JP2008258786A - Brightness signal generating method and brightness signal generating device, and focus detecting method and focus detecting device in imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brightness signal generating method which can reduce folding back distortion, and generate the brightness signal in good precision in an imaging apparatus which outputs color image data of a Bayer arrangement, and a focus detecting method which can detect focus adjustment detection in good precision. <P>SOLUTION: The brightness signal generating method comprises a plurality of color filters in iteration patterns of 2-pixels in a horizontal direction and 2-pixels in a vertical direction on a plurality of pixels arranged in a matrix shape along the horizontal direction and the vertical direction, outputs pixel signals for every colors through filters, and generates the brightness signals making 4-pixels of the adjoining 2-pixels in the horizontal direction and the adjoining 2-pixels in the vertical direction as a unit corresponding to the output of the pixel signals. When one unit of the brightness signal Y moves in the horizontal direction, the signal is generated for every 4-pixels including 2-pixels of a back column of the vertical columns in a former unit, and when one unit of the brightness signal Y moves in the vertical direction, the signal is generated for every 4-pixels including 2-pixels of a back row of the horizontal rows in a former unit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a luminance signal generation method and a luminance signal generation device for generating a luminance signal in accordance with a digital image signal obtained via an imaging element such as a CCD in an imaging device.

  2. Description of the Related Art Conventionally, an imaging apparatus using an imaging lens that guides a subject image to an imaging device such as a CCD (Charge Coupled Devices), and an imaging device that photoelectrically converts the subject image guided through the imaging lens and outputs an image signal There is a focus detection method in which a luminance signal is generated from an image signal output from an image sensor, and the generated luminance signal is used as an evaluation value for focusing (see, for example, Patent Document 1).

  As for the luminance signal, the image signal formed on the CCD is converted into digital data in synchronization with a predetermined sampling pulse through an AD converter, and a high frequency component is taken out through a high pass filter. It is integrated over the entire evaluation area of the screen and used as an evaluation value for autofocus.

  In autofocus, the imaging lens is moved in the optical axis direction according to the evaluation value described above, and the imaging lens is stopped at the position where the evaluation value is maximized, that is, at the position where the focal points coincide with each other. It is adjusted.

  In addition, the imaging element is configured by a plurality of photoelectric conversion elements in a matrix, and a plurality of color filters are provided on the plurality of photoelectric conversion elements, and the luminance according to the pixel signal of each color output through the color filter A luminance signal generation method for generating the signal (Y) is known.

  For example, in the luminance signal generation method described above, the color filter is configured by a Bayer array including three colors such as R (red), G (green), and B (blue), and R is 1 pixel, G is 2 pixels, and B is 1 In some cases, a unit of four pixels is used as a unit, and a predetermined image region is scanned in the horizontal and vertical directions to generate a luminance signal for each unit (see, for example, Patent Document 2).

In other words, in an imaging device that outputs Bayer color image data, a plurality of color filters are repeated in two vertical and two horizontal pixels on a plurality of pixels arranged in a matrix along the horizontal and vertical directions. A pixel signal for each color is output through a color filter and is provided in a pattern, and in correspondence with the output of the pixel signal, four pixels (R, G) composed of two adjacent horizontal pixels and two vertical pixels , G, and B pixel data) as a unit, a luminance signal is generated.


JP-A-8-317272 JP 2006-293196 A

  According to the conventional luminance signal generation method for Bayer color image data, the sampling interval for each color inevitably becomes longer than the pixel interval, which causes aliasing noise.

  That is, considering the case where there is a change in the luminance level of the high-frequency component in the horizontal direction and no change in the luminance level in the vertical direction, R−Gb = 0 in the vertical difference from the color filter array in FIG. B-Gr = 0. However, in the horizontal difference, R−Gr ≠ 0 and B−Gb ≠ 0, which causes aliasing noise.

