JPH06217091A - Picture reading method - Google Patents

Abstract

PURPOSE:To enable accurate picture reading by setting the reading density range from the picture density at the middle area of a picture in the case that the difference between the maximum picture density and the minimum picture density exceeds the measurable range. CONSTITUTION:The picture is divided into, for example, 25 by 5X5, restricting areas up to S1-S25. Then the maximum picture density and the minimum picture density in respective areas are detected. Then, the maximum picture density and the minimum picture density with entire picture areas as an object are detected. When the difference between the maximum picture density and the minimum picture density is within the prescribed density range of this scan section, the minimum picture density is defined as the reading density range in this scan from the detected maximum picture density. On the other hand, when the difference exceeds the measuring density range of this scan section, the reading density range is set by the picture density at the middle area of the picture. Thus, the reading density range in the main scan is set by the picture density data from the areas up to S1-S9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading method for reading a transparent original such as a negative film or a reversal film, or an original image such as a printed matter or a photograph. More specifically, the present invention relates to an image reading method capable of performing highly accurate image reading in which a high-quality reproduced image can be obtained by appropriately setting a measurement density range of image reading.

[0002]

2. Description of the Related Art Recently, image information recorded on a photographic film (hereinafter referred to as a film) such as a negative film and a reversal film is photoelectrically read, and the read image is converted into a digital signal, and then various image processing is performed. The development of a digital photo printer has been progressing in which printing is performed by subjecting a photosensitive material such as photographic paper to scanning exposure with recording light modulated according to this image information.

A digital photo printer is a print image editing layout such as editing a combination of a plurality of images and dividing an image, editing characters and images, color / density adjustment, scaling ratio, and the like.
Various image processing such as contour enhancement can be performed freely,
It is possible to output a finished print that has been edited and image-processed freely according to the purpose. Also, in conventional printing by surface exposure, it is not possible to reproduce all the image density information recorded on a film or the like in terms of density resolution, spatial resolution, color / density reproducibility, etc. For example, it is possible to output a print that reproduces almost 100% of the image density information recorded on the film.

Such a digital photo printer is basically a reading device for reading an image recorded on a document such as a film, a set-up device for image-processing the read image to determine subsequent exposure conditions, and the determined device. The image forming apparatus is configured to scan and expose a light-sensitive material according to the above exposure conditions to perform development processing.

In an apparatus for reading an image recorded on a film or the like, when reading by slit scanning, for example,
The film is irradiated with slit-shaped reading light extending in the dimensional direction, and the film is moved in a direction substantially orthogonal to the one-dimensional direction (or the reading light and the photoelectric conversion element are moved).
By doing so, the film is two-dimensionally scanned by the reading light. The transmitted light carrying the film image transmitted through the film is imaged on the light receiving surface of a photoelectric conversion element such as a CCD line sensor, photoelectrically converted and read. The read light amount data is amplified, converted into a digital signal by A / D conversion, subjected to various image processing such as correction of characteristic variations by each CCD element, density conversion, and magnification conversion, and transferred to a setup device. To be done.

In the setup device, the transferred image information is reproduced as a visible image on a display such as a CRT. The operator looks at the reproduced image and, if necessary, further corrects gradation correction, color / density correction, etc., on this reproduced image (setting of setup conditions), and the reproduced image passes as a finished print (verification OK). If there is, it is transferred to the image forming apparatus as image information for recording.

In the image forming apparatus, if the image recording by raster scanning (light beam scanning) is used, exposure of the three primary color photosensitive layers formed on the photosensitive material, for example, three colors of R, G and B is performed. Are modulated in accordance with the image information for recording to be deflected in the main scanning direction (corresponding to the one-dimensional direction), and the light beams are exposed in a direction substantially orthogonal to the main scanning direction. By sub-scan transporting the material (relatively sub-scanning the deflected light beam and the photosensitive material), the photosensitive material is two-dimensionally scanned and exposed by the light beam modulated according to the recorded image, The image of the read film is recorded on the light-sensitive material.

The exposed light-sensitive material is then developed according to the type of light-sensitive material. For example, in the case of a silver salt photographic light-sensitive material, development processing such as coloring / development → bleaching / fixing → washing → drying is performed to obtain a finished product. It is output as a print.

[0009]

As is well known, a film is not always exposed with an appropriate amount of light, and various exposures such as underexposure (so-called underexposure) and overexposure (so-called overexposure) are performed. Image density D that can be recorded (recordable) on normal negative film
The maximum density of (= logE) reaches about 2.8 to 3.2, and the maximum density of an image recorded on a normal reversal film reaches about 3.2 to 3.8.

Here, in order to obtain a high quality finished print with a digital photo printer, it is necessary to use a photoelectric conversion element having a high spatial resolution and a high density (light quantity) resolution. For example, a CCD sensor or the like is favorably used. It However, in general, a photoelectric conversion element having excellent spatial resolution and density resolution has a narrow measurable density range (dynamic range), and it is difficult to measure the entire density range of the negative or reversal film as described above. .

