JP2004173207A - Signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a luminance signal with higher quality and to suppress generation of moire due to chromatic aberration. <P>SOLUTION: This signal processor has an Out of Green luminance circuit (5) which outputs a luminance signal 1 by an Out of Green system based on an inputted image signal, a Switch Y luminance circuit (6) which outputs a luminance signal 2 by a Switch Y system based on the inputted image signal, a mixing ratio changing circuit (7) which determines ratio for mixing the luminance signals 1, 2 and a luminance mixing circuit (8) which mixes the luminance signals 1, 2 according to the ratio determined by the mixing ratio changing circuit. <P>COPYRIGHT: (C)2004,JPO

Description

【００２６】
のように演算する。次に、混合比率演算回路１７において、距離ｄにより混合比率ｒを演算する。例えば、画像中心から最も距離の離れた画素位置までの距離をＤｍａｘとすると、
ｒ ＝ ｄ／Ｄｍａｘ …（４）
のように演算する。このようにすると、中心付近では混合比率ｒが０となり、周辺で１となる。
また、距離ｄと混合比率ｒの関係を図５のように作成しておき、テーブル変換によって距離ｄから混合比率ｒを求めるように構成してもよい。
【００２７】
輝度混合回路８では、上記混合比率ｒを用いて、輝度信号１と輝度信号２を次式（５）のように混合して混合輝度信号Ｙｍｉｘを得る。なお、式（５）において、輝度信号１はＹ１、輝度信号２はＹ２、比率ｒは輝度信号１の混合比率を示すものとする。従って、輝度信号２の混合比率は（１−ｒ）により表される。
Ｙｍｉｘ ＝ ｒＹ１ ＋ （１−ｒ）Ｙ２ …（５）
【００２８】
図６は、図５に示す比率を用いて、輝度混合回路８により輝度信号１及び輝度信号２を混合した結果を図示したものである。中央部ではＳｗｉｔｃｈ Ｙ方式の輝度が採用され、周辺ではＯｕｔ Ｏｆ Ｇｒｅｅｎ方式の輝度、中間部では両方式の輝度を混合した輝度が採用されている。
【００２９】
以上のように構成することで、画像の中心部分と周辺部分で異なる方式の輝度信号を採用することが可能となり、レンズ系の色収差の影響を受けにくい輝度信号を作成することが可能となる。
【００３０】
即ち、本第１の実施形態によれば、入力した画像信号に基づいて、第１の方式により第１の輝度信号を生成し、同じ画像信号に基づいて、第２の方式により第２の輝度信号を生成し、第１及び第２の輝度信号を混合する割合を決定し、決定した割合に応じて、第１及び第２の輝度信号を混合する。
【００３１】
より具体的には、混合する割合を決定する時には、画像信号の画像における位置を検出し、検出した位置に基づいて、混合する割合を決定する。
【００３２】
更に具体的には、前記第１の方式は、Ｏｕｔ ｏｆ Ｇｒｅｅｎ方式であって、前記第２の方式は、Ｓｗｉｔｃｈ Ｙ方式である。
【００３３】
＜第２の実施形態＞
本第２の実施形態では、第１の実施形態に加え、さらに、画像の特定個所のみ複数の輝度信号を混合することが可能な実施形態について説明する。
【００３４】
第１の実施形態では、輝度信号１と輝度信号２を被写体によらず、画像の中心からの距離に応じて混合していたが、色の濃い被写体の場合、輝度信号の色構成比の違いにより輝度レベルが異なってくる。例えば、（Ｒ，Ｇ，Ｂ）＝（２００，０，０）という色の場合、色の構成比がＲ：Ｇ：Ｂ＝３：６：１の場合、Ｙ＝６０くらいになるが、色の構成比がＲ：Ｇ：Ｂ＝１：２：１の場合、Ｙ＝５０くらいになる。そのため、色の濃い被写体を撮影した場合、輝度信号１と輝度信号２の輝度レベルの差が激しくなり、切り替えポイントでの輝度段差が気になる場合がある。
【００３５】
これを避けるためには、色の濃い部分については、輝度信号を混合せずに、Ｏｕｔ ｏｆ Ｇｒｅｅｎ方式で得られた輝度信号１をそのまま用いる。
【００３６】
