JP4292113B2 - Image processing apparatus and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus and an image processing method for reducing the pseudo contour and noise of a display image by performing signal processing on an image display signal and improving the display image quality.

  As a method of reducing noise and pseudo contour of a display image, there is a method of averaging signal values of surrounding pixels (average filter method). This method is known to smooth a significant level difference of the original image, that is, a contour portion, and lose the sharpness of the image. As a method for compensating for this drawback, there is an ε-filter method. This is a method in which a non-linear filter is used so as not to pass a filter when there is a large difference in signal value such as a contour. However, this method also requires a non-linear element as many as the number of pixels constituting the filter, which increases the circuit scale and is substantially difficult to implement.

  Therefore, as a method of improving this method and achieving high image quality even with one nonlinear element, the image signal is blurred through a spatial low-pass filter, the blurred output signal, Take the difference from the original image signal, and if the difference is small, a blurred low-pass filter output can be obtained. Conversely, when the difference is large, this is regarded as a useful signal and the value of the original image signal There is a method of adaptively outputting both components so as to maintain the above (for example, see Patent Document 1).

JP 2000-295497 A

  When the signal is smoothed using the method described in Patent Document 1, there is a problem that a so-called ghost phenomenon appears in which the shadow of the edge is displayed lightly at a position slightly away from the edge of the image. This phenomenon is fundamental and causes image display quality to deteriorate.

  The present invention enables high-quality display by suppressing the side effect of ghosting while taking advantage of the ε-filter method of reducing pseudo contour and noise while preserving the contour of the original signal. The purpose is to provide technology.

  In addition, the present invention provides a method for adjusting the strength of smoothing or not performing smoothing according to the state of the original signal whether it is a contour part or not, and the original contour of the original signal is reduced. An object of the present invention is to provide a technology that enables high-quality display by reducing pseudo contours and noise while being preserved.

  The image processing apparatus according to the present invention can detect a difference between an original signal (each input pixel signal represented by a bit string input to each pixel) and a signal that has passed through an LPF in pixels near the target pixel. Whether to perform coring processing based on the maximum value and the minimum value of the signal is selected, and the selected signal is added to the signal that has passed through the LPF to be output.

  In the image processing apparatus of the present invention, when the original signal is smoothed into an output signal, the user can select the smoothing strength stepwise. Or it is set as the structure which can also select so that smoothing may not be performed.

  By appropriately selecting and controlling signals using the method of the present invention, there are advantages that pseudo contours and noise are reduced, ghosting can be suppressed, and high-quality display is possible. In addition, the circuit scale can be reduced.

  In addition, by appropriately selecting and controlling the smoothing strength and ON / OFF, the user can freely select the smoothing strength of the signal. For example, when the input signal is a contour signal, it is possible to reduce the smoothing strength or not to perform smoothing so that the original contour of the original image can be displayed. In the case of a pseudo contour due to a signal bit shortage, the pseudo contour can be eliminated by increasing the smoothing strength.

  Before describing the embodiment of the present invention, ghost reduction in the method of Patent Document 1 will be considered. For simplicity, the signal sequence is one-dimensional, but the same applies to a two-dimensional case. The input signal series x (n) is smoothed by the method described in Patent Document 1. That is, if the output is y (n), a (i) is a coefficient whose sum is 1.

ｇ（ｘ）を非線形関数として、

Let g (x) be a nonlinear function,

となる。

It becomes.

Here, examples of g (x) include the examples shown in FIGS. FIG. 1 is a diagram showing a characteristic in which the input signal series x has linearity between −ε and + ε and becomes 0 outside this range. FIG. 2 has a mountain-shaped characteristic having a positive slope and a negative slope between x and epsilon. FIG. 3 has a characteristic in which the mountain shape of FIG. 2 is smoothed.
Further, when g (x) is a linear function as shown in FIG. 4, it corresponds to the case of the averaging filter method.

  Here, if the input signal x (n) is a signal as shown in FIG. 5, when g (x) is in FIGS. 1 to 4, each output signal y (n) is (1) Each of the equations has the characteristics shown in FIGS. As is apparent, in FIGS. 6 to 8, a portion (indentation) slightly different from the surroundings at a position slightly away from the position of the contour of the original signal (each input pixel signal represented by a bit string input to each pixel). ) Appears. This is a so-called ghost. FIG. 9 shows the case of the averaging filter method, and the outline of the original signal is lost.

  Hereinafter, an image processing apparatus and an image processing method according to embodiments of the present invention will be described with reference to the drawings. In the present embodiment, description will be made by taking as an example a case of applying to an image processing apparatus and reducing pseudo contours and noise of a display image.

  FIG. 10 is a block diagram showing a configuration example of the image processing apparatus according to the first embodiment of the present invention. As shown in FIG. 10, the image processing apparatus according to the present embodiment includes delay circuits 1 to 5, a weighted addition circuit 6, a Max-Min calculation circuit 7, a subtraction circuit 8, and a coring processing circuit 9. , A signal selection circuit 10 and an addition circuit 11.

