JP5109529B2 - Imaging device - Google Patents

Description

  The present invention relates to a focus adjustment signal generation device that generates an image signal for manual focus adjustment and displays the image signal on a viewfinder, a liquid crystal display element, or the like, and a video camera or electronic device including the focus adjustment signal generation device. The present invention relates to an imaging apparatus such as a still camera.

  In recent video cameras and electronic still cameras, the resolution of captured images is increasing. On the other hand, the size of a viewfinder (hereinafter referred to as VF), a liquid crystal display element (LCD), or the like for a photographer to check a photographed image is limited for carrying the camera. Therefore, the resolution that can be displayed by the VF is often insufficient compared to the resolution of the captured image, and it has become difficult for the photographer to adjust the focus while viewing the image displayed on the VF.

  Therefore, a focus adjustment signal generation device that easily adjusts the focus with an easy-to-view image even when using the VF or LCD as described above is disclosed (for example, see Patent Document 1). The device described in Patent Document 1 performs image processing on the contour (edge) of a subject and displays it on a VF or LCD. In this apparatus, three primary color signals (hereinafter referred to as RGB signals) of an R signal (red), a G signal (green), and a B signal (blue) are generated from a luminance signal extracted from an input subject image signal. Then, the high frequency component in the horizontal direction, the high frequency component in the vertical direction, and the high frequency component in the oblique direction are separately output from the luminance signal by the frequency filter means. Further, the R signal and the high-frequency component in the horizontal direction, the G signal (green) and the high-frequency component in the vertical direction, and the B signal (blue) and the high-frequency component in the diagonal direction are respectively added to the image portion of the high-frequency component. The color is colored.

  That is, according to the focus adjustment signal generating device described in Patent Document 1, a predetermined color is displayed on the edge portion of the monochrome image of the subject displayed on the VF or LCD. By adjusting the focus so that a predetermined color of the edge portion becomes dark, the focus is adjusted in a direction in which the edge portion becomes sharp. Therefore, the focus can be easily adjusted with an easy-to-see image.

JP 2006-58683 A

  By the way, when the resolution of the image signal obtained by imaging is different from the resolution of the viewer for displaying it, the high frequency component is lost when the focus adjustment signal is generated after down-conversion. Therefore, the focus adjustment signal is not generated accurately. Accordingly, it is necessary to generate a focus adjustment signal before down-conversion processing. When the resolution is different, for example, a high-definition high-definition (hereinafter referred to as HD) signal obtained by imaging is down-converted and displayed on a VF or LCD using a standard image quality standard (hereinafter referred to as SD) signal. That is the case.

  Further, in the entire camera system, the periphery of the down converter is often processed by a luminance signal or a color difference signal instead of an RGB signal. In the VF or LCD of the conventional device described in Patent Document 1, the RGB signal for obtaining the focus adjustment signal is processed in the subsequent stage of the entire camera system as compared with the luminance signal and the color difference signal. For this reason, in order to generate a focus adjustment signal, an RGB conversion circuit is further required in the subsequent stage of the entire camera system, and system processing becomes redundant.

  Further, the high frequency component of the luminance signal necessary for generating the focus adjustment signal corresponds to the edge portion of the image. When the occupied area ratio of the edge portion to the image is low, the down-converted focus adjustment signal may lose the high-frequency component information itself. Therefore, when the edge portion of the image is not processed at all, accurate focus adjustment cannot be performed.

  Further, it is necessary to separate the high frequency component of the luminance signal in order to generate the focus adjustment signal. However, when high-frequency components are separated at a predetermined threshold, the ratio between the low-frequency components and the high-frequency components changes according to the image pattern, and a dynamic focus adjustment signal cannot be generated.

  The present invention has been made in view of the above points, and even when the resolution of the captured image signal and the image signal used for display is different, the focus adjustment is easy, the redundancy of the system processing is eliminated, and the down conversion is performed. It is an object of the present invention to provide a focus adjustment signal generation device and an imaging device that can generate a focus adjustment signal dynamically without losing information on an edge portion of an image and without depending on an image pattern.

