the absolute value luminance difference detection unit 27 are arranged. Go sequentially. The pixels of the binary pixel images N11 to N16 have a small number of pixels having a value “1” within a predetermined range around them (see A1 in FIG. 13).
On the other hand, the pixels of the binary pixel image 63 have a large number of pixels having a value “1” within a predetermined range around the pixels (see A2 in FIG. 13). For example, if a certain pixel has a value “1” and the number of pixels having a value “1” within the surrounding 5 × 5 range is 13 or more, the pixel is included in the binary pixel image 63. Judge.

  FIG. 14 is a flowchart of a process procedure performed by the pixel detection unit 29 according to the first embodiment. When there is a pixel having a value “1”, the pixel detection unit 29 first counts the number of pixels within a predetermined range around the pixel (S1), and determines whether or not it is equal to or greater than a predetermined threshold (S2). If it is less than the predetermined threshold, it is determined that it is a noise part (S4), and if it is equal to or greater than the predetermined threshold, it is determined that it is a moving part of the image and notified to the gain determination unit 23 (S3). The gain determination unit 23 determines the gain α of the pixel determined by the area detection unit 29 as a moving part of the image. The gains of the pixels in the noise part and other parts are “0”.

  As described above, according to the first embodiment, the area detection unit 21 detects a portion of the image to be displayed that has changed by a predetermined area or more based on the difference between the image frames, and the addition unit 24. , The multiplication unit 25 and the HPF 26 perform edge enhancement of the portion detected by the area detection unit 21 in the displayed image, and the liquid crystal display driving circuit 6, the projection optical system 8, the liquid crystal display panel 9, and the illumination optical system 10 are Display an edge-enhanced image. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

(Embodiment 2)
In the second embodiment of the present invention, instead of the second processing unit 19 in the first embodiment, a pixel having a value obtained by binarizing the absolute value luminance difference is “1” (hereinafter, simply a pixel having a value “1”). The second processing unit is provided that determines the gain α based on the number of pixels of the value “1” existing within a predetermined range around the pixel. FIG. 15 is a block diagram showing a schematic configuration of the second processing unit 71 according to the second embodiment of the present invention. Note that portions having the same configurations as those of the first embodiment are denoted by the same reference numerals as those in FIG.

  The second processing unit 71 of the second embodiment replaces the area detection unit 21 in the second processing unit 19 of the first embodiment with the value “1” existing within a predetermined range around the pixel of the value “1”. The area determination unit 72 that notifies the gain determination unit 73 of the number of pixels of “” is determined, and instead of the gain determination unit 23, the gain determination that determines the gain α of each pixel according to the number of pixels notified from the area detection unit 72 A portion 73 is provided. The area detection unit 72 has the same configuration as the area detection unit 21 of the first embodiment and operates in the same manner, but the number of pixels having the value “1” existing within a predetermined range around the pixel having the value “1”. To the gain determination unit 73.

  The gain determination unit 73 has the same configuration as the gain determination unit 23 of the first embodiment and operates in the same manner, but determines the gain α of each pixel according to the number of pixels notified from the area detection unit 72. FIG. 16 is a table of an example of the LUT of the gain determination unit 73 according to the second embodiment. The LUT of the gain determining unit 73 does not associate the input sequence and resolution of the image with the gain α, but the number of pixels of the value “1” existing in a predetermined range around the pixel of the value “1” and the pixels Is associated with the gain α.

  For example, when the number of pixels is 0-9, the gain α = 0, when the number of pixels is 10-14, the gain α = 0.5, and when the number of pixels is 10-24, the gain α = 0.7, and when the number of pixels is 25, the gain α = 1. Alternatively, the input series and resolution of the image, the number of pixels, and the gain α may be associated with each other. As a result, the multiplier 25 gives the pixel a gain α corresponding to the number of pixels of the value “1” existing within a predetermined range around the pixel of the value “1”. Other configurations and operations are the same as those in the first embodiment.

  As described above, according to the second embodiment, the gain determination unit 73 determines the edge enhancement gain α for each pixel based on the number of other pixels within the predetermined range, and the addition unit 24, the multiplication unit 25, and The HPF 26 performs edge enhancement based on the determination by the gain determination unit 73. Thereby, more appropriate edge enhancement can be performed.

