JP4208563B2 - Automatic focus adjustment device - Google Patents

Description

のような２×２のフィルタがかけられ、輝度信号が作成される。
【００３２】
(ステップＳ５)
輝度信号作成ブロック１０４からの輝度信号に、測距エリア１ライン毎にバンドパスフィルタ１０５をかける。なお、本実施形態では、回路を簡略化するために、１ライン毎のバンドパスフィルタとしているが、ディレイラインを設定して３ライン、５ラインとライン数を増やし、２次元のバンドパスフィルタをかけるほうがより正確なコントラスト信号が得られる。
【００３３】
(ステップＳ６)
図５のようにバンドパスフィルタ後の信号より、PeakHold回路１０６により回路絶対値のピーク信号を保持し、測距エリア内の全ての水平ラインのピーク信号の和を算出し、これを第１のコントラスト信号とする。なお、ピーク信号の和でなく、バンドパスフィルタ出力の絶対値の積分値を用いてもよい。
【００３４】
(ステップＳ７)
一方、色信号作成ブロックにて、ホワイトバランス後の信号を、色マトリクス回路１０７にてＲ−Ｙ、Ｂ−Ｙ信号に変換する。
【００３５】
(ステップＳ８)
測距エリア内の色差信号を加算平均する。
【００３６】
次に、本実施形態の特徴点である、コントラスト信号補正部の説明をする。
【００３７】
ステップＳ６からの第１のコントラスト信号と、ステップＳ８からの色差信号を用いて、コントラスト補正を実施する。これは、被写体が人の顔などの場合は、コントラスト信号が弱くなってしまうのを防ぐためである。色差信号から肌色を検出し、肌色と判定された場合は、第１のコントラスト信号を強調するゲインをかける。以下に、このコントラスト信号補正部を詳細に説明する。
【００３８】
(ステップＳ９)
測距エリア内の色差信号の平均(aveＲ−Ｙ、aveＢ−Ｙ)を算出し、
ChromaHue＝tan^-1（（aveＲ−Ｙ）／（aveＢ−Ｙ））
の式で色相角(ChromaHue)を作成する。この演算は、肌色相角検出回路１０８により行なわれる。
【００３９】
(ステップＳ１０)
図３のような色差空間上で、予め設定した肌色の色相角（ChromaSkin）とChromaHueが同じ場合にGainＭＡＸとし、肌色の色相角から離れるにつれ補正ゲイン（ContrastCorrectGain）を小さくし、予め設定した色相角（θTh）以上離れるとゲインをGainMin(＝１)とするコントラスト補正ゲインを出力する。この演算は、補正ゲイン算出回路１０９により行なわれる。
【００４０】
例えば、
０＝|ChromaHue−ChromaSkin|
のとき、
ContrastCorrectGain＝GainＭＡＸ(＝２.０)
θTh≦|ChromaHue−ChromaSkin|
のとき、
ContrastCorrectGain＝GainMin(＝１.０)
θTh＞|ChromaHue−ChromaSkin|＞０
のとき、
ContrastCorrectGain＝ａ×|ChromaHue−ChromaSkin|＋b
の線形１次式で算出する。
【００４１】
更に、本実施形態では、よりＡＦ検出の精度を向上させるために、コントラスト補正ゲインの最大値GainＭＡＸを、フォーカスレンズ位置によって変化させる。これは、主に人物撮影などの場合、被写体は比較的近い距離に存在する場合が多いため、ＡＦステップの近側のGainＭＡＸを無限側のGainＭＡＸより大きい値に設定する。例えば、図４のような特性をもつグラフを用いて、ＡＦステップ位置によってGainＭＡＸを変化させる。
【００４２】
(ステップＳ１１)
コントラスト信号補正部（色変換ＭＴＸ回路１０７、肌色相角検出回路１０８、補正ゲイン算出回路１０９を備える）より算出された補正ゲインをコントラスト検出部（Ｙ−ＬＰＦ回路１０４、ＢＰＦ１０５、PeakHold回路１０６を備える）からの第１のコントラスト信号にかける（乗算器１１１により行なわれる）ことにより肌補正後の第２のコントラスト信号を作成する。
【００４３】
(ステップＳ１２)
複数のＡＦステップ位置によって得られた第２のコントラスト信号のピーク値を検出し、合焦位置判定回路１１３によりそのポイントを合焦ポイントと判断し、フォーカスレンズ１０１を移動する。なお、コントラスト信号のピーク信号ではなく、ピークから任意の数のステップポイントを選択し、その平均を合焦位置と判断してもよい。
