TWI678109B - Image processing method and display device for local dimming - Google Patents
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Abstract
本發明提出一種區域調光的影像處理方法，包括：取得原始影像，從原始影像中取得多個行與多個列，並對原始影像執行區域調光補償程序以取得補償後影像；對於每一行與每一列上的像素，判斷是否符合顏色條件與差異條件；在每一行與每一列中，計算符合顏色條件與差異條件的像素中的最大連續漸層長度，並判斷此最大連續漸層長度是否大於長度臨界值；根據有幾個行與列所對應的最大連續漸層長度是大於長度臨界值來計算出混和權重；以及根據混和權重來混和原始影像與補償後影像。 The invention provides an image processing method for area dimming, which includes: obtaining an original image, obtaining multiple rows and columns from the original image, and performing an area dimming compensation procedure on the original image to obtain a compensated image; for each row With the pixels on each column, determine whether it meets the color and difference conditions; in each row and each column, calculate the maximum continuous gradient length of the pixels that meet the color and difference conditions, and determine whether this maximum continuous gradient length Greater than the length critical value; calculating the mixing weight based on the maximum continuous gradient length corresponding to several rows and columns being greater than the length critical value; and mixing the original image and the compensated image according to the mixing weight.
Description
本發明是有關於一種影像處理方法，且特別是有關於區域調光(Local Dimming)的影像處理方法與顯示裝置。 The present invention relates to an image processing method, and more particularly to an image processing method and a display device related to local dimming.
一般來說，液晶顯示裝置都包含了背光模組，傳統的背光模組多採用固定式背光(Constant backlight)，而為了增加其對比，必須使用區域調光(Local Dimming)技術，其區域性地根據影像亮度的分佈情形來調整特定部分的背光亮度。例如，當顯示影像中較亮的區域時，背光會輸出高亮度；當顯示影像中較暗的區域時，則減弱背光的輸出亮度。藉此，具有區域調光控制的顯示器具有較高的動態對比與較低的消耗功率。然而，當採用區域調光時，一些具有特殊圖案(pattern)的影像會有不預期的效果，因此需要偵測這些圖案並作對應的處理。 Generally, liquid crystal display devices include a backlight module. Traditional backlight modules mostly use a constant backlight. To increase the contrast, local dimming technology must be used. Adjust the brightness of the backlight of a specific part according to the distribution of the brightness of the image. For example, when displaying bright areas in an image, the backlight outputs high brightness; when displaying dark areas in an image, the output brightness of the backlight is reduced. Therefore, the display with area dimming control has higher dynamic contrast and lower power consumption. However, when area dimming is used, some images with special patterns will have unexpected results, so these patterns need to be detected and processed accordingly.
本發明的實施例提出一種區域調光的影像處理 方法，適用於顯示裝置。影像處理方法包括：取得原始影像，並從原始影像中取得多個行與多個列，其中每一行與每一列都包括多個像素；對原始影像執行區域調光補償程序以取得補償後影像；對於每一行與每一列上的像素，判斷是否符合顏色條件與差異條件；在每一行與每一列中，計算符合顏色條件與差異條件的像素中的最大連續漸層長度，並判斷最大連續漸層長度是否大於長度臨界值；根據有幾個行與列所對應的最大連續漸層長度是大於長度臨界值來計算出混和權重；以及根據混和權重來混和原始影像與補償後影像。 An embodiment of the present invention provides an image processing for area dimming. The method is suitable for a display device. The image processing method includes: obtaining an original image, and obtaining multiple rows and columns from the original image, each of which includes multiple pixels; performing a region dimming compensation procedure on the original image to obtain a compensated image; For each row and column of pixels, determine whether it meets the color and difference conditions; in each row and each column, calculate the maximum continuous gradient length of the pixels that meet the color and difference conditions, and determine the maximum continuous gradient Whether the length is greater than the critical length; calculate the blending weight based on the maximum continuous gradient length corresponding to several rows and columns being greater than the critical length; and blend the original image and the compensated image based on the blending weight.
在一些實施例中，每一個像素包括多個灰階值。影像處理方法更包括：對於每一個像素，判斷任意兩個灰階值之間的差異是否小於一個顏色臨界值，若是則判斷像素符合顏色條件。 In some embodiments, each pixel includes multiple grayscale values. The image processing method further includes: for each pixel, determining whether the difference between any two grayscale values is less than a color threshold, and if so, determining whether the pixel meets the color condition.
在一些實施例中，影像處理方法更包括：對於每一個像素，判斷像素的亮度值與相鄰像素的亮度值之間的差異是否小於一個差異臨界值，若是則判斷像素符合差異條件。 In some embodiments, the image processing method further includes: for each pixel, determining whether a difference between the brightness value of the pixel and the brightness value of an adjacent pixel is less than a difference threshold, and if so, determining whether the pixel meets the difference condition.
在一些實施例中，其中計算符合顏色條件與差異條件的像素中的最大連續漸層長度的步驟包括：對於每一個像素，根據對應的灰階值計算出亮度值；以及計算符合顏色條件與差異條件的像素的亮度值中在對應的行或列中嚴格遞增或嚴格遞減的一最大長度以作為最大連續漸層長度。 In some embodiments, the step of calculating the maximum continuous gradient length in pixels that meet the color and difference conditions includes: for each pixel, calculating the brightness value according to the corresponding grayscale value; and calculating the color condition and difference A maximum length of the luminance value of the condition pixel that is strictly increased or decreased in the corresponding row or column is used as the maximum continuous gradient length.