(Embodiment 3)
In the third embodiment of the present invention, the moving portion of the image is detected by removing the high-frequency component in the two-dimensional space in which the area detection unit arranges the absolute value luminance differences in the first embodiment. FIG. 17 is a block diagram showing a schematic configuration of the second processing unit 81 according to the third embodiment of the present invention. Note that portions having the same configurations as those of the first embodiment are denoted by the same reference numerals as those in FIG. The second processing unit 81 according to the third embodiment removes high-frequency components in a two-dimensional space in which absolute value luminance differences are arranged instead of the area detection unit 21 in the second processing unit 19 according to the first embodiment. An area detecting unit 82 for detecting a moving part of the image is provided.

  FIG. 18 is a block diagram of a schematic configuration of the area detection unit 82 according to the third embodiment. Note that portions having the same configurations as those of the first embodiment are denoted by the same reference numerals as those in FIG. The area detection unit 82 includes a two-dimensional low-pass filter (two-dimensional LPF) 84 and a binarization unit 85 in place of the binarization unit 28 and the pixel detection unit 29 in the area detection unit 82 of the first embodiment. Is. The two-dimensional LPF 84 receives the absolute value luminance difference calculated by the absolute value luminance difference calculation unit 27, and removes high-frequency components in the two-dimensional space in which the absolute value luminance differences are arranged.

  Thereby, the noise part which is a high frequency component with a small area is removed, and a moving part with a large area remains. Further, the two-dimensional LPF 84 changes the characteristics based on a control signal from the remote controller control unit 4. The user can set a desired LPF characteristic by operating the remote controller 3. The binarization unit 85 inputs data that has passed through the two-dimensional LPF 84 and binarizes it using a predetermined threshold value. That is, it is determined that the portion above the predetermined threshold is a portion where the image has changed and is set to a value “1”, and the portion below the predetermined threshold is determined to be a portion where the image has not changed and the value “ 0 ”.

Further, the binarization unit 85 changes the threshold based on the control signal from the remote control unit 4. The user can set a desired threshold value by operating the remote controller 3.
Further, since the moving part of the image is also cut to some extent by the two-dimensional LPF 84, the binarization unit 85 also sets the part obtained by expanding the part of the value “1” by a predetermined amount so as to compensate for this. Good. The binarization unit 85 corresponds to the pixel detection means of this invention. Other configurations and operations are the same as those in the first embodiment.

  As described above, according to the third embodiment, the absolute value luminance difference calculation unit 27 detects the absolute value luminance difference between image frames, and the two-dimensional LPF 84 detects the absolute value detected by the absolute value luminance difference calculation unit 27. A high-frequency component in a two-dimensional space in which luminance differences are arranged is removed, and a binarization unit 85 detects pixels having an absolute luminance difference equal to or greater than a predetermined threshold based on the removal result of the two-dimensional low-pass filter, and an adder 24, the multiplier 25 and the HPF 26 perform edge enhancement of the pixels detected by the binarization unit 85 in the displayed image, and the liquid crystal display driving circuit 6, the projection optical system 8, the liquid crystal display panel 9, and the illumination optical system 10 Displays an edge-enhanced image. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

(Embodiment 4)
In the fourth embodiment of the present invention, in the third embodiment, the area detection unit does not perform binarization, and the absolute value luminance difference that has passed through the two-dimensional LPF 84 is directly output to the gain determination unit. The gain α corresponding to the absolute value luminance difference is determined. FIG. 19 is a block diagram showing a schematic configuration of the second processing unit according to the fourth embodiment of the present invention. Note that portions having the same configurations as those of the third embodiment are denoted by the same reference numerals as those in FIG.

  The second processing unit 91 according to the fourth embodiment outputs the absolute value luminance difference passed through the two-dimensional LPF 84 to the gain determination unit 93 as it is instead of the area detection unit 82 in the second processing unit 81 according to the third embodiment. And an area determining unit 92 for determining the gain α according to the absolute value luminance difference from the area detecting unit 92. FIG. 20 is a block diagram of a schematic configuration of the area detection unit 92 according to the fourth embodiment. In addition, the same code | symbol as FIG. 18 is attached | subjected about the part of the same structure as Embodiment 3. FIG.

The area detection unit 92 according to the fourth embodiment omits the binarization unit 85 from the area detection unit 82 according to the third embodiment, and outputs the absolute value luminance difference passed through the two-dimensional LPF 84 to the gain determination unit 93 as it is. It is a thing. FIG. 21 is a chart illustrating an example of an LUT of the gain determination unit 93 according to the fourth embodiment. The gain determination unit 93 has an LUT that associates the absolute value luminance difference with the gain α as shown in FIG. 21, and sets the gain α for each pixel in accordance with the absolute value luminance difference from the area detection unit 92. decide.
Other configurations and operations are the same as those in the third embodiment.

