JP2002064702A - Resolution converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resolution converter that can suitably reduce a data capacity of an image, without causing much decrease in the resolution of the image. SOLUTION: The resolution conversion circuit 30 consists of a counter 34a1, that counts pixel data of photographed image data, a conversion rate setting circuit 34a2 that reads a conversion rate corresponding to the count of the counter 34a1 from a conversion rate table 110 that stores the conversion rate in cross-reference with the count, in such a way that the conversion rate becomes smaller starting from the center of the photographed image data going toward the outside, an integer part register 34b that can store integer parts among decision values each consisting of the integer part and a fraction part, a fraction part register 34c that can store fraction parts among the decision values, an adder circuit 34d that adds the conversion rate set by the conversion rate setting circuit 34a2 to the decision values in the registers 34b, 34c, and a discrimination circuit 34e that provides the output of a PXL-ENB signal, on the basis of the result of sum of the adder circuit 34d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for converting a high-resolution image into a low-resolution image.
High-resolution images captured by a device (LCD)
The present invention relates to a resolution conversion device that converts a low-resolution image that can be displayed on a crystal display. More specifically, the present invention relates to a resolution conversion device suitable for reducing the data capacity of an image without significantly reducing the resolution of the image.

[0002]

2. Description of the Related Art In recent years, digital recording type electronic cameras such as digital cameras and digital video cameras have become widespread. The electronic camera includes, for example, a release switch for inputting a photographing timing, a photographing unit including a CCD, an LCD for displaying a photographed image, and an image memory for storing photographed image data captured by the photographing unit. In addition to displaying the captured image from the LCD, the captured image data is captured from the capturing unit at the input timing of the release switch, and the captured captured image data is compressed in a JPEG format or the like and stored in the image memory.

[0003]

However, in recent electronic cameras, since the CCD has a high resolution of 2 to 3 million pixels, even if the captured image data is compressed in a JPEG format or the like, one image can be obtained. The captured image data has a relatively large capacity of 500 [Kbytes]. Here, if the compression ratio is set to a high value, the capacity of one captured image data can be reduced to some extent. However, if the compression ratio is simply set to a high value, the resolution of the captured image data decreases. There's a problem.

Accordingly, the present invention has been made in view of such unresolved problems of the conventional technology, and is intended to reduce the data capacity of an image without significantly reducing the resolution of the image. It is an object of the present invention to provide a suitable resolution converter.

[0005]

The present inventors have made intensive studies and as a result, when taking a picture with an electronic camera, it is usual to place a subject near the center of the viewfinder and take a picture. It has been found that by increasing the resolution at the center where the subject exists in the captured image and lowering the resolution at the outside where the subject does not exist, it is possible to reduce the data capacity without significantly impairing the appearance.

Based on such knowledge, in order to achieve the above object, the resolution conversion apparatus according to the first aspect of the present invention converts a high-resolution image into a low-resolution image by thinning out some of the pixels constituting the image. In the conversion device, the amount of thinning out the high resolution image increases from the center of the high resolution image toward the outside.

With such a configuration, the amount of thinning out of the high-resolution image increases from the center of the high-resolution image toward the outside, and some of the pixels constituting the image are thinned out by such thinning-out amount. Thus, the high resolution image is converted to the low resolution image.

Here, the amount of thinning of the high resolution image may be increased from the center to the outside only in the vertical direction of the high resolution image, or may be increased from the center only in the horizontal direction of the high resolution image. May be increased, or may be increased outward from the center in the radial direction with respect to the center of the high-resolution image. Hereinafter, the same applies to the resolution conversion device according to the second aspect.

Further, according to a second aspect of the present invention, there is provided a resolution conversion apparatus for converting a high resolution image into a low resolution image by thinning out a part of pixels constituting the image. Rate setting means, a determination value storage unit capable of storing a determination value including an integer part and a decimal part,
The vertical or horizontal pixel of the high resolution image is 1
Adding means for adding the conversion rate set by the conversion rate setting means to the determination value of the determination value storage unit each time counting is performed;
Determining means for determining whether to adopt the pixels of the high-resolution image as the pixels of the low-resolution image based on the addition result of the adding means, wherein the determination means includes a result of the addition by the adding means, When the determination value of the determination value storage unit satisfies a predetermined condition, it is configured to determine that a pixel of the high resolution image is adopted as a pixel of the low resolution image, and the conversion rate setting unit is configured to: The conversion rate is set such that the conversion rate becomes smaller from the center of the high-resolution image toward the outside.

With such a configuration, the conversion rate is set by the conversion rate setting means so that the conversion rate decreases from the center of the high-resolution image toward the outside. The conversion rate set by the conversion rate setting means is added to the determination value in the determination value storage unit every time one pixel in the vertical or horizontal direction of the high-resolution image is counted by the adding means. As a result, when the determination value in the determination value storage unit satisfies the predetermined condition, the determination unit determines that the pixel of the high resolution image is adopted as the pixel of the low resolution image.

