JP2003230155A - Apparatus and circuit for processing image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit and an apparatus for processing an image in which a color component suppressing process and a focusing process can be performed with a simpler constitution. <P>SOLUTION: A digital camera 1 interpolates an image signal of each pixel input from a Bayer type CCD (imaging element) by using an image signal of a close pixel, and generates image signals of three primaries of the respective pixels. The image signals of the three primaries are transformed into a luminance signal Y and color difference signals Cr, Cb. A line extracting circuit 77 extracts line components from the signal Y by using a line extracting filter 76a and an absolute value adding circuit 76b. For the pixel decided as the line component, color difference signals Cr, Cb are suppressed by multiplying a gain in response to detection levels of the pixel decided to be the line component by the pixels by using multipliers 82, 83. A focus evaluate value is calculated based on a signal from the circuit 77 (line extracting filter 76a), and a focus control is performed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing circuit and an image processing apparatus, and more particularly to an image processing circuit and an image processing apparatus that are accompanied by color component suppression processing (for example, color difference suppression processing) and focus processing.

[0002]

2. Description of the Related Art In an image processing device such as a digital camera, a color difference suppression process (color component suppression process) is performed based on an output after passing through a Sobel filter (line segment extraction filter) for the purpose of suppressing occurrence of false colors. There are those equipped with an image processing circuit for performing (1).

On the other hand, in such an image processing apparatus (or image processing circuit), a focus evaluation value calculation filter for calculating a focus evaluation value is provided in a separate circuit in order to further perform an autofocus operation (automatic focusing operation). Is provided as. As such a focus evaluation value calculation filter, there is, for example, one that calculates a value based on contrast as a focus evaluation value.

[0004]

However, in the image processing circuit in such an image processing apparatus, as described above, the Sobel filter and the focus evaluation value calculation filter are provided separately. Therefore, there is a problem that the image processing circuit becomes complicated and the loss is large.

Therefore, in view of the above problems, it is an object of the present invention to provide an image processing circuit and an image processing apparatus which can perform color component suppression processing and focus processing with a simpler configuration.

[0006]

In order to achieve the above object, the invention of claim 1 is an image processing apparatus for performing a predetermined image processing on an image signal input from an image pickup element, wherein the image pickup element is 3 Of the primary color components, three types of photoelectric conversion elements that respectively output image signals of the primary color components are arranged in accordance with a predetermined arrangement rule for each pixel,
Interpolation means for performing interpolation processing on the image signal of each pixel input from the image pickup device by using image signals of neighboring pixels, and outputting an image signal of three primary color components for each pixel;
Color space conversion means for converting an image signal of a color space having a primary color component into an image signal of a color space having a luminance component and a color component, and a line segment extraction circuit for extracting a line segment component from the signal value of the luminance component. And a calculation unit that calculates a focus evaluation value based on the signal from the line segment extraction circuit and a suppression unit that suppresses the signal value of the color component for the pixel determined to be the line segment component by the line segment extraction circuit. Means and are provided.

According to a second aspect of the invention, in the image processing apparatus according to the first aspect of the invention, the calculating means integrates the output from the line segment extraction circuit for a plurality of pixels within a predetermined focus area. The focus evaluation value is calculated.

According to a third aspect of the present invention, in the image processing apparatus according to the first aspect of the present invention, the suppressing means determines the signal value of the color component of the pixel according to the magnitude of the output from the line segment extracting circuit. It is characterized by changing the degree of suppression of.

According to a fourth aspect of the present invention, in the image processing apparatus according to the first aspect of the present invention, the line segment extraction circuit suppresses the signal value of the color component as a line segment extraction filter for extracting a line segment component. It is characterized in that it is possible to switch between the first filter used when determining whether or not to decide whether or not to use and the second filter used when calculating the focus evaluation value.