  As described above, according to the fourth embodiment, the absolute value luminance difference calculation unit 27 detects the absolute value luminance difference between image frames, and the two-dimensional LPF 84 detects the absolute value luminance difference calculation unit 27. The high-frequency component in the two-dimensional space in which the value luminance differences are arranged is removed, and the gain determination unit 93 determines the edge enhancement gain for each pixel based on the removal result of the two-dimensional LPF 84, and the adder 24 and multiplier 25. The HPF 26 performs edge enhancement based on the determination by the gain determination unit 93, and the liquid crystal display driving circuit 6, the projection optical system 8, the liquid crystal display panel 9, and the illumination optical system 10 display an edge-enhanced image. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

  Note that the functions of the video signal conversion circuit and the remote control unit according to the first to fourth embodiments may be realized by hardware or by a computer program. A computer program for realizing the functions of these units is provided in a form recorded on a computer-readable recording medium such as a floppy disk or a CD-ROM. The computer (liquid crystal projector) reads the computer program from the recording medium and transfers it to the internal storage device or the external storage device. Or you may make it supply a computer program to a computer via a communication path from a program supply apparatus.

  When realizing the functions of a computer, a computer program stored in an internal storage device is executed by the microprocessor of the computer. The computer program recorded on the recording medium may be directly executed by the computer. In this specification, a computer is a concept including a hardware device and an operating system (OS), and means a hardware device that operates under the control of the OS. Further, when an OS is not required and a hardware device is operated by a single application program, the hardware device itself corresponds to a computer.

  The hardware device includes a microprocessor such as a CPU and means for reading a computer program recorded on a recording medium. The computer program includes program code for causing such a computer to realize the functions described above. Some of the above functions may be realized by the OS instead of the application program. The “recording medium” in the present invention includes a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a printed matter on which a code such as a punch card or a bar code is printed, an internal storage device of a computer (RAM or ROM Etc.) and various media that can be read by a computer, such as an external storage device.

  In the first to fourth embodiments, the transmissive liquid crystal projector is taken as an example. However, the configurations of the first to fourth embodiments are applied to the transmissive projector and the reflective projector. be able to. Here, “transmission type” means that a light valve such as a liquid crystal light valve transmits light, and “reflection type” means that the light valve reflects light. Means. The light valve of the reflection type projector may be a liquid crystal light valve or a light valve using a micromirror.

  The projector includes a front projector that projects an image from the direction of observing the projection surface and a rear projector that projects an image from the opposite side to the direction of observing the projection surface. The configuration of 4 can be applied to any projector. Furthermore, the configurations of the first to fourth embodiments can be applied to other hold-type image display devices such as a hold-type image display device such as an LCD, an organic EL, a plasma display, and an LED display.

  As described above, the hold-type image display device according to the present invention (Claim 1) is a portion in which the area detection means has changed more than a predetermined area in the image displayed based on the difference between the image frames. The edge enhancement unit performs edge enhancement of the portion detected by the area detection unit in the image to be displayed, and the image display unit displays the image whose edge is enhanced by the edge enhancement unit. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

  In the hold-type image display device according to the present invention (Claim 2), the difference detecting means detects an absolute value luminance difference between image frames, and the pixel detecting means is based on the detection result of the difference detecting means. The pixel has an absolute value luminance difference greater than or equal to a predetermined threshold, and other pixels having an absolute value luminance difference greater than or equal to the predetermined threshold detect a pixel having a predetermined number or more within a predetermined range around the own pixel, Among the images to be displayed, edge enhancement of pixels detected by the pixel detection unit is performed, and the image display unit displays an image that has been edge enhanced by the edge enhancement unit. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

  In the hold-type image display device according to the present invention (claim 3), the changing means changes at least one of the predetermined threshold value, the predetermined range, and the predetermined number so that the user appropriately adjusts the edge enhancement. Therefore, the quality of the display image can be improved according to the user's preference.

