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TWI767750B - Image white balance method and system thereof - Google Patents

Image white balance method and system thereof Download PDF

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TWI767750B
TWI767750B TW110121237A TW110121237A TWI767750B TW I767750 B TWI767750 B TW I767750B TW 110121237 A TW110121237 A TW 110121237A TW 110121237 A TW110121237 A TW 110121237A TW I767750 B TWI767750 B TW I767750B
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TW202248957A (en
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許巍嚴
鄭漢昌
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國立中正大學
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Abstract

The present disclosure provides an image white balance method and a system thereof. A first color converting step is performed to convert a first image corresponding to a first color format into a converted image corresponding to a second color format according to a color converting process. A converted image includes a plurality of image average values and a maximum luminance value. An absolute difference generating step is performed to process the image average values according to a calculating process to generate a plurality of average absolute differences. A white pixel area filtering step is performed to process the average absolute differences according to a filtering process to filter out a white pixel area from the converted image. A candidate white pixel retaining step is performed to retain a plurality of candidate white pixels from the white pixel area according to a selected weight value. A second color converting step is performed to calculate the maximum luminance value according to the candidate white pixels to generate a plurality of gain parameters, and then convert the first image into a second image according to the gain parameters. Therefore, it is favorable for avoiding the problem of color cast in the image.

Description

影像白平衡方法及其系統Image white balance method and system

本發明是關於一種影像的處理方法及其系統，特別是關於一種影像白平衡方法及其系統。The present invention relates to an image processing method and system, in particular to an image white balance method and system.

近年來，由於習知的自動白平衡方法(Automatic White Balance)大多需要假設影像處於特定情況下才進行白平衡調整，因此習知的自動白平衡方法無法適用於前述特定情況以外的影像。此外，習知的自動白平衡方法在對於不同的色溫下的多張連續影像進行調整時，容易會出現色偏的問題而導致在連續且不同的色溫情況下無法準確地調整影像。由此可知，習知的自動白平衡方法不管在室內或室外都有色溫的問題存在，其中在室內拍攝時會因為燈泡有從暖系色溫到冷系色溫的影響，在室外拍攝時則會因為太陽位置、天氣溼度以及視野可見度而受到影響。In recent years, since most of the conventional automatic white balance methods need to assume that the image is in a specific situation before performing white balance adjustment, the conventional automatic white balance method cannot be applied to images other than the above-mentioned specific situation. In addition, when the conventional automatic white balance method is used to adjust a plurality of continuous images with different color temperatures, the problem of color shift is likely to occur, so that the images cannot be accurately adjusted under the continuous and different color temperature conditions. It can be seen from this that the conventional automatic white balance method has the problem of color temperature whether indoors or outdoors. When shooting indoors, it will be affected by the light bulb from warm color temperature to cool color temperature, and when shooting outdoors, it will be caused by Sun position, weather humidity, and field of view visibility are affected.

有鑑於此，針對習知的自動白平衡方法所存在之問題點，如何建立一種可避免影像出現色偏問題的影像白平衡方法及其系統，實為民眾所殷切企盼，亦係相關業者須努力研發突破之目標及方向。In view of this, in view of the problems existing in the conventional automatic white balance method, how to establish an image white balance method and system that can avoid the problem of color cast in the image is really eagerly expected by the public, and it is also necessary for the relevant industry to work hard. The goal and direction of R&D breakthrough.

因此，本發明之目的在於提供一種影像白平衡方法及其系統，其透過在第一影像中選取出多個候選亮度值，再利用計算此些候選亮度值而產生多個增益參數，然後根據此些增益參數轉換第一影像為第二影像，進而避免第一影像在連續且不同的色溫調整上的色偏問題。Therefore, an object of the present invention is to provide an image white balance method and a system thereof, which select a plurality of candidate luminance values in a first image, and then use the candidate luminance values to generate a plurality of gain parameters, and then generate a plurality of gain parameters according to the These gain parameters convert the first image into the second image, thereby avoiding the color shift problem of the first image in continuous and different color temperature adjustment.

依據本發明的一實施方式提供一種影像白平衡方法，其用以轉換一第一影像為一第二影像。影像白平衡方法包含一第一色彩轉換步驟、一絕對差產生步驟、一似白點區域篩選步驟、一候選白點保留步驟以及一第二色彩轉換步驟。第一色彩轉換步驟係驅動一處理單元根據一色彩轉換程序轉換對應一第一色彩格式之第一影像為對應一第二色彩格式之一轉換影像。轉換影像包含複數影像平均值及一最大亮度值。絕對差產生步驟係驅動處理單元根據一運算程序處理此些影像平均值而產生複數平均絕對差。似白點區域篩選步驟係驅動處理單元根據一篩選程序處理此些平均絕對差而從轉換影像篩選出一似白點區域。候選白點保留步驟係驅動處理單元根據一選取權重值從似白點區域中保留複數候選白點。第二色彩轉換步驟係驅動處理單元根據此些候選白點計算最大亮度值以產生複數增益參數，然後根據此些增益參數轉換第一影像為對應第一色彩格式之第二影像。An embodiment of the present invention provides an image white balance method for converting a first image into a second image. The image white balance method includes a first color conversion step, an absolute difference generation step, a white point-like area screening step, a candidate white point retention step, and a second color conversion step. The first color conversion step drives a processing unit to convert a first image corresponding to a first color format into a converted image corresponding to a second color format according to a color conversion program. The converted image includes an average value of the complex images and a maximum luminance value. In the step of generating the absolute difference, the driving processing unit processes the average values of the images according to an operation program to generate a complex average absolute difference. In the step of screening the white-spot-like region, the driving processing unit processes the average absolute differences according to a screening procedure to filter out a white-spot-like region from the converted image. In the step of retaining candidate white points, the driving processing unit retains a plurality of candidate white points from the white point-like region according to a selection weight value. In the second color conversion step, the driving processing unit calculates the maximum luminance value according to the candidate white points to generate complex gain parameters, and then converts the first image into a second image corresponding to the first color format according to the gain parameters.

藉此，本發明之影像白平衡方法根據篩選程序調整似白點區域的範圍大小，並透過選取權重值來選取出指定數量的候選白點，然後計算出增益參數，進而轉換第一影像為第二影像，達到有效地解決在連續多張影像中進行色溫調整所造成的色偏問題。Thereby, the image white balance method of the present invention adjusts the size of the area of the white point-like area according to the screening procedure, selects a specified number of candidate white points by selecting the weight value, then calculates the gain parameter, and then converts the first image into the first image. Two images, to effectively solve the color shift problem caused by color temperature adjustment in multiple consecutive images.

前述實施方式之其他實施例如下：前述運算程序包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標及一像素數目，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，像素數目表示為
Figure 02_image019
且符合下式：
Figure 02_image021
；
Figure 02_image023
。 Other examples of the aforementioned implementation manner are as follows: the aforementioned computing procedure includes the image average values, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, and a number of pixels, and the image average values are respectively expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the number of pixels is expressed as
Figure 02_image019
and conform to the following formula:
Figure 02_image021
;
Figure 02_image023
.

前述實施方式之其他實施例如下：前述篩選程序包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標、一拓展權重值及一符號函數，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，拓展權重值表示為
Figure 02_image025
，符號函數表示為
Figure 02_image027
且符合下式：
Figure 02_image029
；
Figure 02_image031
。 Other examples of the aforementioned embodiments are as follows: the aforementioned screening procedure includes the image mean values, the mean absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, an extended weight value, and a sign function, the images The mean values are expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the extended weight value is expressed as
Figure 02_image025
, the symbolic function is expressed as
Figure 02_image027
and conform to the following formula:
Figure 02_image029
;
Figure 02_image031
.

前述實施方式之其他實施例如下：前述影像白平衡方法更包含一權重值調整步驟。權重值調整步驟包含一第一調整步驟與一第二調整步驟。第一調整步驟係驅動處理單元根據一亮度值比對程序調整拓展權重值。第二調整步驟係驅動處理單元根據一分數值比對程序調整選取權重值。其中，處理單元根據已調整的拓展權重值與已調整的選取權重值重新執行第一色彩轉換步驟、絕對差產生步驟、似白點區域篩選步驟、候選白點保留步驟及第二色彩轉換步驟而產生對應第一色彩格式之已調整的第二影像。Other examples of the aforementioned embodiments are as follows: the aforementioned image white balance method further includes a weight value adjustment step. The weight value adjustment step includes a first adjustment step and a second adjustment step. In the first adjustment step, the drive processing unit adjusts the extended weight value according to a luminance value comparison procedure. In the second adjustment step, the drive processing unit adjusts the selection weight value according to a score comparison procedure. Wherein, the processing unit re-executes the first color conversion step, the absolute difference generation step, the white point-like area screening step, the candidate white point retention step, and the second color conversion step according to the adjusted extension weight value and the adjusted selection weight value to obtain a An adjusted second image corresponding to the first color format is generated.

