JP5369526B2 - Image signal processing device, display device, recording / playback device, and image signal processing method - Google Patents

Description

  The present invention relates to a noise reduction method and apparatus for reducing a noise component contained in an image.

Recent television receivers have become larger in screen size and do not display image signals input from broadcasting, communication, storage media, etc., as they are, but display them by increasing the number of pixels in the horizontal and vertical directions by digital signal processing. It is generally done.
Therefore, as a technique for increasing the number of pixels while increasing the resolution by combining a plurality of input image frames (hereinafter abbreviated as frames) into one frame, Patent Document 1, Patent Document 2, Non-Patent Document Document 1 is known.

JP-A-8-336046 JP-A-9-69755 Shin Aoki “Super-resolution processing using multiple digital image data”, Ricoh Technical Report pp.19-25, No.24, NOVEMBER, 1998

  However, when the high resolution processing technology disclosed in Patent Literature 1, Patent Literature 2, and Non-Patent Literature 1 is used, if processing for increasing the resolution of an image is performed, noise components included in the original image are also emphasized. There was a problem.

  In general, the noise component of an image exists in a region where the spatial frequency component of the image is high. Therefore, it is possible to reduce the noise component as described above by applying a spatial low-pass filter to the target image.

  However, if a general low-pass filter is applied to reduce noise, the high-frequency component of the original image is lost at the same time as the reduction of the noise component, and the effect of the high resolution processing itself is reduced. was there.

  The present invention has been made in view of the above problems, and an object thereof is to suppress the generation of noise components while increasing the resolution of an image.

  In order to achieve the above object, an embodiment of the present invention may be configured as described in the claims, for example.

  The generation of noise components is suppressed while increasing the resolution of the image.

  Examples of the present invention will be described below.

  Embodiments according to the present invention will be described below with reference to the drawings.

  In the following description, LPF means “low-pass filter”.

  An image signal processing apparatus according to Embodiment 1 of the present invention will be described with reference to FIG.

  First, an image signal is input to the image processing apparatus (100) from an image signal input (101). Next, the luminance tangent vector search unit (103) detects a luminance tangent vector indicating the tangent direction of the line formed by the luminance signal near the pixel to be processed with respect to the image signal input from the image signal input (101). And the luminance tangent vector is sent to the resolution increasing unit (102) and the edge direction adaptive LPF unit (104). The resolution enhancement unit (102) uses the luminance tangent vector sent from the luminance tangent vector search unit (103) to increase the resolution of the image signal input from the image signal input (101). I do. The edge adaptive LPF unit (104) performs spatial LPF processing corresponding to the luminance tangent vector sent from the luminance tangent vector search unit (103) on the image signal whose resolution has been increased by the resolution increasing unit (102). Apply. The image output unit (105) outputs an image signal obtained by performing the spatial LPF processing by the edge adaptive LPF unit (104).

  The image signal is input, for example, from the image signal input (101) pixel by pixel from the upper left to the right and from the upper to the lower, and the resolution enhancement unit (102), the luminance tangent vector search unit (103), The edge direction adaptive LPF unit (104) sequentially performs processing for each pixel.

  Next, the configuration and operation of the luminance tangent vector search unit (103) according to the present embodiment will be described with reference to FIG. 10, FIG. 11, and FIG.

  First, FIG. 10 shows an operation principle of the luminance tangent vector search unit (103) in the image signal processing apparatus according to the present embodiment. FIG. 5A shows a state in which the subject is reflected in the image frame (1001). FIG. 4B is an enlarged view of a part (1002) of the image of FIG. 4A, and shows the outline of the subject (1003).

  Here, as shown in FIG. 4B, if the luminance value (signal level) of the pixel on the contour line (1003) of the subject is the same, the pixel (1004) at the position (x1, y1) is The luminance is the same as that of the pixel (1005) at the position (x2, y2).

