JP2952518B2 - Imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus provided with a white balance adjustment unit suitable for close-up photography.

[Conventional technology]

For imaging devices such as video cameras and electronic still cameras,
A white balance adjusting means is provided so that the reproduced white becomes correct white. On the other hand, a large number of image pickup apparatuses equipped with a macro lens that enables close-up photographing have come to be seen.

FIG. 12 is a block diagram of a conventional imaging device using a macro lens. In the figure, 1 is a macro lens, 2 is CC
An image sensor that performs photoelectric conversion such as D, a luminance signal processing unit that derives a luminance signal Y from an output of the image sensor 2, a low-frequency component Y _{L of a} luminance signal, a red signal R, and a blue signal from the output of the image sensor 2. Chroma signal processing units for deriving B, 5 and 6, R gain control units and B gain control units for changing the signal levels of the output signals R and B of the chroma signal processing unit 4, respectively; output Y _L and R, an output R ', B' color difference signals R from the B gain control section 5, 6
A matrix amplifier 9 for deriving -Y and BY is used to modulate the output Y of the luminance signal processing unit 3 and the outputs RY and BY of the matrix amplifiers 7 and 8 into prescribed signals. A modulation processing unit that enables recording on a recording medium or the like and image output to a monitor. 10 and 11 are the output R-Y of the matrix amplifiers 7 and 8,
An averaging section 21 for averaging several screens by integrating BY, etc., 21 derives a control voltage appropriate for white balance from the outputs of the averaging sections 10 and 11, and outputs an R, B gain control section. This is a control voltage deriving unit that controls 5,6.

 Hereinafter, the operation of the conventional example will be described with reference to FIG.

In close-up photography, a subject image formed on the image sensor 2 through a macro lens is converted into an electric signal. The output signal from the image sensor 2 is sent to the luminance signal processing unit 3 and the chroma signal processing unit 4, and the luminance signal processing unit 3 outputs the luminance signal Y, and the chroma signal processing unit 4 outputs the low frequency component Y _{L of the} luminance signal. A red signal R and a blue signal B are derived. Here, Y _L is Y _L = 0.30R + 0.59G + 0.11B
Is a signal in which red: R, blue: B, and green: G are mixed. Of the outputs derived by the chroma signal processing unit 4, R and B are R
The signals are sent to gain control units 5 and B gain control unit 6, where their signal levels are changed for white balance adjustment, and signals R 'and B' are derived. The outputs Y _L of the chroma signal processing unit 4 and the outputs R ′ and B ′ of the R and B gain control units 5 and 6 are matrix
The color difference signals RY and BY are sent to the amplifiers 7 and 8 (where RY = 0.70R-0.59G-0.11B BY = 0.8
9B-0.59G-0.30R).

The signals Y, RY, and BY are sent to the modulation processing unit 9, where they are modulated and output in a prescribed signal form so as to enable recording on a recording medium or the like, or output to a monitor.

On the other hand, the RY and BY signals output from the matrix amplifiers 7 and 8 are also sent to averaging units 10 and 11 to derive an average position for one or more screens. Then, the control voltage deriving unit 21 derives control voltages to the R and B gain control units 5 and 6 so that the average signal level becomes 0 level (that is, R = G = B), thereby adjusting the white balance. It is carried out.

[Problems to be solved by the invention]

However, in the above-described conventional example, when a high-saturation subject, which tends to be close-up shooting, is largely displayed in the center of the screen during close-up shooting using a macro lens, there is a problem that it is difficult to perform shooting with suitable white balance adjustment. .

Also, in the case of the peak method in which a luminance signal is sampled and used for white balance adjustment by sampling a color difference signal of a portion having a certain level or more without using the average ground of the color difference signal as in the conventional example, the white balance when using a macro lens is used. Although the deterioration is considered to be small, the white balance during normal shooting (when the macro lens is not used) is generally not good, so this is not a solution.

The present invention has been made under such circumstances, and it is an object of the present invention to provide an image pickup apparatus that can perform a good white balance adjustment even during close-up image pickup.