Therefore, in an image reading apparatus used in a digital photo printer or the like, in order to set a reading density range by the photoelectric conversion element, the measured density of the photoelectric conversion element is measured before the image reading of the film for printing. Pre-reading (pre-scanning) is performed to roughly read the image on the film with the area widened, and the density range of image reading in image reading (main scanning) for output to the finished print is set. In this scan,
According to the set reading density range of the image, the reading density range is adjusted (reduced) by giving an offset to the photoelectric conversion element, and for example, the light amount adjustment of the reading light source or the gain of the amplifier is changed, or the photoelectric conversion element is changed. In the case of CCD, the offset is given by changing the storage time.

However, depending on the shooting conditions of the film, the density range of image reading specified by the prescan may exceed the density range that can be read by the main scan. In such a case, image reading is performed within the range that can be read in the main scan with the maximum image density or the minimum image density obtained by the prescan as a reference. That is, when the maximum image density obtained in the prescan is used as a reference, the image information in the vicinity of the minimum image density cannot be read in the main scan,
On the contrary, when the minimum image density is used as a reference, the image information near the maximum image density cannot be read.

However, in this image reading method, there are many cases in which necessary image information cannot be read when, for example, stroboscopic photography or a person shaded by trees is photographed in the suburbs, an image reproduced and output, that is, a finished image. This is a major factor in the deterioration of print image quality.

An object of the present invention is to solve the above-mentioned problems of the prior art, and is when the density range of image reading set by the prescan exceeds the density range that can be read by the main scan. Even if the read image density range is appropriately set, it is possible to perform high-precision image reading by reading all necessary image information, and to provide an image reading method capable of stably obtaining a high-quality output image. Especially.

[0015]

In order to achieve the above-mentioned object, the present invention reads the image carried on the original by reading the reflected light of the original or the transmitted light of the original by a photoelectric conversion element, Pre-reading is performed by roughly reading the image carried on the original document by a photoelectric conversion element having a wide measurement density range, and the difference between the maximum image density and the minimum image density of the image density obtained by the pre-reading is the photoelectric conversion element in the main reading. If within the measured density range of, the maximum image density in the pre-reading to the minimum image density is set to the read density range in the main reading, the difference between the maximum image density and the minimum image density obtained by the pre-reading, When the measured density range of the photoelectric conversion element in the main reading is exceeded, the reading in the main reading starts from the image density in the central area of the image. To provide an image reading method characterized by setting the degree range.

Further, in the image reading method, it is preferable that a region of 30 to 60% of the entire image from the center of the image is the central region of the image.

In the image reading method, it is preferable that, in the central region of the image, image density data closer to the center of the image is weighted with a higher weight to set the measured density range in the main reading.

[0018]

INDUSTRIAL APPLICABILITY The present invention roughly reads an image carried on an original such as a negative or positive film or a printed matter by a photoelectric conversion element having a wide measurable density range (hereinafter referred to as a measured density range). Look-ahead (pre-scan)
Then, the density range for image reading (hereinafter referred to as the reading density range) is set according to the image density information obtained by the prescan, and the image carried on the document is read in detail (main scanning) The present invention relates to an image reading method for performing.

Conventionally, in the image reading in which the prescan is performed to set the read density range and the main scan is performed, the read density range in the main scan set by the prescan is used for the main scan. When the measured density range of the photoelectric conversion element is exceeded, the image is read within the range that can be read by the main scan with the maximum image density or the minimum image density obtained by the prescan as a reference. In this method, the image information near the maximum or minimum image density cannot be read depending on whether the maximum image density or the minimum image density is selected as a reference. As described above, a high quality output image cannot be obtained.

On the other hand, in the image reading method of the present invention, when the difference between the maximum image density and the minimum image density read by the prescan is within the measured density range in the main scan, this maximum image density If the difference between the maximum image density and the minimum image density read by the pre-scan exceeds the measurable range in the main scan, the range from the density to the minimum image density is set as the read density range, and From the image density, the reading density range in the actual reading is set.

In shooting with a normal camera, exposure control is performed by average photometry or center-weighted photometry. Here, even if it is called average photometry, it is rare to measure the entire surface of the screen shot on the film and average it out. Usually, the average amount of light is calculated from the data of 30 to 60% of the central area of the entire screen, Exposure control is performed. Further, in photographing using a compact camera or a zoom lens, the peripheral light amount is apt to be insufficient, and the central density and the peripheral density are largely deviated, and the density range of an image to be recorded is unnecessarily widened due to the insufficient peripheral light amount. In some cases, and when photographing is performed using a strobe at night, the peripheral portion is in a strong under state, and the density range of the image is unnecessarily widened.