According to a fifth aspect of the present invention, three types of photoelectric conversion elements for outputting image signals of any one of the three primary color components are input from an image pickup element arranged for each pixel according to a predetermined arrangement rule. An image processing circuit for performing a predetermined image processing on an image signal, wherein the image signal of each pixel input from the image pickup device is interpolated using the image signals of neighboring pixels, and each pixel has three primary color components. Means for outputting an image signal of a color space, a color space converting means for converting an image signal of a color space having three primary color components into an image signal of a color space having a luminance component and a color component, and a signal value of the luminance component. A line segment extraction circuit that extracts a line segment component from the line segment extraction circuit, and a pixel that is determined to be a line segment component by the line segment extraction circuit, a suppression unit that suppresses the signal value of the color component, and a line segment extraction circuit Based on signal Characterized in that it comprises calculating means for calculating a focus evaluation value, the Te.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<1. Schematic structure of digital camera> Fig. 1
FIG. 1 is a front view showing an appearance of a digital camera (more specifically, a digital still camera) 1 as an image processing apparatus according to this embodiment. 2 is a schematic diagram showing an internal configuration of the digital camera 1, and FIG. 3 is a digital camera 1.
FIG. 3 is a schematic diagram showing the configuration of an image processing circuit 20 provided in the interior of FIG.

As shown in FIG. 1, the digital camera 1
It is composed of a box-shaped camera body portion 32 and a rectangular parallelepiped image pickup portion 33. A zoom lens 34, which is an imaging lens, and a finder 35 are provided on the front side of the imaging unit 33.

One end of the camera body 32 is a grip portion 3
6 and the built-in flash 37 in the upper center of the front side
Is provided, and a shutter button 38 is provided on the upper surface side. Here, the shutter button 38 is in a half-pressed state S1 and a fully-pressed state S2 as used in a silver halide camera.
It is a two-step switch that can detect and.

Although not shown, the camera body 3
A liquid crystal display (LCD) for displaying a captured image on the monitor and reproducing the recorded image on the rear side of the display device 2.
Is provided. In addition, a power switch, various operation buttons, and the like are provided on the back side of the camera body 32.

Next, with reference to FIG. 2, an outline of the internal configuration of the digital camera 1 will be described.

The light passing through the lens 34 and collected on the CCD 11 is converted into an electric signal by photoelectric conversion in the CCD 11.

The CCD 11 is a single plate type CCD provided with a color filter array. A large number of photodiodes that control photoelectric conversion are two-dimensionally arranged in a matrix in the CCD 11 to correspond to each pixel, and each pixel is covered with one of the color filters of the primary color components (R, G, B). It is being appreciated. Here, as shown in FIG. 4, it is assumed that the CCD 11 is equipped with a Bayer type color filter array. In this Bayer CCD, G filters that contribute to the luminance signal are arranged in a checkered pattern, and R and B filters are further arranged in a checkered pattern in the remaining portion. In this way, each pixel has R, G, B
Charges corresponding to any of the primary color components are accumulated. The charges accumulated in the CCD 11 are sequentially taken out line by line and output as a one-dimensional electric signal.

As the Bayer type CCD, there are several types such as a type in which Gs are vertically arranged in addition to the type shown in FIG. Further, the present invention is not limited to the Bayer CCD, but can be applied to various CCDs.

CDS (correlated double sampling) circuit 12
And AGC (auto gain control) circuit 13
Predetermined analog signal processing is performed on the electric signal (image signal) output from the CCD 11. Specifically, CD
The S circuit 12 reduces the noise of the electric signal,
The C circuit 13 adjusts the level of the electric signal by adjusting the gain.

Thereafter, the A / D converter 14 converts the electric signal (analog signal) for each pixel into a 12-bit digital signal.

Next, the image signal as the digital signal is input to the image processing circuit. This image processing circuit 20
Internal processing will be described later. After that, the image signal subjected to the predetermined processing is stored as image data in the image memory 9 as a buffer.

