JP3642127B2 - Video camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color video camera, and more particularly, to a color detection circuit that detects a specific color in an imaging signal.
[0002]
[Prior art]
A color video camera is provided with an image sensor such as a CCD having a function of generating an imaging signal reflecting video information of a subject. From the imaging signal generated by the image sensor, a signal such as a color difference signal reflecting the ratio of the three primary colors is generated for each pixel. Based on the signal such as the color difference signal, a predetermined format video signal such as the NTSC system is generated by predetermined means such as a color encoder. As a method for obtaining the above-described imaging signal, the imaging light is separated into three primary colors by optical means, and color signals for each of the three primary colors are obtained using three image sensors corresponding to the respective primary colors (three-plate type) and single A single image sensor is used, and a filter of the three primary colors or its complementary color is arranged on the imaging surface on the imaging surface, and an imaging signal generated by the single image sensor described above is obtained from the light from the subject that has passed through the filter (Single plate type) has been often used.
[0003]
In the three-plate type, a color signal for each of the three primary colors is directly output from the image sensor as an image pickup signal. However, in the case of a single-plate type, the image signal output from the single image sensor is output by a means such as a color separation circuit. A circuit configuration for generating a color signal for each primary color is required. The present invention can be applied to any of a three-plate type, a single-plate type, and a two-plate type.
[0004]
In a signal processing system of a conventional color video camera, a white balance adjustment unit is provided. The white balance adjustment unit is provided with three variable gain amplifiers corresponding to the color signals R (red), G (green), and B (blue), respectively. The gains of these three variable gain amplifiers are set so that the level of the color signals R, G, and B generated based on the image pickup signal with the color corresponding to is 1: 1: 1.
[0005]
As the above-described white balance control, that is, the gain setting method of the amplifier of the white balance adjustment unit, there are a feedback method and a feed forward method. In the feedback method, first, an appropriate gain initial value is set for the amplifier of the white balance adjustment unit. Then, the image signal obtained by imaging the color corresponding to white under the light source illuminating the subject is subjected to white balance adjustment using the above-described initial gain value and subsequent processing to obtain a color difference signal. And so on.
[0006]
A color detection pulse is generated in association with the color difference signal and the like, and white balance control is performed by performing data detection for white balance control with reference to the color detection pulse. As a specific method for generating a color detection pulse in relation to the color difference signal, a reference signal from the outside of the signal processing system, for example, video, based on the color difference signals RY and BY after white balance adjustment described above. A method for generating a color detection pulse by referring to a reference signal recorded in advance in a ROM or the like built in the camera is used.
[0007]
On the other hand, in the feedforward method, white balance control is performed in relation to the color signals R, G, and B before white balance adjustment. As a specific method, for example, the color signals R, G, and B before white balance adjustment are integrated by one field to obtain detection values, the ratio of these detection values is calculated, and the white balance is calculated based on this ratio. A method for performing control is used.
[0008]
When the white balance control as described above is correctly performed, the level ratio of the color signals R, G, and B output from the white balance adjustment unit correctly reflects the color of the subject.
[0009]
[Problems to be solved by the invention]
In order to perform white balance control satisfactorily, among the color signals R, G, and B generated based on the above-described imaging signals, data close to the color corresponding to white under the light source that illuminates the subject is white balance. It is desirable to be used for control. For this reason, in the feedback system, the color difference signals RY and BY generated after the white balance adjustment unit illuminate a subject such as the origin of the RY and BY planes. Only when the color corresponding to white under the light source is within a predetermined range from the point where the color is located, data close to the color corresponding to white under the light source that illuminates the subject is detected by means of generating a color detection pulse. Target methods have been used in the past. However, such a method is applicable only to the white balance control using the feedback method, and cannot be applied to the feed forward method.
[0010]
In the conventional video camera apparatus described above, a desired frame can be obtained from the color difference signals RY and BY generated by the white balance adjustment unit and the subsequent signal processing means by using a sampling frame set by a predetermined method. The color is extracted. For this reason, the setting position of the extraction frame must be changed depending on the desired color, and it is difficult to control such an extraction frame. Further, if the white balance adjustment performed before the color extracting operation is shifted for some reason, there is a possibility that a desired color cannot be extracted.
