TWI420491B - Adaptive feedback control method for field sequential lcd - Google Patents

Description

Adaptive feedback control method for color sequential display

The invention relates to image display, in particular to an adaptive feedback control method for improving the color separation phenomenon of a color sequential display by adjusting a backlight color field which is obtained by instantly adjusting the minimum color difference of the image according to the screen content.

Conventional liquid crystal displays use a color filter to achieve full color, but the resulting light efficiency is not as expected. Recently developed fast-reaction liquid crystals, such as the Optically Compensated Bend (OCB) mode, and backlight sources, such as the high-efficiency Light-Emitting Diode (LED), have implemented the color-sequence method (Field). Sequential Color (FSC) mechanism of liquid crystal display (LCD). By sequentially displaying the main red, blue, and green fields faster than the time resolution of the human eye response, full color effects can be achieved without the use of color filters. In combination with a backlight of a light-emitting diode and a liquid crystal panel of an optically compensated curved alignment mode, it is expected that a color sequential liquid crystal display (FSC-LCD) can be a color liquid crystal display with high light efficiency, low power consumption, and low material cost.

However, the most common problem with color-sequence liquid crystal displays is the problem of Color Break-Up (CBU). The color separation CBU is caused by the relative movement between the object in the image and the observer's eye, that is, during the human eye saccade, the saccadic suppression suppresses the human eye to the brain. signal of. Please refer to FIG. 1 , which shows a color separated image simulated by an RGB color sequence method. In the color separation image M1 simulated by the three primary color subfields R, G, and B, the color separation phenomenon can be perceived to cause the entire image to be reduced. quality. Referring to FIG. 2 again, it is a schematic diagram showing a conventional color-sequence color image display method. Under the condition that the observation point moves with time, the color separation phenomenon can be seen by the color-coded color display pattern. In the color-sequence color display, images are displayed in time order, and the color order is "RGB RGB RGB...", where R represents a red sub-picture, G represents a green sub-picture, and B represents a blue sub-picture. Taking the white image W10 as an example, when a white image is required to appear, the white image W10 seen from the moving observation point will appear blue B and blue B and green at one edge W11 (left side of FIG. 2) of the white image W10. The combination of G, and at the other edge W12 (on the right side of Fig. 2), presents a combination of red R and red R and green G, which is the so-called color separation phenomenon.

In the application of the color-sequence method, U.S. Patent No. 5,337,068 discloses a color-sequential display system and a method for forming an image, in which a liquid crystal device is combined with backlights of three colors of red, blue and green, and backlights of three colors respectively emit light, and then The liquid crystal device separately adjusts the amount of passing light to form a sub-picture of three colors, and finally forms a color picture by sub-pictures of three colors of red, blue and green. The color separation method produced by the conventional color-sequence system architecture and the image forming method is obvious and more easily perceived.

U.S. Patent No. 6,570,554 discloses a liquid crystal display that uses a sub-color field that regularly transforms three consecutive frames to solve the color separation problem of a conventional color sequential liquid crystal display; when the human eye traces moving objects at the same speed The integration result of three consecutive images is on the retina of the human eye and does not exhibit excellent separation. However, in this method, when the green color field frequency is lower than 50 Hz, the human eye will perceive the flicker phenomenon (Flicker), resulting in poor picture quality.

Furthermore, U.S. Patent No. 7,057,668 discloses an image signal processing method for solving color separation color separation phenomenon, using red, blue and green light-emitting diodes, or additionally adding a white light-emitting diode. Body, as a backlight display, when the image signal input is converted to YCrCb color system; when the display content knows the color separation phenomenon is slight, the color sequence method is used to display the image frame; and when the display content color separation phenomenon is serious, then Adjusted to change the backlight to full-bright white light, that is, the red, blue, and green three-color light-emitting diodes are simultaneously illuminated, or only the white light-emitting diodes are turned on to suppress the occurrence of color separation. However, when the backlight is fully lit, a color filter is still needed to achieve the full color image.

In addition, Jongseo Lee et al. published an article in IMID/IDMC'06 with the theme "Noble Measurement Method for Color Breakup Artifact in FPDs", which uses CIE LUV color coordinates to analyze color separation phenomena and is defined in this coordinate. Color difference (ΔE) is an indicator for quantifying color separation; however, in the literature published here, no other new methods have been proposed for improving color separation.