[Means for solving the problem]

In the present invention, in order to achieve the above object, the imaging device is configured as in the following (1) and (2).

(1) A first method of performing white balance adjustment based on an image sensor and a signal including a signal obtained by averaging the output of the image sensor.
White balance adjustment means, and a second white balance adjustment means for performing white balance adjustment based on an output signal of the image sensor whose luminance signal level is within a predetermined range,
Detecting means for detecting the execution of close-up photography; and selecting means for preferentially selecting the second white balance adjusting means to perform white balance adjustment when the detection means detects execution of close-up photography. Imaging device.

(2) an image sensor, a white balance adjusting unit that performs white balance adjustment using an output signal of the image device, a detecting unit that detects execution of close-up shooting, and a case where the detecting unit detects execution of close-up shooting. An image pickup apparatus comprising: a white balance adjustment unit configured to perform white balance adjustment based on an output signal of the image sensor whose luminance signal level is within a predetermined range.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 is a block diagram of an "imaging device" according to a first embodiment of the present invention.

In FIG. 1, reference numerals 1 to 11 are the same blocks as those in the conventional example shown in FIG. 12 is an A / D (analog-digital) converter, 13 is a microcomputer system (hereinafter referred to as a microcomputer), 14 is a D / A (digital-analog) converter, and 15 is a photometric sensor that measures the brightness of external light. is there. FIG. 2 is a flowchart showing the operation of the microcomputer 13 in FIG. 1, and FIGS. 3 and 4 are a configuration diagram and a timing chart for explaining the operation of the averaging units 10 and 11.

FIG. 5 is a diagram for explaining a limited range of the white balance control voltage in this embodiment.

Hereinafter, the first embodiment will be described with reference to FIGS.

First, in FIG. 1, the operations of 1 to 11 are the same as the conventional example, but the operations of the averaging units 10 and 11 are shown in FIGS.
This will be described with reference to the drawings.

The RY signal is inputted to the input side of the switch 101 in FIG. 3 in the case of the block 10 and the BY signal in the case of the block 11. At this time, switch 101
4 is closed when INTE in FIG. 4 is at a high level, and is open when it is at a low level. Only when closed, each signal is connected to a resistor 102, a capacitor 104, a reference voltage source 105, and a differential amplifier 10.
It is input to an integrating circuit consisting of six. On the other hand, switch 103
Is closed when RESET in FIG. 4 is at a high level, so that the charge stored in the capacitor 104 is discharged during that period.

As a result, the outputs of the averaging units 10 and 11 become SIGNA of FIG.
The waveform shown in FIG. 4A is obtained, and the output of the SAMPLE shown in FIG.
The average level in one screen of the Y, BY signal can be detected. VD is a vertical drive signal.

The respective average values obtained as described above are input to the microcomputer 13 via the A / D converter 12, and the microcomputer 13 derives a white balance control voltage based on these values. The operation will be described below with reference to FIGS. 2 and 5.

First, as shown in the second step 1, a predetermined value is set as α, as an initial value in the microcomputer memory.
β, A, B, C, D, X, Y, L _O , R _C , B _C , and F _O. Next, as shown in step 2, the output L _S of the photometric sensor 15 is set to A / D The data is read through the converter 12 and divided by a constant L _O to obtain L (see step 3). Here, L _O is a value indicating the average brightness of outdoor light. If the obtained L is 1 or more, L is fixed to 1 (steps 4 and 5),
If L <1, go directly to step 6 from step 4.
Next, the outputs of the averaging unit (RY) _S and (BY) _S are read (step 6), and if (RY) _S <-α, _RC = _RC +1 (RY) _S If> α, R _C = R _C −1 (BY) _S <−β, B _C = B _C +1 (BY) If _S > β, B _C = B _C −1, otherwise The control voltages R _C and B _C are set as they are, that is, as initial values (steps 7-14). Here, if the R gain control voltage R _C has a large value, the gain of the R gain control unit 5 increases and the R signal level increases, and if the B gain control voltage B _C has a large value, the B gain control voltage B _C increases. It is set so that the gain of the control unit 6 decreases and the B signal level decreases. In addition, the initial values of the control voltages R _C and B _C are set to intermediate values of respective possible ranges in order to quickly determine the final outputs of R _C and B _C. After setting the values of the control voltages R _C and B _C as described above, it is detected whether or not the present imaging apparatus is in the macro lens use state (step 15).

