JP2001007988A - Film read method and film reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a print image with high quality by a 2nd visual range optical sensor reading a visual area light different from a read wavelength band of a 1st visual area optical sensor so as to sense dust or a flaw of a film. SOLUTION: A scanner 11 applies primary reading (preliminary scanning) to a film by using RGB and 'GR' lights. A histogram of obtained preliminary scanning image data RGB and 'GR' is calculated and a threshold value for dust/flaw discrimination is calculated. After the preliminary scanning, two thresholds Dth1, Dth2 are calculated for the discrimination, the scanner 11 conducts the fine scanning by using the RGB and 'GR' light. A new threshold Dth3=f(DR.DG) is generated for each pixel by using a value like a function approximation for a density (DR) of a R and a density (DG) of G for polynomial approximation, and in the case that the fine scanning DRG (density of GR) is higher than the Dth3, presence of dust/flaw can be discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film reading method and a film reading apparatus, and more particularly, to detecting a dust / scratch in a film reading apparatus.
The present invention relates to a film reading method which can be performed by visible light and a film reading apparatus to which the method is applied.

[0002]

2. Description of the Related Art Conventionally, printing an image photographed on a photographic film (hereinafter, also simply referred to as a film) such as a negative film or a positive film (reversal film) onto a photographic paper is performed by projecting the image of the film onto the photographic paper. What is called direct exposure (analog exposure), which exposes photographic paper to the surface, has been the mainstream, but in recent years, printing apparatuses that use digital exposure,
That is, the image of the film is photoelectrically read, the read image is converted into a digital signal, and then subjected to various image processing to obtain image data for recording, and the photographic paper is scanned with recording light modulated according to the image data. 2. Description of the Related Art Digital printers that record images by exposure have been put to practical use.

In a digital printer, an image is converted into digital image data, and the exposure conditions at the time of printing are determined by image data processing. It is possible to obtain a high-quality print which could not be obtained by the conventional direct exposure by suitably performing (sharpening) processing, correcting color or density feria, and the like. Also, synthesis of a plurality of images, image division, and synthesis of characters can be performed by image data processing, and a print that has been freely edited / processed according to the intended use can be output.

[0004] Such a digital printer basically includes a scanner (image reading device) for photoelectrically reading an image recorded on a film, and image data for output by processing the image read by the scanner. An image input device having an image processing device that sets exposure conditions), a printer that scans and exposes photographic paper according to image data output from the image input device to record an image (latent image), and And an image output device having a processor that performs development processing on photographic paper to produce a print.

In the above-described scanner, reading light emitted from a light source is made incident on a film to obtain projection light carrying an image on the film, and this projection light is converted into a C light by an imaging lens.
An image is read by forming an image on an image sensor such as a CD sensor and photoelectrically converting the image, performing various types of image processing as necessary, and then sending the image data (signal) of the film to an image processing apparatus. The image processing apparatus sets image processing conditions from image data read by the scanner,
The image processing is performed according to the set conditions, and is sent to the printer as output image data for image recording.

In a printer, for example, if the apparatus uses light beam scanning exposure, the light beam is modulated in accordance with image data sent from an image processing apparatus, and the light beam is deflected in the main scanning direction. By transporting the printing paper in a sub-scanning direction orthogonal to the main scanning direction, the printing paper is exposed (printed) by a light beam carrying an image to form a latent image, and the latent image is developed by a processor. After processing, the image is visualized and an image on the film is reproduced to obtain a print.

By the way, in order to obtain a high-quality print in which a high-quality image is reproduced, it is essential that a film serving as an original image of the print is in a good condition. This film is transported in a camera, scanner, or the like for photographing, developing, reading (printing), and the like. At this time, the film surface comes into sliding contact with a support member or the like, and as a result, the film surface It may be scratched. Further, since the film is often handled in an ordinary environment in which air is not particularly cleaned, it is not rare that foreign matters such as dust and dirt adhere to the front and back surfaces.

As described above, the reading of a film image by a scanner is performed by irradiating the film with reading light to obtain projection light, and photoelectrically reading the projection light with a CCD sensor or the like. At this time, if a foreign substance adheres to the film surface or the film surface is damaged, the reading light (projection light) is blocked or diffused to reduce the light amount. As a result, the transmitted light amount of the reading light increases, and the light intensity of the projection light incident on the CCD sensor or the like is not appropriate for the image photographed on the film.