In the improvement of the color separation problem, U.S. Patent No. 6,911,963 proposes a color-sequential display method to reduce the color separation, and displays the timing of the brightness information of the input image information having all display colors for display. Inputting image information, that is, changing display color and brightness information synchronously, wherein a color image is displayed in at least four subfield periods in one page period, and a picture signal in at least one subfield period is a non- a non-primary color picture signal, and the non-primary color picture signal is generated by at least two primary color signals in an input picture signal including a primary color signal; and the processing method is to first image The gray scale rgb is converted into a graph of the tristimulus value XYZ of the CIE1931XYZ color system, and then converted into a corresponding backlight color stimulus value XYZs, thereby determining the additional subfield color.

When using the above method, you must first preset three conditions, including:

(1) Color separation is likely to occur at a high frequency portion of a high luminance (Y value) signal level;

(2) color separation easily occurs when the frequency of the X value is greater than the frequency of the Z value;

(3) Color separation easily occurs in the portion of high Z value, that is, when both X value and Y value are low.

Therefore, the color selected for each signal level that satisfies the conditions (1) to (3) is the color of the additional fourth subfield. However, in order to obtain the color of the fourth subfield, it is necessary to first analyze the statistical value of the image, which not only consumes the calculation time but also increases the calculated capacity.

Based on the above problems, the inventors have proposed a new adaptive feedback control method for a color sequential display to overcome the deficiencies of the prior art.

The object of the present invention is to provide a method for synchronously updating the liquid crystal and backlight gray scale information according to the input image content, so that the color brightness originally distributed in each color field can be concentrated to a single color field, and the total of each pixel compared with the input picture is greatly reduced. The color difference is used to effectively suppress the color separation phenomenon.

In order to achieve the above object, the present invention provides an adaptive feedback control method for a color sequential display, comprising: a resetting step of converting a grayscale value of a three primary color field of an input image into a new three primary color field and a primary color a grayscale value of a field (D-field); a sampling step of performing pixel sampling of a sampling interval for the resolution of the input image; and a feedback control step of separating the color value by one color in the Lu'v' color space and The input image color value is subjected to pixel-to-pixel addition of each color separation to obtain a total color difference value, and the total color difference value is subjected to one-digit precision feedback control to obtain a The minimum summed color difference value; and the liquid crystal/backlight synchronization step, according to the minimum summed color difference value, synchronizing a liquid crystal signal and a backlight information of the input image.

Preferably, the sampling interval is a range of 2×4 pixels to pixels.

Preferably, the summed color difference Δ E _sum is expressed as follows:

Among them, Lu'v' _CBU and Lu'v' ₀ represent the color separation color value and the input image color value in the Lu'v' color space, respectively.

Preferably, the bit number accuracy is 3-bit precision.

Preferably, the new grayscale values r', g', b' and d in the resetting step are expressed by the following equation:

r' = T ^-1 ( T ( r )- T ( d ) × BL _r );

g' = T ^-1 ( T ( g )- T ( d ) × BL _g );

b' = T ^-1 ( T ( b )- T ( d ) × BL _b );

Where T ( i ) represents the transfer function from the gray level i to the liquid crystal conversion value, and T ^-1 is the inverse function.

Preferably, the interval produces eight sets of color separation plus total color difference values (CBU Δ E _sum ).

In addition, the present invention provides an adaptive feedback control method for a color sequential display, comprising: applying to an original image of an input image divided into a plurality of blocks, comprising: a sampling step, sampling the original image, Obtaining a sampling pattern having a resolution smaller than the original image; and performing a resetting step of converting the liquid crystal signal of the three primary color fields of the input image into a new three primary color field and a corresponding backlight signal of a D-field liquid crystal signal And the feedback operation step includes: a time delay step of delaying the new three primary color field liquid crystal signals by different times; and a subtracting step, subtracting the liquid crystal signals of the respective color fields and taking an absolute value; and adding steps to the phase The sum of the color fields in the subtraction step is added up to obtain the accumulated values of the respective blocks; wherein the sampling step, the resetting step, and the feedback operation are performed from the starting block of the blocks to the final block. In step, the accumulated value obtained by the respective block operations takes a minimum accumulated value, which is a backlight signal of the respective block, and is provided to the next block for operation.