Here, the conversion rate is the ratio of the number of pixels in the low-resolution image corresponding to that direction to the number of pixels in the vertical or horizontal direction of the high-resolution image, or the ratio is subtracted from "1". Means the ratio In the former case, for example, when there is a carry from the decimal part to the integer part for the determination value of the determination value storage unit, it is determined that the pixels of the high resolution image are adopted as the pixels of the low resolution image, and in the latter case,
For example, when there is no carry from the decimal part to the integer part in the determination value of the determination value storage unit, it may be determined that the pixel of the high resolution image is adopted as the pixel of the low resolution image.

The predetermined condition may be, for example, that the specific digit of the integer part of the judgment value of the judgment value storage unit is a predetermined value, and that the specific digit of the decimal part of the judgment value of the judgment value storage unit is the predetermined value. That the judgment value of the judgment value storage unit has a carry from the decimal part to the integer part, or that the judgment value of the judgment value storage unit has no carry from the decimal part to the integer part. Can be

Further, which pixel of the high-resolution image is adopted as the pixel of the low-resolution image may be determined in any manner as long as it is determined based on the determination result of the determination means. For example, when the determination unit determines that a pixel of the high-resolution image is to be used as a pixel of the low-resolution image, a pixel counted at the time of addition, which has obtained an addition result, is used as a pixel of the low-resolution image. Alternatively, a pixel to be counted at the time of addition following the addition that resulted in the addition may be adopted as a pixel of the low-resolution image.

Further, according to a third aspect of the present invention, in the resolution conversion apparatus according to the second aspect, the conversion rate setting means counts pixels of the high resolution image in a vertical direction or a horizontal direction. Counting means, and storage means for storing the conversion rate in association with the count value of the counting means such that the conversion rate decreases as going outward from the center of the high-resolution image,
Reading means for reading a conversion rate corresponding to the count value of the counting means from the storage means.

With such a configuration, the vertical or horizontal pixels of the high-resolution image are counted by the counting means, and the conversion rate corresponding to the count value of the counting means is read from the storage means by the reading means. .

According to a fourth aspect of the present invention, in the resolution conversion apparatus according to the second aspect, the conversion rate setting means counts pixels in the vertical direction or the horizontal direction of the high resolution image. And a conversion rate calculating means for calculating the conversion rate Y by the following equation (2), where X is the count value of the counting means.

Y = 1−A × (X−B) ² (2) where A and B are constants.

With such a configuration, the vertical or horizontal pixels of the high-resolution image are counted by the counting means, and the conversion rate calculating means sets the count value of the counting means to X by the above equation (2). The conversion rate Y is calculated.

Here, since the conversion rate Y can take a numerical value range of 0 or more and 1 or less from the above definition, in order to obtain a numerical value range of 0 or more, it satisfies A × (X−B) ² ≦ 1. In order to determine the values of the constants A and B as described above, and to obtain a numerical range of 1 or less, the constants A and B are set so that A × (X−B) ² ≧ 0.
The value of B needs to be determined.

In order to set the conversion rate such that the conversion rate decreases from the center of the high-resolution image toward the outside, for example, the constant B is set to 1/2 of the maximum value of the count value of the counting means. do it. According to this setting, when the count value X of the counting means is the minimum value or the maximum value, that is, at the outermost side of the high-resolution image, (X-
B) Since the value of ² becomes maximum, the conversion rate Y takes a minimum value. On the other hand, the count value X of the counting means is 1 / the maximum value.
2, ie, at the center of the high-resolution image, (X−
B) Since the value of ² becomes minimum, the conversion rate Y takes the maximum value.

According to a fifth aspect of the present invention, there is provided a resolution conversion apparatus according to the second or fourth aspect, wherein the determining means determines whether or not the result of the addition by the adding means is a result of the determination. When there is a carry from the decimal part to the integer part in the determination value, it is determined that the pixel of the high resolution image is adopted as the pixel of the low resolution image.

With such a configuration, as a result of the addition by the adding means, when there is a carry from the decimal part to the integer part in the judgment value in the judgment value storage, the judgment means
It is determined that the pixels of the high resolution image are adopted as the pixels of the low resolution image.

In the above, a resolution conversion device for achieving the above object has been proposed. However, the present invention is not limited to this, and it is also possible to provide a storage medium storing the following resolution conversion program for achieving the above object. it can.

This storage medium stores a resolution conversion program for converting a high-resolution image into a low-resolution image by thinning out some of the pixels constituting the image. A conversion rate setting means for setting a conversion rate for a computer having a storable determination value storage unit, and a conversion rate setting means for setting each time one vertical or horizontal pixel of the high-resolution image is counted. Adding means for adding the obtained conversion rate to the determination value in the determination value storage unit, and determining whether to adopt pixels of the high resolution image as pixels of the low resolution image based on the addition result of the addition means. A program for executing a process realized by the determination unit is stored, and the determination unit stores the determination result in the determination value storage unit as a result of the addition by the addition unit. When the predetermined condition is satisfied, it is determined that the pixels of the high-resolution image are adopted as the pixels of the low-resolution image, and the conversion rate setting unit goes outward from the center of the high-resolution image. A computer-readable storage medium configured to set the conversion rate such that the conversion rate decreases as the conversion rate decreases.