In order to solve the above-mentioned problems, the present invention comprises means described in 1) to 4) below.
  That is,
1) Image signal generation means for imaging a subject and generating an image signal having a resolution of a first number of pixels;
  Filter means for extracting a high frequency component having a predetermined frequency or higher from a luminance signal of an image signal having a resolution of the first number of pixels;
  The extracted absolute value of the high frequency component is compared with a predetermined threshold, and if it is equal to or greater than the threshold, a first detection signal is output, and if it is smaller than the threshold, a second detection is performed. Level comparison means for outputting a signal;
  Expansion means for expanding and outputting the output period of the first detection signal output from the level comparison means to a period corresponding to a width setting signal for setting the width of the output period;
When the first detection signal output from the enlarging means is input, the first color difference signal indicating a predetermined color is selected, and when the second detection signal is input, an achromatic color is selected. Color difference signal selection means for selecting a second color difference signal;
  Adjustment signal generation means for generating a focus adjustment signal by outputting the first or second color difference signal selected by the color difference signal selection means;
  Subtracting at least one of the number of lines in the vertical direction and the number of pixels in the horizontal direction of the focus adjustment signal generated by the adjustment signal generation means, and converting the focus adjustment signal to the resolution of the first number of pixels. Down-converting means for down-converting to a second resolution lower in resolution than the image signal of
  Display means for displaying a focus adjustment signal having a second resolution lower than the down-converted image signal having the resolution of the first number of pixels;
  With
  When the second detection signal is input to the display means, an achromatic focus adjustment signal is displayed, and when the first detection signal that is an edge portion of the subject is input, a predetermined value is displayed. An image pickup apparatus characterized in that the color is displayed for display.
2) storage means for storing the first or second detection signal as an output signal of N bits (N is an integer of 2 or more);
  AND operation means for calculating a logical product of the N-bit output signal and the width setting signal to obtain an output signal of a set bit among the N-bit output signal;
  OR operation means for calculating the logical sum of the N-bit output signals and extending the output period of the first detection signal;
  The imaging apparatus according to claim 1, comprising the magnifying means.
3) Luminance signal peak value detecting means for detecting a peak value of the luminance signal in one screen;
  A luminance signal average value calculating means for calculating an average value of the luminance signals in the one screen;
  An arithmetic means for calculating the peak value and the average value by a predetermined arithmetic expression to obtain the threshold value;
  The imaging apparatus according to claim 1, further comprising:
4) The imaging apparatus according to claim 3, further comprising an iris adjusting unit that limits a light amount of incident light from the subject based on the peak value supplied from the luminance signal peak detecting unit.

  According to the present invention, it is possible to generate a focus adjustment signal using a high-resolution HD signal based on a luminance signal. Therefore, an accurate focus adjustment signal is generated without losing the high frequency component of the HD signal.

  In addition, according to the present invention, since the luminance signal and the color difference signal are used, it is not necessary to provide an RGB conversion circuit for generating a focus adjustment signal as in the prior art. Therefore, the circuit scale can be reduced as compared with the conventional circuit, and the redundancy of system processing is eliminated.

  Further, according to the present invention, whether or not a high frequency component is detected in a plurality of pixels even when a high frequency component is detected in a very short time, for example, in the case of only one pixel in an edge portion of an image. To be expanded. Therefore, the focus can be adjusted accurately even when down-converted.

  Further, according to the present invention, the threshold value can be variably set according to the pattern of the image, and the high frequency component in the predetermined direction of the luminance signal corresponding to the pattern can be detected. Therefore, accurate dynamic focus adjustment can be performed regardless of the pattern.

<First Embodiment>
Hereinafter, a first embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing an imaging apparatus according to an embodiment of the present invention. In the figure, a CCD (Charge Coupled Device) 11 is used as an example of an imaging device. The CCD 11 photoelectrically converts incident light from a subject to generate a high-resolution HD signal, and supplies the HD signal to the camera signal processing unit 12. The camera signal processing unit 12 generates a luminance signal Y and two kinds of color difference signals (R−Y) and (R−B) image signals from the HD signal, and these signals are branched into two. One is supplied to the recording system 19 and the other is supplied to the focus processing unit 13.

 In the focus processing unit 13, the luminance signal Y and two kinds of color difference signals (R−Y) and (B−Y) that have been subjected to predetermined processing are supplied to the down converter 14. The down converter 14 converts the luminance signal Y and the two types of color difference signals (R−Y) and (B−Y) into the SD signal band Y ′ and the two types of color difference signals (R−Y) ′ (B−Y) ′. Downconvert. Down-conversion is to reduce at least one of the number of vertical lines and the number of horizontal pixels of each signal. The luminance signal Y ′ and the two types of color difference signals (R−Y) ′ and (B−Y) ′ are respectively supplied to the color encoder 15 and the RGB matrix processing unit 16. The color encoder 15 encodes the luminance signal and the color signal based on the input luminance signal Y ′ and the two kinds of color difference signals (R−Y) ′ and (B−Y) ′. These luminance signals and color signals are output from the S terminal 17.

