JP2010041507A - View finder display circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a view finder display circuit for detecting an object by a color difference signal. <P>SOLUTION: The view finder display circuit includes: a conversion means (10) for generating a luminance signal and two sorts of color difference signals from a video signal; a reference value generation means (12) for performing color determination based on signal levels of the color difference signals in a predetermined color detection area in a display picture displayed by the video signal and generating a reference value of the color-determined signal levels; a color comparison means (11) for comparing the color difference signals with the reference value and determining coincidence when each compared result is within a predetermined deviation; a superimposed video signal generation means (15) for generating a predetermined superimposed video signal; and a mixing means (16) for mixing the luminance signal corresponding to the color difference signal determined as coincidence with the superimposed video signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display circuit for a viewfinder that can identify colors even in a monochrome viewfinder used for a television camera.

  Broadcast television cameras often use a black and white viewfinder. This is because the black-and-white video is easier for the cameraman who is required to always focus on the subject because the gradation is easier to understand and the contour portion is clearer, making it easier to focus.

  However, it may be easier for the photographer to take the angle of view when the color is known. For example, let's say that a field with many flowers blooms with a different color. If a photographer wants to zoom in on a flower of a different color while shooting in the field, the flowers will all look the same in the black and white viewfinder. Especially when countless flowers are mixed in the frame, it is very difficult to find them.

  Another example is when a team of blue and red uniforms is playing a match in a soccer game. The photographer takes into consideration the ball and the number of players from both teams in the angle of view. However, with a black and white viewfinder, it will be difficult because all players will look the same. If a flower is a subject, it is possible to find a single flower with a different color if time is taken, but not in a fast-paced soccer game. If you want to see the color, you can change from a black and white viewfinder to a color viewfinder, but it has the drawback that focusing is difficult.

As a technique for detecting a specific color from a video signal and displaying it on a color monitor receiver or vector scope, a specific color is detected from the RGB video signal and only the color area detected by the color receiver is displayed in black and white. Thus, a technique for making the color detection region easy to understand is known (for example, see Patent Document 1).
JP-A-7-143510

  The conventional technique disclosed in Patent Document 1 described above displays the color detection area in black and white when displayed on a color receiver, and displays the color detection area in an oblique stripe pattern when displayed on a black and white viewfinder. Although displaying with (zebra pattern) is disclosed, any of them detects a specific color such as a skin color.

  However, since the scene changes when shooting with a television camera, which color is detected may vary from scene to scene. When detecting with a fixed color, it is necessary to change the setting of the detected color each time, which is troublesome. In addition, since detection is performed using the three primary colors of RGB, it is necessary to perform three types of settings for the color to be detected.

  In view of the above-described problems, an object of the present invention is to enable a cameraman to freely change the color detected by a television camera using a black and white viewfinder, and to detect an object using two types of color difference signals. It is an object of the present invention to provide a viewfinder display circuit capable of achieving the above.

  A viewfinder display circuit according to a first aspect of the present invention includes a conversion unit that generates a luminance signal and two kinds of color difference signals from a video signal obtained by processing an imaging signal, and a display screen displayed by the video signal. In a predetermined color detection area, color determination is performed based on the signal level of the color difference signal, and a reference value generation unit that generates a reference value of the signal level subjected to color determination; the color difference signal and the reference value; In comparison, the color comparison means for determining that the signals match if they are within a predetermined deviation, the superimposed image generation means for generating a predetermined predetermined superimposed image signal, and the color difference signal determined to be matched by the color comparison means Mixing means for mixing a luminance signal corresponding to the above and a superimposed video signal of the superimposed video generation means.

  The viewfinder display circuit according to a second aspect of the present invention is the viewfinder display circuit according to the first aspect of the present invention, wherein the superimposed image generation means generates a zebra pattern as a superimposed image signal; The color comparing means controls the output of the generating means when it is judged that the color comparing means agrees.

  The viewfinder display circuit according to a third aspect of the present invention is the viewfinder display circuit according to the first aspect, wherein the reference value is a plurality of times of a signal level of the color difference signal included in the color detection area. It is determined by sampling.

  According to a fourth aspect of the viewfinder display circuit of the present invention, in the viewfinder display circuit of the first aspect, the color detection area is defined as a settable region located at the center of the display screen. It is characterized by that.

  According to the first aspect of the present invention, since the color determination reference value based on the signal level in the predetermined area is created, the photographer can specify the predetermined area, whereby the color can be specified flexibly, and the scene is displayed. Since there is no need to set a specific color each time the image is changed, the cameraman has an advantageous effect. In addition, by performing color comparison using two color difference signals, the configuration is more compact than a configuration using three primary colors.

  According to the second aspect of the present invention, superimposing the zebra pattern on the video signal has an effect of clarifying the color difference on the viewfinder.

  According to the third aspect of the present invention, the most frequently used color is the reference value, in other words, the color difference signal included in the predetermined area has almost the same level. By statistically processing, the variation of the reference value is reduced, and obtaining a stable reference value reduces the fluctuation due to the variation of the reference value, so that it has an effect that stable color can be detected.