在一些實施例中，計算混和權重的步驟包括：計算有幾個行所對應的最大連續漸層長度是大於長度臨界 值以取得行數目；計算有幾個列所對應的最大連續漸層長度是大於長度臨界值以取得列數目；以及取得行數目與列數目之間的最大值，並取得此最大值相對於上述列或行的數目的比值以作為混和權重。 In some embodiments, the step of calculating the blending weight includes: calculating that the maximum continuous gradient length corresponding to several rows is greater than the length critical Value to obtain the number of rows; calculate the maximum continuous gradient length corresponding to several columns that is greater than the critical length to obtain the number of columns; and obtain the maximum value between the number of rows and the number of columns, and obtain this maximum value relative to the above The ratio of the number of columns or rows is used as the blending weight.
在一些實施例中，根據混和權重來混和原始影像與補償後影像的步驟包括：將一預設值減去混和權重以取得補償權重；以及將原始影像與混和權重相乘的結果加上補償後影像與補償權重相乘的結果。 In some embodiments, the step of blending the original image and the compensated image according to the blending weight includes: subtracting a preset value from the blending weight to obtain a compensation weight; and adding a compensation result after multiplying the original image with the blending weight The result of multiplying the image with the compensation weight.
以另外一個角度來說，本發明的實施例提出一種顯示裝置，包括顯示面板、背光模組與邏輯電路。背光模組包括多個發光單元。邏輯電路用以取得原始影像，從原始影像中取得多個行與多個列，並對原始影像執行區域調光補償程序以取得補償後影像。邏輯電路用以對於每一行與每一列上的像素，判斷是否符合顏色條件與差異條件。在每一行與每一列中，邏輯電路用以計算符合顏色條件與差異條件的像素中的最大連續漸層長度，並判斷最大連續漸層長度是否大於一個長度臨界值。邏輯電路用以根據有幾個行與列所對應的最大連續漸層長度是大於長度臨界值來計算出一個混和權重。邏輯電路用以根據混和權重來混和原始影像與補償後影像。 From another perspective, an embodiment of the present invention provides a display device including a display panel, a backlight module, and a logic circuit. The backlight module includes a plurality of light emitting units. The logic circuit is used for obtaining the original image, obtaining multiple rows and columns from the original image, and performing a region dimming compensation procedure on the original image to obtain a compensated image. The logic circuit is used to determine whether the pixels on each row and each column meet the color and difference conditions. In each row and each column, the logic circuit is used to calculate the maximum continuous gradient length in pixels that meet the color and difference conditions, and determine whether the maximum continuous gradient length is greater than a length critical value. The logic circuit is used to calculate a blending weight according to the maximum continuous gradient length corresponding to several rows and columns being greater than the length critical value. The logic circuit is used to mix the original image and the compensated image according to the mixing weight.
在一些實施例中，對於每一個像素，邏輯電路用以判斷像素中任意兩個灰階值之間的差異是否小於一顏色臨界值，若是則判斷此像素符合顏色條件。 In some embodiments, for each pixel, the logic circuit is used to determine whether the difference between any two grayscale values in the pixel is less than a color threshold, and if so, it is determined that the pixel meets the color condition.
在一些實施例中，對於每一個像素，邏輯電路 用以根據對應的灰階值計算出亮度值。對於每一個像素，邏輯電路用以判斷像素的亮度值與相鄰像素的亮度值之間的差異是否小於一差異臨界值，若是則判斷像素符合差異條件。 In some embodiments, for each pixel, the logic circuit Used to calculate the brightness value according to the corresponding gray level value. For each pixel, the logic circuit is used to determine whether the difference between the brightness value of the pixel and the brightness value of an adjacent pixel is less than a critical difference value; if so, it is determined that the pixel meets the difference condition.
在一些實施例中，對於每一個像素，邏輯電路用以根據對應的灰階值計算出亮度值。邏輯電路用以計算符合顏色條件與差異條件的像素的亮度值中在對應的行或列中嚴格遞增或嚴格遞減的最大長度以作為最大連續漸層長度。 In some embodiments, for each pixel, the logic circuit is configured to calculate a brightness value according to a corresponding grayscale value. The logic circuit is used to calculate the maximum length of the brightness value of the pixel that meets the color conditions and the difference conditions in the corresponding row or column strictly increasing or decreasing strictly as the maximum continuous gradient length.
在一些實施例中，邏輯電路用以計算有幾個行所對應的最大連續漸層長度是大於長度臨界值以取得行數目。邏輯電路用以計算有幾個列所對應的最大連續漸層長度是大於長度臨界值以取得列數目。邏輯電路用以取得行數目與列數目之間的最大值，並取得此最大值相對於上述列或行的數目的比值以作為混和權重。 In some embodiments, the logic circuit is used to calculate that the maximum continuous gradient length corresponding to several rows is greater than the length threshold to obtain the number of rows. The logic circuit is used to calculate that the maximum continuous gradient length corresponding to several columns is greater than the critical length to obtain the number of columns. The logic circuit is used to obtain the maximum value between the number of rows and the number of columns, and to obtain the ratio of the maximum value to the number of columns or rows as the mixing weight.