  The input video signal is delayed by the delay circuits 1 to 5 and input to the weighted addition circuit 6 and the Max-Min calculation circuit 7. The weighted addition circuit 6 outputs a signal obtained by multiplying each signal by a coefficient and adding the result to the subtraction circuit 8. It functions as a so-called low-pass filter (LPF). Further, the Max-Min calculation circuit 7 obtains the maximum value and the minimum value of the signal in the range around the pixel of interest (n rows and m columns: n and m are values that can be freely set), and the difference between them is obtained. Is calculated and output. The subtracting circuit 8 subtracts the output signal (the signal subjected to the high frequency reduction process) from the weighted adding circuit 6 from the original video signal. The coring processing circuit 9 performs coring processing on the image signal by LUT (Look Up Table). FIG. 11 is a diagram illustrating an example of this coring function. In the circuit according to the present embodiment, an LUT that outputs a coring function value corresponding to an input signal value is used as a method for realizing the coring process.

  In the signal selection circuit 10, depending on the output value of the Max-Min calculation circuit 7, which of the signal subjected to the coring process by the coring process circuit 9 and the signal before the coring process is output is output. Judge and output. More specifically, a threshold value (corresponding to ε of the ε-filter method) is determined as an appropriate value, and when the value of Max-Min is equal to or smaller than the threshold value, the signal subjected to coring processing. If the value is larger than the threshold value, the signal before the coring process is output. For this reason, by adjusting this threshold value, it is possible to freely set to what extent the signal value difference is to be output as the original image. The adder circuit 11 adds the output signal of the weighted adder circuit 6 (the signal subjected to the high-frequency reduction process) and the output signal of the signal selection circuit 10. Thus, a desired output can be obtained.

  The advantages of image processing according to this embodiment will be described below. In the following, for the sake of simplicity, the result of a one-dimensional simulation is shown, but the same result can be obtained even in a two-dimensional case.

  First, the original image is set to a contour that changes from 64 to 192 with an 8-bit signal value. The threshold value ε is 32 in both the method according to the present embodiment and the method described in Patent Document 1. In the method according to the present embodiment, the periphery of the pixel of interest is a range of 15 dots before and after, the LPF uses a simple averaging filter method, and the coring function uses the function shown in FIG. In the method described in Patent Document 1, g (x) is as shown in FIG. A simulation was performed to see how the vicinity of the contour changes under the above conditions.

  FIG. 13 is a diagram showing a calculation result in the case of using the method of the present invention, and FIG. As apparent from FIGS. 12 and 13, in the method described in Patent Document 1, a ghost is generated in the vicinity of the contour, but it is understood that no ghost is generated in the method of the present invention. That is, it can be seen that the ghost can be reduced by the configuration shown in FIG.

  14 and 15 are circuit block diagrams showing another configuration example of the image processing apparatus according to the present invention. The configuration shown in FIG. 14 is a configuration example in which the video signal is also input to the selection circuit 22 and the original video signal and the video signal after smoothing processing are selected based on the difference between the maximum value and the minimum value. FIG.

  The configuration shown in FIG. 15 is a circuit that controls the coring process itself according to the output value of the Max-Min calculation circuit 29. Thereby, for example, when the output value of the Max-Min calculation circuit 29 changes stepwise, flexible control such as changing the degree of coring stepwise becomes possible.

  In the above embodiment, an example is shown in which the difference between the maximum value and the minimum value among the signal values of m × n pixels around the pixel of interest is used as a reference for determination by the signal selection circuit. The values of m and n can be arbitrarily changed.

  In the above embodiment, the smoothing process is controlled by comparing the difference between the maximum value and the minimum value in the signal values with a certain threshold value. For example, the maximum value and the minimum value are controlled. It is also possible to make the threshold variable, such that the threshold value is increased when the difference between and the maximum value is large, and the threshold value is also decreased when the difference between the maximum value and the minimum value is small. . Furthermore, instead of the difference between the maximum value and the minimum value, the standard deviation of the signal value in the surrounding pixels of the target pixel is used as an index. When the value is large, the threshold value is increased, and when the value is small, the threshold value is increased. It is also possible to make the threshold value variable by reducing the threshold value.

  Further, in the above embodiment, the averaging filter method + coring method is used as the smoothing method. However, when the value is equal to or less than the threshold value, the averaged value is output, and the coring process is performed. It is also possible to reduce the circuit scale without performing the above.

  Also, instead of simply controlling the smoothing process with a threshold value, the ratio of the original signal when the difference is large depending on the difference between the maximum value and the minimum value of the signal value around the pixel of interest. If the difference is small, the output signal can be controlled such that the ratio of the smoothed signal is increased.