図７は、本第２の実施形態における撮像装置の構成を示すブロック図である。図７では、図１の構成に信号処理装置４’内に混合位置検出回路１８が加わったもので、その他の構成は図１と同じであるため、同じ構成については詳細説明を省略する。以下、本第２の実施形態における動作を、図８のフローチャートを参照しながら説明するが、第１の実施形態で説明した図２のフローチャートの処理と同様の処理には同じ参照番号を付し、一部説明を省略する。
【００３７】
信号処理装置４は、ＷＢ回路３によりＷＢ処理された信号を受け取とると（ステップＳ１１）、Ｏｕｔ ｏｆ Ｇｒｅｅｎ輝度回路５において、Ｏｕｔ ｏｆ Ｇｒｅｅｎ方式により輝度信号１を作成し（ステップＳ１２）、ＳｗｉｃｈＹ輝度回路６により、ＳｗｉｃｈＹ方式により輝度信号２を作成する（ステップＳ１３）。その後、入力した信号の彩度から、輝度信号混合を行うか否かを判断するが（ステップＳ２１）、この判断は混合位置検出回路１８で行われる。
【００３８】
図９は、本第２の実施形態における混合位置検出回路１８の構成例を示すブロック図である。まず、彩度演算回路１９において、例えば、次式（６）に従って彩度を演算する。なお、式（６）のＣｈｍは、彩度である。
【００３９】

【００４０】
次に、混合度合い決定回路２０において、ある閾値より彩度が小さい場合にのみ輝度を混合するように決定する。例えば、閾値ＴＨとＣｈｍを比較し、Ｃｈｍの方が小さい場合には輝度を混合すると判定し、１の信号を発生する。逆の場合にはしないと判定し、０の信号を発生する。
【００４１】
輝度混合回路８’において、この信号を受け取り、１が与えられた場合のみ、輝度の混合を実施するよう構成する（ステップＳ１４〜Ｓ１６）。なお、輝度の混合は、上記第１の実施形態で説明したようにして行われる。０の場合には、Ｏｕｔ ｏｆ Ｇｒｅｅｎ方式で得られた輝度信号１を出力する。
【００４２】
上記の通り第２の実施形態によれば、彩度が小さい部分のみ輝度の混合が実施されるため、上記問題を回避することが可能となる。
【００４３】
なお、上記第２の実施形態では、混合するかしないかを彩度と閾値とを比較して０、１で判定したが、彩度に応じて０〜１の連続的な数値で混合度合いを決定するように構成してもよい。
【００４４】
即ち、本第２の実施形態によれば、上記第１の実施形態の構成に加えて、画像信号の彩度に応じて、第１及び第２の輝度信号を混合するか否かを判断し、混合すると判断した場合に、第１及び第２の輝度信号を混合する。
【００４５】
より具体的には、上記判断を行う時に、画像信号の彩度を検出し、検出した彩度を予め決められた閾値と比較し、閾値よりも小さい場合に第１及び第２の輝度信号を混合し、大きい場合に前記第１及び第２の輝度信号を混合しないと決定する。
【００４６】
また、別の構成では、上記第１の実施形態の構成に加えて、前記画像信号の彩度に応じて、第１及び第２の輝度信号を混合する割合を判断し、上記決定された２種類の割合に応じて、第１及び第２の輝度信号を混合する。
【００４７】
より具体的には、前記第１の方式は、Ｏｕｔ ｏｆ Ｇｒｅｅｎ方式であって、彩度に基づく判断で混合しないと判断した場合に、第１の輝度信号をそのまま出力する。
【００４８】
【他の実施形態】
なお、本発明は、複数の機器（例えばホストコンピュータ、インターフェイス機器、スキャナ、カメラヘッドなど）から構成されるシステムに適用しても、一つの機器からなる装置（例えば、デジタルスチルカメラ、デジタルビデオカメラ、複写機、ファクシミリ装置など）に適用してもよい。
【００４９】
また、本発明の目的は、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。ここでプログラムコードを記憶する記憶媒体としては、例えば、フレキシブルディスク、ハードディスク、ＲＯＭ、ＲＡＭ、磁気テープ、不揮発性のメモリカード、ＣＤ−ＲＯＭ、ＣＤ−Ｒ、ＤＶＤ、光ディスク、光磁気ディスク、ＭＯなどが考えられる。
【００５０】
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。
【００５１】
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、先に説明した図２または図８に示す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。
【００５２】
【発明の効果】
上記の通り本発明によれば、より質の高い輝度信号を得ると共に、色収差によるモアレの発生を抑制することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態における撮像装置の概略構成を示すブロック図である。
【図２】本発明の第１の実施形態における輝度信号生成手順を示すフローチャートである。
【図３】本発明の第１の実施形態におけるＯｕｔ ｏｆ Ｇｒｅｅｎ輝度回路の構成例を示すブロック図である。
【図４】本発明の第１の実施形態における混合比率変更回路の構成例を示すブロック図である。