【００４４】
上述のように、本実施形態によれば、人物等を撮影して顔面の映像が低コントラスト状態になった場合でも、肌色の色相角を判別し、肌と判定されたコントラスト信号を強調するコントラスト補正部を備えているため、より正確なオートフォーカスが実現できる。
【００４５】
また、本実施形態では、ステップＳ８、Ｓ９により、測距エリア内の色差信号の平均値を算出し、その色差信号からの色相角でコントラスト補正ゲインを求め、各ステップ毎に算出されたコントラスト信号を補正しているが、各ステップの各水平ライン毎に求めたバンドパスピーク信号に、各ライン毎に算出した色相角よる肌補正ゲインをかけ、その補正コントラスト信号の積分値（測距エリア内）を用いて合焦位置を判定してもよい。
【００４６】
以上説明したように、上記の実施形態によれば、予め決められたステップでフォーカスレンズを近側から無限側まで動かしながら被写体を複数枚撮影し、その撮像信号から輝度信号と色信号を作成し、輝度信号より合焦判定用の高周波信号を検出し、色信号から被写体が肌色であった場合に、前記合焦用高周波信号のゲインをアップする構成をとるため、人物の顔アップなどの場合に、合焦判定用高周波信号の振幅を大きくすることが可能となり、より正確なオートフォーカスが実現できる。
【００４７】
【他の実施形態】
本発明は、複数の機器から構成されるシステムに適用しても良いし、また、単体の機器から成る装置に適用しても良いしＬＡＮなどのネットワークを介して処理が行われるシステムに適用しても良い。
【００４８】
また、各実施形態の目的は、前述した実施形態の機能を実現するソフトウェアのプログラムコードを記録した記憶媒体（または記録媒体）を、システムあるいは装置に供給し、そのシステムあるいは装置のコンピュータ（またはＣＰＵやＭＰＵ）が記憶媒体に格納されたプログラムコードを読み出し実行することによっても、達成されることは言うまでもない。この場合、記憶媒体から読み出されたプログラムコード自体が前述した実施形態の機能を実現することになり、そのプログラムコードを記憶した記憶媒体は本発明を構成することになる。また、コンピュータが読み出したプログラムコードを実行することにより、前述した実施形態の機能が実現されるだけでなく、そのプログラムコードの指示に基づき、コンピュータ上で稼働しているオペレーティングシステム（ＯＳ）などが実際の処理の一部または全部を行い、その処理によって前述した実施形態の機能が実現される場合も含まれることは言うまでもない。
【００４９】
さらに、記憶媒体から読み出されたプログラムコードが、コンピュータに挿入された機能拡張カードやコンピュータに接続された機能拡張ユニットに備わるメモリに書込まれた後、そのプログラムコードの指示に基づき、その機能拡張カードや機能拡張ユニットに備わるＣＰＵなどが実際の処理の一部または全部を行い、その処理によって前述した実施形態の機能が実現される場合も含まれることは言うまでもない。
【００５０】
本発明を上記記憶媒体に適用する場合、その記憶媒体には、先に説明したフローチャートに対応するプログラムコードが格納されることになる。
【００５１】
【発明の効果】
以上説明したように、本発明によれば、人物等を撮影した場合でも精度のよいオートフォーカスを可能とすることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態におけるＡＦ制御ブロックの回路の概略図である。
【図２】一実施形態の合焦装置の動作フローチャートである。
【図３】肌色判定および補正ゲイン設定を示した図である。
【図４】ＭＡＸゲインの設定例を示した図である。
【図５】バンドパスフィルタの出力波形を示す図である。
【図６】撮像エリアと測距エリアを示した図である。
【符号の説明】
１０１ フォーカスレンズ群
１０２ ＣＣＤ撮像素子
１０３ ホワイトバランス回路
１０４ 輝度ノッチ回路
１０５ バンドパスフィルタ
１０６ ピークホールド、高周波信号検出回路
１０７ 色変換マトリクス回路
１０８ 色相角検出回路
１０９ 高周波信号補正ゲイン算出回路
１１１ ゲイン回路（乗算回路）
１１２ メモリ
１１３ 合焦位置判定ブロック
１１４ フォーカスレンズ駆動部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic focus adjustment technique in an imaging apparatus.
