CN100428783C - Image processing device, liquid crystal display device and color correction method - Google Patents

Abstract

The invention discloses an image processing device, comprising: a frame memory for storing a signal of a previous image in a previous frame, and a correction processing unit configured to receive the signal of the previous image and the current image, based on The signal level of the current image is corrected based on the signal level difference between the previous image and the current image, and the correction is performed by applying either: a first correction mode in which the signal level of the previous image and the signal level of the current image The relationship between the correction amount of the signal level is the same for the three primary colors, and the second correction mode for correcting the current image by applying another correction amount to change the input image from the previous image to the current image When , the optical response of the liquid crystal display in all primary colors is completed within one frame display period.

Description

Image processing device, liquid crystal display device and color correction method

technical field

The present invention relates to an image processing device, a liquid crystal display device, and a color correction method for correcting a current image signal level of each target color based on a signal level difference between a previous image and a current image in a previous frame.

Background technique

Liquid crystal display devices are being widely used as computer display devices and television receivers.

Depending on the change pattern of the input voltage, the liquid crystal response of the liquid crystal display device may not sufficiently follow the input voltage (drive voltage).

To overcome this problem, Japanese Patent Laid-Open (B) No. 2616652 discloses a method of temporarily applying a voltage corresponding to a high signal level or a low signal level when switching an image signal to be input to a liquid crystal display device , so as to accelerate the change of liquid crystal alignment, this method is generally called "overdrive method".

Japanese Patent Laid-Open (A) No. 2002-62850 discloses a technique for holding in a table the level of a temporarily applied correction voltage, such as the amount of correction or the amount of overdrive.

Contents of the invention

However, the above-mentioned technique disclosed in the latter patent publication may sometimes have a disadvantage that, in a pixel triplet of three primary colors displaying a color mixed by two or three colors, when the rate of change of the signal level differs from color to color , the specific color will be apparent.

This is caused by the response characteristics of liquid crystals. That is, the liquid crystal has such a characteristic that the movement of the liquid crystal for changing the color from a black level to a low grayscale (grayscale) level is slower than the movement from a black level to a high grayscale level, which causes the response speed difference. This results in image persistence (image delay or lag), ie a situation where a particular color is apparent.

Increasing the amount of overdrive (correction) used to change the color from a black level to a lower grayscale level with the aim of reducing the red persistence of the image often results in eg overshooting, resulting in noise components or loss of high grayscale levels level effect. Conversely, a reduction in the amount of correction used to change the color from black levels to high grayscale levels (e.g. to the red component in skin tones like pale yellow) results in a decrease in the overall response rate of the liquid crystal, so overdrive cannot be obtained general effect.

It is desirable to avoid or suppress generation of image persistence with respect to a specific color when improving the response of a moving image by applying a so-called overdrive method.

According to one embodiment of the present invention, an image processing device for processing an image to be input into a liquid crystal display device is provided, comprising:

a frame memory for storing the signal of the previous image in the previous frame, and a correction processing unit configured to receive the signal of the previous image and the signal of the current image as input, and based on the Correcting the signal level of the current image based on a signal level difference between the previous image and the current image, wherein the correction processing unit performs the correction by applying one of: a first correction mode, wherein the The relationship between the correction amount of the signal level of the previous image and the signal level of the current image is the same for each of the three primary colors, and the second correction mode is used to change the input image from the When the previous image is converted into the current image, correcting the current image of at least one color of the three primary colors by applying a second correction amount different from the first correction amount of the first correction mode, so as to display within one frame display period The optical response of the liquid crystal display device in all primary colors can be completed within the time limit.

The correction processing unit according to an embodiment of the present invention may be modified to have, for each of the three primary colors, an image conversion table configured to receive signals of the previous image and the current image as input , specifying the corrected signal level of the current image by applying the first correction mode or the second correction mode to the input signal level of the previous image and the input signal level of the current image, and output result.

The correction processing unit according to an embodiment of the present invention may be modified to have a color level comparison part configured to receive the signals of the previous image and the current image as input, and for each of the three primary colors The signal levels of the input previous image and the input current image are compared by a color, and one of the first correction mode and the second correction mode is selected based on the comparison result.

In the above situation, the correction processing unit according to the embodiment of the present invention may be modified to have a first image conversion table configured to, for each color, convert the selected A current image input in a correction mode is converted into a current image whose signal level is corrected based on the same signal level relationship for the three primary colors, and the result is output; and a second image conversion table, which is converted by configured to convert, for each color, the current image input in the selected second correction mode to a current image whose signal level has been corrected by applying the second correction amount in at least one of the three primary colors. image, and output the result.

