JP2001128048A - Method and device for acquiring picture, method and device for processing picture and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute an appropriate sharpness emphasis processing on picture data in accordance with sampling arrangement at the time of acquiring a picture. SOLUTION: When a picture data S1 is acquired in a picture acquirement means 6, sampling information J on sampling arrangement at the time of acquiring a picture is given to the picture data S1. A picture reading means 1 reads the picture data S1 and the sampling information J and a discrimination means 2 discriminated sampling arrangement at the time of acquiring the picture based on the sampling information J. A sharpness emphasis processing means 3 executes a different sharpness emphasis processing on the picture data S1 in accordance with the discrimination result of the discrimination means 2. When the picture data S1 is pane sampling, for example, the sharpness emphasis processing for separating data into a diagonal direction is executed. Processed picture data S2 which is thus obtained is reproduced in a reproduction means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image acquisition method and apparatus for acquiring image data by acquiring an image by checkerboard sampling or square sampling, and an image processing method and apparatus for performing sharpness enhancement processing on the image data. And a computer-readable recording medium on which a program for causing a computer to execute these methods is recorded.

[0002]

2. Description of the Related Art In a digital electronic still camera (hereinafter referred to as a digital camera), an image obtained by photographing is stored as digital image data in a recording medium such as an internal memory or an IC card provided inside the digital camera.
After performing image processing such as gradation processing and sharpness enhancement processing on the stored digital image data, it is possible to reproduce an image obtained by shooting as a hard copy such as a print or as a soft copy on a display. . As described above, when reproducing an image obtained by a digital camera, it is expected that the image has the same high-quality image quality as a photograph printed from a negative film. For this reason, image data obtained by the digital camera is added with imaging information such as the presence or absence of a strobe at the time of acquiring the image, the type of illumination, etc., and is output. When performing image processing, the image data is added to the image data. There has been proposed an image reproducing method for performing more appropriate image processing on image data with reference to photographing information (Japanese Patent Laid-Open No. Hei 10-191246).

On the other hand, in order to obtain image data in a digital camera or a scanner, it is necessary to capture an image by a predetermined sampling arrangement. As a sampling arrangement for capturing such an image, in a pixel array as shown in FIG. 3, an image is arranged such that a signal value is at a position of a mark and a signal value is not at a position of a mark. Checkered sampling to capture is known. This checkered sampling is actually made up of pixels arranged as shown in FIG. 18 (a). Compared with the pixel arrangement (referred to as square sampling) shown in FIG. 18 (b), the pixels are denser. Therefore, if the area is the same, more information can be obtained. The image data of the checkerboard sampling can be obtained by photographing with a digital camera having a CCD in which the photoelectric conversion elements are arranged in a checkerboard pattern. Alternatively, the image data can be obtained by capturing the image data once in one shooting, and then capturing the second image data by shifting the CCD obliquely by 45 degrees. Further, it can be obtained by sampling image data obtained by a CCD having photoelectric conversion elements arranged in a square shape in a checkered pattern.

However, in an image output apparatus for outputting to an image output medium such as a CRT monitor or print paper, or an image processing apparatus for performing sharpness enhancement processing or the like on image data as described above, all of the ○ marks and X marks are used. The square-sampled image data having the signal value at the position of is displayed or processed. In particular, in the sharpness enhancement processing in the above-described image processing, the image processing is suitable for square sampling image data.
Processing that can be separated in the vertical and horizontal directions of the image is performed. Therefore, for the image data on which the checkered sampling has been performed, the signal value at the position of the cross is calculated by performing an interpolation operation on the signal value at the position of the mark, and the image data is converted from the checkered sampling to the square sampling. After that, display and image processing are performed.