As described above, the advantage of the ε-filter method is that the pseudo contour and noise are reduced while preserving the contour of the original signal by appropriately selecting and controlling the signal using the method according to the present embodiment. Since the signal processing can be performed with a simple circuit configuration using an LUT, the ghost is further suppressed, and a high-quality display is possible.
A DVD signal has 8-bit color signal information according to the standard, but only about 5 bits are actually effective. In particular, in recent years, the performance of MPEG decoders by software has improved, and there are many opportunities to play DVDs on personal computers (PCs). In addition, there are many opportunities to use a liquid crystal monitor as a display device for a PC. Therefore, the pseudo contour which is not conspicuous due to the LPF on the cathode ray tube television becomes conspicuous on the liquid crystal TV which displays more accurately. As a method for reducing such noise and pseudo contour of a display image, there are a method (average filter method) for averaging signal values of surrounding pixels described in the first embodiment, an ε-filter method, and the like. . When the signal is smoothed using this method, the more the strength of the smoothing, the more the signals of the pseudo contour portion can be smoothed. When the strength is increased, the significant level difference of the original image, that is, the contour of the original original image signal is also smoothed, and the sharpness of the image is lost.

  Therefore, a second embodiment of the present invention will be described. First, before describing the present embodiment, a description will be given of the point that the outline is lost when the smoothing is simply increased using the method described in the first embodiment.

  First, the original image is set to a contour that changes from 64 to 192 with an 8-bit signal value. The threshold ε was 128. In the first embodiment, the area around the pixel of interest is a range of 15 dots before and after, the LPF is a simple averaging filter method, and the coring function is the function shown in FIGS. 20 and 21 depending on the strength of smoothing. Used (coring A: weak, coring B: medium, coring C: strong). A simulation was performed on how the output signal changes depending on the smoothing strength under the above conditions.

  FIG. 22 is a diagram illustrating an example of a result of a simulation performed using spreadsheet software. k = 1.0, 0.3, and 0.1 correspond to coring A, B, and C (weak, medium and strong), respectively. FIG. 23 is a graph corresponding to FIG. As is clear from these figures, the false contour can be reduced by adjusting the parameters of the coring function to increase the smoothness, but at the same time the original image has lost its original contour. End up.

Hereinafter, an image processing apparatus and an image processing method according to the present embodiment will be described with reference to the drawings. In the present embodiment, description will be made by taking as an example a case of applying to an image processing apparatus and reducing pseudo contours and noise of a display image.
[First embodiment]

  The first embodiment is an example in which the coring processing circuit shown in FIG. 18 is used in the image processing apparatus shown in FIG. FIG. 16 is a block diagram illustrating a configuration example of an image processing apparatus according to the present embodiment. As shown in FIG. 16, the image processing apparatus according to the present embodiment includes delay circuits 101 to 105, a weighted addition circuit 106, a Max-Min calculation circuit 107, a subtraction circuit 108, a coring processing circuit 109, a signal A selection circuit 110, an addition circuit 111, and a mode selection circuit 112 are included.

  The input video signal is delayed by the delay circuits 101 to 105 and output to the weighted addition circuit 106 and the Max-Min calculation circuit 107. The weighted addition circuit 106 has a function as a so-called low-pass filter (LPF) that multiplies each signal by a coefficient and then outputs the added signal to the subtraction circuit 108. The Max-Min calculation circuit 107 obtains the maximum value and the minimum value of the signal in the range around the pixel of interest (n rows and m columns: n and m are values that can be freely set), and the difference therebetween. Is calculated and output. The subtraction circuit 108 subtracts the output signal of the weighted addition circuit 106 (the signal subjected to the high frequency reduction process) from the original signal. The coring processing circuit 109 performs coring processing on the image signal by LUT (Look Up Table). In the circuit according to the present embodiment, an LUT that outputs a coring function value corresponding to an input signal value is used as a method for realizing the coring process.

  FIG. 18 is a diagram showing the coring processing circuit 109 according to this embodiment in more detail. The coring processing circuit 109 includes a coring processing circuit (weak) 125, a coring processing circuit (medium) 126, a coring processing circuit (strong) 127, and a signal selection circuit 128, which have different smoothing strengths. ing. The image signals input from the subtraction circuit 108 to the coring processing circuit 109 are cores having different strengths in the coring processing circuit (weak) 125, the coring processing circuit (medium) 126, and the coring processing circuit (strong) 127, respectively. Ring processing is applied.

  In the signal selection circuit 128, the output of the coring processing circuit (weak) 125, the output of the coring processing circuit (medium) 126, the coring processing circuit (in accordance with the value of the mode selection signal output from the mode selection circuit 112) Strong) One of the outputs 127 or a signal that is not processed is selected and output, and becomes an input to the signal selection circuit 110. In this embodiment, the strength of the coring is divided into four levels of weak, medium, strong and off, but for example, two levels of weak and strong, or weak, medium 1, medium 2, strong and off. It may be divided into 5 stages. The way of dividing the coring process strength is arbitrary.

  In the signal selection circuit 110, an appropriate value is determined as a threshold value (corresponding to ε of the ε-filter method), and when the value of Max-Min is equal to or less than the threshold value, the signal subjected to coring processing If the value is larger than the threshold value, the signal before the coring process is selected. For this reason, by adjusting this threshold value, it is possible to freely set to what extent the signal value difference is to be output as the original image. The adder circuit 111 adds the output signal of the weighted adder circuit 106 (the signal subjected to the high-frequency reduction process) and the output signal of the signal selection circuit 110. Thus, a desired output can be obtained.