Alternatively, the correction processing unit according to an embodiment of the present invention may be modified to have a first correction amount table configured to hold a first correction amount for each color, and at the selected first In the correction mode, the signal of the current image is received as an input, and a first correction amount corresponding to the input signal level of the current image is output; a difference correction amount table, for at least one color in the three primary colors, the difference The correction amount table is configured to hold the difference between the first correction amount and the second correction amount for each color, and in the selected second correction mode, the output is based on the color level comparing means The difference of the color specified by the comparison result; the adder-subtractor, for at least one color in the three primary colors, the adder-subtractor is configured to, for each color, the difference output from the difference correction scale added to the first correction amount output from the first correction amount table, or subtracted from the first correction amount output from the first correction amount table by a difference output from the differential correction amount table, and outputting the second correction amount; and an adder configured to receive the signal of the current image as an input, and output the first correction amount output from the first correction amount table for each color Or the second correction amount output from the adder-subtractor is added to the input current image, and a corrected signal of the current image is output.

Alternatively, the correction processing unit according to an embodiment of the present invention may be modified to have a first correction amount table configured to hold a first correction amount for each color, and at the selected first In the correction mode, the signal of the current image is received as an input, and the first correction amount corresponding to the input signal level of the current image is output for each color; the second correction amount table is for at least one of the three primary colors color, the second correction amount table is configured to maintain a second correction amount for each color, and output a second correction amount for each color in the selected second correction mode; switch, the switch is configured to select one of the first correction amount table and the second correction amount table based on a comparison result of the color level comparison part; and an adder configured to receive a signal of the current image As an input, the first correction amount or the second correction amount input based on a selection result of the switch is added for each color, and a corrected signal of the current image is output.

The color level comparison part according to an embodiment of the present invention can be modified to average the signal levels of a plurality of pixels adjacent to each color in the liquid crystal display device in units of pixel triplets of the three primary colors, and by applying the average The latter signal levels are compared for each color.

The correction processing unit according to an embodiment of the present invention may be modified to have a correction amount generating part configured to intermittently hold the first correction amount and the A portion of each of the second correction amounts, and an unheld correction amount is generated from the held correction amount by interpolation.

According to an embodiment of the present invention, a liquid crystal display device is provided, including: a liquid crystal display device for displaying an image; a frame memory for storing a signal of a previous image in a previous frame, and a correction processing unit, the correction processing A unit configured to receive the signal of the previous image and the signal of the current image as input, correct the signal level of the current image based on a signal level difference between the previous image and the current image, and correct The final signal is output to the liquid crystal display device, wherein the correction processing unit executes the correction by applying one of the following: a first correction mode in which the signal level of the previous image and the signal level of the current image The relationship between the correction amounts of the signal levels is the same for each of the three primary colors, and a second correction mode for changing the input image from the previous image to the current image by applying The second correction amount different from the first correction amount in the first correction mode is used to correct the current image of at least one color in the three primary colors, so as to complete the optical correction of the liquid crystal display device in all primary colors within one frame display period. response.

According to an embodiment of the present invention, there is provided a color correction method for performing color correction of an image to be input, comprising the steps of: delaying the image to be input for each frame, and After the signal level difference between the previous image to be input and the current image to be input without being delayed determines the image portion transformed into a predetermined color to be corrected in the image, by switching the first correction mode to A second correction mode to correct the color in the image portion of the current image transformed into the color to be corrected, wherein in the first correction mode, the signal level of the previous image is the same as that of the current image The relationship between the correction amounts of the signal levels of the three primary colors is the same for each of the three primary colors, and the second correction mode is applied to at least one of the three primary colors in the same manner as the first correction mode of the first correction mode. A second correction amount with a different correction amount.

According to the above configuration, the correction processing unit performs signal level correction (color correction) for each of three primary colors, for example, by applying the first correction mode or the second correction mode. In the first correction mode, color correction is performed with the same first correction amount for a plurality of primary colors. In the second correction mode, correction is performed with a correction amount (second correction amount) different from that of the other color or two colors (first correction amount) for at least one color.

According to the present invention, there is the advantage that when improving the response of moving images by applying the so-called overdrive method, generation of image persistence with respect to specific colors is avoided or suppressed.

Description of drawings

Details of the above and other features of embodiments of the present invention can be more clearly seen with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram showing an image processing apparatus according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing an image processing apparatus according to a second embodiment;

FIG. 3 is a schematic diagram showing the composition of a first image conversion table;

FIG. 4 is a block diagram showing an image processing apparatus according to a third embodiment;

FIG. 5 is a block diagram showing an image processing apparatus according to a fourth embodiment;

6 is a schematic diagram showing the distribution of skin color in a cross-section of a color cylinder;

7A is a schematic diagram showing display characteristics after applying the first method, and FIG. 7B is a schematic diagram showing display characteristics after applying the second method; and

FIG. 8 is a view showing an exemplary pixel area to be averaged.