  Similarly, in the case where there is a change in the luminance level of the high-frequency component in the vertical direction and no change in the luminance level in the horizontal direction, R-Gr is obtained from the color filter arrangement of FIG. = 0 and B-Gb = 0. However, in the vertical difference, R−Gb ≠ 0 and B−Gr ≠ 0, which causes aliasing noise.

  In addition, when the resolution of the high frequency component detection in the horizontal direction and the vertical direction depends on the sampling pitch and the sampling is performed every four pixels, the frequency of the luminance signal of the subject having the high frequency component is correctly detected. May be insufficient.

  Therefore, the present invention provides a luminance signal generation method capable of reducing aliasing noise and generating a luminance signal with high accuracy, and a focus detection method capable of detecting focus with high accuracy in an imaging apparatus that outputs color image data of a Bayer array. The purpose is to provide.

  In order to achieve this object, the invention according to claim 1 is characterized in that a plurality of color filters are arranged in two horizontal pixels on a plurality of pixels arranged in a matrix along the horizontal direction and the vertical direction. Provided in a repetitive pattern of 2 pixels in the vertical direction, outputs a pixel signal for each color through the filter, and associates 4 pixels of 2 horizontal pixels and 2 vertical pixels with one unit in correspondence with the output of the pixel signal A luminance signal generation method for sequentially generating a luminance signal over a predetermined pixel region, and when the luminance signal moves in the horizontal direction of the pixel region, two pixels in the rear column of the vertical column in the previous unit And is generated every 4 pixels including 2 pixels in the back row of the horizontal row in the previous unit when moving in the vertical direction of the pixel region.

  According to the luminance signal generation method of claim 1, when the luminance signal moves in the horizontal direction of the pixel region, the luminance signal is generated every four pixels including two pixels in the rear row of the vertical column in the previous unit, When moving in the vertical direction of the pixel area, it is generated every 4 pixels including 2 pixels in the back row of the horizontal row in the previous unit. Therefore, when generating a luminance signal in a predetermined image area, every 4 pixels. The sampling frequency can be made higher than the case where the luminance signal is generated by shifting, and even if an image including a high-frequency component is captured, the luminance signal can be generated with high accuracy with little aliasing noise.

  Further, in the luminance signal generation method according to claim 1, as in the invention according to claim 2, the plurality of color filters have G (green) in which one diagonal direction in the four pixels is the same color, and the other When one of the two pixels is R (red) and the other is B (blue), when generating a luminance signal from the RGB color signals, the luminance signal of each color with less aliasing noise. And the resolution of the color image can be improved.

  In addition, the luminance signal generation method according to claim 1 or 2, when generating a luminance signal in a predetermined image area, as in the invention according to claim 3, The first column in the horizontal or vertical direction in the pixel region may be the first column of the pixel column in the first unit without including the two pixels in the rear column.

  The luminance signal generation method according to any one of claims 1 to 3, as in the invention according to claim 4, generates a luminance signal having a predetermined frequency component from the luminance signal generated for each unit. By performing the filtering process so as to extract, it is possible to remove unnecessary frequency components and generate a luminance signal corresponding to a desired frequency component.

  Next, the invention described in claim 5 is a focus detection method for an image pickup apparatus that forms a subject image on an image pickup device, performs photoelectric conversion, and outputs an image signal. A luminance signal is generated using the luminance signal generation method described in the above item, and the luminance signal is used as an evaluation value for focusing on the subject.

  According to the focus detection method in the imaging device according to claim 5, since a luminance signal with little aliasing noise can be used as an evaluation value for focusing even when an image including a high-frequency component is captured, the focus is accurately determined. Can be matched.

