JPH06250276A - Camera system - Google Patents

Abstract

PURPOSE:To provide a camera system composed of a compact light-weight camera and an image processor for obtaining an image not having peripheral dimming. CONSTITUTION:The camera system is composed of a camera 1, a film 10 provided with a magnetic tape 11, the image processor 12 and a color printer 18 and the camera 1 previously selects peripheral dimming data recorded in a ROM 5 from lens information in each frame at the time of photographing and records the peripheral dimming data on the magnetic tape 11. At the time of outputting, the image processor 12 reads out the peripheral dimming data from the magnetic tape 11 by a peripheral dimming data reading part 14 and the peripheral dimming of the image stored in a frame memory 16 is corrected by using the peripheral dimming data and transferred to a frame memory 17, to output the corrected image by the color printer 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system, and more particularly to a camera system for obtaining an image without peripheral dimming.

[0002]

2. Description of the Related Art Generally, the brightness of a camera lens is f
This is determined by the number, but this indicates the brightness of the image (center of the image) formed on the optical axis of the lens. The brightness of the peripheral part of the image with respect to the brightness of the center of this image,
That is, the illuminance of the peripheral portion of the image is called the peripheral light amount.

When the lens is opened, the amount of peripheral light is affected by vignetting and the fourth power law of cos, and the illuminance is reduced.
The illuminance is reduced due to the influence of the cos fourth law. Hereinafter, this decrease in illuminance will be referred to as peripheral dimming. In this way, the peripheral dimming of the image at the time of shooting produces a photograph in which the peripheral portion is dark. Generally, it is basically designed so that the image pickup lens system of a camera is reduced in peripheral dimming.

In order to prevent this peripheral dimming, for example, there is a technique proposed in Japanese Patent Application Laid-Open No. 63-26079 for correcting unevenness in the light amount of an image by image processing.

[0005]

However, from the viewpoint of a certain lens system, it is very difficult to design such that the peripheral dimming does not always occur with an arbitrary lens arrangement and an arbitrary diaphragm. Further, since the peripheral extinction is corrected, there is a drawback that the configuration of the lens system becomes complicated and the weight and volume of the camera itself increase. An object of the present invention is to provide a camera system including a small and lightweight camera and an image processing device for obtaining an image without peripheral dimming.

[0006]

In order to achieve the above object, the present invention comprises a camera having means for recording photographing information related to peripheral dimming together with an image, and means for reading the photographing information and the image. There is provided a camera system including an image output device having an output unit that corrects and outputs the peripheral extinction of the image using the read shooting information.

[0007]

With the camera system having the above-described structure, peripheral dimming of an image is corrected using information for each frame at the time of shooting, and an image taken at an arbitrary aperture, an arbitrary focal length, and an arbitrary focal position is corrected. The peripheral dimming of is corrected. Further, it is not necessary to correct the peripheral dimming by the imaging lens itself.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2, the configuration of a camera system as a first embodiment according to the present invention will be shown and described.

FIG. 2 is a diagram showing the flow of information and the schematic structure of the camera system according to the present invention. A camera 1 capable of recording peripheral dimming data of a lens at the time of photographing, a film 10 having a magnetic tape 11 for recording information, an image processing device 12 capable of reading information, and outputting an image. And a color printer 18 for FIG. 1 shows a specific configuration of this camera system.

In this camera system, the camera 1
Is a lens 3 having a variable focal length and focal position, a drive unit 4 for changing the focal length and focal position of the lens 3, and a ROM 5 in which peripheral dimming data of the lens 3 is recorded in advance. , A distance measuring unit 6 for measuring the distance to the subject, an exposure control unit 7 for measuring the brightness of the subject and controlling the exposure, a release button 8, and peripheral dimming data at the time of shooting are recorded on the magnetic tape 11. The peripheral dimming data writing unit 9 for controlling the peripheral dimming data, the ROM 5, the ROM 5, the distance measuring unit 6, the exposure control unit 7, and the CPU 2 for controlling the peripheral dimming data writing unit 9.

