JPS63266437A - Color image pickup device - Google Patents

Abstract

PURPOSE:To enhance the proper correction of white balance by detecting light emitting quantity by a flash light emitting device and computing a control voltage from white balance constant for flash and an output form a color measuring circuit based on the computed result of the rate of the flash in an image pickup signal to an ambient color. CONSTITUTION:The image of an object is dissolved into three primary colors by an image pickup element 4 so as to be converted into electrical signals and the red component and the blue component of them are amplified in amplifiers 5 and 6. A photometry circuit 8 measures the light quantity from the object. Meanwhile the light measuring circuit 9 dissolves the light from a light source into three primary colors to convert into the electrical signals and outputs exchange signal of the red, the blue and a green components. With this constitution, an arithmetic control circuit 11 computes the rate of the flash light to the ambient color based on the information from the flash light emitting device 10, the circuit 8 and the circuit 9. Then it computes the control voltage from the white balance (WB) constant for flash and the output from the circuit 9 based on the above-mentioned arithmetic result so as to control the amplifiers 5 and 6. Thus, the proper WB correction can be possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color imaging device having a flash light emitting device such as a strobe.

[Conventional technology]

An example of conventional white balance adjustment is shown in FIG. In FIG. 10, 9 is a colorimetric sensor that separates the light source light into each color component (here, the three primary colors of red, blue, and green) and converts it into an electrical signal. 12 is a control unit that derives a white balance control signal based on the signal obtained in 9; 4 separates the subject image into three primary colors and converts them into electrical signals. The image sensor 6 is a B amplifier that amplifies the blue component of the subject obtained from the image sensor. 5 is an R amplifier that similarly amplifies the red component.

Also, 7 is the red light and green light amplified by 5 and 6.

and a signal processing unit that derives a predetermined signal based on the green signal sent from the green signal. Furthermore, 10 is a flash light emitting circuit.

The operation of the conventional example will be described below with reference to FIG.

9 exchange signals KR, KG for the red, blue, and green components of the light source.
, KB are obtained, and from these KR, KG, and KB, the control unit 12 determines the ratio of red to green and the ratio of blue to green of the light source light.

On the other hand, the subject can be photographed by the image sensor, which is RlG, B.
converted into different types of signals.

As is well known, white balance is the process of removing the influence of the light source light from the reflected light of the subject so that white objects can be reproduced as white. , B can be multiplied by KG/KB to perform white balance adjustment. In other words, the control unit 12 controls the 6 B amplifiers and the 5 R amplifiers as described above.
I'll send out a signal. The detailed operation of the control section 12 will be explained using FIG. 11. The outputs KR, KG, and KB of the colorimetric sensor 1 are output from the logarithmic compression circuit 12 included in 12.
-1.12-2.12-3, making effective use of the dynamic range and facilitating subsequent processing.

12-1.12-2゜12-3 output fogKR,i!
In ogKG, logKB, II o gKR and I
I o gKG is a 12-4 differential, nogKB and l
ogKG is input to each of the 12-5 differentials, and as a differential output! ! o g (KG/KR), j!
Obtain o g (KG/KB).

Normally, the differential outputs are sent to R and B amplifiers 6 and 5 via switches 12-8 and 12-9, respectively, and the white balance is adjusted.

On the other hand, when shooting with indirect light, a charging completion signal is sent from the flash light emitting device 10, and the switch 12-8.12-9 contacts the flash constant side, and the flash constant logSR,
Ao and gSB are sent.

This made it possible to perform correct white balance adjustment during shooting.

[Problem to be solved by the invention] However, when taking pictures using flashlight, if the subject is illuminated only by the flashlight, there is no problem with this method, but if the surroundings are bright and the light irradiating the subject is If the flash light is mixed with ambient light, the white balance will be shifted if adjusted using the white balance constant for the flash light. In particular, when the amount of flash light is small (daytime synchronization, etc.), or when the ambient light is under a light source such as a fluorescent light whose color is significantly different from the flash light, the white balance adjustment will be significantly off.