在一些實施例中，邏輯電路用以將預設值減去混和權重以取得補償權重，並將原始影像與混和權重相乘的結果加上補償後影像與補償權重相乘的結果。 In some embodiments, the logic circuit is configured to subtract the mixing weight from the preset value to obtain the compensation weight, and multiply the result of multiplying the original image by the mixing weight and the result of multiplying the compensated image by the compensation weight.
在本發明實施例提出的影像處理方法中，可以偵測出特殊圖案並作相對應的處理，藉此提升顯示品質。 In the image processing method provided by the embodiment of the present invention, a special pattern can be detected and processed accordingly, thereby improving display quality.
為讓本發明的上述特徵和優點能更明顯易懂，下文特舉實施例，並配合所附圖式作詳細說明如下。 In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.
100‧‧‧顯示裝置 100‧‧‧ display device
110‧‧‧顯示面板 110‧‧‧display panel
120‧‧‧背光模組 120‧‧‧ backlight module
130‧‧‧邏輯電路 130‧‧‧Logic Circuit
201~206‧‧‧影像 201 ~ 206‧‧‧Image
301、302、310‧‧‧區域 301, 302, 310‧‧‧ zones
401‧‧‧原始影像 401‧‧‧ original image
410、420、430‧‧‧程序 410, 420, 430‧‧‧ procedures
411‧‧‧權重 411‧‧‧weight
421‧‧‧補償後影像 421‧‧‧Image after compensation
431‧‧‧輸出影像 431‧‧‧Output image
610‧‧‧列 610‧‧‧column
p1~pN‧‧‧像素 p 1 ~ p N ‧‧‧ pixels
620‧‧‧曲線 620‧‧‧curve
701~706‧‧‧步驟 701 ~ 706‧‧‧step
[圖1]是根據一實施例繪示顯示裝置的示意圖。 1 is a schematic diagram illustrating a display device according to an embodiment.
[圖2]是根據一些實施例繪示具有特殊圖案的影像示意圖。 FIG. 2 is a schematic diagram illustrating an image with a special pattern according to some embodiments.
[圖3]是根據一實施例繪示條紋與發光單元之間的關係示意圖。 3 is a schematic diagram illustrating a relationship between a stripe and a light emitting unit according to an embodiment.
[圖4]是根據一實施例繪示區域調光的顯示方法的流程示意圖。 4 is a schematic flowchart of a display method for area dimming according to an embodiment.
[圖5]是根據一實施例繪示影像中多個行與多個列的示意圖。 5 is a schematic diagram illustrating multiple rows and multiple columns in an image according to an embodiment.
[圖6]是根據一實施例繪示判斷條紋的示意圖。 FIG. 6 is a schematic diagram of determining a fringe according to an embodiment.
[圖7]是根據一實施例繪示區域調光的影像處理方法。 FIG. 7 illustrates an image processing method for area dimming according to an embodiment.
圖1是根據一實施例繪示顯示裝置的示意圖。請參照圖1，顯示裝置100可為螢幕或包含螢幕的任意電子裝置，例如為智慧型手機、平板電腦、筆記型電腦等等。顯示裝置100包括了顯示面板110、背光模組120與邏輯電路130。 FIG. 1 is a schematic diagram illustrating a display device according to an embodiment. Referring to FIG. 1, the display device 100 may be a screen or any electronic device including a screen, such as a smart phone, a tablet computer, a notebook computer, and the like. The display device 100 includes a display panel 110, a backlight module 120, and a logic circuit 130.
顯示面板110可為任意適合的液晶顯示面板，例如為邊緣場切換(fringe field switching，FFS)、共面切換(in-plane switching，IPS)模式、扭轉向列型(twisted nematic，TN)、垂直配向(vertical alignment，VA)等顯示面板。 The display panel 110 may be any suitable liquid crystal display panel, such as fringe field switching (FFS), in-plane switching (IPS) mode, twisted nematic (TN), vertical Display panels such as vertical alignment (VA).
背光模組120包括有多個發光單元121~128，這些發光單元例如為發光二極體(light emitting diode，LED)，透過控制這些發光二極體的亮度，可以實施區域調光(local dimming)的機制。然而，圖1中發光單元121~128的數目與設置位置僅為範例，在其他實施例中背光模組120可以有更多或更少個發光單元，並且這些發光單元可以有其他的設置位置。在圖1中發光模組120為直下式(Direct-lit)發光模組，但在其他實施例中也可以為側光式(edge-lit)發光模組，只要具有多個發光單元以在不同區域提供不同強度的光源，皆在本說明書的範圍內。 The backlight module 120 includes a plurality of light emitting units 121 to 128. These light emitting units are, for example, light emitting diodes (LEDs). By controlling the brightness of these light emitting diodes, local dimming can be implemented. Mechanisms. However, the number and setting positions of the light-emitting units 121 to 128 in FIG. 1 are merely examples. In other embodiments, the backlight module 120 may have more or fewer light-emitting units, and these light-emitting units may have other setting positions. In FIG. 1, the light-emitting module 120 is a direct-lit light-emitting module, but in other embodiments, it may be an edge-lit light-emitting module, as long as it has multiple light-emitting units to Areas providing light sources of different intensities are all within the scope of this description.