Detailed ways

Preferred embodiments according to the present invention will be described more specifically below with reference to the accompanying drawings.

An image processing apparatus according to an embodiment of the present invention performs correction processing of an image to be input to a liquid crystal display device by applying a signal of a previous image in a previous frame and a signal of a current image to be corrected. This correction processing is defined as processing of correcting the current image signal level of each color based on the signal level difference between the previous image and the current image. A liquid crystal display device according to an embodiment of the present invention has a liquid crystal display device and respective constituent units of the above-described image processing device configured to perform signal level correction (color correction) for each color of an image to be input, and The corrected signal is input to the liquid crystal display device.

This correction processing includes a first correction mode and a second correction mode, and is performed using one of them.

The first correction mode is defined as a correction mode in which the relationship between the signal level of the previous image and the correction amount of the signal level of the current image is correct for the three primary colors of red (R), green (G) and blue (B). It is the same for each color.

The second correction mode is defined as a correction mode that preferably corrects at least the RGB One of the current image signals, so as to complete the optical response of the liquid crystal in all colors within one frame display period. Note that in the first correction mode, the relationship is determined so that the optical response of the liquid crystal in all colors is completed within one frame display period.

An exemplary embodiment of an image processing apparatus that can perform the above-described correction processing will be described hereafter.

first embodiment

FIG. 1 shows a block diagram of an image processing apparatus of a first embodiment.

The image processing apparatus 1A of the first embodiment has a frame memory 2 and an image replacement memory 3 as storage means.

The frame memory 2 receives as input current frame image data D(n) to be corrected, delays it by one frame display period, and outputs the delayed image as previous frame image data D(n-1).

The image conversion memory 3 can pass (omitted in the figure) for example an image conversion table for the first correction mode (first image conversion table), an image conversion table for the second correction mode (second image conversion table) and A selection table for selecting one of the first image conversion table and the second image conversion table is implemented. The image conversion memory 3 may have an image conversion table for each color to be corrected (for example, human skin color such as buff).

The selection table is defined as a table prepared according to a certain condition for selecting one of the first image conversion table, the second image conversion table, and the other image conversion tables. The selection of the table will be based on the respective signal levels R(n), G(n) and B(n) in the RGB of the current frame image data D(n) and in the RGB of the previous frame image data D(n-1) The respective signal levels R(n-1), G(n-1) and B(n-1) are performed. The selection of the table may be performed by a CPU, not shown, or in such a manner that the selection table outputs an enable signal to any image conversion table among the accessible image conversion tables. The mode switching means is realized by the above configuration.

Specifically, when considering each pair of red signal levels R(n) and R(n-1), green signal levels G(n) and G(n-1), and blue signal levels B(n) and B When there is almost no difference between (n-1), the first image conversion table is selected.

When the signal level difference of each RGB between the previous frame image and the current frame image is detected from black level or other low signal level to the color to be corrected (e.g. human skin color such as light yellow in the current embodiment) A second image conversion table for correcting skin tones is selected when the signal level changes. If there is another color to be corrected, another image conversion table for correcting that color can be selected in the same manner.

The signal level of each RGB output from the second image conversion table is set to a certain value so that when the signal is input to the liquid crystal display (LCD) driver 11 to drive the LCD panel (liquid crystal display device) 10, the required Colors are fully displayed within one frame display period in the current frame image.

Note that the signal level of the signal output by the first image conversion table is the same for each RGB color, which is the same as the overdrive method in the prior art, and the signal level is set to a certain value to Such that when the signal is input to the LCD driver 11 to drive the LCD panel 10, the desired color is completely displayed within one frame display period in the current frame image.

In the first embodiment, selection of the first correction mode and the second correction mode is performed by a selection table.

In contrast, in the following second to fourth embodiments, a color level comparator is provided instead of a table to perform a selection function.

second embodiment

Fig. 2 is a block diagram of an image processing apparatus of a second embodiment.

The image processing apparatus 1B of the second embodiment has a frame memory 2 and a color level comparator 4 , a first image conversion table 31 , and a second image conversion table 32 as mode switching means.