With such a configuration, the program stored in the storage medium is read by the computer,
When the computer executes the program in accordance with the read program, an operation equivalent to that of the resolution converter according to the second aspect is obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 to 5 are diagrams showing a first embodiment of a resolution conversion device according to the present invention.

In this embodiment, as shown in FIG. 1, a resolution conversion device according to the present invention converts a high-resolution image captured by a CCD 14 into a low-resolution image in a CCD camera 100 and stores it in a main memory 42. This applies to cases where

First, a CCD camera 10 to which the present invention is applied
0 will be described with reference to FIG. FIG. 1 shows the CC
FIG. 2 is a block diagram showing an internal configuration of the D camera 100.

As shown in FIG. 1, the CCD camera 100 includes a photographing unit 10 for taking a photographed image as data, and a conversion unit 20 for converting a high-resolution image taken by the photographing unit 10 into a low-resolution image that can be displayed on the LCD 52. And the conversion unit 2
And a display unit 50 for displaying the low-resolution image converted by the zero.

The photographing unit 10 includes an optical lens 12 and a CCD.
And a CCD control circuit 16 for controlling the CCD 14.

The CCD 14 has a plurality of pixels, and photoelectrically converts an optical image of a subject formed on each pixel into an image signal (electric signal) via the optical lens 12 disposed at the preceding stage. .

Although not shown, the CCD processing circuit 16 has a C
CD drive circuit, A / D conversion circuit, and image processing unit (DS
P: Digital Signal Processor). CC
The D drive circuit supplies vertical and horizontal drive pulses to the CCD 14, and outputs an image signal photoelectrically converted by the CCD 14 to the A / D conversion circuit. The A / D conversion circuit amplifies the image signal to a predetermined level, samples at a predetermined timing, and outputs the sampled digital image data to the DSP. The image processing unit generates captured image data from the digital image data, and outputs the generated captured image data to the conversion unit 20. Note that the image processing unit performs image processing at a speed at which the CCD 14 is driven, and similarly outputs captured image data to the conversion unit 20 at a speed at which the CCD 14 is driven.

The display section 50 includes a timing generation circuit 54 for generating a timing signal indicating the timing of displaying an image on the LCD 52, and an LCD 52 for displaying an image in synchronization with the timing signal generated by the timing generation circuit 54. ing.

The conversion unit 20 includes a resolution conversion circuit 30 that converts captured image data, which is a high-resolution image captured by the imaging unit 10, into storage image data, which is a low-resolution image, and a high-resolution image captured by the imaging unit 10. A resolution conversion circuit 39 for converting captured image data, which is a low resolution image that can be displayed by the LCD 52, to a display image data, and a CP for calculating and controlling the entire system based on a control program.
U40 and main memory 4 for storing image data
2 and an image data writing circuit 44 for writing the storage image data converted by the resolution conversion circuit 30 into the main memory 42.
An image data writing circuit 45 for writing the display image data converted by the resolution conversion circuit 39 into the main memory 42;
The LCD 5 based on the display image data in the main memory 42
2 includes a display control circuit 46 for controlling display of an image and an access control circuit 48 for controlling access to the main memory 42. In addition, although not shown, a predetermined area has a ROM in which a control program of the CPU 40 is stored in advance, and the CPU 40 activates a predetermined program stored in the predetermined area of the ROM and operates according to the program. It has become.

The main memory 42 is composed of a RAM for storing data read from a ROM or the like and a calculation result required in the calculation process of the CPU 40. The RAM is used as a specific area for storing display image data. VRA
M43. The VRAM 43 includes a CPU 40,
The image data writing circuit 45 and the display control circuit 46 can access each independently.

The resolution conversion circuit 39 determines the conversion rate (the ratio of the number of pixels in the low-resolution image corresponding to the direction to the number of pixels in the vertical or horizontal direction of the high-resolution image) composed of an integer part and a decimal part. A conversion rate register capable of storing, a determination value register capable of storing a determination value including an integer part and a decimal part, and a determination value of the determination value register each time vertical or horizontal pixel data of captured image data is counted An addition circuit that adds the conversion rate of the conversion rate register to the conversion rate register, and a determination circuit that determines whether to use the pixel data of the captured image data as the display image data based on the addition result of the addition circuit. If the result of the addition by the adder circuit indicates that there is a carry from the decimal part to the integer part in the judgment value of the judgment value register, the pixel of the captured image data It is adapted to determine to adopt the over data as display image data. In the conversion ratio register, the ratio of the number of pixels in the display image data corresponding to that direction to the number of pixels in the vertical or horizontal direction of the captured image data is set.

When a release request (not shown) is depressed and the CPU 40 issues a capture request when the release switch (not shown) is pressed, the image data writing circuit 44 converts the captured image into a predetermined area of the main memory 42 at high resolution (an area other than the VRAM 43). , The storage image data converted by the resolution conversion circuit 30 is stored in the predetermined area of the main memory 42.

The image data writing circuit 45 writes the display image data converted by the resolution conversion circuit 39 into the VRAM 43 in order to display the photographed image on the LCD 52 at a low resolution.

The display control circuit 46 synchronizes with the timing signal generated by the timing generation circuit 54 to
3 is sequentially read from the head address, and the read display image data is converted into an image signal and output to the LCD 52.

