JPH03205991A - Color video camera - Google Patents

Abstract

PURPOSE:To drop down details only concerning a human face when a figure is photographed by controlling the frequency characteristic of a luminance signal by the output of a hue discriminating circuit. CONSTITUTION:When the (R-Y) and (B-Y) signals of certain hues are inputted to input terminals 2 and 3, an AND circuit 14 of a hue discriminating circuit 1 outputs a high level and while receiving this output, an (f) characteristic control circuit 15 controls the (f) characteristic of the luminance signal inputted from a luminance signal input terminal 16 and outputs the luminance signal to a luminance signal output terminal 17. Therefore, the (f) characteristic of the luminance signal equipped with the hue in an area determined by DC voltages V10-V13 can be dropped down. Thus, soft focus is enabled only concerning the human face when the figure is photographed.

Description

[Detailed Description of the Invention] [Industrial Fields of Application] The present invention is a color system that achieves high image quality by arbitrarily controlling the reproducibility of facial parts and the reproducibility of photographed colors when photographing people, etc. Regarding video cameras.

[Prior Art] The improved image quality of recording and reproducing circuits in color video cameras, VTRs, etc. has made it possible to see even the details of the subject! It has become possible to record and play back images.

As a color video camera of this kind, for example, "Video Salon J" published by Genkosha, May 1989 issue, P. 36.4
Examples include those described in 4.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, when photographing a close-up of a person's face, because of the high resolution, pimples, dirt, etc. on the face are also recorded in detail.

Furthermore, even if the color of the subject is faithfully recorded and reproduced, if the reproduced hue is different from the hue that a person remembers, the user will feel uncomfortable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color video camera that reduces the details of a person's face when photographing a person, and performs correction when the hue of the person's face differs from the hue of the memory color.

[Means for Solving the Problems] The above object is to provide a hue discrimination circuit and a luminance signal frequency control circuit, to make it possible to control the frequency characteristics of the luminance signal of the discriminated hue part, and further to provide a hue error detection circuit and a color correction circuit. A signal addition circuit is provided, and the color signal discriminated by the hue discrimination circuit is
This is achieved by operating the hue error detection circuit and adding a correction signal to the color signal in accordance with the detection signal of the hue error detection circuit.

[Function] The hue discrimination circuit discriminates, for example, the hue within the shaded area in FIG. 2, and controls the frequency characteristics of the luminance signal for that hue.

Thereby, it is possible to control the frequency characteristics of the luminance signal of the subject having the hue within the shaded area in FIG.

Further, the color error detection circuit detects the signal amount of R1B-2Y for the color signal discriminated by the hue discrimination circuit, and the color correction signal addition circuit adds the signal amount of the color signal according to the detected signal amount. Correct with.

As a result, the hue within the shaded area in FIG. 2 can be corrected to a substantially constant hue. [Example] Hereinafter, an example of the present invention will be described using the drawings.

The fourth construction diagram is a block diagram of an embodiment of the large color video camera according to the present invention, in which 1 is a hue discrimination circuit, 2 is (R-
Y) signal input terminal, 3 is (B-Y) signal input terminal, 4 is subtracter, 5 is adder, 6 to 9 is converter, 10 to 1
3 is a DC voltage source and the output voltage of each is V l * t
V ; i y V t x t V l 3 and 14 are AND circuits, 15 is an fvI control circuit, and 16 is a luminance signal input terminal. 17 is a signal output terminal.

The explanation of FIG. 1 will be given below using the fJ2 diagram.

The second country is a diagram showing a cloudy hue on a vectorscope, and the horizontal axis is (B-Y) signal amount. ! The first axis represents the (R-Y) signal amount. The dog in the middle of S represents the color of day. Also, the symbol R in the figure is red. B represents blue, C1 represents cyan, G represents green, and Y represents yellow, indicating the color of the subject.

Self-balanced (p− − y) signal (υIR
4+ )<B-Y) signal (υ(m-Y,), respectively (
(RY) signal input terminal 2 and (B-Y) signal input terminal 3.

The applied (R-Y) signal (υ (R one lesson), (B-Y) signal (υ, car,)) is converted into (R-Y) signal (υ.-3) by the subtracter 4 and adder 5, respectively. , ) and (R+B-2Y) signal (υl1+'!-!▼I).

The comparator 6 receives the input signal υ and the output DC voltage ■1 of the DC voltage source 10. Compare υ,〉■,. When the output is high.

Similarly, comparators 7 to 9 also compare the output DC voltage of each DC voltage source and the input signal υ.

The conditions under which the output of each comparator 6 to 9 becomes high are summarized below.

Comparator 6 υ, 〉v1.

Comparator 7 υ8〈■1, Comparator 8 υs > V t z Comparator 9
υs < V L 3 Therefore, in the circuit of FIG. 1, the condition for the output of the AND circuit 14 to be high is when the following two equations are satisfied.

V. ．． ＜υ＋． ＋＋−＋＋＋＜Vlt−
...-(1) V 1J< v lI1-! l-3Yl
<V 1. ``' (2) The hues limited by the above two equations are the hues indicated by diagonal lines in FIG.