  According to the fourth aspect of the present invention, it is possible to set an appropriate color detection area for the detection target by setting the predetermined area as the center of the screen, and it is possible to set a favorite color It has the effect which becomes.

  A viewfinder display circuit according to an embodiment of the present invention will be described with reference to FIGS.

[Circuit configuration]
FIG. 1 is a block diagram of a viewfinder display circuit of the present invention. The viewfinder display circuit according to the present embodiment includes a matrix circuit 10, a color comparison circuit 11, a color detection circuit 12, a color detection frame generation circuit 13, a frame on / off switch 14, and a superimposed video signal generation circuit 15. Instrument 16.

  The matrix circuit 10 generates a Y signal from the RGB signal obtained by the camera signal processing circuit (not shown) of the television camera on the one hand based on the equation (1) and sends it to the mixer 16. Then, the Y signal is subtracted from the R signal and the B signal, respectively, and converted into a Pr (R−Y) signal and a Pb (B−Y) signal, which are sent to the color comparison circuit 11 and the color detection circuit 12.

    Y = 0.299R + 0.587G + 0.114B (1)

  The color comparison circuit 11 compares the input Pr signal and Pb signal with the set value from the color detection circuit 12 and detects whether or not they match. If the comparison results match, the superimposed video signal generation circuit 15 is controlled to generate a superimposed video signal. When the comparison results do not match, a control signal indicating that the superimposed video signal is not generated is output to the superimposed video signal generation circuit 15. Here, the determination as to whether or not they coincide with each other is based on whether or not they are within a certain deviation from the set value.

  The color detection circuit 12 sets and outputs the value of the signal level having the largest number of Pr signals and Pb signals within the color detection frame (also referred to as “color detection area”) from the color detection frame generation circuit 13. . This set value is color-determined from the reference values for the two Pr signals and Pb signals. For example, if there are many red elements in a color detection area that can be arbitrarily sized, the Pr signal level increases, and if there are many blue elements, the Pb signal level increases. This will be described in detail later. Note that the color detection area is preferably defined as a settable area located at the center of the display screen. As described above, the color detection circuit 12 performs color determination based on the signal levels of the two types of color difference signals in the predetermined color detection area in the display screen displayed by the video signal, and the color-determined signal level. Generate a reference value for.

  The color detection frame generation circuit 13 generates a color detection frame (that is, a “color detection area”) according to an area signal outside the circuit. The area information input to the color detection frame generation circuit 13 is set on a television camera setting screen (not shown) as a color detection area of an arbitrary size defined as the center of the display screen. Alternatively, a plurality of area groups may be displayed and selected. Furthermore, the color detection area may be defined in units of time, or the color detection area may be defined by the coordinate value of the horizontal axis-vertical axis (XY axis) of the display screen in units of the number of pixels. In any case, the color detection area is set so as to be within the detection target (object) on the display screen of the television camera.

  The frame on / off switch 14 is a switch that the user turns on / off according to the necessity of the color detection frame. This is turned off when the setting of the color detection frame (that is, “color detection area”) is completed and the setting is not necessary, and is turned on when the setting of the color detection frame is necessary. This on / off control is controlled by, for example, a control unit (not shown) in the television camera via the user interface of the television camera.

  The superimposed video signal generation circuit 15 is controlled by the color comparison circuit 11 and generates a superimposed video signal to be superimposed on the video signal (Y signal) supplied through the matrix circuit 10.

  FIG. 2 is a detailed diagram of the superimposed video signal generation circuit 15. The superimposed video signal generation circuit 15 includes a zebra pattern generation circuit 20 and a switch 21 with control. The zebra pattern generation circuit 20 is a circuit that generates a superimposed video signal that becomes a zebra when displayed on the viewfinder (VF) 17. The zebra pattern generation circuit 20 always generates a superimposed video signal.

  The control-equipped switch 21 is a switch that controls whether or not the color comparison circuit 11 supplies a zebra pattern superimposed video signal to the mixer 16. When the comparison result by the color comparison circuit 11 indicates that the comparison results match, the controlled switch 21 is switched on. When the comparison result indicates that the comparison results do not match, the control-controlled switch 21 is controlled to be switched off. .

  The mixer 16 mixes the superimposed video signal from the superimposed video signal generation circuit 15 with the Y output of the matrix circuit 10. The output of the mixer 16 is supplied to a viewfinder (VF) 17, which can display the mixed video signal.

  The actual operation of the viewfinder display circuit of this embodiment will be described with reference to FIGS.

[Circuit operation]
3 to 6 show an example of the display screen 17 a of the viewfinder (VF) 17. As shown in FIG. 3, it is assumed that there is a screen display of a blue circle or a blue triangle except for a red circle (portion indicated by an arrow) at the bottom of the center of the screen. The “color detection area” is a portion surrounded by a square at the center of the screen. The “color detection area” represented by the square is generated by the color detection frame generation circuit 13. FIG. 3 shows a state before the operation of this circuit in which the blue circle is positioned at the center of the screen and enters the square of the color detection area.