[0005]

When the frequency characteristics of the checkered sampled image data described above are represented two-dimensionally, the response becomes a diamond-shaped response as shown in FIG. 19A, and the frequency characteristics of the square sampled image data are represented. Is FIG.
A rectangular response as shown in FIG. In addition,
In FIG. 19, fs / 2 is the Nyquist frequency of the square-sampled image data, and in FIGS. 19A and 19B, the frequency band in which the image can be reproduced is indicated by a solid line. Here, even if the image data sampled in a checkered pattern is converted to square sampling, the frequency characteristic expressing the original image information remains unchanged in FIG. For this reason, when image data sampled in a checkered pattern is subjected to sharpness enhancement processing that can be separated in the vertical and horizontal directions of the image in the same manner as the square sampling, original image information corresponding to the diagonal lines in FIG. Noise is generated due to the emphasis on the frequency band that does not exist, and as a result, the image quality of the image obtained by performing the processing is deteriorated.

The present invention has been made in view of the above circumstances, and provides an image acquisition method and apparatus capable of acquiring image data capable of performing sharpness enhancement processing without generating noise, and an image acquisition method and apparatus. An image processing method and apparatus for performing sharpness enhancement processing on acquired image data, and a computer-readable recording medium on which a program for causing a computer to execute the image acquisition method and the image processing method is recorded. It is assumed that.

[0007]

According to the present invention, there is provided an image acquiring method, comprising: acquiring an image by a predetermined sampling arrangement;
An image acquisition method for acquiring image data representing the image, wherein sampling information on the predetermined sampling arrangement is added to the image data.

[0008] Here, "giving sampling information"
As a method, the sampling information is described in a file header of the image data, a file different from the image data is created on a recording medium for recording the image data, and the sampling information is described therein, When recording on a recording medium, various methods can be adopted, such as creating a file describing information about image data and describing sampling information in this file.

The "sampling information" is preferably information capable of distinguishing between checkerboard sampling and square sampling. Symbols representing checkerboard sampling and square sampling, respectively, and, in addition to these symbols, pixels at the time of image capture. The number, or information indicating the frequency characteristics of each sampling arrangement can be employed.

[0010] An image processing method according to the present invention is an image processing method for performing sharpness enhancement processing on image data obtained by the image obtaining method according to the present invention, and performs image processing on the image data in accordance with the sampling information. It is characterized in that processed image data is obtained by performing different sharpness enhancement processing.

Here, "different sharpness enhancement processing"
This means that the direction in which processing is performed on an image represented by image data is different, such as processing that can separate vertical and horizontal sharpness enhancement processing or processing that can be separated diagonally according to the sampling arrangement. In the case where the filtering process is performed by the one-dimensional sharpness enhancement filter, the direction in which the filtering process is performed is different depending on the sampling arrangement.

[0012] In the image processing method according to the present invention, it is preferable that the different sharpness enhancement process is a process according to a frequency characteristic of the image data caused by the sampling arrangement.

An image acquiring apparatus according to the present invention is an image acquiring apparatus for acquiring an image by a predetermined sampling arrangement and acquiring image data representing the image, wherein sampling information on the predetermined sampling arrangement is included in the image data. The present invention is characterized in that it is provided with an applying means for applying.

In the image acquisition apparatus according to the present invention, it is preferable that the sampling information is information for distinguishing between checkerboard sampling and square sampling.

An image processing apparatus according to the present invention is an image processing apparatus comprising processing means for performing sharpness enhancement processing on image data obtained by the image obtaining apparatus according to the present invention, wherein the processing means A means for performing different sharpness enhancement processing on the image data according to information to obtain processed image data.

In the image processing apparatus according to the present invention, it is preferable that the processing means is means for performing the different sharpness enhancement processing in accordance with a frequency characteristic caused by the sampling arrangement of the image data. .

Further, when an image is captured by a predetermined sampling arrangement, image data in a format accompanied by sampling information on the predetermined sampling arrangement may be recorded on a computer-readable recording medium and provided. .

The image acquisition method and the image processing method according to the present invention may be provided by being recorded in a computer-readable recording medium as a program for causing a computer to execute the method.

