CN100571407C

CN100571407C - White balance control method

Info

Publication number: CN100571407C
Application number: CNB2005101305489A
Authority: CN
Inventors: 林文国
Original assignee: Lianyang Semiconductor Co ltd
Current assignee: LIANYANG SEMICONDUCTOR CO Ltd
Priority date: 2005-12-14
Filing date: 2005-12-14
Publication date: 2009-12-16
Anticipated expiration: 2025-12-14
Also published as: CN1984348A

Abstract

The invention discloses a white balance control method, which firstly sets an initial white balance setting. Then, an image is obtained according to the white balance setting, and the average red, green and blue values of the whole image and the white pixel are obtained. The white balance information is calculated using the average rgb values of both the full image and the white pixel, respectively. Then, the red, green and blue white balance information of the full image and the white pixel is used to determine whether the current white balance state is in accordance with the actual ambient brightness. If the determined result indicates that a new white balance state needs to be selected, a new white balance setting is set. Finally, the process returns to the step of acquiring a new image and executing the subsequent steps. The invention can be applied to an image processing device or method.

Description

Method for controlling white balance

Technical field

The present invention relates to a kind of automatic white balance adjustment method, particularly a kind of light source according to different-colour is adjusted the automatic white balance adjustment method of white balance.The present invention can be applicable on image processor or the method.

Background technology

(human visual system HVS) for the adaptation of prismy color change, is that the mankind have a specific character to the human visual system, and this specific character is perception one white surface and it is used as pure white under the light source condition of different-colour.In order to imitate human visual system's adaptation, when all digitized video sense control assemblies will be obtained digitized video, must have method for controlling white balance and realize human digitized video at the similar image that really perceives at that moment.

Fig. 1 is the flow chart of steps of the method for controlling white balance of a traditional use total image, at first, sets an initial white balance and sets, shown in step S10.Secondly, shown in step S12, obtain an image according to this white balance setting.Shown in step S14, obtain the average RGB value of total image.Shown in step S16, use the average RGB value of total image to calculate white balance information.

Shown in step S18, use white balance information to decide the light and shade situation of current white balance state around whether realistic.Shown in step S20, set if need not change current white balance, then program is back to step S12 and obtains a new image, otherwise execution in step S22 then.Shown in step S22, if showing, the result who is determined need select a new white balance state, then set a new white balance and set.At last, program is back to the step that obtains a new image and carries out step thereafter.

Fig. 2 is the flow chart of steps of the method for controlling white balance of another traditional use white pixel, at first, sets an initial white balance and sets, shown in step S40.Secondly, shown in step S42, obtain an image according to this white balance setting.Shown in step S44, find out the white pixel in the image.Shown in step S46, obtain the average RGB value of white pixel.Shown in step S48, use the average RGB value of white pixel to calculate white balance information.

Shown in step S50, use white balance information to decide the light and shade situation of current white balance state around whether realistic.Shown in step S52, set if need not change current white balance, then program is back to step S42 and obtains a new image, otherwise execution in step S54 then.Shown in step S54, if showing, the result who is determined need select a new white balance state, then set a new white balance and set.At last, program is back to the step that obtains a new image and carries out step thereafter.

Though above-mentioned two method for controlling white balance of commonly using are widely used, they distinctly have some shortcomings.In first method, when obtained scenery, when for example being the scenery in the setting sun, forest or blue sky, in these scenery, has the color of some master controls, and when the white balance information of using the total image RGB decides current white balance state, can cause incorrect white balance to judge.The result can make image be corrected and have identical average RGB value and seem nature.In the second approach, when the white pixel number that is found does not surpass the certain ratio of overall number of pixels, and when the white balance information of using the white pixel RGB decides current white balance state, be difficult to obtain correct result.

Summary of the invention

The objective of the invention is provides a kind of method for controlling white balance for addressing the above problem, its integrate traditional control method in two and add the program that strengthens and form a kind of more perfect and more can accurately react around the method for controlling white balance of light and shade situation.

