JPH1153535A - Method and device for image reproduction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a reproduced image of high picture quality having no false contour without depending upon a source image by performing a dynamic range compression and expansion processing of a source image for a digital image signal according to an out-of-focus image signal. SOLUTION: The density converted digital image signal of an image photographed on a film A is sent as input image information to an image processor 14. An image reader 12 inserts color filters of R, G, and B of a color filter plate 28 in order to read the image by primary-color decomposition and stores images by the color in a frame memory 38. An image process condition setting part 40 sets image process conditions including the calculation of a density dynamic range and its compression/expansion rate by using the stored input image information. Then an image processing part 42 reads image information out of the frame memory 38 and performs a specific image processing including the dynamic range compressing and expanding processing according to the set image processing conditions to obtain output image information for the output of a print P by an image recording device 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing and displaying, as a visible image, an image signal obtained from a color image carried on a reflective original such as a photograph or a printed matter, or a transparent original such as a negative film or a reversal film. Image reproducing method and apparatus.

[0002]

2. Description of the Related Art In recent years, image information recorded on a photographic film (hereinafter, referred to as a film) such as a negative film or a reversal film or a printed matter is photoelectrically read, and the read image is converted into a digital image signal. Various image processing is performed to obtain digital image information for recording, and a photosensitive material such as photographic paper is scanned and exposed by a recording light modulated in accordance with the image information to record an image (latent image) and developed. A digital photo printer for printing has been proposed, and is currently in practical use by the present applicant.

Such a digital photo printer basically includes an image reading device that photoelectrically reads an image recorded on a film, an image reading device that performs desired image processing on the read image, and determines exposure conditions for image recording. The image reproducing apparatus includes a processing device and an image recording device that scans and exposes a processed image on a photosensitive material according to the determined exposure condition, performs a developing process, and reproduces a visible image.

In a digital photo printer, a read image is converted into a digital image signal. Therefore, the layout of a print image such as the synthesis of a plurality of images and the division of an image, the editing of characters and images, the color / density, etc. Various image processing such as adjustment, scaling, and contour emphasis can be freely performed, and a finished print that has been freely edited and subjected to image processing can be output according to the application. In addition, since the finished print image can be stored as image information on a recording medium such as a floppy disk, there is no need to prepare a film or print as a manuscript at the time of additional printing, and it is not necessary to determine exposure conditions again. Therefore, work can be performed quickly and easily. In addition, with conventional direct exposure printing,
Due to restrictions on resolution, color / density reproducibility, etc., it is not possible to reproduce all images recorded on film etc.
According to the digital photo printer, a print in which almost 100% of the image (density information) recorded on the film is reproduced can be output.

However, the photographing conditions of the image photographed on the film are not constant, and there are cases where the difference between light and dark (density) is large, that is, the luminance range of the image, that is, the dynamic range is very wide, such as flash photography or a backlight scene. is there. However, in general, the dynamic range (luminance range) of a subject image in which a photosensitive material such as photographic paper for reproducing an image carried on a film can be recorded is relatively wide,
Since the maximum density of the photosensitive material is limited, the dynamic range (luminance range) of a subject image recordable on a film is narrower.

For this reason, when a film image having a wide dynamic range as described above is exposed to an ordinary photosensitive material to produce a finished print, either a bright portion (highlight) or a dark portion (shadow) is destroyed. In some cases. For example, when a person is photographed in backlight, exposure is performed so that the person has a clear image.Bright parts such as the sky fly white, and conversely, exposure is performed so that the sky has a clear image. If you do, the person will be crushed black.
In order to solve this problem, in a conventional photoprinting apparatus,
Methods such as dodging and masking printing are used.

Dodging gives a normal exposure to an area of intermediate density in a scene, and selectively gives a long-time exposure using a perforated shielding plate to an area which is likely to be white on a print. By using a shielding plate to selectively shorten the exposure time in areas that are likely to be blackened on the print, the contrast of each subject is maintained, and a print without bright and dark areas is obtained. is there. As described above, a method of printing by overlaying the original film and the blurred image film using a photographic image of a blurred image obtained by inverting the negative / positive of the original film as the shielding plate for locally controlling the exposure time is known. Proposed. In addition, by partially changing the brightness of the illumination light source of the original photo,
A masking printing method capable of obtaining the same effect as dodging has also been proposed.

However, in a conventional photoprinting apparatus, such a method of performing dodging or masking printing requires an extremely advanced technique because a prepared shielding plate is operated irrespective of an image to be reproduced. In addition, it takes much time and effort to produce a blurred image film, resulting in extremely low printing efficiency. For this reason, the present applicant has proposed a dynamic range compression technique in a digital photo printer that can achieve the same or better effects as dodging or masking printing of a conventional apparatus. And No. 8-166646.

[0009] The technique proposed in Japanese Patent Application No. 7-165965 creates a blurred image with respect to a color original image,
A difference signal is obtained by subtraction between the corresponding pixels of the original image and the blurred image, a predetermined image processing is performed on the difference signal, and the difference signal is reproduced as a visible image. . According to this technique, since the blurred image of the original image represents only a structure having a low spatial frequency in the color image, the difference signal obtained by subtracting this blurred image signal from the digital image signal of the original image Is that the high frequency component in the original image has a signal value substantially the same as the original image signal, but the low frequency component has a smaller signal value than the original image signal, and the contrast of the entire image is weakened. However, a visible image is reproduced in which the local contrast represented by the high frequency component is substantially the same as the original image. Therefore, since the fine contrast in the bright part and the dark part remains, there is an effect that an image in which both the bright part and the dark part are not destroyed can be obtained.

[0010] The technique proposed in Japanese Patent Application No. 7-337509 discloses a method of creating a blurred image by filtering an original color image with an IIR filter.
The dynamic range compression processing of the original image signal is performed based on the blurred image, and the compression ratio in the dynamic range compression processing is calculated from the histogram of the original image. According to this, the IIR filter is used as a filter for creating a blurred image signal and the weighting sequence of the filtering process is shortened, so that the dynamic range compression process is performed without increasing the size of the device, and the image of the bright portion and the dark portion is reduced. There is an effect that the image quality of the reproduced image can be improved without being collapsed, and the image quality of the reproduced image can be improved even in a portion where the large area contrast is weak. However, the above-described automatic dodging techniques disclosed in Japanese Patent Application Nos. 7-165965 and 7-337509 perform the compression processing of the dynamic range by the same method, so that the contour portion having a large contrast can be obtained. There is a problem that false contours may occur.

On the other hand, the technique proposed in Japanese Patent Application No. 8-16646 is to produce a blurred image by a median filter on a color original image, and to subtract the difference signal between corresponding pixels of the original image and the blurred image. And subjecting the difference signal to predetermined image processing to reproduce the difference signal as a visible image. This technique has solved the above-mentioned problem of false contours to some extent by using a median filter.However, any of the techniques mentioned here are intended for high-contrast images, and have a dynamic range of the original image. There is a problem that an image having a low contrast, for example, such as a cloudy day, is not taken into account because the compression process is based on the basic principle.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an image having a high contrast and a large dynamic range, such as a backlit or strobe photographed image, even when the image is cloudy. Image reproduction that can obtain a high-quality reproduction image that is stable and appropriate without false contours regardless of the state of the original image, even if the image has a low contrast and a small dynamic range, such as a captured image. A method and apparatus are provided.

[0013]

According to the present invention, there is provided an image reproducing method for reproducing a digital image signal representing a color original image as a visible image. A filtering process using a stored smoothing filter is performed to create a blurred image signal representing a blurred image of the original image, and a dynamic range compression / expansion process of the original image is performed on the digital image signal based on the blurred image signal. To obtain a processed image signal, and to reproduce the processed image signal as a visible image.

Here, a histogram of the original image is created from the digital image signal, a dynamic range of the original image is calculated based on the histogram, and a dynamic range corresponding to the digital image signal is calculated based on the dynamic range. It is preferable that a compression / expansion rate is set, and the dynamic range compression / expansion processing is performed based on the dynamic range compression / expansion rate. Preferably, the dynamic range compression / expansion processing is performed based on a dynamic range compression / expansion rate of the dynamic range compression / expansion processing selected according to the scene of the original image.

It is preferable that the blurred image signal is created using a median filter as a smoothing filter that preserves the edge. Alternatively, it is preferable to create the blurred image signal using a median filter and a low-pass filter as the smoothing filter that preserves the edge. Further, it is preferable that the blurred image signal is a signal obtained by performing a sum average of a first blurred image signal obtained by the median filter and a second blurred image signal obtained by the low-pass filter.

It is preferable that the second blurred image signal by the low-pass filter is created by interpolating a thinned-out signal of the digital image signal of the original image. Preferably, an IIR filter is used as the low-pass filter. Preferably, the digital image signal is converted into a light / dark signal, and the blurred image signal is generated based on the light / dark signal.

According to the present invention, there is provided an image reproducing apparatus for reproducing a digital image signal representing a color original image as a visible image, wherein the digital image signal is passed through a smoothing filter in which edges are stored, and the blur of the original image is blurred. A blurred image signal generating means for generating a blurred image signal representing an image, and a dynamic range for performing a dynamic range compression / expansion process of the original image on the digital image signal based on the blurred image signal to obtain a processed image signal It is an object of the present invention to provide an image reproducing apparatus comprising compression / expansion processing means and reproducing means for reproducing the processed image signal as a visible image.