【図５】本発明の第１の実施形態における中心から各画素までの距離に対する、混合比率の例を示す図である。
【図６】本発明の第１の実施形態における輝度信号１及び輝度信号２を混合した結果を示す図である。
【図７】本発明の第２の実施形態における撮像装置の構成を示すブロック図である。
【図８】本発明の第２の実施形態における輝度信号生成手順を示すフローチャートである。
【図９】本発明の第２の実施形態における混合位置検出回路の構成例を示すブロック図である。
【図１０】原色ベイヤー配列を示す図である。
【図１１】Ｓｗｉｔｃｈ Ｙ方式の説明図である。
【図１２】Ｓｗｉｔｃｈ Ｙ方式で輝度信号生成を行う回路の構成例を示すブロック図である。
【図１３】色収差を説明するための図である。
【符号の説明】
１ 撮像素子
２ Ａ／Ｄ変換回路
３ ホワイトバランス回路
４、４’ 信号処理装置
５ ＯｕｔｏｆＧｒｅｅｎ輝度回路
６ ＳｗｉｃｈＹ輝度回路
７ 混合比率変更回路
８、８’ 輝度混合回路
９ Ｒ補間回路
１０ Ｂ補間回路
１１ Ｇ補間回路
１２ 輪郭補正回路
１３ 乗算回路
１４ 加算回路
１５ 画素位置検出回路
１６ 距離演算回路
１７ 混合比率演算回路
１８ 混合位置検出回路
１９ 彩度演算回路
２０ 混合度合い決定回路
１０１ 射出瞳
１０２ 固体撮像素子
１２０１ ベース信号補間回路
１２０２ 高域強調回路
１２０３ 加算器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to signal processing, and more particularly to processing for creating a luminance signal from an output signal from an image sensor having a plurality of color filters.
[0002]
[Prior art]
Conventionally, as a method of creating a luminance signal based on an output color signal from a solid-state imaging device, a SwitchY method and an OutofGreen method are known. Hereinafter, these methods will be described by taking as an example a case where the solid-state imaging device is covered with a color filter having a primary color Bayer array as shown in FIG.
[0003]
The SwitchY system is a system in which an output signal from a solid-state imaging device is A / D converted, and a signal subjected to white balance (hereinafter, WB) processing is regarded as a luminance signal Y as it is. FIG. 11 is a diagram showing the concept of the obtained luminance signal Y, and the number after Y indicates the position of a pixel. Also, in order to suppress generation of carriers due to sampling, a result obtained by applying a low-pass filter (hereinafter, LPF) having an output of 0 at the Nyquist frequency in each of the horizontal direction and the vertical direction is used as a base signal. For example, if the filter coefficient of the LPF is [1 2 1] in both the horizontal and vertical directions, the output Y22 ′ from the LPF of the pixel Y22 is
Y22 ′ = (Y11 + 2 × Y12 + Y13 + 2 × Y21 + 4 × Y22 + 2 × Y23 + Y31 + 2 × Y32 + Y33) / 16 (1)
[0004]
You can ask as follows.