前述實施方式之其他實施例如下：前述亮度值比對程序包含拓展權重值、一目標亮度值及一參考亮度值，拓展權重值表示為

Figure 02_image025
，目標亮度值表示為
Figure 02_image033
，參考亮度值表示為
Figure 02_image035
且符合下式：
Figure 02_image037
。 Other examples of the aforementioned embodiments are as follows: the aforementioned luminance value comparison procedure includes an extended weight value, a target luminance value and a reference luminance value, and the extended weight value is expressed as
Figure 02_image025
, the target brightness value is expressed as
Figure 02_image033
, the reference luminance value is expressed as
Figure 02_image035
and conform to the following formula:
Figure 02_image037
.

前述實施方式之其他實施例如下：前述分數值比對程序包含選取權重值、一目標分數值及一參考分數值，選取權重值表示為

Figure 02_image001
，目標分數值表示為
Figure 02_image039
，參考分數值表示為
Figure 02_image041
且符合下式：
Figure 02_image043
。 Other examples of the aforementioned embodiments are as follows: the aforementioned score value comparison procedure includes a selection weight value, a target score value and a reference score value, and the selection weight value is expressed as
Figure 02_image001
, the target score value is expressed as
Figure 02_image039
, the reference score value is expressed as
Figure 02_image041
and conform to the following formula:
Figure 02_image043
.

依據本發明的另一實施方式提供一種影像白平衡系統，其用以轉換一第一影像為一第二影像。影像白平衡系統包含一儲存單元以及一處理單元。儲存單元用以存取第一影像、一色彩轉換程序、一運算程序、一篩選程序及一選取權重值。處理單元連接儲存單元，且經配置以實施一第一色彩轉換步驟、一絕對差產生步驟、一似白點區域篩選步驟、一候選白點保留步驟及一第二色彩轉換步驟。第一色彩轉換步驟係根據色彩轉換程序轉換對應一第一色彩格式之第一影像為對應一第二色彩格式之一轉換影像。轉換影像包含複數影像平均值及一最大亮度值。絕對差產生步驟係根據運算程序處理此些影像平均值而產生複數平均絕對差。似白點區域篩選步驟係根據篩選程序處理此些平均絕對差而從轉換影像篩選出一似白點區域。候選白點保留步驟係根據選取權重值從似白點區域中保留複數候選白點。第二色彩轉換步驟係根據此些候選白點計算最大亮度值以產生複數增益參數，然後根據此些增益參數轉換第一影像為對應第一色彩格式之第二影像。Another embodiment of the present invention provides an image white balance system for converting a first image into a second image. The image white balance system includes a storage unit and a processing unit. The storage unit is used for accessing the first image, a color conversion program, an operation program, a filtering program and a selection weight value. The processing unit is connected to the storage unit, and is configured to implement a first color conversion step, an absolute difference generation step, a white point-like area screening step, a candidate white point retention step, and a second color conversion step. The first color conversion step is to convert a first image corresponding to a first color format into a converted image corresponding to a second color format according to a color conversion program. The converted image includes an average value of the complex images and a maximum luminance value. The absolute difference generating step is to process the average values of the images according to the operation program to generate a complex average absolute difference. The white-spot-like region screening step processes the mean absolute differences according to a screening procedure to filter out a white-spot-like region from the converted image. The candidate white point retaining step is to retain a plurality of candidate white points from the white point-like region according to the selected weight value. The second color conversion step calculates the maximum luminance value according to the candidate white points to generate complex gain parameters, and then converts the first image into a second image corresponding to the first color format according to the gain parameters.

藉此，本發明之影像白平衡系統向外拓展轉換影像的似白點區域，且加入選取權重值來選取出指定數量的候選白點，然後計算出增益參數，進而轉換第一影像為第二影像，達到有效地解決在連續色溫調整上的色偏問題。Thereby, the image white balance system of the present invention expands the white point-like area of the converted image outward, and adds a selection weight value to select a specified number of candidate white points, then calculates the gain parameter, and then converts the first image into the second image, to effectively solve the color shift problem in continuous color temperature adjustment.

前述實施方式之其他實施例如下：前述運算程序包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標及一像素數目，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，像素數目表示為
Figure 02_image019
且符合下式：
Figure 02_image021
；
Figure 02_image023
。 Other examples of the aforementioned implementation manner are as follows: the aforementioned computing procedure includes the image average values, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, and a number of pixels, and the image average values are respectively expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the number of pixels is expressed as
Figure 02_image019
and conform to the following formula:
Figure 02_image021
;
Figure 02_image023
.

前述實施方式之其他實施例如下：前述篩選程序包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標、一拓展權重值及一符號函數，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，拓展權重值表示為
Figure 02_image025
，符號函數表示為
Figure 02_image027
且符合下式：
Figure 02_image029
；
Figure 02_image031
。 Other examples of the aforementioned embodiments are as follows: the aforementioned screening procedure includes the image mean values, the mean absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, an extended weight value, and a sign function, the images The mean values are expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the extended weight value is expressed as
Figure 02_image025
, the symbolic function is expressed as
Figure 02_image027
and conform to the following formula:
Figure 02_image029
;
Figure 02_image031
.

前述實施方式之其他實施例如下：前述處理單元經配置以更實施一權重值調整步驟。權重值調整步驟包含一第一調整步驟與一第二調整步驟。第一調整步驟係根據一亮度值比對程序調整拓展權重值。第二調整步驟係根據一分數值比對程序調整選取權重值。其中，處理單元根據已調整的拓展權重值與已調整的選取權重值重新執行第一色彩轉換步驟、絕對差產生步驟、似白點區域篩選步驟、候選白點保留步驟及第二色彩轉換步驟而產生對應第一色彩格式已調整的第二影像。Other examples of the aforementioned embodiments are as follows: the aforementioned processing unit is configured to further implement a weight value adjustment step. The weight value adjustment step includes a first adjustment step and a second adjustment step. The first adjustment step is to adjust the extended weight value according to a luminance value comparison procedure. The second adjustment step is to adjust the selection weight value according to a score comparison procedure. The processing unit re-executes the first color conversion step, the absolute difference generation step, the white point-like region screening step, the candidate white point retention step, and the second color conversion step according to the adjusted extension weight value and the adjusted selection weight value to achieve A second image adjusted corresponding to the first color format is generated.

前述實施方式之其他實施例如下：前述亮度值比對程序包含拓展權重值、一目標亮度值及一參考亮度值，拓展權重值表示為

Figure 02_image025
，目標亮度值表示為
Figure 02_image033
，參考亮度值表示為
Figure 02_image035
且符合下式：
Figure 02_image037
。 Other examples of the aforementioned embodiments are as follows: the aforementioned luminance value comparison procedure includes an extended weight value, a target luminance value and a reference luminance value, and the extended weight value is expressed as
Figure 02_image025
, the target brightness value is expressed as
Figure 02_image033
, the reference luminance value is expressed as
Figure 02_image035
and conform to the following formula:
Figure 02_image037
.

前述實施方式之其他實施例如下：前述分數值比對程序包含選取權重值、一目標分數值及一參考分數值，選取權重值表示為

Figure 02_image001
，目標分數值表示為
Figure 02_image039
，參考分數值表示為
Figure 02_image041
且符合下式：
Figure 02_image043
。 Other examples of the aforementioned embodiments are as follows: the aforementioned score value comparison procedure includes a selection weight value, a target score value and a reference score value, and the selection weight value is expressed as
Figure 02_image001
, the target score value is expressed as
Figure 02_image039
, the reference score value is expressed as
Figure 02_image041
and conform to the following formula:
Figure 02_image043
.

以下將參照圖式說明本發明之複數個實施例。為明確說明起見，許多實務上的細節將在以下敘述中一併說明。然而，應瞭解到，這些實務上的細節不應用以限制本發明。也就是說，在本發明部分實施例中，這些實務上的細節是非必要的。此外，為簡化圖式起見，一些習知慣用的結構與元件在圖式中將以簡單示意的方式繪示之；並且重複之元件將可能使用相同的編號表示之。Several embodiments of the present invention will be described below with reference to the drawings. For the sake of clarity, many practical details are set forth in the following description. It should be understood, however, that these practical details should not be used to limit the invention. That is, in some embodiments of the present invention, these practical details are unnecessary. In addition, for the purpose of simplifying the drawings, some well-known and conventional structures and elements will be shown in a simplified and schematic manner in the drawings; and repeated elements may be denoted by the same reference numerals.