Further, the image processing device according to the present invention may be provided in an image pickup device such as a digital camera, or may be provided in an output device such as a printer.

[0020]

According to the image acquisition method and apparatus according to the present invention, the sampling information relating to the sampling arrangement at the time of image capture is added to the image data. Therefore, the image acquisition method according to the present invention can be performed by referring to the sampling information. In addition, image processing such as sharpness enhancement can be performed on image data obtained by the apparatus in accordance with the sampling arrangement at the time of image capture.

Further, according to the image processing method and apparatus according to the present invention, different sharpness enhancement processing is performed on image data in accordance with sampling information relating to a predetermined sampling arrangement when capturing an image. Regardless of the arrangement, sharpness enhancement processing can be performed so as not to generate noise, whereby processed image data capable of reproducing high-quality images without noise can be obtained.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of an image output system to which an image processing device according to an embodiment of the present invention is applied. As shown in FIG. 1, the image output system according to the present embodiment acquires image data S1 by capturing an image with a predetermined sampling arrangement, and adds sampling information J on the sampling arrangement to the image data S1 for output. Image reading means 1 for performing processing on image data S1 output from image acquiring means 6 to perform image reading;
Based on the sampling information J given to the image data S1, a determining unit 2 that determines whether the sampling arrangement when the image data S1 is captured by the image obtaining unit 6 is a checkerboard sampling or a square sampling, and a determining unit 2
A sharpness enhancement processing unit 3 that performs different sharpness enhancement processing on the image data S1 based on the determination result in to obtain processed image data S2, and a reproduction unit 4 that reproduces the processed image data S2.

FIG. 2 is a block diagram showing an example of the image acquisition means 6. As shown in FIG. 2, the image acquisition unit 6 is, for example, a digital camera, and captures an image of a scene by checkerboard sampling to obtain image data S0 representing the image.
D7, a checkerboard square conversion unit 8 that performs an interpolation operation on the checkerboard-sampled image data S0 to convert the sampling arrangement of the image data S0 from the checkerboard sampling to the squarer sampling to obtain the squarer-sampled image data S1; The information on the sampling arrangement when the image is captured is referred to as sampling information J, and this is referred to as image data S1.
And recording means 9 for recording the data on a medium 10 such as a memory card. When the CCD 7 is originally square sampling, the image acquisition means 6 is not provided with the checkerboard square conversion means 8 and the image data S0 obtained by the CCD 7 is used as the image data S1 together with the sampling information J as the media data S1. Will be recorded.

On the other hand, when the image acquisition means 6 is a scanner that reads the image photoelectrically, the image can be captured by checkerboard sampling by shifting the sample and hold position by half a pixel for each scan of one line. The obtained image data S0 is sampled in a checkered pattern. In this case, the scanner is provided with a checkerboard square conversion unit 8 shown in FIG. 2, whereby the sampling arrangement of the image data S0 is converted from checkerboard sampling to square sampling, and square sampling image data S1 is obtained.

In the case where the image data S0 is sampled in a checkered pattern, as shown in FIG. 3, it is assumed that a pixel value of a circle has a signal value but a pixel value of a cross does not have a signal value. Become. Therefore, the Ichimatsu square conversion means 8 performs an interpolation operation using the signal value at the pixel position,
X The signal value at the pixel position is obtained.

Here, when the frequency characteristic when the image data S0 is sampled in a checkered manner is represented in two dimensions, the frequency characteristic has a diamond-shaped response as shown in FIG. In FIG. 4, the frequency band in which the checkered sampled image data S0 can be represented is shown by a solid line, and even if the image data S0 is converted to square sampling, the frequency band representing the original image is not changed. This frequency characteristic is not changed.