When a plurality of accesses from the CPU 40, the image data writing circuits 44 and 45 or the display control circuit 46 to the main memory 42 are made at the same time, the access control circuit 48 permits one of those accesses. The other memory is kept waiting until the permitted access is completed, so that only one access to the main memory 42 is always permitted. In addition, not only when there is a plurality of accesses at the same time, but also when there is another access while accessing the main memory 42,
It works similarly.

Next, the configuration of the resolution conversion circuit 30 will be described in detail with reference to FIGS. 2 and 3 are block diagrams showing the circuit configuration of the resolution conversion circuit 30.

As shown in FIG. 2, the resolution conversion circuit 30 sequentially inputs pixel data indicating the color of each pixel constituting the photographed image as photographed image data, and outputs the first pixel in the vertical and horizontal directions of the CCD 14. (A VSYNC _in signal indicating the timing at which the upper left pixel of the CCD 14 is input), an HSYNC _in signal indicating a timing at which the first pixel in the horizontal direction of the CCD 14 (the left pixel of each line of the CCD 14) is input, and each pixel data And a PXL_CLK signal indicating the timing at which the is input. Further, it outputs the pixel data indicating a color of each pixel configuring the image as stored image data sequentially, the VSYNC _out signal obtained by delaying the VSYNC _in signal, obtained by delaying the HSYNC _in signal HSYNC
_{An out} signal and a PXL_ENB signal indicating whether or not pixel data output as storage image data are valid are output.

As shown in FIG. 3, the resolution conversion circuit 30 controls the display address calculation circuit 34 in synchronization with the HSYNC _in signal and the PXL_CLK signal, and as the storage image data of the captured image data. It comprises a display address calculation circuit 34 for calculating the address of the adopted pixel data in the photographed image data, and a data latch circuit 36 for latching pixel data employed as storage image data in the photographed image data.

The synchronization control circuit 32 outputs the VSYNC _in signal, HSYNC
_{The in} signal and the PXL_CLK signal are input. In addition, the HSYNC _in signal is output as a RESET signal, and VSYN in accordance with the output timing of the storage image data.
A VSYNC _out signal obtained by delaying the C _in signal by a predetermined time and an HSYNC _out signal obtained by delaying the HSYNC _in signal by a predetermined time _in accordance with the output timing of the image data for storage are output.

The display address calculation circuit 34 receives the PXL_CLK signal and the RESET signal, and outputs a PXL_ENB signal.

The data latch circuit 34 latches captured image data at the input timing of the PXL_ENB signal. As a result, the pixel data used as the storage image data among the captured image data is latched.

Next, the configuration of the display address calculation circuit 34 will be described in detail with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of the display address calculation circuit 34.

The display address calculating circuit 34, as shown in FIG. 4, the conversion rate of reading the counter 34a ₁ for counting the pixel data of the captured image data, the conversion ratio corresponding to the count value of the counter 34a ₁ from the conversion rate table a setting circuit 34a _2, the integer part and an integer part register 34b capable of storing integer part of the decision value consisting of the fractional part, retractable fractional part register 34c a fractional portion of the determined value
When adder circuit 34d for adding the conversion rate set in the conversion rate setting circuit 34a ₂ register 34b, the determination value 34c
And a determination circuit 34e that outputs a PXL_ENB signal based on the addition result of the addition circuit 34d.

The counter 34a _1, each time entering the PXL_CLK signal, held to the count value is added to "1" is output to the conversion rate setting circuit 34a _2, at the input timing of the RESET signal, and holds Reset the count value.

The conversion rate setting circuit 34a _2, as shown in FIG. 5, stores from the center of the captured image data in association with the count value of the counter 34a ₁ the conversion rate so that the conversion rate decreases toward the outside Conversion rate table 110
Has, when inputting the count value from the counter 34a ₁ reads out the conversion ratio corresponding to the count value input from the conversion table 110 and outputs to the adding circuit 34d. FIG. 5 is a diagram showing a data structure of the conversion rate table 110.

The conversion rate table 110 registers one record for each count value. Each record includes a field 112 for registering a count value and a field 114 for registering a conversion rate. I have. The count value and the conversion rate registered in the conversion rate table 110 have the following relationship. That is, assuming that the count value is X, the conversion rate Y can be calculated by the following equation (3). In the following expression (3), when the maximum value of the count value is “1999”, the constant A becomes, for example, “1/10000000” because the conversion rate decreases from the center of the captured image data toward the outside. ,
The constant B is, for example, "1000".

Y = 1−A × (X−B) ² (3) In the example shown in FIG. 5, in the record at the top of the figure, “0” as the count value
Is registered as the conversion rate. In the lowermost record in the figure, “1999” is registered in the field 112 as the count value, and “0.001999” is registered in the field 114 as the conversion rate.

The adder circuit 34d, each time entering the PXL_CLK signal, adds the integer part and conversion rate set in the conversion rate setting circuit 34a ₂ to the determination value consisting of the fractional part of the fractional part register 34c of the integer part register 34b In addition, the integer part of the addition result is output to the integer part register 34b, and the decimal part is output to the decimal part register 34c.

