JP3494924B2 - Density characteristic correction method and color correction method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention corrects variations in spectral sensitivity characteristics and other characteristics of an image reading device (scanner) in photoelectrically reading an original image, and reproduces an appropriate color according to the original image. The present invention belongs to the technical field of color correction which makes it possible to obtain density correction and proper color reproduction, which are also the basis for performing.

[0002]

2. Description of the Related Art At present, when printing an image photographed on a photographic film (hereinafter referred to as a film) such as a negative film or a reversal film on a photosensitive material (photographic paper), the photosensitive material is exposed by a projection light of the film. Direct exposure (analog exposure) is the mainstream. Similarly, the analog exposure method is also the mainstream for the copying of reflective originals such as printed matter and photographs.

With respect to the former, in recent years, a printing apparatus utilizing digital exposure, that is, an image photographed on a film is photoelectrically read, and after the read image is converted into a digital signal, various image processing is performed. Image data for recording is applied, and a photosensitive material is scanned and exposed by recording light modulated according to the image data to record an image (latent image),
A color digital printer for (finished) prints (photographs) has been put to practical use. Also for the latter, a digital device similar to the above has been put to practical use. Furthermore, recently, in the above-mentioned color digital printer, a device which can be called a compound printer has been put into practical use, which can obtain a copy (print) from a reflection original such as a printed matter or a photograph.

This composite printer is basically a transmission original reading scanner for photoelectrically reading an image photographed on a film with an image sensor, and an image for photoelectrically reading a reflective original such as a printed matter or a photograph with an image sensor. A reflective original reading scanner, an image processing device that performs predetermined image processing on image data read by these scanners or image data supplied from a digital camera or the like, and sets image data for image recording, that is, an exposure condition, and an image. According to the image data output from the processing device, for example, a printer (image recording device) that scans and exposes a photosensitive material by light beam scanning to record a latent image, and a developing process is performed on the photosensitive material exposed by the printer. , And a processor (developing device) for printing a reproduced image.

Since such a composite printer can read an image as digital image data and determine the exposure condition at the time of printing by image data processing, for example, for a negative film image, an image caused by backlighting, stroboscopic photography, or the like is used. It is possible to obtain high-quality prints that could not be obtained by conventional direct exposure by suitably performing processing for correcting jumps and blurs, and processing for sharpness (sharpening). Also,
Image composition, division, character composition, etc. can also be performed by image data processing, and prints that have been freely edited / processed according to the application can also be output. Further, with respect to the image of the reflection original, various kinds of image processing can be performed to obtain a high quality print.

[0006]

By the way, in the transparent original reading scanner and the reflective original reading scanner of the above-mentioned composite printer, the reading light is incident on the original and is reflected by the projection light transmitted through the original (film) and the original. By reading the reflected light with an image sensor such as a CCD sensor, the original image is read photoelectrically. In the case of color originals,
By processing the projected light and reflected light of the document with the red (R), green (G) and blue (B) color filters, or
When the reading light processed by the R, G and B color filters is incident on the original, the image of the original is separated into three primary colors of R, G and B and is read. Here, if the scanners of the same model are used, the same image signal (image data) must be obtained when reading the same document.

However, there are individual differences in the light sources, color filters, image sensors, etc. attached to the scanners, and as a result, the spectral sensitivity characteristics differ from scanner to scanner even within the same model. Therefore, the obtained image signal reflects the spectral sensitivity characteristic of the scanner, and even if a visible image is reproduced using this image signal, the image has a different tint for each scanner. ,
Proper color reproduction according to the original cannot be obtained, that is, a high-quality reproduced image cannot be obtained. There is a similar problem regarding the concentration. That is, even in the case of a monochrome image, since the light source and the image sensor of the scanner have individual differences, the obtained image signal varies from scanner to scanner,
However, there is a problem that it is not always possible to obtain a proper density reproduction according to the original.

A first object of the present invention is to solve the above-mentioned problems of the prior art, and variations in various characteristics of the scanner due to the light source, the optical filter, the image sensor, etc. (reading error resulting therefrom). Another object of the present invention is to provide a density characteristic correction method that also serves as a basis for correcting the above and performing appropriate color reproduction according to the original image. A second object of the present invention is to solve the above-mentioned problems of the prior art, and it is preferable to eliminate variations in the spectral sensitivity of the scanner (reading errors resulting from this) due to the light source, color filter, image sensor, and the like. It is an object of the present invention to provide a color correction method capable of performing correction and obtaining a constant color reproduction.

[0009]

To achieve the above first object, according to the solution to ## density characteristic correction method according to the first aspect of the present invention measures the reference original at a predetermined measuring instrument, at least the image
Obtain measurement results including the signal value and the position information, a first step of storing the measurement results obtained in the storage means, Chez
A second correction parameter is created, and the reference original is read by an image reading apparatus (scanner) to be corrected using this, and the image signal value at a predetermined position in the image area is analyzed to obtain a statistic. An input concentration characteristic correction parameter is calculated from the step, the third step of reading the measurement result stored in the storage means, the statistic obtained in the second step, and the measurement result read in the third step. And a fourth step of

The density characteristic correction method according to the present invention
The input density characteristic correction parameter in
Table (LUT) and the measurement obtained in the first step above.
Minimize the error between the fixed result and the statistic obtained in the second step
Is preferably determined as follows.

