JP2001061092A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve quality of displayed and recorded images and enhance the processing speed of images by providing an interpolation means to form an image for display and an image for recording respectively with interpolation by an approximate expression of a high-order polynomial equal to or higher than a third order polynomial. SOLUTION: Original image data from a built-in memory 30 is inputted in an interpolating position calculating part 91 and an arithmetic interpolation part 94. The output value at a desired position is obtained by using the approximate expression by the high-order polynomial at least equal to or higher than the third order polynomial to enhance interpolation accuracy based on the inputted data by the interpolating position calculating part 91. Next, an interpolating position is corrected based on data from a memory area 31 by an interpolating position correcting part 92. Thus, since the output at the corrected interpolating position is calculated by using a beforehand prepared interpolation coefficient table 93 by correcting the interpolating position, the output value at the interpolating position is calculated at high speed without complicated calculation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera capable of capturing a desired image and recording and displaying this image information.

[0002]

2. Description of the Related Art Electronic cameras are configured to display and record images. Recently, some electronic cameras can display and record not only still images but also moving images. Therefore, an attempt has been made to record a still image with high image quality while sharing the recording process of a still image and a moving image (Japanese Patent Laid-Open No. 10-108121).

Attempts have also been made to perform cubic interpolation on a part of the number of pixels when converting the number of pixels according to the format (Japanese Patent Laid-Open No. Hei 10-191392).

[0004]

However, in the above-mentioned attempts, no proposal has been made to improve the quality of displayed and recorded images and to speed up the processing thereof.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic camera which improves the quality of displayed and recorded images and speeds up the processing thereof.

[0006]

According to the present invention, the following means have been taken in order to solve the above-mentioned problems.

An electronic camera according to the present invention is an electronic camera capable of capturing an image of a subject, displaying and recording the captured image of the subject, and forming a display image and a recording image based on the captured image. The image processing apparatus further includes an interpolation unit that forms the display image and the recording image by an interpolation process using an approximate expression of a third-order or higher-order polynomial. Since high-precision interpolation processing is performed for both display and recording, image quality can be improved in both display and recording.

A preferred embodiment of the above electronic camera is as follows.

(1) When forming the display image and the recording image, the interpolation means forms an image under interpolation conditions according to the formed image. Since interpolation is performed under conditions corresponding to the respective resolutions of display and recording, processing efficiency and speed can be improved. Here, the interpolation condition includes a condition relating to interpolation accuracy or the number of interpolation data. Since interpolation conditions are determined for each accuracy or data, efficient processing can be performed.

(2) The interpolation means includes a first interpolation means for forming the display image and a second interpolation means for forming the recording image. Since dedicated interpolation means is provided for each of display and recording, the processing can be speeded up.

(3) The interpolation means includes means for storing interpolation coefficient information which is used at least partially in common when forming the display image and the recording image,
Forming the display image and the recording image using the interpolation coefficient information. Since the interpolation value is calculated from the interpolation coefficient information, a complicated circuit is not required, and a high-speed and high-precision interpolation result can be obtained with a simple circuit. Further, since the interpolation coefficient information is partially shared between the case of display and the case of recording, memory can be saved.

(4) The image processing apparatus further comprises a storage unit for storing the captured image data, wherein the unit for forming the display image and the unit for forming the recording image read the captured image data from the storage unit, and Forming a display image and the recording image. Since (the original data of) the captured image is shared between the display and the recording, the memory can be saved.

[0013]

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

FIG. 1 is a schematic block diagram showing a system configuration of an electronic camera according to one embodiment of the present invention.

A schematic configuration of an electronic camera according to the present invention will be described with reference to FIG.