The color level comparator 4 does not receive the previous frame image data D(n-1) and the current frame image data D(n) as an input in units of RGB pixel triplets, compares the previous frame image and the current frame image data D(n) for each color The signal level of the current frame image, and detects whether the image transformation is a change to the color to be corrected, or detects whether a signal of a certain color other than a specific color is included based on the signal level change amount and signal level range of each color The possibility that changes in levels are delayed in image transitions causing specific colors to be emphasized. Furthermore, based on the detected result, when the specific color becomes conspicuous immediately after the image conversion, the comparator 4 outputs the current frame image data D(n) and the previous frame image data D(n−1) data to the first The second image conversion table 32, otherwise when it is not obvious, the comparator 4 outputs the current frame image data D(n) and the previous frame image data D(n−1) data to the first image conversion table 31.

Brightness conversion (image data conversion) of the first correction mode is performed for each color by the first image conversion table 31 , and image data conversion of the second correction mode is performed by the second image conversion table 32 . The converted current frame image data D _new (n) is output to the LCD driver 11 , and the LCD panel 10 displays an image based on the output data (signal) from the LCD driver 11 .

FIG. 3 shows the composition of the first image conversion table 31 .

In the figure, the image (pixel) data signal of each RGB is assumed to be a signal of 8-bit data, and each color is displayed in 256 gray levels (gray scales) indicated by decimal numbers 0 to 255.

In this case, a table for inputting 16-bit data may be required to specify the corrected gray scale from the previous frame of 256 gray scales and the current frame of 256 gray scales, but its storage capacity may be too large . Therefore, pixel data having a reduced gradation level is stored in FIG. 3 when it is assumed that interpolation processing is performed. Means for performing interpolation processing (omitted in FIG. 2 ) is provided on the input side of the LCD driver 11, for example, and can generate an entire frame image by interpolation processing. Any method of linear interpolation, 3-point interpolation, and other linear interpolation or nonlinear interpolation can be used as the interpolation method.

The first image conversion table 31 shown in Fig. 3 is all the same for each color of RGB, when the signal level of the current frame is lower than the signal level of the previous frame, it converts the signal level of the current frame to be lower than the signal level of the current frame Otherwise, when it is higher than the signal level of the previous frame, it converts the signal level of the current frame to a signal level value higher than the signal level of the current frame.

In FIG. 3, for example, when the signal level of the previous frame is assumed to be "128" and the signal level of the current frame is "160", the data "172" higher than the signal level of the current frame is designated and used as the signal level of the current frame The corrected signal level of is output. The correction amount in this case (hereinafter referred to as "first correction amount") becomes "12 (=172-160)".

Note that when the signal level of the previous frame is the minimum value 0, data 0 is held without depending on the signal level of the previous frame, and when the signal level of the previous frame is the maximum value "255", the data "255" be kept.

The second image conversion table 32 (details of which are omitted) is defined as a table such that the first image conversion table 31 (FIG. 3) is corrected so that specific colors are not conspicuous in the overall combination of gray scales. Hereinafter, the corrected correction amount is referred to as "second correction amount", and the difference between the second correction amount and the first correction amount is referred to as "difference correction amount".

third embodiment

Fig. 4 is a block diagram of an image processing apparatus of a third embodiment.

The image processing device 1C of the third embodiment has a frame memory 2 and a color level comparator 4A, and also has a first correction amount table 51, a differential correction amount table 50, a red (R) adder-subtractor 6r, and a red (R) adder 7r, green (G) adder-subtractor 6g and green (G) adder 7g, and blue (B) adder-subtractor 6b and blue (B) adder 7b.

The color level comparator 4A receives the previous frame image data D(n-1) and the current frame image data D(n) as input in units of RGB pixel triplets, and compares the previous frame image and the current frame image data D(n) for each color. The signal level of the current frame image, and detects whether the image transformation includes a change to the color to be corrected, or detects whether a signal of a certain color other than a specific color is included based on the signal level change amount and signal level range of each color The possibility that changes in levels are delayed in image transitions causing specific colors to be emphasized. Furthermore, based on the detected result, when the specific color becomes conspicuous immediately after image conversion, the comparator 4A outputs a signal S4A including differential information to the differential correction amount table 50, otherwise when it is not conspicuous, the comparator 4A This information is not output. In each case, the color level comparator 4A outputs the current frame image data D(n) and the previous frame image data D(n−1) to the first correction amount table 51 .

The first correction amount table 51 designates the correction amount of the first correction mode (first correction amount), which is the same for each color of RGB, and outputs the correction amount. That is, from the first correction amount table 51, the first red (R) correction amount Lr1, the first green (G) correction amount Lg1, and the first blue (B) correction amount Lb1 are respectively output to the R adder-subtractor 6r , G adder-subtractor 6g and B adder-subtractor 6b.

In the first correction mode, the adjustment of the correction amount (addition and subtraction of the differential correction amount) for unclear specific colors is unnecessary, so the first R correction amount Lr1, the first G correction amount Lg1, and the first B correction amount The quantity Lb1 passes through adder-subtractors 6r, 6g, and 6b, and is input to an R adder 7r, a G adder 7g, and a B adder 7b.