[0011]
Therefore, an object of the present invention is to perform good white balance control for both the feedback method and the feed forward method, and to control the setting position of the extraction frame according to a desired color. It is an object of the present invention to provide a video camera that is easy and can always extract a desired color without being affected by white balance adjustment.
[0012]
[Means for Solving the Problems]
  According to a first aspect of the present invention, there is provided a gain variable means for performing gain adjustment different from the gain for white balance adjustment on the supplied color signal,
  Only when the output obtained by performing a predetermined calculation on the output of the gain variable means is within a predetermined range,A signal indicating that the color signal is within a predetermined range from the position corresponding to white on the color planeA means to generateFirst and secondHaving color detection means;
  FirstSupply color signals before or after white balance adjustment to the color detection means; andFirstBy controlling the gain variable means included in the color detection means in relation to the color corresponding to white under the light source that illuminates the subject,FirstGenerate color detection meanssignalThe data detection means for detecting the color signal before white balance adjustment or after white balance adjustment as the detection target of data detection for white balance,
  Means for controlling the gain for white balance adjustment with reference to the output of the data detection means.And
  SecondSupply the color signal before white balance adjustment to the color detection means, andSecondBy controlling the gain variable means included in the color detection means in relation to the desired color,SecondGenerate color detection meanssignalByControl to output a color difference signal etc. only when the color difference signal etc. generated based on the supplied color signal is within a predetermined rangeIt is a video camera characterized by having a selection means.
[0014]
By using the means as described above, white balance control is performed in relation to the output of the gain variable means that performs gain control different from the gain for white balance adjustment provided in the color detection means. The white balance control can be performed by the feed forward method by supplying the color signal before white balance adjustment to the color detecting means. Also, white balance control can be performed in a feedback manner by supplying a color signal after white balance adjustment to the color detection means.
[0015]
Further, in the color detection means, the condition for generating the color detection pulse is set in relation to the color corresponding to white under the light source in which the supplied color signals R, G, B illuminate the subject, Since only the color signals R, G, and B within a predetermined range from the color corresponding to white under the light source that illuminates the subject can be selectively used for white balance control, good white balance control can be performed. .
[0016]
In addition, the above-described color difference signal is selectively supplied to the subsequent stage as an output color signal by referring to the pulse generated by the color detection means based on the color signal before white balance adjustment, so that it is not related to the desired color. The extraction frame can be fixed. Therefore, the difficulty in controlling the extraction frame corresponding to the desired color, which has been considered as a conventional problem, is solved, and the desired color can always be extracted without being affected by the white balance adjustment. It becomes possible.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIG. A CCD (not shown) generates an imaging signal and supplies it to an A / D converter, and an output of the A / D converter is supplied to a color separation circuit (not shown). The color separation circuit generates a luminance signal Y and color synthesis signals Cr and Cb based on the supplied A / D-converted imaging signal, and R, G, and B matrix units via the input terminals 1Y, 2r, and 2b. 4 is supplied. The luminance signal Y is further supplied to a luminance signal processing circuit (not shown).
[0018]
The R, G, B matrix unit 4 generates color signals R, G, B based on the supplied luminance signal Y and color composite signals Cr, Cb. The color signals R, G, and B are supplied to the white balance adjustment unit 5, the white balance control color detection circuit 12, the white balance control data detection circuit 13, and the output color signal control color detection circuit. On the other hand, the luminance signal processing circuit performs predetermined processing on the supplied luminance signal Y to generate a corrected luminance signal Y by removing noise, distortion, etc., as described later, to a color encoder (not shown). Supply.
[0019]
As described above, the white balance adjustment unit 5 includes three gain variable amplifiers corresponding to the color signals R, G, and B. In one embodiment of the present invention, the gains of the three variable gain amplifiers of the white balance adjusting unit 5 are controlled by a signal T for controlling the gain. The signal T for controlling the gain is generated by a microcomputer (hereinafter abbreviated as “microcomputer”) 7 that comprehensively controls the white balance adjustment and the output color signal, as will be described later. By controlling the white balance adjusting unit 5 in this way, the output of the white balance adjusting unit 5 becomes color signals R, G, and B having a level ratio that correctly reflects the color of the subject. The output of the white balance adjustment unit 5 is supplied to the gamma correction circuit 8.