Then, if the macro lens is not in use, the limited range a, b, c, d of the control voltage is changed to the initial values A, B,
C and D. On the other hand, if the macro lens use, firstly derives the flicker component F of the external light from the output of the photometry sensor 15 in step 17, compared with the reference value F _O, F <F _O a long if not flicker light source, F ≧ F _O a long if the flicker light source, that is regarded as a fluorescent lamp.

Therefore, if F <F _O , a = (X−A) × L + Ab = (B−X) × L + Xc = (C−Y) × L + Y d = (Y−D) × L + D, and (step 18) see FIG. 5), F ≧ F _O if a = X, b = B, c = Y, is set to d = D (step 19). This is the operation in step 20-27 is a constant to limit the scope of control voltage R _C, each of the values of B _C can take. That is, if R _C ≧ a is NO, then R _C = a If R _C ≦ b is NO, then R _C = b B _C ≧ c, then B _C = c B _C ≦ d, then B _C = d. Thus, the control voltage limit range enclosed by □ klmn shown in FIG. 5 can be set.

The control voltages R _C and B _C obtained in this manner are converted to a D / A converter 14.
To the R and B gain control units 5 and 6 to change the level of each color difference signal, and based on the changed output, step 2
By performing the operation of −28, white balance adjustment can be suitably performed.

Now, the features of the first embodiment will be described in more detail with reference to FIG.

In this embodiment, whether the macro lens is in use or not is detected in step 15 in FIG. 2. If not, the limited range of the control voltage is within □ klmn in FIG. The values of _C and B _C are set (step 16).

On the other hand, in the case of using the macro lens, it is assumed that a high chroma subject often occupies most of the screen.
The output of the averaging unit is strongly affected by the object color, and the white balance may be greatly shifted. Therefore, in the case of using the macro lens, the limited range of the control voltage R _C and B _C is further narrowed, and the position of the limited range is set to an optimum position based on information from other sensors and the like. In this embodiment, first, in step 17, it is detected whether or not the light source is a fluorescent lamp. If the light source is a fluorescent lamp, the limited range is set to □ oqms. Also, if it is a non-flicker light source, it is determined whether the light is outdoor light or indoor light by the brightness L _{S of the} external light, If so, it is assumed that the light source is completely outdoor light and a bluish light source is assumed, and the control voltage limited range is □ orlq in FIG. On the other hand, for example, if L ≦ 0.001, the limited range is almost □ osn
becomes p. In this case, since the light source is considerably dark, the limited range is set on the assumption that the light source is reddish assuming that the light is room light. In addition, tungsten light or the like generally takes on a reddish color as it gets darker, and thus it is considered that the setting of this limited range is well matched. If L is an intermediate value, the limited range is □ osn with L = 0.001 → L = 1
p → □ orlq.

As described above, when the macro lens is used, the limited range of the control voltage is made narrower by the information (brightness of external light and the amount of flicker) from the photometric sensor 15 so that the white balance can be obtained without being strongly affected by the object color. Adjustments can be made.

In the above embodiment, a warning device may be provided to alert the photographer when the control voltages R _C and B _C have reached the limit of the limited range.

 FIG. 6 is a block diagram of a second embodiment of the present invention.

In FIG. 6, 1 to 15 are the same blocks as in the first embodiment, and 16 is an averaging unit having the same configuration as 10 and 11. The operation of the second embodiment is described above, and the operation of the blocks 1 to 11, 14, and 15 is the same as that of the first embodiment.