  Here, the luminance tangent vector search unit (103) obtains the coordinates of two points on the same luminance tangent shown in FIG. 8C, and as shown in FIG. The phase differences θH (1007) and θV (1008) are calculated. The vectors indicated by the phase differences θH (1007) and θV (1008) are luminance tangent vectors.

  A specific method for calculating the luminance tangent vector is shown in FIG. In FIG. 11 (a), the actual pixels (1101) arranged in a grid form represent pixels originally present on the frame. In addition, the interpolation pixel (1103) indicates N points (N is a positive integer) of # 1 to #N arranged on the circumference with the pixel (1102) to be processed as the center, and a plurality of neighboring real objects are shown. This is a pixel interpolated using the pixel (1101). Note that the position of the interpolation pixel (1103) is not limited to the position shown in (a) of the figure.For example, as shown in the figure (b), interpolation pixels of N points # 1 to #N ( 1104) may be arranged in a rectangular shape around the central pixel (1102). From the interpolation pixels (1103) or (1104) arranged in this way, select the pixel with the smallest difference from the luminance value of the center pixel (1102), and select the center pixel (1102) and the selected interpolation From the direction of the straight line connecting the pixels (1103) or (1104), the horizontal phase θH (1007) and the vertical phase θV (1008) are obtained.

  FIG. 12 shows a configuration example of the luminance tangent vector search unit (103) for realizing the calculation of the luminance tangent vector.

  First, using the pixel interpolators # 1 (1203-1) to #N (1203-N) for the input frame signal, the interpolation pixel (1103) shown in FIG. A signal at the position of the interpolation pixel (1104) shown in FIG. 11 (b) is generated.

  The pixel interpolators # 1 (1203-1) to #N (1203-N) can use the above-described general interpolation LPF as they are, and thus detailed illustration and description thereof will be omitted. The outputs of pixel interpolators # 1 (1203-1) to #N (1203-N) are output from the signals before pixel interpolation (i.e., luminance tangent vectors) using subtracters (1204-1) to (1204-N). Difference signal with each input signal to the search unit (103), and using the absolute value converters (1205-1) to (1205-N), the luminance value is calculated for each interpolation pixel # 1 to #N. Find the absolute value of the difference. The direction selector (1206) selects an interpolation pixel so that this value (absolute value of luminance value difference) is minimized, and the horizontal direction and vertical direction of the position of the selected interpolation pixel and the center actual pixel position are selected. The direction difference is output as a horizontal phase difference θH (1007) and a vertical phase difference θV (1008).

  Further, the interval (= circle radius) between the center pixel (1102) and the interpolation pixel (1103) in FIG. 11 (a), and the interval between the center pixel (1102) and the interpolation pixel (1104) in FIG. 11 (b). (= 1/2 of the length of each side of the rectangle) corresponds to the magnitude of each value of the horizontal phase difference θH (1007) and the vertical phase difference θV (1008). The radius of the circle and half the length of each side of the rectangle may be fixed values or variable values. Any value may be used as long as the horizontal phase difference θH (1007) and the vertical phase difference θV (1008) do not become integer pixels.

  As described above, the luminance tangent vector search unit (103) described with reference to FIGS. 10, 11, and 12 can calculate a luminance tangent vector indicating the tangent direction of the luminance signal constituting the image.

  Next, the operation and configuration of the resolution increasing section (102) shown in FIG. 1 will be described with reference to FIG. 6, FIG. 7, FIG. 8, and FIG.

  FIG. 6 shows the configuration of the high resolution unit (102). The high resolution unit (102) includes a phase shift up rate unit (610) having a horizontal / vertical up rate unit (601) (602), a horizontal phase shift unit (603), and a vertical phase shift unit (604). And a aliasing component removing unit (612) having aliasing component removing units (605) and (606), pixel interpolation units (607) and (608), and a mixing unit (609).

  In the following, FIG. 6 describes details of the operation of each unit constituting the high resolution unit (102).