Furthermore, the image signal value is preferably a bit resolution higher than the image signal value for normal image formation, and the measured values are RGB based on the status M density, status A density and XYZ colorimetric values. It is preferably either a value or an image signal value obtained by a reference input device (scanner). Moreover, it is preferable that the statistic is either an average value or a median value within a predetermined region. Also, to calculate the lookup table, calculate a polynomial approximation formula,
Preference is given to using the coefficients of the polynomial. In addition, when performing the error minimization calculation, it is preferable to perform weighting that attaches importance to low density. Further, the reference original has a spectrally substantially flat characteristic, and is often an ND filter in the case of a transmissive scanner and a color chart (gray patch or gray chart) in the case of a reflective scanner. Also, the reference original should include a low density portion (density 0.2 or less), and the reference original high density portion (density 2.5 or more for transmission, density 1.5 for reflection). The above should be included.

In order to achieve the above-mentioned second object, the color correction method according to the second aspect of the present invention measures a reference document with a predetermined measuring device, and at least an image signal and its position information.
And a shading correction parameter, which is a first step of storing a measurement result including
Second, a reference data is created, the reference original is read by an image reading device (scanner) to be corrected using the data, and an image signal value at a predetermined position in an image area is analyzed to obtain a statistic.
And the third step of reading the measurement result stored in the storage means, the statistic obtained in the second step, and the input color correction parameter calculated from the measurement result read in the third step. And the fourth step
It is characterized by having.

In the color correction method according to the present invention,
Before reading in the second step above,
For documents with spectrally almost constant reflectance or transmittance
Create an input density correction parameter for the
The above input density correction parameter is
It is preferred to use Further, the color correction according to the present invention
The method is based on the input color correction parameter in the fourth step.
Is the data calculated among candidate parameters that have been obtained in advance?
Select the parameter with the smallest error from the
A correction parameter that minimizes the error generated by the meter.
Calculate the meter, select the parameters and the calculated correction
It is preferable to combine the parameter and.

Further, a one-dimensional lookup table is calculated for only the achromatic portion in the reference original document to absorb the error between the measured value of the reference original document and the correction value due to the parameter obtained here. Good. Further, it is preferable to calculate a polynomial approximation formula and use the coefficient of the polynomial as a parameter for the calculation of the lookup table. Further, it is preferable that the candidate parameter is a secondary matrix coefficient, the calculation correction parameter is a primary matrix coefficient, and the color correction parameter is a secondary matrix. It is preferable to develop a secondary matrix of color correction parameters into a three-dimensional lookup table (by a CPU or the like) and use it as a color correction parameter. It is preferable that the three-dimensional look-up table and the one-dimensional look-up table are combined and used as one three-dimensional look-up table as a color correction parameter.

Furthermore, it is preferable that the image signal value has a higher bit resolution than the image signal value for normal image formation, and the measured values are RGB based on the status M density, status A density, and XYZ colorimetric values. It is preferably either a value or an image signal value obtained by a reference input device (scanner). Moreover, it is preferable that the statistic is either an average value or a median value within a predetermined region. As the reference original, it is preferable to use the reference original that matches the reading target and calculate the input color separation parameter. That is, when reading a negative film, the reference original of the negative film is used, when reading the reversal film, the reference original of the reversal film is used, when reading the photo original, the reference original of the photograph is used, and when reading the printed matter, the reference original of the printed matter is used. Then, it is preferable to calculate each input color separation parameter.

In each of the above aspects, a plurality of reference originals may be used as the reference originals. At this time, the number and use order of the plurality of reference originals are determined in advance, and the measurement results corresponding to the plurality of reference originals are stored in the storage means in the predetermined number and use order, and the predetermined determination is performed. In addition to reading the measurement results from the storage means in the specified use order, the reference document corresponding to the predetermined use order is read by the image reading device to obtain the statistical amount, and the obtained statistical amount And the read corresponding measurement results are sequentially accumulated, and after the statistics and the measurement results for the predetermined number of reference originals are obtained, the input density characteristic correction parameter and the input color are acquired. It is preferable to calculate at least one of the correction parameters. Before using the reference original document, it is preferable to display the plurality of reference original documents to be used and the order of use thereof to notify the outside.

Further, the number and use order of the plurality of reference originals and the measurement results corresponding to the plurality of reference originals are stored in the storage means, and the number and use order of the plurality of reference originals are controlled by the control means. The plurality of reference originals that have been read out and the use order thereof are displayed and notified to the outside, the measurement results are read out from the storage means in the use order, and the corresponding reference originals in the use order are displayed. The statistic amount is obtained by reading with the image reading device, the obtained statistic amount and the read corresponding measurement results are sequentially accumulated, and the statistic amount and the measurement regarding the read number of reference originals are performed. After the result is obtained, it is preferable to calculate at least one of the input density characteristic correction parameter and the input color correction parameter.