An image of a subject that has passed through the photographing lens system 11 is converted into an electric signal by the image pickup device 12. Image sensor 1
The electric signal converted in 2 is converted into an analog image signal by the imaging circuit 13 and then converted into a digital image signal by the A / D converter 14. Then, the digital image signal is subjected to a predetermined process and, for example, an interface (I / I / O) to a detachable removable memory 20 (for example, a flash memory, a smart media, or the like) as an external memory.
F) recorded via 21; The removable memory 20 is usually mounted in the card slot 22. Further, the electronic camera has a high-speed built-in memory 30 (for example, a random access memory (RAM) or the like), and serves as a working memory in image compression / expansion or as a high-speed buffer as a temporary image storage unit. used. The built-in memory 30 has a memory area 31 for interpolation processing in the present invention. The memory area 31 may be a memory independent of the built-in memory 30, or may be a memory built in an arithmetic circuit (or IC) for interpolation processing.

The compression / expansion circuit 40 is for compressing the digital image signal and for expanding (expanding) the compressed image signal.

The electronic camera is equipped with an LCD 50 (liquid crystal display) for normal image display.
The CD 50 displays an image recorded in the removable memory 20 and an image to be photographed. This LCD 50
The image displayed on the LCD is temporarily fetched from the built-in memory 30 into the video memory 51 and then converted into a video image by the video output circuit 52 so that the image can be displayed on the image display LCD 50. The video output circuit 5
The second output is capable of outputting a video image to an external display device via an external terminal 53 for video output.

The system controller 70 controls the entire device of the electronic camera, and its function will be described later in detail. The system controller 70 receives an input from the operation unit 73 composed of a release, performs imaging by operating the release, and requests an image processing circuit (not shown) to perform image processing. In addition, when the amount of light at the time of imaging the subject is insufficient, the system controller 70 requests the strobe light emitting unit 71 to turn on the strobe and perform shooting. Further, the system controller 70 has an unillustrated photographing distance detecting unit, which has a function of detecting a distance to a subject. The operation unit 73 can also set various modes, and the mode settings are displayed on the mode LCD.

External interface (external I / F) 61
Is connected to the external input / output terminal 60 to input / output data to / from an external device. For example, a personal computer or the like is connected to the external input / output terminal 60 to transfer an image in the detachable memory 20 to the personal computer or the like and to input image data from the personal computer or the like.

Each section of the electronic camera is basically driven by a battery, and each section of the camera is driven by electric power from a camera battery 81 via a power supply section 80. The camera battery 81 is connected to the power supply unit 8.
It can be charged by the control of 0.

FIG. 2 is a diagram showing a one-dimensional interpolation model. Conventionally, as shown in FIG. 2A, linear interpolation for calculating an output value at a desired position by a straight line connecting two points has been generally used. In this way, the position having a known output value required for calculation may be two points. However, since the output value of the proportional average between the two points is determined, for example, the maximum value or the maximum value between the two points is obtained. Even if there is a minimum value, it cannot be detected. In the present invention, in order to increase the interpolation accuracy, an output value at a desired position is obtained using an approximate expression based on at least a third-order or higher-order polynomial. FIG. 2 shows an example in which a coefficient of a third-order polynomial is obtained from the values of four points, and position data is inserted into an approximate expression based on the obtained third-order polynomial to obtain an output. Note that the interpolation using the approximate expression using the third-order polynomial is also referred to as “Cubic interpolation”. In FIG. 2, a coefficient of a third-order polynomial is obtained from output values of four points at positions n-1, n, n + 1, and n + 2, and an output value at a position x 'is obtained from the third-order polynomial to obtain an interpolation value at a desired position. Is obtained. In consideration of the case where this is performed by, for example, linear interpolation, the position having the maximum value is n + 1. Therefore, it is clear that an accurate position cannot be obtained unlike the case of the present invention.

FIG. 3 shows an interpolation operation circuit 90 according to the present invention.
It is a block diagram of. The interpolation calculation circuit 90 includes an interpolation position calculation unit 91, an interpolation position correction unit 92, and an interpolation coefficient table 9
3, the interpolation calculation unit 94, and the buffer memory 31. The functions of the interpolation position calculator 91 to the interpolation calculator 94 are performed by the system controller 70. Specifically, the interpolation operation circuit 90 performs the following operation.