Method for controlling white balance provided by the invention is at first set an initial white balance and is set.Secondly, obtain an image, obtain both average RGB values of total image and white pixel according to this white balance setting.Use both average RGB values of total image and white pixel to calculate white balance information respectively.Again secondly, use the white balance information of total image and both RGBs of white pixel to decide the light and shade situation of current white balance state around whether realistic.Need select a new white balance state if the result who is determined shows, then set a new white balance and set.At last, program is back to step and the execution step thereafter that obtains a new image.

The present invention is described in detail below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the flow chart of step of the method for controlling white balance of a traditional use total image;

Fig. 2 is the flow chart of step of the method for controlling white balance of another traditional use white pixel;

Fig. 3 is the flow chart of the step of method for controlling white balance of the present invention;

Fig. 4 A and Fig. 4 B are the flow charts of step of a preferred embodiment of method for controlling white balance of the present invention;

Fig. 5 system illustrates the skeleton diagram of the white balance state of a control of difference;

Fig. 6 A and Fig. 6 B are the flow charts of a preferred version of the thin portion of determination procedure content.

Embodiment

The present invention is a kind of method for controlling white balance, control method shown in its integration map 1 and Fig. 2 and the program that add to strengthen and form a kind of more perfect and more can accurately react around the novel method for controlling white balance of light and shade situation.

Fig. 3 is the flow chart of the step of method for controlling white balance of the present invention, at first, sets an initial white balance and sets, shown in step S110.

Secondly, shown in step S112, obtain an image according to this white balance setting.Shown in step S114, S144 and S146, obtain both average RGB values of total image and white pixel.Shown in step S116 and S148, use both average RGB values of total image and white pixel to calculate white balance information respectively.

Again secondly, shown in step S118, use the white balance information of total image and both RGBs of white pixel to decide the light and shade situation of current white balance state around whether realistic.Shown in step S120, set if need not change current white balance, then program is back to step S112, otherwise execution in step S122 then.Shown in step S122, if showing, the result who is determined need select a new white balance state, then set a new white balance and set.

At last, program is back to step and the execution step thereafter that obtains a new image.

Fig. 4 is the flow chart of step of a preferred embodiment of method for controlling white balance of the present invention, and its whole control program is divided into four key steps.

Shown in step Step I, the method for controlling white balance of this preferred embodiment is to set initial state for.In regular turn shown in step S200, S202, S204 and S206, these initial states comprise selects several white balance state of a controls n, select several white balance situation bias voltages for white balance state of a control Status 1 to Status n, select an initial white balance state of a control Status S, and load one group of white balance situation bias voltage for white balance state of a control Status S.The white balance situation bias voltage of these white balance state of a controls Status 1 to Status n is obtained according to empirical value.

Fig. 5 is the skeleton diagram that illustrates the white balance state of a control of difference.As shown in Figure 5, the number of selected white balance state of a control is n, and this is that expression has the white balance setting of n state with on every side the light and shade situation of reaction by the low paramount colour temperature of colour temperature.For the white balance state of a control Status (n-1) of difference to the situation bias voltage of the difference of Status n be to be expressed as T _{(n-1), n}, and the situation bias voltage of the difference of Status n to Status (n-1) is to be expressed as T _{N, (n-1)}

Shown in step Step II, obtain an image according to a current white balance state of a control, shown in step S208.Have two groups of white balance information in this as shown in the figure.Afterwards, obtain information, reach shown in the step as described below for decision white balance state of a control institute palpus.Shown in step S210, first group of white balance information obtained by total image, comprises average total image RGB value R ₁, G ₁And B ₁Shown in step S212, first group of white balance acquisition value comprises the first red acquisition value Rg ₁And the first blue acquisition value Bg ₁Shown in step S214, average total image legibility Y.White balance acquisition value Rg ₁And Bg ₁Respectively by Rg ₁=G ₁/ R ₁And Bg ₁=G ₁/ B ₁Institute is given.And legibility Y is by Y=C ₁XR ₁+ C ₂XG ₁+ C ₃XB ₁Institute is given, wherein C ₁+ C ₂+ C ₃=1.