Further, the measurement results corresponding to the plurality of reference originals are stored in the storage means in association with the reference originals, the information of the reference originals to be used is obtained, and the corresponding measurement results are obtained from the storage means. And reading the use reference document with the image reading device to obtain the statistic amount, sequentially accumulating the obtained statistic amount and the read corresponding measurement result, and storing the statistic amount and It is preferable to calculate at least one of the input density characteristic correction parameter and the input color correction parameter from the measurement result. Here, the information of the use standard document is
Information is input from the outside by the information input means, and at least one of the input density characteristic correction parameter and the input color correction parameter is calculated based on an instruction to calculate the correction parameter input from the outside by the information input means. Is preferred.

Further, a bar code is attached to the reference original document, and the bar code is read by a bar code reader,
It is preferable that the measurement result corresponding to the read barcode is read from the storage means. Further, at least one of a numeral, a patch density, a pattern, and a bar code is used for a part of the reference original, and information indicating the corresponding measurement result and, if necessary, the input density characteristic correction parameter and Whether or not at least one of the input color correction parameters is calculated is written, and at the same time when the reference original is read by the image reading device, the measurement result information as image information, and whether or not the correction parameter is calculated as necessary. Read the corresponding image information, analyze and judge the read image information, read the corresponding measurement result, and also read the presence or absence of the calculation as necessary, and accumulate the corresponding measurement result when the calculation is not performed. However, when the calculation is performed, at least the input density characteristic correction parameter and the input color correction parameter It is preferable to calculate a person.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The density characteristic correcting method and color correcting method according to the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

First, a density characteristic correction method according to the first aspect of the present invention and a color digital printer using the same will be described with reference to FIGS. 1 to 6B. Figure 1
FIG. 3 is a perspective view showing an appearance of a color digital printer according to an embodiment for carrying out the density characteristic correction method of the first aspect of the present invention. The color digital printer 1 according to the present embodiment is configured in a box shape as a whole, a reflection original reading scanner unit 200 is provided on the upper part of the main body, and a 135 size or 240 size printer is provided next to it. A film scanning unit 10 for copying small transparent originals such as color negatives and slides is detachably mounted. When copying a relatively large transparent document such as a 4 × 5 size slide or proof, or when copying transparent documents such as a plurality of sleeves side by side, the transparent document copy is performed at a predetermined position on the upper surface of the scanner unit 200. The light source device 400 for use is mounted. The details are shown in FIG.

The scanner section 20 provided with the above-mentioned reflection original reading scanner section 200 and transparent original copying light source device 400.
The read image signal at 0 and the read image signal at the film scanning unit 10 together with image signals from other image data supply means (for example, a digital camera, etc.) together with a predetermined image in the image processing apparatus, as described later. It is processed.
In addition, in the lower part of the main body of the color digital printer 1 shown by symbol 2 in FIGS. 1 and 2, a photosensitive material (photographic paper) is printed on the basis of image printing (exposure) information output from the above-mentioned image processing apparatus. A printer unit that performs exposure and a processor unit that develops the exposed printing paper are built in. The color digital printer 1 shown in the present embodiment is an apparatus that uses a photosensitive material as a recording material, which has a heat development step and transfers an image to an image receiving material having an image receiving layer in the presence of an image forming solvent such as water. Thus, the apparatus is capable of printing not only reflective originals such as printed matter and photographs but also transparent originals such as 135 size and 240 size slides, proofs, and color negatives.

First, the film scanning unit 10 will be described below. FIG. 3 shows a block diagram of the film scanning unit 10. The film scanning unit 10 includes an image reading unit 12 that photoelectrically reads an image shot on the film F, and an image processing device 14 that processes image data and operates and controls the entire photo printer. The image processing device 14 inputs an image reading unit 12, a scanner unit 200 described later, and an image data supply source R other than this, input (setting) of various conditions, selection and instruction of processing, color / density correction, and the like. Keyboard 18a and mouse 18b for
An operation system 18 including a display and a display 20 for displaying an image read by the image reading unit 12, various operation instructions, a setting / registration screen of various conditions, and the like are connected.

The image reading section 12 is a section for photoelectrically reading the images photographed on the film F or the like frame by frame.
2, a variable aperture 24, a diffusion box 28 that makes the reading light incident on the film F uniform in the surface direction of the film F,
An imaging lens unit 32, an image sensor 34 having a line CCD sensor corresponding to reading of R (red), G (green) and B (blue) images, and an amplifier (amplifier) 36.
Have and. In addition, in the image reading unit 12, the image is changed in accordance with the type and size of the film such as a new photographic system (Advanced Photo System) or a 135 size negative (or reversal) film, and the form of the film such as strips or slides. A dedicated carrier 30 that can be freely attached to the main body of the reading unit 12 is prepared, and by exchanging the carrier 30, it is possible to handle various films and processes. An image (frame) photographed on a film and used for print production is conveyed to a predetermined reading position by the carrier 30.