  First, the image signal input from the image signal input (101) to the high resolution unit (102) is input to the horizontal / vertical up-rate units (601) and (602). Further, the phase difference θH (1007) and phase difference θV (1008), which are the luminance tangent vector data calculated by the luminance tangent vector search unit (103), are input to the horizontal / vertical up-rate unit (602).

  Here, the horizontal / vertical up-rate unit (602) uses the phase difference θH (1007), and the horizontal / vertical up-rate unit (601) uses the phase difference θH (1007) in the horizontal direction rather than the horizontal up-rate processing of the horizontal / vertical up-rate unit (601). The horizontal up-rate process is performed by shifting the reference position. Similarly, the horizontal / vertical up-rate unit (602) uses the phase difference θV (1008) to make the phase difference θV (1008 in the vertical direction) higher than the vertical up-rate processing of the horizontal / vertical up-rate unit (601). ) Perform horizontal up-rate processing by shifting the reference position. By this processing, the phase shift up-rate unit (610) can output two image signals up-graded with reference to phases that differ by the phase difference θH (1007) and the phase difference θV (1008).

  Next, the two signals output from the horizontal / vertical up-rate units (601) and (602) are input to the horizontal phase shift unit (603) and the vertical phase shift unit (604), respectively. Here, the horizontal phase shift unit (603) performs the horizontal phase shift process on each of the two input image signals, the two image signals that have been subjected to the horizontal phase shift process, and the two that have not been subjected to the horizontal phase shift process. A total of four image signals are output. Similarly, the vertical phase shift unit (604) performs the vertical phase shift process on each of the two input image signals, the two image signals that have been subjected to the vertical phase shift process, and the two that have not been subjected to the vertical phase shift process. A total of four image signals are output.

  Here, a specific configuration for realizing the horizontal phase shift unit (603) and the vertical phase shift unit (604) may be, for example, a configuration as shown in FIG. That is, in FIG. 7, signal processing that is output through the delay units (705) and (707) out of the two input image signals is not performed. On the other hand, the image signal passing through the π / 2 phase shift units (706) and (708) is output with the phase shifted by π / 2. The direction of this phase shift processing is the horizontal direction for the horizontal phase shift unit (603), and the vertical direction for the vertical phase shift unit (604). Here, the π / 2 phase shift units (706) and (708) can be realized by a conversion process called Hilbert transform. In the above example, π / 2 is used as the phase shift amount. However, in order to obtain the effect of the present embodiment, the value is not limited to this, and any value other than 0 or π may be used.

  Next, the aliasing component removal units (605) and (606) in FIG. 6 perform processing on the pixel values of the four image signals output from the horizontal phase shift unit (603) and the vertical phase shift unit (604), respectively. By multiplying and adding the coefficients calculated based on the phase difference θH (1007) and the phase difference θV (1008), the aliasing components of the image signals in the horizontal direction and the vertical direction are reduced.

  Here, a specific configuration for realizing the aliasing component removal unit (605) and the aliasing component removal unit (606) may be, for example, as shown in FIG. That is, the phase difference θH (1007) is input to the coefficient determination unit (805) included in the return component removal unit (605). The coefficient determination unit (805) calculates coefficients C0, C1, C2, and C3 using the phase difference θH (1007) and the equation shown in FIG. Multipliers (801), (802), (803), and (804) are the delay (705), π / 2 phase shift unit (706), delay (707), π / 2 in FIG. 7 of the horizontal phase shift unit (603). The outputs from the phase shift unit (708) are multiplied by coefficients C0, C1, C2, and C3, respectively. An adder (806) adds the results of the multipliers (801), (802), (803), and (804) to generate an image signal. With this configuration, it is possible to generate a high-resolution image with reduced horizontal folding distortion.

  The return component removing unit (606) determines that the input phase difference is the phase difference θV (1008) and that the image signal multiplied by the coefficients C0, C1, C2, and C3 is the vertical phase shift unit (604) of FIG. Except for outputs from the delay (705), π / 2 phase shift unit (706), delay (707), π / 2 phase shift unit (708), it is the same as the return component removal unit (605) Therefore, explanation is omitted. The return component removing unit (606) can generate a high-resolution image with reduced vertical folding distortion.