As a result, a high quality image can be obtained by reproducing foreign matter or a scratch in the obtained image as a shadow, or blurring the image around the scratch. I can no longer do it. For such issues,
Various countermeasures have been proposed. For example, registered patent No. 2
559970.

The above technique is directed to a method or an apparatus for correcting the effect of a film defect on an image stored in a storage medium (film), wherein the film is exposed to infrared energy and visible light energy, and the resulting defect is removed. The corresponding infrared energy distribution is detected in association with the position on the film, while the visible light energy distribution is detected in association with the position on the film, and for each position on the film, the detected infrared energy distribution intensity is detected. Is greater than a predetermined threshold, the visible light energy distribution intensity at the position is increased to a level that cancels out the infrared energy distribution intensity at the position, and if the detected infrared energy distribution intensity is equal to or less than the predetermined threshold, the visible light energy at the position is reduced. By correcting the light energy distribution intensity by interpolation, the film Is that to correct the influence of the defect.

[0011]

In a digital printer, a film scanner used for reading a film (hereinafter simply referred to as a scanner).
It is necessary to have a visible light sensor for detecting visible light as described above and a non-visible light sensor for detecting invisible light (normally, infrared light). As described above, since the refractive index differs depending on the wavelength of light, it has been considered in principle difficult to align the positions of these two types of sensors (generally, CCD sensors) due to chromatic aberration of magnification and axial chromatic aberration.

In addition, designing a lens with small chromatic aberration so that the visible light sensor and the invisible light sensor are aligned with each other has a problem that the lens becomes extremely expensive. . The lens here is
A lens for projecting a film original onto a CCD sensor. On the other hand, in the case of a lens whose chromatic aberration cannot be neglected, it is necessary to correct the positional deviation at the time of dust / scratch removal processing, and there is a problem that image processing becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and more specifically, without using invisible light, it is possible to use ordinary visible light on a film. Before and after the image reading, the visible light different from that for the image reading is used to detect not only the dust on the film but also dust / scratch present in the optical path of the film reading device, so that it is detected on the film and in the film reading device. It is an object of the present invention to provide a film reading method capable of preventing a dust or a scratch from being transferred to a print image and obtaining a high quality print image, and a film reading apparatus to which the method is applied.

[0014]

In order to achieve the above object, a film reading method according to the present invention comprises the steps of reading an image on a film using a first visible light sensor corresponding to the spectral sensitivity characteristic of the film. And a step of detecting dust or scratches on the film using a second visible light sensor that reads visible light different from the read wavelength range of the first visible light sensor.

In the film reading method according to the present invention, a sensor having a sensitivity in a valley between the absorption of the magenta color material and the absorption of the cyan color material of the color film is used as the second visible light sensor. And Also,
In the step of detecting dust or scratches, a threshold used for determination of dust or scratches is determined based on the film image information obtained by the first visible light sensor and the film dust obtained by the second visible light sensor. Alternatively, it is preferable to calculate based on the flaw image information.

The present invention can be embodied as a film reading apparatus to which the above method is applied.

That is, the present invention is embodied as a film reading apparatus having a first visible light sensor for reading an image and a second visible light sensor for reading dust or scratches. can do.

In the film reading apparatus according to the present invention, a sensor having a sensitivity in a valley between the absorption of the magenta color material and the absorption of the cyan color material of the color film is used as the second visible light sensor. Is preferred. Further, the threshold value for determining the dust or scratch used when reading the dust or scratch is obtained by using the image information of the film obtained by the first visible light sensor and the second visible light sensor. It is preferable to have a means for calculating based on the film dust or scratch image information.

[0019]

In the film reading method / apparatus according to the present invention, before and after the image is read on the film by the visible light, the visible light different from that for the image reading is used.
By detecting dust and scratches on the film, dust and scratches on the film are prevented from being transferred to the print image, and high quality print images can be obtained. Is played.

Specifically, for example, as a result of reading with visible light, if dust / scratch existing on the film is detected, the situation is notified to the operator and the instruction is given. By operating to perform image processing so that the scratches are not noticeable, the influence can be eliminated.