The image processing apparatus 12 also includes a peripheral dimming data reading section 14 for reading the peripheral dimming data recorded on the magnetic tape 11, a film scanner 15 for reading an image from the film 10, and the film. A frame memory 16 for recording an image read by the scanner 15, the film scanner 15,
The CPU 13 controls the CPU 14 and the frame memory 17 for recording the image of which the peripheral dimming is corrected by the CPU 13. The corrected image data stored in the frame memory 17 is output to a photograph or the like by the existing color printer 18. Next, the operation of the camera 1 in the camera system thus configured will be described with reference to the flowchart of FIG.

First, after the sequence start is started by turning on the main switch of the camera 1, it is judged whether the fast release is turned on or off by the photographer (step S1). When the fast release is turned on (YES), the exposure control section 7 performs photometry. This is performed (step S2), and then the distance measuring unit 6 measures the distance (step S3). The aperture value is determined based on the result of the distance measurement, the lens is driven by the lens driving unit 4, and the autofocus is completed (step S4).

Further, it is judged whether the second release is turned on or off by the photographer (step S5), and when it is turned on (YE
S), exposure is performed with the diaphragm lens arrangement determined in steps S2 to S4 (step S6). Then C
The PU2 determines the lens information (focal length, focus position and diaphragm) at the time of shooting (step S7), and the lens information is converted into peripheral dimming data using the data in the ROM 5 built in the lens ( Step S8).

The converted peripheral extinction data is then written on the magnetic tape 11 by the peripheral extinction data writing section 9 (step S9). Further, the photographer determines whether or not to end the photographing (step S10). To continue shooting (NO), feed the film (step S11),
Return to step S1. However, when the photographer finishes photographing (YES), this sequence ends. here,
The peripheral dimming data necessary for the peripheral dimming data conversion in step S8 will be described. If the real image brightness on the film surface is b and the ideal image brightness is b ', the magnitude D of peripheral extinction is expressed by the following equation (1). D = (bb ′) / b ′ × 100 (%) (1)

Assuming that the peripheral extinction is a function of the image height, the peripheral extinction curve shown in FIG. 4A is obtained when the horizontal axis represents the real image height z and the vertical axis represents the peripheral extinction D. In this embodiment, in order to keep the capacity of the ROM 5 small, the peripheral dimming data is actually limited to five points shown on the curve of FIG. 4A, and as shown in FIG. It is approximated by a peripheral extinction line composed of a polygonal line connecting five points of peripheral extinction data. next,
A specific format of peripheral dimming data in the ROM 5 will be described. The ROM 5 has two tables such as Table 1 and Table 2 according to various lenses and their aperture values.

[0016]

[Table 1]

[0017]

[Table 2]

Table 1 is a table in which the lens information ("focal length" f and "focal position" d) determined by the CPU 2 is divided into nine groups according to their values. Since peripheral dimming generally changes depending on the focal length or focal position of the same lens, it is necessary to change the peripheral dimming data depending on the focal length or focal position. This grouping is performed in consideration of the change rate of the peripheral extinction depending on the focal length and the focus position, that is, the large changes in the peripheral extinction are fine and the small changes are roughly divided. Table 2 is a conversion table for converting the lens information n grouped in Table 1 into the peripheral extinction data D _{1 to} D ₅ .

FIG. 5 is a flow chart showing the sequence of the "peripheral dimming data conversion" subroutine in which the peripheral dimming data of step S8 of FIG. 3 is converted and read from the ROM 5.

First, after the sequence is started, in the lens information judged in step S7 of FIG.
An appropriate conversion table is selected from a plurality of conversion tables stored in the ROM 5 according to the "lens type" and the "aperture" (step S21).

Next, lens information "focal length" f at the time of shooting
And "focus position" d are grouped according to Table 1 (step S22). The lens information n divided into groups is the peripheral dimming data D _{1 to} D according to the conversion table of Table 2.
_It is converted to ₅ (step 23), and this sequence ends. The operation of the image processing apparatus 12 will be described with reference to the flowchart shown in FIG. Here, the reference numerals of the constituent members are the same as those shown in FIG.

First, after the sequence is started, the image recorded on the film 10 is read by the film scanner 15 (step S31), and the frame memory 1 is read.
6 is transferred (step S32).