The image data stored in the image memory 9 is
The image data is read out to the image compression circuit 41, and a predetermined compression format (JPE
G, etc.) and is written back to the image memory 9 again. Further, thereafter, this image data is read from the image memory 9, transferred to the memory card 90, and written in the memory card 90 under the drive control of the memory card driver 42. In addition, these operations are generally controlled by the CPU 10.

In this way, when the shutter button 38 is pressed down to the fully-pressed state S2, the recording operation of the photographed image is performed.

Further, in this digital camera 1,
The autofocus operation is performed prior to recording the subject image.

Specifically, when the shutter button 38 is in the half-pressed state S1, this autofocus (AF) operation is started. When the shutter button 38 is pressed halfway in a state in which photography is possible, the AF motor drive circuit drives the AF motor 52 under the control of the camera controller 50. At this time, an output after passing through a Sobel filter (line segment extraction filter) described later is used as an evaluation value at the time of focusing to realize an optimum focused state.

Further, the digital camera 1 has various operation switch groups 55 in addition to the above-mentioned shutter button 38, and can perform various setting operations.

The outline of the digital camera 1 has been described above. Next, the color difference suppression process (color component suppression process) and the focus evaluation value calculation process in the image processing circuit 20 will be described in detail.

<2. Color Difference Suppression Processing><2-1 Bayer CCD and Interpolation Processing> The description will proceed with reference to FIG.

12 in the A / D conversion circuit 14 (FIG. 2)
The image signal converted into the bit digital electric signal is W
It is input to the B (white balance) circuit 2, and white balance is adjusted by RGB level conversion.

After the white balance is adjusted, the electric signal of each pixel is input to the interpolation circuit 3, and the interpolation process is performed for each pixel. That is, each pixel is
Since it only has information about one of the G and B primary color components, an interpolation process is performed in which information about the other primary color components is estimated based on the values of surrounding pixels.

By this interpolation processing, for each pixel,
Information of 12 bits for each of R, G, and B will be given. For example, the information of the primary color components of "G" and "R" at the position of "B" among the four pixels in the rectangular area 11a of FIG. 4 is obtained by interpolation. The information of the “G” primary color components at this position can be obtained by, for example, obtaining the average value of four G components that are adjacent in the vertical and horizontal directions. The information of the "R" primary color component at this position can be obtained by, for example, obtaining the average value of four R components that are adjacent to the upper left, the upper right, the lower left, and the lower right. The same applies to other positions.

In this way, the interpolation circuit 3 performs an interpolation process on the image signal of each pixel using the image signals of neighboring pixels, and outputs the image signals of the three primary color components for each pixel.

After the interpolation processing is performed, the electric signals (R, G, B) of each pixel are output in the linear matrix circuit 4.
After the predetermined color correction processing is performed, the color correction signal is input to the γ correction circuit 5. In the γ correction circuit 5, electric signals (R, G, B)
Is corrected by the γ correction table (RGB gamma LUT) 51 according to the reproduction characteristics of the display. Further, in the γ correction circuit 5, the 12-bit electric signal is compressed to 8 bits.

<2-2 Color Space Conversion Processing> The electrical signals (R, G, B) compressed to 8 bits are next input to the color difference matrix circuit 6. The color difference matrix circuit 6 is
The conversion matrix includes a Y matrix 61, a Cr matrix 62, and a Cb matrix 63.
The color space having the primary color components of is converted into the color space having the luminance component (Y) and the color difference components (Cr, Cb).

Formula 1 represents the Y matrix 61, the Cr matrix 62, and the Cb matrix 63 by a color difference matrix of 3 rows and 3 columns. Therefore, the RGB color space is
It can be expressed as being converted into a color space having a luminance component and a color difference component by the color difference matrix.

[0037]

[Equation 1]

<2-3 Edge Enhancement Filter Processing> The luminance component Y output from the color difference matrix circuit 6 (in the following description, an electric signal of the luminance component will be expressed as a luminance signal Y) will be described next. , Are input to the contour emphasis filter circuit 7. In the contour emphasis filter circuit 7, the luminance signal Y is branched into three. One of the branched luminance signals Y passes through the HPF 72 and one passes through the LPF 71. The other one is input to a line segment extraction circuit 77 described later.