The recording means 9 adds the sampling information J to the image data S1 and records it on the medium 10. As a method of providing the media 10, the sampling information J is described in the file header of the image data S 1.
When the plurality of image data sets S1 are recorded on the medium 10 in which the image data sets S1 and the sampling information J are described in separate files, a file describing the information about the image data sets S1 is created. Various methods can be adopted, such as describing

Here, as the sampling information J, a symbol indicating the distinction between the checkerboard sampling and the square sampling, a symbol indicating the distinction between the checkerboard sampling and the square sampling, the number of pixels at the time of image capture, and information indicating the frequency characteristics of the image data S0. And the like. Note that if the number of pixels at the time of capturing the image is known, the Nyquist frequency of the image represented by the image data S0 can be obtained, and if the sampling arrangement of the image data S0 is known, the Nyquist frequency is used as shown in FIG. Frequency characteristics can be obtained. Further, as the information indicating the frequency characteristic, for example, in the frequency characteristic shown in FIG. 4, coordinate values of four points which are the vertices of the characteristic can be used, and if these coordinate values are known, the frequency characteristic as shown in FIG. You can ask.

Note that the sampling information J is not limited to these. If the image data S0 is square sampling, no information may be added to the image data S0. If the sampling arrangement can be specified accordingly, it may be information on the model.

Returning to FIG. 1, the judging means 2 judges the sampling arrangement at the time of capturing an image based on the sampling information J. Here, if the sampling information J is a symbol representing checkerboard sampling and square sampling, the symbol is determined. If the sampling information J includes the number of pixels at the time of image capture in addition to this symbol, the symbol is replaced. At the same time, the frequency characteristics of the image data S1 are also determined. When the sampling information J is information indicating the frequency characteristics of the image data S1, the sampling arrangement is determined from the response shape represented by the frequency characteristics.

The sharpness enhancement processing means 3 performs different sharpness enhancement processing on the image data S1 according to the determination result of the determination means 2 to obtain processed image data S2. First, when it is determined that the sampling arrangement at the time of capturing an image is square sampling, normal sharpness enhancement processing (hereinafter referred to as first sharpness enhancement processing) is performed. Here, the first sharpness enhancement processing refers to the X direction and the Y direction in the pixel arrangement of the image represented by the image data S1 (see FIG. 5).
A process that can be separated in a direction. Specifically, first, a sharpness enhancement process may be performed in the X direction by the following equation (1), and then a sharpness enhancement process may be similarly performed in the Y direction. When calculating the image data Sus, a process using an M × M rectangular mask may be used. Further, FIG.
The filtering may be performed in the X direction and the Y direction of the image data S1 in order by a one-dimensional filter having the frequency characteristic shown in FIG.

S2 = S1 + β (S1−Sus) (1) where β: enhancement coefficient Sus: blurred image data of S1, for example, Sus = ΣS
1 / M × M (M is the mask size) If the frequency characteristics of the image data S1 can be recognized from the sampling information J, the mask size and the response of the one-dimensional filter can be changed according to the frequency characteristics. Thus, sharpness enhancement processing according to the frequency characteristics of the image data S1 can be performed.

FIG. 7A shows the frequency characteristics of the square sampling. As shown in FIG. 7A, the frequency characteristic in the case of square sampling has a rectangular response, but the first sharpness enhancement process emphasizes the frequency band indicated by the hatched portion in FIG. Image data S
1 is enhanced and the processed image data S2
Is obtained.

On the other hand, when it is determined that the sampling arrangement at the time of capturing the image is the checkerboard sampling, unlike the square sampling, the pixel arrangement of the image represented by the image data S1 (see FIG. 5). , A sharpness enhancement process that can be separated in the diagonal direction (hereinafter referred to as a second sharpness enhancement process) is performed. For example, first X =
After performing the sharpness enhancement processing in the Y direction (the direction of the arrow A in FIG. 5) by the above equation (1), the sharpness enhancement processing is similarly performed in the X = −Y direction (the direction of the arrow B in FIG. 5). This processing may be performed, and when calculating the blurred image data Sus in this processing, a processing using a diamond-shaped mask as shown in FIG. 8 may be performed. further,
The sharpness may be enhanced by performing a filtering process in the direction of arrow A and the direction of arrow B in order by a one-dimensional filter having a frequency characteristic as shown in FIG.