The original image data from the built-in memory 30 is input to the interpolation position calculator 91 and the interpolation calculator 94. The interpolation position calculation unit 91 may be configured, for example, as shown in FIG.
(B) Interpolation position x 'between point n and point n + 1
Is calculated. Next, in order to simplify the calculation, the interpolation position correction unit 92 sets the interpolation position from the memory area 31 to a point closest to the point x ′ when the distance between the point n and the point n + 1 is divided into 16 equal parts. Modify based on the data in By correcting the interpolation position in this way, it is possible to calculate the output at the corrected interpolation position using the interpolation coefficient table 93 prepared in advance, so that the interpolation position can be calculated at high speed without performing complicated calculations. The output value can be calculated. It should be noted that the error caused by the correction of the interpolation position is not realistic because the interpolation coefficient is given in the table.
If the positions are equally divided, the accuracy is sufficient, and the amount of data does not increase so much.

FIG. 4 is a block diagram showing the flow of the display and recording process according to the present invention. In FIG. 4, an image of a subject that has passed through a photographing lens is converted into an electric signal by a CCD. The electric signal converted by the CCD is converted into an analog image signal by an imaging circuit (not shown), and then converted into a digital image signal by an A / D converter. And
The digital image signal is temporarily stored in a built-in memory (hereinafter, referred to as “shared memory”). The digital image signal stored in the shared memory is divided into two processing routes: image processing for display and image processing for recording. The image processing for display and recording is image processing for enlarging or reducing a normal image (referred to as resizing for display and resizing for recording, respectively). In the resizing process, an interpolation process using an approximate expression using a high-order polynomial that can obtain high accuracy is used. An image having a desired number of pixels (that is, image quality) obtained by this interpolation processing is processed as follows. First, in the case of display, for example, character data or the like is added to the processed image data by the mixer and displayed on an LCD, for example, via an interface. In the case of recording, the processed image data is processed by a compression circuit, for example, in JP
It is compressed in the EG format and recorded in the removable memory. In these processes, the interpolation process may be shared for display and recording, or may be separately provided for high-speed processing, and may be independently operable.

In FIG. 4, before the resizing for recording, an image picked up by a single plate may be turned into a pseudo three plates by an interpolation process using an approximate expression using a higher-order polynomial. In this case, pseudo-three-plate conversion means that an image photographed by an image sensor composed of a single plate (or two plates) can be obtained as if R
(Red), G (green), and B (blue).

FIG. 5 is a block diagram showing a modification of FIG. In FIG. 5, the image information called from the built-in memory is resized to an image having the number of pixels (for example, 640 × 480 pixels) that becomes desired recording image information (referred to as resize 1). At this time, an interpolation process using an approximate expression using a high-order polynomial according to the present invention is performed. Since this image is a recording image, it is recorded as it is in an external memory such as a detachable memory, for example, after image compression by JPEG. When displaying an image on an LCD or the like, the number of display pixels is often different from 640 × 480 pixels at the time of recording as described above, and therefore, it is necessary to resize for display (resize 2). ). At this time, it is preferable to create an image for display by interpolation processing using an approximate expression using a higher-order polynomial. In this case, the size of the image for recording and the size of the image for display are usually some extent. Fixed. That is, in the case of recording, the image size is, for example, 640 × 480 pixels described above, or in the case of high image quality, 800 × 600 pixels or 1024 × 768 pixels. The number of display pixels may be the same as the number of recording pixels in some cases, in addition to the case described above. As described above, since the number of pixels of an image related to recording or display is often determined in advance, as shown in FIG. 5, when resizing an image for display (resizing 2), a high-order polynomial is used. It is preferable to resize using a coefficient (fixed coefficient) obtained in advance by an approximate expression using a higher-order polynomial in order to reduce the processing without using an interpolation process using an approximate expression using. .