邏輯電路130是用以取得一個原始影像，並對原始影像執行一些影像處理程序以後將影像提供給顯示面板110來顯示。在一些實施例中，邏輯電路130也可以控制各個發光單元121~128的發光強度。邏輯電路130例如為時間控制器(timing controller)，但在其他實施例中也可以為顯示裝置100中任意的晶片或電路。 The logic circuit 130 is used to obtain an original image, and after performing some image processing procedures on the original image, the image is provided to the display panel 110 for display. In some embodiments, the logic circuit 130 can also control the light emission intensity of each light-emitting unit 121-128. The logic circuit 130 is, for example, a timing controller, but may be any chip or circuit in the display device 100 in other embodiments.
圖2是根據一些實施例繪示具有特殊圖案的影像示意圖。圖2中繪示了6張影像201~206，這些影像都具有灰階逐漸改變(可沿著X方向或是Y方向)的條紋，當使用區域調光方法時，這些影像可能會有不預期的效果。舉例來說，請參照圖3，其中繪示了一個條紋上像素的灰階值，橫軸表示位置(可為X軸或是Y軸)，縱軸表示灰階值的大小。從圖3可以看出，區域301內所有像素的灰階值都類似，且低於區域302內所有像素的灰階值。如果沒有區域調光，則 區域301與區域302之間可以看出一條明顯的邊緣。然而，當採用區域調光機制時，發光單元並不一定對齊這兩個區域301、302，因此會改變邊緣附近的顯示效果。舉例來說，發光單元121是位於區域301內，而發光單元122則同時在區域301、302內。如果發光單元122的發光強度大於發光單元121的發光強度，則區域310內的灰階值會被增強而大於區域301內其他的灰階值；或者，如果發光單元122的發光強度小於發光單元121的發光強度，則區域310內的灰階值會被減弱而小於區域301內其他的灰階值。以下將提出一個影像處理方法，來偵測並處理這樣的特殊圖案。 FIG. 2 is a schematic diagram illustrating an image with a special pattern according to some embodiments. Figure 2 shows 6 images 201 to 206. These images have stripes with gradually changing gray levels (can be along the X direction or the Y direction). When the area dimming method is used, these images may have unexpected results. Effect. For example, please refer to FIG. 3, which shows the grayscale values of pixels on a stripe, the horizontal axis represents the position (can be the X axis or the Y axis), and the vertical axis represents the magnitude of the grayscale value. It can be seen from FIG. 3 that the grayscale values of all pixels in the area 301 are similar and lower than the grayscale values of all pixels in the area 302. If there is no area dimming, then A clear edge can be seen between the regions 301 and 302. However, when the area dimming mechanism is adopted, the light emitting unit does not necessarily align the two areas 301 and 302, so the display effect near the edges will be changed. For example, the light emitting unit 121 is located in the area 301, and the light emitting unit 122 is located in the areas 301 and 302 at the same time. If the light emitting intensity of the light emitting unit 122 is greater than the light emitting intensity of the light emitting unit 121, the grayscale value in the region 310 will be enhanced and greater than other grayscale values in the region 301; , The grayscale value in the region 310 will be weakened and smaller than other grayscale values in the region 301. An image processing method is proposed below to detect and process such special patterns.
值得一提的是，圖3中發光單元121、122具有明顯的範圍，但此僅為示意。在一些實施例中，發光單元121、122發出的光線還會經過光導(light guide)等元件，因此發光單元121、122發出的光線會擴散至周圍的區域，並不如圖3所示的每個發光單元有明顯的範圍。然而，這並不影響上述在邊緣附近產生不良效果的描述。 It is worth mentioning that the light emitting units 121 and 122 in FIG. 3 have obvious ranges, but this is only for illustration. In some embodiments, the light emitted by the light emitting units 121 and 122 also passes through elements such as a light guide. Therefore, the light emitted by the light emitting units 121 and 122 will spread to the surrounding area. The light emitting unit has a clear range. However, this does not affect the above description of the adverse effects occurring near the edges.
圖4是根據一實施例繪示區域調光的影像處理方法的流程示意圖。請參照圖4，首先取得原始影像401，此原始影像401為彩色影像，例如包括紅、綠、藍等三個通道。換言之，每個像素都包括對應至紅色、綠色、藍色的三個灰階值。 FIG. 4 is a schematic flowchart of an image processing method for area dimming according to an embodiment. Referring to FIG. 4, an original image 401 is first obtained, and the original image 401 is a color image, for example, including three channels of red, green, and blue. In other words, each pixel includes three grayscale values corresponding to red, green, and blue.