[0020]
Gamma correction is performed by the gamma correction circuit 8 on the color signals R, G, and B output from the white balance adjustment unit. In the gamma correction, the color signal R output from the white balance adjustment unit is set so that the photoelectric conversion characteristic of the entire system including the image sensor and the video reproduction unit is set to 1 in order to correctly express the color gradation of the subject. This is performed by applying a predetermined gain to each of G and B. The output of the gamma correction circuit 8 is supplied to the RY and BY matrix unit 9.
[0021]
The RY and BY matrix unit 9 generates color difference signals RY and BY based on the supplied gamma-corrected color signals R, G, and B, and supplies them to the output color signal transmission unit 15. To do. The output color signal transmission unit 15 refers to the color detection pulse p2 generated by the output color signal control color detection circuit 14 as will be described later, and outputs the color difference signals RY and BY via terminals 16 and 17. This is selectively supplied to a color encoder (not shown). In general, there are two pulse generation methods, one that is performed by maintaining a high level for a predetermined time (used in a positive logic digital circuit) and one that is performed by maintaining a low level for a predetermined time (digital of negative logic). Used in the circuit). Any of these can be used as the pulses used in the present invention, that is, the above-described color detection pulse p2, the color detection pulse p1 and the color detection pulse p described later.
[0022]
The color encoder is a predetermined unit (not shown) based on the color difference signals RY and BY supplied selectively from the output color signal transmission unit 15 and the luminance signal supplied from the luminance signal processing circuit. A video signal in a predetermined format, such as the NTSC system, is generated with reference to the synchronization signal, subcarrier, etc. supplied from.
[0023]
An operation for setting the gains of the three gain variable amplifiers of the white balance control, that is, the white balance adjustment unit 5, will be described in detail. In this embodiment, white balance control is performed by a feed forward method. As described above, the color signals R, G, B before white balance adjustment are supplied from the R, G, B matrix unit 4 to the white balance control color detection circuit 12 and the white balance control data detection circuit 13. The white balance control color detection circuit 12 is further supplied with a signal S1 for gain control related to a color corresponding to white under a light source that illuminates the subject from the microcomputer 7.
[0024]
The white balance control color detection circuit 12 performs gain control in relation to the supplied color signals R, G, B before white balance adjustment and the color corresponding to white under the light source illuminating the subject. Based on S1, a color detection pulse p1 is generated as described later. The color detection pulse p1 is supplied to the data detection circuit 13 for white balance control.
[0025]
The data detection circuit 13 for white balance control performs data detection for white balance control with reference to the color detection pulse p1. That is, for example, the color signals R, G, and B when the color detection pulse p1 is generated are set as detection targets for white balance data detection. The output of the white balance control data detection circuit 13 is supplied to the microcomputer 7. The microcomputer 7 generates a signal T for controlling the gain of the amplifier of the white balance adjustment unit 5 based on the supplied data after detection, and supplies the signal T to the white balance adjustment unit 5.
[0026]
The configuration and operation of the white balance control color detection circuit 12 will be described in detail with reference to FIG. The white balance control color detection circuit 12 is configured to output a difference signal R− based on the outputs of the variable gain amplifier group 30 and the variable gain amplifier group 30 including three variable gain amplifiers corresponding to the supplied color signals R, G, and B. A difference signal generation circuit 31 that generates G and B-G, and a pulse generation circuit 32 that generates a color detection pulse p1 based on the difference signal generated by the difference signal generation circuit 31 as will be described later. .
[0027]
The gain of the variable gain amplifier group 30 performs gain control in relation to a color corresponding to white under the light source illuminating the subject, which is supplied from the microcomputer 7 to the color detection circuit 12 for white balance control. Controlled by signal S1. That is, when the color signals R, G, and B supplied to the variable gain amplifier group 30 are colors corresponding to white under the light source illuminating the subject, the output of the variable gain amplifier group 30 is a predetermined ratio, for example. The gain of the variable gain amplifier group 30 is controlled so that R: G: B = 1: 1: 1.