  On the other hand, when the user desires to detect red from the screen display state of FIG. 3, the angle of view of the television camera is moved so that the red circle enters the square of the color detection area at the center of the screen (FIG. 3). 4). Here, the color detection circuit 12 calculates a set value for the video signal in the color detection area located at the center of the display screen.

  For example, the color detection circuit 12 samples the level of the Pr signal in this detection area, for example, 10 times, and converts it into a digital value (decimal number) 200, 202, 204, 199, 200, 201, 200, 200. , 199 and 200 are obtained. For example, the color detection circuit 12 determines a reference value by majority processing that generates the same level, averages these values, or determines a level approximated by a value divided by a predetermined gradation number as a reference value. To do. For example, since these 10 digital values (decimal numbers) are within ± 4 with respect to 200, the color detection circuit 12 can determine almost the same level and can round to 200 values. Therefore, the setting value which is the reference value of the Pr signal determined by the color detection circuit 12 in this case is 200, for example. Such a deviation of the reference value can be arbitrarily selected.

  Similarly, it is assumed that the color detection circuit 12 obtains 10 values of 10, 11, 9, 10, 10, 13, 11, 10, 10, and 9 as digital values (decimal numbers) for the Pb signal. In this case, since it is within ± 3 with reference to 10, it can be determined to be almost the same level and can be rounded to a value of 10. Accordingly, the set value serving as the reference value of the Pb signal determined by the color detection circuit 12 in this case is 10, for example.

  If there is no same value that can be used as a reference value during sampling, a statistical process (with signal levels having the same level as a reference value) is performed after a rounding operation with a deviation in advance. May be. In the example of FIG. 4, since the color entering the square of the color detection area is red, the Pr signal has an overwhelmingly larger value than the Pb signal, and the color detection circuit 12 does not recognize the user visually from the display screen. Color determination can be performed.

  In FIG. 4, the set value of the red circle determined by the color detection circuit 12 is determined to be substantially the same by the color comparison circuit 11 (for example, within a predetermined deviation within ± 5). The superimposed video signal from the generation circuit 15 is generated, and the red circle portion displayed on the viewfinder (VF) 17 is a mixed video signal, that is, a stripe pattern (shown by diagonal lines) as shown in FIG. Become. FIG. 6 shows a case where the red circle is other than the red circle of FIG. The two red circles form a stripe pattern, and the black and white viewfinder can identify the color difference.

  Many variations on the embodiments of the invention are possible. For example, in FIG. 2, a zebra pattern is generated, but if it is difficult to identify with a zebra pattern, a video signal that is not a zebra pattern can be generated and superimposed.

  Further, although the almost same value statistically processed as the reference value of the color signal is used as the reference value, an average value may be calculated for the almost same value.

  Thus, in addition to the above-described embodiments, the present invention can be modified in various ways. Accordingly, the invention is not limited to the embodiments described above, but only by the claims.

  The viewfinder display circuit of the present invention is useful for a broadcast television camera used in a broadcast station. Alternatively, it is also useful when a black and white viewfinder is used in a studio live camera or handy camera.

It is a block diagram of the viewfinder display circuit of one Example by this invention. It is a detailed block diagram of a superimposed video signal generation circuit in a viewfinder display circuit of an embodiment according to the present invention. It is a figure which shows the example of the viewfinder display screen before control of the viewfinder display circuit of one Example by this invention. It is a figure which shows the example of a viewfinder display screen when an angle of view is moved to the color detection area controlled by the viewfinder display circuit of one Example by this invention. It is a figure which shows the example of the viewfinder display screen after control of the viewfinder display circuit of one Example by this invention. It is a figure which shows the example of a viewfinder display screen in case there exist two process targets after control of the viewfinder display circuit of one Example by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Matrix circuit 11 Color comparison circuit 12 Color detection circuit 13 Color detection frame generation circuit 14 Frame on / off switch 15 Superimposition video signal generation circuit 16 Mixer 17 Viewfinder (VF)
17a Viewfinder (VF) display screen

Claims (4)

Conversion means for generating a luminance signal and two kinds of color difference signals from a video signal obtained by processing an imaging signal;
A reference value generating means for performing color determination based on a signal level of the color difference signal in a predetermined color detection area in a display screen displayed by the video signal, and generating a reference value of the signal level subjected to the color determination; ,
A color comparison means that compares the color difference signal with the reference value and determines that they match if they are within a predetermined deviation;
Superimposed image generating means for generating a predetermined superimposed image signal determined in advance;
Mixing means for mixing a luminance signal corresponding to the color difference signal determined to be coincident by the color comparison means and the superimposed video signal of the superimposed video generation means;
A viewfinder display circuit comprising: The viewfinder display circuit according to claim 1,
The superimposed image generation means generates a zebra pattern as a superimposed image signal;
The viewfinder display circuit, wherein the color comparing means controls the output of the generating means when it is determined that the color comparing means agrees. The viewfinder display circuit according to claim 1,
The viewfinder display circuit, wherein the reference value is determined by sampling a signal level of the color difference signal included in the color detection area a plurality of times. The viewfinder display circuit according to claim 1,
The viewfinder display circuit, wherein the color detection area is defined as a settable area located at the center of the display screen.

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