From the luminance signal Y that has passed through the HPF 72,
A high-frequency component is detected, and the detected high-frequency component is input to and amplified by the amplifier 73, and then only the high-frequency component having a predetermined value or more is detected and output by the base clip 74.

Then, in the adder 75, the LPF 71
By adding a high frequency component of a predetermined value or more output from the base clip 74 to the brightness signal Y that has passed through, the brightness signal Y is output after the contour is emphasized.

<2-4 Line Segment Extraction Process> Of the luminance signals Y branched in the edge enhancement filter circuit 7, the remaining one is input to the line segment extraction circuit 77. In the line segment extraction circuit 77, the line segment component is extracted from the luminance signal Y by using the line segment extraction filter 76a and the like. here,
As such line segment extraction filters, Sobel filters A1 to A4 shown in FIG. 5 are exemplified.

The filter A1 is a spatial filter for detecting the boundary of a diagonal line rising to the right, the filter A2 is a spatial filter for detecting the boundary of a vertical line, and the filter A3 is
It is a spatial filter that detects the boundary of the diagonal line descending to the right,
The filter A4 is a spatial filter that detects the boundaries of horizontal lines.

Luminance signal Y input to the line segment extraction circuit 77
Are accumulated in a buffer (not shown), and the line segment extraction processing of the target pixel is performed based on the luminance signal Y accumulated in this buffer. For example, the above-described line segment extraction filters A1 to A4 are represented in a matrix form of 3 rows and 3 columns, and a line segment is formed using the luminance signal Y of the target pixel and the luminance signal Y of pixels in the vicinity of the target pixel. The extraction process will be performed. Therefore, it is necessary that at least these 9 pixel luminance signals Y are accumulated in the buffer.

Then, for the luminance signal Y of 9 pixels in 3 rows and 3 columns, pattern matching is performed with each of the line segment extraction filters A1 to A4. Then, in the case of matching, the pixel of interest (the pixel located at the center when pattern matching is performed, that is, the pixel corresponding to the second row and second column) is determined as the line segment component.

Specifically, taking the case where the line segment extraction filter A1 is applied to the pixel of interest as an example, the values of the luminance signal Y of the pixel of interest and the eight neighboring pixels are calculated by using each component of the filter A1 as a coefficient. Multiply to obtain the sum of these calculated values. Then, when the absolute value of the total value becomes larger than the predetermined value, the pixel of interest is judged by the filter A1 as a line segment component.

The calculated value (total value) represents the detection level of the line segment in the pixel of interest. That is, the larger the calculated value (total value) using the spatial filter of any of the line segment extraction filters A1 to A4, the greater the degree of detection of the line segment component in the corresponding direction. .

Here, the circuit 76b further calculates a value obtained by adding all the absolute values of the above-mentioned total values for the spatial filters of the filters A1 to A4 as a value representing the detection level of the line segment. That is, for each pixel, the sum of the absolute values of the output values from the filters A1 to A4 is calculated,
The calculated sum is used as a value representing the detection level of the line segment.

<2-5 Line Segment Chroma Killer Process> Next, based on the detection level of the line segment component detected by the line segment extraction circuit 77, both color difference components Cr and Cb (in the following description, the color difference is appropriately changed). The electrical signals of the components are converted into color difference signals Cr,
Represented as Cb. ) Is suppressed. In particular,
Based on the detection level of the line segment component, the color difference signal Cr, by referring to the line segment chromakiller setting LUT (Lookup Table) 78,
The degree of suppression of Cb is obtained, and the color difference signals Cr and Cb are suppressed by the multipliers 82 and 83 according to the degree of suppression.