That is, in the case of an image recorded on a film which is normally taken, most of effective image information is effective even when the density range of the recorded image is wide (especially when the image density range is unduly wide). It is carried in the central region.
Therefore, according to the image reading method of the present invention having the above configuration, a high-quality output image is obtained even when the image density range recorded on the document exceeds the measured density range in the main scan. Therefore, it is possible to realize highly accurate image reading by surely reading the image information required.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The image reading method of the present invention will be described in detail below with reference to the preferred embodiments shown in the accompanying drawings. FIG. 1 conceptually shows an example of a digital photo printer that implements the image reading method of the present invention. In FIG. 1, the flow of image information is shown by a solid line, the flow of control signals is shown by a broken line, and light is shown by a dashed line.

Digital photo printer 1 shown in FIG.
0 is a full-color print image (output image) after reading the transmission image recorded on the developed negative film or reversal film of 24 sheets, 36 sheets, etc. one frame at a time and performing the necessary image processing. The image is recorded on the photosensitive material A by scanning exposure, and the finished print P is output by developing the image. Basically, the image is recorded on the exposed (roll) film F. An image reading apparatus 12 for carrying out the image reading method of the present invention for sequentially reading and processing a transparent image (hereinafter referred to as an image) and a simulation image of the read image are displayed, and a quality test is performed to form an image. The setup device 14 that determines the conditions (setup conditions), and the photosensitive material A is scanned and exposed according to the image forming conditions determined by the setup device 14. And, more configured image forming apparatus 16, finished prints P the exposed photosensitive material A was developed.

In FIG. 1, an image reading device 12 carries out the image reading method of the present invention. Basically, a pre-scan (pre-read) unit 18 and a main-scan (main-read) unit 2 are provided.
0, a prescan calculation storage unit 22, a read control unit 24, an input timing control unit 26, an amplifier 28, an A / D converter 30, a CCD correction unit 32, a density conversion unit 34, and a magnification conversion unit 36. Such an image reading device 12 photoelectrically reads the image recorded on the film F frame by frame while conveying the developed (roll) film F in the direction of the arrow a in the drawing, and reads the read image information. A / D
Various types of image processing such as conversion, correction of measured values, density conversion, magnification conversion, sharpness, etc. are performed, and this image information is sent to the setup device 14.

The illustrated image reading apparatus 12 according to the present invention
The pre-scan unit 18 and the main-scan unit 20 are provided independently of each other. First, the image recorded on the film F is roughly read by the pre-scan unit 18 to obtain an outline of the image. After the reading conditions such as the reading density range for image reading are set according to the result of the prescan, the image of the film F is read in the main scanning unit 20 with high spatial resolution and density resolution.

The prescan section 18 has a prescan light source 38, an imaging lens 44, and a prescan line CCD 46 (hereinafter referred to as the prescan CCD 46), and further, the film F at a predetermined speed. It has a pair of conveying rollers (not shown) for conveying.

The light source 38 emits pre-reading light for pre-scanning the image of the film F, and if it can emit a sufficient amount of light for reading by the pre-scan CCD 46, it is usually a halogen lamp or a fluorescent lamp. Any of various light sources used for reading the image can be used.

The film F is held at a place other than the image region and is conveyed at a predetermined conveyance speed in the scanning conveyance direction indicated by the arrow a, and the entire surface is irradiated with the pre-read light from the light source 38.

The transmitted light transmitted through (the image recorded on) the film F is pre-scanned CC by the imaging lens 44.
An image is formed at D46. The pre-scan CCD 46 is, for example, R (red), G (green) and B (blue).
It is composed of three CCD line sensors corresponding to each of the three primary colors of R, G and B, and the amount of transmitted light is decomposed into the three primary colors of R, G and B, measured, and photoelectrically converted to R, G and B.
Read as each image information of.

Here, in the image reading apparatus 12 of the illustrated example, the prescan performed by the prescan unit 18 is mainly to set the image reading density range in the main scan (hereinafter referred to as the reading density range) and to perform the filter unit. It is performed for the control of 52. Therefore, the prescan CCD 46
The measurement of the transmitted light according to (2) does not need to have high spatial resolution and density resolution as long as it has a measurement density area (dynamic range) capable of measuring the entire density range recorded on the film F.

The light amount data (image information) read by the prescan unit 18 is stored in the prescan calculation storage unit 2
2 is transferred. The prescan calculation storage unit 22 calculates the transferred image information into image density information of the image, and sets the read density range in the main scan, the insertion amount of each filter in the filter unit 52 of the main scan unit 20, and the like. .

Here, since the image reading device 12 of the illustrated example implements the image reading method of the present invention, the difference between the maximum image density and the minimum image density of the image density information read by the prescan CCD 46 is different. If it is within the density range measured by the main scan unit 20 (line scan CCD 64 for main scan), the maximum image density to the minimum image density is set as the read density range in the main scan, and the maximum image density and the minimum image density in the prescan are set. If the difference in density exceeds the density range measured by the main scan unit 20, the read density range in the main scan is set based on the image density of the central area of the image. As a method of setting the reading density range, various methods such as a method of creating a density histogram and setting the reading density range from this can be used, and the following method is exemplified as a suitable example. .