Also, in the second correction mode, the signal S4A including difference information is input to the difference correction amount table 50, which specifies the difference correction amount for each color based on the signal S4A including difference information, and outputs the result . That is, from the differential correction amount table 50, the red (R) differential correction amount ΔLr, the green (G) differential correction amount ΔLg, and the blue (B) differential correction amount ΔLb are output to the R adder-subtractor 6r, and the G adder-subtractor 6r. Device 6g, and B addition and subtraction device 6b.

In R adder-subtractor 6r, R differential correction amount ΔLr is added to or subtracted from first R correction amount Lr1, and the result is input to R adder 7r as second R correction amount Lr2. In the same manner as above, in the G adder-subtractor 6g, the G differential correction amount ΔLg is added to or subtracted from the first G correction amount Lg1, and the result is obtained as the second G correction amount Lg2. Input G adder 7g. Furthermore, in the B adder-subtractor 6b, the B differential correction amount ΔLb is added to or subtracted from the first B correction amount Lb1, and the result is input to the B adder as the second B correction amount Lb2 7b. Control information on whether each adder-subtractor performs addition processing or subtraction processing may be included in the differential correction amount to be input, or received separately as an input from the color level comparator 4A.

The current frame image data D(n) of each color is input to the adders 7r, 7g, and 7b, and is added to the second correction amounts Lr2, Lg2, and Lb2, thereby being converted into new current frame image data D _new (n ).

The converted current frame image data D _new (n) is output to the LCD driver 11 , and the image is displayed on the LCD panel 10 based on the output from the LCD driver 11 .

Fourth embodiment

FIG. 5 shows a block diagram of an image processing apparatus of a fourth embodiment.

The fourth embodiment is the same as the third embodiment in the basic operation of adding the correction amount to the current frame image data D(n), and the difference from the third embodiment is the way of generating the correction amount. That is, in the fourth embodiment, the second correction amount is not generated by addition and subtraction of differential correction amounts, but is generated by a table holding the results. The first correction amount and the second correction amount are switched by a switch.

As a configuration for performing the above-described operations, the image processing apparatus 1D shown in FIG. 5 has a second correction amount table instead of the difference correction amount table 50 shown in FIG. 4 , and also has a switch 8r for each color, 8g and 8b, switches 8r, 8g and 8b are used as mode switching switches to replace the adder and subtractor 6r, 6g and 6b shown in FIG.

The basic operation of the color level comparator 4B of this embodiment is the same as that of the color level comparator 4A shown in FIG. The current frame image data D(n) and the previous frame image data D(n−1) of RGB are output to the second correction amount table 52 .

The second correction amount table 52 specifies the correction amount of the second correction mode for each color based on the input current frame image data D(n) and the input previous frame image data D(n−1) of each color, which The correction amount is the same for each color of RGB, and the result is output. That is, from the second correction amount table 52, the second R correction amount Lr2, the second G correction amount Lg2, and the second B correction amount Lb2 are respectively output to the red (R) switch 8r, green (G) switch 8g, and blue (B) Switch 8b.

Each of the switches 8r, 8g, and 8b controls whether to independently output the first correction amount or the second correction amount in RGB. Therefore, the correction amounts outputted through the switches are added to the respective color data of the current frame image data D(n) by the adders 7r to 7b, thereby generating new current frame image data _Dnew (n) of each color, and the image uses the New current frame image data D _new (n) is displayed. Therefore, a specific color is corrected so that the persistence of the image is not noticeable, and other colors are corrected by adjusting the hue of the entire pixel triplet so as to be slightly different from the desired color if necessary.

An example of processing realized with specific value examples of the color level comparator, first correction amount, second correction amount, and differential correction amount is described below with reference to skin color correction in display image conversion from black level to skin color.

Processing example of the color level comparator

In the color level comparators 4 (FIG. 2), 4A (FIG. 4), 4B (FIG. 5), for each RGB pixel triplet, the previous frame (n- 1) Data (previous frame image data D(n-1)) and current frame (n) data (current frame image data D(n)) are compared, and the comparison may be sparse sometimes.

Based on the comparison result, a decision is made as to whether or not the previous frame (n-1) data is black level.

As an example of the conditions for the above judgment, when the entire pixel data of each RGB is included in the lower range of 256 gray levels from 0 to 255 (for example, the range from 0 to 32), the pixel triplet is judged Whether the current frame(n) data in is included in the black level.

A decision is made as to whether the current frame(n) data is included in a skin tone or near-skin tone color range such as light yellow. Two examples of conditions for this decision will be described below.