Next, the peripheral extinction data recorded on the magnetic tape 11 is read by the peripheral extinction data reading section 14 (step S33). Then the CPU
The peripheral dimming data of the image stored in the frame memory 16 is corrected using the read peripheral dimming data (step S34) and transferred to the frame memory 17 (step S35). Then, the corrected image is output by the color printer 18 (step S3).
6) Then, this sequence ends.

The peripheral dimming correction of step S34 shown in FIG. 6 will be described with reference to the flowchart of the subroutine for correcting the peripheral dimming of the image using the peripheral dimming data shown in FIG.

[0025] First, after sequence start, all vignette data D ₁ ~D ₅ "0" whether determined if it is determined (step S41), are all "0" (YES), The peripheral dimming correction is not performed, and this sequence ends. However, if it is determined that even one of D _{1 to} D ₅ is not "0" (NO), the correction is calculated (step S42), and the present sequence is ended. Next, a specific method of the correction calculation of step S42 shown in FIG. 7, that is, the peripheral dimming correction will be described.

First, when the peripheral extinction data D _{1 to} D ₅ are given, an approximate curve of peripheral extinction is obtained. This is formula (1)
As described above, the ratio of the peripheral extinction of the real image height to the ideal image height is represented. When this equation is solved for the ideal luminance d ′, b ′ = (1 + D / 100) b (2) That is, b ′ is obtained by multiplying b by (1 + D / 100).

In the present embodiment, the image is read from the film 10, but the read image is a discrete digital image. In this case, the real image height z corresponds to a pixel located at a distance z from the center of the image. Therefore, in order to correct the peripheral dimming, the distance z from the center of the image
The brightness b of the distant pixel of interest is the brightness b ′ obtained by the equation (2).
Should be replaced with

With the above configuration, it is not necessary to correct the peripheral dimming by the image pickup lens itself, and the lens configuration can be simplified. Further, it becomes possible to perform peripheral dimming correction at an arbitrary focal length and focal position, and it is possible to provide a higher quality photograph.

FIG. 8 shows the structure of a camera system as a second embodiment according to the present invention, which will be described. Where the second
The same members as the members shown in FIG. 1 of the embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this camera system, as in the first embodiment, a camera 21 capable of recording peripheral dimming data of a lens at the time of photographing, a film 29 provided with a magnetic tape 30 for recording information, Image processing device 3 for reading information
1 and a color printer 3 for outputting a corrected image
8 and.

The configuration of the second embodiment differs from the configuration of the first embodiment in that the ROM 5 in the first embodiment does not correspond to the ROM 5 in the configuration of this embodiment, and the peripheral dimming data writing is performed. The lens information writing unit 28 and the lens information reading unit 33 correspond to the unit 9 and the peripheral dimming data reading unit 14, respectively, and further, the image processing apparatus 31 includes the ROM 36. The ROM 36 stores peripheral dimming data corresponding to a plurality of lenses used for photographing. Next, the operation of the camera 21 of the camera system of the second embodiment described above will be described with reference to the flowchart shown in FIG.

First, after the sequence start is started by turning on the main step of the camera, the photographer determines whether the fast release is on or off (step S51). When the fast release is turned on (YES), the exposure controller 7 performs photometry. I (step 52), and then the distance measuring unit 6 measures the distance (step S53). The aperture value is determined based on the result of the distance measurement, the lens is driven by the lens driving unit 4, and the autofocus is completed (step S54).

Next, it is determined whether or not the second release is turned on / off by the photographer (step S55). If the second release is turned on (YES), exposure is performed with the aperture lens arrangement determined in steps S52 to S54 (step). S56).
Subsequently, the CPU 2 determines the lens information (lens type, focal length, focal position, diaphragm) at the time of shooting (step S57), and the lens information is written on the magnetic tape 30 by the lens information writing unit 28. (Step S58).

Next, it is determined whether the photographer finishes photographing (step S59). If the photographer continues shooting (NO), the film is fed (step S60) and the process returns to step S51. When the photographer finishes shooting, this sequence ends. Next, the operation of the image processing device 31 will be described with reference to the flowchart shown in FIG.