As described above, the contour of the original signal is stored according to the user's request by appropriately selecting and controlling the smoothing strength and ON / OFF using the method according to the present embodiment, or the signal This makes it possible to reduce pseudo contours and noise due to insufficient number of bits.
[Second Embodiment]

  The second embodiment is an example in which the coring processing circuit shown in FIG. 18 is used in the image processing apparatus shown in FIG. FIG. 17 is a block diagram illustrating a configuration example of an image processing apparatus according to an embodiment of the present invention. As shown in FIG. 17, the image processing apparatus according to the present embodiment includes delay circuits 113 to 117, a weighted addition circuit 118, a Max-Min calculation circuit 119, a subtraction circuit 120, a coring processing circuit 121, and an addition. A circuit 122, a signal selection circuit 123, and a mode selection circuit 124 are included.

  The input video signal is delayed by the delay circuits 113 to 117 and output to the weighted addition circuit 118 and the Max-Min calculation circuit 119. The weighted addition circuit 118 outputs a signal obtained by multiplying each signal by a coefficient and then adding the result to the subtraction circuit 120, and has a function as a so-called low-pass filter (LPF). Further, the Max-Min calculation circuit 119 obtains the maximum value and the minimum value of the signal in the range around the pixel of interest (n rows and m columns: n and m are values that can be freely set). Calculate and output the difference. The subtraction circuit 120 subtracts the output signal of the weighted addition circuit 118 (the signal subjected to the high frequency reduction process) from the original signal. The coring processing circuit 121 performs coring processing on the image signal by LUT (Look Up Table). In the circuit according to the present embodiment, a LUT that outputs a coring function value corresponding to an input signal value is used as a method for realizing the coring process.

  FIG. 18 is a diagram showing the coring processing circuit 121 according to the present embodiment in more detail. The coring processing circuit 121 includes a coring processing circuit (weak) 125, a coring processing circuit (medium) 126, a coring processing circuit (strong) 127, and a signal selection circuit 128, which have different smoothing strengths. ing. The image signals input from the subtraction circuit 120 to the coring processing circuit 121 are cores having different strengths in the coring processing circuit (weak) 125, the coring processing circuit (medium) 126, and the coring processing circuit (strong) 127, respectively. Ring processing is applied. In the signal selection circuit 128, the output of the coring processing circuit (weak) 125, the output of the coring processing circuit (medium) 126, the coring processing circuit (in accordance with the value of the mode selection signal output from the mode selection circuit 124) Strong) One of the 127 outputs or the signal that is not processed is selected and output, and becomes the input of the adder circuit 122.

  In the present embodiment, an example in which the strength of the coring is divided into four levels of weak, medium, strong and off is shown. However, for example, two levels of weak and strong, or weak, medium 1, medium 2, strong Further, it may be divided into five stages such as off. The method of dividing the steps relating to the strength of the coring process is arbitrary.

  The adder circuit 122 adds the output signal from the weighted adder circuit 118 (the signal subjected to the high-frequency reduction process) and the output signal from the coring processor circuit 121. In the signal selection circuit 123, an appropriate value is determined as a threshold value (corresponding to ε of the ε-filter method), and when the value of Max-Min is equal to or less than the threshold value, the output signal of the addition circuit 122 is selected. If it is larger than the threshold value, the original signal is selected. For this reason, by adjusting this threshold value, it is possible to freely set to what extent the signal value difference is to be output as the original image. Thus, a desired output can be obtained.

As described above, the contour of the original signal is stored according to the user's request by appropriately selecting and controlling the smoothing strength and ON / OFF using the method according to the present embodiment, or the signal It is possible to reduce pseudo contours and noise due to the insufficient number of bits.
[Third embodiment]

  The third embodiment is an example in which the coring processing circuit shown in FIG. 19 is used in the image processing apparatus shown in FIG. FIG. 16 is a block diagram showing a configuration example of an image processing apparatus according to the third embodiment of the present invention. As shown in FIG. 16, the image processing apparatus according to the present embodiment includes delay circuits 101 to 105, a weighted addition circuit 106, a Max-Min calculation circuit 107, a subtraction circuit 108, a coring processing circuit 109, a signal A selection circuit 110, an addition circuit 111, and a mode selection circuit 112 are included.

  The input video signal is delayed by the delay circuits 101 to 105 and output to the weighted addition circuit 106 and the Max-Min calculation circuit 107. The weighted addition circuit 106 outputs a signal obtained by multiplying each signal by a coefficient and then adding the result to the subtraction circuit 108, and has a function as a so-called low-pass filter (LPF). The Max-Min calculation circuit 107 obtains the maximum value and the minimum value of the signal in the range around the pixel of interest (n rows and m columns: n and m are values that can be freely set), and the difference therebetween. Is calculated and output. The subtraction circuit 108 subtracts the output signal of the weighted addition circuit 106 (the signal subjected to the high frequency reduction process) from the original signal. The coring processing circuit 109 performs coring processing on the image signal by LUT (Look Up Table). In the circuit according to the present embodiment, an LUT that outputs a coring function value corresponding to an input signal value is used as a method for realizing the coring process.

