JPH0549034A - Electronic picture device - Google Patents

Abstract

PURPOSE:To provide a proper red color component in the outdoor pickup in the morning and evening and to obtain a natural video image by correcting the adjustment of a signal strength of three optical primary colors subjected to white balance adjustment in response to the color temperature of the sunlight. CONSTITUTION:The color temperature of the sunlight changes with the altitude of the sun and on the other hand, the altitude of the sun depends on the longitude, latitude, the altitude and date and time at a point of a district. Data representing the relation between the altitude of the sun and the color temperature is given in advance to a color temperature decision section 4A, and the color temperature decision section 4A decides the color temperature based on each data received at image pickup. Moreover, a color temperature conversion section 4B corrects the adjustment value of each signal intensity of three primary colors of light obtained by usual white balance at a white balance adjustment section 3 depending on a value in response to the color temperature decided by the color temperature decision section 4A to decide the final white balance. The resulting color is taken as a white color for the image pickup thereby allowing natural reproduction of the light of the morning sun or the evening sun changing timewise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic image device such as an electronic still camera or a video camera.

[0002]

2. Description of the Related Art In this type of image device, in order to always obtain a correct color image irrespective of the secular change of the image pickup device, the signal intensities of the three primary colors of light must be balanced at the time of photographing. is necessary. Conventional color like this
As a means for adjusting the balance, the white light source is always recorded as white so that the light source at that time is white and the signal intensities of red (R), green (G), and blue (B) are uniform. A white balance adjusting means is used so that the white balance is normally adjusted automatically when the power is turned on.

[0003]

However, it is not ideal that the light source is always white in photographing in various situations. For example, in outdoor photography immediately after sunrise or immediately before sunset, if the color balance adjustment is performed with the setting of sunlight, that is, white, the image may be completely dull. That said, the sunlight on a sunny day, even in the morning and evening, is stronger than general artificial light sources, so
It is difficult to take white balance with light other than the sun when shooting outdoors.

Therefore, in the conventional electronic image device having the above-mentioned automatic white balance adjusting means, the white balance is once adjusted by sunlight, and then the
The method of artificially lowering (or raising) the color temperature by using a filter is used, but since the human eye adapts itself to the color temperature, how much should it be lowered (if raised)
It was difficult to properly judge whether it was good or to obtain the intended color tone.

An object of the present invention is to provide an automatic white balance adjusting means for making the light source white, and to adjust the color balance so as to obtain a natural image in the morning and evening when shooting outdoors in fine weather. An object is to provide an electronic image device that automatically adjusts.

[0006]

With reference to FIG. 1, which is one embodiment, the present invention is an adjustment for automatically adjusting the balance of the signal intensities of the three primary colors of light so that a white object is recorded as white during photographing. White balance adjusting means 3 for obtaining a value
And an image signal output unit 2 for processing and outputting the image signal output from the image pickup unit 1 based on the adjustment value. Then, the color temperature determining means 4A that determines the color temperature of the sunlight based on the altitude of the sun, and the adjustment values of the signal intensities of the three primary colors of light obtained by the white balance adjusting means 3 are used as the color temperature determining means. The above-described object is achieved by including the color temperature conversion unit 4B that corrects the color temperature of the sunlight determined in 4A to obtain a new adjustment value.

[0007]

[Function] The color temperature of sunlight changes according to the altitude of the sun. Fig. 4 shows an example of the relationship between the sun's altitude (the angular altitude from the horizon) and the color temperature of sunlight obtained from many observations. The lower the altitude, the lower the color temperature, that is, the stronger the redness. Is becoming This is because the lower the altitude, the stronger the influence of sunlight on the sunlight. Fig. 5 is a diagram in which the movement of the sun is projected on the celestial sphere, and the missing ellipse represents the ecliptic (path of the sun), but A is the region where the sun looks bright red, B is the region strongly affected by the atmosphere, C is a region where the influence of the atmosphere is not negligible, and D is a region where it is almost negligible. Although there are five curves a to e in FIG. 4,
This reflects the difference in transparency of the atmosphere,
It corresponds to very clear (a), clear (b), normal (c), cloudy (d), and extremely cloudy (e).

On the other hand, the altitude of the sun can be determined by the latitude, longitude, altitude and time (including date) of the point. Figure 6 shows how these factors affect the sun's altitude. The missing ellipse represents the ecliptic as in FIG. 5, but its inclination changes as the latitude changes, as indicated by arrow a. The change in longitude corresponds to arrow b, and the time of sunrise and sunset changes. A change in time (month / day) is indicated by an arrow c. The arrow d shows the change in altitude,
The higher the height, the faster the sunrise and the later the sunset.

Data indicating the relationship between the altitude of the sun and the color temperature of the sun as shown in FIG. 4 is given to the color temperature determining means 4A in advance, and data such as latitude, longitude, altitude and time are taken at the time of photographing. When the data is given, the color temperature determining means 4A determines the color temperature based on these data. Color temperature conversion means 4B
Is a value corresponding to the color temperature of the sunlight determined by the color temperature determining unit 4A, which is an adjustment value of each signal intensity of the three primary colors of light obtained by normally taking white balance by the white balance adjusting unit 3. To correct the final white balance. By shooting with that color as white, the ever-changing light of the rising sun or the setting sun is naturally reproduced. Incidentally, in the section of means and action for solving the above problems for explaining the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand, but the present invention is limited to the embodiments. Not something.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of an electronic image device. In addition to the camera imaging unit 1 that actually captures an image and the signal processing unit 2 that processes the captured signal to obtain an electrical image output, the apparatus of this embodiment has a white light source, and red (R) and green. (G), a white balance module 3 for performing a normal white balance adjustment that makes the signal intensities of the three primary colors of blue (B) light uniform, and a color that determines the color temperature based on the altitude of the sun. A temperature determination unit 4A and a color temperature conversion unit 4B that corrects the adjustment value of the signal intensity of each primary color obtained by the white balance module 3 according to the color temperature of the sunlight determined based on the altitude of the sun. It has and. Further, 5 is a clock, 6 is an altimeter that measures the altitude by utilizing the change in atmospheric pressure, and 7 is a data input section equipped with a keyboard or an image input device.