  Further, the RGB matrix processing unit 16 uses a predetermined matrix calculation formula based on the input luminance signal Y ′ and the two types of color difference signals (RY) ′ and (BY) ′ to generate an R signal and a G signal. And B signal. These RGB signals (three primary color signals) are supplied to the VF / LCD display system 18. The VF / LCD display system displays an image based on the RGB signals. The circuit units from the camera signal processing unit 12 to the color encoder 15 and the RGB matrix processing unit 16 constitute a camera processing LSI (Large Scale Semiconductor Integrated Circuit) 50.

  Next, a focus processing unit (focus adjustment signal device) which is a main part of the present embodiment will be described in detail. In the present embodiment, for the purpose of generating a focus adjustment signal with higher performance, a focus adjustment signal is generated using an HD signal so that the high frequency component of the luminance signal is not lost by down-conversion. As shown in FIG. 1, the focus processing unit 13 is positioned in front of the down converter 14 in the entire camera system, and has a configuration shown in the block diagram of FIG.

  FIG. 2 is a block diagram illustrating a specific configuration example of the focus processing unit 13. In the figure, the focus processing unit 13 is composed of a high frequency component processing device 22 and switch circuits 23 and 24. Each setting signal b (b1 to b4) from a microcomputer (hereinafter referred to as a microcomputer) 21 is supplied to the high frequency component processing device 22. Then, the high-frequency component processing device 22 performs predetermined processing, which will be described later, on the input luminance signal Y based on the setting signals b (b1 to b4), and outputs color difference signals (CB_AF) and (CR_AF). To do.

The signals selected in the switch circuits 23 and 24 are switched by an on / off control signal a from the microcomputer. The switch circuits 23 and 24 select one of the color difference signals (CB_AF) and (CR_AF) from the high frequency component processing device 22 and the color difference signals (RY) and (BY) from the camera signal processing unit 12. And output. When the user needs focus adjustment, an on / off control signal a is output from the operation unit 20 and supplied to the switch circuits 23 and 24 through the microcomputer 21. The switch circuits 23 and 24 select the color difference signals (CB_AF) and (CR_AF) on the high frequency component processing device 22 side according to the on / off control signal a, and the color difference signals (RY) and (BY), respectively. Output as.

  FIG. 3 is a block diagram showing a specific configuration example of the high frequency component processing apparatus 22 shown in FIG. In the high-frequency component processing device 22 shown in the figure, the luminance signal Y from the camera signal processing unit 12 is supplied to a high-pass filter (HPF) 31. The HPF 31 extracts a high frequency component in the horizontal direction of the luminance signal Y having a predetermined frequency or higher. The direction in the present embodiment is the horizontal direction, but it may be the vertical direction. The extracted high frequency component is supplied to an absolute value processing circuit (ABS) 32. The ABS 32 calculates the absolute value of the high frequency component. The absolute value of the high frequency component is supplied to the level comparison unit 33.

The level comparison unit 33 compares the absolute value of the high frequency component with a preset threshold (EDG_TH), separates the high frequency component, and outputs a detection signal ds. The threshold value (EDG_TH) is supplied by the TH setting signal b1. When the absolute value of the high frequency component is equal to or greater than the threshold value (EDG_TH), the detection signal ds having the high level value H is output, and in other cases, the detection signal ds having the low level value L is output. This detection signal ds is processed by an enlargement unit 34 described later and output as a detection signal ds ′. This detection signal ds' is supplied to the switch circuits 35 and 36, respectively.

 The switch circuits 35 and 36 are commonly supplied with an achromatic zero set value (Zero) as a zero signal c to one terminal. A PB setting value (EDG_PB) and a PR setting value (EDG_PR) are supplied to the other terminals by the PB setting signal b3 and the PR setting signal b4. The PB set value (EDG_PB) and the PR set value (EDG_PR) are values set in advance for coloring a predetermined color on the image. An input signal at one of the terminals is selected based on the detection signal ds ′ from the enlargement unit 34. Here, the switch circuits 35 and 36 select the PB set value (EDG_PB) and the PR set value (EDG_PR) during the period in which the detection signal ds ′ having the high level value H is input by the enlargement unit 34. During the period when the low level value L is input, the zero setting value (Zero) is selected.

