JPH06197266A - Lens and image pickup device - Google Patents

Abstract

PURPOSE:To compensate shading in the horizontal and vertical directions automatically in response to the kind and diaphragm of a lens. CONSTITUTION:A horizontal address signal Hn and a vertical address signal Vn are fed to a decoder 9 from a drive circuit 8. Then shading data (a) of a standard lens corresponding to the addresses Hn, Vn are outputted from the decoder 9. The shading data (a) are compensated by a shading compensation coefficient k1 corresponding to a kind of a lens and a shading compensation coefficient k2 corresponding to a diaphragm of the lens stored in a ROM 11 of an image pickup lens 1, and the compensated data are converted into a reference voltage refV by a D/A converter 14. Then an image pickup signal SD outputted from an analog signal processing circuit 4 based on the reference voltage refV. Thus, a precise picture signal SE subject to shading compensation is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens and an image pickup apparatus suitable for application to an electronic still camera or the like.

[0002]

2. Description of the Related Art There is a digital electronic still camera as an image pickup device capable of recording a still image on, for example, a memory card. In this digital electronic still camera, as shown in FIG. 5, image pickup light input from the image pickup lens 1 is photoelectrically converted by a solid-state image pickup device such as a CCD 2, amplified by an amplifier 3, and supplied to an analog signal processing circuit 4. It

In the analog signal processing circuit 4, predetermined signal processing such as shading correction is performed, and this is A / D.
It is supplied to the converter 5, converted into a digital signal here, and then subjected to predetermined signal processing in the digital signal processing circuit 6 and stored in the memory card 7.

[0004]

By the way, the image pickup lens 1 has a characteristic that the image pickup light output through the peripheral portion of the lens body becomes darker than the image pickup light output through the central portion. In order to prevent the original image data from changing due to such characteristics of the image pickup lens 1, in the conventional electronic still camera, the analog signal processing circuit 4 normally performs the shading correction as described above. .

Shading correction is performed as follows. That is, the signal SA output from the amplifier 3 when a subject having the same brightness is imaged gradually decreases in level toward both sides due to the characteristics of the imaging lens 1, as shown in FIG. It is supplied to the gain control amplifier 41 of the circuit 4. Here, the gain is controlled by the control signal SB whose level gradually increases toward both sides, and the data SC of substantially the same level is corrected. As a result, the influence of the characteristics of the image pickup lens 1 is prevented.

However, in an electronic still camera, the image pickup lens 1 may be replaced with various lenses such as a wide-angle lens and a telephoto lens. In this case, since the shading characteristics of the image pickup lens 1 are different from each other, the control signal SB is set to this value. Must be adjusted according to. Therefore, the electronic still camera is equipped with a device for manually adjusting the control signal SB, but in reality, it is not used effectively because the adjustment is difficult and troublesome.

In order to obtain accurate image pickup data, the control signal S is changed even when the diaphragm of the image pickup lens 1 is changed.
B must be changed, and since the image pickup lens 1 is circular, the control signal SB must be adjusted in the vertical direction at the same time as the adjustment in the horizontal direction. Was not adjusted.

Therefore, the present invention solves the above-mentioned problems, and a lens and an image pickup capable of automatically performing horizontal and vertical shading correction in accordance with the type and diaphragm of the image pickup lens. It proposes a device.

[0009]

In order to solve the above-mentioned problems, the first invention is characterized in that the image pickup lens is provided with a storage means for storing the shading correction coefficient.

According to the second aspect of the present invention, an image pickup lens having storage means for storing shading correction coefficients, an image pickup device for photoelectrically converting the image pickup light outputted from the image pickup lens into an image pickup signal, and shading data for each address of the standard lens. And a look-up table in which is stored, a means for supplying an address signal to the decoder or the look-up table, a means for correcting shading data output from the decoder or the look-up table with a shading correction coefficient, and a corrected shading It is characterized in that it is provided with means for generating a reference voltage based on the data and means for converting the image pickup signal into a digital signal based on the reference voltage.

According to the third aspect of the present invention, the image pickup lens having a storage means for storing the shading correction coefficient, the image pickup device for photoelectrically converting the image pickup light output from the image pickup lens into the image pickup signal, and the image pickup device attached to the front surface of the image pickup device. Decoder or lookup table storing shading data for each address of the standard lens set corresponding to the presence or absence of a microlens, means for supplying an address signal to the decoder or lookup table, and decoder or lookup Means for correcting the shading data output from the table with the shading correction coefficient, means for generating a reference voltage based on the corrected shading data, and means for converting the image pickup signal into a digital signal based on the reference voltage. It is characterized by having.