Shown in step S220 and S222, second group of white balance information obtained by the white pixel in the image, comprises average white pixel RGB value R ₂, G ₂And B ₂Shown in step S224, second group of white balance acquisition value comprises the second red acquisition value Rg ₂And the second blue acquisition value Bg ₂Shown in step S226, the number C of white pixel _WBWhite balance acquisition value Rg ₂And Bg ₂Respectively by Rg ₂=G ₂/ R ₂And Bg ₂=G ₂/ B ₂Institute is given.

Shown in step Step III, the white balance information that is obtained by step Step II is with deciding current white balance state whether can react actual light and shade situation on every side, shown in step S250.Fig. 6 is the flow chart of a preferred version of the thin portion of the determination procedure among step S250 content, with the number C of white pixel _WBWith a situation bias voltage Th _cCompare, shown in step S300.If the number C of white pixel _WBSurpass situation bias voltage Th _c, then program execution in step S310 uses the white balance information of white pixel RGB to decide white balance to set.Otherwise, if the number C of white pixel _WBDo not surpass situation bias voltage Th _c, then program execution in step S400 uses the white balance information of total image RGB to decide white balance to set.Use this determination procedure can guarantee in an image, to have enough and can react light and shade situation on every side by detected white pixel number.

Shown in step S310, if do not have enough can detected white pixel number and present state Status S be not equal to n (not being to be positioned at high state), program execution in step S320 then is with second group of white balance acquisition value Rg ₂And Bg ₂With a situation bias voltage T2 _{S, (s+1)}Compare.Shown in step S330, if this relatively determines program execution in step S510 then; Otherwise program execution in step S340 then.Shown in step S510, white balance state of a control Status S changes over S=S+1 and a flag signals Flag sets 1 for to indicate the white balance state of a control to change.If step S330's relatively is that undetermined or present state Status S equals n, then program execution in step S340.Shown in step S340, check whether Status S equals 1, if Status S is not equal to 1, program execution in step S350 then.Shown in step S350, with second group of white balance acquisition value Rg ₂And Bg ₂With a situation bias voltage T2 _{S, (s-1)}Compare.Shown in step S360, relatively determine as if above-mentioned, then program execution in step S520; Otherwise program execution in step S530 then.Shown in step S520, white balance state of a control Status S changes over S=S-1 and flag signals Flag sets 1 for.If step S360's relatively is that undetermined or present state Status S equals 1, then program execution in step S530.Shown in step S530, current white balance is set and will do not changed, that is S=S and Flag=0.

White balance acquisition value Rg ₂And Bg ₂With situation bias voltage T2 _{S, (s+1)}One real example of comparing is given Rg ₂＞=1.00 and Bg ₂＜=1.00, when around the light and shade situation demonstrate the situation of being reacted and have higher colour temperature than current white balance state of a control Status S, then above-mentionedly relatively determine.In addition, Rg ₂And Bg ₂With situation bias voltage T2 _{S, (s-1)}One real example of comparing is given Rg ₂＜=1.00 and Bg ₂＞=1.00, when around the light and shade situation demonstrate the situation of being reacted and have lower colour temperature than current white balance state of a control Status S, then above-mentionedly relatively determine.In addition, second group of white balance acquisition value Rg ₂And Bg ₂And the comparison between the situation bias voltage is stated more than not bright for restriction, can also select different comparisons or other situation bias voltage for use.

