JP2002359773A - Image input output device, image conversion method and image conversion program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display an image pickup object with a prescribed grey level number even when the lightness of the imaging object is changed. SOLUTION: When an object H is picked up so as to have a luminance coincident with a target luminance AK, a tone curve TC 2 wherein a gradient of a proper exposure range of the object H is steep and the gradient of other ranges is gentle is used and gradation processing is applied to image data GD, and when the luminance AK is changed, the tone curve TC 2 is displaced in parallel so that the object luminance AK comes to the middle of the steep part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image input / output device,
Image conversion method and image conversion program, in particular,
It is suitable for application when image data is transferred between devices having different dynamic ranges.

[0002]

2. Description of the Related Art In a conventional image input / output device such as a video camera and a videophone, a camera for capturing an image and
A display unit for displaying an image is provided, and some display units can display an image captured by a camera. FIG.
FIG. 11 is a block diagram illustrating a schematic configuration of a conventional image input / output device. In FIG. 8, the image input / output device is provided with an image sensor 1 for capturing an image of a subject H and a display device 8 for displaying an image and the like. An exposure control unit 2 for performing the operation is provided. Here, the exposure control unit 2 is provided with a photometry logic 2a and a timing & sensor control unit 2b, and the output data SD output from the image sensor 1 is provided.
Is input to the image processing logic 4 and the photometry logic 2a.

In the image processing logic 4, output data SD
Is performed and output to the tone curve section 6 as image data GD. In the tone curve section 6, gradation processing of the image data GD is performed.
The data is converted into display data HD suitable for display on the display device 8. For example, assuming that image data GD of each of RGB 8 bits is output from the image sensor 1 side and display data HD of each of 6 bits of RGB is input to the display device 8.
The tone curve section 6 converts the image data GD of 256 gradations output from the image sensor 1 side into the display data HD of 64 gradations and outputs them to the display device 8 side. As a method of converting the data of 256 gradations to 64 gradations, there is a method of thinning out each of the LSB side 2 bits from the RGB 8 bit image data GD output from the image sensor 1 side.

If an image input to the display device 8 is known in advance, a tone curve which can optimally represent the image is stored in advance, and by referring to the tone curve, the image data GD of the image data GD is stored. There is also a method of compressing gradation. Display data HD output from tone curve section 6
Is output to the display interface unit 7 in synchronization with the synchronization signal DS1 from the image processing logic 4, and the display interface unit 7 stores the display data HD from the tone curve unit 6 via the display control unit 7a in the video memory. 7b.

The display data HD stored in the video memory 7b is input to the display & synchronization signal generator 8a in synchronization with the synchronization signal DS2 output from the display & synchronization signal generator 8a. Is displayed. Here, when a liquid crystal display device is used as the display device 8, by turning on the backlight 8b, the brightness of the liquid crystal display device can be improved.

On the other hand, the photometry logic 2a performs photometry based on output data SD from the image sensor 1, and
The photometric evaluation value SR is output to the timing & sensor control unit 2b. The timing & sensor control unit 2b also receives the target luminance value AK and the drive mode K from the digital system 9.
M is input, and the timing & sensor control unit 2b controls the shutter speed SP and the gain value GC so that the photometric evaluation value SR matches the target luminance value AK, and inputs the shutter speed SP to the timing generator 3. At the same time, the gain value GC is input to the image sensor 1. Then, the timing generator 3 drives the image sensor 1 at the shutter speed SP output from the timing & sensor control unit 2b, and the image sensor 1 outputs the gain value G output from the timing & sensor control unit 2b.
By amplifying the output data SD by C, the photometric evaluation value SR is made to coincide with the target luminance value AK.

As a result, the exposure of the image sensor 1 can be controlled, and the luminance value of the output data SD from the image sensor 1 can be maintained at an appropriate exposure value without depending on the brightness B of the subject H. Can be.

[0008]

However, in order to make the dynamic range of the image data GD output from the image sensor 1 correspond to the dynamic range of the display device 8, the image data GD output from the image sensor 1 is changed. In the method of uniformly lowering the number of gradations of the GD, since the gradation of an area imaged with the target exposure also decreases, the area is displayed in a mosaic shape, and among the images imaged by the image sensor 1, the user However, there is a problem that a target portion is not displayed clearly.