  When focus adjustment is not performed, the focus processing unit 13 operates as follows. The switch circuits 23 and 24 output the color difference signals (R−Y) and (B−Y) output from the camera signal processing unit 12 as they are through through the on / off control signal a supplied from the microcomputer 21. That is, the color difference signals (R−Y) and (B−Y) that are not processed at all are used as the output color difference signals of the focus processing unit 13.

  When performing focus adjustment, the focus processing unit 13 operates as follows. When the absolute value of the high frequency component is equal to or greater than the threshold value (EDG_TH), the setting values (EDG_PB) and (EDG_PR) for coloring a predetermined color on the image are selected. Then, the switch circuits 35 and 36 supply the color difference signals (CB_AF) and (CR_AF) having the set values (EDG_PB) and (EDG_PR) to the switch circuits 23 and 24, respectively. The switch circuits 23 and 24 replace the color difference signals (CB_AF) and (CR_AF) with the color difference signals (RY) and (BY) and output them. As described above, the focus adjustment signal is obtained from the high frequency component in the horizontal direction of the luminance signal Y. The luminance signal in the HD signal band and the focus adjustment signal are down-converted by the down converter 14 and an image in which a predetermined color is colored on the monochrome signal in the SD signal band is displayed on the VF / LCD display system 18. .

  Note that the state in which the focus adjustment is in effect is a state in which the horizontal high-frequency component of the luminance signal Y that is equal to or greater than the threshold value (EDG_TH) is obtained most. This state is a state in which the occupied area ratio of the edge portion with respect to one screen is the largest. The focus can be adjusted by turning a focus ring (not shown).

 Here, consider a case where the level comparison unit 33 detects only one pixel as a high frequency component in the horizontal direction of the luminance signal Y. In this case, the down converter 14 may convert the HD signal band into the SD signal band, and the high frequency component information itself may be lost. When the high frequency component information itself is lost, the VF / LCD display system 18 has the same result as when the focus is shifted, and the focus cannot be adjusted accurately.

  Therefore, as shown in FIG. 3, even when a high-frequency component of only one pixel is detected, the high-frequency component processing device 22 does not lose information on the high-frequency component by the down-conversion process described above. An enlarged portion 34 is provided.

  For example, the enlargement unit 34 has the configuration shown in the block diagram of FIG. A 1-bit detection signal ds having a high level value H or a low level value L is sequentially input to the enlargement unit 34 as a comparison result (edge_comp) in the level comparison unit 33. In addition, the number of times that the detection signal ds having the high level value H is continuously output is determined by the preset width setting value (MSK_HABA). The width setting value (MSK_HABA) is supplied to the enlargement unit 34 by the width setting signal b2.

  The N-bit shift register 41 accumulates the comparison result (edge_comp) supplied from the level comparison unit 33 of FIG. In order to enlarge one pixel or more, N needs to be an integer of 2 or more. The AND circuit group 42 calculates a logical product of the N-bit output signal from the shift register 41 and the width setting signal b 2 supplied from the comparator 44. As a result, only the set bits of N bits are obtained. Thereafter, the N-input OR circuit 43 calculates a logical sum of N bits, expands the width of the set period, and outputs a detection signal ds ′.

 FIG. 5 shows a circuit diagram of an example of the enlargement unit 34. In this figure, the same components as those in FIG. 5 includes an N-bit shift register 41, an AND circuit group 42 having N 2-input AND circuits, an N-input OR circuit 43, and a comparator group 44 having N comparators. ing. Here, N = 15 is illustrated as an example.

  Each of the 15 comparators (com0 to 14) constituting the comparator group 44 compares the preset CO setting value (hx) with the width setting value (MSK_HABA) of the width setting signal b2 supplied by the microcomputer 21. . As shown in FIG. 5, when N = 15, the subscript x of the CO setting value (hx) is 0 to 7, and the CO setting value (hx) is h0 = 0, h1 = 1,. Has the value of The CO set value (h0) is input to the comparator (com7), the CO set value (h1) is input to the comparators (com6, com8), and the CO set value (h2) is input to the comparators (com5, com9). Thereafter, the CO set values (h3 to h6) are also input in the same correspondence relationship, and the CO set values (h7) are input to (com0, com14). Here, MSK_HABA = 1. When MSK_HABA = 1, in the comparison result (edge_comp), the width of the period having the high level value H is expanded by one period before and after and is supplied to the switch circuits 35 and 36 as the detection signal ds ′. That is, the pixels having the high level value H are expanded by one pixel on both sides. Similarly, if MSK_HABA = 2, the pixels having the high level value H can be expanded by two pixels on the left and right, and the width setting value (MSK_HABA) can be changed by the setting of the microcomputer 21.

