JP3685140B2 - Image reading method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading method, and more particularly to an image reading method for reading an image recorded on an exposed medium.
[0002]
[Prior art]
In the conventional image reading apparatus, a single frame image recorded on the film is first focused using a method of automatically adjusting the focus by regarding the state where the contrast of the image is maximum as the focused state. The Thereafter, the other frame images of the film are sequentially conveyed to the scanning position, each frame image is read, and image data is acquired.
[0003]
[Problems to be solved by the invention]
By the way, the width (up and down) dimension of the film transport groove in which both ends in the width direction of the film are guided when the film is transported is formed larger than the thickness dimension of the film. For this reason, when the film is transported and the next frame image is set to the scanning position, the film flutters in the film transport groove, resulting in variations in the position of the film surface to be focused. Further, when the next film is set, even if it is the same type of film, the position of the surface of the film to be focused similarly varies.
Therefore, even if the focus is adjusted accurately once, the focus is shifted every time the film is set, and the image cannot be read with high accuracy.
SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide an image reading method capable of acquiring highly accurate image data in which the influence due to the variation in the position of the surface of the exposed medium to be focused is reduced.
[0004]
[Means for Solving the Problems]
To achieve the above object, an image reading method according to claim 1, there is provided an image reading method reads an image recorded on the exposed medium, and focus adjustment each time to set the object to be exposed media plurality Acquiring a plurality of focus data from a plurality of exposure media , and a virtual focus between the two focus points among a plurality of focus points respectively corresponding to the plurality of focus data obtained from the plurality of exposure media. A step of obtaining virtual focus data corresponding to the virtual focus based on a plurality of focus data obtained from a plurality of exposed media , and a step of reading an image by adjusting a focus based on the virtual focus data.
Note that a plurality of focal points obtained by adjusting the focus each time an exposure medium is set are usually positioned on a straight line. The “focal points at both ends” referred to in claim 1 means two focal points located at both ends of the plurality of focal points located on a straight line. Further, “between the focal points at both ends” means that the positions of the focal points at both ends are included.
[0005]
The image reading method according to a second aspect is the image reading method according to the first aspect , wherein the plurality of focus data includes temperature data.
[0006]
Since the medium to be exposed fluctuates every time it is set, the position of the surface of the medium to be exposed to be focused will vary. In the image reading method according to the first aspect, the focus is adjusted every time the medium to be exposed is set, and a plurality of pieces of focus data are obtained from the plurality of mediums to be exposed . Then, the focus is adjusted based on the virtual focus data which is the calculation result of the plurality of focus data, and the image is read. As described above, the focus adjustment is performed in consideration of the occurrence of variations in the position of the surface of the medium to be exposed that is to be focused and fluttered every time it is set. Therefore, it is possible to obtain highly accurate image data in which the influence of the variation in the position of the surface of the medium to be exposed to be focused is reduced.
[0008]
In addition, for the second and subsequent exposed media, virtual focus data can be obtained by effectively using the focus data of the exposed medium that has been previously focus-adjusted , and the focus is adjusted one by one for each exposed medium. Even if it does just, it can acquire the above effects.
[0009]
In the image reading method according to the second aspect , it is possible to correct a focus shift caused by a change in an optical system such as a lens due to a temperature change. Therefore, even if there is a temperature change that causes a focus shift, it is possible to acquire high-precision image data without newly adjusting the focus.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Referring to FIG. 1, an image reading apparatus 10 using an image reading method according to an embodiment of the present invention includes a light source unit 12. The light source unit 12 emits light toward the film transport unit 14. In the film conveyance part 14, the film for photography which is an example of a to-be-exposed medium is conveyed, and the light emitted from the light source part 12 is irradiated to a film. A CCD unit 16 is disposed on the optical path of light emitted from the light source unit 12 and transmitted through the film of the film transport unit 14. The CCD unit 16 includes a sensor such as a line sensor. A lens unit 18 is disposed between the film transport unit 14 and the CCD unit 16. The lens unit 18 includes a lens (not shown) that can move along the optical axis L. The lens control unit 20 controls the lens unit 18 such as movement of the lens. The light transmitted through the film is projected onto the sensor of the CCD unit 16 through the lens unit 18.
[0011]
The CCD unit 16 further includes an A / D converter, converts light received by the sensor into image data that is digital data, and outputs the image data. The image data output from the CCD unit 16 is input to the image processing unit 22, subjected to predetermined processing, and further input to the display unit 26 such as a CRT via the system control unit 24 and recorded on the film. An image corresponding to the frame image is displayed on the display unit 26. The image processing unit 22 also outputs image data to an image output unit 28 which is a printing device, for example, and the image output unit 28 prints an image on, for example, photographic paper.
[0012]
Further, a data input unit 30 such as a keyboard is connected to the system control unit 24, and various data and the like are input from the data input unit 30. Further, the lens position information of the lens unit 18 is input to the system control unit 24 from the lens control unit 20, whereby the system control unit 24 recognizes the lens position. Further, the system control unit 24 controls the film transport unit 14 to transport the film, and controls the lens control unit 20 to move the lens of the lens unit 18. The system control unit 24 stores in advance a correction table for correcting the position of the lens using temperature data, as will be described later.
[0013]
The image data output from the CCD unit 16 is also input to the focus detection unit 32. The focus detection unit 32 determines the contrast of the image using the input image data, and the determined contrast is input to the system control unit 24 via the lens control unit 20 and stored.
[0014]
In the image reading apparatus 10, image data is acquired at each predetermined interval while the lens of the lens unit 18 is moved along the optical axis L, and the contrast is determined. Assuming a graph where the horizontal axis is the lens position and the vertical axis is the contrast value, the graph is chevron, and the position of the lens corresponding to the apex of the chevron (the point where the contrast is maximized) is focused most accurately. This is the matching lens position P _{m, n} (described later). In this way, the system control unit 24 calculates and obtains the lens position P _{m, n} that is in focus most accurately, and outputs information on the position P _{m, n} to the lens control unit 20. Further, the lens position P _{m, n that} is focused most accurately is stored in the system control unit 24 as focus data.
In this embodiment, for example, the position of the focal point is represented by a numerical value (for example, a numerical value of 0 to 10) that is larger as it is on the upper side and smaller as it is on the lower side, and the lens position P _{m, n} represents the position of the corresponding focal point. Expressed as a numerical value.
[0015]
The lens control unit 20 moves the lens of the lens unit 18 based on the focus data input from the system control unit 24. As a result, the focus is adjusted to achieve the most accurate focus.
A temperature sensor 34 is disposed in the vicinity of the lens unit 18. In the temperature sensor 34, the temperature data of the lens unit 18 is acquired, and the acquired temperature data is input to the system control unit 24 via the lens control unit 20, and is associated with the position of each lens as part of the focus data. Remembered.
[0016]
Next, main operations of the image reading apparatus 10 will be described with reference to FIGS. First, a variable m representing the number of films to be processed is set to 1 (step S1), and the number k of positions for determining the focal point for one film is input by an operator (step S3). ). Next, a variable n indicating the number of focus adjustments for one film is set to 1 (step S5), and the lens is placed at the initial position (step S7). Then, image data and temperature data used for focus adjustment are acquired (step S9), and the contrast of the image is determined using the acquired image data (step S11).
[0017]
Next, it is determined whether the lens has moved to a predetermined position (end point) set in advance (step S13). If the lens has not yet moved to the predetermined position, the lens is moved in the direction of the predetermined position (step S15). ), The process returns to step S9.
When the lens moves to a predetermined position, image data is acquired at a plurality of positions until the lens moves to the predetermined position, and the contrast of the image is determined. position P _{m of, n} are stored are determined as described above (step S17). Here, the position P _{m, n} is represented by a numerical value representing the position of the corresponding focal point as described above.
[0018]
Next, it is determined whether n = k is satisfied (step S19). If not, the film is conveyed by a predetermined distance so that a frame image different from the currently set frame image is arranged at the scanning position. (Step S21), 1 is added to the variable n (Step S23), and the process returns to Step S7. If n = k is satisfied, it is further determined whether m ≧ 2 is satisfied (step S25). If not, the process proceeds to step S27. If n = k, the process proceeds to step S37.
[0019]
When m ≧ 2 is not satisfied, that is, when the first film is processed (m = 1), the maximum value and the minimum value of the positions P _{1,1 to} P _{1, k} acquired at k positions of one film. An intermediate value {= (maximum value + minimum value) / 2} is calculated, and the lens is moved so that the position (virtual focus) corresponding to the intermediate value (virtual focus data) is in focus (step) S27). Then, a desired frame image is scanned (step S29), and highly accurate image data is acquired.
[0020]
Whether another film is to be processed is determined based on, for example, an operator's instruction (step S31). If no other film is processed, the operation is terminated. When processing another film, the film to be processed next is set in place of the film scanned in step S29 (step S33), 1 is added to the variable m (step S35), and the process proceeds to step S5. Return.
[0021]
If it is determined in step S25 that m ≧ 2 holds, that is, if the second and subsequent films are processed, the positions P _{1,1 to} P _{m, k} as the focus data are used for calculation in step S41 described later. The weight when it is set is set for each film (step S37). The weight is determined based on, for example, the passage of time or the type of film to be processed. Then, the values of the positions P _{1,1 to} P _{m, k} are corrected using the correction table based on the temperature data (step S39). More specifically, the current temperature of the lens unit 18 may be different from the temperature of the lens unit 18 when the positions P _{1,1 to} P _{m, k} are acquired in the past. The focus shift due to the difference is corrected by the correction table. The correction values of the positions P _{1,1 to} P _{m, k} corrected in step S39 are further corrected based on the weight set in step S37, and an intermediate value between the maximum value and the minimum value is calculated. Then, the lens is moved so that the position (virtual focus) corresponding to the intermediate value (virtual focus data) is in focus (step S41). Then, a desired frame image is scanned (step S43), and highly accurate image data is acquired.
[0022]
Whether another film is to be processed is determined based on, for example, an instruction from the operator (step S45), and the operation is terminated when no other film is processed. In the case of processing another film, the film to be processed next is set in place of the film scanned in step S43 (step S47), 1 is added to the variable m (step S49), and the process proceeds to step S5. Return.
In the image reading apparatus 10, the focus is accurately adjusted as described above, and highly accurate image data is acquired.
[0023]
According to the image reading device 10, each time a film is set, the focus is adjusted to obtain a plurality of focus data, and the focus is adjusted based on the calculation result of the plurality of focus data, and the image is read. High-accuracy image data in which the influence of variations in the position of the surface of the power film is reduced can be acquired. Specifically, among the multiple focal points obtained each time the film is set, the focal point is an intermediate position between the uppermost focal point and the lowermost focal point, that is, the average position of the surface of the film to be focused. Since the lenses are set so as to match each other, the defocus width is reduced, and highly accurate image data can be acquired regardless of which frame image is read.
[0024]
When a plurality of focus data is acquired from one film and the focus is adjusted, the focus is accurately adjusted even in the first film, and highly accurate image data can be acquired.
In addition, for the second and subsequent films, it is possible to use the focus data of the film that was previously adjusted in focus, so that it is possible to accurately adjust the focus as described above by simply adjusting the focus for each film. . Therefore, the focus can be adjusted quickly.
[0025]
The focus data includes the temperature data of the lens unit 18 and is calculated using the correction values of the positions P _{1,1 to} P _{m, k} corrected using the temperature data and the correction table, and the lens is moved. Therefore, the focus can be adjusted in consideration of a focus shift caused by a change in temperature of an optical system such as a lens. Therefore, the focus can be adjusted more accurately.
[0026]
Incidentally, in step S27 and step S41, the position P _{m, 1} to P m, instead of obtaining an intermediate value between the maximum value and the minimum value of the values of _k, position P _{m, 1} to P m, the value of _k An average value may be obtained.
In the case of processing a plurality of films, even if k = 1, that is, focus data is acquired at one place for each film, the above-described effects can be obtained for the second and subsequent films.
Furthermore, even when adjusting the focus of the second and subsequent films, it is possible to adjust the focus using only the focus data acquired for each individual film without using the focus data of the previously adjusted film. Good. In this case, it is preferable to acquire focus data at a plurality of positions for each film.
[0027]
In addition, when using the focus data of a film whose focus has been adjusted previously, only the latest predetermined number (for example, 10) of film focus data is always used. You may make it do.
Furthermore, past data such as when the temperature of the lens unit 18 or the like changes greatly (for example, 10 degrees to 20 degrees) due to a long elapsed time since the previous focus adjustment, or when the type of film to be processed is different. If it is difficult to use, the focus data is newly acquired at a plurality of positions as the first film without changing the weighting accordingly or using the focus data for the previously processed film. You may adjust the focus.
[0028]
Further, once the focus adjustment is performed as described above, and until the next focus adjustment, the temperature data of the lens unit 18 acquired by the temperature sensor 34 and the correction table stored in the system control unit 24 are stored. The lens position may be corrected so as to correct the focus shift due to the temperature change. Even if there was a temperature change that would cause a focus shift in the past, if the temperature was compensated as described above, the image was accurately focused without newly adjusting the focus, and high-accuracy image data was acquired. can do. Therefore, in continuous processing for a long time, the focus is always accurately adjusted even if the number of times of focus adjustment is small, so that the efficiency of the image reading process is improved. In addition, accurate focus adjustment can be reproduced even when there is a temperature change. Furthermore, since the focus adjustment and the temperature compensation considering the variation of the surface of the film to be focused are used in combination, the accuracy is further improved as compared with the case where the temperature compensation is performed alone.
Moreover, the medium to be exposed includes a negative film and a positive film.
[0029]
【The invention's effect】
According to the present invention, it is possible to acquire highly accurate image data in which the influence due to the variation in the position of the surface of the medium to be exposed to be focused is reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an image reading apparatus using an embodiment of the present invention.
FIG. 2 is a flowchart showing an example of the operation of the present invention.
FIG. 3 is a flowchart showing a continuation of the operation shown in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image reader 14 Film conveyance part 16 CCD unit 18 Lens unit 20 Lens control part 24 System control part 32 Focus detection part 34 Temperature sensor

Claims (2)

An image reading method for reading an image recorded on an exposed medium,
A step of acquiring a plurality of focus data from a plurality of exposed media by adjusting the focus each time the exposed medium is set;
Among a plurality of focal points corresponding to the plurality of focus data obtained from the plurality of the exposed medium, as a virtual focal point located between the focal point of both ends, the virtual focus data corresponding to the virtual focal point An image reading method comprising: a step of obtaining based on the plurality of focus data obtained from a plurality of exposure media ; and a step of reading the image by adjusting a focus based on the virtual focus data. The image reading method according to claim 1 , wherein the plurality of focus data includes temperature data.

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