  Next, according to a sixth aspect of the present invention, a plurality of color filters are repeated on a pixel arranged in a matrix along the horizontal direction and the vertical direction. And an image sensor that outputs a pixel signal for each color through the filter, and a luminance signal in which four adjacent pixels of two horizontal pixels and two vertical pixels are associated with the output of the pixel signal. A luminance signal generation device including a luminance signal generation unit that sequentially generates over a predetermined pixel area, when the luminance signal generation unit moves in the horizontal direction of the pixel area; When the luminance signal is generated for every four pixels including two pixels in the rear row and moved in the vertical direction of the pixel area, the luminance signal is generated for every four pixels including two pixels in the rear row of the horizontal row in the previous unit. To generate a signal Characterized in that it is configured.

  According to the luminance signal generation device of the sixth aspect, as in the first aspect of the invention, when the luminance signal moves in the horizontal direction of the pixel area, It is generated every 4 pixels including 2 pixels, and when it moves in the vertical direction of the pixel area, it is generated every 4 pixels including 2 pixels in the back row of the horizontal column in the previous unit, so in the predetermined image area When generating a luminance signal, the sampling frequency can be made higher than when generating the luminance signal by shifting every four pixels, and even when an image containing a high-frequency component is captured, a luminance signal with less aliasing noise can be generated.

  According to a sixth aspect of the present invention, in the luminance signal generation device according to the seventh aspect of the present invention, the plurality of color filters are G (green) in which one of diagonal directions of the four pixels is the same color. Thus, when one of the other two pixels is configured to be R (red) and the other is B (blue), when generating the luminance signal from the RGB color signals, Thus, a luminance signal with less aliasing noise can be generated, and the resolution of the color image can be improved.

  Further, in the luminance signal generation device according to claim 6 or 7, as in the invention according to claim 8, the top one unit does not include the two pixels in the back row, and the horizontal or The first column in the vertical direction may be the first column of pixel columns in the first unit.

  Further, in the luminance signal generation method according to any one of claims 6 to 8, as in the invention according to claim 9, a luminance signal having a predetermined frequency component is generated from the luminance signal generated for each unit. By including the filter for extraction, an unnecessary frequency component can be removed and a luminance signal corresponding to a desired frequency component can be generated.

  Next, the invention according to claim 10 is a focus detection apparatus in an imaging apparatus that forms an object image on an image sensor with an imaging optical system and generates and records an image signal representing the object with the image sensor. Luminance signal generating means for generating a luminance signal from an image signal obtained by the image sensor, filter means for extracting a luminance signal in a predetermined frequency region from the luminance signal generated by the luminance signal generating means, and the filter means And a focus evaluation unit that detects a focus degree in accordance with the brightness signal extracted through the brightness signal, and the brightness signal generation unit is any one of claims 6 to 8. And

  According to the focus detection device of the imaging device according to claim 10, since a luminance signal with less aliasing noise can be used as an evaluation value for focusing even when an image including a high frequency component is captured, the focus is accurately determined. Can be matched.

  According to the luminance signal generation method and the luminance signal generation apparatus of the present invention, when the luminance signal moves in the horizontal direction of the pixel area, the luminance signal is generated every four pixels including two pixels in the rear column of the vertical column in the previous unit. When moving in the vertical direction of the area, it is generated every 4 pixels including 2 pixels in the back row of the horizontal row in the previous unit, so when generating a luminance signal in a predetermined image area, it is shifted every 4 pixels. Thus, the sampling frequency can be made higher than that for generating a luminance signal, and even when an image including a high-frequency component is captured, an accurate luminance signal can be generated with less aliasing noise.

  In the luminance signal generation method and the luminance signal generation apparatus according to the present invention, the plurality of color filters have G (green) in which one diagonal direction of four pixels is the same color, and one of the other two pixels is R (red). Since the other is B (blue), when generating a luminance signal from the RGB color signals, it is possible to generate a luminance signal with less aliasing noise for each color and improve the resolution of the color image. it can.

  In addition, the luminance signal generation method and the luminance signal generation apparatus according to the present invention filter unnecessary frequency components by performing a filtering process so as to extract a luminance signal having a predetermined frequency component from the luminance signal generated for each unit. A luminance signal associated with a desired frequency component can be generated by removing the luminance signal.