此外，本文中當某一元件(或單元或模組等)「連接/連結」於另一元件，可指所述元件是直接連接/連結於另一元件，亦可指某一元件是間接連接/連結於另一元件，意即，有其他元件介於所述元件及另一元件之間。而當有明示某一元件是「直接連接/連結」於另一元件時，才表示沒有其他元件介於所述元件及另一元件之間。而第一、第二、第三等用語只是用來描述不同元件，而對元件本身並無限制，因此，第一元件亦可改稱為第二元件。且本文中之元件/單元/電路之組合非此領域中之一般周知、常規或習知之組合，不能以元件/單元/電路本身是否為習知，來判定其組合關係是否容易被技術領域中之通常知識者輕易完成。In addition, when a certain element (or unit or module, etc.) is "connected/connected" to another element herein, it may mean that the element is directly connected/connected to another element, or that a certain element is indirectly connected /Connected to another element means that there is another element between the element and the other element. When it is expressly stated that an element is "directly connected/connected" to another element, it means that no other element is interposed between the element and the other element. The terms first, second, and third are only used to describe different elements, and do not limit the elements themselves. Therefore, the first element can also be renamed as the second element. And the combination of elements/units/circuits in this article is not a commonly known, conventional or well-known combination in this field, and it cannot be determined whether the combination relationship of the elements/units/circuits is well-known or not easily understood by those in the technical field. Usually the knowledgeable can do it easily.

請參閱第1圖，其係繪示依照本發明一第一實施例的影像白平衡方法100的流程示意圖。如第1圖所示，影像白平衡方法100包含一第一色彩轉換步驟S1、一絕對差產生步驟S2、一似白點區域篩選步驟S3、一候選白點保留步驟S4以及一第二色彩轉換步驟S5，且用以轉換一第一影像110為一第二影像140。Please refer to FIG. 1 , which is a schematic flowchart of an image white balance method 100 according to a first embodiment of the present invention. As shown in FIG. 1, the image white balance method 100 includes a first color conversion step S1, an absolute difference generation step S2, a similar white point area screening step S3, a candidate white point retention step S4, and a second color conversion step Step S5 is used for converting a first image 110 into a second image 140 .

第一色彩轉換步驟S1係驅動一處理單元根據一色彩轉換程序321轉換對應一第一色彩格式之第一影像110為對應一第二色彩格式之轉換影像120。轉換影像120包含複數影像平均值及一最大亮度值。The first color conversion step S1 drives a processing unit to convert the first image 110 corresponding to a first color format into a converted image 120 corresponding to a second color format according to a color conversion program 321 . The converted image 120 includes the average value of the complex images and a maximum luminance value.

絕對差產生步驟S2係驅動處理單元根據一運算程序322處理此些影像平均值而產生複數平均絕對差。In the absolute difference generating step S2 , the driving processing unit processes the average values of the images according to an operation program 322 to generate a complex average absolute difference.

似白點區域篩選步驟S3係驅動處理單元根據一篩選程序323處理此些平均絕對差而從轉換影像120篩選出一似白點區域130。In the step S3 of screening the white-spot-like region, the driving processing unit processes the average absolute differences according to a screening program 323 to filter out a white-spot-like region 130 from the converted image 120 .

候選白點保留步驟S4係驅動處理單元根據一選取權重值

Figure 02_image001
從似白點區域130中保留複數候選白點131。 The candidate white point retention step S4 is that the drive processing unit selects a weight value according to a
Figure 02_image001
A plurality of candidate white points 131 are reserved from the white point-like area 130 .

第二色彩轉換步驟S5係驅動處理單元根據此些候選白點131計算最大亮度值以產生複數增益參數，然後根據此些增益參數轉換第一影像110為對應第一色彩格式之第二影像140。In the second color conversion step S5, the driving processing unit calculates the maximum luminance value according to the candidate white points 131 to generate complex gain parameters, and then converts the first image 110 into the second image 140 corresponding to the first color format according to the gain parameters.

藉此，本發明之影像白平衡方法100根據篩選程序323調整似白點區域130的範圍大小，並透過選取權重值

Figure 02_image001
來選取出指定數量的候選白點131，然後計算出增益參數，進而轉換第一影像110為第二影像140，可有效地解決在連續多張影像中進行色溫調整所造成的色偏問題。 Thereby, the image white balance method 100 of the present invention adjusts the size of the range of the white point-like area 130 according to the screening program 323, and selects the weight value by selecting the weight value.
Figure 02_image001
to select a specified number of candidate white points 131, then calculate the gain parameter, and then convert the first image 110 into the second image 140, which can effectively solve the color shift problem caused by color temperature adjustment in consecutive images.

具體而言，第一色彩格式可為應用於三原色的一RGB色彩空間，第二色彩格式可為應用於顏色編碼的一YUV色彩空間。色彩轉換程序321主要用以將採用RGB色彩空間的第一影像110轉換成採用YUV色彩空間的轉換影像120。一般的攝影裝置所產生的影像，其像素分量分別為對應紅色分量的紅色彩值、對應綠色分量的綠色彩值及對應藍色分量的藍色彩值。處理單元透過色彩轉換程序321將第一影像110內的各個像素之RGB分量轉換為對應各個像素之一亮度值(即Y)、一色度值(即

Figure 02_image011
)及另一色度值(即
Figure 02_image013
)。接著，處理單元將轉換影像120的加總像素值除以轉換影像120的影像大小而產生此些影像平均值。處理單元將轉換影像120內的所有像素中選取亮度值最大者作為此最大亮度值。 Specifically, the first color format may be an RGB color space applied to three primary colors, and the second color format may be a YUV color space applied to color coding. The color conversion program 321 is mainly used to convert the first image 110 using the RGB color space into the converted image 120 using the YUV color space. In an image generated by a general photographing device, the pixel components are respectively a red color value corresponding to the red component, a green color value corresponding to the green component, and a blue color value corresponding to the blue component. The processing unit converts the RGB components of each pixel in the first image 110 into a luminance value (ie Y) and a chrominance value (ie, Y) corresponding to each pixel through the color conversion program 321 .
Figure 02_image011
) and another chromaticity value (ie
Figure 02_image013
). Next, the processing unit divides the summed pixel value of the converted image 120 by the image size of the converted image 120 to generate the image averages. The processing unit selects the maximum brightness value among all the pixels in the converted image 120 as the maximum brightness value.

於絕對差產生步驟S2中，運算程序322可包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標及一像素數目，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，像素數目表示為
Figure 02_image019
且符合下列式子(1)與式子(2)：
Figure 02_image021
(1)；
Figure 02_image023
(2)。 In the absolute difference generating step S2, the operation program 322 may include the average values of the images, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, and a number of pixels, and the image averages are respectively expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the number of pixels is expressed as
Figure 02_image019
And it conforms to the following formulas (1) and (2):
Figure 02_image021
(1);
Figure 02_image023
(2).

其中，平均絕對差

Figure 02_image007
、
Figure 02_image009
主要用以尋找轉換影像120的色度中心點。
Figure 02_image045
及
Figure 02_image047
表示在轉換影像120中位於水平座標
Figure 02_image015
與垂直座標
Figure 02_image017
的像素所對應的色度值。 where the mean absolute difference
Figure 02_image007
,
Figure 02_image009
It is mainly used to find the chromaticity center point of the converted image 120 .
Figure 02_image045
and
Figure 02_image047
Indicates the horizontal coordinates in the converted image 120
Figure 02_image015
with vertical coordinates
Figure 02_image017
The chrominance value corresponding to the pixel of .

請一併參閱第1圖與第2圖，其中第2圖係繪示本發明之似白點區域130及多個候選白點131的示意圖。於似白點區域篩選步驟S3中，篩選程序323可包含此些影像平均值、此些平均絕對差、複數色度值、一水平座標、一垂直座標、一拓展權重值及一符號函數，此些影像平均值分別表示為

Figure 02_image003
與
Figure 02_image005
，此些平均絕對差分別表示為
Figure 02_image007
與
Figure 02_image009
，此些色度值分別表示為
Figure 02_image011
與
Figure 02_image013
，水平座標表示為
Figure 02_image015
，垂直座標表示為
Figure 02_image017
，拓展權重值表示為
Figure 02_image025
，符號函數表示為
Figure 02_image027
且符合下列式子(3)與式子(4)：
Figure 02_image029
(3)；
Figure 02_image031
(4)。 Please refer to FIG. 1 and FIG. 2 together, wherein FIG. 2 is a schematic diagram illustrating the white point-like region 130 and a plurality of candidate white points 131 according to the present invention. In the screening step S3 of the like-white point area, the screening procedure 323 may include the image average values, the average absolute differences, the complex chromaticity values, a horizontal coordinate, a vertical coordinate, an extended weight value, and a sign function. The average values of these images are expressed as
Figure 02_image003
and
Figure 02_image005
, these mean absolute differences are expressed as
Figure 02_image007
and
Figure 02_image009
, these chromaticity values are expressed as
Figure 02_image011
and
Figure 02_image013
, the horizontal coordinates are expressed as
Figure 02_image015
, the vertical coordinates are expressed as
Figure 02_image017
, the extended weight value is expressed as
Figure 02_image025
, the symbolic function is expressed as
Figure 02_image027
And it conforms to the following formulas (3) and (4):
Figure 02_image029
(3);
Figure 02_image031
(4).