Further, as shown in FIG. 12, a high-frequency emphasis signal is generated by the high-rank bellflower town circuit 1202 from the base signal obtained from the base signal interpolation circuit 1201, and the original base signal is added by the adder 1203, thereby obtaining a high-frequency signal. Can be obtained.
[0005]
However, in an actual imaging system, a lens system is arranged before the solid-state imaging device, and light passing through the lens system is sampled by the solid-state imaging device. Since chromatic aberration occurs in light that has passed through the lens system, the sampling position differs depending on the color near the image.
[0006]
This phenomenon will be described with reference to FIG. In FIG. 1, reference numeral 101 denotes an exit pupil of a lens system; and 102, a solid-state imaging device such as a CCD. FIG. 13 shows light from the exit pupil 101 to the image forming plane. For example, the solid line shows blue and the broken line shows red light. At the center of the image, as shown in FIG. 13A, the center of gravity of the sampling does not change even if chromatic aberration occurs, whereas at the periphery of the image, the sampling position differs depending on the color as shown in FIG. 13B.
[0007]
Therefore, especially at the periphery of the image, the position of the image to be sampled is different for each color of the image sensor, so that moire due to the sampling position shift occurs. For example, in the case of the filter arrangement as shown in FIG. 10, the sampling positions at the R position and the B position are substantially shifted with respect to the G position, and an interference pattern is generated in the image.
[0008]
[Problems to be solved by the invention]
As described above, since light passing through the lens system has chromatic aberration, even if the arrangement of the solid-state imaging devices is at equal intervals, sampling is shifted substantially depending on the color of the color filter, and moiré is generated. Had occurred.
[0009]
The present invention has been made in view of the above problems, and has as its object to obtain a higher quality luminance signal and to suppress the occurrence of moire due to chromatic aberration.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a signal processing device according to the present invention comprises: a first luminance signal generation unit that outputs a first luminance signal in a first method based on an input image signal; A second luminance signal generating unit that outputs a second luminance signal according to a second method based on the signal; a mixing ratio determining unit that determines a mixing ratio of the first and second luminance signals; A mixing unit that mixes the first and second luminance signals in accordance with the ratio determined by the mixing ratio determination unit.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
<First embodiment>
In the first embodiment, a signal from a single-chip image sensor covered with a color filter of a primary color Bayer array composed of three colors of R (red), G (green), and B (blue) shown in FIG. The case where a luminance signal is obtained will be described below.
[0013]
FIG. 1 is a block diagram illustrating a schematic configuration of the imaging apparatus according to the first embodiment of the present invention. The imaging device includes, for example, a digital still camera or a digital video camera, but is not limited to this, and electrically converts an incident optical image by photoelectric conversion using a two-dimensionally arranged solid-state imaging device such as an area sensor. The present invention can be applied as long as the image is obtained.
[0014]
In FIG. 1, reference numeral 1 denotes an image sensor (hereinafter, referred to as a CCD) such as a CCD that photoelectrically converts incident light and outputs an electric signal, 2 denotes an A / D conversion circuit, 3 denotes a white balance (WB) circuit, Is a signal processing device. In the above configuration, a signal output from the CCD 1 is converted into a digital signal by the A / D conversion circuit 2, and a signal subjected to a known white balance (WB) process by the WB circuit 3 is input to the signal processing device 4. In FIG. 1, for the sake of simplicity, a gamma conversion circuit, a color creation circuit, and the like, which are not directly related to the present invention, are omitted.
[0015]
Next, the configuration and operation of the signal processing device 4 according to the first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 2 is a flowchart showing a luminance signal generation procedure in the first embodiment.
[0016]
As shown in FIG. 1, the signal processing device 4 includes an OutofGreen luminance circuit 5, a SwitchY luminance circuit 6, a mixture ratio changing circuit 7, and a luminance mixture circuit 8. When the signal processing device 4 receives the signal subjected to the WB processing by the WB circuit 3 (step S11), the Out of Green luminance circuit 5 creates the luminance signal 1 by the Out of Green method (step S12).