At this time, the multipliers 82 and 83 perform the suppression processing based on the position information of the pixel discriminated as the line segment component and the detection level of the line segment component in each pixel according to the position information. . That is, the signal value of the color difference component is suppressed with respect to the pixel determined to be the line segment component.

FIG. 6 is a diagram showing the setting contents of the LUT 78 of the line segment chroma killer. In the figure, the horizontal axis represents the detection level of the line segment component, and the vertical axis represents the gain for the color difference signal. In other words, the suppression control is performed such that the gain for the color difference signal is reduced (in other words, higher suppression is applied to the color difference signal) for the pixel having the higher detection level of the line segment component. That is, the pixel having a higher detection level of the line segment component is suppressed more than the pixel having a lower detection level. In this way, since the degree of suppression control is changed according to the detection level of the line segment component, suppression control that does not leave unnaturalness in the output image is possible.

Further, here, when the detection level of the line segment component becomes large to some extent, the rate of decrease of the gain is made small (zero in the figure) so that the suppression degree does not become excessively large. As a result, it is possible to prevent the color from being suppressed excessively.

By the above processing, the image processing apparatus according to this embodiment outputs the luminance signal Y subjected to the edge enhancement processing and the color difference signals Cr and Cb subjected to the suppression control. . As described above, the output luminance signal Y and color difference signals Cr, Cb are recorded in the image memory 9 as a buffer, and then processed in accordance with a compression standard such as JPEG, for example, and are processed as an image file in a memory card. Etc.

As described above, in the present embodiment, such color difference suppression processing can effectively suppress the occurrence of false color.

In particular, in the above-described embodiment, since the suppression control is performed only for the pixels extracted as the line segment component, the inconvenience caused by performing the suppression control for all edge components is a problem. It can be resolved. This inconvenience is that the color is suppressed even for a fine edge (for example, a dot-like edge), and an unnatural dot-like color loss occurs. According to the present embodiment, since color suppression is applied only to the line segment, it is possible to obtain a natural depiction without fine color loss.

<3. Focus Processing> Furthermore, in the digital camera 1, auto focus processing is performed prior to recording of the subject image. This processing will be described below.

Specifically, when the shutter button 38 is pushed down to the half-pressed state S1 by the operator, this autofocus (AF) operation starts. here,
The output after passing through the Sobel filter (line segment extraction filter) described above is used as an evaluation value at the time of focusing to realize an optimum focus state.

FIG. 7 is a diagram showing a focus area E0 preset in the image P. The digital camera 1 detects the detection level of the above line segment for each pixel in the focus area E0, and moves the lens 34 by a so-called hill climbing method so that the detection level becomes maximum. In other words, the detection level of the line segment is used as the focus evaluation value.

Therefore, as shown in FIG. 3, the circuit 76b
The output value after passing through (in more detail, the output value obtained by applying the absolute value addition operation to the luminance signal Y after the Sobel filter 76a is applied) is summed up for the pixels in the focus area E0. The calculated sum total value is obtained, and the sum total value is used as the focus evaluation value.

More specifically, the area determiner 84 specifies the position of each pixel corresponding to the output value after passing through the circuit 76b, and the pixel existing at that position is determined to be the focus area E.
It is determined whether the pixel is within 0. Then, only the output values of the pixels determined to be the pixels in the focus area E0 are added (integrated) by the integrator 85. In this way, the above sum value is obtained. In other words, the area determiner 84 and the integrator 85 select the pixels located in the focus area from all the pixels, integrate the outputs from the line segment extraction circuit 77 for the selected pixels, and obtain the focus evaluation value. It has a calculation function.

FIG. 8 shows the relationship between the focus evaluation value (line segment detection level) and the lens position (that is, the focus evaluation value curve L0). As shown in FIG.
By moving the lens 34, the focus evaluation value changes. In the focused state, the line segment is captured most clearly, so the detection level of the line segment is the highest. Therefore, by moving the lens to the position corresponding to the apex of the "mountain" on the focus evaluation value curve L0, the subject in the focus area can be brought into the in-focus state.