[0002]
[Prior art]
In general, in an electronic image pickup apparatus having a two-dimensional image pickup device such as a digital camera or a video camera, the sharpness of the screen is detected from the video signal of the subject, and the position of the focusing lens is controlled so as to maximize this sharpness. The method of focusing is used. This sharpness detection method uses the intensity of the high-frequency component of the video signal extracted by the bandpass filter, or the detection intensity of the blur width at the edge of the subject obtained by differentiating the video signal by a differentiation circuit or the like. It is done.
[0003]
When a normal subject is photographed, the sharpness is small when the subject is out of focus, increases as the subject is in focus, and reaches a maximum value when the subject is completely in focus. Conventionally, the focusing lens is controlled by moving the focusing lens as fast as possible in the direction of increasing sharpness when the sharpness is small, and gradually decreasing the speed as it increases, and focusing on the top of the sharpness mountain. So-called hill-climbing autofocus (hereinafter abbreviated as hill-climbing AF) that stops the lens with high accuracy is generally used.
[0004]
As another control means, the focus lens position is gradually moved from the near end to the infinite end before the actual photographing, and the subject is photographed each time, and the plurality of images are passed through the sharpness detecting means. Of the sharpness obtained in this way, the all-scanning AF using the focus lens position where the image having the highest sharpness as the focus point is used is used.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional AF (autofocus) method, for example, when the most general person is photographed as a normal subject, for example, when a face-up image is present in the distance measurement area, the face is However, since the image signal in the distance measurement area is in a low contrast state, the focusing lens cannot be accurately stopped at the focal point. This is mainly because the change in the sharpness signal of the low-contrast subject is small with respect to the amount of movement of the focusing lens.
[0006]
Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to enable accurate autofocus even when a person or the like is photographed.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, an automatic focus adjustment apparatus according to the present invention captures a subject image while moving a focus lens for adjusting a focus state of the subject image on an image sensor. Imaging means for generating an image signal, a high-frequency signal from the output signal of the imaging means, and a focus position determination means for determining a focus position of the focus lens based on the detected high-frequency signal; Skin color detection means for detecting a skin color from the output signal of the imaging means, the skin color detection means calculates a hue angle from the color signal from the image sensor, and is within a preset hue angle range of the skin color. If the skin color detection means detects the skin color, the focus position determination means determines the high-frequency signal based on the difference between the subject hue angle and a preset skin color hue angle. It is characterized by emphasizing the Inn.
Also, the control method of the automatic focus adjustment apparatus according to the present invention is an imaging means for capturing an image of a subject and generating an image signal while moving a focus lens for adjusting the focus state of the subject image on an image sensor. A skin color detection step of calculating a hue angle from a color signal from the image sensor and detecting that the skin color is within a preset hue angle range of the skin color; In the focus position determination step of detecting a high frequency signal from the output signal of the imaging means and determining the focus position of the focus lens based on the detected high frequency signal, and in the focus position determination step, the skin color when the detecting means detects the skin color, chromatic and emphasizing enhancement step by a gain based on the difference between skin color hue angle of the high-frequency signal set in advance as the object hue angle It is characterized in Rukoto.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described.
[0009]
First, an outline of the present embodiment will be described.
[0010]
The automatic focus adjustment apparatus of this embodiment shoots a subject image for each step while moving the focus lens in predetermined steps while adjusting the focus state of the subject image on the image sensor. Imaging means for generating a plurality of image signals, signal processing means for creating a luminance signal and a color signal from the output signal of the imaging means, and high-frequency signal detection for detecting a first high-frequency signal from the luminance signal Means for detecting skin color from the color signal, gain determining means for determining a gain to be multiplied by the first high-frequency signal based on a detection result of the skin color detecting means, and the gain determining means. Multiplying means for multiplying the first high-frequency signal by the determined gain and outputting a second high-frequency signal; and a focus position of the focus lens based on the second high-frequency signal And a focus position determining means for determining.
[0011]
In the automatic focus adjustment apparatus of the present embodiment, it is preferable that the high-frequency signal detection unit includes a band pass filter and outputs a peak value of an absolute value of the output of the band pass filter.