在第2圖中，水平座標

Figure 02_image015
的單位為色度值
Figure 02_image013
，垂直座標
Figure 02_image017
的單位為色度值
Figure 02_image011
。此外，拓展權重值
Figure 02_image025
主要用以調整以第2圖中的色度中心點Q為基準向外拓展的似白點區域130之範圍，且拓展權重值
Figure 02_image025
的數值可為1，但本發明不以此為限。 In Figure 2, the horizontal coordinates
Figure 02_image015
The unit is the chromaticity value
Figure 02_image013
, vertical coordinates
Figure 02_image017
The unit is the chromaticity value
Figure 02_image011
. In addition, expanding the weight value
Figure 02_image025
It is mainly used to adjust the range of the white-like area 130 that expands outward based on the chromaticity center point Q in the second figure, and to expand the weight value.
Figure 02_image025
The value of can be 1, but the present invention is not limited to this.

需說明的是，習知的自動白平衡方法在篩選似白點時固定了篩選範圍而導致有些接近顏色空間的真正白點沒被篩選到。然而，由第2圖、式子(3)及式子(4)可知，本發明考慮到首張的第一影像110的色溫值與對應首張的第一影像110之似白點區域130不一定會與下一張的另一第一影像110的色溫值與對應下一張的第一影像110之似白點區域130相同，因此在篩選似白點區域130時加入了拓展權重值

Figure 02_image025
，來調整以色度中心點Q為基準向外拓展的似白點區域130之範圍，其中第2圖內的虛線方框為習知的自動白平衡方法所對應的似白點區域。 It should be noted that the conventional automatic white balance method fixes the screening range when screening the pseudo-white points, so that some true white points close to the color space are not screened. However, as can be seen from FIG. 2, Equation (3) and Equation (4), the present invention considers that the color temperature value of the first first image 110 is not the same as the white point region 130 corresponding to the first first image 110 The color temperature value of the next first image 110 must be the same as the white point area 130 corresponding to the next first image 110 , so an extended weight value is added when screening the white point area 130
Figure 02_image025
, to adjust the range of the white point-like area 130 extending outward with the chromaticity center point Q as the reference, wherein the dotted box in Figure 2 is the white point-like area corresponding to the conventional automatic white balance method.

另外，習知的自動白平衡方法選取候選白點的方式是直接選取似白點區域內的似白點亮度值較大者作為候選白點。例如：亮度值為前10%者作為候選白點；不同的是，於候選白點保留步驟S4中，本發明之選取候選白點131的方式係在似白點區域130內選取似白點亮度值較大的前選取權重值

Figure 02_image001
者作為此些候選白點131，因此選取權重值
Figure 02_image001
主要用以在似白點區域130中控制候選白點131的選取數量，且選取權重值
Figure 02_image001
的數值可為0.1，但本發明不以此為限。 In addition, the conventional automatic white balance method selects the candidate white point by directly selecting the white point candidate with the larger brightness value of the white point in the white point-like area. For example, the top 10% of the brightness values are used as candidate white points; the difference is that in the candidate white point retention step S4, the method of selecting the candidate white points 131 in the present invention is to select the brightness of the white point-like points in the white-like point area 130 Pre-select weight value with larger value
Figure 02_image001
as these candidate white points 131, so the weight value is selected
Figure 02_image001
It is mainly used to control the selection number of candidate white points 131 in the white point-like area 130, and to select a weight value
Figure 02_image001
The value of can be 0.1, but the present invention is not limited to this.

於第二色彩轉換步驟S5中，各個候選白點131具有對應第二色彩格式的一候選亮度值(即Y)、一候選色度值(即

Figure 02_image011
)及另一候選色度值(即
Figure 02_image013
)。處理單元分別計算此些候選白點131的複數個候選亮度值、複數個候選色度值及複數個另一候選色度值而產生一平均亮度值、一平均色度值及另一平均色度值。接著，處理單元根據色彩轉換程序321的一逆轉換程序(即YUV色彩空間轉換RGB色彩空間)分別計算平均亮度值、平均色度值及另一平均色度值而產生對應第一色彩格式的一平均紅色彩值、一平均綠色彩值及一平均藍色彩值。接著，處理單元計算平均紅色彩值、平均綠色彩值及平均藍色彩值及最大亮度值以產生此些增益參數且符合下列式子(5)、式子(6)及式子(7)：
Figure 02_image049
(5)；
Figure 02_image051
(6)；
Figure 02_image053
(7)。 In the second color conversion step S5, each candidate white point 131 has a candidate luminance value (ie Y) and a candidate chrominance value (ie, Y) corresponding to the second color format.
Figure 02_image011
) and another candidate chroma value (ie
Figure 02_image013
). The processing unit calculates a plurality of candidate luminance values, a plurality of candidate chrominance values and a plurality of other candidate chrominance values of the candidate white points 131 respectively to generate an average luminance value, an average chrominance value and another average chrominance value value. Next, the processing unit calculates the average luminance value, the average chromaticity value and another average chromaticity value according to an inverse conversion procedure of the color conversion procedure 321 (ie, the YUV color space converts the RGB color space) to generate a corresponding first color format. An average red color value, an average green color value, and an average blue color value. Next, the processing unit calculates the average red color value, the average green color value, the average blue color value and the maximum luminance value to generate these gain parameters and conform to the following equations (5), (6) and (7):
Figure 02_image049
(5);
Figure 02_image051
(6);
Figure 02_image053
(7).

其中，最大亮度值表示為

Figure 02_image055
，平均紅色彩值表示為
Figure 02_image057
，平均綠色彩值表示為
Figure 02_image059
，平均藍色彩值表示為
Figure 02_image061
，此些增益參數分別表示為
Figure 02_image063
、
Figure 02_image065
及
Figure 02_image067
。 Among them, the maximum brightness value is expressed as
Figure 02_image055
, the average red color value is expressed as
Figure 02_image057
, the average green color value is expressed as
Figure 02_image059
, the average blue color value is expressed as
Figure 02_image061
, these gain parameters are expressed as
Figure 02_image063
,
Figure 02_image065
and
Figure 02_image067
.

處理單元根據此些增益參數

Figure 02_image063
、
Figure 02_image069
轉換第一影像110的紅色彩值、綠色彩值及藍色彩值為對應第一色彩格式之第二影像140的另一紅色彩值、另一綠色彩值及另一藍色彩值且符合下列式子(8)、式子(9)及式子(10)：
Figure 02_image071
(8)；
Figure 02_image073
(9)；
Figure 02_image075
(10)。 The processing unit according to these gain parameters
Figure 02_image063
,
Figure 02_image069
Convert the red color value, green color value and blue color value of the first image 110 to another red color value, another green color value and another blue color value of the second image 140 corresponding to the first color format and conform to the following formula Sub (8), Equation (9) and Equation (10):
Figure 02_image071
(8);
Figure 02_image073
(9);
Figure 02_image075
(10).

其中，第一影像110的紅色彩值、綠色彩值及藍色彩值分別表示為

Figure 02_image077
、
Figure 02_image079
及
Figure 02_image081
，第二影像140的另一紅色彩值、另一綠色彩值及另一藍色彩值分別表示為
Figure 02_image083
、
Figure 02_image085
及
Figure 02_image087
。 The red color value, green color value and blue color value of the first image 110 are respectively expressed as
Figure 02_image077
,
Figure 02_image079
and
Figure 02_image081
, another red color value, another green color value and another blue color value of the second image 140 are respectively expressed as
Figure 02_image083
,
Figure 02_image085
and
Figure 02_image087
.