[0028]
Based on the output of the variable gain amplifier group 30 of the color detection circuit 12 for white balance control, the difference signal generation circuit 31 generates difference signals RG and BG. In this embodiment, the difference signals RG and BG are used as the determination signals. When the gain setting as described above, that is, when the color signals R, G, and B supplied to the variable gain amplifier group 30 are colors corresponding to white under the light source illuminating the subject, R: G: B = 1: 1: 1 When the gain setting is made, the difference signal is RG = 0 and BG = 0, and is located at the origin of the RG and RB planes. become.
[0029]
Under actual use conditions, it is often possible to obtain only a color that deviates to some extent from the color corresponding to white under the light source that illuminates the subject. For this reason, a predetermined range is set in advance from the point where a color corresponding to white under the light source illuminating the subject, such as the origin of the RG and RB planes, is located. Then, based on the difference signals RG and RB generated by the difference signal generation circuit 31, the color detection pulse p1 is generated with reference to the predetermined range described above. The predetermined range referred to for the generation of the color detection pulse p1 is set in consideration of the use conditions of the video camera when white balance control is performed.
[0030]
As a specific method of generating the color detection pulse p1 with reference to the predetermined range, only when the difference signals RG and RB are determined to be inside the predetermined range, for example, only. In addition, a method can be used in which the pulse generation circuit 32 generates the color detection pulse p1, for example, by maintaining the high level for a predetermined time. This color detection pulse p1 is supplied to the data detection circuit 13 for white balance control.
[0031]
Next, control of the output color signal, that is, an operation for selectively supplying the color difference signals RY and BY as output color signals to the subsequent stage will be described in detail. As described above, the color signals R, G, B before white balance adjustment are supplied from the R, G, B matrix unit 4 to the output color signal control color detection circuit 14. The output color signal control color detection circuit 14 is further supplied from the microcomputer 7 with a signal S2 for performing control related to a desired color. On the other hand, the color difference signals RY and BY supplied from the RY and BY matrix 9 are supplied to the output color signal transmission unit 15.
[0032]
Based on the supplied color signals R, G, B before white balance adjustment and a signal S2 that performs control related to a desired color, the output color signal control color detection circuit 14 performs color detection pulses as described later. Generate p2. The color detection pulse p <b> 2 is supplied to the output color signal transmission unit 15.
[0033]
The output color signal transmission unit 15 includes two switches respectively corresponding to the color difference signals RY and BY. These switches selectively supply the color difference signals RY and BY supplied from the RY and BY matrix 9 described above with reference to the color detection pulse p2 as output color signals. That is, for example, when the color detection pulse p <b> 2 is generated, the color difference signals RY and BY are supplied to the above-described color encoder via the terminals 16 and 17. By such an operation of the output color signal transmission unit 15, it is possible to selectively extract the color difference signals RY and BY corresponding to colors within a predetermined range from a desired color.
[0034]
The configuration and operation of the output color signal control color detection circuit 14 will be described in detail. The output color signal control color detection circuit 14 is configured in the same manner as the white balance control color detection circuit 12. That is, a gain variable amplifier group including three gain variable amplifiers corresponding to the supplied color signals R, G, and B before white balance adjustment, and the difference signals RG and B− based on the outputs of the gain variable amplifier groups. A difference signal generation circuit for generating G and a pulse generation circuit for generating a color detection pulse p2 based on the difference signal generated by the difference signal generation circuit as will be described later.
[0035]
The gain of the variable gain amplifier group of the output color signal control color detection circuit 14 is controlled by a signal S2 that controls the desired color supplied from the microcomputer 7 to the output color signal control color detection circuit 14. Is done. For example, the inverse ratio of the color signals R, G, and B corresponding to the desired color is set as the gain of the variable gain amplifier group 30 by the signal S2 that performs control related to the desired color. When such gain setting is performed, when the color signals R, G, and B before white balance adjustment supplied to the variable amplifier group have a desired color, the output of the gain variable amplifier group 30 is R: G. : B = 1: 1: 1.
[0036]
Based on the output of the above-described variable gain amplifier group, the difference signal generation circuit generates difference signals RG and BG. In this embodiment, similarly to the above-described white balance control color detection circuit 12, the output color signal control color detection circuit 14 uses the difference signals RG and BG as the determination signals. ing.
[0037]
When the gain of the variable gain amplifier group is set as the inverse ratio of the color signals R, G, and B corresponding to the desired color as described above, the color before white balance adjustment supplied to the variable gain amplifier group When the signals R, G, and B are in the desired colors, the output of the variable gain amplifier group is R: G: B = 1: 1: 1, so that the difference signals are RG = 0, BG = 0, and is located at the origin of the RG and RB planes.