On the other hand, the image data G
In the method of performing the gradation processing of D, since the tone curve is fixed regardless of the brightness B of the subject H, an image captured by the image sensor 1 is displayed on the display device 8 depending on the brightness B of the subject H. When displayed, it may be crushed black, and there is a problem that the displayed image is greatly deteriorated.
Therefore, an object of the present invention is to provide an image input / output device, an image conversion method, and an image conversion program capable of displaying an imaging target with a predetermined number of gradations even when the brightness of the imaging target changes. That is.

[0010]

According to an embodiment of the present invention, there is provided an image input / output apparatus for acquiring image data, comprising: an image data acquiring unit for acquiring image data; And a gradation control means for controlling a gradation of the image data.

Accordingly, even when the dynamic range for displaying the image data is narrower than the dynamic range of the image data, the image data is displayed while maintaining the gradation of the region imaged with the target exposure. Therefore, even when the dynamic range at the time of display is narrower than that at the time of imaging, it is possible to reduce discomfort when viewing the image.

Further, according to the image input / output device of the second aspect, the gradation control means may control the gradation of the image data so that a target exposure area of the image data is expressed in gradation on a display means. The key is controlled. Note that the target exposure area is an area in a screen where a subject is likely to be present in a captured image, and may be fixed or variable. In this area, the exposure is controlled so as to match the target luminance value. Also, the target luminance value refers to a value indicating where the luminance of the target exposure area is to be matched,
It can be given as default or by external setting.

Thus, no matter what image is displayed, the gradation of the target exposure area in which the subject is displayed is maintained by using the exposure control function already provided at the time of image capturing. It is possible to reduce the gradation of a portion outside the target exposure area in a background including the above. For this reason, it is possible to display a portion targeted by the user by making full use of the dynamic range of the display unit without performing gradation processing on the display unit side. Can be reduced with a simple configuration when looking at the image.

According to a third aspect of the present invention, when the brightness of the image data does not reach the target luminance value, the gradation control means displays the photometric evaluation area of the image data. It is characterized in that the gradation of the imaging data is controlled so that the gradation is expressed above. Here, the photometric evaluation area may be considered to be the same as the target exposure area, and is an area in the screen where the subject may exist, and the brightness of the imaging data is evaluated in this area. The brightness of the image data refers to the brightness of the photometry evaluation area, and the method of calculating the brightness of the photometry evaluation area and the brightness of the photometry evaluation area can be designated as a default or by an external setting.

Thus, even when the subject is extremely dark and the subject is not properly exposed, the subject can be displayed on the display means while maintaining the gradation at the time of imaging, and the brightness of the subject can be improved. Accordingly, it is possible to effectively utilize the dynamic range of the display unit. Further, according to the image input / output device of claim 4, the gradation control means includes a tone curve table set so that a target exposure area of the image data is expressed in gradation on the display means. , According to a target luminance value of the image data,
And a tone curve table switching means for switching the tone curve table.

Thus, even when the target luminance value changes, only by switching the tone curve table,
The exposure area corresponding to the target luminance value can be displayed with a predetermined number of gradations, and the number of gradations in an arbitrary area can be easily increased or decreased according to the user's preference. Further, according to the image input / output device of the fifth aspect, the gradation control means includes an offset giving means for giving an offset corresponding to the target luminance value or the photometric evaluation value to the tone curve table. And

Thus, by preparing only one tone curve table, the exposure area corresponding to the target luminance value or the photometric evaluation value can be displayed with a predetermined number of gradations, and when the brightness of the subject changes. Also, it is possible to maintain the number of gradations at the time of imaging the subject. Further, according to the image input / output device of claim 6, the gradation control means performs gradation control of the image pickup data using a linear tone curve during manual exposure.

Thus, at the time of manual exposure, image pickup can be performed while confirming the actual contrast at the time of image pickup, and the display means can be used as a finder. According to the image input / output device described in claim 7, the image input / output device is a digital camera, a digital video camera, a videophone, or a mobile terminal with a camera.