As described above, in the digital camera 1 (or the image processing circuit 20), the focus evaluation value is calculated by the integrator 85 based on the signal from the line segment extraction circuit 77, and the focus control is performed by this focus evaluation value. It is based on the value.

According to the digital camera 1 (or the image processing circuit 20), the false color is generated by suppressing the color difference signals Cr and Cb with respect to the pixel discriminated by the line segment extraction circuit 77 as the line segment component. In addition to suppressing, it is possible to calculate the focus evaluation value based on the signal from the line segment extraction circuit 77. That is, both the color difference suppression function and the focus evaluation value calculation function are realized by sharing the line segment extraction circuit. Therefore, it is possible to calculate the focus evaluation value with a simple configuration without separately providing a contrast extraction circuit or the like for calculating the focus evaluation value.

<4. Others> In the above description, the Sobel filter is illustrated as the line segment extraction filter, but the line segment extraction filter is not limited to this. For example, a Prewitt Filter as shown in FIG. 9 may be used.
You may use the Forsen filter (ForsenFilter) shown in 0.

Further, in the above description, the Sobel filters A1 to A4 having a size of 3 × 3 are exemplified as the line segment extracting filter, but the present invention is not limited to this. For example, as shown in FIG. 11, 5 × 5 size Sobel filter B1 to
B4 may be used.

The filter B1 is a spatial filter for detecting the boundary of a diagonal line rising to the right, the filter B2 is a spatial filter for detecting the boundary of a vertical line, and the filter B3 is
It is a spatial filter that detects the boundary of the diagonal line descending to the right,
The filter B4 is a spatial filter that detects the boundaries of horizontal lines.

By using a filter of a larger size, line segment detection by the filter can be performed with higher accuracy. Therefore, by performing the color difference suppressing process with higher accuracy based on the line segment detection result, it is possible to more accurately prevent the occurrence of false colors and further improve the image quality. Further, by using such a line segment detection result, focus control can be performed more accurately.

However, when the size of the filter becomes large, there is a problem that the processing time increases as the number of calculations increases. Therefore, in order to solve this problem, the line segment extraction filters may be switched and used according to the situation.

For example, the filter size may be changed according to the total number of pixels to be filtered. More specifically, in autofocus control, line segment detection is performed using a filter having a relatively large size (for example, 5 × 5 size), while in color difference suppression processing, a relatively small size (for example, 3 ×) is used. The line segment detection may be performed using a filter (size of × 3).

In the autofocus control, as described above, the focus area for which the focus evaluation value is calculated is set. Since this focus area is usually smaller than the entire screen area, the number of pixels in the focus area has a relatively small value. Therefore, in the autofocus control, even when a filter having a relatively large size (for example, a size of 5 × 5) is used, the influence on the processing time can be suppressed to a low level. On the other hand, in the color difference suppression process, a line segment can be detected at a relatively high speed by using a filter having a relatively small size (for example, a size of 3 × 3). This makes it possible to prevent the processing speed from decreasing while accurately performing the autofocus control and the color difference suppression processing.

As described above, the line segment extraction circuit 77 switches between the line segment extraction filter used when determining whether or not to suppress the color difference signal value and the line segment extraction filter used when calculating the focus evaluation value. You may do it.

This switching operation may be performed according to the state of the shutter button 38. Specifically, shutter button 3
When 8 is in the half-pressed state S1, the line segment extraction circuit 77 functions as a line segment extraction filter and has a relatively large size (for example, 5 ×).
Line size using a filter of size 5)
U10 and 50 should just perform autofocus control based on the detection result. On the other hand, when the shutter button 38 is in the fully pressed state S2, the line segment extraction circuit 77 performs line segment detection using a filter having a relatively small size (for example, 3 × 3 size) as a line segment extraction filter,
The LUT 78, the multipliers 82, 83 and the like may perform the color difference suppression process based on the detection result and perform the image recording operation.