  FIG. 19 is a diagram showing the coring processing circuit 109 according to this embodiment in more detail. The coring processing circuit 109 has a coring processing LUT 129. In the coring processing LUT 129, a signal obtained by performing coring processing with an appropriate strength on the image signal in accordance with the image signal input from the subtraction circuit 108 and the mode selection signal input from the mode selection circuit 112 is appropriate. Read out from the address, becomes the output of the coring processing circuit 109, and becomes the input of the signal selection circuit 110.

  In this embodiment, the strength of the coring is divided into four stages of weak, medium, strong and off, but for example, two stages of weak and strong, or weak, medium 1, medium 2, strong and off. It may be divided into five stages. The method of dividing the steps relating to the strength of the coring process is arbitrary.

  In the signal selection circuit 110, an appropriate value is determined as a threshold value (corresponding to ε of the ε-filter method), and when the value of Max-Min is equal to or less than the threshold value, the signal subjected to coring processing If the value is larger than the threshold value, the signal before the coring process is selected. For this reason, by adjusting this threshold value, it is possible to freely set to what extent the signal value difference is to be output as the original image. The adder circuit 111 adds the output signal of the weighted adder circuit 106 (the signal subjected to the high-frequency reduction process) and the output signal of the signal selection circuit 110. Thus, a desired output can be obtained.

As described above, by using the method according to the present embodiment to appropriately select and control the strength of smoothing and ON / OFF, the contour of the original signal is saved according to the user's request, or It becomes possible to reduce pseudo contours and noise due to insufficient number of bits of the signal.
[Fourth embodiment]

  The fourth embodiment is an example in which the coring processing circuit shown in FIG. 19 is used in the image processing apparatus shown in FIG. FIG. 17 is a block diagram illustrating a configuration example of an image processing apparatus according to an embodiment of the present invention. As shown in FIG. 17, the image processing apparatus according to the present embodiment includes delay circuits 113 to 117, a weighted addition circuit 118, a Max-Min calculation circuit 119, a subtraction circuit 120, a coring processing circuit 121, and an addition. A circuit 122, a signal selection circuit 123, and a mode selection circuit 124 are included.

  The input video signal is delayed by the delay circuits 113 to 117 and output to the weighted addition circuit 118 and the Max-Min calculation circuit 119. The weighted addition circuit 118 outputs a signal obtained by multiplying each signal by a coefficient and then adding the result to the subtraction circuit 120, and has a function as a so-called low-pass filter (LPF). The Max-Min calculation circuit 119 obtains the maximum value and the minimum value of the signal in the range around the pixel of interest (n rows and m columns: n and m are values that can be freely set), and the difference between them is obtained. Is calculated and output. The subtraction circuit 120 subtracts the output signal of the weighted addition circuit 118 (the signal subjected to the high frequency reduction process) from the original signal. The coring processing circuit 121 performs coring processing on the image signal by LUT (Look Up Table). In the circuit according to the present embodiment, a LUT that outputs a coring function value corresponding to an input signal value is used as a method for realizing the coring process.

  FIG. 19 is a diagram showing a more detailed configuration of the coring processing circuit 121 according to the present embodiment. The coring processing circuit 121 has a coring processing LUT 129. In the coring processing LUT 129, a signal obtained by performing coring processing with an appropriate strength on the image signal according to the image signal input from the subtraction circuit 120 and the mode selection signal input from the mode selection circuit 124 is appropriate. Read out from the address, becomes the output of the coring processing circuit 121, and becomes the input of the signal selection circuit 122.

  In this embodiment, the strength of the coring is divided into four stages of weak, medium, strong and off, but for example, two stages of weak and strong, or weak, medium 1, medium 2, strong and off. It may be divided into five stages. The method of dividing the steps relating to the strength of the coring process is arbitrary.

  The adder circuit 122 adds the output signal from the weighted adder circuit 118 (the signal subjected to the high-frequency reduction process) and the output signal from the coring processor circuit 121. In the signal selection circuit 123, an appropriate value is determined as a threshold value (corresponding to ε of the ε-filter method), and when the value of Max-Min is equal to or less than the threshold value, the output signal of the addition circuit 122 is selected. If it is larger than the threshold value, the original signal is selected. For this reason, by adjusting this threshold value, it is possible to freely set to what extent the signal value difference is to be output as the original image. Thus, a desired output can be obtained.

  As described above, the contour of the original signal can be stored according to the user's request by appropriately selecting and controlling the smoothing strength and ON / OFF using the method according to the present embodiment. it can. Alternatively, it is possible to reduce pseudo contours and noise due to insufficient signal bits.