As is well known, a magnetic recording medium is formed on the film of the new photographic system, and the cartridge I
Data such as D and film type is recorded, and various data such as shooting date / time, position information of main parts, and developing machine type can be recorded at the time of shooting or developing. Carrier 3 corresponding to the film (cartridge) of the new photographic system
0 is provided with this magnetic information reading means, which reads the magnetic information when the film is conveyed to the reading position,
Various information is sent to the image processing device 14. In such an image reading unit 12, the reading light emitted from the light source 22 and having the light amount adjusted by the variable diaphragm 24 enters the film F positioned at a predetermined reading position by the carrier 30 and is transmitted therethrough. , The projection light carrying the image captured on the film F is obtained.

The carrier 30 is, for example, one of 24 sheets.
It corresponds to a long film F (strips) such as a 35 size film or a cartridge of a new photographic system. As shown schematically in FIG. 4 (a), the film F is placed at a predetermined reading position. While holding the sheet F, the film CCD is conveyed in the sub-scanning direction orthogonal to the extending direction (main scanning direction) of the line CCD sensor of the image sensor 34 while being aligned with the longitudinal direction of the film F. The reading position is sandwiched in the sub-scanning direction. It has a pair of conveying rollers 30a and 30b arranged, and a mask 26 having a slit 26a extending in the main scanning direction and corresponding to the reading position, which regulates the projection light of the film F into a predetermined slit shape. .

The reading light is incident on the film F while being held at the reading position by the carrier 30 and being conveyed in the sub-scanning direction. As a result, the film F is two-dimensionally slit-scanned by the slit 26a extending in the main scanning direction, and the image of each frame (original image) captured on the film F is read. The projection light of the film F is transmitted by the imaging lens unit 32 to the image sensor 3
An image is formed on the light receiving surface of No. 4.

As shown in FIG. 4B, the image sensor 34 is a line CCD sensor 3 for reading an R image.
Line CCD sensor 34G for reading 4R, G images,
And a so-called 3-line color CCD sensor having a line CCD sensor 34B for reading the B image, and each line CCD sensor extends in the main scanning direction as described above. The projection light of the film F is separated into three primary colors of R, G and B by the image sensor 34 and photoelectrically read. The output signal of the image sensor 34 is amplified by the amplifier 36 and sent to the image processing device 14.

Next, returning to FIG. 2, the scanner section 200 will be described. The scanner unit 200 is covered with a box-shaped casing, a rectangular opening is provided in the center of the upper surface, and a transparent platen glass 202 is fitted therein. The platen glass 202 has a function as a flat original placing table, and a reflective original or a transparent original having a flat image recorded thereon is placed on the platen glass 202. Further, a pressing cover 204 that can be opened and closed is provided on the platen glass 202.

A halogen lamp 40 as a light source is provided in the transparent original scanning section 232 of the transparent original copying light source device 400.
2 and a light source unit 408 for a transparent original provided with a reflector 404. The transparent original light source unit 408 irradiates the platen glass 202 in the width direction (from the front side to the rear side in FIG. 2), and the main scanning direction when the transparent original is placed on the platen glass 202. Becomes In the transparent original copying light source device 400, the transparent original scanning unit 232 moves in the sub-scanning direction on the platen glass 202, and the transparent original placed on the platen glass 202 is two-dimensionally moved by the transparent original light source unit 408. Scan. An operation / display panel (not shown) is provided on the front side of the upper surface of the casing of the scanner unit 200, and various instruction of functions and an operation state in the apparatus are displayed.

The scanner section 200 is provided with a scanning section 208. The scanning unit 208 is controlled by the controller 209. The scanning unit 208 extends in the width direction of the original image together with the light source unit 210 for the reflection original, which includes a halogen lamp and a reflector extending in the width direction (main scanning direction) of the original image, and the light source unit 210 for the reflection original. A first carriage 214 incorporating the ejected first mirror 212, a second carriage 220 incorporating a second mirror 216 and a third mirror 218,
A diaphragm 222, a filter group 224 composed of four elements including a color adjustment filter and an ND filter, and a lens 2 for image formation
And a fixed unit 228 constituted by 26.

In the first carriage 214, the light from the light source unit 210 for the reflected original is applied to the original placed on the surface of the platen glass 202, and the reflected light (light of the hanging optical axis) is applied to the first carriage 214. It has a role of deflecting 90 ° by the mirror 212 and guiding it to the second mirror 216 of the second carriage 220. Further, the first mirror 212 of the first carriage 214 is configured to guide the transmitted light, which is emitted from the light source unit 408 for transparent original and has passed through the transparent original, to the second mirror 216. In the second carriage 220, the reflecting surface of the second mirror 216 is the first mirror 212.
When the light is received from the first mirror 212, it is 90 ° at the second mirror 216.
It is deflected, and further is deflected by 90 ° by the third mirror 218.