[0012]

In FIG. 1, the drive circuit 8 outputs a vertical transfer signal SV and a horizontal transfer signal SH, which drives the CCD 2. The address signals Vn and Hn are obtained by counting the vertical transfer signal SV and the horizontal transfer signal SH. Address signals Hn, Vn
Is also supplied to the decoder 9. As a result, the standard lens shading data a (FIG. 2B) corresponding to the addresses Hn and Vn are output from the decoder 9. The shading data a also differs depending on the presence or absence of a microlens that can be attached to the front surface of the CCD 2.

The shading data a output from the decoder 9 is a shading correction coefficient k1 corresponding to the type of lens stored in the ROM 11 of the image pickup lens 1.
And the shading correction coefficient k corresponding to the aperture of the lens
2 is corrected, and this is converted into the reference voltage refV (FIG. 3A) by the D / A converter 14.

Then, the image pickup signal SD output from the analog signal processing circuit 4 based on the reference voltage refV.
(FIG. 3B) is converted into a digital signal. This makes it possible to obtain an accurate image signal SE with shading correction as shown in FIG.

[0015]

Next, one embodiment of the lens and the image pickup apparatus according to the present invention will be described in detail with reference to the drawings.
The same parts as those described above are designated by the same reference numerals and detailed description thereof is omitted.

FIG. 1 shows the configuration of a lens and an image pickup device according to the present invention. In the figure, the image pickup light input from the image pickup lens 1 is photoelectrically converted by the CCD 2, and the image pickup signal SA is passed through an amplifier 3, an analog signal processing circuit 4, an A / D converter 5 and a digital signal processing circuit 6 to a memory card. 7 and stored.

Each element of the CCD 2 is driven by the vertical transfer signal SV and the horizontal transfer signal SH supplied from the drive circuit 8. Further, the vertical address signal Vn and the horizontal address signal Hn can be obtained by counting the vertical transfer signal SV and the horizontal transfer signal SH. The horizontal address signal Hn and the vertical address signal Vn are also supplied to the decoder 9. The decoder 9 stores standard shading data a. A look-up table may be used instead of the decoder 9.

This shading data a is for a standard lens, and horizontal addresses H1 to H5 and vertical addresses V1 to V5 are set in the standard lens 1A as shown in FIG. As shown in (B), standard shading data a for each address H1 to H5 is set. Here, the shading data a at the addresses V1 to V5 in the vertical direction are further determined.

The shading data a changes depending on the presence or absence of a microlens that can be attached to the front surface of the CCD 2, and the decoder 9 stores both shading data a. Then, the presence / absence of the microlens is supplied from the CCD 2 and the shading data a is output.

The shading data a output from the decoder 9 is supplied to the multiplication circuit 10. This multiplication circuit 1
The lens correction coefficient k1 stored in the ROM 11 of the imaging lens 1 is also supplied to 0, and this is multiplied by the shading data a. The lens correction coefficient k1 varies depending on the type of lens, that is, a standard lens, a wide-angle lens, a telephoto lens, and even the same type of lens varies depending on the manufacturer and is a coefficient unique to the lens. The lens correction coefficient k1 includes an offset.

The output of the multiplying circuit 10 is supplied to the adding circuit 11, where the offset of the lens correction coefficient k1 is added. This completes the shading correction depending on the type of lens.

Next, the output signal b of the adder circuit 11 is supplied to the multiplier circuit 12. The ROM 11 supplies the diaphragm correction coefficient k2 corresponding to the diaphragm at that time and multiplies the signal b by the diaphragm correction coefficient k2. The aperture correction coefficient k2 is output when the aperture value (not shown) of the imaging lens 1 supplies the aperture value to the ROM 11. The output of the multiplication circuit 12 is supplied to the addition circuit 13, where the offset of the aperture correction coefficient k2 is added. This completes the shading correction by the diaphragm.

The output of the adder circuit 13 is supplied to the D / A converter 14, where the reference voltage re as shown in FIG.
converted to fV. This reference voltage refV is supplied to the A / D converter 5. Now, when an image in which a white rectangle is drawn on a black background as shown in FIG. 4 is picked up by this image pickup apparatus, a signal SD whose both ends gradually decrease in level as shown in FIG. It is output from the processing circuit 4.

