Patent Grant
11081068
This application claims priority from Japanese application JP 2018-233302, filed Dec. 13, 2018. This Japanese application is incorporated herein by reference.
The present disclosure relates to a liquid crystal display device and a video signal processing method performed by the liquid crystal display device, particularly to a liquid crystal display device including two liquid crystal display panels disposed to be laminated.
A technique (see International Publication No. WO2007/040127) of improving contrast by laminating (that is, stacking) two liquid crystal display panels has been proposed in the liquid crystal display device. In the technique, expressive power of black is enhanced using the fact that combined transmittance of two liquid crystal display panels is decided by multiplication of transmittances of the two liquid crystal display panels. On the other hand, a parallax problem is generated due to such a two-plate structure of the liquid crystal display panel.
Conventionally, stereoscopic vision suppression processing of reducing a shadow caused by the parallax by performing filter processing on an image displayed on a sub-panel (that is, the liquid crystal display panel for black-and-white display) is performed as a method for improving the parallax problem caused by the two-plate structure of the liquid crystal display panel.
However, although the conventional stereoscopic vision suppression processing in which the filter processing is used is effective for a place of a black-and-white step in which a straight line is set to a boundary, the stereoscopic vision suppression processing is not properly performed on the place of the black-and-white step, such as a bright spot and a black spot, in which a closed curve like a circle is set to the boundary. For this reason, although the stereoscopic vision of the bright spot is appropriately suppressed, the black spot is stereoscopically seen, or conversely, although the stereoscopic vision of the black spot is appropriately suppressed, the bright spot is stereoscopically seen. As used herein, the bright spot means a high-luminance region surrounded by a low-luminance region. The black spot means the low-luminance region surrounded by the high-luminance region.
The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a liquid crystal display device and a video signal processing method for appropriately lessening the parallax problem caused by the two-plate structure of the liquid crystal display panel regardless of whether a display target is the bright spot or the black spot.
To solve the above problem, a liquid crystal display device that displays an input video signal according to a present disclosure comprises: a first liquid crystal display panel and a second liquid crystal display panel disposed to be laminated; a first video signal generator that generates a first video signal for the first liquid crystal display panel by performing stereoscopic vision suppression processing of suppressing stereoscopic vision due to parallax on the video signal; and a second video signal generator that generates a second video signal for the second liquid crystal display panel using the first video signal, wherein when the video signal indicates a black spot, the first video signal generator performs the stereoscopic vision suppression processing with intensity different from that in a case where the video signal indicates a bright spot.
To solve the above problem, a video signal processing method performed by a liquid crystal display device including a first liquid crystal display panel and a second liquid crystal display panel disposed to be laminated according to a present disclosure comprises: a first video signal generating step of generating a first video signal for the first liquid crystal display panel by performing stereoscopic vision suppression processing of suppressing stereoscopic vision due to parallax on an input video signal; and a second video signal generating step of generating a second video signal for the second liquid crystal display panel using the first video signal generated in the first video signal generating step, wherein in the first video signal generating step, when the video signal indicates a black spot, the stereoscopic vision suppression processing is performed with intensity different from that in a case where the video signal indicates a bright spot.
The present disclosure can be to provide a liquid crystal display device and a video signal processing method for appropriately lessening the parallax problem caused by the two-plate structure of the liquid crystal display panel regardless of whether a display target is the bright spot or the black spot.
Hereinafter, an exemplary embodiment of the present disclosure will be described with reference to the drawings. The following exemplary embodiment illustrates a preferable specific example of the present disclosure. Numerical values, shapes, constituent elements, arrangement positions and connection modes of the constituent elements, steps, and order of the steps illustrated in the following exemplary embodiment are examples, and therefore are not intended to limit the present disclosure. Among the constituent elements in the following exemplary embodiment, the constituent elements not recited in the independent claims indicating the broadest concept of the present disclosure are described as optional constituent elements. Each drawing is not necessarily strictly illustrated. In the drawings, substantially the same configuration is designated by the same reference numerals, and sometimes the overlapping description will be omitted or simplified.