[0021]

Embodiments of the present invention will be described below in detail with reference to preferred embodiments shown in the accompanying drawings.

In the embodiment described below,
As a second visible light sensor for dust / scratch detection, a so-called “absorption” that appears between the absorption wavelength range of the magenta dye and the absorption wavelength range of the cyan dye of the color negative film as schematically shown in FIG. (Hereinafter referred to as "GR" light for the sake of convenience). A CCD sensor having a sensitivity maximum in the wavelength range (hereinafter, light corresponding to this wavelength range is referred to as "GR" light) (hereinafter, this sensor is referred to as "GR" sensor for convenience). Will be described.

In FIG. 3, curve A represents the total sum of the absorptions of the yellow, magenta, and cyan dyes of the negative film.
Curve C shows the dust / scratch absorption characteristics, respectively.
B, G, and R are CCD sensors (R, G, and B sensors) prepared corresponding to wavelength ranges near the absorption maximums of the yellow, magenta, and cyan dyes, respectively. GR is a CCD sensor (that is, the GR sensor) prepared corresponding to a wavelength range corresponding to a valley of absorption of each of the magenta and cyan dyes on the curve A.

FIG. 1 is a block diagram showing an outline of a photographic processing apparatus including a film reading apparatus (scanner) according to one embodiment of the present invention. Photo processing apparatus 10 shown in FIG.
A film scanner 11 that photoelectrically reads a film original, an image processing unit 12 that performs necessary image processing on an image read by the film scanner 11, and image data (exposure conditions) processed by the image processing unit 12 The image output apparatus 13 includes a printer 21 that scans and exposes photographic paper (photosensitive material) and a processor 22 that performs development processing on the exposed photographic paper. The image processing unit 12
Has a CRT monitor 12a and a keyboard 12b for verification.
Is connected.

FIG. 2 shows the above-described film scanner (hereinafter, referred to as a film scanner).
11 shows a detailed configuration example of a scanner 11. FIG.
Reference numeral 111 denotes a light source lamp, 112 denotes an aperture, 113 denotes a mirror box, 114 denotes a diffusion plate, 115 denotes a film to be read, 116 denotes an image pickup lens, 117 denotes a dichroic prism, 118 denotes an RGB 3-line CCD, and 119 denotes the aforementioned " FIG. 3 shows a one-line CCD for “GR” (where the absorption characteristics of each sensor are roughly as shown in FIG. 3). 120a is an amplifier, 120b is A
1 shows a / D (analog / digital) converter.

As shown in FIG. 2, an RGB three-line CCD
From 118, RGB image information is read and sent to the next stage (image processing unit 12) as digital data.
Also, from the “GR” one-line CCD 119, “G”
The dust / flaw information detected by the “R” light is sent to the next stage (image processing unit 12). Also, although not shown,
The scanner 11 generally includes detection means for reading the type of film to be processed (negative film / positive film, presence / absence of a magnetic layer, color / monochrome, etc.), or instruction means for instructing the type of film. Provided.

Hereinafter, the operation of the photographic processing apparatus 10 according to this embodiment will be described. When the film to be processed is set in the scanner 11, the scanner 11 first detects the type of the film. Here, it is assumed that the film is recognized as a 135 size (no magnetic layer, not APS), color negative film.

The scanner 11 performs the primary reading (pre-scan) of the film using RGB and "GR" light. The histogram of the obtained pre-scan image data RGB and “GR” is calculated, and the threshold value for dust / scratch determination is calculated.

The basics of the dust / scratch determination are as follows: (1) An image which becomes a “GR” image having a density value larger than the maximum density (hereinafter referred to as D _th1 ) of the “GR” image inherent to the film. Is judged as dust / scratch. (2) A density point obtained by adding a predetermined value th2 from, for example, the 99% point of the “GR” image histogram (D in FIG. 4)
An image having a density value _{exceeding the} point indicated by _th2 ) is _{regarded as dusty} even if the density is lower than the above-mentioned _Dth1.
Judge as a scratch. That is.