Here, the frequency characteristic of the checkerboard sampling is as shown in FIG. 4, and the second sharpness enhancement process emphasizes the frequency band of the hatched portion as shown in FIG. 9 to reduce the sharpness of the image data S1. The emphasized and processed image data S2 is obtained.

Here, comparing FIG. 7 and FIG. 9, it is found that, in the checkerboard sampling, the information of the square portion in the square sampling characteristic is missing, so that sharpness enhancement processing similar to the square sampling is performed. The information of the missing part is emphasized, and the emphasized information appears as noise on the image represented by the processed image data S2. However, by performing the second sharpness emphasis processing, the checkerboard sampling is performed. Since the sharpness enhancement process is performed according to the characteristics of the frequency band described above, it is possible to prevent noise from occurring in an image obtained by reproducing the processed image data S2.

The reproducing means 4 can reproduce the processed image data S2 as a visible image, such as a hard copy device such as a digital photographic silver halide printer and an ink jet printer, and a soft copy device such as a CRT and a liquid crystal display.

Next, the operation of this embodiment will be described. FIG. 10 is a flowchart showing the operation of the present embodiment. As shown in FIG. 10, first, the image data S1 and the sampling information J acquired by the image acquisition unit 6 are obtained.
Is read by the image reading means 1 and input to the sharpness enhancement processing means 3 and the determination means 2 (step S1). In the determination means 2, the sampling information J
It is determined whether the sampling arrangement at the time of capturing the image data S0 is checkerboard sampling or square sampling based on (step S2). If the result of the determination is square sampling (step S
3) The first sharpness enhancement processing is performed on the image data S0 by the sharpness enhancement processing means 3 to obtain processed image data S2 (step S4).
The processed image data S2 is reproduced by the reproducing means 4 (step S5), and the processing is terminated.

On the other hand, if the discrimination result is the checkerboard sampling, step S3 is denied, and the second sharpness enhancement process is performed on the image data S1 to obtain the processed image data S2 (step S6). . The processed image data S2 is reproduced by the reproducing means 4 (step S5), and the processing is terminated.

As described above, in the present embodiment, different sharpness enhancement processing is performed on the image data S1 in accordance with the sampling information J at the time of capturing an image. Therefore, the image data S1 is sampled by checkerboard sampling. Even if the image data is processed, sharpness enhancement processing can be performed so as not to generate noise, so that processed image data S2 that can reproduce a high-quality image without noise can be obtained.

In the above embodiment, when the image data S0 is a checkered sampling, the image acquisition means 6
Has been converted to square sampling, but the image acquisition means 6 does not convert to square sampling.
The image data S0 is stored in the media 10 with the checkered sampling.
May be recorded. In this case, the image processing apparatus is provided with an interpolation means for converting the checkered sampling into the square sampling before the sharpness enhancement processing means 3, and the square sampling image data S1
Can be obtained. Then, by determining whether or not the checkerboard sampling is converted to square sampling by the interpolator, the determiner 2 determines whether the sampling arrangement at the time of capturing the image is checkerboard sampling or square sampling, The sharpness enhancement processing in the sharpness enhancement processing means 3 can be switched.

Further, in the above embodiment, the image data S1 obtained by the image obtaining means 6 is recorded on the medium 10 together with the sampling information J, and the image reading means 1
, The image data S1 may be transferred to the image reading means 1 via the network together with the sampling information J. In this case, an interface for connecting the image acquiring unit 6 and the image reading unit 1 is used instead of the recording unit 9 of the image acquiring unit 6.