[0012]
In the automatic focus adjustment apparatus of the present embodiment, it is preferable that the high-frequency signal detection unit includes a band-pass filter and outputs a sum of absolute values of outputs of the band-pass filter.
[0013]
In the automatic focus adjustment apparatus of the present embodiment, the skin color detection unit calculates a hue angle from a color signal from the image sensor, and detects that the skin color is within a preset hue angle range of the skin color. It is preferable.
[0014]
In the automatic focus adjustment apparatus of the present embodiment, the gain determination unit may calculate a correction gain based on a difference between a subject hue angle obtained from the skin color detection unit and a preset skin color hue angle. preferable.
[0015]
Further, the automatic focus adjustment method of the present embodiment shoots the subject image at each step while moving the focus lens for adjusting the focus state of the subject image on the image sensor in a predetermined step, An imaging step of generating a plurality of image signals, a signal processing step of creating a luminance signal and a color signal from an output signal in the imaging step, a high-frequency signal detection step of detecting a first high-frequency signal from the luminance signal, A skin color detection step for detecting a skin color from the color signal, a gain determination step for determining a gain to be multiplied by the first high-frequency signal based on a detection result in the skin color detection step, and a gain determination step A multiplication step of multiplying the first high-frequency signal by a gain and outputting a second high-frequency signal; and an in-focus position of the focus lens based on the second high-frequency signal Determining and a focus position determination step.
[0016]
In the automatic focus adjustment method of the present embodiment, it is preferable that the peak value of the absolute value of the output of the bandpass filter is output in the high-frequency signal detection step.
[0017]
In the automatic focus adjustment method of the present embodiment, it is preferable that the high-frequency signal detection step outputs the sum of the absolute values of the output of the bandpass filter.
[0018]
Further, in the automatic focus adjustment method of the present embodiment, in the skin color detection step, a hue angle is calculated from a color signal from the image sensor, and if it is within a preset hue angle range of the skin color, the skin color is detected. It is preferable.
[0019]
In the automatic focus adjustment method of the present embodiment, in the gain determination step, a correction gain is calculated based on a difference between a subject hue angle obtained in the skin color detection step and a preset skin color hue angle. preferable.
[0020]
In addition, the program according to the present embodiment causes a computer to execute the above automatic focus adjustment method.
[0021]
Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.
[0022]
FIG. 1 is a schematic diagram of a circuit of an AF (autofocus) control block in an imaging apparatus according to an embodiment. A rough operation of the AF apparatus will be described with reference to FIG.
[0023]
Light from a subject (not shown) passes through a lens 101 including a focus lens group and forms an image on the CCD image sensor 102. In the output signal from the CCD 102, the gain of each color filter is adjusted by a white balance (WB) block 103. The Y-LPF block 104 applies an appropriate LPF (low pass filter) to the signal output from the white balance block 103 to limit the band, and a BPF (band pass filter) circuit 105 is provided for each horizontal line. A high frequency signal is detected at. Next, the peak value of the output signal of the BPF circuit 105 is output by the peak hold circuit 106 for each horizontal line, and this becomes the first high-frequency signal.
[0024]
On the other hand, the signal output from the white balance block 103 is converted into color difference signals Cr and Cb by a color conversion MTX (matrix) circuit 107, and a flesh color angle detection block 108 detects whether the skin color or flesh color. The gain applied to the first high-frequency signal is determined by the correction gain calculation block 109 based on the output of the skin hue angle detection block 108.
[0025]
Next, the first high-frequency signal is corrected by the multiplier 111 to become a second high-frequency signal, which is once recorded in the memory 112. The above-described high-frequency signal is generated and recorded in the memory in all horizontal lines in the preset distance measuring area, and the sum of the high-frequency signals of all the lines is obtained.
[0026]
The focus lens driving unit 114 calculates the sum of the high frequency signals at all AF step points (points at which the focus lens can move), and then selects the step point with the highest sum of the high frequency signals in the focus position determination block 113. The focus lens is determined to be in focus, and the focus lens driving unit 114 moves the focus lens to the focus position. Thereafter, actual photographing (not described in this specification) is started.
[0027]
FIG. 2 is an operation flowchart of the AF apparatus. Hereinafter, the details of the operation of the AF apparatus will be described with reference to FIGS. 1 and 2.
[0028]
(Step S1)
When the shutter is half-pressed, the focus lens driving unit 114 that drives the position of the focus lens 101 moves the focus lens in a preset step from the near end to the infinite end.