Here, the dynamic range compression / expansion means creates a histogram of the original image from the digital image signal, calculates a dynamic range of the original image based on the histogram, and calculates a dynamic range of the original image based on the dynamic range. It is preferable that a dynamic range compression / expansion rate is set according to the digital image signal, and the dynamic range compression / expansion processing is performed based on the dynamic range compression / expansion rate. Alternatively, it is preferable that the dynamic range compression / expansion unit performs the dynamic range compression / expansion processing based on a dynamic range compression / expansion rate of the dynamic range compression / expansion processing selected according to the scene of the original image.

It is preferable that the blurred image signal creating means creates the blurred image signal using a median filter as a smoothing filter which preserves the edge. Alternatively, it is preferable that the blurred image signal creating means creates the blurred image signal using a median filter and a low-pass filter as a smoothing filter that preserves the edge. Also, the blurred image signal creating means may convert the blurred image signal into a first blurred image signal by the median filter and a second blurred image signal by the low-pass filter.
It is preferable to calculate the sum of the blurred image signal and the blurred image signal.

It is preferable that the blurred image signal generating means generates the second blurred image signal by the low-pass filter by interpolating the thinned-out digital image signal of the original image. In addition, it is preferable that the blurred image signal creating means uses an IIR filter as the low-pass filter. Further, it is preferable that the blurred image signal generating means includes a converting means for converting the digital image signal into a light and dark signal, and a means for generating the blurred image signal based on the light and dark signal.

The median filter comprises a median filter for outputting a plurality of intermediate values having different levels, and the level of the intermediate value is selected according to the signal distribution of the digital signal for producing the blurred image signal. Is preferred. It is preferable that the median filter includes a plurality of median filters having different sizes, and the size of the median filter is selected according to a signal distribution of the digital signal that creates the blurred image signal.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reproducing method and apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a schematic view of an embodiment of the image reproducing apparatus of the present invention for implementing the image reproducing method of the present invention.
FIG. 2 is a schematic perspective view of an embodiment of an image recording apparatus that outputs a print image as a visible image in the image reproducing apparatus shown in FIG. As shown in FIG. 1, an image reproducing apparatus 10 of the present invention is configured as a digital photo printer, and includes an image reading apparatus 12 that photoelectrically reads a color original image photographed on a film A serving as a document. An image processing device 14 that performs digital image processing on a digital image signal read by the image reading device as input image information, and outputs an image-processed image signal for reproduction as a visible image as output image information; An image recording device 16 for reproducing the processed image signal output from the image processing device 14 on the photosensitive material Z as a visible image (hard copy image)
(See Fig. 2 for details) and visible image (soft copy image)
And a CRT 18 to be displayed on a display screen.

The image reading device 12 used in the present invention comprises:
A device for photoelectrically reading an image photographed on a film A, comprising a light source 20, a variable diaphragm 22 for adjusting the amount of light emitted from the light source 20, and a light source
It has three color filters of R, G and B for converting the image photographed on the film A into three primary colors of RGB by converting into three primary colors of (red), G (green) and B (blue). A color filter plate 24 for rotating and applying an arbitrary color filter to the optical path; and a light filter plate 24 for diffusing light transmitted through the color filters of the color filter plate 24 and uniformly entering the film A in the plane direction. Diffusion box 26 and film A
An imaging lens 28 for forming an image of the reading light transmitted through the CCD sensor 30 on the CCD sensor 30 and an area sensor for photoelectrically reading one image (one frame) of the film A formed by the imaging lens 28. A CCD sensor 32, an amplifier 32 for amplifying image signals of three colors RGB read by the CCD sensor 30, an A / D converter 34 for A / D converting the amplified image signal, and a digital image signal obtained. l
a first LUT (lookup table) 36 for performing og conversion into a density signal.

In such an image reading device 12,
An image captured on the film A is emitted from the light source 20, the light amount is adjusted by the aperture 22, the color is converted through the color filter plate 24, and the reading light diffused by the diffusion box 26 is transmitted through the film A. Is obtained. The projection light forms one image (one frame) of the image of the film A on the light receiving surface of the CCD sensor 30 by the imaging lens 28, and is photoelectrically read by the CCD sensor 30. An output signal from the CCD sensor 30 is amplified by an amplifier 32, converted into a digital signal by an A / D converter 34, converted into a density signal by an LUT 36, and converted into a density-converted digital image signal of an image photographed on the film A. It is sent to the image processing device 14 as input image information. The image reading device 22 performs such image reading by sequentially inserting the R, G, and B color filters of the color filter plate 28 into three.
Times, the image captured on film A becomes R,
The input image information can be obtained by separating the image into three primary colors of G and B and reading the image. The image reading method of the image reading apparatus used in the present invention may be a method of relatively moving a line sensor instead of the area type CCD sensor 30, or a method of spot metering like a drum scanner. .

The image processing apparatus 14 used in the present invention comprises:
A frame memory 38 that stores digital image signals of three colors R, G, and B supplied from the image reading device 12 as input image information for each color; and input image information stored in the frame memory 38. And an image processing condition setting unit (hereinafter referred to as a condition setting unit) 40 for setting various image processing conditions (setup; including calculation of a density dynamic range and a compression / expansion ratio thereof in the present invention) using And an image processing section (section) 42 for performing each image processing including a dynamic range compression / expansion process also characterized by the amount of the present invention according to the image processing conditions.

The digital image signals of three colors of RGB of one frame image of the film A read by the image reading device 12 are stored in the frame memory 38 for each color, read out, and read out by the condition setting section 40 and the image forming apparatus. The data is sent to the processing unit 42. The condition setting unit 21 includes a setup (processing condition setting) unit 44, a key input unit 46, and a parameter integration unit 4.
8 is provided. The setup section 44 is a section for setting image processing conditions serving as a basis. The setup section 44 has a CPU and the like, and generates image density histograms from image information (digital image signals) stored in the prescan memory 38 by an auto setup algorithm. Calculation of the density, minimum density, and dynamic range are performed to set the compression / decompression ratio of the dynamic range, and the color / density processing conditions and the like are determined by a known method using a matrix operation, an image processing algorithm, an image processing table, and the like. Set image processing conditions,
More specifically, various conversion tables, correction tables,
Create or adjust processing tables, etc.

First, the creation of the density histogram, the calculation of the dynamic range, and the setting of the dynamic range compression / expansion rate performed by the setup section 44 will be described. The setup unit 44 first reads out one frame of the image signal from the frame memory 38 and creates a density histogram by the auto setup algorithm. At this time, in order to speed up and simplify the density histogram creation processing and reduce the size of the processing circuit, the image signal read from the frame memory 38 is thinned out by a thinning processing means (not shown) such as a read timing controller (reading). The data may be supplied to the set-up unit 44 and a density histogram may be created from the decimated image signal. In the setup unit 44, density histograms are also created for each of the three colors of RGB. The density histograms of these colors are stored in the various tables described above, for example, a gray balance adjustment table of the second LUT 50 described later. These various tables will be described later.

In the setup section 44, these RGB
Using the three color density histograms, as shown in FIG.
A density histogram for the whole, that is, for light and dark (gray density) is created. Here, a method of obtaining the entire (gray) density histogram includes a method of taking an average of each of the RGB histograms, a method of converting each of the RGB components into brightness and luminance, and the like. As a method of converting into luminance, for example, there is a method of calculating a Y component defined by YIQ by the following equation. Y = 0.3R + 0.59G + 0.11B

In this manner, as shown in FIG. 3, it is assumed that density histograms for three types of luminance Y have been obtained for frames of three different scenes. Here, the image in which the density histogram a indicated by the solid line is obtained is an image having a high frequency of intermediate density and having a general pattern (scene).
Code _{DR o (= Y max o -Y} min o) a standard scene density dynamic range present in the finished print reproduction region of the light-sensitive material Z of the photographic paper and the like represented by the (in this case in FIG. 3, the standard density range concentration than) that the dynamic range _{DR a (= Y max a -Y} min a) is an image at a wide fine weather. On the other hand, the density histogram b indicated by the one-dot chain line indicates that the frequency of the intermediate density is low, the frequency in the high density area and the low density area is high, and the contrast is high. _{b
(= Y max b -Y min b} ) has spread beyond the standard density range DR _o, this remains high density portion (dark portion) is blackened when printed, it low density portion (bright portion) is the image to fly white Is shown. On the other hand, the density histogram c indicated by the broken line shows that the image has only a middle density, has very low high and low densities, and has low contrast.
The dynamic range DR _c (= Y _{max c} −
Y _{min c} ) is smaller than the standard range DR _o . For example, it indicates that the image is cloudy.