As can be seen by comparing FIGS. 5 and 11, line segment extraction filters A1 to A4 used in both processes.
The line extraction filters B1 to B4 have different sizes, but have common parts. For example, the filter A1 is included in the central portion of the filter B1. Therefore, it is possible to further share the circuit.

Further, in the above, the case where a single focus area is set has been exemplified, but a plurality of focus areas may be set.

FIG. 12 shows a plurality (here, three) of focus areas E1, E set in advance in the image P.
It is a figure which shows 2 and E3. The digital camera 1 determines any one of these focus areas E1, E2, E3 as a target area used for lens position determination,
The focus operation is controlled using the focus evaluation value in the target area. Specifically, the line segment extraction circuit 77
These three focus areas E based on the output from
Among the focus evaluation value curves of 1, E2 and E3, the focus area having the highest peak height of the mountain is determined as the area (target area) to be adopted as the target of the focus operation. Then, the lens 34 is moved to the position corresponding to the apex of the focus evaluation value curve for the target area. According to this, since the target area can be selected from a plurality of focus areas,
More appropriate focus control can be performed.

Alternatively, in the above, the case where the focus area is assigned to a part of the screen P is illustrated, but the focus area may be assigned to the entire screen. Specifically, as shown in FIG. 13, the entire area of the screen P is divided into a plurality of areas. FIG.
In, the total area is 3 in the vertical direction, 5 in the horizontal direction,
The case where the image is divided into a total of 15 divided areas is shown. Then, the plurality of divided areas Eij (E11 to E11
Each of E15, E21 to E25, E31 to E35) may be set as a focus area, and the target area used for lens position determination may be determined from the plurality of focus areas in the same manner as described above. According to this, it becomes possible to evaluate not only a part of the screen but the entire screen to perform focus control.

Further, in the above embodiment, the case where the color difference signal is suppressed as the signal (color signal) representing the color component is illustrated, but the invention is not limited to this. For example, the suppression processing may be performed on a color signal other than the color difference signal (for example, a signal representing only saturation) using the same idea as above.

Further, although the case where the present invention is applied to a digital still camera has been shown above, the present invention is not limited to this, and an image signal is input from a CCD provided with a color filter array such as a Bayer system such as digital video. It is possible to apply to any device that does.

The specific embodiment described above includes an invention having the following configuration.

(1) In the image processing apparatus according to the first aspect, an output from the line segment extraction circuit is used to determine a target area used for lens position determination from a plurality of preset focus areas. The image processing apparatus further comprises a control unit that controls the focus operation using the focus evaluation value in the target area.

(2) The image processing apparatus according to claim 4, wherein the first filter and the second filter have different sizes from each other.

[0081]

As described above, the claims 1 to 5 are as follows.
According to the invention described in (1), regarding the pixel determined to be the line segment component by the line segment extraction circuit, the generation of the false color is suppressed by suppressing the signal value of the color component, and the signal from the line segment extraction circuit is suppressed. It is also possible to calculate the focus evaluation value based on Therefore, it is possible to calculate the focus evaluation value with a simple configuration without separately providing a contrast extraction circuit or the like for calculating the focus evaluation value.

In particular, according to the invention as defined in claim 3, the suppressing means is arranged so as to correspond to the magnitude of the output from the line segment extracting circuit.
Since the degree of suppression of the signal value of the color component of the pixel is changed, it is possible to more accurately prevent the occurrence of false colors.

Further, according to the invention described in claim 4, it is possible to use an appropriate filter according to the situation.

[Brief description of drawings]

FIG. 1 is a front view showing an appearance of a digital camera 1 as an image processing apparatus according to an embodiment.

FIG. 2 is a schematic diagram showing an internal configuration of the digital camera 1.

FIG. 3 is a schematic diagram showing a configuration of an image processing circuit 20 provided inside the digital camera 1.

FIG. 4 is a diagram showing an example of a Bayer CCD.