The light finally made parallel to the surface of the platen glass 202 by the third mirror 218 passes through the fixed unit 228 and reaches the light receiving portion of the line CCD sensor 230. The line CC of the present embodiment
The light receiving section of the D sensor 230 is composed of three lines that independently detect the amount of received light for each color (RGB), as in the case described above with reference to FIG. In this fixed unit 228, the ND of the diaphragm 222 and the filter group 224
The light amount is adjusted by the filter, and the filter group 22
Each color balance is adjusted by the color adjustment filter No. 4. Further, the lens 226 forms a document image on the light receiving surface of the line CCD sensor 230. An IR cut film corresponding to the IR cut filter is deposited on the lens surface of the color adjustment filter.

The first carriage 214 and the second carriage 220 reciprocate in the sub-scanning direction below the platen glass 202 along the document surface. At this time, in order to always keep the optical path length from the document reflection (or transmission) position to the light receiving portion of the line CCD sensor 230, the second carriage 220 is the same as the first carriage 214 at a conveyance speed of 1/2. It is designed to move in the direction. This first
One reciprocating operation of the carriage 214 and the second carriage 220 is scanning for one image (image reading in the forward path),
As a result, the original image on the platen glass 202 can be read.

The transparent original scanning unit 232 performs the same operation as that of the first carriage 214 by the driving force of a light source unit driving unit (not shown). That is, when scanning the transparent original, the transparent original scanning unit 232 operates in synchronization with the first carriage 214. At this time, the reflective original light source unit 210 of the first carriage 214 is turned off, and the halogen lamp of the transparent original light source unit in the transparent original scanning unit 232 is turned on, so that the transparent original is reflected by the first mirror 212. Images can be obtained. The subsequent operation is the same as that of the reflection original.

In the present invention, the scanner is not limited to the one based on the slit scanning as described above, but may be one that uses surface exposure for reading the entire surface of one frame image at a time. In this case, for example, area CC
Using the D sensor, the R, G, and B color filter insertion means are provided between the light source and the film F, and the color CCD is inserted to read the image with the area CCD sensor.
The R, G, and B color filters are sequentially performed, and the image photographed on the film is decomposed into three primary colors and sequentially performed. The same applies to the reflection original reading scanner. The transparent original (film) image reading result by the film scanning unit 10 and the reflection and transparent original image reading results by the scanner unit 200 described above are sent to the image processing device 14 described below.

FIG. 5 shows a schematic internal configuration of the image processing apparatus 14. As shown in FIG. 3, the image processing device 14 is
It is composed of an image processing unit 38 and a data conversion unit 40. The image processing unit 38 performs A / D (analog / digital) conversion of the input read image signal.
D conversion unit, film reading scanner (image reading unit 12)
A pre-processing unit 42 including a data conversion unit for performing data conversion such as negative-positive conversion and dynamic range adjustment of the image signal of the film read by the device, and a Log conversion unit for performing logarithmic conversion amplification, and R, G , B frame memories 4
4, a processing unit 50 that performs various kinds of image processing described later, and a condition setting unit 5 that controls various processing conditions by the processing unit 50.
Have two.

The condition setting section 52 selects the image processing to be performed, sets the image processing conditions in the processing section 50 using the image data input from the frame memory 44, and supplies the image processing conditions to the processing section 50. The processing unit 50 has a density correction unit 50A, which is a characteristic part of the present invention, and an image processing unit 50B that performs various types of image processing that have been conventionally performed. Note that FIG. 5 shows only a part related to image processing in the image processing apparatus 14, and the image processing apparatus 14 is not limited to this, and controls the entire color digital printer 1 including the image processing apparatus 14 and the like. A management CPU, a memory for storing information necessary for the operation of the color digital printer 1 and the like are arranged, and the operation system 18 and the display 2 are arranged.
0 is connected to each part via this CPU or the like (CPU bus).

In the image processing device 14, the measurement result (including the measurement position and the measurement value) of the reference original by the reference measuring device 56 such as a spectrophotometer which is one of the characteristic parts of the present invention.
And a storage device 58 for reading out the measurement result and supplying it to the density correction unit 50A of the image processing device 14.
Are connected. Here, the storage device 58 may be a memory such as a built-in memory or an external memory or a hard disk device, or a magnetic recording medium such as a floppy disk (FD) or M.
Magneto-optical recording medium such as O, optical disc (CD, CD-R)
It may be a combination of a storage medium such as an optical recording medium and a driving device therefor. Here, for ease of handling, it is preferable to store it in a storage medium and read it from the driving device to the density correction unit 50A as needed.

The normal operation of the color digital printer according to the present embodiment configured as described above is as follows. That is, the image data supplied from the image reading unit 12, the scanner unit 200, or another image data supply source R is processed by the A / D (analog) in the preprocessing unit 42 of the image processing unit 38 in the image processing apparatus 14. / Digital) conversion, Log conversion, DC offset correction, shading correction, and the like, and then image processing as described later is performed. Next, the image data processed in this manner is converted into image data corresponding to print creation (image recording) in the printer described above in the data conversion unit 40, image data corresponding to image display on the display 20, or both. To be done.