  Next, the pixel interpolation unit (607) (608) performs pixel interpolation processing in a direction perpendicular to the direction in which each of the aliasing component removal units (605) and (606) reduces the aliasing component, The mixing unit (609) mixes and outputs the output image signals of the pixel interpolation units (607) and (608).

  Note that aliasing distortion is reduced from two image components having different phase differences (that is, output image signals from the phase-shifting up-rate unit (610)) as shown in FIGS. 6, 7, 8, and 9. The principle of the technique for generating a high-resolution image is described in Japanese Patent Laid-Open No. 2008-085411.

  As described above, according to the high resolution unit (102) described with reference to FIGS. 6, 7, 8, and 9, it is possible to generate a high resolution image signal by reducing aliasing distortion from one image. Is possible.

  Next, the operation of the edge direction adaptive LPF unit (104) in FIG. 1 will be described with reference to FIG. FIG. 2 shows an example in which the hatched portion is the object (205) in the image. The luminance tangent vector in the processing target pixel (201) calculated by the luminance tangent vector search unit (103) is the luminance tangent vector (202).

  Here, the edge direction adaptive LPF unit (104) performs a low-pass filter (203) that is weak in the vertical direction of the luminance tangent vector (202) on the target pixel (low-pass filter having a high cut-off frequency) to obtain the luminance tangent vector. Spatial low-pass filter processing is performed by a strong low-pass filter (204) (a low-pass filter with a low cut-off frequency) in the direction parallel to. As a result, it is possible to perform an edge direction adaptive noise removal filter that reduces noise while preserving the edge component of the object (205).

  3A and 3B show examples of spatial LPF coefficients in the edge adaptive LPF unit (104). For example, when the luminance tangent vector is perpendicular to the screen, a spatial LPF as shown in FIG. 3A may be applied to the processing target pixel. When the luminance tangent vector is at an angle of 45 degrees on the upper right or lower left with respect to the screen, a space LPF as shown in FIG. 3B is applied.

Although FIG. 3 shows an example of a spatial filter having 5 taps each in horizontal and vertical directions, the number of taps and filter coefficients are not limited to these. In the direction perpendicular to the luminance tangent vector, it is configured to be a weak low-pass filter (low-pass filter with a high cutoff frequency), and in the direction parallel to the luminance tangent vector, it is a strong low-pass filter (low-pass filter with a low cutoff frequency). do it.
As shown in FIG. 4, the detailed configuration of the edge direction adaptive LPF unit 4 is a switching in which a plurality of spaces LPFs (402) having different low-pass filter strength and directionality are switched in advance according to the luminance tangent vector direction. A configuration having a container (401) may be used.

The detailed configuration of the edge direction adaptive LPF unit 4 is a spatial LPF coefficient setting for setting coefficients of a plurality of low-pass filters having different low-pass filter strengths and directions according to the luminance tangent vector as shown in FIG. A configuration may be employed in which a section (502) is provided and a variable LPF processing section (501) that applies the LPF according to the coefficient set by the spatial LPF coefficient setting section (502).
As described above, according to the edge direction adaptive LPF unit 4 described with reference to FIGS. 2, 3, 4, and 5, an image with respect to a high-resolution image with less aliasing distortion generated by the high-resolution unit (102) A weak low-pass filter is applied in the direction perpendicular to the inner edge direction to prevent the effect of the high resolution processing itself from being reduced. In addition, a strong low-pass filter is applied in the edge direction in the image to reduce noise components.

  Therefore, the edge direction adaptive LPF unit 4 can suppress the generation of noise components while preventing a reduction in the effect of the high resolution processing.

  According to the image signal processing apparatus and the image signal processing method according to the first embodiment of the present invention described above, it is possible to suppress the generation of noise components while increasing the resolution of an image.