Thus, the tone processing is performed in the own apparatus and displayed on the own apparatus side, the image data after the tone processing performed in another apparatus is displayed on the own apparatus, or the own apparatus performs the gradation processing. The image data after the gradation processing can be displayed on another device, the gradation processing can be performed in the own device and displayed on the own device side, and the gradation processing can be performed according to the purpose. Can be performed efficiently.

Further, according to the image conversion method of the present invention, the tone curve is controlled according to the brightness of the imaging target so that the imaging target is expressed by a predetermined number of gradations. . Thus, even when the brightness of the imaging target changes, it is possible to display the imaging target with a predetermined number of gradations only by controlling the tone curve, and even when the dynamic range of the display unit is narrow. In addition, it is possible to display an image with less discomfort with a simple configuration.

According to the image conversion program of the ninth aspect, the step of acquiring the image data and the step of controlling the gradation of the image data based on the exposure information of the image data are executed by a computer. It is characterized by making it. With this, even when the dynamic range of the display unit is narrower than the dynamic range of the image data output from the imaging unit, it is possible to display a target portion with a predetermined number of gradations by simply changing the software. It is possible to display an image with less discomfort without changing hardware.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image input / output device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a block diagram showing a schematic configuration when an image input / output device according to an embodiment of the present invention is applied to a digital video camera. In FIG. 1A, the digital video camera 101 is provided with an imaging data acquisition unit 101a, a gradation control unit 101b, and a display unit 101c. Here, the imaging data acquiring unit 101a acquires the imaging data, and outputs the acquired imaging data to the gradation control unit 101b together with the exposure information RI of the imaging data. For example, an image sensor that captures an image of a subject, Exposure control means for controlling exposure at the time of imaging can be used. The gradation control unit 101b controls the gradation of the image data based on the exposure information RI of the image data output from the image data acquisition unit 101a. Note that the exposure information RI is a target luminance value and a photometric evaluation value.

For example, the imaging data acquiring means 101a has 8
Assuming that the display unit 101c displays 6-bit display data, the gradation control unit 101b converts the 8-bit image data into 6-bit display data based on the exposure information RI. Then, the display data is output to the display unit 101c. Here, the gradation control unit 101b, for example, of the 8-bit image data,
The imaging data is converted so that the target exposure area of the imaging data is expressed in gradation on the display unit 101c.
When the target luminance value is changed, the imaging data is converted so that the portion expressed in gradation on the display unit 101c follows the change in the target luminance value. Further, when the brightness of the image data does not reach the target luminance value, the image data is converted so that the photometry evaluation area of the image data is expressed in gradation on the display unit 101c. Note that the target exposure area and the photometry evaluation area may be changed according to the subject.

Thus, even when the gradation displayed by the display means 101c is narrower than the gradation at the time of imaging, the gradation of a portion to be displayed can be maintained while performing imaging with a target exposure. It is possible to reduce the gradation of an unnecessary portion of the image, and it is possible to reduce a sense of discomfort when the image data is displayed with a small number of gradations. FIG. 1B is a block diagram illustrating a schematic configuration when the image input / output device according to the embodiment of the present invention is applied to a digital camera. In FIG. 1B, the digital camera 201 includes an imaging data acquisition unit 2
01a and a gradation control unit 201b, the imaging data acquisition unit 201a outputs, for example, 8-bit imaging data and exposure information RI to the gradation control unit 201b, and the gradation control unit 201b performs processing based on the exposure information RI. To convert 8-bit image data into 6-bit display data. Then, the gradation control unit 201b transmits the 6-bit display data to the display unit 203 via the communication network 202.
Output to Note that the communication network 202 can use a telephone line, a LAN, the Internet, a mobile phone network, a short-range wireless data communication technology “Bluetooth”, or the like.

As described above, by performing the gradation processing of the image data based on the exposure information RI on the digital camera 201 side, the image data is transmitted to the display means 203, and the gradation of the optimal exposure portion of the image data is obtained. The imaging data can be displayed on the display unit 203 while maintaining the tonality, and the sense of discomfort when the imaging data is displayed with a small number of gradations can be reduced.