Signal processor 20 performs processing of appropriately lessening the parallax problem caused by the two-plate structure of the liquid crystal display panel regardless of whether the display target is the bright spot or the black spot, generates a first video signal for first liquid crystal display panel 12 and a second video signal for second liquid crystal display panel 14, and outputs the first video signal and the second video signal to first liquid crystal display panel 12 and second liquid crystal display panel 14 respectively. In the specification, the video includes not only moving images but also still images such as a medical image.
First liquid crystal display panel 12 is a panel (in the exemplary embodiment, the black-and-white display panel) that displays the first video signal output from signal processor 20. First liquid crystal display panel 12 includes first timing controller 12a that generates the video signal and a synchronizing signal from the input first video signal, first source driver 12b that displays and drives first display region 12d according to the video signal generated by first timing controller 12a, first gate driver 12c that performs display control of first display region 12d in units of rows according to the synchronizing signal generated by first timing controller 12a, and first display region 12d constructed with pixels arranged two-dimensionally.
Second liquid crystal display panel 14 is a panel (in the exemplary embodiment, the color display panel) that displays the second video signal output from signal processor 20. Second liquid crystal display panel 14 includes second timing controller 14a that generates the video signal and the synchronizing signal from the input second video signal, second source driver 14b that displays and drives second display region 14d according to the video signal generated by second timing controller 14a, second gate driver 14c that performs display control of the second display region 14d in units of rows according to the synchronizing signal generated by second timing controller 14a, and second display region 14d constructed with pixels arranged two-dimensionally.
Maximum value processor 21 is a circuit that extracts a maximum value from the gradation value of each of the three color components included in the input video signal. Specifically, maximum value processor 21 selects and outputs the maximum value of the gradation value (R value, G value, B value) for each pixel with respect to the video signal. Maximum value processor 21 is an example of a processor that converts the input color video signal into the black-and-white video signal, and may be replaced with another system processor (for example, a processor that converts the color video signal into a luminance value using the R value, the G value, and the B value) that converts the input color video signal into the black-and-white video signal. Alternatively, when the input video signal includes a luminance component, maximum value processor 21 may be replaced with a processor that extracts and outputs only the luminance component from the input video signal.
First video signal generator 22 is a circuit that generates the first video signal for first liquid crystal display panel 12 disposed on the back surface side by performing the stereoscopic vision suppression processing of suppressing the stereoscopic vision due to the parallax on the video signal output from maximum value processor 21. First video signal generator 22 includes black-spot and bright-spot detector 23, stereoscopic vision suppressor 24, and gamma corrector (LUT) 25.
Black-spot and bright-spot detector 23 detects whether the video signal output from maximum value processor 21 indicates the black spot or the bright spot, and controls stereoscopic vision suppressor 24 so as to perform the stereoscopic vision suppression processing with intensity different from the case that the bright spot is detected when the black spot is detected. Specifically, black-spot and bright-spot detector 23 instructs threshold processor (threshold) 24c of stereoscopic vision suppressor 24 to change a threshold (an instruction to detect the black spot or to detect the bright spot). For example, black-spot and bright-spot detector 23 calculates a difference (differential value) of the gradation value in a vertical direction, a horizontal direction, a diagonal direction, and the like of the region formed by a collection of at least one pixel, determines that the region is the bright spot when a step in which the luminance increases in all directions going outside the region is detected, and determines that the region is the black spot when a step in which the luminance decreases in all directions going outside the region is detected.
Gamma corrector 25 is a circuit that performs gamma correction on the video signal output from maximum value processor 21. For example, gamma corrector 25 converts the gradation value using a look-up table indicating a gamma characteristic (a relationship between the input gradation value and the output gradation value) emphasizing contrast of the video displayed on liquid crystal display device 10 as illustrated in
Stereoscopic vision suppressor 24 is a circuit that generates the first video signal for first liquid crystal display panel 12 disposed on the back surface side by performing the stereoscopic vision suppression processing on the video signal output from gamma corrector 25. Stereoscopic vision suppressor 24 includes differential processor (differential) 24a, maximum value filter (MaxF) 24b, threshold processor (threshold) 24c, size variable maximum value filter (size variable MaxF) 24d, and second low-pass filter (LPF) 24e.
Differential processor 24a is a circuit that calculates a spatial differential value for the video signal output from maximum value processor 21, for example, a circuit that replaces the gradation value of the pixel with a value (that is, a differential value) obtained by performing filter processing (that is, weighted addition) for differential value calculation on the gradation values of the pixel and peripheral pixels (for example, a total of nine pixels including the pixel and eight peripheral pixels).