In this method, the image is divided into a plurality of parts as shown in FIG.
The area is divided into five areas S1 to S25, and the maximum image density and the minimum image density in each area are detected. The number of divisions of the image is not particularly limited, but as will be described later, when the reading density range is set from the central area, this area is preferably 30 to 60%, so 5 × 5 = 25.
˜9 × 9 = 81 is preferable. Of course, the number of divisions in the vertical direction may be different from that in the horizontal direction.

Next, the maximum image density and the minimum image density for the entire image area are detected. If the difference between the maximum image density and the minimum image density is not within the measured density range of the main scan unit 20, the maximum image density detected here to the minimum image density is set as the read density range in the main scan. On the other hand, when the difference between the detected maximum image density and the minimum image density exceeds the measured density range of the main scanning unit 20, the read density range is set from the image density of the central area of the image, and in the illustrated example. Sets the read density range in the main scan from the image density data of the areas S1 to S9.

According to the study by the present inventor, as described above,
With a normal camera, the exposure control is 30 to 30 in the central area of the entire screen.
It is performed by calculating the average amount of light from the data of 60%.
When shooting with a compact camera or using a sumo lens or strobe, the peripheral area's exposure amount becomes lower than the central area's exposure amount. In many cases, the obtained image density range becomes unreasonably wide. That is, in a normal film, when the recorded image density range is unreasonably wide, important (necessary for outputting the high-quality finished print P) image information is carried in almost the central area of the image, In many cases, the image information of the peripheral portion carries image density information that is unnecessary (and may cause deterioration of the image quality of the finished print P). In addition, a film shot by a person skilled in the art such as a professional photographer may carry important image information in the peripheral portion of the image, but the image recorded on such a film has a density range Is rarely unreasonably wide, and in most cases, the recorded image density range falls within the measured density range in the main scan.

Therefore, when the difference between the maximum image density and the minimum image density of the image density information read by the prescan is within the measured density range in the main scan, the maximum image density to the minimum image density are read. When the density difference is set as the density range and the density difference exceeds the measurement density range of the main scan, the image reading method of the present invention sets the reading density range in the main scan to be higher than the image density of the central region of the image. It can be reliably read without missing the image density information necessary to output a finished print with high image quality, and can be read from film (original) film shot under various conditions such as flash photography and photography using a zoom lens. Thus, a high-quality finished print (output image) can be stably formed.

The method of setting the central region is not particularly limited, but it is preferable to set the central region so as to occupy an area of 30 to 60% of the entire image from the center of the image. According to the study by the present inventor, when the image density range recorded on the film is wide, by setting the central region to this range, the necessary image information can be almost certainly detected by the main scan. Thus, it is possible to stably form a high quality finished print.

The method of determining the read density range from the image density data of the central area is not particularly limited, and the method of setting the read density range from the maximum image density to the minimum image density of the set central area is the central area. Various methods such as a method of obtaining the maximum image density and the minimum image density of S1 to S9 and setting the average thereof as the reading density range can be used, but it is preferable to weight the area closer to the center of the image. It is preferable that the reading density range is set by carrying out.

In this method, in the central region from S1 to S9, for example, the region S1 which is the center of the image is weighted four times, and the region S2 which is adjacent to the region S1 which is in the vicinity of the central region S1. The weighted average of S1 to S9 is obtained by multiplying S5 by a double weight and leaving the remaining areas S6 to S9 as they are (the weight of a single time) as measured data, and the read density range in the main scan is obtained from this data. Set.

In the prescan calculation storage unit 22,
In addition to setting the image reading density range in the main scan, the image exposure state is determined from the image density information obtained by the prescan (appropriate exposure, underexposure or overexposure), Main scanning unit 2
The insertion amount of each filter in the 0 filter unit 52 is set.

The read density range and the read timing in the prescan set in the prescan calculation storage unit 22 are transferred to the main scan control unit 26, and the filter insertion amount is transferred to the dimming control unit 24. The main scan control unit 26 receives a signal from the pre-scan calculation storage unit 22 to control the read density range by the main scan line CCD 64, the main scan line CCD 64, the A / D converter 30, the CCD correction unit 32, and the like. Further, the timing selector 88 of the setup device 14 controls the processing timing of image information. On the other hand, the dimming control unit 24
Receives a signal from the pre-scan calculation storage unit 22 and adjusts the insertion amount of each filter in the filter unit 52 of the main scan unit 20. In the illustrated example, the read density range is adjusted by adjusting the filter insertion amount in the filter unit 52, adjusting the accumulation time of the main scan line CCD 64 (adjusting the read timing), and the like.

The main scanning unit 20 is for reading an image for output (recording on the finished print P), and has a high spatial resolution (for example, for an image for which pre-scan has been completed, depending on the result of the pre-scan. If it is a 35 mm film, it is read photoelectrically with a density resolution of 1100 pixels × 1700 lines) and transferred to the amplifier 28 as output image information. The main scan unit 20 as described above basically includes a light source 50 for main scan and a filter unit 52.
, The condensing unit 54, the pair of transport rollers 56, and the imaging lens 6
2 and a main scan line CCD 64 (hereinafter referred to as a main scan CCD 64).

