JPH02214272A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To improve the focusing sensitivity in the case of pickup of a person by detecting a skin signal from a video signal, increasing the high frequency component to the skin color signal more than the other part, weighting the result and focusing a focus device to the skin color. CONSTITUTION:A window comparator 23 acts on a specific area A of a color difference signal R-Y, a window comparator 24 acts on a specific area B of a color difference signal B-Y, and they act on a prescribed region. Thus, an AND circuit 25 detects an area satisfying the levels A, B simultaneously, that is, a skin color area C. A skin color signal outputted from the AND circuit 25 is inputted to a gain variable circuit 26, which is set to have a large gain when the skin color signal is entered and the gain of a high frequency component of the skin color in a luminance signal Y is increased more than the gain of the high frequency component of the other part. Thus, the weighting of the skin color part is increased and the device is surely focused to a person.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an automatic focusing device for a video camera.

[Conventional technology]

FIG. 2 shows the configuration of a conventional automatic focusing device, which detects a high frequency component of a video signal and focuses so that this high frequency component is maximized.

In the figure, 1 is a lens with a focusing mechanism, 2 is an image sensor, 3 is a preamplifier, 4 is a camera signal processing circuit, and 5 is an R-
Y signal output terminal, 6 is a B-Y signal output terminal, 7 is a Y signal output terminal, 8 is a band pass filter, 9 is a detection circuit, 1
0 is a control circuit, and 11 is a motor drive circuit.

Next, the operation will be explained. An image from a subject passes through a lens 1, is imaged onto an image sensor 2, and is photoelectrically converted.

The photoelectrically converted electric signal is amplified by the preamplifier 3, white balance γ correction, matrix processing, etc. are performed by the camera signal processing circuit 4, and three baseband signals, RY signal, RY signal, A B-Y signal and a Y signal are output.

RY and B-Y are color difference signals, and Y is a luminance signal. The R degree signal Y has a wide band. A focusing device using a video signal extracts a high frequency component from this broadband luminance signal Y and controls it so that this high frequency component is maximized. However, the band pass filter 8 extracts this high frequency component. However, in order to remove unnecessary lock components, a bandpass filter is used here. The high frequency component extracted by the bandpass filter 8 is detected by a detection circuit 9, and controlled by a control circuit 10 so that the output of the detection circuit 9 is maximized. The motor drive circuit 11 receives the output of the control circuit 1O and drives the focusing mechanism of the lens 1. In this way, automatic focusing is performed so that the high frequency component of the video signal is maximized.

[Problem to be solved by the invention]

In the conventional apparatus described above, control is performed so that the high frequency component is maximized no matter what kind of subject it is. For this reason, the camera sometimes focuses on a different subject than the intended subject, making it extremely difficult to use.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain an automatic focusing device that can reliably focus on a human subject when the subject is a human.

[Means for Solving the Problems] An automatic focusing device according to the present invention includes means for detecting a skin-colored portion of a video signal, and a means for detecting a skin-colored portion of a video signal, and a means for detecting a high-frequency component of the skin-colored portion of the video signal from a high-frequency component of other portions. A means to increase the size is provided.

[For production]

In this invention, the high frequency component of the video signal is detected and the skin color part is detected, the high frequency component of this skin color part is made larger than the high frequency component of other parts, and the focusing mechanism is set so that the high frequency component is maximized. is driven.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of the automatic focusing device according to this embodiment.
Each of the 11 parts is the same as that shown in FIG. 20 is a variable gain section inserted between the bandpass filter 8 and the detection circuit 9, and includes clamp circuits 21, 22, window comparator circuits 23. 24, AND circuit 25 and variable gain circuit 2
Consists of 6.

Next, the operation will be explained. In the band-pass filter 8, the zero color difference signals R-Y and B-Y for extracting high frequency components of the luminance signal Y are input to clamp circuits 21 and 22, and the DC potential is fixed, as in the conventional band pass filter 8. Window comparator 2
3 and 24 detect that this fixed DC potential is in a specific potential region. FIG. 3 shows the skin color as a vector, where the 0 part indicates the skin color area.The window comparator 23 reacts in a specific area A of the color difference signal RY, and the window comparator 24 responds to a specific area A of the color difference signal B-Y. It reacts in region B and therefore in the region indicated by the dotted line in each case.

Therefore, the AND circuit 25 detects a region that satisfies the levels A and B simultaneously, that is, a skin color region C. The skin color signal output from the AND circuit 25 is input to the variable gain circuit 26, and the variable gain circuit 26 is set to increase the gain when the skin color signal is input. The gain of the high frequency component is larger than the gain of high frequency components of other parts. Therefore, it is possible to increase the weighting of the skin-colored portion, and it is possible to increase the focusing sensitivity for the high-frequency components of the skin-colored portion. Therefore, when capturing an image of a human, the human can be reliably focused.

Note that a gate circuit may be used instead of the variable gain circuit 26, and in this case, if the gate is opened when the AND circuit 25 outputs, it is possible to react only to the skin-colored portion.

〔Effect of the invention〕

As described above, according to the present invention, a skin color signal is detected from a video signal, and this skin color signal is weighted by making its high frequency component larger than other parts, and the focusing mechanism focuses on the skin color part. Focused. Therefore, when photographing a person, it is possible to reliably focus on the person, and the focus sensitivity can be improved.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an automatic focusing device according to the present invention;
The figure is a configuration diagram of a conventional device, and FIG. 3 is a vector diagram of skin colors. DESCRIPTION OF SYMBOLS 1... Lens, 2... Lifting element, 8... Band pass filter, 11... Motor drive circuit, 2o... Variable gain part. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa 3rd RY ＞C1＞ α■ Procedural amendment

Claims (1)

[Claims] means for detecting a high frequency component of a video signal; means for detecting a skin color portion of the video signal; means for making the high frequency component of the skin color portion of the video signal larger than the high frequency component of other portions; and the high frequency component. 1. An automatic focusing device comprising a driving means for driving a focusing mechanism so that the focusing mechanism is maximized.