In the first condition example, skin color or a color range including skin color is specified from the signal level difference among any two or three colors in the data of the current frame (n) or from a combination thereof. When the standard value of skin color is assumed to be (R, G, B)=(250, 200, 96) in 256 gray levels, for example, the color range including skin color is between the maximum signal level R and the minimum signal level B The difference (R-B) is included in the range of about 150 to 60 while being detected. Furthermore, when the color range to be detected is limited to skin color, the above color difference (R-B) is combined with another color difference (R-G) and/or (G-B) to limit the color range including skin color.

In a second conditional example, an HSV (hue, saturation and value) conversion is applied, which is preferably applied to more accurately detect skin tones. Perform HSV conversion on RGB data, so that it is easier to realize skin color judgment.

In HSV conversion, a color column similar to a Munsell color stereogram is extracted from RGB data and applied.

Figure 6 shows the distribution of skin color in the color column section.

In the figure, each color data in RGB is normalized in the range of 0 to 1, the value V is 0 to 1, the hue H is 0 to 360 degrees, and the saturation S is 0 to 1. Note that while the scales for Hue H and Saturation S are shown, the scale for Value V is perpendicular to the paper, so the scattered dots for Value V are overlapping and their vertical values are not indicated.

By applying each color data (R, G, B), the value V and saturation S are expressed by the following formulas (1-1) and (1-2), and the hue H is expressed by the following formulas (2-1) to (2- 3) Expression. The condition of hue H is set to 6≦H≦8 in this case, and skin color can be specified.

(Formula 1)

V = _max (R, G, B)...(1-1)

S＝(V-X)/V ...(1-2)

where X = _min (R, G, B).

(Formula 2)

When R=V, H=(pi/3)*(b-g)...(2-1)

When G=V, H=(pi/3)*(2+r-b)...(2-2)

When B=V, H=(pi/3)*(4+g-r)...(2-3)

where r=(V-R)/(V-X),

g=(V-G)/(V-X), and

b=(V-B)/(V-X).

When it is judged that the current frame (n) data is included in the skin color or a color range close to the skin color specified by applying the above method, and the previous frame (n-1) data is included in the black level, each color level comparator 4 , 4A and 4B select the second correction mode, otherwise these comparators select the first correction mode.

Calculation example of overdrive amount (correction amount)

A calculation example of the correction amount (second correction amount) applied when preparing the second correction amount table 52 shown in FIG. 5 will be described below.

For each RGB color, the previous frame (n-1) pixel data is assumed to be 0, and the current frame (n) pixel data is assumed to be 192 for R, 160 for G, and 64 for B. In this case, the respective first correction amounts in RGB become +37 (=229-192) for Lr1, +40 (=200-160) for Lg1, and +26 (=90-64) for Lb1. The respective differential correction amounts ΔLr, ΔLg, and ΔLb of RGB are prepared, for example, by the following method under the condition that when an image is displayed with the corrected RGB data, the transition time of the signal level in the liquid crystal display panel is within a certain range. frame display period.

In the first method, as shown in FIG. 7A , the overdrive amount (first correction amount) of blue having the longest response time is increased.

The differential correction amount ΔLb, which is an amount to be increased, is prepared by a predetermined formula such as (R-B)/b, where b is an appropriate integer of 2 or more. When this formula is applied, for example, assuming that b is 4, R is 192, and B is 64, then the B differential correction amount ΔLb=(192−64)/4=+32. In FIG. 4, the result "32" is added to the first R correction amount Lr1 having a value of +26 by the B adder-subtractor 6b. Therefore, the second B correction amount Lb2 becomes 58 (=26+32).

Therefore, the liquid crystal optical response of the B pixel in the pixel triplet is increased, so the amount of the red component is relatively reduced, so the red persistence of the image is not obvious. In this case, the differential correction amounts ΔLg and ΔLb for green and red can be set to some positive value by applying other appropriate formulas for color balance of skin color such as buff.

The B differential correction amount ΔLb is prepared in the same manner with colors other than the colors R=192, G=160, B=64 in FIG. 3, and if necessary, the differential correction amounts of R and G are also prepared. In this case, the value of b may be appropriately changed. Note that when the value of the formula (R-B)/b becomes negative, it is fixed to 0.

Thus, the formation of the differential correction amount table 50 shown in FIG. 4 is completed. The second correction amount table 52 shown in FIG. 5 is prepared by adding the first correction amount to the prepared differential correction amount.

In the second method, as shown in FIG. 7B , unlike the first method, the amount of overdrive for the apparent color red is reduced.