  Each comparator (com0 to 14) outputs a width setting signal b2 having MSK_HABA = 1 when MSK_HABA ≧ hx. In other cases, MSK_HABA = 0 and the width setting signal b2 is output. Therefore, the width setting signal b2 output from the comparators (com6 to 8) has MSK_HABA = 1, and the width setting signals b2 output from the other comparators (com0 to 5, com9 to 14) have MSK_HABA = 0. Have.

  The 15 two-input AND circuits (and 0 to 14) constituting the AND circuit group 42 calculate the logical product of the input width setting value (MSK_HABA) and the signal stored in the shift register 44. That is, when the width setting signal b2 having MSK_HABA = 1 is input, the detection signal accumulated in the shift register 41 is output. On the other hand, when the width setting signal b2 having MSK_HABA = 0 is input, all the signals having the low level value L are output. Therefore, when the detection signal ds has a high level value H, a signal having a high level value H is output from the three two-input AND circuits (and 6 to 8). The other 12 2-input AND circuits (and0 to 5, and 9 to 14) always output a signal giving a low level.

  FIG. 6 is a diagram illustrating an example of the timing charts of FIGS. 4 and 5. FIG. 6A shows an output result when only one pixel has a high level value H in the comparison result (edge_comp) of the detection signal ds. A 1-bit comparison result (edge_comp) is supplied from the level comparison unit 33 and input to the shift register 41. FIG. 6B shows an output signal of the 15-bit output terminal of the shift register 41. The comparison result (edge_comp) is delayed by one period and stored in each shift register. FIG. 6C shows a 15-bit output signal of the AND circuit group 42. As described above, the width setting signal b2 is supplied to the AND circuit group 42, and the third bit of the seventh, eighth and ninth bits of the shift register 41 supplied to the AND circuit (and7 to 9) is high. It is output as a signal having a level value H. FIG. 6D shows an output signal of the N-input OR circuit (N = 15) 43. The N-input OR circuit (N = 15) 43 adds the 15-bit signal output from the AND circuit group 42. The width of the period during which the high level value H is supplied is expanded from one period to three periods centering around the place delayed by eight periods. Then, the N-input OR circuit (N = 15) 43 sequentially supplies the detection signal ds ′ having the high level value H or the low level value L to the switch circuits 35 and 36 with a delay of 8 periods. As described above, even when a high-frequency component is detected with only one pixel, enlargement is performed as if the high-frequency component was detected with three pixels.

  FIG. 7 is a diagram showing another example of the timing charts of FIGS. 4 and 5. FIG. 7A shows an output result when two adjacent pixels have a high level value H in the comparison result (edge_comp). FIG. 7B shows an output signal of the 15-bit output terminal of the shift register 41. FIG. 7C shows a 15-bit output signal of the AND circuit group 42. FIG. 7D shows an output signal of the N-input OR circuit (N = 15) 43. As in the case where only one pixel in FIG. 6 has the high level value H, the width of the period during which the high level value H is supplied ranges from two periods to four periods, centering on the place delayed by eight periods. Expanded to minutes. Then, a detection signal ds' having a high level value H or a low level value L is sequentially supplied to the switch circuits 35 and 36 with a delay of 8 periods. As described above, when a high frequency component is detected in two adjacent pixels, enlargement is performed as if the high frequency component was detected in four pixels.

  Accordingly, the enlargement unit 34 enlarges the pixels in the edge portion according to the set width setting value (MSK_HABA), and outputs the result as if the high frequency components of the luminance signals of the plurality of pixels were detected. For this reason, even if the down-converting process is performed by the down-converter 14 located downstream from the enlargement unit 34, the result of the detected high-frequency component is not lost.

  According to the first embodiment, the focus adjustment signal of the luminance signal Y and the two types of color difference signals (RY, BY) is subjected to predetermined focus processing in the HD signal band in the focus processing unit 13. The downconverter 14 downconverts the signal to an SD signal. After down-conversion, the RGB matrix processing unit 16 converts the signals into R, G, and B signals according to a predetermined matrix arithmetic expression and supplies the converted signals to the VF / LCD display system 18. The VF / LCD display system displays an image based on the RGB signals. The displayed image of the subject is a monochrome image in the SD signal band, and a focus adjustment image with a predetermined color is displayed on the edge portion.