FIG. 1C is a block diagram showing a schematic configuration when the image input / output device according to the embodiment of the present invention is applied to a videophone. In FIG. 1C, a videophone 301 on the transmission side includes an imaging unit 301a and an imaging data transmission unit 301b, and a videophone 303 on the reception side.
Are imaging data acquisition means 303a, gradation control means 303
b and display means 303c. Note that the transmitting side and the receiving side are for convenience of explanation,
Actually, each of the videophones 301 and 303 is
01a, imaging data transmission unit 301b, imaging data acquisition unit 303a, gradation control unit 303b, and display unit 3
03c.

Here, the image data transmitting means 301b, for example, 8-bit image data picked up by the image pickup means 301a and its exposure information RI are transmitted to the communication network 30.
2 to the other party's videophone 303. Upon receiving the imaging data and the exposure information RI thereof, the imaging data acquiring unit 303a converts the data into the gradation control unit 3
03b. Upon receiving the imaging data and its exposure information RI, the gradation control unit 303b converts the 8-bit imaging data into 6-bit display data based on the exposure information RI, and outputs the display data to the display unit 303c. .

As described above, the imaging data and the exposure information RI thereof are transmitted to the display means 303c, and the display means 303c
By performing the gradation processing on the c side, the display means 303c
Even if the dynamic range is not known on the transmission side, gradation processing suitable for the display means 303c can be performed, and the sense of discomfort when image data is displayed with a small number of gradations can be reduced.

FIG. 2 is a block diagram showing a detailed configuration of the digital video camera shown in FIG. In the embodiment of FIG. 2, a gradation control unit 6a and a tone curve logic 6b are provided instead of the tone curve unit 6 of FIG. Further, the imaging data acquisition means 10 shown in FIG.
1a is an image sensor 1 and an exposure control unit 2 of FIG.
The gradation control unit 101b in FIG. 1A corresponds to the gradation control unit 6a and the tone curve logic 6b in FIG. 2, and the display unit 101c in FIG. 1A corresponds to the display device 8 in FIG.

In FIG. 2, an image sensor 1 captures a still image or a moving image. For example, a CMOS sensor or a CCD imager can be used. Here, as shown in FIG. 3A, the image sensor 1 includes a sensor unit 1a for converting light received by the image sensor 1 into an electric signal, a programmable gain amplifier 1b for amplifying the electric signal, and a digital signal for converting the analog signal into a digital signal. A /
The D converter 1c is provided. Output data SD output from the image sensor 1 is input to the image processing logic 4 and the photometry logic 2a.

The exposure control section 2 controls the exposure of the image sensor 1 and automatically adjusts the brightness level. The exposure control section 2 includes a photometry logic 2a and a timing & sensor control section 2b. The photometry logic 2a performs photometry based on the output data SD from the image sensor 1, and calculates a photometric evaluation value S
R is the timing & sensor control unit 2b and the gradation control unit 6
output to a. Here, when photometry is performed based on the output data SD, for example, center-weighted photometry can be performed, and in this case, photometry processing can be performed around the subject H to be imaged. Further, as the photometry process, the brightness B of the subject H can be obtained by calculating the average value of the luminance values of the output data SD in the photometry evaluation area.

The timing & sensor control unit 2b drives the timing generator 3 based on the drive mode KM input from the digital system 9,
The gain value GC and the shutter speed SP are calculated such that the photometric evaluation value SR input from the photometric logic 2a matches the target luminance value AK input from the digital system 9. Then, output data S from the image sensor 1
The calculated gain value GC so that D becomes a predetermined level.
Is output to the programmable gain amplifier 1b of FIG. 2A, and the shutter speed SP is output to the timing generator 3.

The timing generator 3 generates a drive signal for driving the image sensor 1 based on the shutter speed SP output from the timing & sensor control section 2b, and drives the image sensor 1. Image processing logic 4
Performs image processing on the output data SD and outputs the synchronization signal DS1
Data GD in synchronization with the tone curve logic 6b
Output to

The tone control section 6a controls the tone curve based on the photometric evaluation value SR and the target luminance value AK. As shown in FIG.
1 and a tone curve control unit 12. The sensor signal luminance calculator 11 receives the target luminance value AK from the digital system 9 and the photometric evaluation value SR from the photometric logic 2a, and determines whether the photometric evaluation value SR matches the target luminance value AK. Is determined. Further, the tone curve control section 12 outputs a control signal TK for controlling the tone curve to the tone curve logic 6b based on the output from the sensor signal luminance calculation section 11.