  Next, since the focus detection method and the focus detection device in the imaging apparatus of the present invention use the luminance signal generation method and the luminance signal generation apparatus of the present invention, even if an image including a high frequency component is captured, aliasing noise is generated. Therefore, it is possible to use a luminance signal with a small amount as an evaluation value for focusing, and it is possible to accurately match the focus.

  Next, an embodiment of a focus detection method and a focus detection apparatus in an imaging apparatus using the brightness signal generation method and the brightness signal generation apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing the procedure of the luminance signal generation method of the present embodiment, FIG. 2 is an explanatory diagram of the luminance signal generation method of the embodiment, and FIG. 3 is a block diagram showing the configuration of the image pickup apparatus of the embodiment.

  As shown in FIG. 3, in this embodiment, the imaging device 1 that captures a subject (imaging signal S) and outputs a digital image signal C, and the digital image signal C input from the imaging device 1 are used. And a focus detection device 15 that detects the degree of focus (parameter for focusing). The focus lens 3 is moved along the optical axis X based on the detected degree of focus, and the focus of the subject image is increased. The position of the focus lens 3 is adjusted so as to match.

  The imaging device 1 includes a front lens 2, a focus lens 3, a filter (which is an infrared filter or an optical filter) 4 that removes harmful infrared rays and harmful reflected light, and an imaging device (CCD: Charge Coupled Devices) 5. AFE (Analog Front End) 6 that converts an analog image signal output from the image sensor 5 into a digital image signal C and outputs it; a TG (Timing Generator) 13 that controls the image sensor 5 and the AFE 6 at a predetermined period; A focus drive unit 12 that performs slide drive of the lens 3 in the optical axis direction, a focus detection unit 10 that detects the slide amount of the focus lens 3 via the sensor 11, and the like are provided.

  The imaging element 5 is configured such that a plurality of photoelectric conversion elements are arranged in a matrix, and the imaging signal S is photoelectrically converted to output an analog image signal for each photoelectric conversion element.

  Further, as shown in FIG. 2A, the image pickup device 5 is a color filter (not shown) composed of a Bayer array of R (red), G (green), and B (blue) in association with the photoelectric conversion device. ), And converts the amount of light that has passed through the filter portions of each color into an electrical signal and outputs it.

  The AFE 6 is a correlated double sampling circuit (CDS: Correlated Double Sampling) 7 that removes noise from the analog image signal output via the image sensor 5, and an image that has been correlated double sampled by the correlated double sampling circuit 7. A variable gain amplifier (AGC) 8 that amplifies the signal, an A / D converter 9 that converts an analog image signal from the image sensor 5 input via the variable gain amplifier 8 into a digital image signal, and the like The image signal configured and output from the image sensor 5 is converted into a digital image signal C at a predetermined sampling frequency and output to the focus detection device 15.

  The imaging device 1 may be configured using a CMOS (Complementary Metal Oxide Semiconductor) sensor instead of the imaging device 5, the correlated double sampling circuit 7, the variable gain amplifier 8, the A / D converter 9, and the like.

  The focus detection device 15 stores a digital image signal C input from the imaging device 1 in association with each pixel address for each RGB color, and a predetermined signal based on the pixel signal stored in the field memory 16. AF (automatic) that stores the output from a luminance signal generation unit 20 that generates a luminance signal in an image area, a CPU (Central Processing Unit) 25, a ROM (Read Only Memory) 26, and an integrator 23 in association with the position of the focus lens. Focus) The evaluation unit 27 and the buffer 28 that temporarily stores the luminance signal generated by the luminance signal generation unit 20, and the like. Each process of the focus detection device 15 is performed by the CPU 25 in accordance with a control program stored in the ROM 26. To control.