The integer part register 34b resets the held content at the input timing of the RESET signal, and resets the PXL_
The addition result of the addition circuit 34d is latched at the input timing of the CLK signal.

The fraction register 34c resets the held content at the input timing of the RESET signal, and resets the PXL_
The addition result of the addition circuit 34d is latched at the input timing of the CLK signal.

The decision circuit 34e outputs a PXL_ENB signal when the value of the integer register 34b changes as a result of the addition by the addition circuit 34d. That is, when there is a carry from the decimal part to the integer part in the determination value, it is determined that the pixel data of the captured image data is adopted as the storage image data.

The synchronization control circuit 32, the display address calculation circuit 34, and the data latch circuit 34 are circuits for performing resolution conversion on the horizontal pixels of the captured image data. A circuit for converting the resolution of the image data can be similarly configured.

Next, the operation of the first embodiment will be described.

The resolution of the CCD 14 is 2000 × 1500.
The case where the pixel is used will be described as an example. In this case, the number of pixels in the horizontal direction of the captured image data is “2000”, and the number of pixels in the vertical direction of the captured image data is “150”.
0 ".

First, when a release switch (not shown) is depressed, the CPU 40 outputs a capture request to the image data writing circuit 45. In the image data writing circuit 45, when there is a capture request, a captured image is captured as data by the capturing unit 10, and the captured captured image data is output to the resolution conversion circuit 30.

[0061] In the resolution conversion circuit 30, the captured image data is input, for each pixel of a first line from the top of the CCD 14, the counter 34a _1, pixel data of the photographed image data is counted, conversion rate setting circuit the 34a _2, conversion ratio corresponding to the count value of the counter 34a ₁ is read from the conversion table 110, is output to the adding circuit 34d. At this time, the read conversion rate decreases from the center of the captured image data toward the outside. For example, when the count value of the counter 34a ₁ is the minimum value of "0" or the maximum value "1999", that is, the outermost of the captured image data, conversion is the minimum value "0". On the other hand, when the counter 34a ₁ the count value is "1000", that is, the center of the captured image data, conversion ratio Y is the maximum value "1".

In the adder circuit 34d, the pixel data is set to 1
Each counting, conversion of the conversion rate setting circuit 34a ₂ is register 34b, is added to the determination value 34c.
As a result, when there is a carry from the decimal part to the integer part, the determination circuit 34e outputs the PXL_ENB signal. Next, the captured image data is latched by the data latch circuit 36 at the input timing of the PXL_ENB signal. As a result, for each pixel on the first line from the top of the CCD 14, pixel data to be employed as storage image data among the captured image data is latched.

A series of these processes is performed for each line of the CCD 14. Here, the case where the resolution conversion is performed on the pixels in the horizontal direction of the captured image data has been described, but the case where the resolution conversion is performed on the pixels in the vertical direction of the captured image data also operates in the same manner. .

On the other hand, when image data for storage is input to the image data writing circuit 44, the image data for storage converted by the resolution conversion circuit 30 is written in the predetermined area of the main memory 42. When writing to the main memory 42, the storage image data is further compressed in a JPEG format or the like.

When a release switch (not shown) is not pressed, the captured image is displayed at a low resolution.
In order to display on D52, the following operation is performed.

A photographic image of 2000 × 1500 pixels is converted into 40
The case of converting to a display image of 0 × 375 pixels will be described as an example. In this case, the ratio of the number of pixels corresponding to the direction of the display image to the number of pixels in the vertical direction or the horizontal direction of the captured image is "0.2". 2 ”is set.

First, in the photographing unit 10, a photographed image is captured as data, and the captured captured image data is output to the resolution conversion circuit 39.

When the captured image data is input to the resolution conversion circuit 39, the pixel data of each pixel on the first line from the top of the CCD 14 is reduced by the addition circuit to 1 pixel data.
Each time counting is performed, the conversion rate “0.2” of the conversion rate register is added to the determination value of the register. As a result, when there is a carry from the decimal part to the integer part, the determination circuit outputs the PXL_ENB signal. Next, the captured image data is latched by the data latch circuit 36 at the input timing of the PXL_ENB signal. Thereby, the CCD 14
For each pixel on the first line from above, pixel data to be adopted as storage image data among the captured image data is latched.

A series of these processes is performed for each line of the CCD 14. Here, the case where the resolution conversion is performed on the pixels in the horizontal direction of the captured image data has been described, but the case where the resolution conversion is performed on the pixels in the vertical direction of the captured image data also operates in the same manner. .

On the other hand, when the display image data is input to the image data writing circuit 45, the display image data converted by the resolution conversion circuit 39 is written to the VRAM 43.
When the display image data is written to the VRAM 43, the display image data of the VRAM 43 is sequentially read from the head address by the display control circuit 46 in synchronization with the timing signal from the timing generation circuit 54, and the read display image data is read out. Is converted into an image signal and output to the LCD 52. As a result, on the LCD 52, the captured image data captured by the capturing unit 10 is converted into a displayable low-resolution image and displayed.