The color temperature determining unit 4A and the color temperature converting unit 4B are
It is composed of a CPU, various memories, and a microcomputer having an input / output interface. Astronomical data for associating the latitude, longitude, altitude and time with the altitude of the sun as described in FIG.
It is stored in the OM or the like. Since the data of the time from the clock 5 and the data of the altitude from the altimeter 6 are given to the color temperature determining section 4A respectively, the latitude and longitude of the location can be input by the key operation of the data input section 7. For example, the sun altitude at that time is required. In this way, the sun altitude is automatically determined from the data of latitude, longitude, altitude and time, not by direct observation, so there is no need to point the camera directly at the sun and there is no risk of damaging the image sensor. The timepiece 5 may be configured by using the internal timepiece of the microcomputer that constitutes the color temperature determination unit 4A. On the other hand, the relationship between the altitude of the sun and the color temperature of the sunlight was obtained by conducting detailed observations in advance and
Data in a non-volatile memory or the like. In this embodiment, as shown in FIG. 4, five levels of data corresponding to the transparency of the atmosphere are recorded. In this case, the transparency of the atmosphere is selected by the photographer according to the situation and set by the key operation of the data input unit 7.

Next, the white balance determining operation will be described with reference to FIG. This processing program is executed by the CPU when the power is turned on. In the figure, when the power is turned on, the CPU operates the white balance module 3 (step S1). As a result, an adjustment value for obtaining the signal intensity balance of the three primary colors R, G, B of light that gives a normal, neutral white as shown in FIG. 3A is obtained.

In this embodiment, the photographer can select whether or not to perform the color temperature conversion by operating the key of the data input section 7 as necessary. Therefore, the CPU next determines whether or not the color temperature conversion should be performed (step S2), and when it is necessary, the color temperature is determined based on the sun altitude using the various data as described above. (Step S3).
Then, the adjustment value of the signal intensity of each primary color obtained previously is corrected to a value according to this color temperature, the data is stored in a predetermined area of the RAM (step S4), and output to the signal processing unit (step). S5). That is, in this case, for example, FIG.
As shown in FIG. 5, conversion is performed so as to obtain a signal intensity balance of R, G, and B that gives reddish white appropriately according to the color temperature at that time, and an image is recorded with this color as “white”. It will be. Therefore, an image faithful to the color temperature of the subject can be obtained, and outdoor shooting can be performed that naturally reproduces the atmosphere of morning and evening.

When it is not set to perform color temperature conversion, it is determined in step S1 as shown in FIG.
R, G, which gives neutral white as shown in
The adjustment value data for obtaining the signal intensity balance of each of the B primary colors is stored as it is in a predetermined area of the RAM (step S4) and output to the signal processing unit (step S5).
As described above, the conventional system for determining the white balance is also provided and can be selected as needed, so that it is possible to flexibly cope with shooting in cloudy weather, nighttime, or indoor shooting under artificial lighting.

In the above-described embodiment, the latitude and longitude of the place are input by the key operation of the data input section 7, but the existing GPS (Global Position) is used.
A signal from the artificial satellite 11 may be used to automatically input from the position detection sensor 12, as is used in a Sensing type navigation system.

[0016]

According to the present invention, the adjustment values of the signal intensities of the three primary colors of light obtained by the white balance adjusting means are
Since the correction is made according to the color temperature of the sunlight, which is determined based on the altitude of the sun, when you take a white balance during outdoor shooting in the early morning or in the evening, an appropriate redness is automatically given to give a natural appearance. You can get the video you have.

[Brief description of drawings]

FIG. 1 is a block diagram of an electronic image device showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a white balance determination processing operation.

FIG. 3 is a diagram showing an example of a balance of RGB signal intensities obtained in a white balance module 3 and a color temperature conversion unit 4B.

FIG. 4 is a diagram showing an example of the relationship between the altitude of the sun and the color temperature of sunlight.

[Figure 5] A diagram of the movement of the sun projected on a celestial sphere

FIG. 6 is a diagram showing the influence of latitude, longitude, altitude and time on the sun altitude.

[Explanation of symbols]

 3 White balance module 4A Color temperature determination unit 4B Color temperature conversion unit

Claims (1)

[Claims] 1. A white balance adjusting means for obtaining an adjustment value for automatically adjusting the balance of signal intensities of the three primary colors of light so that a white object is recorded as white at the time of shooting, and a video signal output from the image pickup means. In an electronic image device comprising a video signal output means for processing and outputting based on an adjustment value, a color temperature determining means for determining a color temperature of sunlight based on the altitude of the sun, and a white balance adjusting means And a color temperature conversion unit that corrects the adjustment values of the signal intensities of the three primary colors of light according to the color temperature of the sunlight determined by the color temperature determination unit to obtain new adjustment values. A characteristic electronic image device.