Maximum value filter 24b is a circuit that replaces the differential value output from differential processor 24a with the maximum value among the differential values of the pixel and the peripheral pixels (for example, the total of nine pixels including the pixel and the eight peripheral pixels) for each pixels.
Threshold processor 24c is a circuit that instructs size variable maximum value filter 24d of the size of the maximum value filter used in size variable maximum value filter 24d according to the differential value output from maximum value filter 24b. At this point, threshold processor 24c instructs the size of the maximum value filter used in size variable maximum value filter 24d using the threshold decided according to the instruction from black-spot and bright-spot detector 23. As used herein, the size of the maximum value filter means a number of pixels used to calculate the maximum value using the maximum value filter. Threshold processor 24c basically instructs size variable maximum value filter 24d to have a larger size with increasing differential value input from maximum value filter 24b. At this point, threshold processor 24c instructs size variable maximum value filter 24d to have a size corresponding to the differential value input from maximum value filter 24b by changing the threshold used to decide the size, according to the instruction from black-spot and bright-spot detector 23.
Specifically, when receiving an instruction to detect the black spot from black-spot and bright-spot detector 23, threshold processor 24c instructs the size of the maximum value filter to be used for size variable maximum value filter 24d such that the maximum value filter having the larger size is used in size variable maximum value filter 24d than in case of detecting the bright spot.
Size variable maximum value filter 24d is a circuit that replaces the gradation value of the pixel indicated by the video signal output from gamma corrector 25 with the maximum value among the gradation values of the pixel and the plurality of pixels adjacent to the pixel using the maximum value filter having the size instructed from threshold processor 24c. In this case, basically, the processing is one of expanding a white region by spreading the higher gradation value (whiter color) to the peripheral pixels at a place where a black-and-white step is higher (that is, the differential value is larger) in the input video signal.
Second low pass filter (LPF) 24e is a circuit that generates the first video signal for first liquid crystal display panel 12 disposed on the back surface side by spatially smoothing the gradation value indicated by the video signal output from size variable maximum value filter 24d. For example, second low pass filter (LPF) 24e replaces the gradation value of the pixel with an average value of the gradation values of the pixel and peripheral pixels (for example, a total of nine pixels including the pixel and eight peripheral pixels).
Second video signal generator 26 is a circuit that generates the second video signal for second liquid crystal display panel 14 disposed on the display surface side using the first video signal output from first video signal generator 22. Second video signal generator 26 includes inverse gamma corrector (INV-LUT) 26a and multiplier 26b.
Inverse gamma corrector 26a is a circuit that outputs a value (that is, a coefficient) corresponding to inverse conversion of gamma correction performed by gamma corrector 25 with respect to the input first video signal. For example, inverse gamma corrector 26a outputs the coefficient using a look-up table corresponding to the inverse conversion of the gamma correction performed by gamma corrector 25. Multiplier 26b multiplies the video signal (that is, each of the R value, the G value, and the B value) input to signal processor 20 by the coefficient output from inverse gamma corrector 26a.
Using inverse gamma corrector 26a and multiplier 26b, second video signal generator 26 generates the gradation value obtained by dividing the input video signal by the gradation value of the second video signal as the second video signal by multiplying the input video signal by the value obtained by performing the inverse gamma correction on the first video signal.
Consequently, the input video signal is separated into the first video signal and the second video signal such that a result of multiplication of the gradation value of the first video signal and the gradation value of the second video signal is matched with the gradation value of the input original video signal.
A characteristic operation of liquid crystal display device 10 of the exemplary embodiment having the above configuration, a problem that can be generated with respect to the bright spot and the black spot caused by the two-plate structure of the liquid crystal display panel, and a solution (video signal processing method) of the problem by liquid crystal display device 10 will be described below.
As illustrated in a part (a) of
Because the maximum value filter of size variable maximum value filter 24d replaces the gradation value of the pixel with the maximum value among the gradation values of the pixel and the plurality of pixels adjacent to the pixel, the maximum value filter shifts the inclined portion (that is, the gradation place) of the first video signal to the dark region. At this point, size variable maximum value filter 24d largely shifts the inclined portion (that is, the gradation place) of the first video signal to the dark region (that is, a parallax countermeasure amount is increased (the intensity of the stereoscopic vision suppression processing is increased)) at a place where the black-and-white step is increased (that is, the differential value is increased) by the pieces of processing of differential processor 24a, maximum value filter 24b, and threshold processor 24c.