請一併參閱第3圖與第4圖，其中第3圖係繪示依照本發明一第二實施例的影像白平衡方法200的流程示意圖；以及第4圖係繪示第3圖的影像白平衡方法200之權重值調整步驟S6的流程示意圖。第二實施例中的第一色彩轉換步驟S1、絕對差產生步驟S2、似白點區域篩選步驟S3、候選白點保留步驟S4及第二色彩轉換步驟S5與第一實施例中的流程步驟相同，在此不另贅述。Please refer to FIG. 3 and FIG. 4 together, wherein FIG. 3 shows a schematic flowchart of an image white balance method 200 according to a second embodiment of the present invention; and FIG. 4 shows the image white balance of FIG. 3 A schematic flowchart of the weight value adjustment step S6 of the balancing method 200 . The first color conversion step S1 , the absolute difference generation step S2 , the similar white point area screening step S3 , the candidate white point retention step S4 and the second color conversion step S5 in the second embodiment are the same as those in the first embodiment. , which will not be repeated here.

如第3圖與第4圖所示，影像白平衡方法200更包含一權重值調整步驟S6，且權重值調整步驟S6可包含一第一調整步驟S61與一第二調整步驟S62。第一調整步驟S61係驅動處理單元根據一亮度值比對程序324調整拓展權重值

Figure 02_image025
。第二調整步驟S62係驅動處理單元根據一分數值比對程序325調整選取權重值
Figure 02_image001
。其中，處理單元根據已調整的調整拓展權重值
Figure 02_image025
與已調整的選取權重值
Figure 02_image001
重新執行下一次的第一色彩轉換步驟S1、絕對差產生步驟S2、似白點區域篩選步驟S3、候選白點保留步驟S4及第二色彩轉換步驟S5而產生對應第一色彩格式之已調整的第二影像140。須注意的是，在下一次(即第二次)的第一色彩轉換步驟S1中，處理單元會將第一影像110替換成尚未調整的第二影像140。 As shown in FIGS. 3 and 4, the image white balance method 200 further includes a weight value adjustment step S6, and the weight value adjustment step S6 may include a first adjustment step S61 and a second adjustment step S62. The first adjustment step S61 is that the drive processing unit adjusts the extended weight value according to a luminance value comparison program 324
Figure 02_image025
. In the second adjustment step S62, the drive processing unit adjusts the selection weight value according to a score comparison program 325
Figure 02_image001
. Among them, the processing unit expands the weight value according to the adjusted adjustment
Figure 02_image025
with the adjusted selection weight value
Figure 02_image001
Re-execute the next first color conversion step S1, absolute difference generation step S2, similar white point area screening step S3, candidate white point retention step S4 and second color conversion step S5 to generate an adjusted image corresponding to the first color format. The second image 140 . It should be noted that in the next (ie, the second) first color conversion step S1, the processing unit will replace the first image 110 with the second image 140 that has not been adjusted.

同理，處理單元遞迴地重複執行四次的第一色彩轉換步驟S1、絕對差產生步驟S2、似白點區域篩選步驟S3、候選白點保留步驟S4、第二色彩轉換步驟S5及權重值調整步驟S6；換言之，本發明會對首次的第一影像110進行至少五次的調整，以求得最後調整的第二影像140作為輸出影像。Similarly, the processing unit recursively executes the first color conversion step S1, the absolute difference generation step S2, the white point-like region screening step S3, the candidate white point retention step S4, the second color conversion step S5 and the weight value. Adjustment step S6; in other words, the present invention will adjust the first first image 110 at least five times to obtain the last adjusted second image 140 as the output image.

於第一調整步驟S61中，亮度值比對程序324可包含拓展權重值、一目標亮度值及一參考亮度值，拓展權重值表示為

Figure 02_image025
，目標亮度值表示為
Figure 02_image033
，參考亮度值表示為
Figure 02_image035
且符合下列式子(11)：
Figure 02_image037
(11)。 In the first adjustment step S61, the brightness value comparison program 324 may include an extended weight value, a target brightness value and a reference brightness value, and the extended weight value is expressed as:
Figure 02_image025
, the target brightness value is expressed as
Figure 02_image033
, the reference luminance value is expressed as
Figure 02_image035
And it conforms to the following formula (11):
Figure 02_image037
(11).

其中，拓展權重值

Figure 02_image025
的初始值為1，目標亮度值
Figure 02_image033
為當次的平均亮度值的Y值，參考亮度值
Figure 02_image035
為首張的第一影像110轉換至第二色彩格式的Y值和下一張的另一第一影像110轉換至第二色彩格式的Y值取平均後的Y值。本發明藉由式子(11)調整拓展權重值
Figure 02_image025
的大小，進而改變已調整的第二影像140的色溫走向與亮度，且拓展權重值
Figure 02_image025
的數值範圍可落在0.5-1.5之間，但本發明不限於此。 Among them, the extended weight value
Figure 02_image025
The initial value of 1, the target brightness value
Figure 02_image033
is the Y value of the current average brightness value, the reference brightness value
Figure 02_image035
A Y value obtained by averaging the Y value of the first image 110 converted to the second color format and the Y value of the next first image 110 converted to the second color format. The present invention adjusts the expansion weight value by formula (11)
Figure 02_image025
size, and then change the color temperature and brightness of the adjusted second image 140, and expand the weight value
Figure 02_image025
The numerical range of can fall between 0.5-1.5, but the present invention is not limited thereto.

於第二調整步驟S62中，分數值比對程序325可包含選取權重值、一目標分數值及一參考分數值，選取權重值表示為

Figure 02_image001
，目標分數值表示為
Figure 02_image039
，參考分數值表示為
Figure 02_image041
且符合下列式子(12)：
Figure 02_image043
(12)。 In the second adjustment step S62, the score comparison procedure 325 may include a selection weight value, a target score value and a reference score value, and the selection weight value is expressed as:
Figure 02_image001
, the target score value is expressed as
Figure 02_image039
, the reference score value is expressed as
Figure 02_image041
And it conforms to the following formula (12):
Figure 02_image043
(12).

其中，選取權重值

Figure 02_image001
的初始值為0.1，目標分數值
Figure 02_image039
為處理單元根據一CIE 2000色彩差異公式計算當次的第一影像110與第二影像140而產生的分數值。參考分數值
Figure 02_image041
為處理單元根據CIE 2000色彩差異公式計算首張的第一影像110和下一張的另一第一影像110而產生的另一分數值，且選取權重值
Figure 02_image001
的數值範圍可落在0.1-0.5之間，但本發明不限於此。 Among them, choose the weight value
Figure 02_image001
The initial value of 0.1, the target score value
Figure 02_image039
It is a score value generated by the processing unit calculating the current first image 110 and the second image 140 according to a CIE 2000 color difference formula. reference score
Figure 02_image041
is another score value generated by the processing unit calculating the first first image 110 and the next first image 110 according to the CIE 2000 color difference formula, and selecting the weight value
Figure 02_image001
The numerical range of can fall between 0.1-0.5, but the present invention is not limited thereto.

此外，於每一次的遞迴步驟中，參考亮度值

Figure 02_image035
會根據前次的目標分數值
Figure 02_image039
與參考分數值
Figure 02_image041
進行比較而選擇出下一次的參考亮度值
Figure 02_image035
。例如：若是前次的目標分數值
Figure 02_image039
為較低者，則處理單元利用當次第二影像140的Y值替換掉原參考亮度值
Figure 02_image035
並進入下次的遞迴運算；若是前次的參考分數值
Figure 02_image041
為較低者，則處理單元繼續沿用原參考亮度值
Figure 02_image035
並進入下次的遞迴運算。 In addition, in each recursive step, the reference luminance value
Figure 02_image035
will be based on the previous target score value
Figure 02_image039
with reference score values
Figure 02_image041
Compare and select the next reference brightness value
Figure 02_image035
. For example: if the previous target score value
Figure 02_image039
is the lower one, the processing unit replaces the original reference luminance value with the Y value of the current second image 140
Figure 02_image035
And enter the next recursive operation; if the previous reference score value
Figure 02_image041
is lower, the processing unit continues to use the original reference luminance value
Figure 02_image035
And enter the next recursive operation.

另外，於每一次的遞迴步驟中，參考分數值

Figure 02_image041
也會根據前次的目標分數值
Figure 02_image039
與參考分數值
Figure 02_image041
進行比較而選擇出下一次的參考分數值
Figure 02_image041
。例如：若是前次的目標分數值
Figure 02_image039
為較低者，則處理單元利用前次的目標分數值
Figure 02_image039
替換掉原參考分數值
Figure 02_image041
並進入下次的遞迴運算；若是前次的參考分數值
Figure 02_image041
為較低者，則處理單元繼續沿用原參考分數值
Figure 02_image041
並進入下次的遞迴運算。 In addition, in each recursive step, the reference score value
Figure 02_image041
Also based on the previous target score value
Figure 02_image039
with reference score values
Figure 02_image041
Compare and choose the next reference score value
Figure 02_image041
. For example: if the previous target score value
Figure 02_image039
is the lower, the processing unit uses the previous target score value
Figure 02_image039
Replace the original reference score value
Figure 02_image041
And enter the next recursive operation; if the previous reference score value
Figure 02_image041
is lower, the processing unit continues to use the original reference score value
Figure 02_image041
And enter the next recursive operation.