The light source 50 emits reading light for reading the image of the film F, and the main scan CCD 64
Any of various light sources used for ordinary image reading such as a halogen lamp and a fluorescent lamp can be used as long as the light is emitted with a sufficient amount of light for reading.

The reading light emitted from the light source 50 then enters the filter section 52. The filter unit 52 cuts unnecessary components such as heat and ultraviolet rays from the reading light, and
The light amount and color tone of the reading light are adjusted according to the exposure state of the image to be read, and a filter 52N in which a heat insulating filter, an ultraviolet absorbing filter, and the like are combined, and a color filter of three primary colors, for example, a cyan filter 52C, a magenta filter 5
2M, and three color filters of the yellow filter 52Y. The amount of insertion of the reading light of each filter into the optical path is controlled by the dimming control unit 24 described above.

The reading light that has passed through the filter section 52 enters the condenser section 54. The condensing unit 54 diffuses and condenses the incident reading light inside, and emits the reading light as slit-like reading light having a longitudinal direction in a direction substantially orthogonal to the scanning direction (direction of arrow a in the drawing) from the opening 54a. And makes it enter the film F. Needless to say, the slit-shaped reading light emitted from the light collecting unit 54 needs to be longer in the longitudinal direction than in the width direction of the film F.

The conveying roller pair 56 holds the film F at a place other than the image area, and in accordance with a predetermined conveying speed in the scanning conveying direction indicated by the arrow a, for example, a clock rate (accumulation time) of the main scan CCD 64. For example, if the film F is a 35 mm film, it is conveyed at a predetermined conveying speed for reading 1700 lines, and a drive source such as a motor (not shown) is engaged. Here, as described above, the reading light has a slit shape having a longitudinal direction in a direction substantially orthogonal to the scanning direction, so that the film F (image) conveyed in the scanning direction consequently covers the entire surface by the reading light. Two-dimensional slit scanning is performed.

Although not shown in order to simplify the drawing, the image reading device 12 is not limited to the conveying roller pair 56.
Needless to say, various members for realizing stable scanning and transport of the film F, such as a pair of rollers and a guide member that move in synchronization with the transport roller pair 56, are provided. Further, the scanning / conveying device for the film F has a pair of conveying rollers
In addition to the method described in No. 6, as long as the reading light can pass through the film F, such as a belt transportation and a sprocket gear transportation, various known methods for transporting a long object can be used.

The slit-shaped transmitted light that has passed through the film F is imaged on the light receiving surface of the main scan CCD 64 by the imaging lens 62, and the amount of light is measured. Main scan CCD
64 is three CCs corresponding to the three primary colors of R, G and B.
A D line sensor is used, and the transmitted light that carries the recorded image that has passed through the film F is split into, for example, the three primary colors R, G, and B, and the respective light quantities are photoelectrically converted and measured. , The reading density range (light amount range) of the image recorded on the film F set as described above
Read with.

In the illustrated example, in the case of a 35 mm film, for example, one line (that is, the longitudinal direction of slit-like transmitted light) is read by 1100 pixels. Therefore, in the image reading apparatus 12 of the illustrated example, if the image is recorded on a 35 mm film, 1100 pixels × 17
Read with a high spatial resolution of 00 lines. Further, the main scan CCD 64 needs to have higher density resolution than the pre-scan CCD 46, but in order to obtain a high quality finished print, the density D (= logE) is 0.01.
It is preferable to secure a degree of resolution.

Further, the reading density range by the main scan CCD 64 is set as described above, and high-precision image reading is performed by surely reading the image density information necessary to obtain the finished print P with high image quality. Be seen.

In the image reading apparatus 12 of the illustrated example, the line CCD is used as the photoelectric conversion element in both the prescan section 18 and the main scan section 20, but the present invention is not limited to this, and an area CCD is used. Good. Also,
Besides the CCD, various known photoelectric conversion elements such as a photomultiplier can also be used.

Further, in the main scanning unit 20 of the illustrated example, the prescan unit 18 reads the image recorded on the film F by slit scanning, but the present invention is not limited to this, and the flying Of course, a spot scanner (FSS), a light beam scan (so-called raster scan), or the like may be used.

The R, G and B image information (hereinafter referred to as image information) of the image on the film F read by the main scan CCD 64 is amplified by the amplifier 28 and converted into a digital signal by the A / D converter 30. To be done. The image information is then subjected to an error (variation) in each pixel of the main scan CCD 64 by the CCD correction unit 32.
After correcting variations in dark current and dark attenuation, the magnification conversion unit 36 performs magnification conversion and sharpness enhancement (unsharp mask), and then the setup device 1
4 is transferred.

