JPH11313250A - Camera having provision for interchangeable lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost and the weight of a lens by correcting differences in distortions between a reference pattern photographed by means of a camera and an image output obtained from the camera with a correction means such as a digital signal processor so as to correct aberrations through an operation inside the camera. SOLUTION: An R(red) signal, a G(green) signal and a B(blue) signal are obtained by supplying an image pickup output from a CCD including a camera section and a solid-state image pickup element in an ENG camera or the like to a 3 CCD blocks 3, where the image output is separated into the R, G, B signals. The R, G, B signals are fed respectively to an R amplifier 4R, a G amplifier 4G and a B amplifier 4B, where the signals are amplified. The amplified signals are fed to an A/D converter circuit 8, in which the signals are converted into digital data. Then a video signal for the image is outputted to an output terminal 12 via a digital signal processor DSP 9 that is a signal processing means. In this case, differences in distortions between a reference pattern 10 photographed by means of a camera 1 and an image output obtained from the camera 1 is corrected with a correction means 8 such as the digital signal processor 9 to obtain a normal image output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interchangeable lens-compatible camera suitable for use in an image pickup means such as a CCD in which various types of image pickup lenses can be mounted, and more particularly, to an interchangeable lens for correcting lens aberration. For compatible cameras.

[0002]

2. Description of the Related Art Conventionally, in an image pickup device such as a television camera using a CCD or the like, the image quality such as distortion of a video signal obtained from the image pickup device is theoretically not likely to occur in the CCD. However, the cause of the distortion largely depended on the lens of the imaging camera.

[0003]

Among the image quality-related factors obtained as the output of the camera through the lens as described above,
There are factors known as Seidel's five aberrations as factors possessed by lenses. To reduce these aberrations, low-dispersion glass is used as the lens material, and a large number of lenses are used in order to improve resolution. High quality EFP (Electronic Field Production) to eliminate combination and distortion
Lenses are being forced to increase in size.
For this reason, ENG (Electronic New)
s Gathering) The camera had to have various aberrations, including distortion performance.

The present invention has been made to solve the above problems, and an object of the present invention is to improve distortion among the above-mentioned five aberrations. . This distortion not only relates to the weight of the lens, but also reveals the quality of the image at a glance. The present invention seeks to solve this problem on the camera side without depending on the lens. Also, as the focal length changes during zooming, the distortion changes in relation to the focal length, so that a means for correcting each focal length is provided. Further, the objective is to immediately correct distortion, which exhibits unique characteristics when a lens is replaced, for each lens when the lens is attached or detached.

[0005]

According to a first aspect of the present invention, there is provided a camera compatible with an interchangeable lens, wherein a difference between a reference pattern taken through the camera and a distortion of an image output obtained from the camera is converted into a digital signal. The correction is performed by correction means 8 such as a processor (hereinafter referred to as a DSP) or the like so that a normal image output is obtained.

A camera compatible with an interchangeable lens according to a second aspect of the present invention is configured to correct distortion in conjunction with a lens state of a drive servo system 5 of a zoom lens of the camera 1 or the like.

A camera compatible with an interchangeable lens according to a third aspect of the present invention includes a correction data storage means 7 in the lens body 2 of the camera 1, and is attached to the camera 1 by mounting the lens body on the camera 1. The correction data is transmitted.

According to the first aspect of the present invention, the distortion of the lens can be digitally easily corrected by using a DSP having the camera body. According to the third aspect of the present invention, it is possible to correct the distortion of the lens corresponding to the lens when the lens is replaced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to an interchangeable lens compatible camera such as an ENG camera equipped with a CCD shown in FIG.
This will be described with reference to FIG.

FIG. 1 is a system diagram of an interchangeable lens camera according to the present invention, and FIG. 2 is a diagram for explaining distortion of a camera lens.

In FIG. 1, reference numeral 1 denotes a camera body. For example, in an ENG camera or the like, a single focus lens is rarely used, and a zoom lens 2 is mostly used.

In an ENG camera or the like as an image pickup means, an image pickup output from a CCD including a camera unit and a solid-state image pickup device such as a CCD is supplied to a CCD block 3, and R (red), G
The R, G, and B signals separated into (green) and B (blue) are supplied to an R amplifier 4B, a G amplifier 4G, and a B amplifier 4B.
After the amplification, the signal is supplied to an analog-to-digital converter (hereinafter referred to as ADC) 8, converted into digital-data, and converted into a digital signal processor (Digital).
Output terminal 12 via Signal Precesser (DSP) 9 or the like
To output a video signal for the image.

In the present invention, the DSP 9 is used for correcting lens distortion. Then, the output signal from the DPS 9 is supplied to the reference table 7 including a nonvolatile memory for correction and the like.

In the look-up table 7, correction value data for the difference from the normal distortion is output to the DSP 9, and a closed loop circuit is formed and fed back.

Further, since the correction value output from the look-up table 7 varies depending on the focal length of the zoom lens 2 and the like, for example, the zoom position information is transferred to the zoom position through the servo means 5 that performs zoom servo on the zoom lens 2 of the camera 1. Detected by the detection means 6, converted into a digital signal and supplied to the reference table 7, where the correction value corresponding to each focal length can be read. FIG.
And 11 is an erasable RO for a memory card, etc.
M and other memories.

The operation of the camera 1 according to the present invention in the above configuration will be described in detail with reference to FIG.

First, as shown in FIG. 1, for example, a reference pattern 10 such as a cross hatch is picked up as an object by a lens 2 newly mounted on a camera 1.