  The field memory 16 is associated with the Bayer array, an R field memory 17 that stores a red (R) pixel signal, a G field memory 18 that stores a green (G) pixel signal, and a blue (B) pixel. And a B field memory 19 for storing signals.

  Based on the pixel signal stored in the field memory 16, the luminance signal generation unit 20 generates a luminance signal with four pixels of two adjacent pixels in the horizontal direction and two pixels in the vertical direction as a unit for each predetermined sampling. For focusing by integrating a high-frequency filter (HPF) 22 that extracts a specific frequency component from a luminance signal generated by the luminance calculation unit 21 and a luminance signal generated by the luminance calculation unit 21, and a high-frequency component corresponding to a predetermined pixel area. It is comprised by the integrator 23 output to CPU25 as an evaluation value.

Specifically, as illustrated in FIG. 2B, the luminance calculation unit 21 first generates a luminance signal Y having one unit of four pixels represented by the leading P _0-0 in a predetermined pixel region. Specifically, the luminance signal Y with P _0-0 as one unit in the arithmetic expression of Y = (K ₁ × Gr) + (K ₂ × Gb) + (K ₃ × R) + (K ₄ × B) is Generated. Here, Gr, Gb, R, and B are pixel values associated with the light amounts of the respective pixels, and K _{1 to} K ₄ are predetermined coefficients.

  Further, in the luminance calculation unit 21, when the pixel position when generating the luminance signal Y moves in the horizontal direction of the pixel region, as shown in (b) to (g), the vertical column in the previous unit. It is generated every 4 pixels including 2 pixels in the rear row, and is generated every 4 pixels including 2 pixels in the rear row in the horizontal direction in the previous unit when moving in the vertical direction of the pixel area.

That is, when moving from P _0-0 to P _1-0 , 4 pixels including 2 pixels Gr and Gb in the rear row of the vertical column in the previous unit P _0-0 in P _1-0 are set as one unit. When the luminance signal Y is generated and moves from P _1-0 to P _2-0 , 4 pixels including 2 pixels R and Gb in the vertical rear row in the previous unit P _1-0 in P _2-0 are displayed. A luminance signal Y as one unit is generated.

After the luminance signal Y of the end portion of the horizontal direction in predetermined pixel region is generated, as shown in (e), return to the horizontal start position P _0-1, P _0-1 Oite ago The luminance signal Y having 4 pixels including 2 pixels Gr and B in the horizontal rear row in 1 unit P _0-0 as 1 unit P _0-1 is generated, and then, as shown in (f) and (g), Sequentially, the four pixels P _1-1 and P _2-1 including two pixels in the vertical rear row in one unit in the horizontal direction are read, and the luminance signal Y is generated.

At this time, P _1-1 and P _2-1 include two pixels B and Gb, Gb in the horizontal rear row in P _1-0 and P _2-0 which are one unit in the vertical direction, respectively. And B are included.

  Next, the luminance signal generation unit 20 extracts a specific frequency component from the luminance signal Y generated by the luminance calculation unit 21 through a high-pass filter (HPF) 22, and the extracted high-frequency component is input to the integrator 23. And the result is output to the CPU 25 as an evaluation value for focusing.

  Then, the CPU 25 refers to the output from the integrator 23 and the adjustment value for autofocus stored in the AF evaluation unit 27 in advance, and calculates the position of the focus lens 3 at which the focusing (contrast) is optimal. The focus drive unit 12 is controlled.

  The function of the luminance signal generation means in the present invention is expressed by the field memory 21, the luminance signal generation unit 20, and the like.

  Next, a procedure for generating a luminance signal in the imaging apparatus 1 that outputs Bayer color image data will be described with reference to FIG. This procedure is executed by the CPU 25 giving a command signal to each functional unit based on a program stored in the ROM 26. Further, S in FIG. 1 represents a step.

  First, this procedure starts when an activation signal is input to the imaging device 1 and the focus detection device 15 by the operator.