In obtained image, do not have under the situation of enough white pixel numbers, use the white balance information of total image RGB to decide white balance to set, at first, shown in the step S400 of Fig. 6, with an average total image legibility Y and a situation bias voltage Th _YCheck with verification legibility Y whether have effective color information enough greatly, if legibility Y is not more than situation bias voltage Th _YProgram execution in step S530 then, white balance is set and will do not changed and Flag is set as 0; Otherwise program execution in step S410 then.Shown in step S410, if legibility Y is greater than situation bias voltage Th _YAnd present white balance state of a control Status S is not equal to n, then program execution in step S420.Shown in step S420, with first group of white balance acquisition value Rg ₁And Bg ₁With a situation bias voltage T1 _{S, (s+1)}Compare.Shown in step S430, if this relatively determines program execution in step S510 then; Otherwise program execution in step S440 then.Shown in step S510, white balance state of a control S=S+1 and flag signals Flag set 1 for.If step S430's relatively is that undetermined or present state Status S equals n, then program execution in step S440.Shown in step S440, check whether Status S equals 1, if Status S is not equal to 1, program execution in step S450 then.Shown in step S450, with first group of white balance acquisition value Rg ₁And Bg ₁With a situation bias voltage T1 _{S, (s-1)}Compare.Shown in step S460, relatively determine as if above-mentioned, then program execution in step S520; Otherwise program execution in step S530 then.Shown in step S520, white balance state of a control Status S changes over S=S-1 and flag signals Flag sets 1 for.If step S460's relatively is that undetermined or present state Status S equals 1, then program execution in step S530.

White balance acquisition value Rg ₁And Bg ₁With situation bias voltage T2 _{S, (s+1)}One real example of comparing is given [Rg ₁＜2.5 and Bg ₁＞0.5 and (Rg ₁＞=1.0 or Bg ₁＜1.0)].On the other hand, Rg ₁And Bg ₁With situation bias voltage T2 _{S, (s-1)}One real example of comparing is given [Rg ₁＞0.5 and Bg ₁＜2.5 and (Rg ₁＜1.0 or Bg ₁＞=1.0)].Above-mentioned these relatively can be guaranteed to reduce the effect that the color of some master control causes in the image and have influence on status accuracy relatively.In addition, first group white balance acquisition value and the comparison between the situation bias voltage are stated more than not bright for restriction, can also select different comparisons or other situation bias voltage for use.

Shown in the step StepIV of Fig. 4, after the white balance state of a control, shown in step S260, set if need change current white balance, then program execution in step S270; Otherwise set if need not change current white balance, then program is back to step Step II.Shown in step S270, set a new white balance state.Shown in step S280, for new one group of white balance situation of white balance state load bias voltage, and program is back to step Step II.

In sum, can correctly determine the light and shade situation on every side of different-colour, so can accurately adjust white balance according to light and shade situation on every side according to the present invention.

Claims

1. A white balance control method, comprising the following steps:

Select several white balance control states Status 1 to Status n to reflect the surrounding light and dark conditions from low color temperature to high color temperature;

For the white balance control states Status 1 to Status n select several white balance status biases;

Select an initial white balance control state from several white balance control states;

For the initial white balance control state, load a set of white balance status bias;

Obtain an image according to the initial white balance control state or a current white balance control state denoted as Status S;

Obtain a first white balance information through the image, including the average full image red, green and blue values, the first group of white balance obtained values and brightness;

The second set of white balance information obtained through the image is obtained from the white pixels in the image, including the average white pixel red, green and blue values, the second set of white balance values and the number of white pixels;

According to the first and second sets of white balance information, it is determined whether the current white balance state conforms to the above-mentioned actual surrounding light and dark conditions, and a decision value is obtained;

Obtaining another image when the above-mentioned determination value shows that the current white balance control state does not need to be changed; and

When the above decision value indicates that the current white balance control state needs to be changed, a new white balance control state is set, a new white balance state bias of the new white balance control state is loaded, and a new image is obtained.