[0029]
(Step S2)
At each step (each moving position of the focus lens), the subject is photographed, and an imaging signal in a distance measuring area set in advance as shown in FIG. (Hereafter, it will be performed for all signals taken at each step)
(Step S3)
A white balance gain is applied to each color filter in the white balance block 103.
[0030]
(Step S4)
In the luminance signal generation block (Y-LPF circuit) 104, in order to correct the sensitivity variation of the color filter, for example,
[Expression 1]

The 2 × 2 filter is applied to create a luminance signal.
[0032]
(Step S5)
The bandpass filter 105 is applied to the luminance signal from the luminance signal generation block 104 for each line of the ranging area. In this embodiment, in order to simplify the circuit, a band-pass filter for each line is used. However, a delay line is set to increase the number of lines to three lines and five lines, and a two-dimensional band-pass filter is used. A more accurate contrast signal can be obtained by applying.
[0033]
(Step S6)
As shown in FIG. 5, the peak hold circuit 106 holds the peak signal of the circuit absolute value from the signal after the bandpass filter, calculates the sum of the peak signals of all the horizontal lines in the distance measurement area, and uses this as the first signal. A contrast signal is used. Note that the integrated value of the absolute value of the bandpass filter output may be used instead of the sum of the peak signals.
[0034]
(Step S7)
On the other hand, in the color signal generation block, the signal after white balance is converted into RY and BY signals by the color matrix circuit 107.
[0035]
(Step S8)
Addition and averaging of the color difference signals in the distance measurement area.
[0036]
Next, the contrast signal correction unit, which is a feature point of the present embodiment, will be described.
[0037]
Contrast correction is performed using the first contrast signal from step S6 and the color difference signal from step S8. This is to prevent the contrast signal from becoming weak when the subject is a human face or the like. A skin color is detected from the color difference signal, and when it is determined to be a skin color, a gain for enhancing the first contrast signal is applied. Hereinafter, the contrast signal correction unit will be described in detail.
[0038]
(Step S9)
Calculate the average (aveR-Y, aveBY) of the color difference signals in the distance measurement area,
ChromaHue = tan ^-1 ((aveRY) / (aveBY))
Create a hue angle (ChromaHue) with the formula This calculation is performed by the skin hue angle detection circuit 108.
[0039]
(Step S10)
In the color difference space as shown in Fig. 3, when the preset skin color hue angle (ChromaSkin) and ChromaHue are the same, Gain MAX is set, and as the skin color hue angle is moved away, the correction gain (ContrastCorrectGain) is decreased and the preset hue angle is set. When the distance is greater than (θTh), a contrast correction gain with a gain of GainMin (= 1) is output. This calculation is performed by the correction gain calculation circuit 109.
[0040]
For example,
0 = | ChromaHue−ChromaSkin |
When,
ContrastCorrectGain = GainMAX (= 2.0)
θTh ≦ | ChromaHue−ChromaSkin |
When,
ContrastCorrectGain = GainMin (= 1.0)
θTh> | ChromaHue-ChromaSkin |> 0
When,
ContrastCorrectGain = a × | ChromaHue−ChromaSkin | + b
The linear primary expression is calculated.
[0041]
Furthermore, in this embodiment, in order to further improve the accuracy of AF detection, the maximum value GainMAX of the contrast correction gain is changed according to the focus lens position. This is because the subject is often located at a relatively close distance mainly in the case of human photography or the like, so that the gain MAX on the near side of the AF step is set to a value larger than the gain MAX on the infinite side. For example, using a graph having characteristics as shown in FIG. 4, GainMAX is changed according to the AF step position.
[0042]
(Step S11)
The correction gain calculated by the contrast signal correction unit (including the color conversion MTX circuit 107, the skin hue angle detection circuit 108, and the correction gain calculation circuit 109) is used as the contrast detection unit (including the Y-LPF circuit 104, the BPF 105, and the PeakHold circuit 106). ) Is applied to the first contrast signal (performed by the multiplier 111) to create a second contrast signal after skin correction.
[0043]
(Step S12)
The peak value of the second contrast signal obtained by a plurality of AF step positions is detected, the focus position determination circuit 113 determines that point as the focus point, and the focus lens 101 is moved. Instead of the peak signal of the contrast signal, an arbitrary number of step points may be selected from the peak, and the average may be determined as the in-focus position.