Thus, the parallax countermeasure amount is decided according to the luminance step (differential value) by the stereoscopic vision suppressor 24 including size variable maximum value filter 24d, differentiation processor 24a, maximum value filter 24b, and threshold processor 24c, and the problem that the first video signal is seen through (flare) and the problem that the shadow is seen from the oblique direction (that is, the parallax problem that is three-dimensionally seen) are effectively suppressed.
A problem that can be generated with respect to the bright spot and the black spot due to the two-plate structure of the liquid crystal display panel will be described below.
A part (a1) of
A part (a2) of
A part (a3) of
As can be seen from the parts (a1) to (a3) of
A part (b1) of
A part (b2) of
A part (b3) of
As can be seen from the parts (b1) to (b3) of
As illustrated in the part (c) of
As described above with reference to
These mean that, when the size of the maximum value filter is decided by a method of minimizing the problem region based on the bright spot, application of the identical maximum value filter to the black spot means that the size of the maximum value filter is too small. In other words, the size of the maximum value filter corresponding to the differential value of the black-and-white step is set relatively small when the display target is the bright spot, and the size of the maximum value filter for the identical differential value is set relatively large when the display target is the black spot.
As described above, in the exemplary embodiment, liquid crystal display device 10 decides the size of the maximum value filter corresponding to the differential value of the black-and-white step by the method of minimizing the problem region based on the bright spot, and sets the size of the maximum value filter larger even with the identical differential value when the display target is the black spot. That is, the first video signal subjected to the parallax countermeasure amount different between the bright spot and the black spot is generated. An operation (that is, a video signal processing method) of liquid crystal display device 10 of the exemplary embodiment having these characteristics will be described below.
Maximum value processor 21 extracts the maximum value from the gradation values of the three color components included in the input video signal (S10). Specifically, maximum value processor 21 selects and outputs the maximum value of the gradation value (R value, G value, B value) for each pixel with respect to the video signal.
Gamma corrector 25 performs the gamma correction on the video signal output from maximum value processor 21 (S11). For example, gamma corrector 25 converts the gradation value using the look-up table indicating the gamma characteristic emphasizing the contrast of the video displayed on liquid crystal display device 10 as illustrated in
Subsequently, black-spot and bright-spot detector 23 detects whether the video signal output from maximum value processor 21 indicates the black spot (S12). As a result, when black-spot and bright-spot detector 23 detects that the video signal indicates the black spot (Yes in S12), stereoscopic vision suppressor 24 performs the stereoscopic vision suppression processing on the video signal output from gamma corrector 25 with the intensity higher than that in the case where the bright spot is detected under the control of black-spot and bright-spot detector 23, and outputs the video signal as the first video signal (S13). Specifically, black-spot and bright-spot detector 23 instructs threshold processor 24c of stereoscopic vision suppressor 24 to change the threshold. At this time, when detecting the black spot, black-spot and bright-spot detector 23 instructs threshold processor 24c of stereoscopic vision suppressor 24 to change the threshold such that the maximum value filter having the larger size than the case where the bright spot is detected is used in size variable maximum value filter 24d of stereoscopic vision suppressor 24, so that size variable maximum value filter 24d replaces the gradation value of the pixel indicated by the video signal output from gamma corrector 25 with the maximum value among the gradation values of the pixel and the plurality of pixels adjacent to the pixel using the larger-size maximum value filter instructed by threshold processor 24c. The video signal output from size variable maximum value filter 24d is spatially smoothed by second low-pass filter 24e, and output as the first video signal. Consequently, the first video signal subjected to the stereoscopic vision suppression processing stronger than that in the case where the bright spot is detected is generated when the black spot is detected.