In the above description, the interpolation processing has been described as being performed by interpolation using an approximate expression using a higher-order polynomial. However, in order to reduce the processing, a fixed coefficient as shown in FIG. The resizing for display and resizing in FIG. 4 and the resizing for recording in FIG.
It is preferable to apply to the resizing 1 of. The reason is that, in most cases, the number of pixels of an image in recording and the number of pixels of an image in display are predetermined. As described above, the processing is performed by resizing using a coefficient (fixed coefficient) obtained in advance by an approximate expression using a high-order polynomial, without actually performing an interpolation process using an approximate expression using a high-order polynomial. Can be reduced, which contributes to speeding up and simplification. FIG. 6 shows an example of the interpolation coefficient table in this case. FIG.
In the interpolation coefficient table, the part used only for recording,
Although the part used for both display and recording is shown, the data size differs between the case of recording and the case of display, a part of the interpolation coefficient table is used for display, and all of the table is used. You don't need to use
The portion of the display interpolation coefficient table is shared with the recording interpolation coefficient table. Depending on the data size of the image for display and recording, there may be a portion used only for display, other than the example shown in FIG. 6, and it can be appropriately changed by setting the data size.

FIG. 7 is a flowchart showing a process according to an actual recording image quality mode in recording resizing. In ordinary electronic cameras, SQ (Standard Qua
lity) mode, HQ (High Quality) mode and SHQ
(Super High Quality) mode can be recorded in three modes. Therefore, FIG. 7 shows whether or not it is necessary to perform the above-described interpolation processing when recording in the one-shift mode.

Normally, in an electronic camera, the quality of a captured image is the highest. In FIG. 7, if the image quality mode has not been selected (step S1), the process is terminated as it is, so that no resizing is performed. Next, SQ
If the (Standard Quality) mode is selected (step S2), the number of pixels is smaller than that of the captured image.
An interpolation process is performed (Step S3: Cubi = 1).
If the HQ (High Quality) mode is selected (step S4), the number of pixels is smaller than that of the captured image, as in the case of selecting the SQ, and interpolation processing is performed (step S4).
5: Cubi = 1). And SHQ (Super High Qua
lity) mode is selected (step S4), the number of pixels is the same as that of the captured image, and no interpolation processing is required.
Not performed (Step S6: Cubi = 0). In this case, the interpolation process can be easily and quickly performed by using the interpolation coefficient table as described above.

FIG. 8 is a diagram for explaining the handling of image data recorded in the shared memory. Here, a case in which interpolation is performed by an approximate expression using a third-order polynomial will be described. Normally, when writing data to the memory, the data is written for each data of one block (for example, one block). In this case, the data is written as 4 rows and n columns (for example, when n = 8, 1 block = 32 bytes) as shown in FIG. 8A according to the data amount. Next, when reading the data, as shown in FIG. 8B, the data is sequentially read as four rows and four columns of data, and interpolation is performed using an approximate expression using a two-dimensional cubic polynomial. By doing so, data interpolation can be performed reliably. In this case, it is a matter of course that the data sequence for writing and reading can be appropriately changed according to the order of the approximated polynomial. When a two-dimensional quartic polynomial is used, 5 rows and n columns are used. The data is written as data, and the data of 5 rows and 5 columns is read. Similarly, every time the order increases, two-dimensional m
When the degree polynomial is used, data is written as m + 1 row and n column data, and data of m + 1 row and m + 1 column is read to perform interpolation processing. In this case, it goes without saying that the interpolation coefficient table as described above can be used. In the above description, interpolation of 4 rows and 4 columns has been described. However, the present invention is not limited to this, and as shown in FIG. ) Can be arbitrarily used as representative data, interpolation can be performed by an approximate expression using a one-dimensional cubic polynomial, and data obtained by averaging data of n columns in each of four rows and n columns of data is obtained. It is also possible to perform interpolation using an approximate expression using a one-dimensional cubic polynomial. By doing so, the amount of calculation can be reduced.

It should be noted that the above processing is performed sequentially.
It is a very time-consuming task, and it is not practical to handle it individually. Therefore, time-consuming operations are continuously performed by pipeline processing, so that time can be reduced. FIG. 9 is a schematic block diagram of the pipeline processing. 9, a system controller 70, a pre-processing unit 3, and a built-in memory 30 are connected via a bus 1.
, The image processing unit 5, and the compression / decompression circuit 40 (here, J
PEG compression). The preprocessing unit 3 includes the imaging circuit 13 and the A / D converter 14 in FIG. The image processing unit 5 includes a syscon 70
, And mainly performs processing for reducing or enlarging the image.
In this case, basically, this image processing is a very time-consuming process, and therefore, as shown in the figure, the processing process is divided into multiple stages (in the figure, n stages), and each process is pipelined. By performing the parallel processing by the method, the processing can be shortened.