  Next, an image display apparatus according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 24 is a block diagram illustrating a configuration example of a liquid crystal display device including the image processing device according to the above embodiment. In this embodiment, a liquid crystal television having a built-in tuner as a representative example of a liquid crystal display device and a liquid crystal television having the image processing device shown in the first example (FIG. 16) of the second embodiment will be described. However, the present invention can be similarly applied to image processing apparatuses according to other embodiments. As shown in FIG. 24, the liquid crystal television according to the present embodiment includes a TV signal processing circuit 60. The TV signal processing circuit 60 includes an antenna 61, a tuner 62, a video signal processing circuit 63, and a scaler 64. The data signal and the synchronization signal from the scaler 64 are input to the image processing time according to this embodiment. A data signal (such as a video signal) and a synchronization signal are input to the first delay circuit 101 in the LPF composed of the delay circuits 101 to 105 and the addition weighting circuit 106 in FIG. Is output to the timing controller 71. Further, the synchronization signal is also input to a timing controller 71 described later.

  On the other hand, the liquid crystal panel module 70 includes a timing controller 71, a source driver 72, a gate driver 73, and a TFT liquid crystal panel 74. The liquid crystal panel module 70 receives a data signal from the image processing circuit and a synchronization signal, and receives the timing controller 71. Sends a data signal to the source driver 72 and a scanning signal to the gate driver, thereby displaying an image on the screen of the TFT liquid crystal panel 74.

  In this configuration example, a mode selection signal is given to the coring processing circuit 109 through the mode selection circuit 112. The mode selection circuit 112 receives, for example, a user interface 81 realized by combining a switch such as a remote controller and a menu display, a microcomputer 82 that controls the user interface 81, and setting information captured from the user interface 81 via the microcomputer 82. It can be configured by a register 83 for storing. The setting state of the register 83 is displayed on the liquid crystal television screen 74 by, for example, an OSD (On Screen Display: information display on the display screen) function.

  The functions of the image processing circuit according to the present embodiment are displayed with names such as noise reduction (noise removal), S / N (Signal / Noise) improvement, smoother, etc. in the image quality adjustment menu displayed on the OSD. It is good to be able to select ON / OFF of the function and the degree of smoothing, such as / off, weak (sharp) to strong (soft).

  In the menu setting, the microcomputer passes the image processing circuit when “OFF” is selected, and outputs the coring result to the register 83 when “ON”. Write. Similarly, the comparator threshold value and the attenuation setting are written in the register 83 in accordance with the menu setting weak (sharp) to strong (soft). The image processing circuit operates according to the value stored in the register 83. Specifically, when “strong” is set, the LUT is selected so that the cutoff frequency is set high or the attenuation amount is increased in the coring processing circuit 109, and the comparison threshold is increased in the LPF accordingly. Conversely, when “weak” is set, the LUT is selected so that the cut-off frequency is set low in the coring processing circuit 9 or the attenuation is reduced, and the comparison threshold is lowered in the LPF accordingly. With these functions, it is possible to realize a liquid crystal television that allows the user to perform appropriate image quality settings suitable for the video source.

  As described above, the mode selection circuit 112 corresponds to the mode selected by the user using, for example, a remote control device for an image display device such as a liquid crystal television incorporating the image processing device or an operation switch provided on the main body of the image display device. The strength (mode) of the coring can be selected by the mode selection signal to be performed. In general, whether or not the user performs coring while looking at the screen of the image display device, how strong the coring is performed, or whether or not to perform coring is arbitrary Can be selected.

  In the above description, the method of leaving the mode selection to the user's operation based on the observation of the screen display has been described. However, the mode selection value updated by the user with respect to the default value is updated by the next user. It is possible to keep the setting until it is set, or it may always return to the default value when the power is turned off. Although not shown, a mode selection value may be set in advance according to the type of program, and the value may be determined in advance according to the type of program to be stored in the memory and reproduced. . Furthermore, the past program viewing history and the mode selection value may be stored in association with each other, and the related mode value may be acquired from the memory and automatically set for the same or similar program.

  The present invention is applicable to a display device, for example, a television including a display unit such as a liquid crystal television.