On the other hand, when black-spot and bright-spot detector 23 does not detect that the video signal indicates the black spot (No in S12), stereoscopic vision suppressor 24 performs the stereoscopic vision suppression processing on the video signal output from gamma corrector 25 with normal intensity under the control of black-spot and bright-spot detector 23, and outputs the video signal as the first video signal (S14). Specifically, because black-spot and bright-spot detector 23 does not instruct threshold processor 24c of stereoscopic vision suppressor 24 to change the threshold, size variable maximum value filter 24d replaces the gradation value of the pixel indicated by the video signal output from gamma corrector 25 with the maximum value among the gradation values of the pixel and the plurality of pixels adjacent to the pixel using the normal-size maximum value filter (in the exemplary embodiment, the maximum value filter having the size decided by the method of minimizing the problem region based on the bright spot). The video signal output from size variable maximum value filter 24d is spatially smoothed by second low-pass filter 24e, and output as the first video signal. Consequently, the first video signal subjected to the stereoscopic vision suppression processing with the normal intensity is generated when the black spot is not detected.
Finally, second video signal generator 26 generates the second video signal for the second liquid crystal display panel 14 disposed on the display surface side using the first video signal output from stereoscopic vision suppressor 24 (S15). Specifically, through the processing using inverse gamma corrector 26a and multiplier 26b, second video signal generator 26 generates the gradation value obtained by dividing the input video signal by the gradation value of the second video signal as the second video signal by multiplying the input video signal by the value obtained by performing the inverse gamma correction on the first video signal.
Threshold processor 24c holds a table specifying two types of the relationships in
As can be seen from the part (a) of
As can be seen from the part (b) in
As can be seen from the part (c) of
As described above, liquid crystal display device 10 of the exemplary embodiment is a device that displays the input video signal, and liquid crystal display device 10 includes: first liquid crystal display panel 12 and second liquid crystal display panel 14 disposed to be laminated; first video signal generator 22 that generates the first video signal for first liquid crystal display panel 12 by performing the stereoscopic vision suppression processing of suppressing the stereoscopic vision due to the parallax on the video signal; and second video signal generator 26 that generates the second video signal for second liquid crystal display panel 14 using the first video signal. When the video signal indicates the black spot, first video signal generator 22 performs the stereoscopic vision suppression processing with intensity different from that in the case where the video signal indicates the bright spot.
The video signal processing method of the exemplary embodiment is a video signal processing method performed by liquid crystal display device 10 including first liquid crystal display panel 12 and second liquid crystal display panel 14 disposed to be laminated, and the video signal processing method includes: first video signal generating steps S13 and S14 of generating the first video signal for the first liquid crystal display panel 12 by performing the stereoscopic vision suppression processing of suppressing the stereoscopic vision due to the parallax on the input video signal; and second video signal generating step S15 of generating the second video signal for second liquid crystal display panel 14 using the first video signal generated in first video signal generating steps S13 and S14. In first video signal generating step S13, when the video signal indicates the black spot (Yes in S12), the stereoscopic vision suppression processing is performed with intensity different from that in the case where the video signal indicates the bright spot.
Consequently, the first video signal subjected to the stereoscopic vision suppression processing with the intensity different from that in the case where the video signal indicates the bright spot is generated when the input video signal indicates the black spot. In this case, the parallax difference that the problem region caused by the parallax is enlarged in the bright spot as compared with the black spot is suppressed, and therefore the parallax problem caused by the two-plate structure of the liquid crystal display panel can appropriately be lessened properly even if the display target is the bright spot or the black spot.
First video signal generator 22 includes: gamma corrector 25 that performs the gamma correction on the input video signal; stereoscopic vision suppressor 24 that generates the first video signal by performing the stereoscopic vision suppression processing on the video signal output from gamma corrector 25; and black-spot and bright-spot detector 23 that detects whether the video signal indicates the black spot or the bright spot, and when detecting the black spot, controls stereoscopic vision suppressor 24 to perform the stereoscopic vision suppression processing with intensity higher than that in the case where the video signal indicates the bright spot. Consequently, the intensity of the stereoscopic vision suppression processing is appropriately controlled based on the black spot or the bright spot detected by black-spot and bright-spot detector 23.