In the signal SD, the signals picked up above and below the image pickup lens 1, that is, the signals taken at the upper and lower positions (a) and (c) of the object are at the central position (a). The level will be lower than when the image was taken. This is due to the characteristics of the image pickup lens as described above.

This signal SD is supplied to the A / D converter 5, where it is converted into a digital signal based on the reference voltage refV. As a result, the level reduction on both sides of each signal and the level reduction due to the position of the lens are corrected as shown in FIG. 7C, and accurate image data is obtained.

As described above, in the image pickup apparatus of the present invention, the reference voltage refV is determined corresponding to the type of lens, the presence / absence of the microlens, and the diaphragm, and the image pickup data is converted into a digital signal based on the reference voltage refV. Therefore, it becomes possible to automatically obtain an accurate image.

Further, since complicated analog signal processing is not required at the time of shading correction and only digital signal processing is required, the shading correction circuit can be easily integrated into an LSI. Further, special image processing can be performed by changing the shading data stored in the decoder 9 or the look-up table.

In the above embodiment, the case where the ROM 11 storing the lens correction coefficient k1 and the aperture correction coefficient k2 is attached to the image pickup lens 1 has been described.
It is also possible to attach 1 to the image pickup apparatus main body side. In this case, the ROM 11 stores the lens correction coefficient k1 and the aperture correction coefficient k2 for various lenses, and
For example, the lens type and the aperture value may be supplied from the imaging lens 1.

[0029]

As described above, according to the present invention, the lens or the image pickup apparatus main body is provided with the storage means for storing the shading correction coefficient, and the shading data corrected by the shading correction coefficient is converted into the reference voltage. The image pickup signal is converted into a digital signal based on the reference voltage.

Therefore, according to the present invention, even if the lens is exchanged, it is not necessary to manually adjust the shading data as in the conventional case, and the correction in the vertical direction and the correction by the diaphragm can be performed, so that an accurate image can be obtained. Can be easily obtained. Furthermore, the shading correction circuit
There is an effect that SI can be easily performed, and special image processing can be easily performed.

[Brief description of drawings]

FIG. 1 is a system diagram of a digital electronic still camera to which a lens and an imaging device according to the present invention are applied.

FIG. 2 is a diagram illustrating an address of a standard lens and shading data.

FIG. 3 is a signal waveform diagram of an example.

FIG. 4 is a diagram illustrating an example of a subject.

FIG. 5 is a system diagram of a general digital electronic still camera.

FIG. 6 is a diagram illustrating conventional shading correction.

[Explanation of symbols]

 1 Imaging Lens 2 CCD 3 Amplifier 4 Analog Signal Processing Circuit 5 A / D Converter 6 Digital Signal Processing Circuit 7 Memory Card 8 Drive Circuit 9 Decoder 14 D / A Converter

Claims (7)

[Claims] 1. A lens for imaging, comprising a storage means for storing a shading correction coefficient. 2. The lens according to claim 1, wherein the shading correction coefficient is a coefficient corresponding to both or one of a lens type and an aperture. 3. An image pickup lens having storage means for storing shading correction coefficients, an image pickup device for photoelectrically converting image pickup light output from the image pickup lens into an image pickup signal, and shading data for each address of a standard lens is stored. Decoder or look-up table, means for supplying an address signal to the decoder or look-up table, means for correcting shading data output from the decoder or look-up table with the shading correction coefficient, and An image pickup apparatus comprising: a unit that generates a reference voltage based on shading data; and a unit that converts the image pickup signal into a digital signal based on the reference voltage. 4. The image pickup apparatus according to claim 3, wherein the address signals are vertical and horizontal address signals, and the shading data is also corrected in the vertical direction. 5. The image pickup apparatus according to claim 3, wherein the shading correction coefficient is a coefficient corresponding to both or one of the lens type and the diaphragm. 6. An image pickup lens having a storage means in which shading correction coefficients are stored, an image pickup device for photoelectrically converting the image pickup light output from the image pickup lens into an image pickup signal, and the image pickup device can be attached to the front face of the image pickup device. A decoder or lookup table storing shading data for each address of a standard lens set corresponding to the presence or absence of a microlens, means for supplying an address signal to the decoder or lookup table, and the decoder or lookup Means for correcting the shading data output from the table with the shading correction coefficient, means for generating a reference voltage based on the corrected shading data, and converting the imaging signal into a digital signal based on the reference voltage. And an imaging method comprising: apparatus. 7. The image pickup apparatus according to claim 6, wherein the address signals are horizontal and vertical address signals, and the shading data is also corrected in the vertical direction.