The present invention is not limited to the above embodiment of the present invention. In the above-described embodiment, an example of only one dimension of a third-order polynomial as an approximation equation has been described. However, it is possible to expand to a fourth-order or higher polynomial, and to perform interpolation using two-dimensional or more multidimensional. It is possible. Furthermore,
If a more accurate approximation formula using an appropriate function (for example, an exponential function) is obtained instead of approximation by a polynomial formula, the approximation formula is used. Giving it is also very effective.

Of course, various modifications can be made without departing from the scope of the present invention.

[0035]

According to the present invention, the following effects can be obtained.

Since high-precision interpolation processing is performed for both display and recording, image quality can be improved in both display and recording. Further, since interpolation is performed under conditions corresponding to the respective resolutions of display and recording, processing efficiency and speed can be improved. Here, since the interpolation conditions are determined for each accuracy or data, efficient processing can be performed.

Further, since dedicated interpolation means is provided for each of display and recording, the processing can be sped up.

In addition, since an interpolation value is calculated from interpolation coefficient information, a complicated circuit is not required, and a high-speed and high-precision interpolation result can be obtained with a simple circuit. In addition, since the interpolation coefficient information is partially shared between the case of displaying and the case of recording,
Saves memory.

Further, since (the original data of) the captured image is shared between the case of displaying and the case of recording, the memory can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a system configuration of an electronic camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing a one-dimensional interpolation model.

FIG. 3 is a block diagram of an interpolation operation circuit 90 according to the present invention.

FIG. 4 is a block diagram showing a flow of a display and recording process according to the present invention.

FIG. 5 is a block diagram showing a modification of FIG. 4;

FIG. 6 is a diagram showing an example of an interpolation coefficient table.

FIG. 7 is a flowchart showing processing according to an actual recording image quality mode in recording resizing.

FIG. 8 is a diagram for describing handling of image data recorded in a shared memory.

FIG. 9 is a schematic block diagram of pipeline processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... photography lens system, 12 ... imaging element, 13 ... imaging circuit, 14 ... A / D converter, 20 ... detachable memory, 21 ... interface (I / F), 22 ... card slot, 30 ... built-in memory, 31 ... Memory area for interpolation processing, 40: compression / expansion circuit, 50: LCD, 51: video memory, 52: video output circuit, 53: external terminal, 70: syscon 73: operation unit, 71: strobe light emitting unit, 61: external Interface (external I / F), 80: power supply unit, 81: camera battery, 90: interpolation arithmetic circuit.

Claims (6)

[Claims] An electronic camera capable of capturing an image of a subject and displaying and recording an image of the captured subject, wherein a display image and a recording image are formed on the basis of the captured image. An electronic camera, comprising: an interpolation unit that forms each of the display image and the recording image by an interpolation process using a polynomial approximation formula. 2. An electronic camera according to claim 1, wherein said interpolating means forms an image under interpolation conditions according to the formed image when forming said display image and said recording image. Electronic camera featuring. 3. The electronic camera according to claim 2, wherein said interpolation condition includes a condition relating to interpolation accuracy or the number of interpolation data. 4. The electronic camera according to claim 1, wherein said interpolating means includes first interpolating means for forming said display image and second interpolating means for forming said recording image. Electronic camera featuring. 5. An electronic camera according to claim 1, wherein said interpolation means stores interpolation coefficient information which is at least partially used in common when forming said display image and said recording image. An electronic camera comprising: means for forming the display image and the recording image using the interpolation coefficient information. 6. The electronic camera according to claim 1, further comprising storage means for storing the captured image data, wherein the means for forming the display image and the means for forming the recording image are provided from the storage means. An electronic camera which reads out captured image data to form the display image and the recording image.