請一併參閱第1-4圖及第5圖，其中第5圖係繪示依照本發明一第三實施例的影像白平衡系統300的方塊示意圖。如1-5圖所示，影像白平衡系統300用以轉換一第一影像110為一第二影像140，且包含一攝影單元310、儲存單元320以及一處理單元330。攝影單元310用以拍攝一物體並輸出第一影像110。儲存單元320訊號連接攝影單元310，且用以存取第一影像110、一色彩轉換程序321、一運算程序322、一篩選程序323、一選取權重值

Figure 02_image001
、一拓展權重值
Figure 02_image025
、一亮度值比對程序324及一分數值比對程序325。處理單元330電性連接儲存單元320，且經配置以實施一第一色彩轉換步驟S1、一絕對差產生步驟S2、一似白點區域篩選步驟S3、一候選白點保留步驟S4及一第二色彩轉換步驟S5。 Please refer to FIGS. 1-4 and FIG. 5 together, wherein FIG. 5 is a block diagram illustrating an image white balance system 300 according to a third embodiment of the present invention. As shown in FIGS. 1-5 , the image white balance system 300 is used for converting a first image 110 into a second image 140 , and includes a photographing unit 310 , a storage unit 320 and a processing unit 330 . The photographing unit 310 is used for photographing an object and outputting the first image 110 . The storage unit 320 is connected to the photographing unit 310 by signals, and is used for accessing the first image 110, a color conversion program 321, an operation program 322, a filtering program 323, and a selection weight value
Figure 02_image001
, an extended weight value
Figure 02_image025
, a luminance value comparison program 324 and a fractional value comparison program 325 . The processing unit 330 is electrically connected to the storage unit 320, and is configured to implement a first color conversion step S1, an absolute difference generation step S2, a similar white point area screening step S3, a candidate white point retention step S4 and a second Color conversion step S5.

第一色彩轉換步驟S1係根據色彩轉換程序321轉換對應一第一色彩格式之第一影像110為對應一第二色彩格式之一轉換影像120。轉換影像120包含複數影像平均值及一最大亮度值。絕對差產生步驟S2係根據運算程序322處理此些影像平均值而產生複數平均絕對差。似白點區域篩選步驟S3係根據篩選程序323處理此些平均絕對差而從轉換影像120篩選出一似白點區域130。候選白點保留步驟S4係根據選取權重值

Figure 02_image001
從似白點區域130中保留複數候選白點131。第二色彩轉換步驟S5係根據此些候選白點131計算最大亮度值以產生複數增益參數，然後根據此些增益參數轉換第一影像110為對應第一色彩格式之第二影像140。 The first color conversion step S1 is to convert the first image 110 corresponding to a first color format into a converted image 120 corresponding to a second color format according to the color conversion program 321 . The converted image 120 includes the average value of the complex images and a maximum luminance value. The absolute difference generating step S2 is to process the average values of the images according to the operation program 322 to generate a complex average absolute difference. The white-spot-like region screening step S3 is to process the average absolute differences according to the screening program 323 to filter out a white-spot-like region 130 from the converted image 120 . The candidate white point retention step S4 is based on the selection weight value
Figure 02_image001
A plurality of candidate white points 131 are reserved from the white point-like area 130 . The second color conversion step S5 calculates the maximum luminance value according to the candidate white points 131 to generate complex gain parameters, and then converts the first image 110 into the second image 140 corresponding to the first color format according to the gain parameters.

此外，處理單元330經配置以更可實施一權重值調整步驟S6。權重值調整步驟S6可包含一第一調整步驟S61與一第二調整步驟S62。第一調整步驟S61係根據亮度值比對程序324調整拓展權重值

Figure 02_image025
。第二調整步驟S62係根據分數值比對程序325調整選取權重值
Figure 02_image001
。再者，處理單元330根據已調整的拓展權重值
Figure 02_image025
與已調整的選取權重值
Figure 02_image001
重新執行第一色彩轉換步驟S1、絕對差產生步驟S2、似白點區域篩選步驟S3、候選白點保留步驟S4及第二色彩轉換步驟S5而產生對應第一色彩格式已調整的第二影像140。處理單元330可為微處理器、中央處理器(Central Processing Unit；CPU)、影像處理器或其他電子處理器，本發明不以此為限。 In addition, the processing unit 330 is configured to further implement a weight value adjustment step S6. The weight value adjustment step S6 may include a first adjustment step S61 and a second adjustment step S62. The first adjustment step S61 is to adjust the extended weight value according to the brightness value comparison program 324
Figure 02_image025
. The second adjustment step S62 is to adjust the selection weight value according to the score comparison program 325
Figure 02_image001
. Furthermore, the processing unit 330 according to the adjusted extension weight value
Figure 02_image025
with the adjusted selection weight value
Figure 02_image001
Re-execute the first color conversion step S1, the absolute difference generation step S2, the similar white point area screening step S3, the candidate white point retention step S4, and the second color conversion step S5 to generate the second image 140 that has been adjusted corresponding to the first color format . The processing unit 330 may be a microprocessor, a central processing unit (CPU), an image processor or other electronic processors, and the invention is not limited thereto.

藉此，本發明之影像白平衡系統300向外拓展轉換影像120的似白點區域130，且加入選取權重值

Figure 02_image001
來選取出指定數量的候選白點131，然後計算出增益參數，進而轉換第一影像110為第二影像140，達到有效地解決在連續色溫調整上的色偏問題。 Thereby, the image white balance system 300 of the present invention expands the white point region 130 of the converted image 120 outward, and adds a selection weight value
Figure 02_image001
to select a specified number of candidate white points 131, then calculate the gain parameters, and then convert the first image 110 into the second image 140, so as to effectively solve the color shift problem in continuous color temperature adjustment.

綜上所述，本發明具有下列優點：其一，有效地解決在連續多張影像中進行色溫調整所造成的色偏問題。其二，透過加入拓展權重值來調整似白點區域的範圍大小，進而避免接近顏色空間的似白點沒被篩選到。其三，透過加入選取權重值可靈活地在不同色溫的情況下篩選出較適用數量的候選白點。To sum up, the present invention has the following advantages: First, it effectively solves the color shift problem caused by performing color temperature adjustment in multiple consecutive images. Second, by adding an extended weight value to adjust the size of the white-like point area, so as to prevent the white-like points close to the color space from not being screened. Third, by adding a selection weight value, a suitable number of candidate white points can be flexibly screened under different color temperatures.

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，任何熟習此技藝者，在不脫離本發明之精神和範圍內，當可作各種之更動與潤飾，因此本發明之保護範圍當視後附之申請專利範圍所界定者為準。Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be determined by the scope of the appended patent application.

100,200:影像白平衡方法 S1:第一色彩轉換步驟 S2:絕對差產生步驟 S3:似白點區域篩選步驟 S4:候選白點保留步驟 S5:第二色彩轉換步驟 S6:權重值調整步驟 S61:第一調整步驟 S62:第二調整步驟 110:第一影像 120:轉換影像 130:似白點區域 131:候選白點 140:第二影像 300:影像白平衡系統 310:攝影單元 320:儲存單元 321:色彩轉換程序 322:運算程序 323:篩選程序 324:亮度值比對程序 325:分數值比對程序 330:處理單元

Figure 02_image015
:水平座標
Figure 02_image017
:垂直座標
Figure 02_image011
,
Figure 02_image013
:色度值
Figure 02_image025
:篩選程序
Figure 02_image001
:選取權重值 Q:色度中心點100,200: image white balance method S1: first color conversion step S2: absolute difference generation step S3: similar white point area screening step S4: candidate white point retention step S5: second color conversion step S6: weight value adjustment step S61: first An adjustment step S62: Second adjustment step 110: First image 120: Converted image 130: Like white point area 131: Candidate white point 140: Second image 300: Image white balance system 310: Photography unit 320: Storage unit 321: Color conversion program 322: Operation program 323: Screening program 324: Brightness value comparison program 325: Fractional value comparison program 330: Processing unit
Figure 02_image015
: Horizontal coordinates
Figure 02_image017
: vertical coordinates
Figure 02_image011
,
Figure 02_image013
: chromaticity value
Figure 02_image025
: filter program
Figure 02_image001
: select weight value Q: chromaticity center point