While the invention has been described in terms of several preferred embodiments, the preferred embodiments of the present invention It is not intended that the invention be limited to the following drawings and embodiments.

Hereinafter, embodiments of the method of the present invention will be specifically described.

In order to specifically suppress color separation, the three primary color subfields R, G, and B are concentrated in a dominant color field (D-field) D as shown in FIG. By resetting the color fields, the intensity of the primary colors can be increased, and the apparent primary color field can be concentrated into a single mixed color field to form an image M2 that can suppress color separation. Thus, the present invention has less color separation and less color separation visibility than conventional three primary color fields.

Please refer to FIG. 4, which is a block diagram showing the feedback control method of the present invention. In order to achieve the above-mentioned effects, the present invention provides a feedback decision algorithm for determining a color field (D-field) color and a liquid crystal/backlight signal to conform to practical applications. The present invention includes a sampling step S1, a reset step S2, and a back The control step S3 is performed, and finally, the liquid crystal/backlight synchronization step S4 is performed, and the optimum backlight value can be effectively obtained to reduce the influence of color separation.

Sampling Step (S1):

In the resolution of the input image, the complexity of the operation is determined. Therefore, it is necessary to compare the selected sampling intervals, and in the sampling range of 1×2 to 4×8 pixels, the comparison can reduce the calculation amount without affecting the image. Resolution.

Please refer to FIG. 5, which is a diagram showing the relationship between the comparison error rate and the image sampling interval. The 2 × 2 sampling period in the figure is four sub-images with 1/4 resolution, and so on. If the four sub-images can replace the original image by Δ E _sum operation, then four different backlight states can be matched at the same time, and the step of approaching the minimum Δ E _sum is shortened. When the minimum Δ E _sum of the three primary colors RGB backlight states of the sub-image and the original image are not equal, the sub-image is considered to be an error.

In order to calculate the Δ E _sum in the subsequent feedback control step S3, the amount of calculation can be reduced in practical applications, and the color backlight optimization must be simplified in the main color field (D-field). The comparative image of Fig. 5 uses the five images (Tiffany, Space Robot, Airplane, Baboon, and Lena, not shown) used in Fig. 6 to perform the correlation between the sub-image and the error rate. The error rate is defined as the ratio of the number of errors to all sub-images. As can be seen in the figure, there is no error in the sampling interval of less than 2 × 4 pixels in the five images. Accordingly, by determining the minimum of Δ E _sum, selecting a sampling interval of 2 × 4, to simultaneously provide the three primary colors RGB backlight 8 groups.

Reset step (S2):

The reset of the main color and ternary color (DRGB) color sequence liquid crystal/backlight gray scale is determined by the image content. In the main color field (D-field), the grayscale values of the three primary color backlights are represented by BL _r , BL _g , BL _b , respectively. The relationship between the gray scale and the light intensity (γ curve) is a linear relationship. According to the backlight information, a new liquid crystal gray scale value r' is formed in the three primary color fields - red (red), green (green), blue (blue, b) and the main color field (D-field, d). , g', b' and d, are expressed by the following formula:

Formula (1): r' = T ^-1 ( T ( r )- T ( d ) × BL _r );

Formula (2): g' = T ^-1 ( T ( g )- T ( d ) × BL _g );

Formula (3): b' = T ^-1 ( T ( b )- T ( d ) × BL _b );

Where T ( i ) represents a transfer function from gray scale i to a liquid crystal conversion value (LC), and T ^-1 is an inverse function. The gamma curve between the grayscale value and the converted value less than one is used to maintain white balance.

Feedback control step (Feedback Control Step, S3):

The decision of the primary color field (D-field) color backlight is very important to reduce color separation. As shown in FIG. 7, it is an analog color separation image of the test image of the main color field in three different backlight gray scale states. The simulated color separation image can be composed of four different panning color images. The software used for its simulation is MATLAB. 7A shows a color separation image (referred to as a KRGB color field) having a zero-RGB value in a conventional main color field. In other words, this image is obtained by a conventional three-primary field driving method. Conversely, as shown in FIG. 7B, it is conventional to provide a maximum RGB value in the primary color field to display an image produced by white (referred to as a WRGB color field).