Therefore, according to the present invention, in order to stably obtain an appropriate finish regardless of whether the image has a high contrast or an image having a low contrast, the images represented by the density histograms a and b have a dynamic range. , And the image represented by the density histogram c needs to be expanded in the dynamic range. Therefore, in the present invention, the maximum density (Y _max ) and the minimum density (Y _min ) are calculated from the density histogram, the difference between them is calculated, and DR (= Y _max −Y _min ) is calculated in the density dynamic range. Using the density dynamic range DR thus obtained, a dynamic range compression / expansion rate (hereinafter referred to as an expansion / contraction rate) α is calculated according to the following equation. α = 1−DR _o / DR Here, DR _o is an average density dynamic of dozens of scenes that can be reproduced within the print reproduction area of the target photosensitive material, and the average of these dozens of scenes a standard concentration range determined from the difference between the maximum density (Y _{max o)} as the lowest concentration determined from a histogram of concentration (Y _{min o).}
Note that when the expansion ratio α <0, the color original image is compressed, and when the expansion ratio α> 0, the color original image is expanded.

As described above, in the setup section 44, the expansion / contraction ratio α is automatically calculated by the auto setup algorithm. In the present invention, the operator visually observes and judges the scene of the color original image and determines the dynamic range. May be determined by the key input unit 46. Key input section 46
Calculates the correction amounts of various image processing conditions including the above-described expansion and contraction rate α in accordance with the key input by the operator using the adjustment key 47 shown in FIG. With the adjustment key 47 in the illustrated example, as an example, the overall density (D), the cyan (C) density,
Magenta density (M), yellow (Y) density, gradation (γ), expansion rate (α) of overall density dynamic range DR, expansion rate (α _l ) of bright part (highlight side), and dark part (shadow) the ratio of expansion and contraction of the side) a (alpha _d), can be adjusted respectively.

The operator performs the verification while viewing the image displayed on the monitor 18 described later, and adjusts the image to a desired state by pressing the (+) key and (-) key of each parameter as necessary. That is, the image processing conditions can be adjusted. Each correction amount is
It is adjusted according to the number of times the key is pressed. In addition to the key operation, the operator performs a display corresponding to the adjustment key 47 on the monitor 18 as shown in FIG. 1, for example, displays a GUI (slider), and displays a mouse 66
Alternatively, a method of performing adjustment by keyboard operation may be used.

The parameter integration section 48 is provided with the image processing conditions set by the setup section 44 and the key input section 4.
And the correction amount obtained in Step 6 is integrated into the finally set image processing condition. Therefore, when there is no input from the adjustment key 47, the image processing conditions finally set here are the image processing conditions set by the setup unit 44. Further, the parameter integration unit 48 integrates and sets the image processing conditions, and sets a predetermined location (the LU) of the image processing unit 42.
T50, 60 and MUL 56), and each image information is processed according to the image processing conditions.
Accordingly, when an input is made from the adjustment key 47 and the image processing condition previously set by the parameter integration unit 48 is changed, the display image on the monitor 18 also changes accordingly.

The condition setting unit 40 is configured as described above. However, when the adjustment by the operator is performed by operating the mouse 66 or the like of the GUI on the display screen of the monitor 18,
The key input unit 46 may be omitted, or the output by the GUI may be output from the setup unit 44 instead of the parameter integration unit 48.
In the case where the parameter is directly reflected in the parameter, the parameter integration unit 48 may be omitted.

On the other hand, the image processing section 42 is the most characteristic part of the present invention. The image processing section 42 reads out the image information stored in the frame memory 38 and performs predetermined processing according to the image processing conditions set by the condition setting section 40. A part that performs image processing and becomes output image information for print P output by the image recording device 16, and includes a second LUT 50, a matrix calculator (MTX) 52, a filter (FIL) 54, and a multiplier (M
UL) 56, a subtractor 58, and a third LUT 60.

The second LUT 50 reads the input image information stored in the frame memory 38 and performs gray balance adjustment, brightness correction and gradation correction. It is configured. Each correction (adjustment) table of the second LUT 50 is set or adjusted by the parameter integration unit 48 of the condition setting unit 40 described above.

FIG. 5 shows an example of a table set in the second LUT 50. FIG. 5A shows a gray balance adjustment table. The setup unit 44 creates this adjustment table by obtaining a gray balance from the calculated maximum density and minimum density by a known method. When an input is made from the above-described adjustment key 47, a correction amount is calculated by the key input unit 46, and the correction amount and the adjustment table created by the setup unit 44 are integrated by the parameter integration unit 48. The inclination of each of the R, G, and B tables of the adjustment table changes. FIG. 5B shows a correction table for brightness correction. The setup section 44 creates this correction table from the created density histogram and the highest and lowest densities using a known setup algorithm. Also, this correction table is adjusted as shown in FIG. 5B by inputting the density (D) key of the above-mentioned adjustment key 47, similarly to the gray balance adjustment table. FIG. 5C shows a gradation correction table, which is a setup unit 44.
Creates this correction table from the created density histogram and the highest and lowest densities using a known setup algorithm. Further, this correction table is obtained by inputting the gradation (γ) key of the adjustment key 47 as shown in FIG.
Is adjusted as shown in

The MTX 52 is a matrix arithmetic unit that performs color correction of the RGB three-color image signals processed by the second LUT 70. A matrix operation set according to the spectral characteristics of the photosensitive material (photographic paper) Z, the characteristics of the development processing, and the like is performed to perform color correction.

The image signal subjected to the color correction processing by the MTX 52 is sent to both a subtractor 58 and a filter (FIL) 54 for generating a blurred image signal for performing a dynamic range compression / expansion processing. When the dynamic range compression / expansion processing is not performed, the MTX 52 and the third LUT 60 are connected by bypass, and no blurred image signal is generated. The presence or absence of the compression / expansion processing in this dynamic range may be set by a mode selection based on an operator's input, a method of judging from a calculation result in the condition setting unit 40, or the like.

The FIL 54 is a filter for smoothing only high-frequency components while leaving edges, and two-dimensionally blurs RGB three-color image signals color-corrected by the MTX 52 while retaining edges for each color. , For obtaining a blurred image signal of a color original image. As the FIL 54 used in the present invention, any filter may be used as long as it is a smoothing filter that preserves edges. For example, a median filter (MF) can be used. Here, the median filter is a blur mask filter for preserving a large edge in an image signal and blurring a fine structure two-dimensionally, and has a characteristic as shown in FIG. Here, if the window size (that is, the blur mask size) is too small, a blur mask having fine structure shading remains. On the other hand, if the window size is too large, the effect of the blur mask does not appear so much when the main subject is small. However, there is a disadvantage that the amount of calculation increases and the scale of the device increases. As a result of experiments on various scenes by the present applicant, the window size in the case of 135 film is preferably about 20 × 20 to 5 × 5.

As the FIL 54, a median filter (M
F), the conventional low-pass filter (L
PF) to extract only the low-frequency components of the original image, and to generate the blurred edge portion and the occurrence of false contour (overshoot) which occur when the original image is two-dimensionally blurred to obtain a blurred image signal. Thus, it is possible to obtain an image in which noise (high-frequency components) in a flat portion has been cut while preserving edges. By the way, if a median filter is used as the FIL 54, the edge can be preserved and smoothed. However, as described above, if the mask size is not appropriately selected, the blur mask as the smoothing filter with the preserved edge is used. The effect may not be fully obtained.

Therefore, the FI used in the present invention
As L54, it is preferable to use both a median filter (MF) and a low-pass filter (LPF) as shown in FIG. The FIL 54 shown in FIG. 7 includes a median filter (MF) 54 a for performing blur mask processing on the image signal color-corrected by the MTX 52 to obtain a blur mask signal 1 in which a large edge of an original image is preserved and a fine structure is blurred.
A low-pass filter (LPF) 5 for extracting only the low-frequency component of the same image signal color-corrected by the MTX 52 and obtaining a blur mask signal 2 which is a two-dimensional blur of the original image
4b, the blur mask signal 1 by the MF 54a and the LPF 5
And a calculation processing means 54c for generating a blur mask signal by weighting and adding the blur mask signal 2 of FIG. 4b. Thus, MF54a and LP as FIL54
By using together with F54b, it is possible to sufficiently preserve the edge information and to pick up only the information of the very low frequency component.

Here, the LPF 54b used in the present invention
FIR (Finit (Finit)
e Impulse Respones) type low-pass filter may be used. However, IIR (Infinite Impulse Respones) can be used because a small circuit can generate large blurred image information.
es) It is preferable to use a low-pass filter of the type. FIG.
Shows an example of an IIR low-pass filter. The low-pass filter in the illustrated example has a configuration in which an adder is arranged in the forward direction and a delay circuit is arranged in the feedback direction. In addition, II which can be used in the present invention
An R-type low-pass filter is disclosed in Japanese Patent Application No. 7-337509 filed by the present applicant.
An R-type low-pass filter can be used.

The R generated by the FIL 54 in this manner is
The blur mask signal of each of the three colors GB is multiplied by a multiplier (MUL).
Sent to 56. The MUL 56 sets the blur mask signals of the three colors RGB in the condition setting unit 40 for each color.
The dynamic range compression and expansion ratio α being sent by performing an arithmetic operation of multiplying the multiplier, is for obtaining a blurred image signal S _B.

The density area of an image that can be photographed on the film A is generally wider than the reproduction area in the finished print, and an object having various density ranges has various density dynamic ranges (DR) on the film A. You can shoot as. For example, some images have a wide density dynamic range, such as images in fine weather,
Some images have a narrow density dynamic range, such as images on a cloudy day, and others have a wide dynamic range and high contrast. Also, in the case of an image with a density range that is far beyond the reproduction range of the finished print, such as in a snow scene, a backlight scene, or an image captured with a strobe, such as a bright portion (highlight) side or a dark portion (shadow) side. There is also. Further, the exposure state of the film A is not always appropriate, and there are many so-called under / over exposures.

As shown in FIG. 3, in the image in which the density histogram created by the set-up section 44 from the image information of the film A is shown by the curves a and b, the density dynamic range DR has the standard density corresponding to the print reproduction area. for wider range DR _o, not can be reproduced all the pixels in the finished print, (signal strength weak read) high density portion beyond the standard density range corresponding to the gamut i.e. turns black crushed dark portion of the pixel ( In the finished print, the bright part is skipped. Conversely, the pixels in the low-density part exceeding the standard density range, that is, the pixels in the bright part, become white (in the finished print, the dark part is lost). Therefore, in order to obtain a reproduced image of all of the original image, and compressing the dynamic range of the original image, it is necessary to match the standard density range DR _o corresponding to reproduction range of finished prints. On the other hand, in the image represented by the histogram curve c in FIG. 3, the concentration dynamic range DR is narrower than the standard concentration range DR _o, poor spots white and poor denseness of black, without contrast, with no sharp because would be reproduced as an image, by extending the dynamic range, it is necessary to match the standard density range DR _o.

When the frequency of image information on the bright part (highlight) side is high, such as in a snow scene or a backlit scene, the entire dynamic range can be reduced by strongly compressing the dark part (shadow) side in particular. If the compression is effective or if the image information on the dark side (shadow) is high like a flash image, the bright part (highlight)
In some cases, it may be advantageous to compress the entire dynamic range by strongly compressing the sides. As described above, preferably, the dynamic range is compressed by adjusting the density of the light and dark portions without changing the gradation of the intermediate density portion so as to provide the same effect as the dodging by the conventional direct exposure. It may be better to process the image information in this way.

Further, when the image of the film A serving as the original is overexposed, the dark portion side is entirely black (in a finished print, the density is placed on the bright portion and white omission is poor).
Images tend to be sharp. Conversely, in the case of underexposure, the density on the bright side increases (the density of the dark area decreases in the finished print, and the tightness of black deteriorates), which tends to result in an image without sharpness. Therefore, in order to obtain a high-quality image at this time, it is necessary to raise the contrast by raising the gradation. Within the standard density range, the gradation of the dark part is raised in the case of overexposure, and the gradation is raised in the case of underexposure. In order to achieve this, it is necessary to extend the dynamic range so as to raise the gradation of the bright part. As described above, when correcting under / over exposure, it is sometimes preferable to extend the dynamic range without changing the gradation of the intermediate density portion.

As described above, in the present invention, the color original image can be subjected to the compression / expansion processing of the dynamic range according to the scene. For this purpose, as described above, the setup unit 44 of the condition setting unit 40 performs The dynamic range compression / expansion rate α can be automatically set appropriately according to the scene of the color original image, or the dynamic range compression / expansion rate α determined by the operator by visually checking the original image is input from the key input unit 46. You can also.
At this time, a part of the density dynamic range, particularly a bright part (highlight), such as a snow scene, a backlight scene, a strobe shooting scene, and an underexposure and an overexposure.
When the sides and dark portion (shadow) either one or both the partially compressed extension side is effective, set up these scenes scaling factor alpha _l and dark portion scaling factor alpha _d of the bright portion The unit 44 automatically determines and automatically calculates,
Or, the operator inputs from the key input unit 46, configured as a non-linear function scaling factor α and different other parts, the whole image density dynamic range DR may be fit within a standard concentration range DR _o .

In the illustrated example, a multiplier (MUL) 56 is used to multiply the blur mask signal by the expansion / contraction ratio α. However, the present invention is not limited to this. Good. In particular, when the expansion ratio α is given as a nonlinear function, it is preferable to use an LUT.
The method of compressing and expanding the dynamic range using the LUT is disclosed in Japanese Patent Application No. 7-337509 filed by the present applicant.
And the methods disclosed in JP-A-8-157200 can also be used.

[0052] Thus RGB3 colors each color unsharp image signals of which are dynamic range compression and expansion process in MUL58 S _B is sent to the subtracter 58. In the subtractor 58,
MTX52 by subtracting the color correction has been directly sent the original image of the RGB colors of the digital image signals S RGB color unsharp image signals generated by the MUL58 from _A S _B, respectively, by, obtaining a difference signal S _sub of each color Can be. Here, the subtracter 58, the original image signal S blur from the _A image signal S
Any subtraction means may be used as long as it can subtract _B, and may be configured using an adder or the like. The difference signal obtained in this way preserves the edges and high-frequency components, performs dynamic range compression / expansion processing only on the low-frequency components, reproduces an appropriate high-quality image with a standard density range and no false contours. This is an image signal that can be performed.

The difference image signal S _sub thus obtained is sent to the third LUT 60. The third LUT 60 is a subtractor 6
The image signal S _sub obtained by the subtraction by 0 is converted into an output image signal corresponding to the characteristics of a final output medium, for example, a photosensitive material such as photographic paper used in the CRT monitor 18 or the image recording device 16. It is a conversion table. Therefore, the image signal S _sub is gradation-converted by the third LUT 60 into an image signal corresponding to the final output medium, and is output to the image recording device 16 and the monitor 18 as output image information.

The image signal that has been subjected to gradation conversion and density conversion in the third LUT 60 in this manner is converted into a signal converter 62
And converted into a signal corresponding to the monitor 18 by the signal converter 62, and then input to the D / A converter 64 to be converted into an analog image signal and displayed on the monitor 18 as a visible image, or The image data is input to the image recording device 16 and the finished print image P
Is output as a visible image. Here, the image displayed on the monitor 18 and the finished print image sent to and reproduced by the image recording device 24 are obtained from exactly the same image signal that has been subjected to various image processing including dynamic range compression / expansion processing. Therefore, it is needless to say that the image is an appropriate high-quality image having the same dynamic range compression / expansion effect.

As described above, the operator can perform the verification by looking at the image displayed on the monitor 20.
If necessary, press each of the adjustment keys 47 to adjust the overall density, C density, M density, Y density, gradation, overall dynamic range compression / expansion, bright area compression / expansion, and dark area compression / expansion. To adjust the image recorded in the finished print. Adjustment key 4 by operator
7 is sent to the key input unit 46 and is used as a correction amount of the image processing condition including the expansion / contraction ratio α.
In step 8, the correction amount and the image processing condition including the scaling factor α set by the setup unit 44 are integrated, and a new image processing condition after key correction is set. That is, MU
The expansion / contraction ratios α, α _l , α _d supplied to L56, the correction table of the second LUT 50 and the third LUT 60
Is adjusted or reset by the key input with the adjustment key 47. As a result, the image displayed on the monitor 18 changes accordingly, and the finished print image P output from the image recording device 16 also changes.

By the way, like the monitor 18 shown in FIG. 1, the display screen displays the reproduced image together with the expansion / contraction ratios α, α _l , α _d
May be displayed as a GUI so that adjustment or resetting can be performed using the mouse 66 or the like. FIG.
Shows an example of the display screen of the monitor 18 on which the image subjected to the dynamic range compression / expansion processing is displayed. This monitor 18
Displays a processed image and displays a GUI (adjustment slider) 18a for adjusting the expansion / contraction ratio of the displayed image with a mouse 66 or the like, and determines the scene of the display image. And stretch ratio α,
Fine adjustment and resetting of α _l and α _d can be performed. The expansion and contraction rates α, α _l , and α _d adjusted in this manner are stored in the condition setting unit 4.
0 is input to the setup unit 44 or the parameter integration unit 48, and is finally set as a multiplier in the MUL 56 of the image processing unit 42. The image processing device 14 is basically configured as described above.

Next, the image recording device 16 outputs the third L of the image processing unit 42 of the image processing device 14 as output image information.
The UT 60 receives an image signal corresponding to the image recording of the finished print after the gradation conversion processing is completed, scans and exposes the photosensitive material Z by light beam scanning according to the output image information, and ends the exposed photosensitive material Z. And outputs the finished print image P as a visible image, as shown in FIG.
0 and a developing unit 92.

The image signal output from the image processing unit 42 of the image processing device 14 is transferred to a driver 88 and converted into an analog image signal by an internal D / A converter (not shown). The driver 88 modulates the scanning light beam of the image exposure unit 90 according to the D / A-converted analog image signal.
OM) 94 is driven.

On the other hand, the image exposure section 90 scans and exposes the photosensitive material Z by light beam scanning and records the image of the image information on the photosensitive material Z. As shown conceptually in FIG. A light source 96R for emitting a light beam in a narrow band corresponding to the exposure of the R photosensitive layer formed on the photosensitive material Z, a light source 96G corresponding to the exposure of the G photosensitive layer, and corresponding to the exposure of the B photosensitive layer. AOMs 94R, 94G, and 94 that modulate the light source of each light beam of the light source 96B, and the light beam emitted from each light source according to a recorded image.
B, a polygon mirror 98 as an optical deflector, an fθ lens 100, and a sub-scanning conveyance unit for the photosensitive material Z are provided.

The light beams emitted from the light sources 96 (96R, 96G, 96B) and traveling at mutually different angles are respectively transmitted to the corresponding AOMs 94 (94R, 94G, 96G).
94B). Each AOM 94 has a driver 88
R, G and B drive signals corresponding to the recorded image are transferred, and the intensity of the incident light beam is modulated according to the recorded image.

Each light beam modulated by the AOM 94 enters the polygon mirror 98 at substantially the same point, is reflected, is deflected in the main scanning direction (the direction of the arrow x in the drawing), and is then moved by the fθ lens 94 to a predetermined scanning position. The light is adjusted so as to form an image with a predetermined beam shape on z, and enters the photosensitive material Z. The image exposure unit 90 may be provided with a light beam shaping unit and a surface tilt correction optical system as needed.

On the other hand, the photosensitive material Z is loaded at a predetermined position while being wound in a roll shape and shielded from light. Such a photosensitive material Z is pulled out by a pull-out roller (not shown), and is held in the scanning position z while being held at the scanning position z by a pair of conveying rollers 102a and 102b disposed across the scanning position z constituting the sub-scanning means. Are conveyed in the sub-scanning direction (the direction of the arrow y in the figure) perpendicular to the scanning direction. Since the light beam is deflected in the main scanning direction, the entire surface of the photosensitive material Z conveyed in the sub-scanning direction is two-dimensionally scanned and exposed by the light beam, and the photosensitive material Z is applied to the image processing unit 40 of the image processing apparatus 14. The image (latent image) of the transferred image information is recorded.

The exposed photosensitive material Z is then conveyed to the developing section 92 by the pair of transport rollers 104, where it is subjected to a developing process to be a finished print P. Here, for example, if the photosensitive material Z is a silver halide photographic photosensitive material, the developing unit 92 includes a color developing tank 106, a bleach-fixing tank 108, and a washing tank 110.
a, 110b, 110c and 110d, a drying section, a cutter (not shown), etc., and the photosensitive material Z is subjected to predetermined processing in each processing tank, dried, and then corresponds to one print by the cutter. The print is cut into a predetermined length and output as a finished print P. The image recording device 16 is basically configured as described above.

The image reproducing apparatus 10 of the present invention is basically configured as described above. The operation and the image reproducing method of the present invention will be briefly described below with reference to the drawings. The image reproducing device 10 is started up, and in the image reading device 12, after the light amount of the light source 20 is stabilized and predetermined operations such as setting of the open reference value of the aperture 22 and temperature adjustment of the developing unit 92 are completed, the original image is read. When the film A is loaded at a predetermined position and an instruction to start printing is issued, first, reading of an image on the film A is started.

When reading is started in the image reading apparatus 12, the light is emitted from the light source 20, the light amount is adjusted by the aperture 22, and the color is adjusted by passing through the color filter plate 24 (for example, G
The reading light diffused by the diffusion box 26 passes through the film A, becomes projection light carrying a G image of the film A, is formed on the CCD sensor 30 by the imaging lens 28, and is photoelectrically Read. An output signal from the CCD sensor 30 is amplified by an amplifier 32 and the A / D
After being converted into a digital signal by the converter 34 and log-converted by the LUT 36 into a density signal, the image processing apparatus 1
4 and stored in the G image frame memory of the frame memory 38. Next, the color filter plate 30 is switched, the R filter acts on the optical path, the R image is read in the same manner, stored in the R image frame memory of the frame memory 38, and the B image is similarly read. The data is stored in the B image frame memory of the frame memory 38, and the reading is completed.

On the other hand, in the image processing apparatus 14, the setup section 44 of the condition setting section 40 reads the digital image signal from the frame memory 38 at the time when the reading by the image reading apparatus 12 is completed, and creates the density histogram and the maximum density. and minimum density and performs calculation and the like of the density range, such as to calculate or set the scaling factor alpha _l and dark portion scaling factor alpha _d of the dynamic range compression and expansion ratio alpha and bright portions, yet a 2LUT50 gray balance adjustment table, Brightness correction table and gradation correction table, and third L
A gradation conversion table for the UT 60 is created, image processing conditions are set, and the table is output to the parameter integration unit 48. The parameter integration unit 48 transfers the image processing conditions such as the expansion / contraction ratio α to the MUL 56 of the image processing unit 40 as a multiplier, and also transfers the image processing conditions to the LUTs 50 and 60 to set them as a table for image processing.

When the image processing conditions are set, the second LUT 50 of the image processing unit 40 reads out the digital image signals of the RGB colors of the original image from the frame memory 38, performs the processing according to the set tables, and then executes the MTX 52 Color correction is performed. The image signal S _A of each color of RGB, which has been color-corrected by the MTX 52, is subtracted for each color by the subtractor 58 and the FIL.
Sent to 54. The FIL 54 performs a filtering process by a median filter (MF) 54a on the transmitted image signal S _A for each color, and preferably, as shown in FIG. 7, a median filter (MF) 54a and a low-pass filter (LPF) The filtering processing by 54b and the arithmetic processing by weighting and adding means 54c are performed to generate a blur mask signal. The blur mask signal thus generated is sent to the condition setting unit 4 in the MUL 56.
The expansion / contraction ratio α sent from the parameter integration unit 48 of 0
(Α _l, α _d) is multiplied by the compression and expansion processing of the dynamic range is converted into the unsharp image signals S _B was made.

[0068] Thus the unsharp image signals S _B obtained in FIL54 is sent to the subtracter 58. In the subtractor 58, MT
From the image signal S _A processed in X52 to the blurred image signal S _B
Is subtracted to generate a difference image signal S _sub in which the dynamic range of the original image is compressed. The image signal S _sub output from the subtractor 58 is output to the monitor 1 in the LUT 60.
8, the image is subjected to gradation conversion so as to be an image corresponding to the display by 8,
The signal is converted into a signal corresponding to the display on the monitor 18 by the signal converter 62, converted into an analog signal by the D / A converter 64, and displayed on the monitor 18.

The operator performs verification by looking at the image displayed on the monitor 20, and makes various adjustments using the adjustment keys 47 as necessary. When there is an input from the adjustment key 47, the correction amount of the image processing condition such as the expansion ratio α is calculated by the key input unit 46, and the correction amount and the image processing condition set by the setup unit 44 are calculated by the parameter integration unit 48. Are integrated, and the image processing conditions are reset or changed. The new expansion / contraction ratio α is stored in the MUL 56 of the image processing unit 42,
Other new image processing conditions are transferred to the LUTs 50 and 60, the multiplier in the MUL 56 and the contents of the table set in the LUTs 50 and 60 are changed, and the image processing by the image processing unit 42 is performed again based on these. As a result, the image on the monitor 18 changes.

When the operator determines that the image is appropriate (OK), an output instruction is issued and the image processing apparatus 1
The digital image signal subjected to the dynamic range compression / expansion processing of each color of RGB from the LUT 60 of the image processing unit 42 of No. 4 is sent to the image recording device 16 as output image information. In addition,
The above verification need not always be performed. For example, a full auto mode or the like may be set, and a print may be automatically created by the image recording device 16 without verification.

When the image recording device 16 receives the digital image signal subjected to the dynamic range compression / expansion processing as the output image information, the processed digital image signal is input to the driver 88 and D / A converted into a recording analog image signal. . In the image recording device 16, a light beam is emitted from each light source 96, this light beam is modulated according to a recording image by each AOM 94 driven by a driver 88 according to a recording image signal, and is modulated by a polygon mirror 98 in the main scanning direction. The photosensitive material A conveyed in the sub-scanning direction via the fθ lens 100 is two-dimensionally scanned and exposed to form a latent image. The exposed photosensitive material A is placed in the color developing tank 1
06, a predetermined process is performed in the bleach-fixing tank 108 and the washing tank 110, and after being dried, it is cut into a predetermined length corresponding to one print (frame) by a cutter and output as a finished print P. The resulting print image P, whether a high-contrast image or a low-contrast image, has no false contours and no bright or dark portions collapsed, and the dynamic range is appropriately compressed and expanded. This is a high-quality image with a bend.

That is, as shown in FIG. 10, a feature of a preferable mode of the image processing in the image reproducing method of the present invention is that a density histogram is prepared in advance from an original image, a density range is calculated, and then a dynamic range compression / decompression rate α Is calculated, and a median filter (MF) is calculated from the original image.
Image 1 generated by the above and a low-pass filter (L
PF), a blurred image is generated by weighting and adding the blurred image 2 generated by PF), and then a compression / expansion rate is calculated using a compression / expansion rate α calculated in advance. By subtracting from, whether it is a high-contrast image or a low-contrast image,
An object of the present invention is to obtain a sharp, high-quality image without a dynamic range being appropriately compressed / expanded and without occurrence of false contours or collapse of bright or dark portions.

By the way, in the image reproducing apparatus 10 shown in FIG. 1, the image information can be processed only by reading the color original image from the film A once without performing the pre-scan. Although reading and processing can be performed quickly, the present invention is not limited to this, and pre-scanning may be performed.

The image reproducing apparatus 10A shown in FIG.
In addition to the configuration of the image reproduction device 10 and the image processing device 14A, specifically, the configuration of the image processing device 14, a pre-scan memory 68 and a pre-scan image processing unit 7
Since they have exactly the same configuration except that they have 0, the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

In the image reproducing device 10A shown in FIG. 1, the image reading device 12 performs a pre-scan for coarsely reading an image at a low resolution prior to image reading (main scan) for obtaining image information for output. Do. The image processing apparatus 14A sets (sets up) various image processing conditions from the image information obtained by the pre-scan, performs image processing on the image information of the main scan in accordance with the image processing conditions, and Output image information for image recording. The image reading method in the pre-scan and the main scan is basically the same, but the difference between the two is that
The only difference is that the resolutions of the read images are different. At the time of pre-scan, the image read by the CCD sensor 30 is:
The pixels are thinned out under the control of the timing controller 00 connected to the pre-scan memory 68 of the image processing device 14A, and are converted into coarse image information having a low resolution.
At 0, image processing is performed.

The illustrated image processing apparatus 14A performs various types of image processing including dynamic range compression / expansion processing on a digital image input from the image reading apparatus 12). In addition to a frame memory 38 used as a memory, an image processing condition setting unit 40, and an image processing unit 42 for a main scan image, a pre-scan memory 68 and a pre-scan image processing unit (hereinafter, referred to as a display image processing unit) 70 And The pre-scan memory 38 and the frame memory 68 include:
A timing controller 72 that controls reading of image information for each pixel is connected.

The image information of the pre-scan by the image reading device 12 is sent to the pre-scan memory 68 and the image information of the main scan is sent to the frame memory 68 and stored therein. The pre-scan memory 68 has basically the same configuration as the frame memory 38 which is a main scan memory, and stores the R image information, the G image information, and the B image information supplied from the image reading device 12 together. It is composed of three frame memories for storing each. Note that, if necessary, the pre-scan memory 68 and the frame memory 1
4 may have different recording capacities.

The image information stored in the prescan memory 68 is stored in the display image processing unit 70 and the condition setting unit 40, and the image information stored in the frame memory 38 is stored in the image processing unit 4
2, respectively. The condition setting unit 40 is different from the condition setting unit 40 of the image processing apparatus 14 shown in FIG. 1 in that the condition setting unit 40 receives the image information stored from the pre-scan memory 68, but the setup unit 44, the key input unit 46, And functions in exactly the same way in setting various image processing conditions such as calculation of a dynamic range and calculation of a compression / expansion rate α. The condition setting unit 4
The compression / decompression rates α, α _l , α _d, etc. calculated by the setup unit 44 of 0 are sent from the parameter integration unit 48 to the MUL 56 of the image processing unit 42, and are not only set as multipliers but also displayed by the display image processing unit It is also sent to the third LUT 78 of 70 and is set as a multiplier or a dynamic range compression / decompression table. Further, various other image processing conditions (including tables and the like) set by the setup unit 44 are transmitted from the parameter integration unit 48 to the second and third LUTs 50 and 60 of the image processing unit 42 and the display image processing unit 70. The second LUT 74 also sets various image processing tables and the like.

The display image processing section 70 reads out the pre-scan image information stored in the pre-scan memory 68,
The second LUT 74, the MTX 76, and the third LUT 78 perform various image processing in accordance with the image processing conditions set by the condition setting unit 40 and serve as image information for display on the monitor 18.
And a signal converter 62. Here, the second LUT 74
Has exactly the same function as the second LUT 52 of the image processing unit 42, reads out image information stored in the pre-scan memory 68, and performs gray balance adjustment, brightness correction, and gradation correction. The MTX 76 is the MT of the image processing unit 42.
It has exactly the same function as X52 and performs color correction of image information processed by the second LUT 74.

In the display image processing section 70, the MTX7
The image information processed in step 6 is directly input to the third LUT 78 without performing dynamic range compression / expansion processing using blurred image information by filtering processing (blurred mask processing). The third LUT 78 performs the same tone conversion function as the third LUT 60 of the image processing unit 42 when the prescan image information color-corrected by the MTX 76 is displayed on the monitor 18 without performing the dynamic range compression / expansion processing. And performs tone conversion and density conversion into image information suitable for displaying the color-corrected pre-scan image information on the monitor 18. On the other hand, when the dynamic range compression / expansion processing is also performed on the color correction pre-scan image information, the third LUT 78
Has a multiplication function or a magnification conversion function using the expansion and contraction ratios α, α _l , and α _d sent from the condition setting unit 40 in addition to such a gradation conversion function. The compression / expansion processing of the set expansion / contraction rates α, α _l , and α _d and gradation conversion and density conversion processing are performed to convert the image signal into an image signal having an appropriate dynamic range and suitable for display on the monitor 18.

The prescanned image information converted by the third LUT 78 is output and output to the signal converter 6.
2, the signal is converted into a signal corresponding to the monitor 18, further D / A converted by the D / A converter 64, and displayed on the monitor 18. Here, when the image displayed on the monitor 18 has been subjected to the dynamic range compression / expansion processing, the finished print image P sent to the image recording device 24 for reproduction and the various types of image processing and compression / expansion processing The same processing has been performed, and therefore, an image similar to the finished print image P is displayed on the monitor 18. In the example shown in FIG. 11, the mouse 66 connected to the monitor 18 is omitted.

The operator examines the pre-scan image displayed on the monitor 18 to perform verification, and presses each of the adjustment keys 47 of the condition setting section 40 as necessary to make various adjustments. As described above. The key input of the adjustment key 47 by the operator is sent to the key input unit 46 of the condition setting unit 40 and is used as the correction amount of the image processing condition. The correction amount and the image set by the setup unit 44 are set in the parameter integration unit 48. The processing conditions are integrated, and new image processing conditions after key correction are set. Here, by the key input by the adjustment key 47, the image processing unit 42 adjusts or resets each correction table of the second LUT 50, the multiplier α of the MUL 56, and the gradation conversion table in the third LUT 60. 2nd L
The correction table of the UT 74 and the dynamic range compression / expansion and gradation conversion table based on the expansion / contraction ratio α in the third LUT 78 are adjusted or reset, and the image displayed on the monitor 18 changes accordingly. If the operator determines that the image is correct (test O
K), an output instruction is issued, and the second LU of the image processing unit 42 is output.
T50 reads the main scan image information from the frame memory 38.

Hereinafter, the image processing unit 4 of the image processing apparatus 14A will be described.
In the same manner as in the image processing unit 42 of the image processing apparatus 14 of the image reproducing apparatus 10 shown in FIG. Processing to generate output image information for image recording, and the image recording device 16
Sent to Note that the above verification need not always be performed. For example, a full auto mode or the like may be set to perform printing without verification. In this case, for example, when the setup unit 44 sets the image processing conditions and the parameter integration unit 48 sets these image processing conditions in the image processing unit 42, the second LUT 50 starts reading the main scan image information. Then, image processing is performed.

Upon receiving the output image information, the image recording device 16 similarly outputs the finished print image P. Similarly, the finished print image P obtained in this manner is free from the occurrence of false contours and the collapse of bright and dark portions, regardless of whether the image is a high-contrast image or a low-contrast image, and the dynamic range is appropriately compressed and expanded. It is a high quality image with a lot of energy. In the image reproducing apparatus 10A of the present embodiment, the setup unit 44 of the condition setting unit 40 uses a pre-scan image having a low pixel density (the number of pixels is smaller than that of the main scan image) obtained by performing the pre-scan. Since the auto setup algorithm can be performed, the processing of the condition setting unit 40 and the image processing of the image signal for display on the monitor 18 can be made quick and simple, and the condition setting unit 40 and the display image processing The configuration of the unit 70 can be simplified, and their circuit scale can be simplified.

Further, in the image reproducing devices 10 and 10A shown in FIGS. 1 and 11, when producing the blurred image information, the digital image signals of the three colors of RGB are used by the image processing devices 14 and 14A, respectively. Although a blur mask signal is generated by performing a filtering process using a filter (FIL 56) of the image processing unit 42, the present invention is not limited to this, and the image reproducing apparatus 10B shown in FIG.
As described above, after converting the RGB three-color digital image signal into a light-dark image signal, a filtering process using a filter (FIL56) may be performed to generate a blur mask signal.

The image reproducing apparatus 10B shown in FIG.
1, the image processing unit 14B and the image processing unit 42B have the first MTX
A second MTX 80 for converting into a bright / dark image signal between the FIL 52 and the FIL 54;
Is composed only of the setup unit 44, and the pre-scan image processing unit 70 is composed only of the LUT 78 for dynamically expanding / compressing and converting the gradation into an image signal suitable for display on the monitor 18. Since they have exactly the same configuration except for the point described above, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the image processing section 42B of the image processing apparatus 14B of the image reproducing apparatus 10B shown in FIG.
The RGB three-color image signals color-corrected by the TX 52 are sent to the subtractor 58, and are also sent to the FIL 56 that generates a blur mask signal for performing image processing such as dynamic range compression / expansion. Instead of being sent, it is converted to a light / dark image signal in advance.
It is sent to the second MTX 80 before the IL 56. The second MTX 80 generates a light and dark image signal of a color original image from the R, G, and B image signals sent from the first MTX 52. As a method of generating a bright / dark image signal, a method of taking one third of the average value of the R, G, and B image signals,
A method of converting a color image signal into a light and dark image signal using the Q rule is exemplified. As a method for obtaining a bright / dark image signal using the YIQ rule, for example, the following equation
A method of calculating only a prescribed Y component from R, G, and B image signals is exemplified. Y = 0.3R + 0.59G + 0.11B

The bright / dark image signal obtained by the second MTX 80 is filtered by the FIL5 in order to generate a blur mask signal.
4 The blur mask signal generated by the FIL 54 is sent to the MUL 56, subjected to dynamic range compression / expansion processing at the expansion / contraction rate α, and then sent to the subtractor 58, where the first M
Each color is subtracted from the color-corrected RGB three-color image signal sent from the TX 52. Hereinafter, similarly, the third LUT
The tone is converted at 60, sent to the image recording device 16, and the finished print image P is output as a visible reproduced image. In the present embodiment, since the blurred image signal by the filtering process is created based on the light and dark image signal converted from the digital image signal of the color original image, the brightness of the reproduced visible image, particularly the brightness of the edge portion of the subject varies. However, since the color reproducibility does not change, it has an appropriate dynamic range, has no crushing of high and low density parts, and has a sharp image, as well as the same unnaturalness as the original color image Images can be played.

Further, in the embodiment shown in FIG. 7, the median filter (MF) 54a and the low-pass filter (L
PF) 54b and these filters 54a and 5
4b, the same digital image signal S _A color-corrected by the MTX 52 is subjected to a filtering process to generate respective blur mask signals 1 and 2 (blurred images 1 and 2), but the present invention is not limited to this. However, similarly to the embodiment shown in FIG.
Filtering processing is performed on the main scan image signal S _A color-corrected in the step (b) to generate a blur mask signal 1 (blurred image 1),
In the LPF 54b, the pre-scanned image signal color-corrected by the MTX 76 of the display image processing unit 70, that is, the pixel density is low, and the thinning-out image signal for the pixel thinned out compared to the main scan image signal S _A is filtered. Thereafter, the blur mask signal 2 (blurred image 2) may be generated by performing interpolation so as to have the same pixel density as the main scan image signal S _A. It should be noted that not only the blurred image by the low-pass filter but also the blurred image by the median filter may be created by interpolating the thinned-out signal of the color original image.
By doing so, the blur mask processing can be performed based on the pre-scan image signal having a small number of pixels, so that a blur mask filter requiring a large-scale circuit configuration is not required, and the device configuration can be simplified.

In order to further reduce the occurrence of false contours, a plurality of median filters having different levels are output as a median filter, or a plurality of median filters having different mask sizes are prepared to generate a blurred image signal. The level of the intermediate value or the mask size may be selected according to the signal distribution of the digital image signal. Also,
Image processing devices 14A and 14A shown in FIGS.
In 4B, the display image processing unit 70 (or only the setup unit 44) for the pre-scan image and the image processing unit 42 (or 42B) for the main scan image are different from each other. Is not limited to
The two image processing units 42 (or 42B) and 70 may be configured the same or exactly the same except for the pixel size (the number of pixels and the capacity) to be processed.

Although the image reproducing method and apparatus of the present invention have been described in detail above, the present invention is not limited to the above-described example, and various improvements and design changes can be made without departing from the gist of the present invention. It goes without saying that it may be performed.

[0092]

As described in detail above, according to the present invention,
False contours do not occur even in color original images with high contrast. Further, according to the present invention, for an image having a wide image density dynamic range, the bright portion and the dark portion are not collapsed, and for an image having a narrow image density dynamic range, image reproduction is performed by making full use of the effective dynamic range. Therefore, a sharp reproduced image can be obtained for any image.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an embodiment of an image reproducing apparatus according to the present invention.

FIG. 2 is a schematic perspective view of an embodiment of an image recording device used in the image reproducing device shown in FIG.

FIG. 3 is a graph showing an example of a density histogram obtained by an image processing device used in the image reproducing device shown in FIG.

FIG. 4 is a conceptual diagram of an embodiment of an adjustment key connected to the image processing apparatus shown in FIG. 1;

5 is an example of a characteristic diagram of a table set in a second LUT of the image processing apparatus shown in FIG. 1, wherein (a) shows a gray balance adjustment table, and (b) shows a brightness correction table. , (C) shows a gradation correction table.

FIG. 6 is an explanatory diagram illustrating an example of a characteristic of a median filter used in the image processing device illustrated in FIG. 1;

FIG. 7 shows a filter (F) of the image processing apparatus shown in FIG.
FIG. 4 is a block diagram illustrating a portion including one embodiment of an IL.

FIG. 8 shows an I used in the image processing apparatus shown in FIG.
FIG. 3 is a circuit diagram illustrating an example of an IR type low-pass filter.

FIG. 9 is a conceptual diagram of an embodiment of a monitor used in the image reproducing apparatus shown in FIG.

FIG. 10 is a diagram showing a flow of a characteristic portion of an example of the image reproducing method according to the present invention.

FIG. 11 is a schematic diagram of another embodiment of the image reproducing apparatus according to the present invention.

FIG. 12 is a schematic diagram of another embodiment of the image reproducing apparatus according to the present invention.

FIG. 13 is a block diagram of another embodiment of the image processing device used in the image reproducing device according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 image reproducing device 12 image reading device 14 image processing device 16 image recording device 18 monitor 20, 96 light source 22 variable aperture 24 color filter plate 26 diffusion box 28 imaging lens 30 CCD sensor 32 amplifier 34 A / D converter 36 LUT ( Lookup table) 38 Frame memory 40 Condition setting unit 42 Image processing unit 44 Setup unit 46 Key input unit 47 Adjustment key 48 Parameter integration unit 50, 74 Second LUT (Lookup table) 52, 76 MTX (Matrix) 54 FIL (Filter) ) 54a median filter 54b LPF (low-pass filter) 54c weighting adder 56 MUL (multiplier) 58,00 adder 60,78 third LUT (lookup table) 62 signal converter 64 D / A converter 66 mau 68 Prescan memory 70 Display image processing unit 80 Second MTX (matrix) 88 Driver 90 Image exposure unit 92 Developing unit 94 AOM (acousto-optic modulator) 98 Polygon mirror 100 Fθ lens 102, 104 Transport roller pair 106 Color developing tank 108 Bleaching / fixing tank 110 Rinse tank A Film Z Photosensitive material P Print

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[Procedure amendment]

[Submission date] August 26, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

However, the photographing conditions of the image photographed on the film are not constant, and there are cases where the difference between light and dark (density) is large, that is, the luminance range of the image, that is, the dynamic range is very wide, such as flash photography or a backlight scene. is there. However, since the maximum density of a photosensitive material such as photographic paper for reproducing an image carried on a film is generally restricted, the photosensitive material is narrower than a dynamic range (luminance range) of a subject image recordable on the film.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

On the other hand, the technique proposed in Japanese Patent Application No. 8-16646 is to produce a blurred image by a median filter on a color original image, and to subtract the difference signal between corresponding pixels of the original image and the blurred image. And subjecting the difference signal to predetermined image processing to reproduce the difference signal as a visible image. This technology has solved the above-mentioned problem of false contours to some extent by using a median filter.However, any of the technologies mentioned here are intended for high-contrast images, and have a dynamic range relative to the original image. the compression process in which the basic principle, low contrast, for example, images, such as during cloudy weather there is a problem that no consideration.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

It is preferable that the blurred image signal is created using a median filter as a smoothing filter that preserves the edge. Alternatively, it is preferable to create the blurred image signal using a median filter and a low-pass filter as the smoothing filter that preserves the edge. Further, it is preferable that the blurred image signal is obtained by weighting and adding a first blurred image signal by the median filter and a second blurred image signal by the low-pass filter.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

It is preferable that the blurred image signal creating means creates the blurred image signal using a median filter as a smoothing filter which preserves the edge. Alternatively, it is preferable that the blurred image signal creating means creates the blurred image signal using a median filter and a low-pass filter as a smoothing filter that preserves the edge. Also, the blurred image signal creating means may convert the blurred image signal into a first blurred image signal by the median filter and a second blurred image signal by the low-pass filter.
Is preferably obtained by weighting and adding the blurred image signal.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

The image reading device 12 used in the present invention comprises:
A device for photoelectrically reading an image photographed on a film A, comprising a light source 20, a variable diaphragm 22 for adjusting the amount of light emitted from the light source 20, and a light source
It has three color filters of R, G and B for converting the image photographed on the film A into three primary colors of RGB by converting into three primary colors of (red), G (green) and B (blue). A color filter plate 24 for rotating and applying an arbitrary color filter to the optical path; and a light filter plate 24 for diffusing light transmitted through the color filters of the color filter plate 24 and uniformly entering the film A in the plane direction. Diffusion box 26 and film A
An imaging lens 28 for forming an image of the reading light transmitted through the CCD sensor 30 on the CCD sensor 30 and an area sensor for photoelectrically reading one image (one frame) of the film A formed by the imaging lens 28. a CCD sensor 3 0, an amplifier 32 for amplifying the RGB3 color image signals read by the CCD sensor 30, the amplified image signal and a / D converter 34 for converting a / D, obtained digital image signals To l
a first LUT (lookup table) 36 for performing og conversion into a density signal.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

In this manner, as shown in FIG. 3, it is assumed that density histograms for three types of luminance Y have been obtained for frames of three different scenes. Here, the image in which the density histogram a indicated by the solid line is obtained is an image having a high frequency of intermediate density and having a general pattern (scene).
Code _{DR o (= Y max o -Y} min o) standard scenes concentration dynamic range (in this case residing in the finished print reproduction region of the light-sensitive material Z of the photographic paper or the like shown by Figure 3, that the standard density range ) concentration than the dynamic range DR _a (a = Y _{max a} -Y _{min a)} is wide fine weather images. On the other hand, the density histogram b indicated by the one-dot chain line indicates that the frequency of the intermediate density is low, the frequency in the high density area and the low density area is high, and the contrast is high.
_{b (= Y max b -Y min} b) has spread beyond the standard density range DR _o, this state when printing high density portion crushed (dark portion) is black, is an image of a low density portion (bright portion) flies white Indicates that On the other hand, the density histogram c indicated by the broken line shows that the image has only a middle density, has very low high and low densities, and has low contrast.
The dynamic range DR _c (= Y _{max c} −
Y _{min c} ) is smaller than the standard range DR _o . For example, it indicates that the image is cloudy.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

Therefore, according to the present invention, in order to stably obtain an appropriate finish regardless of whether the image has a high contrast or an image having a low contrast, the images represented by the density histograms a and b have a dynamic range. , And the image represented by the density histogram c needs to be expanded in the dynamic range. Therefore, in the present invention, the maximum density (Y _max ) and the minimum density (Y _min ) are calculated from the density histogram, the difference between them is calculated, and DR (= Y _max −Y _min ) is calculated in the density dynamic range. Using the density dynamic range DR thus obtained, a dynamic range compression / expansion rate (hereinafter referred to as an expansion / contraction rate) α is calculated according to the following equation. α = 1−DR _o / DR Here, DR _o is an average density dynamic of dozens of scenes that can be reproduced within the print reproduction area of the target photosensitive material, and the average of these dozens of scenes a standard concentration range determined from the difference between the maximum density (Y _{max o)} as the lowest concentration determined from a histogram of concentration (Y _{min o).}
Note that when the scaling factor α > 0, the color original image is compressed, and when the scaling factor α < 0, the color original image is expanded.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

When the frequency of image information on the bright part (highlight) side is high, such as in a snow scene or a backlit scene, the entire dynamic range is increased by strongly compressing the dark part (shadow) side in particular. If compression is effective or if the frequency of image information on the dark side (shadow) is high, such as with flash images, the overall dynamic range can be increased by strongly compressing the bright side (highlight). Compression can be effective in some cases. As described above, preferably, the dynamic range is compressed by adjusting the density of the light and dark portions without changing the gradation of the intermediate density portion so as to provide the same effect as the dodging by the conventional direct exposure. It may be better to process the image information in this way.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0072

[Correction method] Change

[Correction contents]

That is, as shown in FIG. 10, a feature of a preferable mode of image processing in the image reproducing method of the present invention is that a density histogram is prepared in advance from an original image to calculate a density range , and then a dynamic range compression / expansion rate is calculated. α
Is calculated, and a median filter (M
F), the weighted addition of the blurred image 1 generated by the low-pass filter (LPF) and the blurred image 2 generated by the low-pass filter (LPF) are performed, and then, the blurred image is generated by performing compression and expansion using the compression and expansion ratio α calculated in advance. Then, by subtracting the blur image obtained last from the original image, the dynamic range is appropriately compressed / expanded regardless of whether the image is a high-contrast image or a low-contrast image. An object of the present invention is to obtain a sharp, high-quality image with no crushed dark portions.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0075

[Correction method] Change

[Correction contents]

In the image reproducing apparatus 10 shown in FIG.
Prior to image reading (main scanning) for obtaining image information for output, the image reading device 12 performs prescan for coarsely reading an image at a low resolution. The image processing apparatus 14A sets (sets up) various image processing conditions from the image information obtained by the pre-scan, performs image processing on the image information of the main scan in accordance with the image processing conditions, and Output image information for image recording. The image reading method in the pre-scan and the main scan is basically the same, but the only difference is that the resolution of the read image is different. At the time of the pre-scan, the pixels read from the image read by the CCD sensor 30 are thinned out under the control of the timing controller 72 connected to the pre-scan memory 68 of the image processing device 14A, and coarse image information having a low resolution is obtained. Then, image processing is performed in the processing device 10.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0076

[Correction method] Change

[Correction contents]

The image processing apparatus 14 A shown in the figure converts a digital image input from the image reading apparatus 12 into a signal.
A frame memory 38 used as a main scan image memory for performing various image processing including a dynamic range compression / expansion processing, and an image processing condition setting unit 40
And a pre-scan memory 68 and a pre-scan image processing unit (hereinafter, referred to as a pre-scan image processing unit 42).
70 (referred to as a display image processing unit). Further, the pre-scan memory 38 and the frame memory 68 are connected to a timing controller 72 which controls reading of image information for each pixel.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0092

[Correction method] Change

[Correction contents]

[0092]

As described in detail above, according to the present invention,
Even greater color original image contrast, never false contours occur. Further, according to the present invention, for an image having a wide image density dynamic range, the bright portion and the dark portion are not collapsed, and for an image having a narrow image density dynamic range, image reproduction is performed by making full use of the effective dynamic range. Therefore, a sharp reproduced image can be obtained for any image.

[Procedure amendment 13]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

DESCRIPTION OF SYMBOLS 10 Image reproducing device 12 Image reading device 14 Image processing device 16 Image recording device 18 Monitor 20,96 Light source 22 Variable aperture 24 Color filter plate 26 Diffusion box 28 Imaging lens 30 CCD sensor 32 Amplifier 34 A / D Converter 36 LUT (lookup table) 38 Frame memory 40 Condition setting unit 42 Image processing unit 44 Setup unit 46 Key input unit 47 Adjustment key 48 Parameter integration unit 50, 74 Second LUT (Lookup table) 52, 76 MTX (Matrix) ) 54 FIL (filter) 54a Median filter 54b LPF (low-pass filter) 54c Weighted adder 56 MUL (multiplier) 58 Adder 60, 78 Third LUT (lookup table) 62 Signal converter 64 D / A converter 6 Mouse 68 Pre-scan memory 70 Display image processing unit 80 Second MTX (matrix) 88 Driver 90 Image exposure unit 92 Developing unit 94 AOM (acousto-optic modulator) 98 Polygon mirror 100 Fθ lens 102, 104 Transport roller pair 106 Coloring Developing tank 108 Bleaching and fixing tank 110 Rinse tank A Film Z Photosensitive material P Print

Claims (10)

[Claims] 1. An image reproducing method for reproducing a digital image signal representing a color original image as a visible image, wherein the digital image signal is subjected to a filtering process using a smoothing filter that preserves edges, and A blurred image signal representing a blurred image is created, and a dynamic range compression / expansion process of the original image is performed on the digital image signal based on the blurred image signal to obtain a processed image signal. An image reproducing method for reproducing a visible image. 2. A histogram of the original image is created from the digital image signal, a dynamic range of the original image is calculated based on the histogram, and a dynamic range compression according to the digital image signal is performed based on the dynamic range. 2. The image reproducing method according to claim 1, wherein an expansion rate is set, and the dynamic range compression / expansion processing is performed based on the dynamic range compression / expansion rate. 3. The image reproducing method according to claim 1, wherein the dynamic range compression / expansion processing is performed based on a dynamic range compression / expansion rate of the dynamic range compression / expansion processing selected according to a scene of the original image. 4. The image reproducing method according to claim 1, wherein the blurred image signal is created using a median filter as the smoothing filter that preserves the edge. 5. The image reproducing method according to claim 1, wherein the blurred image signal is created using a median filter and a low-pass filter as the smoothing filter storing the edge. 6. The image reproducing method according to claim 5, wherein the blurred image signal is obtained by weighting and adding a first blurred image signal by the median filter and a second blurred image signal by the low-pass filter. 7. The image reproducing method according to claim 6, wherein the second blurred image signal by the low-pass filter is created by interpolating a thinned-out signal of the digital image signal of the original image. 8. The image reproducing method according to claim 5, wherein an IIR filter is used as the low-pass filter. 9. The image reproducing method according to claim 1, wherein said digital image signal is converted into a light / dark signal, and said blurred image signal is created based on said light / dark signal. 10. An image reproducing apparatus for reproducing a digital image signal representing a color original image as a visible image, wherein the digital image signal is passed through a smoothing filter storing edges to represent a blurred image of the original image. A blurred image signal generating means for generating an image signal; and a dynamic range compression / expansion processing means for performing a dynamic range compression / expansion processing of the original image on the digital image signal based on the blurred image signal to obtain a processed image signal An image reproducing apparatus comprising: a reproducing unit that reproduces the processed image signal as a visible image.