  In addition, a process for generating a high-resolution image from one image and a low-pass filter process corresponding to the edge direction are calculated based on a common luminance tangent vector. As a result, it is possible to realize image processing with a smaller amount of calculation than calculating each of the information used for both processes.

FIG. 13 shows an image display apparatus according to Embodiment 2 of the present invention. The image display apparatus according to the present embodiment is an image display apparatus that performs image signal processing described in the first embodiment.
In the figure, an image display device 1300 includes, for example, an input unit 1301 for inputting a broadcast signal, video content, image content, and the like via a broadcast wave including a television signal, a network, and the like, and an input from the input unit 1301 Recording / playback unit 1302 for recording or playing back content, content storage unit 1303 for recording content by the recording / playback unit 1302, and image signal processing described in the first embodiment for video signals or image signals played back by the recording / playback unit 1302 An image signal processing unit 1304 that is the apparatus 100, a display unit 1305 that displays a video signal or an image signal processed by the image signal processing unit 1304, and an audio output unit 1306 that outputs an audio signal reproduced by the recording / reproducing unit 1302 A control unit 1307 that controls each component of the image display device 1300, and a user operating the image display device 1300.
Since the detailed operation of the image signal processing unit 1304 is the same as that of the image signal processing apparatus 100 described in the first embodiment, the description thereof is omitted.
Since the image display device 1300 includes the image signal processing unit 1304 that is the image signal processing device 100 described in the first embodiment, the video signal or the image signal input to the input unit 1301 is reduced in noise with higher resolution. It can be displayed on the display portion 1305 as a video signal or an image signal. Therefore, even when a signal having a resolution lower than that of the display device of the display unit 1305 is input from the input unit 1301, it is possible to perform display with reduced noise while increasing the resolution of the reproduction signal.
Also, when playing back video content or image content stored in the content storage unit 1303, it can be converted into a video signal or image signal with higher resolution and suppressed noise and displayed on the display unit 1305.
Further, the content storage unit 1303 stores a video signal or image signal having a lower resolution than the resolution displayed on the display unit 1305, and the video content or the image content stored in the content storage unit 1303 is reproduced. If image processing of the signal processing unit 1304 is performed, it can be converted into a video signal or image signal with higher resolution and suppressed noise and displayed on the display unit 1305.

Therefore, the content storage unit 1303 can store the video signal or the image signal displayed on the display unit 1305 as content with a smaller data amount.
Further, the image signal processing unit 1304 may be included in the recording / playback unit 1302, and the above-described image signal processing may be performed during recording. In this case, since it is not necessary to perform the above-described image signal processing during reproduction, the processing load during reproduction can be reduced.
Here, it has been described that the above-described image signal processing is performed by the image signal processing unit 1304. However, the image signal processing may be realized by the control unit 1307 and software. In this case, the image signal processing may be performed by the method described in the first embodiment.
According to the image display apparatus according to the second embodiment of the present invention described above, it is possible to perform display while suppressing the generation of noise components while increasing the resolution of an image.

FIG. 14 shows a recording / playback apparatus according to the third embodiment of the present invention. The recording / playback apparatus according to the present embodiment is a recording / playback apparatus configured to perform the image signal processing described in the first embodiment.
In the figure, for example, a recording / playback apparatus 1400 includes an input unit 1301 for inputting broadcast signals, video content, image content, and the like via, for example, a broadcast wave including a television signal, a network, and the like, and an input from the input unit 1301 A recording / playback unit 1302 for recording or playing back the recorded content, a content storage unit 1303 for recording the content by the recording / playback unit 1302, and an image described in the first embodiment in the video signal or image signal played back by the recording / playback unit 1302 An image signal processing unit 1304 that is the signal processing device 100, an image / video output unit 1405 that outputs the video signal or image signal processed by the image signal processing unit 1304 to another device, and the like, and a recording / playback unit 1302 An audio output unit 1406 that outputs an audio signal to another device, a control unit 1307 that controls each component of the recording / playback device 1400, and a user operates the recording / playback device 1400 Comprising the like over The interface unit 1308.
The recording / reproducing apparatus 1400 includes the image signal processing unit 1304 that is the image signal processing apparatus 100 described in the first embodiment, so that the video signal or the image signal input to the input unit 1301 can be generated with higher resolution. As a suppressed high-quality video signal or image signal, it can be output to another device or the like.