The setup device 14 is the image reading device 1.
The quality of the image information transferred from 2 is verified, color / gradation correction is performed if necessary, and transferred to the image forming apparatus 16 as image information for output (printing). In addition, a first selector 70, three frame memories (FM) 72a, 72b and 72c, a second selector 74, a setup calculation storage unit 76, and a color gradation correction display control unit 78 (hereinafter referred to as a display control unit 78). And)
Display 80, input means 82, and color correction unit 84
A tone correction unit 86, a timing selector 88, and an output timing control unit 90.

The image information from the magnification conversion section 36 is first transferred to the first selector 70. The first selector 70 outputs the image information of each frame of the film F to the three frame memories 7
2a, 72b and 72c are sequentially allocated. That is,
For example, the first selector 70 initially connects the transfer path so as to store the image information of the first frame in the frame memory 72a. When the storage in the frame memory 72a is completed, the first
The selector 70 switches the transfer path so that the image information of the second frame is stored in the frame memory 72b.

On the other hand, when the image information of the first frame is stored in the frame memory 72a, the second selector 74 connects the frame memory 72a, the setup calculation storage section 76 and the display control section 78. The setup calculation storage unit 76 calculates optimum image processing conditions (setup conditions) for this image according to the prescan image information transferred from the prescan calculation storage unit 22 and the image information read from the frame memory 72a. Then, the display control unit 78 is controlled based on this result. The display control unit 78 displays a simulation image corresponding to the finished print under this condition on the display 80 based on the image information read from the frame memory 72a and the instruction signal from the setup calculation storage unit 76.

The operator checks the quality of the image displayed on the display 80 to check the quality. If the test is passed, the start key of the input means 82 is pressed. The tone correction key is used to input an instruction for color and / or tone correction to the input means 82. The setup calculation storage unit 76 controls the display control unit 78 according to the input instruction for color and / or gradation correction, and the display control unit 78 displays the simulation image again on the display 80 according to this control. This operation is repeated until the quality inspection of the image displayed on the display 80 passes.

As a result of the above operation, when the quality test is passed and the start key of the input means 82 is pressed, the setup calculation storage unit 76 performs color correction of the color correction and gradation correction signals according to the set-up conditions that have been established. The data is transferred to the unit 84 and the gradation correction unit 86. At the same time, the second selector 74 connects the frame memory 72a and the color correction unit 84, and the image information read from the frame memory 72a is processed by the color correction unit 84 and the gradation correction unit 86 so that the color / color according to the setup condition is satisfied. Gradation correction is performed and the image is transferred to the image forming apparatus 16. Further, the second selector 74 simultaneously includes the frame memory 72b, the setup calculation storage unit 76, and the display control unit 78.
Are connected to each other, and the quality of the image stored in the frame memory 72b is similarly verified.

The output timing control section 90 outputs from the setup calculation storage section 76, the display control section 78, the color correction section 84, the gradation correction section 86, and the like of the setup apparatus 14, and further outputs to the image forming apparatus 16. Outputs from the respective parts such as the D / A converter 92, the AOM driver 94, etc. provided and the driving of the polygon mirror 96 are controlled by the output timing control section 90.

The setup device 14 in the illustrated example has three frame memories 72a, 72b and 72c, but the number of frame memories is not limited to three, and one, two, or four or more frames can be used. It may have a memory. Since the digital photo printer 10 of the illustrated example is basically composed of three devices, that is, the image reading device 12, the setup device 14, and the image forming device 16, the processing efficiency and the cost of the digital photo printer 10 are reduced. Considering this, it is considered that the number of frame memories is most balanced among the three in the illustrated example.

The image forming apparatus 16 is the setup apparatus 1
4, the photosensitive material A is scanned and exposed by light beam scanning in accordance with the image information transferred from 4, and the exposed photosensitive material A is developed and output as a finish print P. It has a converter 92, an AOM driver 94, an image exposure section 98, and a developing section 100.

The image information output from the setup device 14 is converted into analog image information by the D / A converter 92 and then transferred to the AOM driver 94.
The AOM driver 94 drives the acousto-optic modulator (AOM) 104 of the image exposure unit 98 so as to modulate the light beam according to the transferred image information.

On the other hand, the image exposure section 98 scans and exposes the photosensitive material A by light beam scanning (raster scan) to record the image of the image information on the photosensitive material A, which is conceptually shown in FIG. As described above, a light source 102R that emits a light beam in a narrow band wavelength region corresponding to the exposure of the R photosensitive layer formed on the photosensitive material A, a light source 102G that similarly corresponds to the exposure of the G photosensitive layer, and a B photosensitive layer. Light source of the light beam of the light source 102B corresponding to the exposure of A, and the light beam emitted from each light source are respectively modulated according to the recorded image A
It has OMs 104R, 104G and 104B, a polygon mirror 96 as an optical deflector, an fθ lens 106, and a sub-scanning conveying means 108 for the photosensitive material A.