The tone curve logic 6b performs gradation processing of the image data GD based on the control signal TK output from the gradation control section 6a. A tone curve for performing gradation processing of the image data GD is provided. Holding. The display interface unit 7 absorbs the difference between the transmission rate of the display data HD output from the camera and the transmission rate of the display data HD input to the display device 8, and includes a display control unit 7a and a video memory 7b. It has. Here, the display controller 7a stores the display data HD output from the tone curve logic 6b on the video memory 7 based on the synchronization signal DS1 output from the image processing logic 4.
b, and reads out the display data HD stored in the video memory 7b based on the synchronization signal DS2 output from the display device 8,
Output to

The display device 8 displays an operation screen when used as a mobile phone, an image transmitted from a partner when used as a videophone, a finder image when used as a video camera, and the like. A transflective liquid crystal display device can be used. This transflective type liquid crystal display device has both a reflection type and a transmission type function, and has a display & synchronization signal generation unit 8a and a backlight 8b.
Is provided. When the surroundings are dark, the backlight 8b is turned on and used as a transmissive type, and when the surroundings are bright, the backlight 8b is turned off and used as a reflective type. 8b can be reduced.

The digital system 9 can be constituted by, for example, a microcomputer or the like, and provides a man-machine interface. Then, the target brightness value AK and the drive mode KM set by default or manual operation are output to the timing & sensor control unit 2b, and the target brightness value AK is output to the gradation control unit 6a.

The functions of the exposure control section 2, the gradation control section 6a and the like can be realized by reading a program for realizing these functions and executing the program by the CPU. FIG. 4 is a diagram illustrating a tone curve control method according to the first embodiment of the present invention. In FIG. 4, from the image sensor 1 side, in the case of color, RGB
In the case of each color or monochrome, it is assumed that the image data GD of a single color and 256 gradations is output, and the display device 8 has only the display capability of the display data HD for 64 gradations. In this case, 8
In the method of thinning out the two bits on the LSB side from the image data GD for bits, the tone curve TC1 becomes a straight line, and the gradation is uniformly compressed over the entire luminance area of the image data GD output from the image sensor 1 side. Is performed.

Therefore, the dynamic range DK1 of the image data GD output from the image sensor 1 is converted into the dynamic range DH1 of the display device 8, and if the dynamic range of the image of the subject H is DK2, The image is displayed on the display device 8 in the dynamic range DH2. Here, the exposure of the portion of the subject H is controlled by the exposure control function of the image sensor 1 so that the target brightness value AK is obtained, and the portion falls within a predetermined gradation range from the target brightness value AK. For this reason, in an image captured by the image sensor 1, an extremely dark portion or an extremely bright portion included in the background is removed even if the portion is captured with a gradation on the image sensor 1. Display device 8
When the image is displayed on the display, there is a high possibility that the portion is other than the subject H. Therefore, even if the gradation of this portion is reduced, the user does not feel much discomfort.

On the other hand, a linear tone curve TC1
Is used, even if an area other than the subject H is displayed along with the gradation on the display device 8, the user does not pay much attention to that part, so that it has little meaning to the user. . Therefore, when the subject H is imaged so as to match the target luminance value AK, the tone curve TC2 in which the slope of the appropriate exposure area of the subject H is steep and the slope of the other areas is gentle is used. Perform gradation processing of the image data GD.

When the tone curve TC2 is used, an image of the subject H in the dynamic range DK2 can be displayed on the display device 8 in the dynamic range DH1, and the dynamic range DH1 inherent in the display device 8 can be displayed. Can be used to display an image of the subject H. On the other hand, if this tone curve TC2 is used, an area outside the proper exposure range of the subject H, even if it has a gradation on the image sensor 1,
On the display device 8, it is displayed as a blackout area or an overexposed area, and the gradation of that part disappears. However, this part is an area other than the subject H and the user does not pay much attention, so the discomfort is not so much. Does not occur.