Stereoscopic vision suppressor 24 includes size variable maximum value filter 24d that replaces the gradation value of the pixel indicated by the video signal with the maximum value in the gradation values of the pixel and the plurality of pixels adjacent to the pixel, and when detecting the black spot, black-spot and bright-spot detector 23 controls size variable maximum value filter 24d to replace the gradation value of the pixel indicated by the video signal with the maximum value while the number of the plurality of adjacent pixels is increased as compared with the case where the bright spot is detected. Consequently, the size of the maximum value filter used by size variable maximum value filter 24d is changed depending on the detection result of black-spot and bright-spot detector 23, and the parallax problem depending on the bright spot and the black spot is appropriately suppressed.
Stereoscopic vision suppressor 24 further includes second low-pass filter 24e that generates the first video signal by spatially smoothing the gradation value indicated by the video signal output from size variable maximum value filter 24d. Consequently, second low-pass filter 24e obtains the first video signal in which the luminance is gradually changed, so that the parallax problem caused by the two-plate structure of the liquid crystal display panel can be suppressed.
Second video signal generator 26 generates the second video signal by multiplying the video signal by the value obtained by performing the inverse gamma correction on the first video signal. Consequently, because the gradation value obtained by dividing the input video signal by the gradation value of the second video signal is generated as the second video signal, the result obtained by multiplying the gradation value of the first video signal by the gradation value of the second video signal is matched with the gradation value of the input original video signal, and the luminance characteristic of the input original video signal is reproduced when the first liquid crystal display panel 12 and the second liquid crystal display panel 14 are viewed in the overlapping manner.
Liquid crystal display device 10, further includes maximum value processor 21 that extracts the maximum value from the gradation values of three color components included in the video signal. The video signal includes the gradation values of the three color components, and first video signal generator 22 performs the stereoscopic vision suppression processing on the maximum value extracted by the maximum value processor 21. Consequently, the simple process of maximizing the three color components generates the black-and-white video signal necessary for high contrast from the color video signal.
The method for generating the first video signal by changing the intensity of the stereoscopic vision suppression processing according to whether the input video signal indicates the black spot or the bright spot is not limited to the exemplary embodiment.
First video signal generator 22a is identical to first video signal generator 22 of the exemplary embodiment in the circuit that generates the first video signal for first liquid crystal display panel 12 disposed on the back surface side using the corrected video signal output from gamma corrector 25. However, first video signal generator 22a is different from first video signal generator 22 of the exemplary embodiment but differs in that first video signal generator 22a includes suppression processor 27 instead of black-spot and bright-spot detector 23 of the exemplary embodiment. A difference from the exemplary embodiment will mainly be described.
Suppression processor 27 is a circuit that suppresses the fluctuation range of the gradation value indicated by the video signal than in the case where the video signal indicates the bright spot when the video signal output from maximum value processor 21 indicates the black spot. Suppression processor 27 includes first low-pass filter (LPF) 27a that spatially smoothes the gradation value indicated by the video signal output from maximum value processor 21 and maximum value selector (Max(AB)) 27b that selects and outputs larger one of the gradation values of the video signal output from maximum value processor 21 and the filtered video signal obtained by performing the processing of first low-pass filter 27a. For example, first low-pass filter 27a replaces the gradation value of the pixel with the average value of the gradation values of the pixel and the peripheral pixels of the pixel (for example, the total of nine pixels including the pixel and eight peripheral pixels).
Threshold processor 24c of stereoscopic vision suppressor 24 of the modification basically has the same function as that of the exemplary embodiment. However, because the instruction relating to the threshold change is not received from the outside unlike the exemplary embodiment, size variable maximum value filter 24d is instructed on the size of the maximum value filter used in size variable maximum value filter 24d according to the differential value output from maximum value filter 24b using the fixed threshold. For example, the fixed threshold is a value indicated by the solid line in
As can be seen from
As can be seen from
When the processing (S10) of maximum value processor 21 is completed, first low-pass filter 27a of suppression processor 27 spatially smoothes the gradation value indicated by the video signal output from maximum value processor 21 (S20).
Maximum value selector 27b of suppression processor 27 selects and outputs larger one of the gradation values of the video signal (that is, the pre-smoothing signal) output from maximum value processor 21 and the filtered video signal (that is, the smoothed signal) obtained by performing the processing of first low-pass filter 27a (S21).
Subsequently, gamma corrector 25 performs the gamma correction on the video signal output from suppression processor 27 (S11). Stereoscopic vision suppressor 24 performs the stereoscopic vision suppression processing on the video signal output from gamma corrector 25 using the video signal output from suppression processor 27, and outputs the video signal as the first video signal (S22).