  In the hold-type image display device according to the present invention (Claim 4), the difference detection unit detects an absolute value luminance difference between image frames, and the two-dimensional low-pass filter detects the absolute value luminance difference detected by the difference detection unit. The high-frequency components in the two-dimensional space in which the pixels are arranged are removed, the pixel detection means detects pixels having an absolute value luminance difference equal to or greater than a predetermined threshold based on the removal result of the two-dimensional low-pass filter, and the edge enhancement means displays Among the images to be processed, edge enhancement of the pixels detected by the pixel detection unit is performed, and the image display unit displays the image enhanced by the edge enhancement unit. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

  In the hold-type image display device according to the present invention (Claim 5), the difference detection unit detects an absolute value luminance difference between image frames, and the two-dimensional low-pass filter detects the absolute value luminance difference detected by the difference detection unit. The high-frequency components in the two-dimensional space in which the two are arranged are removed, the gain determining means determines the edge enhancement gain for each pixel based on the removal result of the two-dimensional low-pass filter, and the edge enhancing means is determined by the gain determining means Then, edge enhancement is performed based on the image, and the image display means displays the image edge-enhanced by the edge enhancement means. As a result, the probability of performing edge enhancement of a portion that has moved while avoiding the noise portion is increased, so that edge enhancement can be performed while suppressing enhancement of the noise component, and the quality of the display image can be improved.

  In the hold-type image display device according to the present invention (Claim 6), the gain determination means determines the edge enhancement gain for each pixel based on the number of other pixels within the predetermined range, and the edge enhancement means Since edge enhancement is performed based on the determination by the determination unit, more appropriate edge enhancement can be performed.

  In the hold-type image display device according to the present invention (Claim 7), the input series setting means selects and sets the input series of the image, and the gain determination means uses the edge enhancement based on the setting by the input series setting means. Determine the gain. Thereby, since appropriate edge emphasis according to an input series can be performed, the quality of a display image can be improved.

  In the hold-type image display device according to the present invention (Claim 8), the resolution detection means detects the resolution of the input image, and the gain determination means determines the edge enhancement gain based on the detection result of the resolution detection means. To do. Thereby, appropriate edge enhancement according to the resolution of the input image can be performed, so that the quality of the display image can be improved.

  In the hold-type image display device according to the present invention (invention 9), the input series setting means selects and sets an image input series, and the gain determination means uses the input series setting means based on the setting. The edge enhancement means determines the gain of edge enhancement, the motion detection means detects a portion of the image to be moved based on the difference between the image frames, and the edge enhancement means includes the image to be displayed. Then, edge enhancement of the portion detected by the motion detection means is performed, and the image display means displays an image whose edge is enhanced by the edge enhancement means. Thereby, since appropriate edge emphasis according to an input series can be performed, the quality of a display image can be improved.

  In the hold-type image display device according to the present invention (claim 10), the resolution detection means detects the resolution of the input image, and the gain determination means uses the edge enhancement means based on the edge enhancement based on the detection result of the resolution detection means. The motion detection means detects a portion of the image to be moved based on the difference between the image frames, and the edge enhancement means detects the motion detection means from the image to be displayed. Edge enhancement is performed on the selected portion, and the image display means displays the image that has been edge enhanced by the edge enhancement means. Thereby, appropriate edge enhancement according to the resolution of the input image can be performed, so that the quality of the display image can be improved.

1 is a block diagram showing a schematic configuration of a liquid crystal projector according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of a video signal conversion circuit illustrated in FIG. 1. FIG. 3 is a block diagram illustrating a schematic configuration of a video processor illustrated in FIG. 2. It is a block diagram which shows schematic structure of the 2nd process part shown in FIG. It is a block diagram which shows schematic structure of the area detection part shown in FIG. FIG. 3 is a block diagram illustrating a schematic configuration of a pixel counting circuit included in the pixel detection unit according to the first embodiment. It is a block diagram which shows schematic structure of HPF shown in FIG. 3 is a chart showing an example of an LUT of a gain determination unit according to the first exemplary embodiment; FIG. 3 is a diagram illustrating an example of frequency-gain characteristics of the LPF according to the first embodiment. FIG. 6 is a diagram illustrating another example of the frequency-gain characteristics of the LPF according to the first embodiment. FIG. 10 is a diagram illustrating still another example of the frequency-gain characteristics of the LPF according to the first embodiment. (A), (b) and (c) are explanatory drawings explaining operation | movement of the absolute value brightness | luminance difference detection part concerning Embodiment 1. FIG. FIG. 6 is an explanatory diagram for explaining the operation of the pixel detection unit according to the first embodiment; 3 is a flowchart illustrating a processing procedure of a pixel detection unit according to the first embodiment; It is a block diagram which shows schematic structure of the 2nd process part concerning Embodiment 2 of this invention. 10 is a chart showing an example of an LUT of a gain determination unit according to the second exemplary embodiment; It is a block diagram which shows schematic structure of the 2nd process part concerning Embodiment 3 of this invention. It is a block diagram which shows schematic structure of the area detection part concerning Embodiment 3. FIG. It is a block diagram which shows schematic structure of the 2nd process part concerning Embodiment 4 of this invention. It is a block diagram which shows schematic structure of the area detection part concerning Embodiment 4. FIG. 10 is a chart illustrating an example of a LUT of a gain determination unit according to a fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Frame memory, 2 ... Video signal conversion circuit, 3 ... Remote control, 4 ... Remote control control part, 5 ... CPU, 6 ... Liquid crystal display drive circuit, 7 ... Projection screen, 8 ... Projection optical system, 9 ... Liquid crystal display panel, DESCRIPTION OF SYMBOLS 10 ... Illumination optical system, 11 ... Bus, 12, 13 ... Synchronization separation part, 14 ... AD conversion part, 14a ... Input switching control part, 15 ... Resolution detection part, 17 ... Video processor, 18 ... 1st process part, 19 , 71, 81, 91 ... second processing unit, 20 ... input sequence switching unit, 21, 72, 82, 92 ... area detection unit, 22 ... delay unit, 23, 73, 93 ... gain determination unit, 24 ... adder , 25... Multiplier, 26... High pass filter (HPF), 27... Absolute value luminance difference calculation unit, 28, 85... Binarization unit, 29.