Therefore, it is possible to suitably realize a signal conversion apparatus that converts a low-resolution video signal or image signal into a video signal or image signal in which generation of noise is suppressed while increasing the resolution.
In addition, when playing back video content or image content stored in the content storage unit 1303, it can be converted into a video signal or image signal with higher resolution and suppressed noise generation and output to another device or the like. .

Therefore, a recording / playback apparatus that inputs and accumulates a low-resolution video signal or image signal, converts it to a video signal or image signal that suppresses noise generation while increasing the resolution during playback and output, and outputs the video signal is preferable. realizable.
Further, the content storage unit 1303 stores a video signal or an image signal having a lower resolution than the signal resolution output from the image video output unit 1405 to another device, and the video content stored in the content storage unit 1303 or If the image processing of the image signal processing unit 1304 is performed after the reproduction of the image content, it can be converted into a video signal or image signal with higher resolution and suppressed noise generation and output from the image video output unit 1405 to another device. it can.

  Therefore, the content accumulation unit 1303 can accumulate the video signal or the image signal output from the image / video output unit 1405 to another device as content with a smaller data amount.

  Further, the image signal processing unit 1304 may be included in the recording / playback unit 1302, and the above-described image signal processing may be performed during recording. In this case, since it is not necessary to perform the above-described image signal processing during reproduction, the processing load during reproduction can be reduced.

Here, it has been described that the above-described image signal processing is performed by the image signal processing unit 1304. However, the image signal processing may be realized by the control unit 1307 and software. In this case, the image signal processing may be performed by the method described in the first embodiment.
According to the recording / playback apparatus according to the third embodiment of the present invention described above, it is possible to output an input image or an accumulated image while suppressing the generation of noise components while increasing the resolution.

1 is an example of an image processing apparatus according to Embodiment 1 of the present invention. It is an example of operation | movement of the edge direction adaptive LPF part which concerns on Example 1 of this invention. It is an example of the coefficient of the space LPF which concerns on Example 1 of this invention. It is an example of a structure of the edge direction adaptive LPF part which concerns on Example 1 of this invention. It is an example of a structure of the edge direction adaptive LPF part which concerns on Example 1 of this invention. It is an example of a structure of the high resolution part which concerns on Example 1 of this invention. It is an example of a structure of the horizontal or vertical phase shift part which concerns on Example 1 of this invention. It is an example of a structure of the folding | turning component removal part which concerns on Example 1 of this invention. It is an example of the coefficient used by the aliasing component removal which concerns on Example 1 of this invention. It is an example of the operation | movement principle of the brightness | luminance tangent vector search part which concerns on Example 1 of this invention. It is an example of the calculation method of the brightness | luminance tangent vector which concerns on Example 1 of this invention. It is an example of a structure of the brightness | luminance tangent vector search part which concerns on Example 1 of this invention. It is an example of a structure of the image display apparatus which concerns on Example 2 of this invention. It is an example of a structure of the recording / reproducing apparatus which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Image signal input part, 102 ... High resolution part, 103 ... Luminance tangent vector search part, 104 ... Edge direction adaptive low pass filter (LPF) part, 105 ... Image signal output part, 401 ... Pixel signal switching part, 402 ... Low-pass filter group, 501 ... Spatial low-pass filter unit, 502 ... Low-pass filter coefficient determination unit, 601, 602 ... Horizontal / vertical up-rate unit, 603 ... Horizontal phase shift unit, 604 ... Vertical phase shift unit, 605, 606 ... Folded component Removal unit, 607, 608 ... Pixel interpolation unit, 609 ... Mixing unit, 610 ... Phase shift up rate unit, 611 ... Phase shift unit, 612 ... Folding component removal unit, 705,707 ... Delay unit, 706,708 ... π / 2-phase shift unit, 801, 802, 803, 804 ... multiplier, 805 ... coefficient determination unit, 806 ... adder, 1203 ... pixel interpolator, 1204 ... subtractor, 1205 ... absolute value converter, 1206 ... direction selector , 1301 ... Input unit, 1302 ... Recording / playback unit, 1303 ... Content storage unit, 1304 ... Image signal processing 1305 ... Display unit 1306 ... Audio output unit 1307 ... Control unit 1308 ... User interface unit 1405 ... Image output unit 1406 ... Audio output unit