[0044]
As described above, according to the present embodiment, even when a person or the like is photographed and the facial image is in a low contrast state, the hue angle of the skin color is determined, and the contrast that enhances the contrast signal determined to be skin is enhanced. Since the correction unit is provided, more accurate autofocus can be realized.
[0045]
In the present embodiment, the average value of the color difference signals in the distance measurement area is calculated in steps S8 and S9, the contrast correction gain is obtained from the hue angle from the color difference signals, and the contrast signal calculated for each step is calculated. However, the bandpass peak signal obtained for each horizontal line in each step is multiplied by the skin correction gain based on the hue angle calculated for each line, and the integrated value of the corrected contrast signal (in the distance measurement area) ) May be used to determine the in-focus position.
[0046]
As described above, according to the embodiment described above, a plurality of subjects are photographed while moving the focus lens from the near side to the infinity side in predetermined steps, and a luminance signal and a color signal are generated from the imaging signals. When a high-frequency signal for focus determination is detected from the luminance signal and the subject is flesh-colored from the color signal, the gain of the focus high-frequency signal is increased, so that the face of a person is raised In addition, the amplitude of the high-frequency signal for focus determination can be increased, and more accurate autofocus can be realized.
[0047]
[Other Embodiments]
The present invention may be applied to a system composed of a plurality of devices, may be applied to an apparatus composed of a single device, or may be applied to a system in which processing is performed via a network such as a LAN. May be.
[0048]
In addition, an object of each embodiment is to supply a storage medium (or recording medium) on which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and a computer (or CPU) of the system or apparatus Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0049]
Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0050]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.
[0051]
【The invention's effect】
As described above, according to the present invention, accurate autofocus can be achieved even when a person or the like is photographed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a circuit of an AF control block according to an embodiment of the present invention.
FIG. 2 is an operation flowchart of the focusing apparatus according to the embodiment.
FIG. 3 is a diagram illustrating skin color determination and correction gain setting.
FIG. 4 is a diagram illustrating a setting example of a MAX gain.
FIG. 5 is a diagram showing an output waveform of a bandpass filter.
FIG. 6 is a diagram illustrating an imaging area and a ranging area.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 Focus lens group 102 CCD image pick-up element 103 White balance circuit 104 Luminance notch circuit 105 Band pass filter 106 Peak hold, high frequency signal detection circuit 107 Color conversion matrix circuit 108 Hue angle detection circuit 109 High frequency signal correction gain calculation circuit 111 Gain circuit (multiplication) circuit)
112 Memory 113 Focus position determination block 114 Focus lens drive unit

Claims (4)

Imaging means for capturing an image of a subject and generating an image signal while moving a focus lens for adjusting a focus state of the subject image on an image sensor;
A focus position determination unit that detects a high-frequency signal from an output signal of the imaging unit and determines a focus position of the focus lens based on the detected high-frequency signal;
Skin color detecting means for detecting skin color from the output signal of the imaging means,
The flesh color detecting means calculates a hue angle from a color signal from the image sensor, detects that the flesh color is within a preset hue angle range of the flesh color,
The in-focus position determination unit emphasizes the high-frequency signal with a gain based on a difference between a subject hue angle and a preset skin color hue angle when the skin color detection unit detects a skin color. Adjusting device.   2. The automatic focusing apparatus according to claim 1, wherein the high-frequency signal is a peak value of an absolute value of an output of a bandpass filter.   2. The automatic focusing apparatus according to claim 1, wherein the high-frequency signal is an output of a sum of absolute values of outputs of a bandpass filter. A method of controlling an automatic focus adjustment apparatus including an imaging unit that captures a subject image while moving a focus lens for adjusting a focus state of the subject image on an image sensor, and generates an image signal,
A skin color detection step of calculating a hue angle from a color signal from the image sensor and detecting a skin color if within a preset hue angle range of the skin color;
A focus position determination step of detecting a high frequency signal from the output signal of the imaging means and determining a focus position of the focus lens based on the detected high frequency signal;
In the in-focus position determination step, when the skin color detection means detects a skin color, the high frequency signal has an enhancement step of enhancing the high frequency signal with a gain based on a difference between the subject hue angle and a preset skin color hue angle. A control method of an automatic focusing device characterized by

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