此原始影像401會輸入至區域調光補償程序420，此程序420會根據區域調光的結果來調整原始影像401中一些像素的灰階值。舉例來說，請參照圖1，原始影 像401可根據發光單元121~128的位置被分為多個區塊，每個區塊內會計算灰階值的平均，並計算這些灰階值的直方圖，根據這些資訊可以決定出對應的發光單元的強度，例如灰階值較低時發光單元的發光強度可以較弱。接下來，根據這些發光單元的發光強度來調整原始影像401中對應像素的灰階值，舉例來說，如果某像素對應的發光單元被調弱，則此像素的灰階值會增加，藉此讓所顯示的效果和原始影像401一致，在經過區域調光補償程序420以後可以得到補償後影像421。然而，上述的補償方式僅為了說明，本發明並不限制區域調光補償程序420的內容。 The original image 401 is input to an area dimming compensation program 420, and the program 420 adjusts the grayscale values of some pixels in the original image 401 according to the result of the area dimming. For example, referring to FIG. 1, the original video The image 401 can be divided into multiple blocks according to the positions of the light emitting units 121 to 128. Each block will calculate the average of the grayscale values and calculate a histogram of these grayscale values. Based on this information, the corresponding The intensity of the light-emitting unit, for example, when the gray-scale value is low, the light-emitting intensity of the light-emitting unit may be weak. Next, the grayscale value of the corresponding pixel in the original image 401 is adjusted according to the light emitting intensity of these light emitting units. For example, if the light emitting unit corresponding to a pixel is weakened, the grayscale value of this pixel will increase, thereby The displayed effect is consistent with the original image 401, and the compensated image 421 can be obtained after passing through the area dimming compensation program 420. However, the above compensation method is merely for illustration, and the present invention does not limit the content of the area dimming compensation program 420.
另一方面，原始影像401會輸入至程序410，用以偵測特殊圖案並計算出一個混和權重411。具體來說，請參照圖5，圖5是根據一實施例繪示影像中多個行與多個列的示意圖。在圖5的實施例中，是從原始影像中取得M列與N行，其中M、N為正整數。在一些實施例中，M可以小於原始影像401的高度，並且N可以小於原始影像401的寬度。例如，原始影像401的大小為720x480，而M等於60，N等於90，也就是說上述的M列與N行是從原始影像401中降取樣8倍而取得。然而，上述降取樣的倍率僅為範例，在其他實施例中也可以降取樣更多倍或是不降取樣，本發明並不在此限。在一些實施例中，正整數M與正整數N為相同。 On the other hand, the original image 401 is input to the program 410 for detecting a special pattern and calculating a blending weight 411. Specifically, please refer to FIG. 5, which is a schematic diagram illustrating multiple rows and multiple columns in an image according to an embodiment. In the embodiment of FIG. 5, M columns and N rows are obtained from the original image, where M and N are positive integers. In some embodiments, M may be smaller than the height of the original image 401 and N may be smaller than the width of the original image 401. For example, the size of the original image 401 is 720x480, and M is equal to 60 and N is equal to 90, which means that the above-mentioned M columns and N rows are obtained by downsampling 8 times from the original image 401. However, the above-mentioned downsampling magnification is merely an example, and in other embodiments, the downsampling may be performed more times or without downsampling, and the present invention is not limited thereto. In some embodiments, the positive integer M is the same as the positive integer N.
對於所取得的每一行與每一列，都會判斷是否存在漸層條紋(如圖2所示)。首先，對於所取得的每一行與每一列上的像素，判斷這些像素是否符合一個顏色條件與一 個差異條件。請參照圖6，在此以列610為例來說明，對於行的處理可以類推，因此並不贅述。列610具有像素p1~pN(共有N個像素，但在一些實施例中也可以降取樣K倍，即僅處理列610上的N/K個像素)。顏色條件是要判斷像素是否接近灰色，在一些實施例中，是判斷一個像素的三個灰階值中任意兩個灰階值之間的差異是否小於一個顏色臨界值，若是則判斷此像素符合此顏色條件。換個角度來說，若用R、G、B來分別代表紅色、綠色、藍色三個灰階值，並且ABS()代表兩個灰階值之間的絕對差(absolute difference)，則必須符合以下的方程式(1)~(3)才可判斷符合顏色條件。 For each row and column obtained, it will be determined whether there are gradient stripes (as shown in Figure 2). First, for each pixel obtained in each row and column, determine whether the pixels meet a color condition and a difference condition. Please refer to FIG. 6, where column 610 is taken as an example for description. The processing of the row can be deduced by analogy, so it will not be repeated here. The column 610 has pixels p 1 to p N (a total of N pixels, but in some embodiments, it may be down-sampled by K times, that is, only N / K pixels on the column 610 are processed). The color condition is to determine whether the pixel is close to gray. In some embodiments, it is to determine whether the difference between any two gray levels of the three gray levels of a pixel is less than a color threshold. If so, it is determined that the pixel meets This color condition. To put it another way, if R, G, and B are used to represent the three grayscale values of red, green, and blue, respectively, and ABS () represents the absolute difference between the two grayscale values, they must meet The following equations (1) to (3) can be used to determine that the color conditions are met.