Claims (12)

A luminance tangent vector detection unit that detects a luminance tangent vector indicating a tangent direction of a line formed by a luminance signal in the image;
A high-resolution processing unit that performs high-resolution processing of the image using the luminance tangent vector;
A low-pass filter unit that performs low-pass filter processing by switching a coefficient according to the direction of the luminance tangent vector for the image that has been increased in resolution by the high-resolution processing unit;
The luminance tangent vector detection unit generates a plurality of interpolation pixels positioned in a plurality of directions with respect to a processing target pixel for detecting the luminance tangent vector, and the luminance value of the processing target pixel among the plurality of interpolation pixels. An interpolation pixel having a luminance value with the smallest difference between and a luminance tangent vector based on a difference in horizontal and vertical positions of the processing target pixel and the selected interpolation pixel,
The resolution enhancement processing unit generates a plurality of pieces of image data having different phase differences from one image using a phase difference indicated by the luminance tangent vector detected by the luminance tangent vector detection unit, and the plurality of images Image signal processing characterized in that phase shift processing is performed on the data, and the plurality of image data and the plurality of image data subjected to the phase shift processing are added with a coefficient to reduce the aliasing component apparatus.   The low-pass filter unit increases the resolution according to the direction of the luminance tangent vector detected by the luminance tangent vector detection unit and the plurality of low-pass filter units having different intensity and directionality of the low-pass filter. The image signal processing apparatus according to claim 1, further comprising a switch that switches between the plurality of low-pass filter units applied to the processed image.   The low-pass filter unit, a low-pass filter coefficient setting unit that sets coefficients of a plurality of low-pass filters having different intensity and directionality according to the direction of the luminance tangent vector detected by the luminance tangent vector detection unit; The image signal processing apparatus according to claim 1, further comprising: a variable low-pass filter unit that applies a low-pass filter according to a coefficient set by the low-pass filter coefficient setting unit. An input unit for inputting an image signal;
A luminance tangent vector detection process for detecting a luminance tangent vector indicating a direction of a line formed by the luminance signal in the image signal input to the input unit is performed, and the resolution of the image is increased using the luminance tangent vector. An image signal processing unit that performs low-pass filter processing by switching coefficients according to the direction of the luminance tangent vector for the high-resolution image;
A display unit for displaying an image processed by the image signal processing unit,
The image signal processing unit generates a plurality of interpolation pixels located in a plurality of directions with respect to a processing target pixel for detecting the luminance tangent vector, and out of the plurality of interpolation pixels, the luminance value of the processing target pixel An interpolation pixel having the smallest luminance value is detected, and a luminance tangent vector is detected based on a difference in horizontal and vertical positions between the processing target pixel and the selected interpolation pixel,
Using the phase difference indicated by the detected luminance tangent vector, a plurality of image data having different phase differences is generated from a single image, a phase shift process is performed on the plurality of image data, and the plurality of image data and A display device characterized by performing a process of reducing a aliasing component by multiplying a plurality of image data subjected to the phase shift process by a coefficient and adding the result. The image signal processing unit is applied to an image that has been subjected to the high resolution processing by selecting one filter from a plurality of low pass filters having different strengths and directivities according to the direction of the luminance tangent vector. The display device according to claim 4, wherein: The image signal processing unit sets coefficients of a plurality of low-pass filters having different low-pass filter strength and directivity according to the direction of the luminance tangent vector, and applies the low-pass filter by changing the set coefficients. The display device according to claim 4, characterized in that: An input unit for inputting an image signal;