[Means (and effects) for solving the problem] In the present invention, the amount of light emitted by the flash light emitting device is detected, taking dimming into consideration,
Calculating the ratio of the flash light and ambient light in the imaging signal,
Based on the calculation results, it is possible to calculate the control voltage from the flash WB constant and the colorimetric circuit output to perform appropriate WB correction.

〔Example〕

1 to 8 show a first embodiment of the present invention, FIG. 1 is a combined block diagram, FIGS. 2 and 3 are detailed diagrams explaining a part of the overall diagram in detail, and FIGS. 4 and 5 1 is a timing chart showing the operation of this embodiment. FIG. 6 is a flash waveform diagram for explaining this embodiment, and FIG. 7-8 is a flowchart for explaining the operation of this embodiment.

In FIG. 1, 1 is an optical system that focuses the subject image, 2a
2b is a driver that drives the diaphragm; 3a is a shutter that limits the incident time of the subject light; and 3b is a driver that drives the shutter.

Furthermore, blocks 4 to 7, 9, and 10 have the same functions as the blocks with the same numbers described in the conventional example. 8 is a photometric circuit for measuring the amount of light passing through the diaphragm, and 11 is a photometry circuit for measuring the amount of light passing through the aperture, and 11 is a photometry circuit for measuring the amount of light passing through the aperture, and 11 is a photometry circuit that uses the information of 8, 9.
This is an arithmetic control circuit that controls A.

FIG. 2 is a diagram explaining in detail 10 flashlight emitting devices, in which 10-1 is a light emitting part that emits flashlight, and 10-2 is a 10-
A charging capacitor that stores the charge necessary to make 1 emit light, 10-3 is 10-1.10 based on the control signal of 11.
10-4 is a light receiving section that receives the light of 10-5, and 10-5 is a flash light emitting section that pre-emits light for distance measurement.

Figure 3 is a block diagram explaining in detail the photometric circuit No. 8.
8-1 is a photometric sensor that performs photoelectric conversion, 8-2 is an integrator that integrates the output of the photometric sensor, 8-3 is a constant voltage reducer that outputs a constant value, and 8-4 is the integrator output of 8-2. A comparator 8-3 compares the magnitude of the constant voltage value, and 8-5 is a switch circuit that switches between the photometric sensor output of 8-1 and the comparator output of 8-4.

The operation of this embodiment will be described below with reference to FIGS. 1 to 8.

As shown in FIG. 7, when the power is turned on, n in the memory 11 is set to n=o (101), and the photometric circuit 8 and the colorimetric circuit 9 are started and started working (at this time, 8-5 The switch is connected to the photometric sensor side, and the exposure value Ev is obtained (102).

Next i: 10-5 (7) Emit light from the pre-emission section, 10-
The light is received by the blurred light receiving section No. 4, distance is measured based on the time difference, and the aperture value A' is set (103). After that, check whether there is a strobe charge signal from 10-2 (104), and if it is not full, perform normal general photography without using a flash (105).
, if it is complete, the guide number (GNo.
) value, aperture value (A'), and distance (D) are input to 11 and stored (106). Next, the aperture of 2a is stopped down to the given aperture value A' via 2b (107), and the shutter of 3a is opened for the determined seconds (ts□) < (108
). At the same time, the colorimetric output of 9 is held (109).

After holding, a flash is emitted at 10. The light emission start time is set to t=0, and at the same time, the switch 8-5 is connected to the comparator output.

Next, it is checked whether the output of 8 (comparator output of 8-4) is at low level (111). To explain the operation of this 8, the photometric sensor output of 8-1 is input to the integrator 8-2 and integrated, and the integrated output is sent to the comparator 8-4 at the constant voltage of 8-3, which is the appropriate photometric level. V2. ．． compared to At this time, the integrator is reset at the start of flash light emission and performs integration from t=O to t=tso. When the integral value S is larger than V t e l, the output of 8-4 is at a high level, and when it is smaller, it is at a low level (as mentioned above, the switch 8-5 is on the comparator side during the integration period, and on the photometric sensor side during the other periods. ). Further, the above operation is shown in Fig. 4.5.