為讓本發明之上述和其他目的、特徵、優點與實施例能更明顯易懂，所附圖式之說明如下： 第1圖係繪示依照本發明一第一實施例的影像白平衡方法的流程示意圖； 第2圖係繪示本發明之似白點區域及多個候選白點的示意圖； 第3圖係繪示依照本發明一第二實施例的影像白平衡方法的流程示意圖； 第4圖係繪示第3圖的影像白平衡方法之權重值調整步驟的流程示意圖；以及 第5圖係繪示依照本發明一第三實施例的影像白平衡系統的方塊示意圖。 In order to make the above and other objects, features, advantages and embodiments of the present invention more clearly understood, the accompanying drawings are described as follows: FIG. 1 is a schematic flowchart of an image white balance method according to a first embodiment of the present invention; FIG. 2 is a schematic diagram illustrating a white point-like region and a plurality of candidate white points according to the present invention; FIG. 3 is a schematic flowchart of an image white balance method according to a second embodiment of the present invention; FIG. 4 is a schematic flowchart illustrating a weight value adjustment step of the image white balance method of FIG. 3; and FIG. 5 is a block diagram illustrating an image white balance system according to a third embodiment of the present invention.

100:影像白平衡方法 100: Image white balance method

S1:第一色彩轉換步驟 S1: First color conversion step

S2:絕對差產生步驟 S2: Absolute difference generation step

S3:似白點區域篩選步驟 S3: Screening step of the white-like area

S4:候選白點保留步驟 S4: candidate white point retention step

S5:第二色彩轉換步驟 S5: Second color conversion step

110:第一影像 110: First image

120:轉換影像 120: Convert Image

130:似白點區域 130: White spot area

131:候選白點 131: Candidate White Point

140:第二影像 140:Second Image

321:色彩轉換程序 321: Color Conversion Program

322:運算程序 322: Operation program

323:篩選程序 323: Screener

W p :選取權重值 W p : select the weight value

Claims (12)