Here, in the color digital printer according to the present embodiment, the image reproduced on the print in the printer unit and the image displayed on the display 20 can be made more identical, for the reason that In the image processing unit 38, the same processing is performed on the same image data regardless of the output to the printer unit and the display 20 described above, and the data conversion unit 40 converts the same with the conversion parameters corresponding to the printer unit and the display 20, respectively. Treatment is preferred.

In the image processing unit 38, as described above, the R, G, and B image signals supplied from the image reading unit 12, the scanner unit 200, or another image data supply unit R are preprocessed. After that, first, in the density correction unit 50A, correction (density correction) such as dark correction and shading correction for obtaining a predetermined image signal is performed on an image having a constant density. Next, the image signal is subjected to predetermined image processing in the image processing unit 50B, and then converted into image data for output corresponding to image recording in the printer unit or image data corresponding to image display on the display 20. , To the printer unit or the display 20. The printer section exposes a photosensitive material (printing paper) according to the supplied image data to record a latent image, and the exposed photosensitive material is subjected to predetermined processing by the processor section and output as a print. Display 20
Then, the screen display is performed based on the supplied image data.

There are no particular restrictions on the image processing performed by the image processing unit 50B described above. For example, color balance adjustment, gradation adjustment, density adjustment, saturation adjustment, electronic scaling processing, dodging processing ( Density dynamic range compression / expansion),
Various types of image processing performed by a known image processing apparatus, such as sharpness processing, are exemplified. Each of these processes may be performed by a known means using a process using an LUT, a matrix calculator, a filter, an adder, or the like, or an averaging process or an interpolation calculation performed by appropriately combining these.

Next, the density characteristic correction method according to the present invention will be described.
The color digital printer according to the present embodiment will be described with reference to the characteristic operation of the scanner, which is a density characteristic correction parameter acquisition operation of the scanner. In the following description, the density characteristic correction method according to the present invention will be described by taking the reflective original reading scanner unit 200 as a representative example, but the present invention is not limited to this, and the transparent original scanner 12 and a large transparent original. It goes without saying that the invention can be applied to a document reading scanner (scanner unit 200 including the light source device 400).

An outline of the operation is shown in the flowcharts of FIGS. 6 (a) and 6 (b). As shown in FIG. 6A, first, the reference document is measured by the reference measuring device (56: see FIG. 5) (step 301), and the measurement result (including the measured value and its position information) is stored in the storage device ( 58: see FIG. 5)
(Step 302). Next, FIG. 6 (b)
As shown in FIG. 3, the image reading apparatus to be corrected, here, the scanner unit 200 in FIG. 1, performs the shading correction and then reads the reference reflection original (steps 401 and 402). And based on this measurement result,
A statistical value such as an average value or an intermediate value of the image signal values in the predetermined image area is obtained (step 403). Around this time, the measurement result (including the reference measurement value and its position information) of the reference document by the reference measuring device 56 previously stored in the storage device 58 is read (step 404) and this and the statistics obtained in step 403. The input density characteristic correction parameter is calculated from the value (step 405).

The details of the operation shown in each step will be described below. First, at the time of measurement in step 301 shown in FIG. 6A, a reference document for preparing an input density characteristic correction parameter is prepared, and the image is measured by a measuring instrument 56 such as a spectrophotometer that can obtain standard data. To measure. This measured value is preferably the spectral transmittance of the reference document (spectral reflectance in the case of a reflective document). For example, it is preferable that the density of the color negative film is the status M density, and the density of the color reversal film, the color positive film, the color print, etc. is the status A density.
Further, the measured values may be RGB values based on XYZ colorimetric values. These measured values are preferably read by the aforementioned reference input device.

Here, the reference original has spectrally almost flat characteristics, that is, ND filters of various densities in the case of a transmissive scanner, and achromatic patches of various densities in the case of a reflective scanner. The chart can be illustrated. Here, the reference document has, for example, a density of 0.
It is preferable to include a low concentration part of 2 or less. Further, it is preferable to include a high density portion having a density of 2.5 or more for a transparent original and 1.5 or more for a reflective original. The reference document may be a reference document having the same density on the entire surface of the document or a reference document having a plurality of density portions having different densities. Further, the density characteristic correction method of the present invention may be performed using one reference original, but a plurality of reference originals may be used. In particular, when a reference original having the same density on the entire surface is used, it is preferable to use a plurality of reference originals. Here, when using a plurality of reference originals, it is necessary to associate the reference originals with the measurement values (including the position information) stored in the storage device 58. , Which will be described later.

In step 302 shown in FIG. 6A, the above-mentioned measured values are stored in the storage device 58. As the storage device 58, as described above, for example, a known storage medium such as a flexible disk (floppy disk) or an IC card and its drive device can be used. The information stored in the storage device 58 is position information of each point (which may be determined in advance) on the reference document and an image signal (measurement value) corresponding thereto. The above-mentioned position information is designated, for example, as a position in the area where the above-mentioned patch is formed in the chart which is the reference document.