As shown in FIG. 7C, the main color field (D-field) of the present invention adds up the image generated by the color difference between the color separation and the original image (referred to as the DRGB color field), and the sum is The pixels by pixel are summed by the pixels of the color separation, and the total color difference Δ E _sum is expressed as follows:

Among them, Lu'v' _CBU and Lu'v' ₀ are the color separation (CBU) color values and the original image color values in the Lu'v' color space, respectively. The color backlight determines the distribution of brightness in the color field image. When the main brightness intensity is concentrated in the main color field (D-field), the color of the three primary color fields will disappear, and thus there will be less color separation. It can be found that in the three images of FIG. 7, the color separation phenomenon of the image generated by Δ E _{sum of} the DRGB color field is smaller than that of the image generated by the other two color fields (KRGB and WRGB), that is, the image is reduced. The phenomenon of color separation.

In the practical application of the Δ E _sum calculation, simplification of the color backlight gray scale value optimization on the main color field (D-field) is necessary. The more bits of the backlight, the more accurate the minimum Δ E _sum can be included, as shown in Figure 6. However, increasing the accuracy of the backlight increases the calculated load at an exponential rate. Please refer to FIG. 6 , which is a graph showing the relationship between the number of backlight bits and the sum of the color difference values Δ E _{sum of the} five test images. Compared with the accuracy of 1 bit, when the number of bits is greater than 3, the Δ E _{sum of the} five test images has reached saturation. Therefore, the accuracy of the 3-bit is set to the modified factor of the RGB backlight of the three primary colors, that is, the feedback control of the 3-bit backlight is used to obtain the best accuracy, and the calculation can be reduced. the amount.

After the above three steps are performed, that is, the reset step S2 of calculating Δ E _sum is performed, and the sampling step of the 2×4 sampling interval and the feedback control step S3 of the 3-bit precision are obtained to obtain the minimum Δ E _sum Finally, the liquid crystal/backlight synchronization step S4 for determining the backlight is performed, and the synchronization step can be time delayed by the buffer to achieve the synchronization effect between the liquid crystal and the backlight. Therefore, when the color backlight generated by the method of the main color field (D-field) is optimized, the color separation phenomenon can be effectively reduced; moreover, the color separation effect can be obtained by the Δ E _sum value. Decide.

Please refer to FIG. 8A and FIG. 8B simultaneously, which are respectively a detailed flowchart for determining the gray scale of the liquid crystal and the color backlight, and a schematic diagram of obtaining the final backlight value by approximating the 3-bit precision. This embodiment includes a step of acquiring a total color difference value and a signal synchronization step, which will be described below in a more detailed embodiment.

The step of obtaining the total color difference value includes: step SA1: converting the image of the nth page to the Lu'v' color space; step SA2: performing sampling of 8 sets of 1-bit backlights and sub-images in the 2×4 sampling interval, to contain the color separation image, and compared to the original input image, synchronizing 8CBU-Δ E _sum (8 group color separation Δ E _sum) calculation; step SA3: screening decision bit of the next page to be Δ E _sum The number of elements; step SA4: a group of new 2-bit groups of color backlights adjacent to a group of 1 bit group having two minimum Δ E _sums , regarded as the smallest Δ E _sum ; wherein the screening condition N of step SA3 is as follows :

And all of the eight sets of color backlights in step SA4 are used in step SA2 by passing through a backlight buffer (BL buffer), which is a signal register for synchronizing between the liquid crystal and the backlight. (signal register).

In another part of FIG. 8A, the signal synchronization step is to synchronize the liquid crystal signal with the backlight signal, as follows: Step SB1: Pass the liquid crystal signal of the input image through the frame buffer to obtain the n-th. a liquid crystal page signal; step SB2: the minimum CBU-Δ E _sum backlight passes through the color buffer backlight (BL buffer), to obtain the grayscale values of the backlight n-1 th page; step SB3: via a look-up table (the lookup Table, LUT), to make the liquid crystal signal and the backlight grayscale value of the n-1th page synchronized, and generate a new liquid crystal grayscale value.