一種影像白平衡方法，用以轉換一第一影像為一第二影像，且該影像白平衡方法包含以下步驟： 一第一色彩轉換步驟，係驅動一處理單元根據一色彩轉換程序轉換對應一第一色彩格式之該第一影像為對應一第二色彩格式之一轉換影像，該轉換影像包含複數影像平均值及一最大亮度值； 一絕對差產生步驟，係驅動該處理單元根據一運算程序處理該些影像平均值而產生複數平均絕對差； 一似白點區域篩選步驟，係驅動該處理單元根據一篩選程序處理該些平均絕對差而從該轉換影像篩選出一似白點區域； 一候選白點保留步驟，係驅動該處理單元根據一選取權重值從該似白點區域中保留複數候選白點；以及 一第二色彩轉換步驟，係驅動該處理單元根據該些候選白點計算該最大亮度值以產生複數增益參數，然後根據該些增益參數轉換該第一影像為對應該第一色彩格式之該第二影像。 An image white balance method for converting a first image into a second image, and the image white balance method includes the following steps: A first color conversion step, driving a processing unit to convert the first image corresponding to a first color format into a converted image corresponding to a second color format according to a color conversion program, the converted image including the average value of the complex images and a maximum brightness value; an absolute difference generating step, driving the processing unit to process the average values of the images according to an operation program to generate a complex average absolute difference; a white-spot-like area screening step, which drives the processing unit to process the mean absolute differences according to a filtering procedure to filter out a white-spot-like area from the converted image; a candidate white point retaining step, which drives the processing unit to retain a plurality of candidate white points from the white point-like region according to a selection weight value; and A second color conversion step, which drives the processing unit to calculate the maximum luminance value according to the candidate white points to generate complex gain parameters, and then converts the first image into the first image corresponding to the first color format according to the gain parameters Two images. 如請求項1所述之影像白平衡方法，其中該運算程序包含該些影像平均值、該些平均絕對差、複數色度值、一水平座標、一垂直座標及一像素數目，該些影像平均值分別表示為
Figure 03_image003
與
Figure 03_image005
，該些平均絕對差分別表示為
Figure 03_image007
與
Figure 03_image009
，該些色度值分別表示為
Figure 03_image011
與
Figure 03_image013
，該水平座標表示為
Figure 03_image015
，該垂直座標表示為
Figure 03_image017
，該像素數目表示為
Figure 03_image019
且符合下式：
Figure 03_image021
；
Figure 03_image023
。 The image white balance method as claimed in claim 1, wherein the operation procedure includes the image average values, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate and a number of pixels, the image average values The values are expressed as
Figure 03_image003
and
Figure 03_image005
, these mean absolute differences are expressed as
Figure 03_image007
and
Figure 03_image009
, these chromaticity values are expressed as
Figure 03_image011
and
Figure 03_image013
, the horizontal coordinates are expressed as
Figure 03_image015
, the vertical coordinates are expressed as
Figure 03_image017
, the number of pixels is expressed as
Figure 03_image019
and conform to the following formula:
Figure 03_image021
;
Figure 03_image023
. 如請求項1所述之影像白平衡方法，其中該篩選程序包含該些影像平均值、該些平均絕對差、複數色度值、一水平座標、一垂直座標、一拓展權重值及一符號函數，該些影像平均值分別表示為
Figure 03_image003
與
Figure 03_image005
，該些平均絕對差分別表示為
Figure 03_image007
與
Figure 03_image009
，該些色度值分別表示為
Figure 03_image011
與
Figure 03_image013
，該水平座標表示為
Figure 03_image015
，該垂直座標表示為
Figure 03_image017
，該拓展權重值表示為
Figure 03_image025
，該符號函數表示為
Figure 03_image027
且符合下式：
Figure 03_image029
；
Figure 03_image031
。 The image white balance method of claim 1, wherein the screening procedure includes the image mean values, the mean absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, an extended weight value and a sign function , the average values of these images are expressed as
Figure 03_image003
and
Figure 03_image005
, these mean absolute differences are expressed as
Figure 03_image007
and
Figure 03_image009
, these chromaticity values are expressed as
Figure 03_image011
and
Figure 03_image013
, the horizontal coordinates are expressed as
Figure 03_image015
, the vertical coordinates are expressed as
Figure 03_image017
, the extended weight value is expressed as
Figure 03_image025
, the symbolic function is expressed as
Figure 03_image027
and conform to the following formula:
Figure 03_image029
;
Figure 03_image031
. 如請求項3所述之影像白平衡方法，更包含： 一權重值調整步驟，包含： 一第一調整步驟，係驅動該處理單元根據一亮度值比對程序調整該拓展權重值；及 一第二調整步驟，係驅動該處理單元根據一分數值比對程序調整該選取權重值； 其中，該處理單元根據已調整的該拓展權重值與已調整的該選取權重值重新執行該第一色彩轉換步驟、該絕對差產生步驟、該似白點區域篩選步驟、該候選白點保留步驟及該第二色彩轉換步驟而產生對應該第一色彩格式之已調整的該第二影像。 The image white balance method as described in claim 3, further comprising: A weight value adjustment step, including: a first adjustment step of driving the processing unit to adjust the extended weight value according to a luminance value comparison procedure; and a second adjustment step, driving the processing unit to adjust the selection weight value according to a score comparison procedure; Wherein, the processing unit re-executes the first color conversion step, the absolute difference generation step, the white-like-point region screening step, and the candidate white-point retention step according to the adjusted extension weight value and the adjusted selection weight value and the second color conversion step to generate the adjusted second image corresponding to the first color format. 如請求項4所述之影像白平衡方法，其中該亮度值比對程序包含該拓展權重值、一目標亮度值及一參考亮度值，該拓展權重值表示為
Figure 03_image025
，該目標亮度值表示為
Figure 03_image033
，該參考亮度值表示為
Figure 03_image035
且符合下式：
Figure 03_image037
。 The image white balance method of claim 4, wherein the luminance value comparison procedure includes the extended weight value, a target luminance value and a reference luminance value, and the extended weight value is expressed as
Figure 03_image025
, the target brightness value is expressed as
Figure 03_image033
, the reference luminance value is expressed as
Figure 03_image035
and conform to the following formula:
Figure 03_image037
. 如請求項4所述之影像白平衡方法，其中該分數值比對程序包含該選取權重值、一目標分數值及一參考分數值，該選取權重值表示為
Figure 03_image001
，該目標分數值表示為
Figure 03_image039
，該參考分數值表示為
Figure 03_image041
且符合下式：
Figure 03_image043
。 The image white balance method of claim 4, wherein the score comparison procedure includes the selection weight value, a target score value and a reference score value, and the selection weight value is expressed as
Figure 03_image001
, the target score value is expressed as
Figure 03_image039
, the reference score value is expressed as
Figure 03_image041
and conform to the following formula:
Figure 03_image043
. 一種影像白平衡系統，用以轉換一第一影像為一第二影像，且該影像白平衡系統包含： 一儲存單元，用以存取該第一影像、一色彩轉換程序、一運算程序、一篩選程序及一選取權重值；以及 一處理單元，連接該儲存單元，該處理單元經配置以實施包含以下步驟之操作： 一第一色彩轉換步驟，係根據該色彩轉換程序轉換對應一第一色彩格式之該第一影像為對應一第二色彩格式之一轉換影像，該轉換影像包含複數影像平均值及一最大亮度值； 一絕對差產生步驟，係根據該運算程序處理該些影像平均值而產生複數平均絕對差； 一似白點區域篩選步驟，係根據該篩選程序處理該些平均絕對差而從該轉換影像篩選出一似白點區域； 一候選白點保留步驟，係根據該選取權重值從該似白點區域中保留複數候選白點；及 一第二色彩轉換步驟，係根據該些候選白點計算該最大亮度值以產生複數增益參數，然後根據該些增益參數轉換該第一影像為對應該第一色彩格式之該第二影像。 An image white balance system for converting a first image into a second image, and the image white balance system includes: a storage unit for accessing the first image, a color conversion program, an operation program, a filtering program and a selection weight value; and A processing unit connected to the storage unit, the processing unit configured to perform operations including the following steps: a first color conversion step of converting the first image corresponding to a first color format into a converted image corresponding to a second color format according to the color conversion program, the converted image including an average value of complex images and a maximum luminance value ; an absolute difference generating step, processing the average values of the images according to the operation program to generate a complex average absolute difference; a white-spot-like area screening step, processing the mean absolute differences according to the screening procedure to filter out a white-spot-like area from the converted image; a candidate white point retaining step of retaining a plurality of candidate white points from the white point-like region according to the selection weight value; and A second color conversion step includes calculating the maximum luminance value according to the candidate white points to generate complex gain parameters, and then converting the first image into the second image corresponding to the first color format according to the gain parameters. 如請求項7所述之影像白平衡系統，其中該運算程序包含該些影像平均值、該些平均絕對差、複數色度值、一水平座標、一垂直座標及一像素數目，該些影像平均值分別表示為
Figure 03_image003
與
Figure 03_image005
，該些平均絕對差分別表示為
Figure 03_image007
與
Figure 03_image009
，該些色度值分別表示為
Figure 03_image011
與
Figure 03_image013
，該水平座標表示為
Figure 03_image015
，該垂直座標表示為
Figure 03_image017
，該像素數目表示為
Figure 03_image019
且符合下式：
Figure 03_image021
；
Figure 03_image023
。 The image white balance system as claimed in claim 7, wherein the operation procedure includes the image average values, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate and a number of pixels, the image average values The values are expressed as
Figure 03_image003
and
Figure 03_image005
, these mean absolute differences are expressed as
Figure 03_image007
and
Figure 03_image009
, these chromaticity values are expressed as
Figure 03_image011
and
Figure 03_image013
, the horizontal coordinates are expressed as
Figure 03_image015
, the vertical coordinates are expressed as
Figure 03_image017
, the number of pixels is expressed as
Figure 03_image019
and conform to the following formula:
Figure 03_image021
;
Figure 03_image023
. 如請求項7所述之影像白平衡系統，其中該篩選程序包含該些影像平均值、該些平均絕對差、複數色度值、一水平座標、一垂直座標、一拓展權重值及一符號函數，該些影像平均值分別表示為
Figure 03_image003
與
Figure 03_image005
，該些平均絕對差分別表示為
Figure 03_image007
與
Figure 03_image009
，該些色度值分別表示為
Figure 03_image011
與
Figure 03_image013
，該水平座標表示為
Figure 03_image015
，該垂直座標表示為
Figure 03_image017
，該拓展權重值表示為
Figure 03_image025
，該符號函數表示為
Figure 03_image027
且符合下式：
Figure 03_image029
；
Figure 03_image031
。 The image white balance system of claim 7, wherein the screening procedure includes the image averages, the average absolute differences, complex chromaticity values, a horizontal coordinate, a vertical coordinate, an extended weight value, and a sign function , the average values of these images are expressed as
Figure 03_image003
and
Figure 03_image005
, these mean absolute differences are expressed as
Figure 03_image007
and
Figure 03_image009
, these chromaticity values are expressed as
Figure 03_image011
and
Figure 03_image013
, the horizontal coordinates are expressed as
Figure 03_image015
, the vertical coordinates are expressed as
Figure 03_image017
, the extended weight value is expressed as
Figure 03_image025
, the symbolic function is expressed as
Figure 03_image027
and conform to the following formula:
Figure 03_image029
;
Figure 03_image031
. 如請求項9所述之影像白平衡系統，其中該處理單元經配置以實施更包含以下步驟之操作： 一權重值調整步驟，包含： 一第一調整步驟，係根據一亮度值比對程序調整該拓展權重值；及 一第二調整步驟，係根據一分數值比對程序調整該選取權重值； 其中，該處理單元根據已調整的該拓展權重值與已調整的該選取權重值重新執行該第一色彩轉換步驟、該絕對差產生步驟、該似白點區域篩選步驟、該候選白點保留步驟及該第二色彩轉換步驟而產生對應該第一色彩格式已調整的該第二影像。 The image white balance system of claim 9, wherein the processing unit is configured to perform operations further comprising the steps of: A weight value adjustment step, including: a first adjustment step of adjusting the extended weight value according to a luminance value comparison procedure; and a second adjustment step of adjusting the selection weight value according to a score comparison procedure; Wherein, the processing unit re-executes the first color conversion step, the absolute difference generation step, the white-like-point region screening step, and the candidate white-point retention step according to the adjusted extension weight value and the adjusted selection weight value and the second color conversion step to generate the second image adjusted corresponding to the first color format. 如請求項10所述之影像白平衡系統，其中該亮度值比對程序包含該拓展權重值、一目標亮度值及一參考亮度值，該拓展權重值表示為
Figure 03_image025
，該目標亮度值表示為
Figure 03_image033
，該參考亮度值表示為
Figure 03_image035
且符合下式：
Figure 03_image037
。 The image white balance system of claim 10, wherein the luminance value comparison procedure includes the extended weight value, a target luminance value and a reference luminance value, and the extended weight value is expressed as
Figure 03_image025
, the target brightness value is expressed as
Figure 03_image033
, the reference luminance value is expressed as
Figure 03_image035
and conform to the following formula:
Figure 03_image037
. 如請求項10所述之影像白平衡系統，其中該分數值比對程序包含該選取權重值、一目標分數值及一參考分數值，該選取權重值表示為
Figure 03_image001
，該目標分數值表示為
Figure 03_image039
，該參考分數值表示為
Figure 03_image041
且符合下式：
Figure 03_image043
。 The image white balance system of claim 10, wherein the score comparison procedure includes the selection weight value, a target score value and a reference score value, and the selection weight value is expressed as
Figure 03_image001
, the target score value is expressed as
Figure 03_image039
, the reference score value is expressed as
Figure 03_image041
and conform to the following formula:
Figure 03_image043
.
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Citations (4)

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Publication number Priority date Publication date Assignee Title
TW201340727A (en) * 2012-03-19 2013-10-01 Altek Corp White balance method and apparatus thereof
CN104618703A (en) * 2015-02-09 2015-05-13 傅邓文 White balance adjusting method
CN107135384A (en) * 2017-05-19 2017-09-05 中国科学院深圳先进技术研究院 White balance adjusting method, device, image processing terminal and storage medium
US20190253683A1 (en) * 2018-02-09 2019-08-15 Shanghai Xiaoyi Technology Co., Ltd. White balance parameter determination method and white balance adjustment method, device, and storage medium thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW201340727A (en) * 2012-03-19 2013-10-01 Altek Corp White balance method and apparatus thereof
CN104618703A (en) * 2015-02-09 2015-05-13 傅邓文 White balance adjusting method
CN107135384A (en) * 2017-05-19 2017-09-05 中国科学院深圳先进技术研究院 White balance adjusting method, device, image processing terminal and storage medium
US20190253683A1 (en) * 2018-02-09 2019-08-15 Shanghai Xiaoyi Technology Co., Ltd. White balance parameter determination method and white balance adjustment method, device, and storage medium thereof

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