ABS(R,G)<Tcolor…(1) ABS (R , G) <T color … (1)
ABS(G,B)<Tcolor…(2) ABS (G , B) <T color … (2)
ABS(B,R)<Tcolor…(3) ABS (B , R) <T color … (3)
其中Tcolor為顏色臨界值。然而，在一些實施例中也可以將紅色、綠色、藍色三個灰階值轉換至另一個色彩空間，例如HSI色彩空間，並判斷在此色彩空間的色度(hue)是否在一個預設範圍內，若是則判斷符合顏色條件。或者，在一些實施例中，也可以判斷紅色、綠色、藍色三個灰階值是否分別在三個預設範圍內，若是則符合顏色條件。 Where T color is the color threshold. However, in some embodiments, the three grayscale values of red, green, and blue can also be converted to another color space, such as the HSI color space, and it is determined whether the hue of the color space is in a preset If it is within the range, it is judged that the color condition is met. Alternatively, in some embodiments, it may also be determined whether the three grayscale values of red, green, and blue are within three preset ranges, and if so, the color conditions are met.
此外，差異條件是要判斷相鄰兩個像素的亮度是否差異不大。舉例來說，對於每一個像素，可以根據三個灰階值計算出一個亮度值，在此實施例中可取紅色、綠色、藍色三個灰階值的最大值作為亮度值(luminance)，然而在 其他實施例中也可以將這三個灰階值轉換至另一個色彩空間，並取得其中的亮度值，例如HSI色彩空間中的強度(intensity)。然而，本領域具有通常知識者當可採用其他色彩空間中的亮度值，例如YCbCr色彩空間中的亮度值Y，本發明並不在此限。接下來，對於每一個像素，判斷此像素的亮度值與相鄰像素的亮度值之間的差異是否小於一差異臨界值，若是則判斷此像素符合差異條件。舉例來說，若以Li表示像素pi的亮度值，其中i為正整數，則對於像素pi，若符合以下方程式(4)則表示符合差異條件。 In addition, the difference condition is to determine whether the brightness of two adjacent pixels is not significantly different. For example, for each pixel, a brightness value can be calculated according to the three grayscale values. In this embodiment, the maximum value of the three grayscale values of red, green, and blue can be taken as the brightness value. However, In other embodiments, the three grayscale values can also be converted to another color space, and the brightness value can be obtained, such as the intensity in the HSI color space. However, those skilled in the art can use the brightness values in other color spaces, such as the brightness value Y in the YCbCr color space, and the present invention is not limited thereto. Next, for each pixel, it is determined whether the difference between the brightness value of the pixel and the brightness value of an adjacent pixel is less than a difference threshold, and if so, it is determined that the pixel meets the difference condition. For example, if the pixel represents a luminance value L i p i, where i is a positive integer, p i for the pixel, if they meet the following equation (4) indicates the difference meet the conditions.
ABS(Li ,Li-1)<T diff ...(4) ABS (L i , L i-1 ) < T diff ... (4)
其中Tdiff為差異臨界值。然而，在其他實施例中也可以套用一個高通濾波器在像素pi上，當此高通濾波器的結果小於一個預設值時，則判斷像素pi符合差異條件，本發明並不限制此高通濾波器的大小與係數。 Where T diff is the difference threshold. However, in other embodiments, a high-pass filter may also be applied to the pixel p i . When the result of the high-pass filter is less than a preset value, it is determined that the pixel p i meets the difference condition, and the present invention does not limit the high-pass Filter size and coefficient.
請參照圖6，符合顏色條件與差異條件的像素才會進行下一個步驟，在此將不符合條件的像素p1、p8、p9標記起來，也就是說像素p2~p7會進行下一個步驟。接下來，計算符合顏色條件與差異條件的像素中的一個最大連續漸層長度，此最大連續漸層長度是表示在對應的行或列中亮度值嚴格遞增或嚴格遞減的最大長度。舉例來說，可先將像素p3的亮度值減去像素p2的亮度值，根據此差值的正負號判斷是遞增或是遞減。接下來將像素p4的亮度值減去像素p3的亮度值，判斷是否持續遞增或遞減。如果像素p2與像素p3之間為遞增(差值為正)，且像素p3與像素p4之間也為遞增 (差值也為正)，則最大連續漸層長度至少為2，以此類推，直到變為遞減(差值為負)為止。同樣地，如果像素p2與像素p3之間為遞減，且像素p3與像素p4也為遞減，則最大連續漸層長度也是至少為2，以此類推，直到變為遞增為止。在此實施例中，從像素p2至像素p7為一個片段，此片段的灰階值如曲線620所示是嚴格遞增，因此這個片段的長度為6。在列610中可能有多個連續遞增或遞減的片段，其中最大的長度便是上述的最大連續漸層長度。接下來，判斷此最大連續漸層長度是否大於一個長度臨界值，若大於長度臨界值則表示此列或行中有漸層的條紋。在一些實施例中，此長度臨界值為8，但本發明並不在此限。 Please refer to Fig. 6. Only the pixels that meet the color and difference conditions will proceed to the next step. Here, the pixels that do not meet the conditions p 1 , p 8 , and p 9 will be marked, that is, pixels p 2 to p 7 will be processed. The next step. Next, calculate a maximum continuous gradient length of the pixels that meet the color and difference conditions. This maximum continuous gradient length is the maximum length that indicates that the brightness value is strictly increased or decreased in the corresponding row or column. For example, the brightness value of the pixel p 3 may be subtracted from the brightness value of the pixel p 2 first, and it may be determined whether to increase or decrease according to the sign of the difference. Next, the luminance value of the pixel p p 4 of subtracting the pixel luminance value 3, it is determined whether the continuous increment or decrement. If pixel p 2 and pixel p 3 are increasing (the difference is positive) and pixel p 3 and pixel p 4 are also increasing (the difference is also positive), then the maximum continuous gradient length is at least 2, And so on, until it becomes decreasing (the difference is negative). Similarly, if the pixel p 2 and the pixel p 3 are decreasing, and the pixels p 3 and p 4 are also decreasing, the maximum continuous gradient length is also at least 2, and so on, until it becomes increasing. In this embodiment, the pixel p 2 to the pixel p 7 is a segment, and the gray level value of this segment is strictly increased as shown by the curve 620, so the length of this segment is 6. There may be multiple consecutively increasing or decreasing segments in column 610, and the maximum length is the above-mentioned maximum continuous gradient length. Next, determine whether the maximum continuous gradient length is greater than a length critical value. If it is greater than the length critical value, it indicates that there are gradient stripes in this column or row. In some embodiments, the length critical value is 8, but the present invention is not limited thereto.