[0071] Thus, in the present embodiment, the resolution conversion circuit 30 includes a counter 34a ₁ for counting the pixel data of the captured image data, as the conversion rate as from the center of the photographed image data toward the outside becomes small a conversion factor setting circuit 34a ₂ for reading the conversion ratio corresponding from the conversion rate table 110 that the conversion rate and stored in association with the count value of the count value of the counter 34a _1, the integer of the decision value consisting of an integer part and a fractional part and integer unit register 34b capable of storing parts, and can be stored fractional part register 34c a fractional part of the decision value, adds the conversion rate set in the conversion rate setting circuit 34a ₂ to the determination value of the register 34b, 34c adds Circuit 34d, and a determination circuit 34e that outputs a PXL_ENB signal based on the addition result of the addition circuit 34d. As a result of the addition performed by the arithmetic circuit 34d, when there is a carry from the decimal part to the integer part in the determination values of the registers 34b and 34c, it is determined that the pixel data of the captured image data is used as the storage image data. .

As a result, in the captured image, the resolution at the center where the subject exists is high, and the resolution outside the subject is low is low. Therefore, the data capacity of the storage image data is not significantly impaired. Can be reduced. Therefore, the data capacity of the image can be relatively reduced without significantly reducing the resolution of the image as compared with the related art.

[0073] Further, in this embodiment, the center from the count value from the conversion table 110 which stores the counter 34a ₁ the conversion rate so that the conversion rate decreases in correspondence with the count value toward the outside of the photographic image data The conversion rate corresponding to is read.

As a result, the processing load on the resolution conversion circuit 30 can be reduced as compared with the case where the conversion rate is calculated by calculation.

Further, in the present embodiment, the judgment circuit 34
e is the result of the addition by the addition circuit 34d,
When there is a carry from the decimal part to the integer part in the determination values of b and 34c, it is determined that the pixel data of the captured image data is adopted as the storage image data.

This makes it relatively easy to determine whether to use the pixel data of the photographed image data as the storage image data.

In the first embodiment, the counter 34a ₁ and the conversion rate setting circuit 34a ₂ correspond to the conversion rate setting means according to claim 2 or 3, and the integer part register 3
The 4b and b fraction register 34c may be configured as described in claim 2 or 5.
The adding circuit 34d corresponds to the adding means according to claim 2 or 5, and the determining circuit 34e corresponds to the adding means.
Corresponds to the determination means of claim 2 or 5.
The counter 34a ₁ corresponds to the counting means according to claim 3, the conversion table 110 corresponds to the storage means according to claim 3, wherein the conversion rate setting circuit 34a ₂ is claim 3 reading means according It corresponds to.

Next, a second embodiment of the present invention will be described with reference to the drawings. 6 and 7 are diagrams showing a second embodiment of the resolution conversion device according to the present invention.
Hereinafter, only the portions different from the first embodiment will be described, and the overlapping portions will be denoted by the same reference numerals and description thereof will be omitted.

In the present embodiment, as shown in FIG. 1, a resolution conversion device according to the present invention converts a high-resolution image captured by a CCD 14 into a low-resolution image in a CCD camera 100 and stores it in a main memory 42. This applies to cases where The difference from the first embodiment is that the conversion rate table 110 is not used and the counter 34a is used.
_The point is that the conversion rate Y is calculated from the count value of _{1 by} a calculation formula.

First, the configuration of the display address calculation circuit 34 will be described in detail with reference to FIG. FIG. 6 is a block diagram showing a circuit configuration of the display address calculation circuit 34.

[0081] display address calculating circuit 34, as shown in FIG. 6, the counter and 34a _1, conversion ratio calculating circuit 34a for calculating a conversion rate based on the count value of the counter 34a _1
3 , an integer part register 34b, and a decimal part register 34c
When adder circuit 34d for adding the calculated conversion rate conversion ratio calculating circuit 34a ₃ register 34b, the determination value 34c
And a determination circuit 34e.

The conversion rate calculating circuit 34a ₃ includes a counter 34
When the count value of a ₁ is X, the conversion rate Y is calculated by the above equation (3).
Is calculated. Count value X and conversion rate Y
As shown in FIG. 7, when the count value X which is the outermost part of the captured image data is the maximum value or the minimum value so that the conversion rate Y becomes smaller from the center of the captured image data to the outside as shown in FIG. Is that the conversion rate Y takes the minimum value and the count value X, which is the center of the captured image data, is 1 / the maximum value.
In the case of 2, the conversion rate Y takes the maximum value. FIG. 7 is a graph showing a change in the change rate Y with respect to a change in the count value X.

The synchronization control circuit 32, the display address calculation circuit 34, and the data latch circuit 34 are circuits for performing resolution conversion on the horizontal pixels of the captured image data. A circuit for converting the resolution of the image data can be similarly configured.

Next, the operation of the second embodiment will be described.

The resolution of the CCD 14 is 2000 × 1500
The case where the pixel is used will be described as an example. In this case, the number of pixels in the horizontal direction of the captured image data is “2000”, and the number of pixels in the vertical direction of the captured image data is “150”.
0 ".

First, when a release switch (not shown) is depressed, a capture request is output by the CPU 40 to the image data writing circuit 44. In the image data writing circuit 44, when there is a capture request, the captured image is captured as data by the capturing unit 10, and the captured captured image data is output to the resolution conversion circuit 30.