Further, when the target luminance value AK is changed, the tone curve TC2 is translated so that the target luminance value AK is located at the center of the steep portion of the tone curve TC2. Thereby, even when the exposure value of the subject H is changed, the gradation of the subject H can be maintained, and
It is possible to display an image without a sense of discomfort. FIG.
It is a figure showing a control method of a tone curve concerning a 2nd embodiment of the present invention. In FIG. 5, a subject H has a target luminance value A.
In the case of the brightness K1 that can be matched with K, the tone curve TC2 is translated so that the target brightness value AK is at the center of the steep part of the tone curve TC2. Accordingly, an image of the subject H can be displayed by effectively using the dynamic range DH1 originally included in the display device 8.

On the other hand, if the brightness of the subject H is so dark that it cannot be matched with the target brightness value AK, gradation processing is performed using the tone curve TC2. However, the image is completely crushed on the display device 8. For this reason, the tone curve TC3 is translated so that the photometric evaluation value SR comes to a steep part of the tone curve TC3. Thus, even when the subject H is dark, the subject H can be displayed on the display device 8 while maintaining the gradation of the subject H at that time.

FIG. 6A is a block diagram showing a first configuration example of the tone curve logic 6b of FIG. FIG.
In (a), the tone curve logic 6b includes a plurality of tone curves T1 to T1 corresponding to different target luminance values AK.
Tn is provided, and the tone curve switching unit 21 switches the switch SW based on the control signal TK from the gradation control unit 6a.
1. Switch SW2. Thereby, the target luminance value AK
Can always be controlled such that is always at the center of the steep portion of the tone curve TC2, and the gradation of the subject H can be maintained even when the exposure value of the subject H is changed. .

FIG. 6B is a block diagram showing a second configuration example of the tone curve logic 6b of FIG. FIG.
In (b), the tone curve logic 6b is provided with a tone curve TC2, and the offset generating unit 23
Based on the control signal TK from the gradation control unit 6a, a positive or negative offset corresponding to the target luminance value AK or the photometric evaluation value SR is generated, and the offset is output to the adder 22. The adder 22 adds the offset output from the offset generator 23 to the image data GD, and outputs the addition result to the tone curve TC2. Accordingly, even when the target luminance value AK or the photometric evaluation value SR fluctuates, the gradation of the subject H can be maintained by providing only one tone curve TC2.

FIG. 7 is a flowchart showing a tone curve control method according to an embodiment of the present invention. In FIG. 7, it is determined whether or not the display device 8 is used as a finder for exposure adjustment (step S1). When the display device 8 is used as a finder for exposure adjustment, the tone curve TC2 is changed. Returning to the tone curve TC1, gradation processing is performed (step S2).

On the other hand, if the display device 8 is not used as a finder for exposure adjustment, it is determined whether or not the photometric evaluation value SR matches the target luminance value AK (step S3). When the target brightness value AK matches, the tone curve TC2 is used instead of the tone curve TC1, and as shown in FIG.
The steep part 2 is made to follow the target luminance value AK (step S4). On the other hand, when the photometric evaluation value SR does not match the target luminance value AK, as shown in FIG.
The steep part of No. 3 is made to follow the photometric evaluation value SR (step S5).

Thus, even when the brightness H of the subject H changes or when the target luminance value AK is changed, the display on the display device 8 is maintained while maintaining the gradation of the subject H. It is possible to do. In the above-described embodiment, the image sensor 1 is used as an imaging unit that performs imaging, the display device 8 is used as a display unit that displays an image, the exposure control unit 2 is used as an exposure control unit that controls exposure of the imaging unit, and the control of the exposure control unit is performed. Although the case where the tone control unit 6a and the tone curve logic 6b are used as the tone control unit for controlling the tone of the image data output from the imaging unit based on the state has been described as an example, the present invention has this configuration. Various other changes are possible without being limited to the examples. For example, the gradation control unit 6a and the tone curve logic 6b may be configured by a dedicated IC such as an ASIC,
Further, the present invention may be realized by executing a computer program by a CPU.

Further, in the above-described embodiment, the case where a polygonal tone curve is used as the tone curve TC2 has been described. However, the slope of the tone curve TC2 may be smoothly changed in an S-shape. Target luminance value AK
Alternatively, the inclination of the steep portion may be increased or decreased according to the magnitude of the photometric evaluation value SR. The display device 8 may be a liquid crystal display device, a CRT, a plasma display, an EL display, or the like.
A display or the like may be used.