(a) is a flash waveform of 10 and the flash start time is set to 1=0. Further, the flash duration is t II when the light is fully emitted. (
B) shows the state of shutter control, and the shutter opens at t=0 and closes at t=til.

(C) is the signal P sent from 11 to the integrator 8-2, which resets the integrator when 1=0, as described below.

is at a high level so as to be in an integral state while it is at a low level.

(D) is the output S of the integrator 8-2, which is reset when 1=0, and the photometric sensor output is integrated during the period when P is at a high level.

(E) outputs a switch of 8-5, and the integration period is 8-4.
is the comparator output, and S in (d) is V r e
If the level is lower than I, it is a low level, and if it is higher, it is a high level. Other than the integration period, it is the photometric sensor output.

Now, if 111 is at a low level, as can be seen from the above explanation, this means that the integral output S is smaller than Vl, so the amount of light will not exceed.

So next, let's check whether t < t s'r11
2), if t<tst, flash light is being emitted, so turn L again.
Check whether s is low level. When L3 is low level, t≧
If tst is reached, it is confirmed whether the WB control voltage has been derived by calculation (116). Specifically, as described below
Since n=1 is set upon completion of the B control voltage derivation, it is confirmed whether n=1 or not. If n=1, the flow is introduced, and if n=0, it is not derived. If it has been derived, check whether t≧tso in 119, and if it has not been derived, WB control voltage calculation in 117, 118
control voltage is output, and in step 119 it is confirmed that t≧tsn.

If t≧t□ in step 119, the shutter is closed and the image signal is read out, and if t<tsn, the process returns to step 111 again.

Next, when Ls is at a high level, the integral level S is V2
1. Therefore, if the flash light is being emitted, it must be immediately interrupted. Therefore, first check with 113 whether the flash light is being emitted.Specifically, check if P is at a high level. If the level is high, the light is being emitted, so the light emission is stopped (114), and at the same time, P is set to the low level.Furthermore, the flash light emission time t is stored (115).

Proceed to step 116 onwards. Further, in step 113, if P is at a low level, that is, the flash is not emitting, step 116 is performed. Below 1
16 and subsequent steps are as described above.

Two operation examples shown in FIGS. 4 and 5 will be explained using the above flow.

First, in FIG. 4, since the integral output S does not exceed the level Vl, it remains low level until the end, and at the time 1=t, the WB control voltage is calculated and output by 117 and 118, and 5, A++ and Aa of 6 are controlled and WB is adjusted.

Next, in FIG. 5, the integral output S is 1=1. At the time of V r
Since e exceeds I, at that point R becomes high level and flash emission stops due to 113 and 114, resulting in a stop time t,
is memorized. From then on 1=1. W by 117.118
The B control voltage is calculated and output, and WB adjustment is performed.

Next, the WB control voltage calculation in step 117 will be specifically explained using FIG.

First, in step 122, it is confirmed that t, ≧t□, and if yes, k is derived from (D is the subject distance, G, is the guide number of the light source) (123). Here, A is a value obtained by calculating (EV=exposure value obtained by photometry, 1/T=shutter synchronization speed).

This k represents the ratio between the amount of flash light and the amount of ambient light.

Next, WB control voltages C2 and C6 when not issuing a flash
To, l CIl= d−I! n −+ e a 1l CB = f−1nKa0g(d, e, f, g
: constant) (124, 125) In addition, k and flash light source correction control voltage (constant value)
Mixed light WB control voltage CR'v using C□+Cl18
Calculate C%' using the following formula (126°C8・=C・+k
C...k+1 C8=C・10kG...k+1 And as n=n+1 (n=0 to n=1), (12
8), the calculation of 117 is completed.