[0017]
FIG. 3 is a block diagram illustrating a configuration example of the Out of Green luminance circuit 5 according to the first embodiment. An R interpolation circuit 9, a B interpolation circuit 10, and a G interpolation circuit 11 are provided to independently process R, B, and G signals corresponding to each color filter position of the CCD 1. For example, when processing an R signal, 0 is inserted into pixels other than R, and the same applies to a G signal and a B signal by applying an LPF having a coefficient of [1 2 1] in each of the horizontal and vertical directions. And the multiplication circuit 13 and the addition circuit 14 generate a luminance signal Y as in the following equation.
Y = 0.3R + 0.59G + 0.11B (2)
[0018]
Further, a high-frequency emphasized signal is created from the G signal by the contour correction circuit 12 and added to Y. As described above, since the high-frequency emphasis signal is created from only the G signal, the G signal is dominant in the luminance signal Y.
[0019]
On the other hand, the luminance signal 2 is created by the SwitchY luminance circuit 6 by, for example, the SwitchY method described in the related art (step S13). Note that the SwitchY system is a system in which a red (R) signal, a green (G) signal, and a blue (B) signal are regarded as a luminance signal as they are, and an image of a primary color Bayer array used in the first embodiment is taken. In the case of the element, the color composition ratio of luminance is R: G: B = 1: 2: 1.
[0020]
In the luminance signal 2 obtained by the Switch Y method, as described in the conventional example, the moire is remarkably generated around the image. On the other hand, since the luminance signal 1 based on the Out of Green method forms a luminance signal around the G signal as described later, even if the sampling positions of the R signal and the B signal are shifted with respect to the G signal due to chromatic aberration, Less susceptible. However, the Out of Green method uses only about half of the pixels of the CCD as compared to the Switch Y method, and therefore, it is more advantageous to use the Switch Y method at the center of the image.
[0021]
Therefore, in the first embodiment, the Switch Y method is used at the center of the image, the Out of Green method is used around the image, and both the Switch Y method and the Out of Green method are used at the middle of the image.
[0022]
The mixing ratio changing circuit 7 changes the mixing ratio between the luminance signal 1 and the luminance signal 2 according to the pixel position (step S14). More specifically, the mixing ratio r is determined according to the distance d from the center (or optical axis) of the screen to each pixel. How to determine the mixing ratio will be described later in detail.
[0023]
Next, in the luminance mixing circuit 8, the luminance signal 1 and the luminance signal 2 are mixed using the mixing ratio r changed by the mixing ratio changing circuit 7 (step S16). This mixing method will be described later in detail.
[0024]
FIG. 4 is a block diagram illustrating a configuration example of the mixture ratio changing circuit 7 according to the first embodiment. First, the pixel position (x, y) being processed by the pixel position detection circuit 15 is detected. Next, the distance from the image center (xc, yc) is calculated by the distance calculation circuit 16. For example, if the distance d is

[0026]
Is calculated as follows. Next, the mixture ratio calculation circuit 17 calculates the mixture ratio r from the distance d. For example, if the distance from the image center to the pixel position furthest from the image is Dmax,
r = d / Dmax (4)
Is calculated as follows. In this case, the mixing ratio r becomes 0 near the center and becomes 1 near the center.
Alternatively, the relationship between the distance d and the mixture ratio r may be created as shown in FIG. 5 and the mixture ratio r may be determined from the distance d by table conversion.
[0027]
In the luminance mixing circuit 8, the luminance signal 1 and the luminance signal 2 are mixed using the mixing ratio r as in the following equation (5) to obtain a mixed luminance signal Ymix. In Equation (5), the luminance signal 1 indicates Y1, the luminance signal 2 indicates Y2, and the ratio r indicates the mixing ratio of the luminance signal 1. Therefore, the mixing ratio of the luminance signal 2 is represented by (1-r).
Ymix = rY1 + (1-r) Y2 (5)
[0028]
FIG. 6 illustrates a result of mixing the luminance signal 1 and the luminance signal 2 by the luminance mixing circuit 8 using the ratio shown in FIG. The luminance of the Switch Y system is adopted in the center, the luminance of the Out Of Green system is adopted in the periphery, and the luminance obtained by mixing the luminances of both systems is adopted in the middle.