The R differential correction amount ΔLr is prepared by a predetermined formula such as (R-B)/b, where b is an appropriate integer of 2 or more. In the second method, the R difference correction amount ΔLr is subtracted from the first R correction amount Lr1 by the R adder-subtractor 6r shown in FIG. 4 .

Note that, in the same manner as the first method, other differential correction amounts such as ΔLg and ΔLb may be set to certain values, which are subtracted from the respective first correction amounts, in consideration of color balance. In the blue pixel having the lowest response, under the condition that the optical response of the liquid crystal is completed within one frame display period, if the condition is not satisfied, the differential correction amount may be set to 0 which does not change the first correction amount, Otherwise the differential correction amount may be added to the first correction amount.

The third method is applied by combining the first method and the second method.

Since the overdrive amount is controlled based on color information detection, in image information of skin color frequently displayed in television images, redness persistence of an image generated in motion of an image including, for example, human skin color such as buff can be reduced .

Specifically, when increasing the overdrive amount of blue, the overdrive amount is increased only when necessary (that is, if the red persistence of the image can be reduced (second correction mode)), otherwise in other cases, the overdrive amount is increased. The overdrive control in the prior art is applied (first correction mode). Therefore, image quality is improved.

When reducing the overdrive amount of red, the overdrive amount is only reduced when necessary (i.e. if the red persistence of the image can be reduced (second correction mode)), otherwise in other cases, the prior art Overdrive control is applied (first correction mode). Therefore, image quality is improved.

In the above description, all the processes shown in FIGS. Addition and subtraction to generate new pixel data) are performed in units of pixel triplets of the three primary colors.

Note that this unit is preferably pixel data of each color of the three primary colors averaged in an area including a plurality of pixel triplets located around the pixel triplet to be corrected.

Figure 8 shows an area of 3x3 pixel triplets defined as the area of pixels to be averaged. Averaging processing is performed in advance by an unshown CPU.

In the above-described manner, the averaged pixel data of each RGB color is applied to the determination of skin color, so noise components can be suppressed and false detection can be avoided. A benefit can thus be gained in terms of improved accuracy of skin color detection.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made depending on design requirements and other factors within the scope of the appended claims or the equivalents thereof.

Cross References to Related Applications

The present invention contains subject matter related to Japanese Patent Application No. 2005-161688 filed with the Japan Patent Office on June 1, 2005 and Japanese Patent Application No. 2006-82617 filed with the Japan Patent Office on March 24, 2006, both of which The entire content of is incorporated herein by reference.

Claims (12)

1. a processing will be transfused to the image processing apparatus of the image of liquid crystal display device, comprising:

Frame memory is used for storing the signal at preceding image of former frame, and

Correction processing unit, described correction processing unit be configured to receive described at preceding image signal and the signal of present image as input, and the signal rank of proofreading and correct described present image based on described signal rank difference between preceding image and described present image

Wherein said correction processing unit by use following both one of carry out described correction:

First correction mode, wherein said at preceding image the signal rank and the relation between other correcting value of signal level of described present image be identical for the various colors in the three primary colors, and

Second correction mode, be used for input picture from described when preceding image transform is described present image, proofread and correct the present image of at least a color in the three primary colors by using second correcting value different, to finish the optic response of described liquid crystal display device in whole primary colours in the display cycle at a frame with first correcting value of described first correction mode.

2. image processing apparatus as claimed in claim 1, wherein for every kind in three primary colors color, described correction processing unit comprises the image transitions table, described image transitions table is configured to receive described signal at preceding image and described present image as input, specify signal rank after the correction of described present image by described first correction mode or described second correction mode being applied to the signal rank of being imported at the signal rank of preceding image and the present image imported, and the output result.

3. image processing apparatus as claimed in claim 1, wherein said correction processing unit comprises the levels of color comparing unit, described levels of color comparing unit is configured to receive described signal at preceding image and described present image as input, the signal rank of being imported at every kind in three primary colors color comparison at preceding image and the present image imported, and the result selects one of described first correction mode and described second correction mode based on the comparison.

4. image processing apparatus as claimed in claim 3, wherein said correction processing unit also comprises

The first image transitions table, the described first image transitions table is configured at every kind of color, the present image that to import in selected described first correction mode is converted to the present image that its signal rank is corrected based on signal rank relation identical for three primary colors, and the output result, and

The second image transitions table, the described second image transitions table is configured at every kind of color, the present image that to import in selected described second correction mode is converted to its signal rank and uses the present image that described second correcting value is corrected in by at least a color in three primary colors, and the output result.