From the camera 1, the CCD blocks 3 and R,
The cross hatch image digitized by the ADC 8 through the G and B amplifiers 4R, 4G and 4B should have an ideal pattern 15 as shown in FIG. 2C. For example, in a zoom lens or the like in which the lens 2 is not a single focus lens. The distortion is not constant, but when the focal length is changed by zooming, the mode of distortion changes according to the focal length. At a certain focal length, the image of the cross hatch tends to have a pincushion pattern 13 as shown in FIG. 2A. If the focal length is set to another value, the state of distortion may change like the barrel type pattern 14 as shown in FIG. 2B. In particular, it is difficult to correct this aberration particularly in a high-magnification zoom lens.

Therefore, the output of the ADC 8 is corrected by the DSP 9 so that a normal pattern 15 is obtained as shown in FIG. 2C.

The output data output from the DSP 9 is, for example, the values of x and y in the X-axis and Y-axis directions at the cross point 16 of the cross hatch pattern 13 shown in FIG.
_A, from DSP9 if there was a y _A, the value of each cross-point 16 of the crosshatch pattern 13 is supplied to the reference table 7 of the correcting nonvolatile memory.

[0021] the X-axis and Y-axis direction in the reference table 7 in a cross-hatch pattern 15 in FIG. 2C x, values each x _C crosspoint 16 of y, the x When was y _{C C} and y _C Is stored for each cross point 16 as a reference value.

Accordingly, in the DSP 9, each of the reference values is used.
X at the cross point_C-X_A, Y _C-Y_ACalculate
At the X-axis and Y-axis cross points 16, 16 °
2A and FIG. 2C are detected in the X-axis and Y-axis directions.
Then, this is stored in the reference table 7 as a correction value.
The pattern 13 in FIG. 2A is changed to the pattern 15 in FIG.
The pattern can be corrected to a normal pattern.

Further, since the correction value stored in the look-up table 7 varies depending on the focal length of the lens mounted as described above, the zoom position is transmitted as an electric signal by the zoom position information detecting means 6 through the servo means 5 of the electric zoom. By grasping and storing the correction values corresponding to the respective focal length positions in the reference table 7, even if the distortion changes as shown in FIG. Can be done.

In the above-described configuration, the case of the zoom lens has been described. However, the state of the extender 13 and the like, which are provided between the camera and the zoom lens used when the user wants to take a distant subject larger, are included. The change may be detected and corrected.

The storage contents of the non-volatile memory for correction as the above-mentioned reference table 7 can be used as they are at the time of imaging, but are stored in an erasable ROM such as a memory card as shown at 11 in FIG. Then, it may be connected to the DSP 9 and used as a unique correction value of the lens 2 when the camera 1 is set up.

In the above-described configuration, the replacement lens newly mounted on the camera 1 captures and stores a cross hatch in the reference table 7 so as to correct the state of distortion, but this operation is automated as a setup program of the camera itself. It is also possible. That is, when a lens distortion correction command is issued in the camera setup item, zoom driving starts automatically, scanning is performed from the long focal point to the short focal point while performing a correction operation, and the intermediate state is picked up and the DSP is performed.
The correction is made in step 9. Further, it is also possible for the DSP 9 to perform an interpolation operation without storing detailed data in the correction nonvolatile memory 7 one by one. In FIG. 1, the DSP 7 is responsible for the correction processing, but the image distortion can be corrected by controlling the driving clock of the CCD.

According to the present invention, since the correction data is specific to the lens, the data of the lens may be provided by a lens maker as electronic data by electronic recording means. When using the camera, the lens setup data may be a medium such as a setup card, and inserting this card into the camera can save troublesome setup work such as cross-hatch imaging work. A connector is attached to the lens for the purpose of drive servo or the like.However, storage means for storing lens data is stored in the lens body, and the lens data is transmitted from the connector or by information transmission means such as an optical signal. It goes without saying that the image can be corrected by transmitting the signal to the camera body.

[0028]

According to the present invention, the distortion which is conspicuous among the aberrations of the lens as described above can be corrected by the operation inside the camera, which is effective in reducing the cost of the lens and reducing the weight of the lens. It is very effective when applied to cameras for news gathering. In addition, the impression from the consumer of the camera is that high-quality images can be obtained even if the total cost is low, so that the cost can be used for improving the performance of the camera itself. Further, according to this correction method, since the correction value is unique to the lens, it can be distributed on the market as lens data integrated with the lens, and the camera side is not necessarily described in the description of the present invention. There is an effect that the setup of the camera can be completed immediately just by attaching the lens without requiring a complicated setting operation.

[Brief description of the drawings]

FIG. 1 is a system diagram of an interchangeable lens camera according to the present invention.

FIG. 2 is an explanatory diagram of distortion of a lens used in the present invention.

[Explanation of symbols]

1 camera, 2 zoom lens, 7 nonvolatile memory lookup table for correction, 8 CCD, 9 DSP

Claims (3)

[Claims] 1. A method for correcting a difference between a reference pattern imaged via a camera and a distortion of an image output obtained from the camera by a correction means such as a digital signal processor to obtain a normal image output. A camera compatible with interchangeable lenses. 2. The interchangeable lens camera according to claim 1, wherein the distortion is corrected in conjunction with a lens state of a drive servo system of the zoom lens of the camera. 3. The camera according to claim 1, further comprising a storage unit for storing correction data in the lens body of the camera, wherein the correction data is transmitted to the camera when the lens body is mounted on the camera. 3. The interchangeable lens camera according to claim 1 or 2.