In FIG. 8B, the solid dots of the 1-bit and 2-bit groups represent the two smallest Δ E _sum (BL1 and BL2) groups, while the open circles represent other larger Δ E _sum groups. If any of the group 2 yuan Δ E _sum is equal to or less than 1 yuan Δ E _sum by the group, i.e., the three yuan approximation in step SA3 in group 3 yuan. Conversely, if all Δ E _sum by 2 yuan groups Δ E _sum is greater than 1 yuan group, Group 1 8-bit color backlights if the next page is calculated CBU-Δ E _sum of. The pixel accuracy of the color backlight is controlled by a feedback that determines the backlight optimization.

Therefore, by the above-described feedback control method, it is possible to reduce the color separation phenomenon to minimize the generation of color separation, or to control it, thereby reducing the load of the calculation amount.

The above method (DRGB color field) performs the reset step S2 in units of a single screen (please refer to FIG. 4), and the color gamut conversion must be performed first, and the calculation time required is long, so that the calculation time is further shortened. The color gamut conversion is not required, and is divided into a plurality of display blocks on a single screen, and then the resetting step S2 is performed for each display block to reduce the color separation phenomenon to minimize the color separation, and the detailed steps are as follows. Rear.

Please refer to FIG. 9, which is a block diagram showing another embodiment of the present invention in a resetting step. This embodiment (Fast DRGB color field) divides a single picture P into three blocks (Block) for description, that is, the first block B1, the second block B2, and the third block B3, but this is not The step of each block includes: a sampling step S5, a resetting step S6, and a feedback control step S7; Represents the original LCD P ^o red, green, blue three LCD signals, x and y are graphic coordinates, Represents three liquid crystal signals of P ^s red, green and blue. Represents the four liquid crystal signals after the DRGB calculation step S6, Express versus After subtraction, the absolute value is added to the value accumulated in order, and Block represents the number of divided blocks, and number represents the number of groups of accumulated values.

Referring to FIG. 10A and FIG. 10B simultaneously, the original image and the sampled sample after sampling are respectively shown in another embodiment of the present invention. First, in the sampling step S5, it is assumed that one of the four signals is taken, so that the resolution of the sampled pattern P ^s (Fig. 10B) after sampling becomes smaller than the original picture P ^o (Fig. 10A).

In the resetting step S6, the purpose of the DRGB is to decompose three liquid crystal signals, which are originally three red, green and blue, into four liquid crystal signals. The new three red, green and blue LCD signals will be red, green and blue, and the fourth main color field (D-field) d liquid crystal signal will be reflected in a mixed red, green, Blue three backlight signals, the main color field d liquid crystal signal will represent the information of the whole picture, so the new three red, green and blue liquid crystal signals will become smaller, so that the color separation suppression can have better results.

Please refer to FIG. 11A, FIG. 11B and FIG. 11C, which are schematic diagrams showing sampling steps of the first block, the second block and the third block in another embodiment of the present invention. The selection criterion of the backlight signal is to concentrate most of the information in the main color field d, so the brightness of the main color field d is not too low, so the backlight grayscale value starts from 128 to 255, and is equally divided into five equal parts, 128. The backlight grayscale values of 160, 192, 224, and 255 are followed by red, blue, and green backlights, and there are 125 backlight groups. The 125 backlight groups are represented by 125 small cubes (as shown in Fig. 11A), and then the eight small cubes at the outermost edge are taken out, that is, eight sets of backlights are selected, and the eight sets of backlight values are (128, 128, 128), (128, 128, 255), (128, 255, 128), (128, 255, 255), (255, 128, 128), (255, 128, 255), (255, 255, 128) , (255, 255, 255), is a combination of 128 and 255 values; after that, the liquid crystal signal of the first block B1 is substituted into the image signal decomposition formula according to the backlight values of the eight groups (equations (1) to (4) The liquid crystal signal of the main color field d is calculated, and the new liquid crystal signals of r', g', and b' are sequentially reversed.

Please refer to FIG. 12, which is a schematic diagram showing the time delay of each signal in the feedback operation step according to another embodiment of the present invention. In the feedback control step S7, the new r', g', b' liquid crystal signals are delayed by different times (time delay step, step S71), for example, r' is delayed by one clock (Clock), g' is delayed by two. Clock, b' delay three clocks, the main color field d liquid crystal signal is not delayed (as shown in Figure 12), of course, can also delay r' two clocks, g' delay one clock, b' delay two The clock, the main color field d liquid crystal signal delays three clocks, etc., is not limited to this; because it is assumed that the main color field d is the first display, and the meaning of r', g', b' delay is Represents the signal of the analog color separation. Finally, in sequence, the liquid crystal signals of the respective color fields are subtracted and taken as absolute values (subtracting step, step S72), that is, K _n =| T _R' - T _R |+| T _G' - T _G |+ | T _B' - T _B | + K _{n -1} , and then sum total (addition step, step S73), that is, The accumulated value K ₁ ~K _{8 of the} first block B1 is obtained.