Claims (10)

Based on the difference between the image frames, an area detecting means for detecting a portion of the displayed image that has changed by a predetermined area or more;
Edge enhancement means for performing edge enhancement of a portion detected by the area detection means in the displayed image;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device. Difference detection means for detecting an absolute value luminance difference between image frames;
Based on the detection result of the difference detection means, the own pixel has an absolute value luminance difference equal to or greater than a predetermined threshold value, and other pixels having an absolute value luminance difference equal to or greater than the predetermined threshold value are within a predetermined range around the own pixel. Pixel detection means for detecting a number of pixels or more;
Edge enhancement means for performing edge enhancement of pixels detected by the pixel detection means among images to be displayed;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device.   3. The hold type image display device according to claim 2, further comprising changing means for changing at least one of the predetermined threshold, the predetermined range, and the predetermined number. Difference detection means for detecting an absolute value luminance difference between image frames;
A two-dimensional low-pass filter for removing high-frequency components in a two-dimensional space in which the absolute value luminance differences detected by the difference detection unit are arranged;
Pixel detection means for detecting pixels having an absolute value luminance difference equal to or greater than a predetermined threshold based on the removal result of the two-dimensional low-pass filter;
Edge enhancement means for performing edge enhancement of pixels detected by the pixel detection means among images to be displayed;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device. Difference detection means for detecting an absolute value luminance difference between image frames;
A two-dimensional low-pass filter for removing high-frequency components in a two-dimensional space in which the absolute value luminance differences detected by the difference detection unit are arranged;
Gain determining means for determining a gain of edge enhancement for each pixel based on the removal result of the two-dimensional low-pass filter;
Edge enhancement means for performing edge enhancement based on the determination by the gain determination means;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device. And a gain determining means for determining a gain of edge enhancement for each pixel based on the number of the other pixels within the predetermined range,
4. The hold-type image display device according to claim 2, wherein the edge enhancement unit performs edge enhancement based on the determination by the gain determination unit. Furthermore, an input series setting means for selecting and setting an input series of images,
Gain determining means for determining a gain of edge emphasis by the edge emphasizing means based on setting by the input series setting means;
The hold-type image display device according to claim 1, further comprising: Furthermore, resolution detection means for detecting the resolution of the input image,
Gain determining means for determining a gain of edge enhancement by the edge enhancement means based on a detection result of the resolution detection means;
The hold-type image display device according to claim 1, further comprising: A motion detection means for detecting a portion of the image to be moved based on a difference between image frames;
Edge enhancement means for performing edge enhancement of a portion detected by the motion detection means in the displayed image;
An input series setting means for selecting and setting an input series of images;
Gain determining means for determining a gain of edge emphasis by the edge emphasizing means based on setting by the input series setting means;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device. A motion detection means for detecting a portion of the image to be moved based on a difference between image frames;
Edge enhancement means for performing edge enhancement of a portion detected by the motion detection means in the displayed image;
Resolution detection means for detecting the resolution of the input image;
Gain determining means for determining a gain of edge enhancement by the edge enhancement means based on a detection result of the resolution detection means;
Image display means for displaying the image edge-enhanced by the edge enhancement means;
A hold-type image display device.

Images