[0087] In the resolution conversion circuit 30, the captured image data is input, for each pixel of a first line from the top of the CCD 14, the counter 34a _1, pixel data of the photographed image data is counted, the conversion rate calculating circuit the 34a _3, the conversion ratio Y by the above equation (3) is calculated based on the count value of the counter 34a _1, the adder circuit 34
d. At this time, the calculated conversion rate Y decreases from the center of the captured image data toward the outside. For example, when the count value of the counter 34a ₁ is the minimum value of "0" or the maximum value "1999", that is, the outermost of the captured image data, conversion is the minimum value "0". On the other hand, the count value of the counter 34a ₁ is "100
When the value is "0", that is, at the center of the captured image data, the conversion rate Y takes the maximum value "1".

In the adder circuit 34d, the pixel data is set to 1
Each counting, conversion rate Y from the conversion rate calculating circuit 34a ₃ is register 34b, is added to the determination value 34c. As a result, when there is a carry from the decimal part to the integer part, the determination circuit 34e outputs the PXL_ENB signal. Next, PXL_ENB
The captured image data is latched at the signal input timing. As a result, for each pixel on the first line from the top of the CCD 14, pixel data to be employed as storage image data among the captured image data is latched.

Then, a series of these processes are performed for each line of the CCD 14. Here, the case where the resolution conversion is performed on the pixels in the horizontal direction of the captured image data has been described, but the case where the resolution conversion is performed on the pixels in the vertical direction of the captured image data also operates in the same manner. .

On the other hand, when the image data for storage is input to the image data writing circuit 44, the image data for storage converted by the resolution conversion circuit 30 is written in the predetermined area of the main memory 42. The image data for storage written in the main memory 42 is further processed by the CPU 40 in JPE.
It is compressed in G format or the like.

Note that, during non-shooting when the release switch (not shown) is not depressed, the operation is the same as in the first embodiment.

As described above, in the present embodiment, the resolution conversion circuit 30 converts the pixel data of the photographed image data into the counter 34a ₁ based on the count value of the counter 34a _{1 by} the above equation (3). a conversion rate calculation circuit 34a ₃ for calculating the rate, the integer part and can be stored integer part of the integer part of the decision value consisting of the fractional part register 34
b and a fractional part register 34c can store the fractional part of the decision value, the register 34b the calculated conversion rate conversion ratio calculating circuit 34a _3, the adder circuit adds to the determination value 34c 3
4d and PXL_ENB based on the addition result of the addition circuit 34d.
A decision circuit 34e for outputting a signal;
e is the result of the addition by the addition circuit 34d,
When there is a carry from the decimal part to the integer part in the determination values of b and 34c, it is determined that the pixel data of the captured image data is adopted as the storage image data.

As a result, in the captured image, the resolution at the center where the subject exists is high, and the resolution outside the subject is not high is low. Therefore, the data capacity of the storage image data is not significantly impaired. Can be reduced. Therefore, the data capacity of the image can be relatively reduced without significantly reducing the resolution of the image as compared with the related art.

Further, in this embodiment, the counter 34
and to calculate the conversion ratio by the above equation (3) based on the count value of a _1.

As a result, the data capacity of the resolution conversion circuit 30 can be reduced as compared with the case where the conversion rate is stored in a table and read out, as in the first embodiment.

Further, in the present embodiment, the judgment circuit 34
e is the result of the addition by the addition circuit 34d,
When there is a carry from the decimal part to the integer part in the determination values of b and 34c, it is determined that the pixel data of the captured image data is adopted as the storage image data.

Thus, it is relatively easy to determine whether or not to use the pixel data of the photographed image data as the storage image data.

In the second embodiment, the counter 34a ₁ and the conversion rate setting circuit 34a ₂ correspond to the conversion rate setting means according to claim 2 or 4, and the integer part register 3
The 4b and b fraction register 34c may be configured as described in claim 2 or 5.
The adding circuit 34d corresponds to the adding means according to claim 2 or 5, and the determining circuit 34e corresponds to the adding means.
Corresponds to the determination means of claim 2 or 5.
The counter 34a ₁ corresponds to the counting means according to claim 4, wherein the conversion rate calculating circuit 34a ₃ corresponds to the conversion rate calculating unit according to claim 4, wherein.

In the first and second embodiments, when the result of the addition by the adder circuit 34d is that there is a carry from the decimal part to the integer part, the determination circuit 34e takes a photograph. The pixel data of the image data is determined to be used as the storage image data. However, the present invention is not limited to this. If the determination value does not carry from the decimal part to the integer part, the pixel data of the photographed image data is used. May be determined to be used as storage image data. In this case, a value obtained by subtracting the above change rate from “1” is stored in the change rate register 34a.