The minimum accumulated value K is obtained, and the corresponding backlight signal group is (128, 128, 128) as the backlight signal of the first block B1, that is, the new backlight signal is formed in the first block B1. The image is relatively suppressed from color separation and supplied to the resetting step S6 of the second block B2 for processing.

Referring to FIG. 9B again, since the processing of the feedback method of the present invention has been performed in the first block B1, the original 125 sets of backlights (small solid squares in FIG. 11A) are converged toward the cube of (128, 128, 128). 27 backlight groups are formed, the new backlight gray scale values are 128, 160, 192, and then the outermost eight points of the 27 backlight groups are taken out, and the backlight groups are sequentially (128, 128, 128), (128, 128, 192), (128, 192, 128), (128, 192, 192), (192, 128, 128), (192, 128, 192), (192, 192, 128), (192, 192, 192) Then, the DRGB calculation step S6 and the feedback operation step S7 are performed to obtain the accumulated value K ₁ to K _{8 of the} second block B2, and the obtained minimum accumulated value K is used as the backlight signal of the second block B2.

Similarly, the third block B3 is also processed according to the method of the first block B1 and the second block B2, and the 27 sets of backlights are converged to 8 sets of backlights, and the smallest accumulated value is obtained, which is regarded as the third block B3. The best backlight signal.

In summary, in the first embodiment (DRGB color field), the image picture is divided into two sub-pictures in each block by using a 2×4 sampling period, given that each sub-picture is different. Backlight color field, so each different backlight color field, according to the image signal decomposition formula, can get a new different sub-picture, and then the new sub-picture is simulated color separation, and the original picture signal is the difference The sum is accumulated. After three approximations through the same mode, each backlight will select a different backlight color field. Finally, the sum of the differences is the best backlight color field. In the calculation, the 3-bit accuracy is used to approach the optimal solution by means of feedback. From the best backlight color field grayscales BLr, BLg, and BLb, the corresponding main color field liquid crystal gray scale d can be obtained. At the same time, since the component of the luminance has been moved to the main color field d, the corrected r', g', b' needs to be deducted from the contribution of the main color field d, and the process of synchronizing the backlight with the liquid crystal signal is also considered.

In the second embodiment (Fast DRGB color field), the original image and the color separation map newly formed according to different backlights are directly used, and the difference sum is directly compared to be compared, so the calculation is more rapid; reuse Multi-block, here assumes 3 blocks as an example. When the image is sent to the first block according to the signal, the sample is then sampled and the different backlight color fields are used to make the difference between the image and the color separated image, and the minimum difference is obtained. The sum of the values is the best backlit color field of the first block image, and the best backlight color of the second block image is obtained by taking the first best backlight color field into the second block image. The field, after approximating through the third block, yields the final best backlight color field. Because the operation is based on the input image, you can do real-time calculations, you don't need an image buffer, and you can get the best backlight color field when the entire image is input.

According to FIG. 9A and FIG. 9B, the previous block affects the next block, but the other blocks can be processed in parallel by means of the control signal writing, and then by each block. Convergence to select the small total color difference of each block, so that each block has its own independent optimal backlight signal; thus, in terms of appearance, the same effect can be achieved with the foregoing method.

In addition, in order to make the image of the main color field d of the invention more power-saving, the backlight signals of the red, green and blue liquid crystal signals r, g, b can be simultaneously DIMMING, according to the following new The liquid crystal signal decomposition formula (formula (6)~(9)) differs from the original formula (formulas (1) to (4)) in that the red, green, and blue backlight signals r, g, and b are based on The backlight is adjusted, and the original formula (Eqs. (1) to (4)) treats the backlights of the red, green, and blue backlight signals r, g, and b as fully lit.