In this embodiment, signals R-Y average values to be input to the microcomputer 13, B-Y mean values, other photometric sensor output, the Y _L output of the chroma signal processing unit 4 to the averaging unit 16 averages the signals A Input to the microcomputer 13 via the / D converter 12. The microcomputer _{13, Y L, R-Y} , B-Y each averaged signal Y _S of, (R-Y) _S,
(BY) R, G, B signals are derived from _S. For example, the following operation is performed.

_{R = (R-Y) S} + Y LS = R B = (B-Y) S + Y LS = B G = (Y LS -0.30 · R-0.11 · B) /0.59 R derived in this way, B, The ratios of R and G, B and G are derived from the G signal, and the control voltages R _C and B _C at which the respective ratios R / G and B / G are 1 respectively.
Is calculated. Then, the calculated control voltages R _C and B _C are sent to the R gain control unit 5 and the B gain control unit 6 via the D / A converter 14 to perform white balance adjustment. Also in this embodiment, the use of the macro lens 1 is detected, and when it is detected, the light amount value obtained from the output of the photometric sensor 15 is applied to the control voltages R _C and B _C as in the first embodiment. and further adding a limitation on the scope of the control voltage R _C, B _B from the flicker amount values. Thereby, a suitable white balance adjustment can be performed even when the macro lens is used. At the same time, in this embodiment, since the control voltages R _C and B _C can be immediately calculated from the (R−Y) _S , (B−Y) _S , and Y _LS signals, imaging that requires immediacy such as an electronic still camera is performed. Suitable for white balance adjustment device. Also, once the color difference signal (RY, BY) is obtained,
Since the R, G, and B signals are calculated, it is easy to apply color clipping to the high-saturation object signal, thereby preventing the object object color from being adversely affected. If there is no need for the clip, the clip may be sent directly to the averaging unit in the R, G, B signal state before the color difference signal.

FIG. 7 is a block diagram of a third embodiment of the present invention.
Reference numerals 4 and 16 denote the same blocks as in the second embodiment, reference numeral 17 denotes a shutter for determining the exposure time, and reference numeral 18 denotes an aperture.

In this embodiment, to remove the photometry sensor used in the second embodiment, the shutter, summer and configured to measure the brightness and the flicker amount of the external light from the aperture and Y _L output instead. That is,
Is controlled by the microcomputer 13, the Y _L signal level brightness and a shutter speed and the aperture value when appropriate, also measuring the time variation of the Y _L outputted intermittently generate an output from the image pickup element 2 To detect the flicker amount. Based on the above information, the limited range of the control voltages R _C and B _C when using the macro lens is determined. In this embodiment, since the photometric sensor 15 can be omitted, the cost can be reduced.

FIG. 8 is a block diagram of a fourth embodiment of the present invention.
Is the same block as in the first embodiment, and 19 is a zoom lens for changing the focal length of the imaging optical system.

In the present embodiment, in particular, in an imaging apparatus such as an electronic still camera that does not need to constantly output an imaging signal, when the use of a macro lens (attachment) is detected, first, the focal length of the zoom lens is temporarily reduced as data measurement. The control voltages R _C and B _C are determined as the wide-lens state, and the photographing is performed after returning to an arbitrary focal length during the actual photographing. As a result, the area of the high chroma object color in the screen can be reduced as much as possible, and more suitable data of white balance adjustment can be obtained.

FIG. 9 is a timing chart of a main part of the fifth embodiment of the present invention, showing a switching period and an averaging period of the averaging unit corresponding to the averaging units 10 and 11 in FIG. This embodiment has the same configuration as that of FIG. 1 except for the portion related to averaging.

As can be seen from FIG. 9, in this embodiment, when the use (wearing) of the macro lens is detected, the averaging period is partially intermittent. In other words, during macro shooting, high chroma subjects often occupy a large area in the center of the screen,
As shown in FIG. 9, the center portion (in both the horizontal scanning period and the direct scanning period) is set as a discrete pulse, so that the influence of the pulse can be prevented and a good white balance image can be obtained.