Finally, second video signal generator 26 generates the second video signal for the second liquid crystal display panel 14 disposed on the display surface side using the first video signal output from stereoscopic vision suppressor 24 (S15).
As can be seen from the part (a) of
As can be seen from the part (b) of
As described above, when the input video signal indicates the black spot, first video signal generator 22a of the modification includes suppression processor 27 that suppresses the fluctuation width of the gradation value indicated by the input video signal as compared with the case where the input video signal indicates the bright spot. Consequently, when the display target is the black spot, the differential value in the black-and-white step becomes smaller than that in the case where the display target is the bright spot, and stereoscopic vision suppressor 24 performs the stereoscopic vision suppression processing using the maximum value filter having the small size, almost no inclined portion of the first video signal exists inside the black spot similarly to the exemplary embodiment, and the parallax problem is suppressed.
Suppression processor 27 includes: first low-pass filter 27a that spatially smoothes the gradation value indicated by the video signal with respect to the video signal; and
maximum value selector 27b that selects and outputs the video signal having the larger gradation value in the video signal and the filtered video signal obtained by performing processing on the video signal using first low-pass filter 27a. Consequently, a circuit in which the difference between the bright spot and the black spot is reflected in the decision of the differential value in the black-and-white step, namely, the size of the maximum value filter is fabricated by a simple circuit without determining the bright spot or the black spot.
First video signal generator 22a further includes: gamma corrector 25 that performs the gamma correction on the video signal output from suppression processor 27; size variable maximum value filter 24d that replaces the gradation value of the pixel indicated by the video signal with the maximum value among the gradation values of the pixel and the plurality of pixels adjacent to the pixel with respect to the video signal output from gamma corrector 25; and second low-pass filter 24e that generates the first video signal by spatially smoothing the gradation value indicated by the video signal output from size variable maximum value filter 24d. Consequently, the size of the maximum value filter used in the stereoscopic vision suppression processing is changed depending on the processing result (that is, the differential value in the black-and-white step) of suppression processor 27, and the parallax problem depending on the black spot and the bright spot is properly suppressed.
The liquid crystal display device and the video signal processing method of the present disclosure is described above based on the exemplary embodiment and the modification. However, the present disclosure is not limited to the exemplary embodiment and the modification. It is understood that various changes of the exemplary embodiment and the modification that are conceived by those skilled in the art, and other exemplary embodiments obtained by a combination of components of the exemplary embodiment and the modification are also included within the scope of the present disclosure.
For example, in the exemplary embodiment and the modification, the input video signal is the color signal including the R value, the G value, and the B value. However, the input video signal is not limited to such a type of signal. The input video signal may be a color difference signal including Y, Cb, and Cr or a black-and-white signal. First video signal generators 22 and 22a of the exemplary embodiment and the modification perform processing on the black-and-white signal converted from the input video signal, so that the processing can be performed without depending on the type of the input video signal.
In the exemplary embodiment, threshold processor 24c does not distinguish the bright spot and the image other than bright spot from each other in the processing when the display target is not the black spot. Alternatively, threshold processor 24c may distinguish the bright spot and the image other than bright spot from each other. That is, a third curve indicating a relationship in the normal case where the display target is neither the black spot nor the bright spot may be added as a curve indicating the relationship between the differential value and the size of the maximum value filter, the curve being used by threshold processor 24c. In addition to the detection of the bright spot and the black spot, black-spot and bright-spot detector 23 also detects that the display target is neither the bright spot nor the black spot, and instructs threshold processor 24c on the detection result. Consequently, the highly functional liquid crystal display device in which the parallax countermeasure amount is appropriately decided according to the three types of the cases where the display target is the bright spot, the black spot, and other images is constructed.
The present disclosure can be used as the liquid crystal display device including the two liquid crystal display panels disposed to be laminated, particularly as the liquid crystal display device in which the parallax problem caused by the two-plate structure of the liquid crystal display panel is appropriately lessened irrespective of whether the display target is the bright spot or the black spot, for example, as a liquid crystal display device that displays a medical image.
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| JP2018-233302 | Dec 2018 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20200193920 A1 | Jun 2020 | US |