This embodiment (Fast DRGB color field) does not use the entire image to perform the operation, but is divided into several blocks, so there is no phenomenon that the color is concentrated in a certain block, and the two implementations of the present invention are used. The methods (DRGB and Fast DRGB) compare the relative color separations, and it can be seen that there will be similar color separation improvement (please refer to FIG. 13), so it can be explained that the two implementation methods mentioned in the present invention have the same color separation improvement. result.

Although the present invention has been explained in connection with the preferred embodiments, it is not intended to limit the invention. It should be noted that many other similar embodiments can be constructed in accordance with the teachings of the present invention, which are within the scope of the present invention.

B1. . . First block

B2. . . Second block

B3. . . Third block

M1. . . Color separation image

M2. . . Suppressed color separation image

W10. . . White image

W11. . . edge

W12. . . edge

S1~S4. . . Steps of adaptive feedback control method according to an embodiment (DRGB) of the present invention

SA1~SA4. . . Get the total color difference step

SB1~SB3. . . Signal synchronization step

S5~S7. . . Steps of adaptive feedback control method according to another embodiment (Fast DRGB) of the present invention

S71~S73. . . Substeps of the feedback operation step

Figure 1 shows a one-color separated image simulated by an RGB color sequence method.

2 is a schematic view showing a conventional color sequential color image display method.

Fig. 3 is a view showing a one-color separated image simulated by the D-field color sequential method of the present invention.

Figure 4 is a block diagram showing the feedback control method of the present invention.

Figure 5 is a graph showing the relationship between the comparison error rate and the image sampling interval.

Figure 6 is a graph showing the relationship between the number of backlight bits and the total color difference Δ E _sum accuracy for five test images.

Fig. 7A shows a color separation image (referred to as a KRGB color field) having a conventional primary color field having a zero-RGB value.

Figure 7B shows an image produced by the conventional color field providing a maximum RGB value to display white (referred to as WRGB color field).

Fig. 7C shows an image produced by the present invention in which the color difference (referred to as the DRGB color field) between the color separation and the original image is added.

Fig. 8A is a detailed flow chart showing the gray scale of the liquid crystal and the color backlight.

Figure 8B is a schematic diagram showing the final backlight value obtained by approximating the 3-bit accuracy.

Figure 9 is a block diagram showing another embodiment of the present invention in a resetting step.

Figure 10A is a view showing the original image before the sampling step of another embodiment of the present invention.

Figure 10B is a sampling diagram showing sampling after sampling steps in another embodiment of the present invention.

Figure 11A is a diagram showing the sampling of the resetting step of the first block in another embodiment of the present invention.

Figure 11B is a schematic diagram showing the sampling of the resetting step of the second block in another embodiment of the present invention.

Figure 11C is a schematic diagram showing the sampling of the resetting step of the third block in another embodiment of the present invention.

Figure 12 is a diagram showing the time delay of each signal in the feedback operation step in another embodiment of the present invention.

Figure 13 is a graph showing the color separation suppression curves of the second embodiment (DRGB and Fast DRGB) of the present invention.

S1. . . Sampling step

S2. . . Reset step

S3. . . Feedback control step

S4. . . LCD/backlight synchronization step

Claims (11)