The input density characteristic correction parameter of the scanner or the like to be corrected is calculated using the above-mentioned reference measurement value. In the scanner unit 200, as shown in FIG. 6B, after the shading correction is performed by the normal method (step 401), the above-mentioned reference original is read (step 402), and the read data is A / D. It is converted into a digital image signal by the converter and sent to the density correction unit 50A. At this time, position information on the reference document is also acquired.

The density correction section 50A analyzes the image signal of the predetermined area of the reference original document from the supplied image signal of the reference original document, and calculates the statistical amount thereof (step 403). In the illustrated example, the measuring device 56 is further preferable.
And a difference caused by the optical system of the scanner 12, specifically, a difference caused by flare or the like is set as a statistic. The statistic is not particularly limited, and an average value, a median value, an integrated value, etc. are preferably exemplified.

The density correction unit 50A further includes a storage device 58.
Then, the above-mentioned reference measurement value and its position information are read (step 404). Then, the input density characteristic correction parameter of the scanner 12 is calculated using the acquired reference measurement value and the previously calculated statistic (step 405). In addition,
At this time, the measured values are associated with each other using the above-mentioned position information.

The method of calculating the above-mentioned input density characteristic correction parameter will be described in detail below. The method of calculating the input concentration characteristic correction parameter using the reference measurement value and the statistic is not particularly limited, and various known methods can be used according to the calculated statistic. The following method is illustrated as a preferable method.

The density correction unit 50A compares the above-mentioned reference measurement value and the statistic, and uses the difference as an input density characteristic correction parameter. The input density characteristic correction parameter is exemplified by one having a primary matrix. For example, using the luminance (Y), Y is calculated from an arithmetic expression such as (1) Y = (R + G + B) / 3 (2) Y = 0.11R + 0.59G + 0.30B, and the statistical amount based on this is calculated. An error minimization or error maximum likelihood calculation is performed from the reference measurement value to create a correction parameter, which is converted into an LUT.
Here, when the above-described error minimization or error maximum likelihood calculation is performed, good results can be obtained by performing weighting that places importance on low density.

For example, the least squares method can be applied to the above-mentioned error minimization operation. The input density characteristic correction parameter is a 3 × 4 matrix representing the correction amount for each color, and an LUT for calculating the density correction amount using this matrix.
Created as. That is, for example, R ′ = LUT _R (f _R (R, G, B)) between the input R and the output R ′, where f _R (R, G, B) = β ₀ R + β ₁ G + β ₂ B + β _The relationship of ₃ is established. The same relationship holds for the inputs G and B and the outputs G ′ and B ′.

Further, it is preferable that the above-mentioned input density characteristic correction parameter is created according to the type of the original document, and the read signal is corrected using the input density characteristic correction parameter corresponding to the original document to be read. For example, in the case of the image reading unit 12 that reads the film F as shown in FIG. 3, it is preferable to create input density characteristic correction parameters corresponding to each of the negative film and the reversal film. Further, in the case of the scanner section 200 for a reflective original and a transparent original as shown in FIG. 2, it is necessary to create input density characteristic correction parameters corresponding to each of a photograph and a printed matter or a transparent original (film). preferable.

The input density characteristic correction parameter does not have to be created (updated) each time the image is read or each time the color digital printer 1 is started, and it is set at the time of shipment from the factory or at the image reading unit 12 or the scanner unit 200. It may be created only when a component that may change the spectral sensitivity (color separation) characteristic is changed or adjusted. Specifically, at the time of factory shipment, the reading light source is changed, the color filter arranged in the reading optical path of the scanner is changed, and the image sensor 34 (each line C
When the color separation filter attached to the CD sensor) is changed, a new input density characteristic correction parameter is created.

In the present invention, the spectral sensitivity characteristic of the image reading section 12 or the scanner section 200 is estimated using one reference original, and the input density characteristic correction parameter is created based on this to estimate the spectral sensitivity of the scanner. Can be appropriately corrected to enable stable reproduction of high-quality images with constant color reproduction, and input density characteristic correction parameters can be created for various originals.

In digital image reading, A / D conversion is performed with a high gradation resolution of 12 bits or the like, for example, Lo.
Although image data corresponding to image processing of 8 bits or the like is often converted by g conversion, the above-described calculation of the input density characteristic correction parameter and correction of the image signal using the same are performed by the image processing unit 50B. Image signal with higher gradation resolution than the image data corresponding to image processing in
It is preferable that the conversion is performed (including the converted image data) in terms of accuracy and the like. The input density characteristic correction method according to the first aspect of the present invention is not limited to being applied to the composite printing apparatus as described above, but can be widely applied to all image processing apparatuses including an image reading apparatus (scanner). is there. The input density characteristic correction method according to the first aspect of the present invention is basically configured as described above.

Next, the color correction method according to the second aspect of the present invention will be described in detail mainly with reference to FIGS. 7 to 9C. The color correction method of the second aspect of the present invention is carried out by using the image processing device 15 shown in FIG. 7 instead of the image processing device 14 of the color digital printer 1 shown in FIGS. The image processing apparatus 15 shown in FIG. 7 has the same configuration as the image processing apparatus 14 shown in FIG. 5, except that the configuration of the processing unit 51 of the image processing unit 39 is different from the configuration of the processing unit 50 of the image processing unit 38. Therefore, the description of the similar function and action of the both is omitted, and the same reference numerals are given to the same constituent elements in the both, and the detailed description thereof will be omitted.