  Therefore, the user can perform the focus adjustment based on the focus adjustment signal using the HD signal without losing the high frequency component. Further, since an RGB conversion circuit for the focus adjustment signal generation device is not required, the circuit scale is small and system processing is not redundant. Even when the occupied area ratio of the edge portion with respect to one screen is low, the information of the down-converted high-frequency component itself is not lost by providing the enlargement unit 34, so that the focus adjustment can be performed accurately.

<Second Embodiment>
A second embodiment of the imaging apparatus of the present invention will be described. FIG. 8 is a block diagram showing an imaging apparatus according to another embodiment of the present invention. In the figure, the same components as those in FIG. In FIG. 8, the amount of incident light from a subject (not shown) is limited by the iris mechanism 61. The aperture value of the iris mechanism 61 is controlled by the microcomputer 21. After the amount of light is limited, the CCD 11 photoelectrically converts incident light from the subject to generate a high-resolution HD signal. The HD signal is supplied to the camera signal processing unit 12 in the camera processing LSI 50.

  The image processing unit 53 is obtained by integrating the down converter 14, the color encoder 15, and the RGB matrix processing unit 16 of FIG. 1. An image processing unit 53, a camera signal processing unit 12, a focus processing unit 13, a luminance signal peak detection unit 51 and a luminance signal block calculation unit 52 (not shown in FIG. 1) are connected to a camera processing LSI (large-scale semiconductor integrated circuit) 50. It is composed. Here, the luminance signal peak detection unit 51 and the luminance signal block calculation unit 52 are used for automatic exposure (AE). The luminance signal peak detection unit 51 and the luminance signal block calculation unit 52 are given a necessary initial setting by the setting signal d from the microcomputer 21 and receive AE data. Further, the microcomputer 21 controls opening and closing of the iris mechanism 61 for automatic exposure.

  The high-frequency component processing device 22 in the focus processing unit 13 shown in FIGS. 2 and 3 has various settings such as a TH setting signal b1 having a threshold value (EDG_TH) and a width setting signal b2 having a width setting value (MSK_HABA). Signal b is supplied. These set values are determined by the microcomputer 21. In this embodiment, in order to reduce the influence of the detection accuracy due to the pattern, the threshold (EDG_TH) is determined by calculation using data originally taken into the microcomputer 21 for AE.

  Next, the control operation by the microcomputer 21 will be described with reference to the flowchart of FIG. First, when processing is started (step S1), the microcomputer 21 reads the peak value (PEAK) of the luminance signal from the luminance signal peak detector 51 (step S2). The peak value (PEAK) of the luminance signal is the maximum value of the luminance signal in one screen.

  Next, the microcomputer 21 reads the luminance signal block calculation value YB [m] [n] from the luminance signal block calculation unit 52 (step S3). One screen is divided into m blocks (m is a natural number of 2 or more) in the horizontal direction and n blocks (n is a natural number of 2 or more) in the vertical direction. The average value of the luminance signal in each of the divided (m × n) blocks is the luminance signal block calculation value YB [m] [n]. The luminance signal block calculation value YB [m] [n] is a value originally obtained for AE.

Next, the microcomputer 21 calculates the average value (AVE) of the luminance signals of one screen using the luminance signal block calculation value YB [m] [n] read in step S3 (step S4). The average value (AVE) of the luminance signal of one screen is calculated by the following equation (1).
AVE = ΣYB [m] [n] / (m × n) (1)
Here, ΣYB [m] [n] represents the total sum of the luminance signal block calculation values YB [m] [n].

Next, the microcomputer 21 calculates the following equation (2) from the peak value (PEAK) of the luminance signal read in step S2 and the average value (AVE) of the luminance signal of one screen calculated in step S4.
EDG_TH = (PEAK-AVE) / 8 (2)
A threshold value (EDG_TH) is calculated from the equation (2) (step S5). Here, the value “8” of the denominator on the right side in the equation (2) is a value obtained by experiments. However, the value of the denominator can be dynamically variably set according to the pattern of the image so as to reduce the influence of the detection accuracy due to the pattern.