A adaptive feedback control method for a color sequential display comprises: a resetting step of converting a grayscale value of a three primary color field of an input image into a new three primary color field and a grayscale of a primary color field (D-field) a sampling step of performing pixel sampling of a sampling interval for the resolution of the input image; and a feedback control step for separating the color values and color values of the input image by one color in the Lu'v' color space The pixels are summed up to obtain a total color difference value, and the total color difference value is subjected to one-digit precision feedback control to obtain a minimum summed color difference value; The liquid crystal/backlight synchronization step synchronizes a liquid crystal signal and a backlight gray scale of the input image according to the minimum summed color difference value; wherein the total color difference value Δ E _sum is expressed as follows: , where Lu'v' _CBU and Lu'v' ₀ are respectively representing the color separation color value and the input image color value in the Lu'v' color space. The adaptive feedback control method according to claim 1, wherein the sampling interval is a section of 2×4 pixels versus pixels. The adaptive feedback control method according to claim 1, wherein the bit number accuracy is 3-bit precision. The adaptive feedback control method according to claim 1, wherein the new grayscale values r', g', b', and d in the resetting step are expressed by the following formula: r' = T ^-1 ( T ( r )- T ( d ) × BL _r ); g' = T ^-1 ( T ( g )- T ( d ) × BL _g ); b' = T ^-1 ( T ( b )- T ( d )× BL _b ); Where T ( i ) represents the transfer function from the gray scale i to the liquid crystal conversion value, and T ^-1 is the inverse function, and BL _r , BL _g , BL _b are the gray scales of the backlights of the red, green and blue primary colors respectively. value. The patentable scope of the application based on the adaptability of the item 2 of the feedback control method, wherein the line section 8 generates a color separation set value plus total color difference (CBU- △ E _sum). An adaptive feedback control method for a color sequential display includes a step of acquiring a total color difference value and a signal synchronization step, wherein the step of acquiring a total color difference value comprises: placing an nth page The image is converted to the Lu'v' color space; 8 sets of 1-bit backlights and sub-images are sampled in a 2×4 sampling interval to include color-separated images, and 8 sets of colors are synchronized compared to an input image. Separating the total color difference calculation; performing the filtering of the total color difference values and determining the number of bits of the next page; and the color backlight 7 group adjacent to the 1-bit group having the two smallest total color difference values The new 2-bit group is regarded as the smallest total color difference value; the signal synchronization step includes: passing the liquid crystal signal of the input image through a page buffer to obtain a liquid crystal signal of the n-1th page. Placing a minimum color separation of the color backlight and a total color difference value through a backlight buffer to obtain a backlight grayscale value of the n-1th page; and synchronizing the n-1th page by looking up the table The liquid crystal signal and the gray scale value of the backlight generate a new liquid crystal ash Order value. According to the adaptive feedback control method described in claim 6, wherein a screening condition N for performing screening of the total color difference values is as follows: , i is from 1 to 8; and the total color difference Δ E _sum is expressed as follows: , where Lu'v' _CBU and Lu'v' ₀ are respectively representing the color separation color value and the input image color value in the Lu'v' color space. The adaptive feedback control method according to claim 6, wherein the color backlight 7 group of the new 2-bit group adjacent to the 1-bit group having the two smallest total color difference values is regarded as In the step of minimizing the total color difference value, all of the eight sets of color backlights are used in the step of calculating eight sets of color separation plus total color difference values for synchronization by passing through a backlight buffer. It is a signal register for synchronizing between the liquid crystal signal and the backlight gray scale value. An adaptive feedback control method for a color sequential display is applicable to an original image of an input image divided into a plurality of blocks, comprising: a sampling step of sampling the original image to obtain a sampling pattern having a resolution smaller than the original image; and a resetting step of converting the liquid crystal signal of the three primary color fields of the input image into a new three primary color field and a primary color field (D) -field) the opposite backlight signal of the liquid crystal signal; and the feedback operation step includes: a time delay step, delaying the new three primary color field liquid crystal signals by different times; and a subtracting step, subtracting the liquid crystal signals of the respective color fields And taking the absolute value; the accumulating step, accumulating the sum of the color fields in the subtracting step to obtain the accumulated values of the respective blocks; wherein the sampling is performed from the starting block of the blocks to the final block. In the step, the resetting step and the feedback operation step, the accumulated value obtained by the respective block operations takes a minimum accumulated value, which is a backlight signal of the respective block, and is supplied to the next block for operation. The adaptive feedback control method according to claim 9, wherein the new grayscale values r', g', b', and d in the resetting step are expressed by the following formula: r' = T ^-1 ( T ( r )- T ( d ) × BL _r ); g' = T ^-1 ( T ( g )- T ( d ) × BL _g ); b' = T ^-1 ( T ( b )- T ( d )× BL _b ); Where T ( i ) represents the transfer function from the gray scale i to the liquid crystal conversion value, and T ^-1 is the inverse function, and BL _r , BL _g , BL _b are the gray scales of the backlights of the red, green and blue primary colors respectively. value. The adaptive feedback control method according to claim 9, wherein the new grayscale values r', g', b', and d in the resetting step are expressed by the following formula: Where T ( i ) represents the transfer function from the gray scale i to the liquid crystal conversion value, and T ^-1 is the inverse function, and BL _r , BL _g , BL _b are the gray scales of the backlights of the red, green and blue primary colors respectively. value.