That is, the (R-Y) signal of the hue indicated by this shaded area, (
The B-Y) signal is connected to the (R-Y) signal input terminal 2 in Figure 1 and (
B-Y) When input to the signal input terminal 3, the logic SS circuit 4 outputs a high level.

Upon receiving this output, the f-characteristic control circuit 15 controls the f-characteristic of the luminance signal input from the luminance signal input terminal 16 and outputs a luminance signal to the luminance signal output terminal 17.

Therefore, with this configuration, the DC voltages V r o , V
It is possible to reduce the f characteristic of a luminance signal having a hue within the region defined by t t +VtzyVtz.

Next, specific examples of the f-special control circuit 15 are shown in FIGS. 3, 4, and 5.
As shown in the figure.

FIG. 3 shows an example in which f-characteristic control is performed using a low-pass filter, in which 18 is a resistor, 19 is a capacitor, 20 is a switch, and 16 and 17 are a luminance signal input terminal and an output terminal.

When the switch 20 is on, it operates as a low-pass filter. By controlling the switch 20, the f characteristic can be controlled.

FIG. 4 shows an example in which f-characteristic control is performed by a base clip circuit, where 21 is a base clip circuit, 22 is a switch, 16.
17 is a luminance signal input terminal and an output terminal.

Since the base clip circuit 21 reduces the gain of small signals, by switching the signal path from a to b using the switch 22, the f characteristic of the small signal can be reduced.
By controlling 2, the f characteristic can be controlled.

FIG. 5 is an example in which f-characteristic control is performed using a comb filter,
23 is a delay line that delays the signal for one horizontal scanning period (IH);
4 is an adder, 25 is a switch, and 16 and 17 are luminance signal input terminals and output terminals.

Add the delayed signal obtained by the delay line 23 and the current signal ya
In the signal obtained by the addition in step 24, signal components having no correlation in the vertical direction are suppressed.

Therefore, by switching the signal path from a to b using the switch 25, the f characteristic of a certain portion of the signal that is unrelated to the vertical direction can be dropped, and by controlling the switch 25, the 1' characteristic can be controlled.

Three examples of f-characteristic control circuits have been described above, but in all examples, it is necessary to adjust the signal components that do not control the f-characteristics so that the gain does not change even if the switch 1' is switched.

FIG. 6 is a block diagram showing a second embodiment of the color video camera according to the present invention, in which 26 is a luminance signal input terminal;
7 is a comparator, 28 is a DC voltage source, 29 is an AND circuit, and other symbols are given to the same parts as in the previous embodiment.

The feature of this embodiment is that a w intensity signal amount condition is added to the hue discrimination condition that reduces the f characteristic of the luminance signal.

This luminance signal amount condition takes into consideration that the contrast is reduced because the subject is dark, and the f-characteristic is degraded due to the Percha effect of the imaging optical system. The input H degree signal level is determined by the comparator 27 as the output DC1! of the DC voltage source 28! Pressure V
Compared to Y, the luminance signal level is the output DC voltage v! When the value exceeds a and the hue of the subject is determined to be within the shaded area in FIG. Note that the threshold level of the comparator 27 may be set to 50 to 60'[RE at the I1 degree signal level. According to this embodiment, excessive blurring can be suppressed for dark subjects even if the hue is the same.

FIG. 7 is a structural diagram showing a third embodiment of a color video camera according to the present invention, in which 30 and 31 are sample and hold circuits, 32 to 35 are DC voltage sources, and other symbols are the same as those in the previous embodiment. Identical parts are given the same reference numerals.

The feature of this embodiment is that the f-characteristic of the luminance signal is reduced for the hue selected by the photographer.

First, the hue selection operation will be explained.

? The sample hold circuits 30 and 31 are circuits that sample the signal during the period when the sampling pulse is high and hold it during the IA period when the sampling pulse is low.

Therefore, sample hold time j! 30 holds the (R-B) signal during the high period of the sampling pulse.

Similarly, the sample hold circuit 31 is (R0B-2y)
Figure 8 shows the angle of view for imaging, and by setting the sampling pulse to high for one field period for the shaded area, the average color of the colored print in the shaded area is sampled. , can be held.

The signals held in the sampling hold circuits 30 and 3l in this way are respectively υIII-110. υf
R+! Let l-1■0.

The voltages compared in comparators 6 to 9 are υ■1.

. , υll+1-1. . and DC voltage WX32 to 35 respectively output DC voltage V 3 x + Va 3 t
Since it is the sum of V 34 tV and 6, the hue determined in this example is . Difference signal between (RY) signal and (B-Y) signal? 11-Il+ and sum signal υ111411-■. It is expressed by the following two equations.

υ＋＊−nro Vzz＜υ+x−Bl (υ(z−
．． ．． r o + -V JJ... (3) ri+x+m-x=〉o V34< υ+a+toiy+
O< II tRin-zy+ ++v36
(4) When the hue of the subject satisfies the above conditions, the output of the AND circuit 14 becomes high, and the f-characteristic control circuit 15 reduces the f-characteristic of the luminance signal input from the luminance signal input terminal l6. .