  Next, as shown in FIG. 1, in S110, the previous data stored in the field memory 21 and the buffer 28 is erased and initialized, and then the process proceeds to S120.

  Next, in S120, the CPU 25 obtains the pixel area for focusing and the reading start position in the pixel area via the ROM 26 based on the photographing condition selected by the operator, and photographs the subject via the imaging device 1. Then, the digital image signal C is read into the field memory 21, and then the process proceeds to S130.

Next, in S130, the first four pixel values of the Bayer array (P _0-0 described in FIG. 2B) are read, and then the process proceeds to S140.

Next, in S140, it generates a luminance signal Y for reading the four pixels _{P 0-0} at S130 as one unit. Specifically, the CPU 25 uses the arithmetic expression Y = (K ₁ × Gr) + (K ₂ × Gb) + (K ₃ × R) + (K ₄ × B) stored in the ROM 26 to calculate P _0. A luminance signal Y having ₋₀ as one unit is generated.

  Next, in S150, the luminance Y generated in S140 is stored in the buffer 28, and then the process proceeds to S160.

  Next, in S160, it is determined whether or not the position of the read pixel has reached the end in the horizontal direction in the pixel area. If it is determined that END (Yes) has reached the end, the process proceeds to S170, while S160. When it is determined that there is a so-called next pixel that has not reached the end (No), the process proceeds to S180. In S180, the readout position is shifted by one pixel in the horizontal direction, and then, the process proceeds to S130. S160 is repeated.

  Next, in S170, it is determined whether or not the position of the pixel to be read has reached the end in the vertical direction in the pixel area, and when it is determined that there is a so-called next read pixel that has not reached the end (No). Shifts to S190, shifts the readout position by one pixel in the vertical direction in S190, and then shifts to S130 and repeats S130 to S170. In S170, it is determined that the vertical pixel position reaches the end. When this occurs, the process of generating the courtesy signal is terminated.

  As described above, the luminance signal generation method and the luminance signal generation in the imaging apparatus 1 described in the present embodiment, as shown in FIG. 2B to FIG. When moving in the horizontal direction, it is generated for every four pixels including two pixels in the rear row of the column in the previous unit. When moving in the vertical direction of the pixel area, two pixels in the rear row of the row in the previous unit. Therefore, when generating the luminance signal Y in a predetermined image area, the sampling frequency can be made higher than when the luminance signal is generated by shifting every four pixels, and the image includes high-frequency components. Even if an image is picked up, it is possible to generate an accurate luminance signal Y with less aliasing noise.

  In addition, the luminance signal generation method and the luminance signal generation apparatus according to the present embodiment extract an unnecessary frequency by extracting the luminance signal Y having a predetermined frequency component from the luminance signal generated for each unit through the high-pass filter 22. The luminance signal Y corresponding to the desired frequency component can be generated by removing the component.

  Further, the focus detection method and the focus detection device 15 in the imaging apparatus 1 according to the present embodiment can use the luminance signal Y with less aliasing noise as the evaluation value for focusing even when an image including a high-frequency component is captured. Therefore, the focus can be matched with high accuracy.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, Various aspects can be taken.

It is a flowchart showing the procedure of the luminance signal generation method of a present Example. FIG. 2 is an explanatory diagram of a luminance signal generation method in the embodiment. It is a block diagram showing the structure of the imaging device of the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Front lens, 3 ... Focus lens, 4 ... Filter, 5 ... Imaging element, 6 ... AFE (Analog Front End), 7 ... Correlated double sampling circuit, 8 ... Variable gain amplifier (AGC: (Automatic Gain Control), 9 ... A / D converter, 10 ... focus detection unit, 11 ... sensor, 12 ... focus drive unit, 13 ... TG (Timing Generator), 15 ... focus detection device, 16 ... field memory, 17 ... R field memory, 18 ... G field memory, 19 ... B field memory, 20 ... luminance signal generation unit, 21 ... luminance calculation unit, 22 ... high pass filter (HPF), 23 ... integrator, 25 ... CPU (Central Processing Unit) 26 ... ROM (Read Only Me) ory), 27 ... AF evaluation unit, 28 ... buffer.