Next, another embodiment of the image processing apparatus for processing image data using the sampling information obtained by the image acquisition apparatus according to the present invention will be described. FIG. 11 is a schematic block diagram showing a configuration of an image output system to which an image processing device according to another embodiment of the present invention is applied. As shown in FIG. 11, the image output system performs processing on the image data S1 output from the image acquisition unit 6, and performs image processing similar to that of the embodiment shown in FIG. Means 2, a reproducing means 4, and an image processing means 23 for performing image processing including a conversion process to be described later on the image data S1 to obtain processed image data S3 based on the result of the judgment by the judging means 2. . It should be noted that in the checker square conversion unit 8 of the image acquisition unit 6 of another embodiment, for example,
As described in 5857, an interpolation operation is performed by using a linear interpolation filter as shown in FIG. 12 using the signal value of the pixel position, the signal value of the pixel position is obtained, and the square sampling image data S1 is obtained. Shall be obtained.

The image processing means 23 performs image processing on the image data S1 in accordance with the result of the discrimination by the discriminating means 2 as described below to obtain processed image data S3. FIG. 13 is a schematic block diagram showing the configuration of the image processing means 23. As shown in FIG. 13, when the image acquisition unit 6 determines that the sampling arrangement at the time of capturing the image is the checkerboard sampling, the image processing unit 23 outputs only the signal value at the pixel position of the image data S1. The interpolation filter F described later is used for the image data S1.
A conversion processing means 12 for performing an interpolation operation by 0 to obtain new square-sampled image data S1 '; and an image data S1' for which image processing such as gradation processing and sharpness enhancement processing has been performed. Processing means 13 for obtaining S3. When it is determined that the sampling arrangement at the time of capturing the image is square sampling, the conversion processing means 12 outputs the image data S1 without performing any processing.

The conversion processing means 12 performs an interpolation operation on the image data S1 as follows. As shown in FIG. 3, the checkered sampled image data S
0 indicates that the pixel has a signal value at the pixel position, but does not have a signal value at the pixel position. On the other hand, the square-sampling image data S1 has a signal value at the x pixel position, which is obtained by the image acquisition means 6 by an interpolation operation using a linear interpolation filter having the characteristics shown in FIG. Therefore, the image represented by the image data S1 has a large blur. For this reason, the conversion processing means 12 uses the interpolation filter F0 having the coefficients shown in FIG.
1 to obtain a signal value at the x pixel position by replacing the signal value with the signal value at the x pixel position in the image data S1, thereby obtaining new square sampled image data S1 '. . In addition,
This filtering processing refers to convolving the filter coefficient of the interpolation filter F0 with the signal value at the pixel position.

The interpolation filter F0 is created as follows. First, the interpolation coefficient of the one-dimensional Cubic spline interpolation operation for finding the signal value at the midpoint of four pixels is
Since they are -1/16, 9/16, 9/16, and -1/16, when these are expanded in two dimensions, as shown in FIG.
4 is an interpolation filter composed of four coefficient matrices. Then, by rotating the arrangement of the filter coefficients of the interpolation filter by 45 degrees, an interpolation filter F0 having the arrangement of the filter coefficients shown in FIG. 13 is obtained.

Here, a higher-order interpolation operation such as a Cubic spline interpolation operation can interpolate an image without blurring the image and without impairing the reproduction range of the original image. The checkered sampling shown in FIG.
Compared with the square sampling having a signal value also at the position of the cross, the frequency characteristic of the image is inclined in a direction rotated by 45 degrees. Therefore, the interpolation filter F0 shown in FIG. 13 obtained by rotating the arrangement of the filter coefficients of the interpolation filter performing the Cubic spline interpolation calculation shown in FIG.
Accordingly, if the interpolation operation is performed using only the signal value at the pixel position of the image data S1, the image represented by the obtained image data S1 'can be interpolated as shown in FIG. As in the case where the filtering process by the filter is performed, there is no blurring of the image and no loss of the reproduction range of the original image.