Light source 102 (102R, 102G, 102)
Each of the light beams emitted from B) and traveling at different angles is associated with the corresponding AOM 104 (104).
R, 104G, 104B). The light source 10
Various light beam light sources capable of emitting a light beam of a predetermined wavelength corresponding to the photosensitive layer of the photosensitive material A can be used as 2, and various semiconductor lasers, LEDs, gas lasers such as He-Ne lasers, and the like can be used. It is illustrated. Further, it may be a multiplexing optical system that multiplexes the respective light beams. To each AOM 104, R, G, and B drive signals r, g, and b corresponding to the recorded image are transferred from the AOM driver 94, and the incident light beam is intensity-modulated according to the recorded image.

Each of the light beams modulated by the AOM 104 is incident on and reflected at substantially the same point of a polygon mirror 96 as an optical deflector, is deflected in the main scanning direction (the arrow x direction in the drawing), and then the fθ lens 104. Is adjusted to form a predetermined beam shape at a predetermined scanning position z by
It is incident on the photosensitive material A. The optical deflector may be not only the polygon mirror shown in the drawing but also a resonant scanner, a galvanometer mirror, or the like. In addition, it goes without saying that such an image exposure section 98 may be provided with a light beam shaping means and a surface tilt correction optical system, if necessary.

On the other hand, the photosensitive material A is loaded in a predetermined position while being wound in a roll and shielded from light. Such a photosensitive material A is drawn out by a drawing-out means such as a drawing-out roller and cut into a predetermined length by a cutter (not shown), and then a pair of rollers 108a arranged across a scanning position z constituting the sub-scanning means 108. And 108b
While being held at the scanning position z, it is sub-scanned and conveyed in a sub-scanning direction (direction of arrow y in the figure) substantially orthogonal to the main scanning direction. Here, since the light beam is deflected in the main scanning direction as described above, the entire surface of the photosensitive material A conveyed in the sub scanning direction is two-dimensionally scanned by the light beam, and the photosensitive material A is set on the setup device 14. The image of the transferred image information is recorded.

The exposed photosensitive material A is then carried into the developing section 100 by the conveying roller pair 110 and subjected to a developing process to be a finished print R. Here, for example, when the photosensitive material A is a silver salt photographic photosensitive material, the developing unit 10
Reference numeral 0 is composed of a color developing / developing tank 112, a bleaching / fixing tank 114, washing tanks 116a, 116b and 116c, a drying section 118, etc. The photosensitive material A is subjected to a predetermined processing in each processing tank to obtain a finished print R. Is output.

The digital photo printer 10 described above
The operation timing of the above is conceptually shown in FIG.

In the illustrated example, the light beam is directed to the AOM10.
However, in addition to this, the light beam may be modulated according to the recorded image if the light source such as an LD is capable of direct modulation. In addition to the two pairs of rollers arranged with the scanning position sandwiched therebetween, the sub-scanning conveying means includes an exposure drum for holding the photosensitive material at the scanning position and two nip rollers arranged with the scanning position sandwiched therebetween. Good.

Further, in addition to the scanning of the light beam in the illustrated example,
It may be a so-called drum scanner in which a photosensitive material is wound around a drum, a light beam is incident on one point, and the drum is rotated and moved in the axial direction. In addition to the light beam scanning, surface exposure using a surface light source and a liquid crystal shutter may be used, or exposure using a linear light source such as an LED array may be used. It is also possible to output an image to a display such as.

[0072]

EXPERIMENTAL EXAMPLES The present invention will be described in more detail with reference to specific experimental examples of the image reading method of the present invention.

Digital photo printer 1 shown in FIG.
0, the prescan unit 12 (prescan CCD
46), 35 mm negative film to 400 dpi
With resolution (reading size 63.5 μm) of 512 ×
It was read at 341 pixels (about 32.5 x 21.6 mm on the film). The original 35 mm negative film was taken by strobe photography, and had a wide image density range in which the central portion was bright and the peripheral portion was dark on average. In addition, a part of the image has a scratch.

As shown in FIG. 2, the read image of the 35 mm negative film is divided into 25 by 5 × 5 (102 × 38 pixels per area, the extra portion is cut off), and each area is maximized. The image density and the minimum image density were detected. As a result, when the magenta density is taken as a representative example, the difference between the maximum image density and the minimum image density of the entire image (image density range) is 2.15, the image density range of the central regions S1 to S9 of the image is 1.42, Further, the region S1 at the center of the image is weighted four times, the regions S2 to S5 adjacent to S1 are weighted twice, and the other regions S6 to S9 are weighted one time. The image density range of the central region was 1.18.

Based on the various image density ranges obtained by the prescan, the reading density range by the main scan CCD 64 is set to perform image reading (main scan), and the photosensitive material A (normal printing paper) is read. When a reproduced image was formed, the following results were obtained.