It is a figure which shows the example of the nonlinear function by the method of patent document 1. FIG. It is a figure which shows the example of the nonlinear function by the method of patent document 1. FIG. It is a figure which shows the example of the nonlinear function by the method of patent document 1. FIG. It is a figure which shows the example of the linear function of an averaging filter system. It is a figure which shows the example of the input image signal sequence x (n). It is a figure which shows the example of the output signal at the time of processing the input image signal sequence x (n) using the method of patent document 1. FIG. It is a figure which shows the example of the output signal at the time of processing the input image signal sequence x (n) using the method of patent document 1. FIG. It is a figure which shows the example of the output signal at the time of processing the input image signal sequence x (n) using the method of patent document 1. FIG. It is a figure which shows the example of the output signal at the time of processing the input image signal sequence x (n) using the averaging filter system. 1 is a circuit block diagram illustrating a configuration example of an image processing apparatus according to a first embodiment of the present invention. It is a figure which shows the example of the coring process function used for the image processing apparatus by this Embodiment. It is a figure which shows the process result which simulated using the method of patent document 1 with respect to the input image signal containing an outline. It is a figure which shows the result of having performed the simulation using the system by this Embodiment with respect to the input image signal containing an outline. It is a circuit block diagram which shows another structural example of the image processing apparatus by this Embodiment. It is a circuit block diagram which shows another example of a structure of the image processing apparatus by this Embodiment. It is a block diagram which shows the structural example of the image processing apparatus by the 2nd Embodiment of this invention. It is a block diagram which shows another structural example of the image processing apparatus to which this invention is applied. It is a block diagram which shows a coring processing circuit in more detail. It is a block diagram which shows a coring processing circuit in more detail. It is a figure which shows the example of a coring function. It is a figure which shows the example (what expanded the origin vicinity) of a coring function. It is a figure which shows the result of having performed simulation using the method by 1st Embodiment. It is a graph which shows the result of having performed simulation using the method by a 1st embodiment. It is a figure which shows the structural example of the liquid crystal television using the image processing apparatus by the 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-5 ... Delay circuit, 6 ... Weighted addition circuit, 7 ... Max-Min calculation circuit, 8 ... Subtraction circuit, 9 ... Coring processing circuit, 10 ... Signal selection circuit, 11 ... Addition circuit, 12-16 ... Delay circuit , 17 ... weighted addition circuit, 18 ... Max-Min calculation circuit, 19 ... subtraction circuit, 20 ... coring processing circuit, 21 ... addition circuit, 22 ... signal selection circuit, 23-27 ... delay circuit, 28 ... weighted addition circuit 29 ... Max-Min calculation circuit, 30 ... Subtraction circuit, 31 ... Coring processing circuit, 32 ... Addition circuit, 101 to 105 ... Delay circuit, 106 ... Weighted addition circuit, 107 ... Max-Min calculation circuit, 108 ... Subtraction 109: Coring processing circuit, 110: Signal selection circuit, 111 ... Addition circuit, 112 ... Mode selection circuit, 113 to 117 ... Delay circuit, 118 ... Weighted addition circuit, 119 ... M x-Min calculation circuit, 120 ... subtraction circuit, 121 ... coring processing circuit, 122 ... addition circuit, 123 ... signal selection circuit, 124 ... mode selection circuit, 125 ... coring processing circuit (weak), 126 ... coring processing Circuit (medium), 127: Coring processing circuit (strong), 128: Signal selection circuit, 129: LUT for coring processing.

Claims (23)