When a sensor for invisible light such as infrared light is used as the dust / scratch sensor, only the determination in the above (1) was sufficient, but the "GR" sensor used here was not sufficient. In the wavelength range of sensitivity, the influence of cyan and magenta dyes is not sufficient, so that the determination in the above (1) is not sufficient (that is, the determination of dust / scratch is omitted).
Other criteria such as are required.

However, in some _overexposed films, the above D _th2 may be high. In such a case, the judgment of (2) above has no effect on the omission of judgment.

After the prescan, the two threshold values D _th1 and D _th1
After calculating _th2 and making a determination, the scanner 11
A fine scan of B and “GR” is performed. Here, if the threshold value D _th3 is set for each fine scan pixel by the following method, it is effective against omission of dust / scratch determination.

That is, a new threshold value D _th3 = f (D _R , D _G ) is created for each pixel using a value such as a function approximation of the _R density (D _R ) and the G density (D _G ). Then, if polynomial approximation, fine scan D _GR (density of GR) becomes D
If it is larger than _th3, it can be determined that the object is dust / scratch.

That is, in the processing for determining the presence / absence of dust / scratch according to the present embodiment, the determination of the first step based on D _th1 , 9
The determination of the second step based on the 9% point and the determination of the third step based on D _th3 are sequentially performed, so that the presence / absence of dust / scratch can be determined without missing (missing determination). is there.

The threshold _values D _th1 , D _th2 , and D _th3 are as follows.
All may be used for determination, or may be selected and used from among three according to the situation.

The above embodiment is merely an example of the present invention, and it goes without saying that the present invention is not limited to this. For example, the film to be read may be of any type such as a negative film / positive film and a magnetic layer.

In consideration of this point when designing a film, if a clear blank area (zone) is formed in the absorption wavelength range of the dye of the film without deteriorating the color reproduction performance, the present invention can be realized. In the film reading method according to the above, it is possible to greatly improve the accuracy of determining the presence / absence of dust / scratch.

[0038]

As described above in detail, according to the present invention, an image on a film is read by a visible light sensor, and visible light that does not overlap with the read wavelength range of the above visible light sensor is read. Using the second visible light sensor,
A film reading method for detecting dust and scratches on a film to prevent dust and scratches on the film from being transferred to a print image and obtaining a high quality print image, and a method for reading the film. Can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an outline of a photo processing apparatus including a scanner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a film scanner 11 in the photographic processing apparatus shown in FIG.

FIG. 3 is a diagram showing an example of an absorption curve of a dye of a negative film.

FIG. 4 is an explanatory diagram of determination of dust / flaw detection.

[Explanation of symbols]

 Reference Signs List 10 photo processing device 11 film scanner 111 light source lamp 112 aperture 113 mirror box 114 diffusion plate 115 film to be read 116 imaging lens 117 dichroic prism 118 RGB 3-line CCD 119 1-line CCD for "GR" light 120a amplifier 120b A / D converter 12 image processing unit 13 image output device

Claims (6)

[Claims] A step of reading an image on the film using a first visible light sensor corresponding to a spectral sensitivity characteristic of the film; and a step of transmitting visible light different from a reading wavelength range of the first visible light sensor. Detecting dust or scratches on the film using a second visible light sensor for reading. 2. The film reading method according to claim 1, wherein a sensor having a sensitivity in a valley between absorption of a magenta color material and absorption of a cyan color material of the color film is used as the second visible light sensor. 3. The method according to claim 1, wherein the step of detecting the dust or the scratch includes setting a threshold value used for determining the dust or the scratch on the film image information obtained by the first visible light sensor and the second visible light sensor. 3. The film reading method according to claim 1, wherein the calculation is performed based on obtained dust or scratch image information of the film. 4. A film reading apparatus comprising: a first visible light sensor for reading an image; and a second visible light sensor for reading dust or scratches. 5. The film reading apparatus according to claim 4, wherein a sensor having a sensitivity between a valley between a magenta color material absorption and a cyan color material absorption of the color film is used as the second visible light sensor. 6. A method according to claim 6, wherein a threshold value for judging dust or scratches used for reading said dust or scratches is determined by using image information of a film obtained by said first visible light sensor and said second visible light. The film reading device according to claim 4 or 5, further comprising: means for calculating based on dust or flaw image information of the film obtained by the sensor.