Next, the operation of another embodiment will be described. FIG. 15 is a flowchart showing the operation of another embodiment. As shown in FIG. 15, first, the image data S1 and the sampling information J obtained by the image obtaining unit 6 are read by the image reading unit 1 and input to the image processing unit 23 and the determination unit 2 (Step S1).
1). The discriminating means 2 discriminates, based on the sampling information J, whether the sampling arrangement when the image is captured by the image acquiring means 6 is checkerboard sampling or square sampling (step S12). If the result of the determination is square sampling (step S13), the image processing unit 23 performs only image processing in the processing unit 13 on the image data S1 to obtain processed image data S3 (step S13). Step S
14). The processed image data S3 is reproduced by the reproducing means 4 (step S15), and the processing ends.

On the other hand, if the result of the determination is checkerboard sampling, step S13 is negative, and the conversion processing means 1
In step 2, an interpolation operation is performed on the image data S1 by the interpolation filter F0 to obtain new square-sampled image data S1 '(step S16). And
Image processing is performed by the processing means 13 on the new square-sampled image data S1 'to obtain processed image data S3 (step S14). The processed image data S3 is reproduced by the reproducing means 4 (Step S
15), end the processing.

As described above, in another embodiment, if it is determined that an image has been captured by checkerboard sampling based on the sampling information J at the time of capturing the image, the image acquisition means 6 A new square sampling image data S1 'is obtained by generating a signal value at the x pixel position by an interpolation calculation using an interpolation filter F0 different from the interpolation calculation performed in the above, so that a new square sampling image is obtained. The data S1 'is the image data S
As compared with 1, the image is less blurred. Therefore, by performing image processing on the new image data S1 ', a high-quality image with less blur can be obtained.

In the other embodiment, the conversion processing means 12 performs the interpolation operation using the interpolation filter F0 as shown in FIG. 13. However, as shown in FIG. May be interpolated filters arranged in a checkered pattern. Further, as shown in FIG. 17, a square interpolation filter in which 0 is interpolated between the filter coefficients of the interpolation filter F0 may be used. Here, FIGS.
When the interpolation filter shown in (1) is used, the amount of calculation for multiplying by 0 increases. For example, a DSP (Digital Sign
(Al Processor), when a calculation element dedicated to the product-sum operation is implemented, the calculation can be performed at higher speed by performing the calculation only by a simple product-sum operation. Therefore, by using such an operation element dedicated to the product-sum operation, even if the operation amount increases, the filtering process is performed by the interpolation filter F0 without increasing the operation time.
The square sampling image data S1 can be obtained.

In the above other embodiment, Cubi
c Although an interpolation filter is used to perform spline interpolation, any interpolation filter that performs higher-order interpolation, such as B-spline interpolation or Lagrange interpolation, should be used. Can be. Also,
Although a 4 × 4 interpolation filter is used, the present invention is not limited to this, and any filter can be used as long as one of N and M is 3 or more.

Further, in each of the above embodiments,
Although the image processing device according to the present invention is provided in the image output system, the image processing device may be provided in an imaging device such as a digital camera or a scanner that reads an image from a film, and a monitor that reproduces image data obtained by these imaging devices and It may be provided in an output device such as a printer. Of course, the image processing apparatus may be used alone.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram illustrating a configuration of an image output system to which an image processing device according to an embodiment of the present invention is applied.

FIG. 2 is a schematic block diagram illustrating a configuration of an image acquisition unit.

FIG. 3 is a diagram showing a pixel arrangement of image data sampled in a checkered pattern;

FIG. 4 is a diagram showing frequency characteristics of checkerboard sampling;

FIG. 5 is a diagram showing a pixel arrangement of image data of square sampling;

FIG. 6 is a diagram illustrating frequency characteristics of a one-dimensional filter that performs sharpness enhancement processing;

FIG. 7 is a diagram showing a frequency characteristic of square sampling and an emphasis frequency range in the first sharpness emphasis processing;

FIG. 8 is a diagram for explaining a method of calculating blurred image data in a second sharpness enhancement process;

FIG. 9 is a diagram showing an emphasis frequency range in a second sharpness emphasis process;

FIG. 10 is a flowchart showing the operation of the embodiment.