FIG. 5 is a diagram showing a Sobel filter (3 × 3 size) and the like.

FIG. 6 is a diagram showing setting contents of an LUT 78.

7 is a diagram showing a preset focus area E0 in the image P. FIG.

FIG. 8 is a diagram showing a focus evaluation value curve L0.

FIG. 9 is a diagram showing another line segment detection filter (Prewitt filter).

FIG. 10 is a diagram showing another line segment detection filter (Forsen filter).

FIG. 11 is a diagram showing a 5 × 5 size Sobel filter.

FIG. 12 is a diagram showing three focus areas E1, E2, E3.

FIG. 13 is a diagram showing a plurality of focus areas set over the entire area of a screen P.

[Explanation of symbols]

1 digital camera 34 lens 38 Shutter button 76a Sobel filter (line segment extraction filter) 76b Absolute value addition circuit 77 Line segment extraction circuit 78 Line segment chroma killer setting LUT 9 image memory 90 memory card Cr, Cb color difference signal E0 to E3, Eij focus area L0 focus evaluation value curve Y luminance signal

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5B057 CA01 CA08 CA16 CB01 CB08                       CB16 CE06 CE17 CE18 CH09                       DC01                 5C065 AA03 CC01 CC02 DD02 GG02                       GG13                 5C077 LL17 MM03 MP08 PP01 PP27                       PP28 PP32 PP34 PP54 PQ08                       RR19 TT09                 5C079 HB01 HB04 HB11 JA23 LA06                       LA26 LA31 NA27

Claims (5)

[Claims] 1. An image processing apparatus for performing predetermined image processing on an image signal input from an image pickup device, wherein the image pickup device outputs an image signal of any one of the three primary color components. A photoelectric conversion element of a kind is arranged according to a predetermined arrangement rule for each pixel, and an interpolation process is performed using image signals of neighboring pixels with respect to image signals of each pixel input from the image pickup element, Interpolation means for outputting an image signal of three primary color components for each pixel; color space conversion means for converting an image signal of a color space having three primary color components into an image signal of a color space having a luminance component and a color component; A line segment extraction circuit that extracts a line segment component from the signal value of the luminance component; and a suppression unit that suppresses the signal value of the color component for a pixel that is determined to be a line segment component by the line segment extraction circuit, Line segment extraction times An image processing apparatus comprising: a calculating unit that calculates a focus evaluation value based on a signal from the road. 2. The image processing apparatus according to claim 1, wherein the calculation unit integrates the output from the line segment extraction circuit for a plurality of pixels within a predetermined focus area to obtain the focus evaluation value. An image processing device characterized by calculating. 3. The image processing device according to claim 1, wherein the suppressing unit changes the degree of suppression of the signal value of the color component of the pixel according to the magnitude of the output from the line segment extraction circuit. An image processing device characterized by: 4. The image processing device according to claim 1, wherein the line segment extraction circuit determines whether to suppress the signal value of the color component as a line segment extraction filter for extracting a line segment component. An image processing apparatus, characterized in that it is possible to switch between a first filter used for the above and a second filter used for calculating a focus evaluation value. 5. A predetermined type of image signal input from an image pickup device in which three types of photoelectric conversion elements for outputting image signals of any one of the three primary color components are arranged in accordance with a predetermined arrangement rule for each pixel. An image processing circuit for performing image processing, wherein interpolation processing is performed using an image signal of a pixel adjacent to an image signal of each pixel input from the image sensor, and an image signal of three primary color components is output for each pixel. Interpolating means, a color space converting means for converting an image signal of a color space having three primary color components into an image signal of a color space having a luminance component and a color component, and a line segment component from the signal value of the luminance component. A line segment extraction circuit for extracting, a pixel for which the line segment extraction circuit has determined that the pixel is a line segment component, a suppression unit for suppressing the signal value of the color component, and a focus based on the signal from the line segment extraction circuit. The image processing circuit characterized by comprising a calculating means for calculating a value, a.