Claims (10)

A plurality of color filters are provided in a repeating pattern of two pixels in the horizontal direction and two pixels in the vertical direction on a plurality of pixels arranged in a matrix along the horizontal direction and the vertical direction,
A pixel signal for each color is output through the filter, and in correspondence with the output of the pixel signal, a luminance signal having four units of two adjacent horizontal pixels and two vertical pixels as one unit is sequentially applied over a predetermined pixel region. A luminance signal generation method for generating,
The luminance signal is
When moving in the horizontal direction of the pixel area, it is generated every 4 pixels including 2 pixels in the back row of the vertical row in the previous unit,
When moving in the vertical direction of the pixel area, it is generated every 4 pixels including 2 pixels in the back row of the horizontal row in the previous unit.
A luminance signal generation method characterized by the above. In the plurality of color filters, one diagonal direction of the four pixels is G (green) having the same color, one of the other two pixels is R (red), and the other is B (blue).
The luminance signal generation method according to claim 1. The first unit does not include the two pixels in the rear column, and the first column in the horizontal or vertical direction in the pixel region is the first column of the pixel columns in the first unit.
The luminance signal generation method according to claim 1, wherein the luminance signal is generated. Filter processing is performed so as to extract a luminance signal having a predetermined frequency component from the luminance signal generated for each unit.
4. The luminance signal generation method according to claim 1, wherein the luminance signal is generated. In an imaging device that forms a subject image on an imaging device, photoelectrically converts it, and outputs an image signal,
A luminance signal is generated using the luminance signal generation method according to any one of claims 1 to 4, and the luminance signal is used as an evaluation value for focusing of the subject image.
A focus detection method in an imaging apparatus. A plurality of color filters are provided in a repeating pattern of two pixels in the horizontal direction and two pixels in the vertical direction on the pixels arranged in a matrix along the horizontal direction and the vertical direction, and pixels for each color are passed through the filter. An image sensor that outputs a signal;
A luminance signal generating means for sequentially generating a luminance signal having four units of two adjacent horizontal pixels and two vertical pixels as one unit in association with the output of the pixel signal over a predetermined pixel region;
With
The luminance signal generating means;
When moving in the horizontal direction of the pixel area, the luminance signal is generated for every four pixels including two pixels in the rear row of the vertical column in the previous unit,
When moving in the vertical direction of the pixel region, the luminance signal is generated for every four pixels including two pixels in the back row of the horizontal row in the previous unit.
A luminance signal generation apparatus characterized by the above. In the plurality of color filters, one diagonal direction of the four pixels is G (green) having the same color, one of the other two pixels is R (red), and the other is B (blue).
The luminance signal generation apparatus according to claim 6. The first unit does not include the two pixels in the rear column, and the first column in the horizontal or vertical direction in the pixel region is the first column of the pixel columns in the first unit.
The luminance signal generation apparatus according to claim 6 or 7, wherein A filter for extracting a luminance signal of a predetermined frequency component from the luminance signal generated for each unit;
9. The luminance signal generation device according to claim 6, wherein the luminance signal generation device is a luminance signal generation device. In a photographing apparatus that forms a subject image on an image sensor with a photographing optical system and generates an image signal representing the subject image with the image sensor.
A luminance signal generating means for generating a luminance signal from an image signal obtained by the imaging element;
Filter means for extracting a luminance signal in a predetermined frequency region from the luminance signal generated by the luminance signal generating means;
Focus evaluation means for detecting a focus degree of focus according to the luminance signal extracted through the filter means;
With
The focus detection device in an imaging apparatus, wherein the brightness signal generation means is the brightness signal generation device according to any one of claims 6 to 9.

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