A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
A selection circuit that selects one of the output signal of the subtractor and the output signal of the coring processing circuit based on a calculation result of the calculation circuit;
An image processing apparatus having an adder for adding the selected signal by the low-pass pass the signal and the selection circuit a filter,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
An adder for adding the signal that has passed through the low-pass filter and the output signal of the coring processing circuit;
Either the output signal and the input pixel signal of the adder in the image processing apparatus having a selection circuit for selecting based on the calculation result of the arithmetic operation circuit,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor;
An arithmetic circuit for calculating a relationship between a maximum value and a minimum value of a signal in a pixel around the target pixel, and an arithmetic circuit for controlling the coring process according to an output thereof;
An image processing apparatus having an adder for adding an output signal from the signal passed through said low-pass filter and the coring circuit,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. Based on the maximum and minimum values of the signal value near the target pixel in each input pixel signal represented by the bit string input to each pixel of the image display device, it is determined whether or not there is a significant edge in the vicinity. In the image processing apparatus having a circuit that appropriately selects and outputs either the input pixel signal or a signal subjected to noise reduction processing by coring according to the value ,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value .   The image processing apparatus according to claim 1, wherein the coring is performed by a lookup table.   The image processing apparatus according to claim 1, further comprising a surrounding pixel area variable unit that changes a pixel area around the pixel of interest. The image according to any one of claims 1 to 6, further comprising a first threshold value adjusting unit that adjusts the threshold value according to a difference between the maximum value and the minimum value. Processing equipment. Further, according to claim 1, characterized in that it comprises a second threshold adjustment unit standard deviation of the signal values around the pixel as an index to adjust the threshold value based on the magnitude of the value of the pixel of interest 7. The image processing device according to any one of items 6 to 6 . The image processing according to any one of claims 1 to 8 , wherein the smoothing means outputs an averaged value without performing the coring process when the threshold value is less than or equal to the threshold value. apparatus. A low pass filter the input pixel signal is input, represented by a bit string input to each pixel of the images display device,
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
A selection circuit that selects one of the output signal of the subtractor and the output signal of the coring processing circuit based on a calculation result of the calculation circuit;
In an image processing apparatus comprising: an adder that adds a signal that has passed through the low-pass filter and a signal selected by the selection circuit;
In accordance with the difference between the maximum value and the minimum value of the signal values in the pixels around the target pixel, the ratio of the input pixel signal is increased when the difference is large, and the smoothing process is performed when the difference is small. images processor you further comprising a control unit for controlling the output signal to increase the ratio of signal. In accordance with the difference between the maximum value and the minimum value of the signal values in the pixels around the target pixel, the ratio of the input pixel signal is increased when the difference is large, and the smoothing process is performed when the difference is small. The image processing apparatus according to claim 1, further comprising a control unit that controls an output signal so as to increase a ratio of the generated signal. Select whether to perform coring processing based on the maximum value and the minimum value of the signal in the vicinity of the target pixel for the difference signal between the input pixel signal and the signal that has passed through the low-pass filter, and An image processing apparatus characterized in that the selected signal is added to a signal that has passed through a filter and output .
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. Subtracting a signal that has passed through a low-pass filter from the input pixel signal in each input pixel signal represented by a bit string input to each pixel of the image display device;
Selecting the output signal and a signal obtained by performing coring processing on the output signal according to the maximum value and the minimum value of the signal in the pixels around the target pixel;
Wherein adds the selected signal to the signal passed through the low-pass filter, and a step of an output,
The selecting step includes a step of selecting a difference between the maximum value and the minimum value by comparison with a certain threshold value . Filtering each input pixel signal represented by a bit string input to each pixel of the image display device with a low-pass filter;
Subtracting the signal that has passed through the low-pass filter from each input pixel signal;
Coring the output signal from the subtracting step;
Calculating a relationship between a maximum value and a minimum value of a signal in pixels around the pixel of interest;
Selecting one of the output signal in the subtraction step and the output signal in the coring step based on the calculation result of the calculation circuit;
Anda step of adding said filtered signal and said selected signal,
The image processing method according to claim 1, wherein the calculating step includes a smoothing process step of controlling a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value . Filtering by a low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
Subtracting the signal that has passed through the low-pass filter from each input pixel signal, coring the output signal in the subtraction step,
Calculating a relationship between a maximum value and a minimum value of a signal in pixels around the pixel of interest;
Adding the filtered signal and the coring signal;
Selecting either the output signal of the adding step or the input pixel signal based on the calculation result of the calculation circuit ;
The image processing method according to claim 1, wherein the calculating step includes a smoothing process step of controlling a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value . Filtering by a low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
Subtracting the signal that has passed through the low-pass filter from each input pixel signal;
Coring the output signal in the subtracting step;
A step of calculating a relationship between a maximum value and a minimum value of a signal in pixels around the pixel of interest, and a calculation step for controlling the coring step based on an output thereof;
Adding the filtered signal and the coring signal ,
The step of calculating includes a smoothing step of controlling a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value,
The step of controlling the coring step includes a step of changing the strength of the coring based on a difference between the maximum value and the minimum value . A program for causing a computer to execute the image processing method according to any one of claims 13 to 16. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A plurality of coring processing circuits for coring the output signal of the subtractor with different strengths;
A mode selection circuit that selects the outputs of a plurality of coring processing circuits in response to a mode selection signal;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
A selection circuit that selects one of the output signal of the subtractor and the output signal of the coring processing circuit based on a calculation result of the calculation circuit;
An image processing apparatus having an adder for adding the selected signal by the low-pass pass the signal and the selection circuit a filter,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A plurality of coring processing circuits for coring the output signal of the subtractor with different strengths;
A mode selection circuit that selects the outputs of a plurality of coring processing circuits in response to a mode selection signal;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
An adder that adds the signal that has passed through the low-pass filter and the output signal of the coring processing circuit, and either the output signal of the adder or the input pixel signal is based on the calculation result of the calculation circuit. an image processing apparatus having a selection circuit for selecting Te,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor with different strengths by reading different addresses of the coring processing LUT;
A mode selection circuit for reading different addresses of the LUT according to the mode selection signal;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
A selection circuit that selects one of the output signal of the subtractor and the output signal of the coring processing circuit based on a calculation result of the calculation circuit;
An image processing apparatus having an adder for adding the selected signal by the low-pass pass the signal and the selection circuit a filter,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value. A low-pass filter to which each input pixel signal represented by a bit string input to each pixel of the image display device is input;
A subtractor that subtracts a signal that has passed through the low-pass filter from each input pixel signal;
A coring processing circuit for coring the output signal of the subtractor with different strengths by reading different addresses of the coring processing LUT;
A mode selection circuit for reading different addresses of the LUT according to the mode selection signal;
An arithmetic circuit for calculating a relationship between the maximum value and the minimum value of the signal in the pixels around the target pixel;
An adder that adds the signal that has passed through the low-pass filter and the output signal of the coring processing circuit, and either the output signal of the adder or the input pixel signal is based on the calculation result of the calculation circuit. an image processing apparatus having a selection circuit for selecting Te,
An image processing apparatus comprising: a smoothing control unit that controls a smoothing process by comparing a difference between the maximum value and the minimum value with a certain threshold value.   The image processing apparatus according to any one of claims 18 to 21, wherein the mode selection circuit is selected in accordance with a selection operation from an operation unit attached to the image display apparatus. An image display device equipped with the image processing device according to any one of claims 1 to 12 and 18 to 22 .

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