[0038]
In actual use conditions, it is often possible to obtain only a color that deviates from a desired color to some extent. For this reason, a predetermined range is preset from the point where a desired color such as the origin of the RG and RB planes is located. Then, based on the difference signals RG and RB generated by the difference signal generation circuit in the output color signal control color detection circuit 14, the color detection pulse p2 is generated with reference to the predetermined range described above. Made. The predetermined range that is referred to for the generation of the color detection pulse p2 is set in consideration of the use conditions of the video camera at the time of imaging.
[0039]
As a specific method for generating the color detection pulse p2 with reference to the above-mentioned predetermined range, it is determined that the above-described difference signals RG and RB are, for example, inside the predetermined range as described above. Only when the pulse generation circuit maintains the high level for a predetermined time, for example, a method of generating the color detection pulse p2 can be used. The color detection pulse p2 is supplied to the output color signal transmission unit 15.
[0040]
In the embodiment of the present invention described above, the output of the gain variable means for applying a gain different from the gain for white balance adjustment to the color signals R, G, B as the determination signal generated in the color detection circuit. Difference signals RG and BG are used. On the other hand, as shown in FIG. 3, it is possible to use the output ratio signals R / G and B / G of the above-described gain variable means as the determination signal generated in the color detection circuit.
[0041]
In FIG. 3, the gain variable amplifier group 40 is the same as the gain variable amplifier group 30 in the above-described white balance control color detection circuit 12 shown in FIG. The gain variable amplifier group 40 is supplied with a signal S for controlling the gain in relation to the color desired to be detected from a predetermined means. The color to be detected is determined by the usage method of the color detection circuit shown in FIG. That is, when the color detection circuit shown in FIG. 3 is used as a color detection circuit for white balance control, the color corresponds to white under the light source that illuminates the subject. Further, when the color detection circuit shown in FIG. 3 is used as an output color signal control color detection circuit, a desired color is obtained. The output of the variable gain amplifier group 40 is supplied to a ratio signal generation circuit 41 that generates ratio signals R / G and B / G.
[0042]
The gain control of the variable gain amplifier group 40 performed by the signal S for controlling the gain related to the color to be detected will be described below. When the supplied color signals R, G, and B are colors to be detected, the gain variable amplifier group is set so that the output of the gain variable amplifier group 40 becomes a predetermined ratio, for example, R: G: B = 1: 1: 1. A gain of 40 is controlled. When such gain control is performed, R / G = 1 and B / G = 1. This is located at a point (1.0, 1.0) on the R / G and B / G planes.
[0043]
Use of the video camera from the point where the color to be detected such as the point (1.0, 1.0) on the plane of the ratio signal R / G, B / G generated by the ratio signal generation circuit 41 is R / G, B / G The pulse generation means 42 generates the color detection pulse p, for example, by maintaining the high level for a predetermined time only when it is within, for example, a predetermined range in consideration of the conditions.
[0044]
In the above-described color detection circuit using the difference signal as the determination signal, the gain variable means for applying a gain different from the gain for white balance adjustment to the color signals R, G, and B (in the above-described embodiment, As the output of the variable gain amplifier group 30) becomes smaller, there arises a problem that the color misregistration as the ratio of R, G, and B increases even if the difference signal is within a preset range. However, such a problem does not occur when a ratio signal is used as the determination signal as in the configuration shown in FIG. However, since the circuit that performs the division necessary to generate the ratio signal is larger in scale than the circuit that performs the subtraction necessary to generate the difference signal, the difference signal and the ratio signal are used as determination signals. Which of these is used may be determined in consideration of performance required for the video camera, purpose of use, and the like.
[0045]
In the embodiment of the present invention, as described above, the white balance control is performed by the feed forward method. On the other hand, the color signal after white balance adjustment, that is, the output of the white balance adjustment unit 5 is supplied to the color detection circuit 12 and the white balance data detection circuit 13, and the other configurations are the same as in this embodiment. Thus, it is possible to perform white balance control by a feedback method.