2. The white balance control method as claimed in claim 1, wherein the step of determining whether the current white balance state conforms to the above-mentioned actual surrounding light and dark conditions further comprises the following steps:

comparing the number of white pixels with a first state bias;

When the number of white pixels exceeds the first condition bias voltage, the determination value is obtained according to the second set of white balance information;

When the current white balance control status Status S is not equal to Status n, compare the second set of white balance obtained values with the white balance status bias voltage corresponding to the white balance control status Status S and Status S+1;

When the comparison between the second group of white balance obtained values and the white balance status bias corresponding to the white balance control status Status S and Status S+1 is confirmed, then change the white balance control status Status S to Status S+1 And set a flag signal Flag to 1;

When the comparison of the second group of white balance obtained values with the white balance status bias corresponding to the white balance control status Status S and Status S+1 is undetermined or Status S is equal to n, then check whether Status S is equal to 1;

When Status S is not equal to 1, then compare the second set of white balance obtained values with the white balance status bias voltage corresponding to the white balance control status Status S and Status S-1; and

When the comparison of the second set of white balance obtained values with the white balance status bias corresponding to the white balance control status Status S and Status S-1 is confirmed, then the white balance control status Status S is changed to StatusS-1 and Set the flag signal Flag to 1.

3. The white balance control method as claimed in claim 2, wherein, when comparing the white balance obtained value of the second group with the white balance state bias voltage corresponding to the white balance control states Status S and Status S+1 , a red obtained value of the second group of white balance obtained values is not less than 1, and a blue obtained value of the second group of white balance obtained values is not greater than 1.

4. The white balance control method as claimed in claim 2, wherein, when comparing the second group of white balance obtained values with the white balance status bias voltage corresponding to the white balance control states Status S and Status S-1 , the red obtained value of the second group of white balance obtained values is not greater than 1, and the blue obtained value of the second group of white balance obtained values is not less than 1.

5. The white balance control method as claimed in claim 2, wherein the step of determining whether the current white balance state conforms to the above-mentioned actual surrounding light and dark conditions further comprises the following steps:

When the number of white pixels does not exceed the first condition bias voltage, the determination value is obtained according to the first set of white balance information;

Checking the photopicity of the first set of white balance information with a second condition bias to verify whether the photopicity is large enough to have valid color information;

When the brightness is greater than the second status bias voltage and the current white balance control state Status S is not equal to n, then the first group of white balance obtained values and the corresponding white balance control state Status S and StatusS+1 white Balance condition bias comparison;

When the comparison of the white balance obtained value of the first group with the white balance status bias corresponding to the white balance control status Status S and StatusS+1 is confirmed, the white balance control status Status S is changed to StatusS+1 and Set the flag signal Flag to 1;

When the comparison of the white balance obtained value of the first group with the white balance status bias corresponding to the white balance control status Status S and StatusS+1 is undetermined or Status S is equal to n, then check whether Status S is equal to 1;

When Status S is not equal to 1, compare the white balance obtained value of the first group with the white balance status bias voltage corresponding to the white balance control state Status S and Status S-1; and

When the comparison of the first set of white balance obtained values with the white balance status bias corresponding to the white balance control status Status S-1 and Status S is confirmed, then the white balance control status Status S is changed to Status S-1 and Set the flag signal Flag to 1.

6. The white balance control method as claimed in claim 5, wherein, when comparing the first group of white balance obtained values with the white balance state bias voltage corresponding to the white balance control states Status S and Status S+1, A red obtained value of the first group of white balance obtained values is less than 2.5 and not less than 1, and a blue obtained value of the first group of white balance obtained values is greater than 0.5 and less than 1.

7. The white balance control method as claimed in claim 5, wherein, when comparing the obtained white balance value of the first group with the white balance state bias voltage corresponding to the white balance control states Status S and Status S-1 , the red obtained value of the first group of white balance obtained values is greater than 0.5 and less than 1, and the blue obtained value of the first group of white balance obtained values is less than 2.5 and not less than 1.