接下來，根據上述N行與M列中有幾個行與列所對應的最大連續漸層長度是大於長度臨界值可計算出一混和權重。在一些實施例中，是計算有幾個行所對應的最大連續漸層長度是大於長度臨界值以取得行數目，假設此行數目為n，n為正整數。此外，再計算有幾個列所對應的最大連續漸層長度是大於長度臨界值以取得列數目，假設此列數目是m，m為正整數。接下來，取得行數目n與列數目m之間的一最大值max(m,n)，並取得此最大值相對於行數目N或列數目M的比值以作為混和權重。在一些實施例中，行數目N與列數目M是相等，上述的混和權重可表示為max(m,n)/M。請參照圖4，在程序410之後便可輸出混和權重411。 Next, a blending weight can be calculated based on the maximum continuous gradient length corresponding to several rows and columns in the above N rows and M columns that is greater than the length critical value. In some embodiments, the maximum continuous gradient length corresponding to several rows is calculated to be greater than the critical length to obtain the number of rows. It is assumed that the number of rows is n and n is a positive integer. In addition, the maximum continuous gradient length corresponding to several columns is greater than the length critical value to obtain the number of columns. It is assumed that the number of columns is m, and m is a positive integer. Next, obtain a maximum value max (m, n) between the number of rows n and the number of columns m, and obtain the ratio of this maximum value to the number of rows N or the number of columns M as the mixing weight. In some embodiments, the number of rows N and the number of columns M are equal, and the above-mentioned mixing weight may be expressed as max (m, n) / M. Referring to FIG. 4, the blending weight 411 can be output after the program 410.
在上述實施例中，是根據行數目n與列數目m的 最大值來計算混和權重，但在其他實施例中也可以根據行數目n與列數目m的總和來計算混和權重，例如(n+m)/2M，本發明並不在此限。在一些實施例中，當總行數目N與總列數目M不相等時，是根據行數目n與列數目m的最大值與對應的總行數目N或總列數目M之間的比值來計算混和權重。例如，如果n>m，則混和權重為n/N；如果m>n，則混和權重為m/M。 In the above embodiment, it is based on the number of rows n and the number of columns m. The maximum value is used to calculate the mixing weight, but in other embodiments, the mixing weight may also be calculated according to the sum of the number of rows n and the number of columns m, such as (n + m) / 2M, which is not limited in the present invention. In some embodiments, when the total number of rows N is not equal to the total number of columns M, the mixing weight is calculated according to the ratio between the maximum value of the number of rows n and the number of columns m and the corresponding total number of rows N or the total number of columns M. . For example, if n> m, the mixing weight is n / N; if m> n, the mixing weight is m / M.
在程序430中，根據此混和權重411來混和原始影像401與補償後影像421，藉此產生輸出影像431。具體來說，當混和權重411越大時，表示原始影像401中有特殊圖案的機率越大，因此程度上應採用較多的原始影像401來產生輸出影像431；相反地，當混和權重411越小時，表示原始影像401中有特殊圖案的機率越小，因此程度上應採用較多的補償後影像421。舉例來說，在一些實施例中可以用權重總和(weighting sum)來混和原始影像401與補償後影像421，亦即將一預設值(例如為1)減去混和權重(表示為P)以取得補償權重(1-P)，將混和權重P與原始影像401的每個像素相乘，並將相乘的結果加上補償後影像421與補償權重(1-P)相乘的結果，最後得到輸出影像431。以另一個角度來說，若將原始影像401以O來表示，將補償後影像421以B來表示，則程序430可以表示為以下方程式(5)。 In the program 430, the original image 401 and the compensated image 421 are mixed according to the mixing weight 411, thereby generating an output image 431. Specifically, when the blending weight 411 is larger, it means that the original image 401 is more likely to have a special pattern. Therefore, more raw images 401 should be used to generate the output image 431. On the contrary, when the blending weight 411 is larger, Hour means that the probability of having a special pattern in the original image 401 is smaller, so more compensated image 421 should be used to the extent. For example, in some embodiments, a weighting sum may be used to mix the original image 401 and the compensated image 421, that is, a preset value (for example, 1) is subtracted from the mixing weight (represented as P) to obtain Compensation weight (1-P). Multiply the blending weight P with each pixel of the original image 401, and add the result of the multiplication to the result of multiplying the compensated image 421 with the compensation weight (1-P). Output image 431. From another perspective, if the original image 401 is represented by 0 and the compensated image 421 is represented by B, the program 430 can be expressed as the following equation (5).