[0046]
【The invention's effect】
As described above, the present invention is a gain for applying a gain related to a color corresponding to white under a light source illuminating a subject to the color signals R, G, and B before white balance adjustment or after white balance adjustment. Only when the output of the gain variable means satisfies a predetermined condition using the variable means, the color signals R, G, B before the white balance adjustment are detected by the data detection for white balance control. It is what.
[0047]
Therefore, when the above-mentioned predetermined condition is appropriately set in relation to the color corresponding to white under the light source illuminating the subject, the feedforward method or the feedback method can be controlled. Thus, data close to white can be set as a detection target of data detection for white balance control, and favorable white balance adjustment can be performed.
[0048]
Further, according to the present invention, a color signal R, G, B before white balance adjustment is multiplied by a gain related to a desired color separately from a gain related to white balance adjustment, and an output obtained by the gain is preset. Only when the predetermined condition is satisfied, the color difference signal generated by the white balance adjustment unit and the subsequent signal processing based on the color signals R, G, and B before the white balance adjustment is selectively transferred to the subsequent image. The signal is supplied to the signal generating means.
[0049]
Accordingly, it is possible to extract a desired color by appropriately setting the above-described predetermined condition in relation to the desired color. For this reason, it is not necessary to change the setting position of the extraction frame depending on the desired color, and the setting position of the extraction frame can be fixed, so that the setting position of the extraction frame can be easily controlled. In addition, it is possible to extract a desired color without being affected by white balance adjustment.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a video camera to which the present invention is applied.
FIG. 2 is a block diagram showing a configuration of an example of a color detection circuit according to an embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of another example of the color detection circuit in one embodiment of the present invention.
[Explanation of symbols]
4 ... R, G, B matrix part, 5 ... White balance adjustment part, 12 ... White balance control color detection circuit, 13 ... White balance control data detection circuit, 14 ... Output Color signal control color detection circuit, 15 ... output color signal transmission unit, 30 ... gain variable amplifier group, 31 ... difference signal generation circuit, 32 ... pulse generation circuit, 41 ... ratio signal Generator circuit

Claims (7)

Gain variable means for performing gain adjustment different from the gain for white balance adjustment on the supplied color signal;
A signal indicating that the color signal is within the predetermined range from the position corresponding to white on the color plane only when the output obtained by performing the predetermined calculation is within the predetermined range as the output of the gain varying means. First and second color detection means comprising means for generating,
White above first color detecting means supplies the color signals of the white balance adjustment before or after the white balance adjustment, and the gain varying means contained in the first color detection means, under a light source illuminating the object By referring to the signal generated by the first color detection means, the color signal before white balance adjustment or after white balance adjustment is used for data detection for white balance. Data detection means to be detected by
Referring to the output of the data detecting means have a means for controlling the gain for white balance adjustment,
It said supplying a color signal before white balance adjustment in a second color detection means, and said gain varying means contained in the second color detection means, by controlling connection with the desired color, the first Control is performed so that the color difference signal or the like is output only when the color difference signal or the like generated based on the supplied color signal is within the predetermined range by the signal generated by the second color detection means. A video camera comprising selection means. In claim 1 ,
A video camera characterized in that the gain control signal of the gain varying means in the first and second color detecting means is generated by a microcomputer that comprehensively controls white balance and output color signals. In claim 1 ,
Only when the output obtained by performing the predetermined calculation on the output of the gain varying means in the first and second color detecting means is within a predetermined range , the color signal is white on the color plane. Means for generating a signal indicating that the signal is within a predetermined range from the corresponding position ,
Means for generating a predetermined determination signal by performing the predetermined calculation on the output of the gain variable means;
A video camera comprising means for generating the signal only when the determination signal is within a preset range. In claim 3 ,
The means for generating the determination signal is:
A video camera comprising means for generating a difference signal based on an output of the gain varying means. In claim 3 ,
The means for generating the determination signal is:
A video camera comprising means for generating a ratio signal based on the output of the gain varying means. In claim 1,
Means for controlling the gain for white balance adjustment with reference to the output of the data detection means,
A video camera characterized by a microcomputer that comprehensively controls white balance and output color signals. In claim 1 ,
The selection means is:
A video camera comprising a switch controlled by referring to a signal indicating that a color signal is within a predetermined range from a position corresponding to white in the color plane generated by the second color detecting means. .

Images