First, when the image is read in the entire image density range 2.15 which exceeds the measured density range of the main scan CCD 64, the measured density is lowered by decreasing the S / N ratio and the spatial resolution of the main scan CCD 64. Since the image was read while expanding the range, the reproduced image obtained had low color and density reproducibility, and the image was so-called coarse particles as a whole. In addition, since the image density range of the film used when printing directly from the negative film to the photographic paper is usually about 1.1 to 1.2, image recording is performed on the photographic paper within the image density range of 2.15. In that case, the contrast of the image is about half of that in the normal direct printing, resulting in a blurred image without sharpness.

On the other hand, when a reproduced image is formed by selecting an image density range of about 1.2 from the image density range 2.15 of the entire image, whether the high density side or the low density side is selected. As a result, the density of the reproduced image changed, and the reproduced image obtained had poor color and density reproducibility as compared with the image printed directly.

On the other hand, when the main scan is performed using the image density range 1.42 of the central areas S1 to S9 of the image, the reproduced image close to the image by direct printing with good color and density reproducibility. I was able to get In particular, the image density range 1.18 of the central region obtained by over-averaging
When the main scan was performed, it was possible to mitigate the adverse effects of direct incidence and specular reflection of light from the light source, dust and scratches, and to stably obtain a high-quality reproduced image.

In recent years, compact cameras with a strobe automatic light emission function and films with lenses have become popular,
Along with this, the proportion of stroboscopic photography has increased to reach 35 to 40% of the total number of photography. Here, 25 to 30% of the images obtained by the flash photography are overexposed, and the images have a wide image density range in which the difference between the main subject density and the background density is large. That is,
Even if you consider only flash photography, about 10
% Exceeds the density range that can be properly read by the main scan. On the other hand, by using the image reading method of the present invention, it is possible to preferably perform image reading even on a negative film that is overexposed as described above, so that a high-quality reproduced image (output print) can be stably obtained. Can be made.

Although the image reading method of the present invention has been described above in detail, the present invention is not limited to the above-described embodiments, and various improvements and changes may be made without departing from the gist of the present invention. Of course. Further, although the above description has been made by taking the image reading of a negative film or a positive film as an example, the image reading method of the present invention can be suitably used for reading an image of a printed matter or a photograph.

[0081]

As described in detail above, according to the image reading method of the present invention, an original image in which the density range of the recorded image such as a film obtained by stroboscopic photography is unreasonably wide. Also, it is possible to realize highly accurate image reading in which image information necessary for obtaining a high-quality output image is surely read, and it is possible to stably obtain a high-quality output image.

[Brief description of drawings]

FIG. 1 is a diagram conceptually illustrating an example of a digital photo printer that implements an image reading method of the present invention.

FIG. 2 is a diagram conceptually showing an example of an image division mode in the image reading method of the present invention.

3 is a schematic perspective view conceptually showing a part of the image forming apparatus of the digital photo printer shown in FIG.

4 is a chart conceptually showing operation timing of the digital photo printer shown in FIG. 1. FIG.

[Explanation of symbols]

10 Digital Photo Printer 12 Image Reading Device 14 Setup Device 16 Image Forming Device 18 Prescan Unit 20 Main Scan Unit 22 Prescan Calculation Storage Unit 24 Reading Control Unit 26 Main Scan Control Unit 28 Amplifier 30 A / D Converter 32 CCD Correcting Unit 34 Density converter 36 Magnification converter 38,50 Light source 44,62 Imaging lens 46 Prescan line CCD (prescan CC
D) 52 filter section 54 condensing section 64 main scan line CCD (main scan CCD) 70 first selector 72a, 72b, 72c frame memory 74 second selector 76 setup calculation storage section 78 color gradation correction display control section 80 display Reference numeral 82 Input means 84 Color correction section 86 Gradation correction section 88 Timing selector 90 Output timing control section 92 D / A converter 94 AON driver 96 Polygon mirror 98 Image exposure section 100 Developing section 102 (102R, 102G, 102B) Light source 104 (104R) , 104G, 104B) Acousto-optic modulator (AOM) 106 fθ lens 108 Sub-scanning means 112 Coloring and developing tank 114 Bleaching and fixing tank 116a, 116b, 116c Washing tank 118 Drying section A Photosensitive material P Finished print

Claims (3)

[Claims] 1. When reading an image carried on the original by reading the reflected light of the original or the transmitted light of the original with a photoelectric conversion element, the photoelectric conversion element of the image carried on the original has a wide measurement density range. If the difference between the maximum image density and the minimum image density of the image density obtained by this pre-reading is within the measurement density range of the photoelectric conversion element in the main reading, the maximum image in the pre-reading is performed. When the density from the density to the minimum image density is set to the reading density range in the main reading, and the difference between the maximum image density and the minimum image density obtained by the pre-reading exceeds the measurement density range of the photoelectric conversion element in the main reading, An image reading method characterized in that a reading density range in main reading is set based on an image density in a central area of the image. 2. From 30 to 60 of the entire image from the center of the image
The image reading method according to claim 1, wherein a region of% is a central region of the image. 3. The measurement density range in main reading is set by weighting image density data closer to the center of the image with higher weighting in the central area of the image.
Or the image reading method described in 2.