[0050]

As described above, according to the present invention,
Even when the dynamic range of the display means is narrower than the dynamic range of the image data output from the image means, an image with less discomfort can be displayed on the display means.

[Brief description of the drawings]

FIG. 1A is a block diagram showing a schematic configuration when an image input / output device according to an embodiment of the present invention is applied to a digital video camera, and FIG. 1B is an embodiment of the present invention. 1C is a block diagram showing a schematic configuration when the image input / output device according to the present invention is applied to a digital camera, and FIG. 1C shows a schematic configuration when the image input / output device according to the embodiment of the present invention is applied to a videophone. FIG.

FIG. 2 is a block diagram illustrating a detailed configuration example of the digital video camera in FIG.

3A is a block diagram illustrating a detailed configuration example of the image sensor 1 in FIG. 2, and FIG. 3B is a block diagram illustrating a detailed configuration example of the gradation control unit 10 in FIG. FIG.

FIG. 4A shows a tone curve logic 6 shown in FIG. 2;
4B is a block diagram showing a first configuration example, and FIG. 4B is a block diagram showing a second configuration example of the tone curve logic 6b in FIG.

FIG. 5 is a diagram illustrating a tone curve control method according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a tone curve control method according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a tone curve control method according to an embodiment of the present invention.

FIG. 8 is a block diagram showing a schematic configuration of a conventional image input / output device.

[Explanation of symbols]

 101 Digital video camera 101a, 201a, 301a Image data acquisition means 101b, 201b, 303b Tone control means 101c, 203, 303c Display means 201 Digital camera 202, 302 Communication network 301, 303 Videophone 301a Imaging means 301b Image data transmission means Reference Signs List 1 image sensor 1a sensor unit 1b programmable gain amplifier 1c A / D converter 2 timing & sensor control unit 3 timing generator 4 image processing logic 5 photometry logic 6a gradation control unit 6b tone curve logic 7 display interface unit 7a display control unit 7b Video memory 8 Display device 8a Display & sync signal generator 8b Backlight 9 Digital system 11 Sensor signal brightness calculator 12 Tone curve control Unit 21 tone curve switching unit 22 adder 23 offset generation unit

Continued on the front page F term (reference) 5B057 AA01 CA08 CA12 CB08 CB12 CC01 CE11 CH01 CH07 DA16 5C021 PA71 PA78 XA35 5C022 AA11 AA13 AB06 AB17 AC03 AC42 AC69 5C064 AA01 AC02 AC12 AD06 AD08 5C077 LL04 MM02 PP15 PP43 PP43 PP43 PP43

Claims (9)

[Claims] 1. An image input / output device comprising: image data acquisition means for acquiring image data; and gradation control means for controlling the gradation of the image data based on exposure information of the image data. apparatus. 2. The image processing apparatus according to claim 1, wherein the gradation control unit controls a target exposure area of the image data to be expressed in gradation on a display unit.
2. The image input / output device according to claim 1, wherein a gradation of the image data is controlled. 3. The image processing apparatus according to claim 1, wherein the gradation control unit is configured to, when the brightness of the image data does not reach the target luminance value, cause the photometric evaluation area of the image data to be expressed in gradation on a display unit. The image input / output device according to claim 1, wherein the gradation is controlled. 4. A tone curve table in which a target exposure area of the image data is set to be expressed in a gradation on the display means, according to a target brightness value of the image data. 4. The image input / output apparatus according to claim 2, further comprising a tone curve table switching means for switching the tone curve table. 5. The image input / output apparatus according to claim 4, wherein said gradation control means includes an offset giving means for giving an offset corresponding to said target luminance value or photometric evaluation value to said tone curve table. . 6. The image processing apparatus according to claim 1, wherein said gradation control means performs gradation control of said image data using a linear tone curve during manual exposure. Image input / output device. 7. The image input / output device according to claim 1, wherein the image input / output device is a digital camera, a digital video camera, a videophone, or a mobile terminal with a camera. . 8. An image conversion method, wherein a tone curve is controlled in accordance with the brightness of an imaging target so that the imaging target is expressed by a predetermined number of gradations. 9. An image conversion program for causing a computer to execute a step of acquiring image data and a step of controlling a gradation of the image data based on exposure information of the image data.