P×O+(1-P)×B...(5) P × O + (1-P) × B ... (5)
在一些實施例中，區域調光的機制還可包括其他程序，例如對輸出影像431執行空間上的濾波器，或者在 產生多張輸出影像以後對這些輸出影像執行時間上的濾波器等等。本發明並不限制上述的影像處理方法要怎麼與其他演算法結合。 In some embodiments, the area dimming mechanism may further include other programs, such as performing a spatial filter on the output image 431, or After generating multiple output images, temporal filtering is performed on these output images, and so on. The invention does not limit how the image processing method described above can be combined with other algorithms.
圖7是根據一實施例繪示區域調光的影像處理方法。請參照圖7，在步驟701中，取得原始影像，並從原始影像中取得多個行與多個列。在步驟702中，對原始影像執行區域調光補償程序以取得補償後影像。在步驟703中，對於每一行與每一列上的像素，判斷是否符合顏色條件與差異條件。在步驟704中，在每一行與每一列中，計算符合顏色條件與差異條件的像素中的最大連續漸層長度，並判斷最大連續漸層長度是否大於長度臨界值。在步驟705中，根據有幾個行與列所對應的最大連續漸層長度是大於長度臨界值來計算出混和權重。在步驟706中，根據混和權重來混和原始影像與補償後影像。然而，圖7中各步驟已詳細說明如上，在此便不再贅述。值得注意的是，圖7中各步驟可以實作為多個程式碼或是電路，本發明並不在此限。此外，圖7的方法可以搭配以上實施例使用，也可以單獨使用。換言之，圖7的各步驟之間也可以加入其他的步驟。 FIG. 7 illustrates an image processing method for area dimming according to an embodiment. Referring to FIG. 7, in step 701, an original image is obtained, and multiple rows and multiple columns are obtained from the original image. In step 702, a region dimming compensation procedure is performed on the original image to obtain a compensated image. In step 703, for each pixel in each row and column, it is determined whether the color condition and the difference condition are met. In step 704, in each row and each column, calculate the maximum continuous gradient length in pixels that meet the color and difference conditions, and determine whether the maximum continuous gradient length is greater than the length critical value. In step 705, the blending weight is calculated according to the fact that the maximum continuous gradient length corresponding to several rows and columns is greater than the length critical value. In step 706, the original image and the compensated image are mixed according to the mixing weight. However, the steps in FIG. 7 have been described in detail above, and will not be repeated here. It should be noted that each step in FIG. 7 can be implemented as multiple codes or circuits, and the present invention is not limited thereto. In addition, the method in FIG. 7 may be used in conjunction with the above embodiments, or may be used alone. In other words, other steps may be added between the steps in FIG. 7.
在本發明實施例提出的影像處理方法與顯示裝置中，透過三個條件的判斷(顏色條件、差異條件、最大連續漸層長度是否大於長度臨界值)可判斷出條紋的圖案，再根據權重來混和原始影像與補償後影像，藉此可以有較好的顯示效果。 In the image processing method and display device provided by the embodiment of the present invention, the pattern of stripes can be judged through the judgment of three conditions (color condition, difference condition, and whether the maximum continuous gradient length is greater than a critical length), and then the weight pattern is obtained. Blend the original image and the compensated image to get better display results.
雖然本發明已以實施例揭露如上，然其並非用 以限定本發明，任何所屬技術領域中具有通常知識者，在不脫離本發明的精神和範圍內，當可作些許的更動與潤飾，故本發明的保護範圍當視後附的申請專利範圍所界定者為準。 Although the present invention has been disclosed above by way of example, it is not intended to be used. To limit the present invention, anyone with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be regarded as the scope of the attached patent application. Defined shall prevail.
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| CN1934614A (en) * | 2004-03-26 | 2007-03-21 | 皇家飞利浦电子股份有限公司 | Display device comprising an adjustable light source |
| US20110141154A1 (en) * | 2009-12-11 | 2011-06-16 | Hee-Won Ahn | Local dimming driving method and device of liquid crystal display device |
| US20110148940A1 (en) * | 2009-12-18 | 2011-06-23 | Min-Chul Byun | Driving method for local dimming of liquid crystal display device and apparatus using the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1934614A (en) * | 2004-03-26 | 2007-03-21 | 皇家飞利浦电子股份有限公司 | Display device comprising an adjustable light source |
| US20110141154A1 (en) * | 2009-12-11 | 2011-06-16 | Hee-Won Ahn | Local dimming driving method and device of liquid crystal display device |
| US20110148940A1 (en) * | 2009-12-18 | 2011-06-23 | Min-Chul Byun | Driving method for local dimming of liquid crystal display device and apparatus using the same |
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