On the other hand 1. <1. In case A, since the flash is stopped midway, the amount of flash issued is smaller than when t≧tsy (full flash). In that case, the WB control voltage must be derived in consideration of the reduced amount of light emission.

First, the flash waveform is drawn as a straight line y=a as shown in Figure 6.
-t, y==l) a Approximate by the part surrounded by t+c and y=Q.

Then, the amount of flash light emission is derived using the area ratio.

First 1. <1. In the case of , the area y corresponding to the amount of light emission is at, ' y , = 2 (131) In addition, if tr≧t, the area yr' equivalent to the amount of light emission in the case of full light emission is yt
' = a · tp ' tst/2, so G in the case of full light emission. is changed as follows.

GNO=(y,/(a'tp' tst/2
))” GN.

Based on the C9° obtained here, the control voltage is derived by the following calculation (123).

[Other Examples]

FIG. 9 is a flowchart for explaining the second embodiment of the present invention.

In the first embodiment, the so-called auto mode was used in which distance information was obtained by the flash light emitting device 10 and the aperture was automatically set, but in the FN mode, the aperture is set by the photographer.

Similar WB adjustment can be performed in the set mode as well. In this case, the operations of flash flashing and distance measurement performed in step 103 are not necessary, and the aperture value set by the flash light emitting device is used as A' to narrow down the aperture, and this A' can also be used in calculations.

In addition, in the first embodiment, R, G are used as detection components of the colorimetric circuit.
, 83 colors are detected, but white balance adjustment may be performed by detecting R and 82 colors and predicting the G component.

Further, although RlG and B3 primary colors are used as outputs of the image sensor and the colorimeter circuit, complementary color signals may be used.

〔Effect of the invention〕

As explained above, by detecting the amount of flash light emitted when shooting using a flash light source and adjusting the WB according to the ratio with the ambient light, even when the amount of flash light emitted is small or the ambient light is fluorescent light, Appropriate WP adjustment is now possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIGS. 2 and 3 are block diagrams explaining a part of FIG. 1 in detail, and FIGS. 4 and 5 are block diagrams showing the first embodiment of the present invention. A timing chart explaining the operation of the embodiment; FIG. 6 is a flash waveform diagram; FIGS. 7 and 8 are flowcharts explaining the first embodiment; FIG. 9 is a flowchart explaining the second embodiment; 10 and 11 are block diagrams showing conventional examples, 1 is an optical system, 2a is an aperture, 2b is a driver for 2a, 3
a is a shutter, 3b is a driver for 3a, 4 is an image sensor, 5 is an R signal amplifier, 6 is a B signal amplifier, 7 is a signal processing unit that obtains a predetermined signal, 8 is a photometric circuit, and 9 is a colorimetric circuit , 10 is a flashlight emitting device, 11 is an arithmetic control circuit, 10-1 is a flashlight emitting unit, 10-2 is a charging capacitor, 1
0-3 is a light emission control circuit, 10-4 is a light receiving section that receives the flash light, 10-5 is a flash light emitting section, 8-1 is a photometric sensor, 8-2 is an integrator, and 8-3 is a constant voltage source. , 8-4 is a comparator, 8-5 is a switch 12 is a conventional control unit 12-1.12-2.12-3 is a logarithmic compression circuit 12-4
．． 12-5 is a differential gear 12-6. 12-7 is a strobe constant generation source 12-8.
12-9 is switch 3rd ward

Claims (1)

[Claims] An imaging device that converts subject light into an electrical signal and outputs a plurality of color signals, a light source color detection device that detects the color of the light source, a dimmable flash light emitting device, and when the flash light emitting device is dimmed, A flash light emission amount detection means having a dimming light amount detection section for detecting the light amount of the light control, and a control means for controlling the color balance of the color signal based on the detection output of the light emission amount detection means and the detection output of the light source detection means. A color imaging device with