An accumulator that accumulates image signals input to the input unit;
A reproduction unit for reproducing the image signal accumulated in the accumulation unit;
A luminance tangent vector detection process for detecting a luminance tangent vector indicating a direction of a line formed by a luminance signal in the image signal reproduced by the reproduction unit is performed, and the resolution enhancement process for the image is performed using the luminance tangent vector, An image signal processing unit that performs low-pass filter processing by switching coefficients according to the direction of the luminance tangent vector for the high-resolution image;
An output unit that outputs an image processed by the image signal processing unit,
The image signal processing unit generates a plurality of interpolation pixels located in a plurality of directions with respect to a processing target pixel for detecting the luminance tangent vector, and out of the plurality of interpolation pixels, the luminance value of the processing target pixel An interpolation pixel having the smallest luminance value is detected, and a luminance tangent vector is detected based on a difference in horizontal and vertical positions between the processing target pixel and the selected interpolation pixel,
Using the phase difference indicated by the detected luminance tangent vector, a plurality of image data having different phase differences is generated from a single image, a phase shift process is performed on the plurality of image data, and the plurality of image data and recording and reproducing apparatus it is according to claim Rukoto performing processing for reducing aliasing components are added by multiplying the coefficient and a plurality of image data subjected to the phase shift processing. The image signal processing unit is applied to an image that has been subjected to the high resolution processing by selecting one filter from a plurality of low pass filters having different strengths and directivities according to the direction of the luminance tangent vector. The recording / playback apparatus according to claim 7, wherein: The image signal processing unit sets coefficients of a plurality of low-pass filters having different low-pass filter strength and directivity according to the direction of the luminance tangent vector, and applies the low-pass filter by changing the set coefficients. The recording / playback apparatus according to claim 7, wherein: A luminance tangent vector detection step of detecting a luminance tangent vector indicating a tangent direction of a line formed by a luminance signal in the image;
A resolution enhancement processing step of performing resolution enhancement processing of the image using the luminance tangent vector;
A low-pass filter step that performs low-pass filter processing by switching a coefficient according to the direction of the luminance tangent vector for the image that has been increased in resolution in the high-resolution processing step ;
The luminance tangent vector detection step generates a plurality of interpolation pixels located in a plurality of directions with respect to the processing target pixel for detecting the luminance tangent vector, and the luminance value of the processing target pixel among the plurality of interpolation pixels. An interpolation pixel having a luminance value with the smallest difference between and a luminance tangent vector based on a difference in horizontal and vertical positions of the processing target pixel and the selected interpolation pixel,
The resolution enhancement processing step generates a plurality of image data having different phase differences from one image using the phase difference indicated by the luminance tangent vector detected in the luminance tangent vector detection step, and the plurality of images Image signal processing characterized in that phase shift processing is performed on the data, and the plurality of image data and the plurality of image data subjected to the phase shift processing are added with a coefficient to reduce the aliasing component Method. The low-pass filter step selectively selects the plurality of low-pass filters according to the direction of the luminance tangent vector detected in the luminance tangent vector detection step from a plurality of low-pass filters having different strength and directionality of the low-pass filter. image signal processing method of claim 1 0, wherein the application to a high resolution image in the high resolution processing step by switching. The low-pass filter step sets coefficients of a plurality of low-pass filters having different strengths and directions of the low-pass filter according to the direction of the luminance tangent vector detected in the luminance tangent vector detection step, and based on the set coefficient image signal processing method of claim 1 0, wherein applying the low-pass filter variably.

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