5. image processing apparatus as claimed in claim 3, wherein said correction processing unit comprises

First proofreaies and correct scale, described first proofreaies and correct scale is configured to keep first correcting value at every kind of color, the signal that receives described present image in selected described first correction mode is as input, and at signal rank corresponding first correcting value of every kind of color output with the present image of being imported;

The difference correction scale, for at least a color in the three primary colors, described difference correction scale is configured to keep poor between described first correcting value and described second correcting value at every kind of color, and in selected described second correction mode, output is based on the comparative result of described levels of color comparing unit and the color difference of appointment;

Adder-subtractor, for at least a color in the three primary colors, described adder-subtractor is configured at every kind of color, to be added to from described first from the difference of described difference correction scale output and proofread and correct described first correcting value of scale output, or deduct poor from described difference correction scale output, and export described second correcting value from described first described first correcting value of proofreading and correct scale output; And

Adder, described adder is configured to receive the signal of described present image as input, to proofread and correct described first correcting value of scale output or be added to the signal of the present image of being imported from described first at every kind of color, and export signal after the correction of described present image from described second correcting value of described adder-subtractor output.

6. image processing apparatus as claimed in claim 3, wherein said correction processing unit comprises

First proofreaies and correct scale, described first proofreaies and correct scale is configured to keep first correcting value at every kind of color, the signal that receives described present image in selected described first correction mode is as input, and at signal rank corresponding first correcting value of every kind of color output with the present image of being imported;

Second proofreaies and correct scale, and at least a color in the three primary colors, described second proofreaies and correct scale is configured to keep second correcting value at every kind of color, and exports second correcting value at every kind of color in selected described second correction mode;

Switch, described switch is configured to the comparative result based on described levels of color comparing unit, selects described first to proofread and correct one of scale and described second correction scale; And

Adder, described adder is configured to receive the signal of described present image as input, add based on the selection result of described switch and described first correcting value or described second correcting value imported at every kind of color, and export signal after the correction of described present image.

7. image processing apparatus as claimed in claim 3, wherein said levels of color comparing unit is the signal rank of the adjacent a plurality of pixels in unit at the pixel triplets with three primary colors in every kind of average described liquid crystal display device of color, and comes at every kind of more described signal rank of color by the signal rank after using on average.

8. image processing apparatus as claimed in claim 1, wherein said correction processing unit comprises that correcting value generates parts, described correcting value generates in described first correcting value in certain grey level range that parts are configured to keep off and on image and described second correcting value part of each, and generates the correcting value that does not keep by interpolation from the correcting value that is kept.

9. liquid crystal indicator comprises:

Liquid crystal display device is used for display image;

Frame memory is used for storing the signal at preceding image of former frame, and

Correction processing unit, described correction processing unit be configured to receive described at preceding image signal and the signal of present image as input, the signal rank of proofreading and correct described present image based on described signal rank difference between preceding image and described present image, and the signal after will proofreading and correct outputs to described liquid crystal display device

Wherein said correction processing unit by use following both one of carry out described correction:

First correction mode, wherein said at preceding image the signal rank and the relation between other correcting value of signal level of described present image be identical for the various colors in the three primary colors, and

Second correction mode, be used for input picture from described when preceding image transform is described present image, proofread and correct the present image of at least a color in the three primary colors by using second correcting value different, to finish the optic response of described liquid crystal display device in whole primary colours in the display cycle at a frame with first correcting value of described first correction mode.

10. liquid crystal indicator as claimed in claim 9, wherein said correction processing unit comprises the image transitions table, described image transitions table is configured to receive described signal at preceding image and described present image as input, specify signal rank after the correction of described present image by described first correction mode or described second correction mode being applied to the signal rank of being imported at the signal rank of preceding image and the present image imported, and at every kind in three primary colors color output result.

11. liquid crystal indicator as claimed in claim 9, wherein said correction processing unit comprises the levels of color comparing unit, described levels of color comparing unit is configured to receive described signal at preceding image and described present image as input, the signal rank of being imported at every kind in three primary colors color comparison at preceding image and the present image imported, and the result selects one of described first correction mode and described second correction mode based on the comparison.

12. a color correcting method that is used for the image that will be transfused to is carried out colour correction may further comprise the steps:

At the described image that will be transfused to of each frame delay, and

After ruling out the image section that is transformed to the predetermined color that will be corrected in the image based on the signal rank difference between the preceding image and the present image that will be transfused to and not be delayed that after delay, will be transfused to, proofread and correct color in the image section that is transformed to the described color that will be corrected in the described present image by first correction mode being switched to second correction mode, wherein in described first correction mode, relation between other correcting value of signal level of described signal rank at preceding image and described present image is identical for the various colors in the three primary colors, and described second correction mode is used second correcting value different with first correcting value of described first correction mode at least a color of three primary colors.

Images