In the first and second embodiments, the resolution conversion circuit 30 is replaced with the synchronization control circuit 32,
Display address calculation circuit 34 and data latch circuit 34
However, the present invention is not limited to this, and the function of the resolution conversion circuit 30 may be realized by processing executed by the CPU 40. In this case, a program for realizing the functions of the synchronization control circuit 32, the display address calculation circuit 34, and the data latch circuit 34 is stored in the ROM,
The CPU 40 activates a predetermined program stored in a predetermined area of the ROM, and executes these processes according to the program. The present invention is not limited to this, and the synchronization control circuit 32, the display address calculation circuit 3
In executing the processing for realizing the functions of the data latch circuit 4 and the data latch circuit 34, the main memory 42 may read and execute the program from a recording medium on which a program indicating these procedures is recorded.

Here, the recording medium includes a semiconductor storage medium such as a RAM and a ROM, a magnetic storage type storage medium such as an FD and an HD, an optical reading type storage medium such as a CD, CDV, LD, and DVD, and a storage medium such as an MO. It is a magnetic storage type / optical readout type storage medium, and includes any storage medium that can be read by a computer irrespective of an electronic, magnetic, optical or other reading method.

In the first and second embodiments, the LCD 52 displays a high-resolution image captured by the CCD 14 in the CCD camera 100 as shown in FIG. Although the present invention has been applied to the case where the image is converted into a possible low-resolution image, the present invention is not limited to this, and can be applied to other cases without departing from the gist of the present invention.

[0103]

As described above, according to the resolution conversion apparatus according to the first to fifth aspects of the present invention, the data resolution of the image can be compared with that of the conventional one without significantly lowering the resolution of the image. This has the effect of achieving a significant reduction.

Further, according to the resolution conversion apparatus of the third aspect of the present invention, an effect is obtained that the processing load on the apparatus can be reduced as compared with the case where the conversion rate is calculated by calculation. .

Further, according to the resolution conversion device of the fourth aspect of the present invention, the data capacity of the device can be reduced as compared with the case where the conversion ratio is stored and read out in a table or the like. Is also obtained.

Further, according to the resolution conversion apparatus of the fifth aspect of the present invention, it is possible to relatively easily determine whether or not to adopt the pixels of the high resolution image as the pixels of the low resolution image. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram showing an internal configuration of a CCD camera 100.

FIG. 2 is a block diagram showing a circuit configuration of a resolution conversion circuit 30.

FIG. 3 is a block diagram illustrating a circuit configuration of a resolution conversion circuit 30.

4 is a block diagram illustrating a circuit configuration of a display address calculation circuit 34. FIG.

FIG. 5 is a diagram showing a data structure of a conversion rate table 110.

6 is a block diagram showing a circuit configuration of a display address calculation circuit 34. FIG.

FIG. 7 is a graph showing a change in a change rate Y with respect to a change in a count value X.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 CCD camera 10 shooting unit 14 CCD 16 CCD control circuit 20 conversion unit 30 resolution conversion circuit 32 synchronization control circuit 34 display address calculation circuit 34 a ₁ counter 34 a ₂ conversion rate setting circuit 34 a ₃ conversion rate calculation circuit 34 b integer part register 34 c decimal part Register 34d Addition circuit 34e Judgment circuit 36 Data latch circuit 40 CPU 42 Main memory 44, 45 Image data writing circuit 46 Display control circuit 50 Display section 52 LCD

Claims (5)

[Claims] 1. An apparatus for converting a high-resolution image into a low-resolution image by thinning out a part of pixels constituting the image, wherein the amount of thinning of the high-resolution image increases from the center to the outside of the high-resolution image. A resolution conversion device characterized in that the resolution conversion device performs 2. An apparatus for converting a high-resolution image into a low-resolution image by thinning out a part of pixels constituting an image, comprising: a conversion rate setting means for setting a conversion rate; And a conversion rate set by the conversion rate setting means each time one pixel in the vertical or horizontal direction of the high-resolution image is counted, to the determination value in the determination value storage section. An addition unit; and a determination unit configured to determine whether to adopt a pixel of the high-resolution image as a pixel of the low-resolution image based on an addition result of the addition unit. As a result of the addition, when the determination value of the determination value storage unit satisfies a predetermined condition, it is determined to adopt the pixels of the high resolution image as the pixels of the low resolution image, The resolution conversion device, wherein the conversion rate setting means sets the conversion rate such that the conversion rate decreases from the center of the high-resolution image toward the outside. 3. The high-resolution image according to claim 2, wherein the conversion rate setting means includes a counting means for counting pixels in a vertical direction or a horizontal direction of the high-resolution image, and the conversion rate as moving outward from a center of the high-resolution image. Storage means for storing the conversion rate in association with the count value of the counting means so that the conversion rate becomes smaller, and reading means for reading out the conversion rate corresponding to the count value of the counting means from the storage means. Resolution conversion device. 4. The conversion rate setting unit according to claim 2, wherein the conversion ratio setting unit counts a pixel in the vertical direction or the horizontal direction of the high-resolution image, and X represents a count value of the counting unit. And a conversion rate calculating means for calculating the conversion rate Y according to the following. Y = 1−A × (X−B) ² (1) where A and B are constants. 5. The method according to claim 2, wherein the determination unit determines that there is a carry from a decimal part to an integer part in the determination value of the determination value storage unit as a result of the addition by the addition unit. Is configured to determine that pixels of the high-resolution image are adopted as pixels of the low-resolution image.