[0029]
With the above-described configuration, it is possible to adopt different types of luminance signals in the central part and the peripheral part of the image, and it is possible to create a luminance signal that is less affected by chromatic aberration of the lens system.
[0030]
That is, according to the first embodiment, the first luminance signal is generated by the first method based on the input image signal, and the second luminance signal is generated by the second method based on the same image signal. A signal is generated, a ratio of mixing the first and second luminance signals is determined, and the first and second luminance signals are mixed according to the determined ratio.
[0031]
More specifically, when determining the mixing ratio, the position of the image signal in the image is detected, and the mixing ratio is determined based on the detected position.
[0032]
More specifically, the first method is an Out of Green method, and the second method is a Switch Y method.
[0033]
<Second embodiment>
In the second embodiment, in addition to the first embodiment, an embodiment in which a plurality of luminance signals can be mixed only at a specific portion of an image will be described.
[0034]
In the first embodiment, the luminance signal 1 and the luminance signal 2 are mixed according to the distance from the center of the image regardless of the subject. However, in the case of a subject with a dark color, the difference in the color composition ratio of the luminance signal is different. , The brightness level differs. For example, in the case of a color of (R, G, B) = (200, 0, 0), when the color composition ratio is R: G: B = 3: 6: 1, Y = about 60. Is about 50 when the composition ratio of R: G: B = 1: 2: 1. Therefore, when an image of a dark-colored subject is captured, the difference between the luminance levels of the luminance signal 1 and the luminance signal 2 becomes large, and the luminance step at the switching point may be a concern.
[0035]
In order to avoid this, the luminance signal 1 obtained by the Out of Green method is used as it is without mixing the luminance signals for the dark portion.
[0036]
FIG. 7 is a block diagram illustrating a configuration of an imaging device according to the second embodiment. In FIG. 7, a mixed position detecting circuit 18 is added to the signal processing device 4 'in the configuration of FIG. 1, and the other configuration is the same as that of FIG. 1. Therefore, detailed description of the same configuration will be omitted. Hereinafter, the operation in the second embodiment will be described with reference to the flowchart of FIG. 8, but the same processes as those in the flowchart of FIG. 2 described in the first embodiment are denoted by the same reference numerals. And a part of the description is omitted.
[0037]
When the signal processing device 4 receives the signal subjected to the WB processing by the WB circuit 3 (step S11), the Out of Green luminance circuit 5 creates the luminance signal 1 by the Out of Green method (step S12), and the SwitchY luminance. The luminance signal 2 is created by the circuit 6 according to the SwitchY method (step S13). Thereafter, it is determined whether or not to perform luminance signal mixing based on the saturation of the input signal (step S21). This determination is performed by the mixed position detection circuit 18.
[0038]
FIG. 9 is a block diagram illustrating a configuration example of the mixed position detection circuit 18 according to the second embodiment. First, the saturation calculation circuit 19 calculates the saturation according to, for example, the following equation (6). Note that Chm in Expression (6) is saturation.
[0039]

[0040]
Next, the mixing degree determination circuit 20 determines to mix the luminance only when the saturation is smaller than a certain threshold. For example, the threshold value TH is compared with Chm, and if Chm is smaller, it is determined that luminance is mixed, and one signal is generated. In the opposite case, it is determined not to be performed, and a signal of 0 is generated.
[0041]
The luminance mixing circuit 8 'is configured to receive this signal and perform luminance mixing only when 1 is given (steps S14 to S16). The mixing of the luminance is performed as described in the first embodiment. In the case of 0, the luminance signal 1 obtained by the Out of Green method is output.
[0042]
As described above, according to the second embodiment, since the mixing of the luminance is performed only in the portion where the saturation is low, the above problem can be avoided.
[0043]
In the second embodiment, whether or not mixing is performed is determined by comparing the saturation with a threshold value and determining whether the mixing is 0 or 1. However, according to the saturation, the mixing degree is determined by a continuous numerical value of 0 to 1. It may be configured to determine.