As described above, in this embodiment, it is possible to control the f characteristic of a luminance signal having an arbitrary hue.

FIG. 9 is a block diagram showing a fourth embodiment of a color video camera according to the present invention, in which 36 is a hue error detection circuit;
7 is a color correction signal addition circuit, 38 is a (R-Y) signal input terminal, 39 is a (B-Y) signal input terminal, and 40 is (R-Y)
The signal output terminal 4l is a (B-Y) signal output terminal, and other symbols are the same as those in the previous embodiment.

This embodiment lowers the f-characteristic of the luminance signal of the hue portion of a specific area and at the same time corrects the hue within the specific area. The specific area discrimination circuit in this embodiment is the same as in the previous embodiment, and its explanation will be omitted here.

In addition, the hue is basically corrected by reducing the signal amount ΔS of (R1B-2Y). The color difference error detection circuit 36 calculates ΔS only during the period when the output of the AND circuit 14 is high,
The calculated signal is output to the color correction signal addition circuit 37.

The color correction signal addition circuit 37 receives (R-Y) (B-
Y) Added the signal and ΔS and performed color correction (R-Y)'
(B-Y)' signal is output.

As a specific example, a case will be described in which all of the determined hues are corrected on the (R-B) axis on a vectorscope.

In this case, the signal ΔS, which is orthogonal to the (R-B) axis, is (
R+B-2Y), the color correction addition circuit 37 calculates (
(RY) signal υ<<, - input from the R-Y) signal input terminal 38. The hue was corrected by ΔS (R-Y
)'signal υ+x−v》' Correction coefficients α, β
Perform the following calculation using .

υ{λ−▼) ' ” 11 tilk−41+α゜Δ
S ------- (5) Also, the following equation is obtained for the (B-Y} signal in the same manner.

υ{3～! ｝′8υ《ト▼｝＋β゜ΔS ゜″−=(6
)-1 However, in reality, forcing the hues to match is rather unsightly, so it is better to apply a weaker correction.

Also, it is preferable that the hue to be corrected is slightly greener than the (R-B) axis, and the (R-y) signal for ΔS generation and (
It is advantageous to make the addition ratio of the (RY) signal slightly larger than that of the (RY) signal.

As described above, in this embodiment, the hue can be corrected for a subject having a specific hue.

[Effects of the Invention] As explained above, according to the present invention, it is possible to reduce the f-characteristic of the luminance signal for a specific colored hat, so when the person w1 is in the shadow, only the person's face, etc. can be soft-focused. Furthermore, by adding the level information of the luminance signal to the hue determination, it is possible to suppress excessive soft focus when photographing people.

Additionally, by manually setting the hue discrimination criteria, it is possible to soft-focus on the hue area that the photographer is aiming for.

Furthermore, since the hue can be corrected only for a specific hue, it is also possible to match the hue of the subject to the hue of a human's memory color.

As described above, the present invention can eliminate the problems of the prior art described above and provide a color video camera with excellent functions.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of a color video camera according to the present invention, Fig. 2 is a diagram showing hue on a vector scope, and Figs. 3, 4, and 5 are f-special control diagrams. circuit 15
6 is a block diagram showing a second embodiment of the color video camera according to the present invention, and FIG. 7 is a block diagram showing a third embodiment of the color video camera according to the present invention.
FIG. 8 is a diagram showing a 100-angle image taken, and FIG. 9 is a configuration diagram showing a fourth embodiment of a color video camera according to the present invention. 1... Irota's discrimination circuit, 6 to 9... Converter,
14...AND circuit, l5...f special control circuit, 30
, 3l... Sample hold circuit, 36... Hue error detection circuit, 37... Color correction signal addition circuit.

Claims (1)

[Scope of Claims] 1. A color video camera characterized by being provided with a frequency control circuit that controls the frequency characteristics of a luminance signal based on the output of a hue discrimination circuit that discriminates the hue of an input color signal. 2. The color video camera according to claim 1, wherein the frequency characteristic control circuit is a low-pass filter. 3. The color video camera according to claim 1, wherein the frequency characteristic control circuit is a base clip circuit. 4. The color video camera according to claim 1, wherein the frequency characteristic control circuit is constructed using a delay line that delays a signal for one horizontal scanning period. 5. The color video camera according to claim 1, wherein the output of the hue discrimination circuit is output according to the level of the luminance signal. 6. The color video camera according to claim 1, wherein the hue discrimination circuit is provided with a sampling and holding circuit for a designated color signal to use the signal as a reference for hue discrimination. 7. A frequency control circuit that controls the frequency characteristics of the luminance signal based on the output of the hue discrimination circuit that discriminates the hue of the input color signal, and a hue error detection circuit that detects hue errors from the input color signal. A color video camera comprising a color correction signal addition circuit that adds a correction signal output to a color signal.