First, after the sequence is started, the image recorded on the film 29 is displayed on the film scanner 3.
4 is read (step S61) and transferred to the frame memory 35 (step S62).

Next, the lens information recorded on the magnetic tape 30 is read by the lens information reading section 33 (step S63). Then, the CPU 32 converts the lens information into peripheral dimming data using the data stored in the ROM 36 (step S6).
4) The peripheral dimming of the image stored in the frame memory 35 is corrected using the converted peripheral dimming data (step S65).

Then, the corrected image is transferred to the frame memory 37 (step S66). Further, the color printer 38 outputs the corrected image to the printer (step S67), and this sequence ends. Next, the flowchart of FIG. 11 is the subroutine of step S64 shown in FIG. 10, that is, the peripheral dimming data conversion.

This peripheral dimming data conversion will be described. First, after the sequence start, by the "lens type" and "aperture" in the read lens information,
An appropriate conversion table is selected from the plurality of conversion tables stored in the ROM 32 (step S7).
1). Next, in the read lens information at the time of shooting,
The "focal length" and "focal position" are grouped according to the conversion table selected in step S71 (step S71).
72), grouped lens position information n is converted into limb darkening data D ₁ to D ₅ (step S7
3), this sequence ends.

In the embodiment of the present invention, the peripheral dimming data is represented by 5 pieces of data, but it may be represented by more or less data. Further, the peripheral extinction curve may be expanded and its coefficient may be used as the peripheral extinction data.

With the above configuration, since the peripheral dimming of the image is corrected using the information for each frame at the time of shooting, it is possible to obtain an image in which the peripheral dimming is corrected at an arbitrary focal length, focal position and diaphragm. it can. Further, in the present embodiment, the lens information of the peripheral dimming data is recorded for each frame, but it is temporarily recorded in a recording medium such as another semiconductor memory, and when rewinding after completion of shooting, You may record collectively at once. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[0041]

As described in detail above, according to the present invention, it is not necessary to correct the peripheral dimming by the image pickup lens itself, and an image without peripheral dimming can be obtained by a small and lightweight camera having a simplified lens structure. It is possible to provide a camera system for obtaining the information.

[Brief description of drawings]

FIG. 1 is a block diagram showing a specific configuration of a camera system as a first embodiment according to the present invention.

FIG. 2 is a diagram showing a flow of information and a schematic configuration of a camera system according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the camera in the camera system shown in FIG.

FIG. 4 (a) shows a peripheral extinction curve, and FIG.
(B) is a figure which shows the peripheral dimming light which connected arbitrary peripheral dimming data with a polygonal line.

FIG. 5 is a flowchart showing a sequence of peripheral dimming data conversion of FIG.

FIG. 6 is a flowchart for explaining the operation of the image processing apparatus.

FIG. 7 is a flowchart of a subroutine for correcting the peripheral dimming of an image by using the peripheral dimming data.

FIG. 8 is a diagram showing a configuration of a camera system as a second embodiment according to the present invention.

9 is a flowchart for explaining the operation of the image processing apparatus shown in FIG.

FIG. 10 is a flowchart for explaining the operation of the image processing apparatus shown in FIG.

11 is a flowchart of a subroutine for performing peripheral dimming data conversion of FIG.

[Explanation of symbols]

1 ... Camera, 2 ... CPU, 3 ... Lens, 4 ... Lens drive section, 5 ... ROM, 6 ... Distance measuring section, 7 ... Exposure control section, 8 ... Release button, 9 ... Peripheral dimming data writing section, 10 ... Film, 11 ... Magnetic tape, 12 ... Image processing device, 13
... CPU, 14 ... Peripheral dimming data reading section, 15 ... Film scanner, 16, 17 ... Frame memory, 18 ... Color printer.

Claims (1)

[Claims] 1. A camera having a unit for recording photographing information related to peripheral dimming together with an image, a unit for reading the photographing information and the image, and a unit for reading the image by using the read photographing information. An image output device having an output unit that corrects and outputs ambient light reduction.