That is, in the present example, when averaging, a partial area of the screen is weighted. As mentioned above,
Instead of using discrete pulses, the color difference signals may be weighted and averaged by multiplying them by an appropriate coefficient in the central area of the screen.

FIG. 10 is a block diagram of a sixth embodiment of the present invention.
Is the same block as in the second embodiment, and 20 is a Y _L PEAK detector (comparator unit) for detecting whether the Y _L signal is within a certain level range.
FIG. 11 shows the circuit.

Hereinafter, the operation of the present embodiment will be described, but 1 to 11, 14, 15, 1
6 shows the same operation as in the second embodiment. The Y _L PEAK detector 20 outputs a high level when the Y _L signal is E ₂ <Y _L <E _1, that is, a low level otherwise.

In this case, E _1, E ₂ is set to correspond for example 105% of Y _L level, the signal level of 90%.

That, Y _L level from 90 to 105% if Y _L PEAK detector output Y _L P is at a high level. Y of _L P level becomes high is considered to have for low saturation object because situations do not occur is high and the color saturation brightness. Therefore, the color difference signal R-Y when the Y _L P high, B-Y and A / D converter 12
And sends the signal to the microcomputer 13
White balance is performed using Y _L , R−Y, and B−Y. Signal Y _L ,
R-Y, B-Y control voltages from R _C, means for deriving B _C is the same as in the second embodiment.

Further, the microcomputer 13 combines the white balance adjustment method using the Y _L PEAK detector and the adjustment method using the averaging unit, and derives a control voltage so as to compensate for the disadvantages of both methods. For example, it is conceivable to preferentially use information of a method in which a signal with lower saturation is detected from both types of detected color difference signals. In addition, in this embodiment, when using the macro lens, by using the Y _L PEAK detection method preferentially, it is possible to minimize the influence of the deterioration of the white balance adjustment by the averaging method during macro shooting. .

In each of the embodiments described above, the use of the macro lens is detected, for example, by mounting the macro lens, and correction is made to the white balance adjustment unit. However, the present invention is not limited to this. The white balance adjustment means may be corrected by detecting the use of a macro area (macro mechanism) of a lens or a macro lens.

Needless to say, a lens referred to as a “microlens” used mainly for imaging is also included in the microlens referred to in the present invention.

〔The invention's effect〕

As described above, according to the present invention, suitable white balance adjustment can be performed regardless of whether a macro lens is used or a macro area of an imaging lens is used.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the first embodiment, FIG. 3 is a configuration diagram of an averaging unit, FIG. FIG. 5 is a diagram for explaining a limited range of white balance adjustment,
FIG. 6 is a block diagram of a second embodiment of the present invention, FIG. 7 is a block diagram of a third embodiment of the present invention, and FIG.
FIG. 9 is a block diagram of a main part of a fifth embodiment of the present invention, FIG. 10 is a block diagram of a sixth embodiment of the present invention, and FIG. 11 is a circuit diagram of a Y _L PEAK detector. FIG. 12 is a block diagram of a conventional example. DESCRIPTION OF SYMBOLS 1 ... Macro lens 2 ... Image sensor 5 ... R gain control part 6 ... B gain control part 10, 11 ... Averaging part 13 ... Microcomputer

Claims (2)

(57) [Claims] An image sensor, first white balance adjusting means for performing white balance adjustment based on a signal including a signal obtained by averaging the output of the image sensor, and the image sensor having a luminance signal level within a predetermined range. Second white balance adjustment means for performing white balance adjustment based on the output signal of the above, detection means for detecting execution of close-up photography, and when the detection means detects execution of close-up photography, the second
A selecting means for preferentially selecting the white balance adjusting means and performing white balance adjustment. 2. An image pickup device, a white balance adjustment unit for performing white balance adjustment using an output signal of the image pickup device, a detection unit for detecting execution of close-up photography, and the detection unit detecting execution of close-up photography. And a white balance adjusting unit that adjusts white balance based on an output signal of the image sensor whose luminance signal level is within a predetermined range.