[0044]
That is, according to the second embodiment, in addition to the configuration of the first embodiment, it is determined whether to mix the first and second luminance signals according to the saturation of the image signal. When it is determined that the luminance signals are mixed, the first and second luminance signals are mixed.
[0045]
More specifically, when performing the above-described determination, the saturation of the image signal is detected, the detected saturation is compared with a predetermined threshold, and the first and second luminance signals are determined when the saturation is smaller than the threshold. It is determined that the first and second luminance signals are not mixed when they are mixed and large.
[0046]
In another configuration, in addition to the configuration of the first embodiment, the ratio of mixing the first and second luminance signals is determined in accordance with the saturation of the image signal, and the determined 2 The first and second luminance signals are mixed according to the type ratio.
[0047]
More specifically, the first method is an Out of Green method, and outputs a first luminance signal as it is when it is determined that mixing is not to be performed based on the saturation.
[0048]
[Other embodiments]
Note that the present invention is applicable to a system including a plurality of devices (for example, a host computer, an interface device, a scanner, a camera head, etc.), but is not limited to a single device (for example, a digital still camera, a digital video camera). , Copiers, facsimile machines, etc.).
[0049]
Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (or a CPU or a CPU) of the system or the apparatus. Needless to say, the present invention can also be achieved by an MPU) reading and executing a program code stored in a storage medium. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program code, 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 part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing. Here, examples of the storage medium for storing the program code include a flexible disk, a hard disk, a ROM, a RAM, a magnetic tape, a nonvolatile memory card, a CD-ROM, a CD-R, a DVD, an optical disk, a magneto-optical disk, and an MO. Can be considered.
[0050]
Further, 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 of the program is performed based on the instruction of the program code. It goes without saying that the CPU included in the expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0051]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts shown in FIG. 2 or FIG.
[0052]
【The invention's effect】
As described above, according to the present invention, a higher-quality luminance signal can be obtained, and the occurrence of moire due to chromatic aberration can be suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of an imaging device according to a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating a luminance signal generation procedure according to the first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration example of an Out of Green luminance circuit according to the first embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration example of a mixture ratio changing circuit according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating an example of a mixing ratio with respect to a distance from a center to each pixel according to the first embodiment of the present invention.
FIG. 6 is a diagram illustrating a result of mixing the luminance signal 1 and the luminance signal 2 according to the first embodiment of the present invention.
FIG. 7 is a block diagram illustrating a configuration of an imaging device according to a second embodiment of the present invention.
FIG. 8 is a flowchart illustrating a luminance signal generation procedure according to the second embodiment of the present invention.
FIG. 9 is a block diagram illustrating a configuration example of a mixed position detection circuit according to a second embodiment of the present invention.
FIG. 10 is a diagram showing a primary color Bayer array.
FIG. 11 is an explanatory diagram of a Switch Y system.
FIG. 12 is a block diagram illustrating a configuration example of a circuit that generates a luminance signal by a Switch Y method.
FIG. 13 is a diagram for explaining chromatic aberration.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 imaging device 2 A / D conversion circuit 3 white balance circuit 4, 4 ′ signal processing device 5 OutofGreen luminance circuit 6 SwitchY luminance circuit 7 mixing ratio changing circuit 8, 8 ′ luminance mixing circuit 9 R interpolation circuit 10 B interpolation circuit 11 G Interpolation circuit 12 contour correction circuit 13 multiplication circuit 14 addition circuit 15 pixel position detection circuit 16 distance calculation circuit 17 mixing ratio calculation circuit 18 mixing position detection circuit 19 saturation calculation circuit 20 mixing degree determination circuit 101 exit pupil 102 solid-state image sensor 1201 base Signal interpolation circuit 1202 High frequency emphasis circuit 1203 Adder

Claims (1)

First luminance signal generating means for outputting a first luminance signal based on the input image signal by a first method;
A second luminance signal generation unit that outputs a second luminance signal in a second method based on the input image signal;
Mixing ratio determining means for determining a ratio of mixing the first and second luminance signals;
A signal processing device comprising: a mixing unit that mixes the first and second luminance signals in accordance with the ratio determined by the mixing ratio determination unit.

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