FIG. 11 is a schematic block diagram illustrating a configuration of an image output system to which an image processing device according to another embodiment of the present invention is applied.

FIG. 12 is a diagram showing a linear interpolation filter.

FIG. 13 is a schematic block diagram illustrating a configuration of an image processing unit.

FIG. 14 is a diagram illustrating an interpolation filter that performs a two-dimensional Cubic spline interpolation operation;

FIG. 15 is a flowchart showing the operation of another embodiment.

FIG. 16 is a diagram showing another example of the interpolation filter.

FIG. 17 is a diagram showing another example of the interpolation filter.

FIG. 18 is a diagram showing a pixel arrangement of checkerboard sampling and square sampling.

FIG. 19 is a diagram showing frequency characteristics of checkerboard sampling and square sampling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading means 2 Discriminating means 3 Sharpness enhancement processing means 4 Reproduction means 6 Image acquisition means 7 CCD 8 Ichimatsu Masakata conversion means 9 Recording means 10 Media 12 Conversion processing means 13 Processing means 23 Image processing means

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Claims (15)

[Claims] 1. An image acquisition method for acquiring an image by a predetermined sampling arrangement and acquiring image data representing the image, wherein sampling information on the predetermined sampling arrangement is added to the image data. Image acquisition method. 2. The image acquisition method according to claim 1, wherein the sampling information is information for distinguishing between checkerboard sampling and square sampling. 3. An image processing method for performing sharpness enhancement processing on image data acquired by the image acquisition method according to claim 1 or 2, wherein a different sharpness is applied to the image data according to the sampling information. An image processing method characterized in that processed image data is obtained by performing an emphasis process. 4. The different sharpness enhancement processing includes:
4. The image processing method according to claim 3, wherein the image data is processed in accordance with a frequency characteristic caused by the sampling arrangement. 5. An image acquisition apparatus for capturing an image by a predetermined sampling arrangement and acquiring image data representing the image, comprising: an assigning means for adding sampling information on the predetermined sampling arrangement to the image data. An image acquisition apparatus characterized in that: 6. The image acquisition apparatus according to claim 5, wherein the sampling information is information for distinguishing between checkerboard sampling and square sampling. 7. An image processing apparatus comprising processing means for performing sharpness enhancement processing on image data obtained by the image obtaining apparatus according to claim 5 or 6, wherein said processing means outputs An image processing apparatus, which is means for performing different sharpness enhancement processing on the image data in accordance with the image data to obtain processed image data. 8. The image processing apparatus according to claim 7, wherein said processing means performs the different sharpness enhancement processing in accordance with a frequency characteristic caused by the sampling arrangement of the image data. apparatus. 9. A computer-readable recording medium recording a program for causing a computer to execute an image acquisition method for acquiring an image data representing the image by capturing the image by a predetermined sampling arrangement, wherein the program is A computer-readable recording medium having a procedure for adding sampling information relating to the predetermined sampling arrangement to the image data. 10. The computer-readable recording medium according to claim 9, wherein said sampling information is information for distinguishing between checkerboard sampling and square sampling. 11. A computer-readable recording medium storing a program for causing a computer to execute an image processing method for performing sharpness enhancement processing on image data obtained by the image obtaining method according to claim 1 or 2. A computer-readable recording medium, characterized in that the program has a procedure of performing different sharpness enhancement processing on the image data according to the sampling information to obtain processed image data. 12. The method according to claim 1, wherein the step of obtaining the processed image data is a step in which the different sharpness enhancement processing is performed according to a frequency characteristic of the image data caused by the sampling arrangement. 12. The computer-readable recording medium according to item 11. 13. A computer-readable recording medium for recording image data in a format to which sampling information related to the predetermined sampling arrangement is attached when an image is captured by the predetermined sampling arrangement. 14. An imaging device comprising the image processing device according to claim 7. Description: 15. An output device comprising the image processing device according to claim 7. Description: