JP2003295328A - Image reader and focusing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader and a focusing control method for focusing on a specified area in an image with high precision. <P>SOLUTION: On a film 16, a plurality of positions for obtaining focus data are set first. Then an area to preferentially be focused on in the frame image of the film 16 is set. The area is set including the plurality of positions for obtaining the focus data. According to pieces of focus data obtained in the area to preferentially be focused on, virtual focus data are obtained. According to the virtual focus data, the lens of a lens unit 22 is moved to focus on the frame image, and a CCD unit 20 reads the frame image. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus and a focusing control method, and more particularly to an image reading apparatus and a focusing control method for focusing an image recorded on an exposed medium.

[0002]

2. Description of the Related Art Some films on which an image is recorded have a warp. If the film has a warp, the position of the film surface to be focused becomes non-uniform, and the focus cannot be accurately controlled, which is a problem. This is more pronounced in mounted films compared to sleeve films. With respect to such a problem, Japanese Patent Laid-Open No. 2000-89
374 discloses a technique for obtaining a focused state with a small shift amount in the entire image by focusing on an intermediate position of a plurality of focal points obtained by controlling the focusing at a plurality of positions of the image. . With this technique, the entire target frame image (or film) is focused.

[0003]

However, Japanese Patent Laid-Open No. 2000-2000
The technique of -89374 is not suitable when high-precision focusing is required for only a part of the frame image, such as when trimming an image. This is because if the whole frame image is focused, it cannot be said that the image is focused with high accuracy when focusing on the image of the required specific area. Therefore, a main object of the present invention is to provide an image reading apparatus and a focusing control method capable of focusing a specific area in an image with high accuracy.

[0004]

In order to achieve the above-mentioned object, an image reading apparatus according to claim 1 is an image reading apparatus for reading an image recorded on an exposed medium, and the image is recorded on the exposed medium. A light source that emits light toward an image forming unit, an image forming unit that forms an image of light that has passed through an exposed medium or light reflected from the exposed medium, an image sensor that detects the image formed by the image forming unit, and reads an image, an image Setting means for setting a desired region therein, at least a part of the image forming means, moving means for moving at least one of the image sensor and the medium to be exposed in the optical axis direction of the image forming means, and the setting means. Virtual focus data is obtained based on a plurality of focus data obtained for a plurality of positions in the region, and at least a part of the image forming means is provided at a position based on the virtual focus data.
Control means is provided to control the moving means so that at least one of the image sensor and the medium to be exposed moves.

According to a second aspect of the focus control method, a step of setting a desired area in an image recorded on an exposed medium,
The method includes a step of acquiring focus data at each of a plurality of positions in at least an area, a step of acquiring virtual focus data based on the plurality of focus data, and a step of focusing an image on the basis of the virtual focus data.

In the image reading apparatus according to the first aspect, a desired area in the image is set, focus data is obtained at each of a plurality of positions in the set area, and the focus data is obtained based on the plurality of focus data. The focus is adjusted based on the virtual focus data. Therefore,
Even if you want to preferentially focus on a specific area in the image, for example, when trimming the image or when you want to focus preferentially on the face of a person included in the image, the warpage of the exposed medium Focusing can be performed with high accuracy by reducing the influence of. The same applies to the focus control method according to claim 2.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Referring to FIGS. 1 and 2, an image reading device 10 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 transport unit 14, a photographic film 16 which is an example of an exposed medium is set and transported as needed, and the light emitted from the light source unit 12 is applied to the film 16. In this embodiment, the film 16 mounted on the film mount 18 is used.

The film transport section 1 is emitted from the light source section 12.
The CCD unit 20 is arranged on the optical path of the light transmitted through the film 16 of No. 4. The CCD unit 20 includes a sensor such as a line sensor. A lens unit 22 is arranged as an image forming means between the film transport unit 14 and the CCD unit 20. The lens unit 22 includes a lens (not shown) that can move along the optical axis L. The lens control unit 24 controls the lens unit 22 such as the movement of the lens. The light transmitted through the film 16 is projected onto the sensor of the CCD unit 20 via the lens unit 22.

The CCD unit 20 further includes an A / D converter and converts the light received by the sensor into image data which is digital data and outputs it. The image data output from the CCD unit 20 is input to the image processing unit 26. The image processing unit 26 performs predetermined processing such as gradation conversion and color conversion. The image data output from the image processing unit 26 is further input to a display unit 30 such as a CRT via a system control unit 28 which is a control unit, and an image corresponding to the frame image recorded on the film 16 is displayed on the display unit 30. Is displayed in. The image processing unit 26 also outputs image data to an image output unit 32, which is, for example, a printing device, and the image output unit 32 prints the image on photographic paper, for example.

Further, an input unit 34 such as a keyboard and a mouse is connected to the system control unit 28, and various settings and data input are performed from the input unit 34. Further, position information of the lens of the lens unit 22 is input to the system control unit 28 from the lens control unit 24, so that the system control unit 28 recognizes the position of the lens. further,
The system control unit 28 controls the film transport unit 14 to transport the film 16 as needed, and the lens control unit 24
Is controlled to move the lens of the lens unit 22.
The image data output from the CCD unit 20 is also input to the focus detection unit 36. Focus detector 3
In 6, the contrast of the image is determined using the input image data, and the determined contrast is input to and stored in the system control unit 28.

In the image reading apparatus 10, the lens unit 2
While the second lens is moved along the optical axis L, image data is acquired at each position at predetermined intervals, and the contrast is determined for each. Assuming a graph in which the horizontal axis is the position of the lens and the vertical axis is the value of contrast, the graph becomes a mountain shape, and the position of the lens corresponding to the apex of the mountain shape (the point where the contrast becomes maximum) is the most accurate focus. The position of the lens to be fitted, that is, the focus position P _{m, n} (described later). In the system control unit 28, the focus position P
_{m and n} are calculated and stored as focus data.

In this embodiment, for example, the lens control unit 24 includes a pulse motor for moving the lens of the lens unit 22, and the focus position P _{m, n} is the moving distance (pulse) from the mechanical origin of the lens. The number of motor pulses). The system control unit 28 further obtains virtual focus data based on the focus data as described later. The virtual focus data obtained by the system control unit 28 is output to the lens control unit 24.

The lens controller 24 is a system controller 28.
The lens of the lens unit 22 is moved based on the virtual focus data input from. As a result, focus adjustment is performed so that the image forming position of the lens unit 22 and the position of the sensor of the CCD unit 20 coincide with each other, that is, the focus is adjusted accurately. A temperature sensor 38 is arranged near the lens unit 22. The temperature sensor 38 acquires the temperature data of the lens unit 22, and the acquired temperature data is input to the system control unit 28 via the lens control unit 24 and stored in association with the position of each lens. The system control unit 28
The position of the lens can be adjusted based on the temperature data.

Next, the main operation of the image reading apparatus 10 will be described with reference to FIGS. 3 and 4. First, a plurality of positions in the film 16 for acquiring focus data are set (step S1). In this embodiment, for example, 25 positions (positions indicated by ◯ in FIG. 2) that are evenly arranged in a 5 × 5 matrix on the frame image of the film 16 are set. Here, the focus position (focus data) at each position is represented as P _{m, n} . It is assumed that m represents a column and n represents a row. For example, in FIG. 2, the focus position at the upper left position is P _1,1 and the focus position at the upper right position is P _5,1 and the lower left position is P _5,1 . The in-focus position at the position is P _1,5
Then, the focus position at the lower right position is represented as P _5,5 .

Next, a region to be focused preferentially, such as a region to be trimmed or a region to be focused preferentially (for example, a person's face), is set at a desired position in the frame image on the film 16. (Step S3). The size of the area is arbitrarily set as long as a plurality of positions set in step S1 are included. In this embodiment, for example, a region near the center of the film 16 (a region surrounded by a chain double-dashed line F in FIG. 2) is set, and the focus positions P _{2,2 to} P _4,2 , P ₂ are set in this region. _, 3 to P _4,3, it contains nine positions P _2,4 ~P _{4, 4} is obtained. Then, the lens is arranged at the initial position (step S5), and image data used for focus adjustment is acquired (step S5).
7) The contrast of the image is determined using the acquired image data (step S9).

Next, it is judged whether the lens has moved to a predetermined position (end point) set in advance (step S1).
1) If the lens has not yet moved to the predetermined position, the lens is moved in the direction of the predetermined position (step S13) and the process returns to step S7. When the lens moves to a predetermined position, image data is acquired at each of a plurality of positions until the lens moves to the predetermined position, and the contrast of the image is determined, and the contrast becomes the maximum from the value of the contrast. The position of the lens is obtained as described above and stored as the focus position P _{m, n} (step S1).
5).

Then, it is determined whether or not the in-focus position P _{m, n,} that is, the focus data has been acquired at all the positions set in step S1 (step S17). If NO is determined, the focus data is acquired. The film 16 is transported so that another scheduled position is located at the scanning position (step S19), and the process returns to step S5.

If YES is determined in step S17, virtual focus data is acquired based on a plurality (9 in this embodiment) of focus data acquired in the area set in step S3 ( Step S2
1). For the virtual focus data, for example, step S
An intermediate value {= (maximum value + minimum value) / 2} between the maximum value and the minimum value of the plurality of focus data acquired in the area set in 3 is set. Then, the lens of the lens unit 22 is moved based on the virtual focus data (step S23), and the frame image of the film 16 is scanned (step S25). As a result, image data such as an image trimmed from the frame image of the film 16 or an image in which a desired area is preferentially focused is acquired.

Further, it is judged based on, for example, an operator's instruction whether another image such as a frame image of another film or another frame image of the same film should be processed (step S27), and the other image is not processed. If so, the operation is terminated. When processing another image, an image to be processed next is set instead of the image scanned in step S25 (step S29), and the process returns to step S1.

According to the image reading apparatus 10, the film 16
Since the focus data is obtained at a plurality of positions on the frame image, the warped state of the film 16 is recognized. Then, a desired area in the frame image of the film 16 is set, virtual focus data is obtained based on the focus data acquired at a plurality of positions in the set area, and focus adjustment is performed based on the virtual focus data. It Therefore, for example, when trimming an image or when preferentially focusing on the face of a person in the image,
When preferentially focusing on a specific area in the image, compared to the conventional case where the entire frame image is focused, the influence of the warp of the film 16 is reduced to achieve high precision focusing. Can be charred. Therefore, it is possible to obtain highly accurate image data that is preferentially focused on a particularly important area such as trimming.

It is also possible to set the area to be focused preferentially, and then obtain the focus data at a plurality of positions within the area. According to this, the position (the number of times) at which the focus data is acquired is reduced as compared with the case of the above-described embodiment, and the desired area can be quickly focused. The area to be preferentially focused may not be set for each image to be scanned as described above, but may be set at a predetermined position (for example, near the center of the image) in advance.

Further, a plurality of areas to be preferentially focused may be set. By doing so, for example, the faces of a plurality of persons in the image can be focused preferentially.
In this case, the virtual focus data may be obtained based on the plurality of focus data acquired in the plurality of areas. Further, the virtual focus data may be an average value of the plurality of acquired focus data.

Further, if there is a position where focus data cannot be acquired because the contrast cannot be determined, such as when the image is too dark, an approximate value obtained based on the focus data at a nearby position is used as the focus data at that position. Good. As the approximate value, for example, the average value of the focus data on both sides is used. If the position where the focus data cannot be obtained is the edge of the frame image,
As the approximate value, for example, a value at a corresponding position on the extension line of the curve of the graph showing the contrast is used.

Further, focus adjustment is not limited to moving the lens of the lens unit 22 in the optical axis L direction, and a motor for moving the entire lens unit 22 is provided to move the entire lens unit 22, or C
A motor for moving the CD unit 20 is provided to move the CCD unit 20 or the film 16, and at least a part of the lens unit 22 and the CCD unit 2 are moved.
The focus may be adjusted by moving at least one of 0 and the film 16 in the optical axis L direction.

Further, the lens unit 22 may form an image of the light reflected from the film 16. The medium to be exposed is not limited to the film 16 mounted on the film mount 18, and may be a sleeve film, or may be a negative film or a positive film.

[0026]

According to the present invention, even when it is desired to focus on a specific area in an image with priority, it is possible to reduce the influence of the warp of the medium to be exposed and focus with high accuracy. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an illustrative view showing a plurality of positions for obtaining focus data on a mounted film.

FIG. 3 is a flowchart showing an example of the operation of the present invention.

FIG. 4 is a flowchart showing a continuation of the operation shown in FIG.

[Explanation of symbols]

10 Image reading device 12 Light source 14 Film transport section 16 films 20 CCD unit 22 Lens unit 24 Lens control unit 28 System control unit 34 Data input section 36 Focus detector

Claims (2)

[Claims] 1. An image reading apparatus for reading an image recorded on an exposed medium, wherein the light source emits light toward the exposed medium, light transmitted through the exposed medium or reflected from the exposed medium. At least one of an image forming unit that forms an image of light, an image sensor that detects the image formed by the image forming unit and reads the image, a setting unit that sets a desired area in the image, and the image forming unit. Section, the image sensor, and at least one of the exposed medium in the optical axis direction of the image forming means, and a plurality of positions in the area set by the setting means. Virtual focus data is obtained based on a plurality of focus data, and at least a part of the image forming unit, the image sensor and the exposed medium are provided at a position based on the virtual focus data. At least one of a control means for controlling said moving means to move the image reading apparatus of the. 2. A step of setting a desired area in an image recorded on an exposed medium, a step of acquiring focus data at each of a plurality of positions in the area, and virtual focus data based on the plurality of focus data. And focusing the image based on the virtual focus data.
Focus control method.