  Finally, the microcomputer 21 outputs the TH setting signal b1 having the threshold (EDG_TH) calculated as described above to the level comparison unit 33 (step S6), and ends the process (step S7).

  According to the second embodiment, the threshold value (EDG_TH) is variable according to the pattern of the image. For this reason, the level comparison unit 33 in the focus processing unit 13 can detect a high-frequency component in the horizontal direction of a dynamic luminance signal corresponding to a picture.

  In addition, this invention is not limited to the above embodiment. For example, although it has been described that the HD signal is down-converted to the SD signal, the present invention can also be applied when the resolution of the captured image signal is different from the resolution of the VF or LCD that displays the image signal. Further, although the threshold value is calculated from the peak value and the average value of the luminance signal, the threshold value may be calculated only from the average value. Further, although the peak value and average value of the luminance signal are calculated from one screen, they may be calculated by integration from an image captured for a predetermined time.

It is a block diagram of the imaging device of the present invention. FIG. 2 is a block diagram of a focus processing unit in FIG. 1. It is a block diagram of the high frequency component processing apparatus in FIG. It is a block diagram of the expansion part in FIG. FIG. 4 is a circuit diagram of an enlarged portion in FIG. 3. 6 is a timing chart for explaining the operation of FIG. 5. 6 is another timing chart for explaining the operation of FIG. 5. It is another block diagram of the imaging device of this invention. It is a flowchart for operation | movement description of FIG.

Explanation of symbols

11 CCD
12 Camera Signal Processing Unit 13 Focus Processing Unit 14 Down Converter 18 VF / LCD Display System 21 Microcomputer
22 High-frequency component processing device 23, 24, 35, 36 Switch circuit 31 High-pass filter (HPF)
32 absolute value processing (ABS) circuit 33 level comparison unit 34 enlargement unit 41 shift register 42 AND circuit group 43 N-input OR circuit 51 luminance signal peak detection unit 52 luminance signal block calculation unit 53 image processing unit 61 iris mechanism

Claims (4)

Image signal generating means for imaging a subject and generating an image signal having a resolution of a first number of pixels ;
Filter means for extracting a high frequency component having a predetermined frequency or higher from a luminance signal of an image signal having a resolution of the first number of pixels ;
The extracted absolute value of the high frequency component is compared with a predetermined threshold, and if it is equal to or greater than the threshold, a first detection signal is output, and if it is smaller than the threshold, a second detection is performed. Level comparison means for outputting a signal;
Expansion means for expanding and outputting the output period of the first detection signal output from the level comparison means to a period corresponding to a width setting signal for setting the width of the output period;
When the first detection signal output from the enlarging means is input, the first color difference signal indicating a predetermined color is selected, and when the second detection signal is input, an achromatic color is selected. Color difference signal selection means for selecting a second color difference signal;
Adjustment signal generation means for generating a focus adjustment signal by outputting the first or second color difference signal selected by the color difference signal selection means;
Subtracting at least one of the number of lines in the vertical direction and the number of pixels in the horizontal direction of the focus adjustment signal generated by the adjustment signal generation means, and converting the focus adjustment signal to the resolution of the first number of pixels. Down-converting means for down-converting to a second resolution lower in resolution than the image signal of
Display means for displaying a focus adjustment signal having a second resolution lower than the down-converted image signal having the resolution of the first number of pixels ;
Bei to give a,
When the second detection signal is input to the display means, an achromatic focus adjustment signal is displayed, and when the first detection signal that is an edge portion of the subject is input, a predetermined value is displayed. An image pickup apparatus characterized in that the color is displayed for display . Storage means for storing the first or second detection signal as an output signal of N bits (N is an integer of 2 or more);
AND operation means for calculating a logical product of the N-bit output signal and the width setting signal to obtain an output signal of a set bit among the N-bit output signal;
OR operation means for calculating the logical sum of the N-bit output signals and extending the output period of the first detection signal;
Imaging device according to claim 1, wherein the configuring the expansion means comprises a. Luminance signal peak value detecting means for detecting a peak value of the luminance signal in one screen;
A luminance signal average value calculating means for calculating an average value of the luminance signals in the one screen;
An arithmetic means for calculating the peak value and the average value by a predetermined arithmetic expression to obtain the threshold value;
The imaging apparatus according to claim 1, further comprising: The imaging apparatus according to claim 3 , further comprising an iris adjustment unit configured to limit an amount of incident light from the subject based on the peak value supplied from the luminance signal peak detection unit.

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