FIG. 7 shows an outline of the internal structure of the image processing apparatus 15. As shown in FIG. 7, the image processing device 15 includes an image processing unit 39 and a data conversion unit 40. The image processing unit 39 includes the pre-processing unit 42 described above and the R, G, and B frame memories 44 described above.
And a condition setting unit 52 that controls various processing conditions by the processing unit 51, which performs various image processes described below.
Have. The condition setting unit 52 described above selects the image processing to be performed, sets the image processing condition in the processing unit 51 using the image data input from the frame memory 44, and supplies the image processing condition to the processing unit 51. The processing unit 51 includes a density correction unit 51A, a color correction unit 51B, and an image processing unit 50B that performs various types of image processing that have been conventionally performed, which are characteristic features of the present invention.

In the image processing unit 39, the R, G, and B image signals supplied by the preprocessing unit 42 are preprocessed as described above, and then stored in the frame memory 44 of each color. Next, the processing unit 51 is read from each frame memory 44 by R,
The G and B preprocessed image signals are read. Processing unit 51
In the above, first, the density correction unit 51A performs correction (density correction) for obtaining an image signal of a predetermined density, such as dark correction and shading correction. Next, in the color correction unit 51B, the density-corrected image signal is subjected to color correction to be described later by the color correction method of the second aspect of the present invention. Thereafter, the color-corrected image signal is subjected to predetermined image processing by the image processing unit 50B,
Output image data corresponding to image recording in the printer unit and image data corresponding to image display on the display 20 are output to the printer unit and display 20.

Here, the color correction method of the second aspect of the present invention will be described with reference to the color digital printer 1 shown in FIGS. 1 to 4B and FIG. The input color correction parameter acquisition operation will be described. In the following description, the color correction method according to the present invention will be described using the reflective original reading scanner unit 200 as a representative example, but the present invention is not limited to this, and the transparent original scanner 12 or a large transparent original. Scanner for reading (light source device 40
It goes without saying that it is also applicable to the scanner unit 200) having 0.

An outline of the operation is shown in the flowcharts of FIGS. 8 (a) and 8 (b). First, as shown in FIG. 8A, the reference measuring device 56 measures the reference document (step 501), and the measurement result is stored in the storage device 58 as described above.
(Step 502). Next, FIG. 8 (b)
As shown in FIG. 3, the image reading apparatus to be corrected, here, the scanner unit 200 in FIG. 1, performs the shading correction and then reads the reference reflection original (steps 601 and 202). And based on this measurement result,
A statistical value such as an average value or an intermediate value of image signal values in a predetermined image area is obtained (step 603). Before and after this, the measurement result of the reference document by the reference measuring device 56 previously stored in the storage device 58 (reference measurement value and its position information)
(Step 604), and this and step 603
An input color correction parameter is calculated from the statistical value (statistical calculation value) obtained in (step 605).

Details of the operation shown in each of the above steps will be described below. First, at the time of measurement in step 501 shown in FIG. 8A, a reference document for preparing input color correction parameters is prepared, and the image thereof is measured by a measuring device 56 such as a spectrophotometer that can obtain standard data. taking measurement. This measured value is preferably the spectral transmittance of the reference document (spectral reflectance in the case of a reflective document). For example, it is preferable that the density of the color negative film is the status M density, and the density of the color reversal film, the color positive film, the color print, etc. is the status A density. Further, the measured values may be RGB values based on XYZ colorimetric values.
These measurements are preferably read by the aforementioned reference input device, as described above.

Here, the reference original may be any one as long as it can measure the spectral sensitivity of the scanner. For example, patches of various hues, or achromatic patches of various saturations and various densities are formed. A reference document, for example, a Macbeth chart, an ANSI color target, and the like are exemplified. It should be noted that the reference original is a reference negative original when reading a negative film, a reference reversal original when reading a reversal film, a reference photo original when reading a photo original, and a reference print original when reading a print original. It is preferable to use a reference document.

Further, as the reference measuring device 56, a reference input device as described above, for example, a drum scanner in which a color separation filter is strictly controlled can be cited. In step 502 shown in FIG. 8A, the above-mentioned measured value is stored in the storage device 58. As the storage device 58,
As described above, for example, a known storage medium such as a flexible disk (floppy disk) or an IC card and its driving device can be used. The information stored in the storage device 58 is position information of each point (which may be determined in advance) on the reference document and an image signal (measurement value) corresponding thereto. The above-mentioned position information is designated as a position in the area where the above-mentioned patch is formed in the chart which is the reference document, for example.

In the following, the color correction parameters of the scanner to be corrected are calculated using this reference measurement value. Here, as described above, a case where the reflection original is read by the scanner unit 200 will be described with reference to FIG. In the scanner unit 200, after shading correction is performed by a normal method (step 601), the reference document is read (step 602), and the read data is converted into a digital image signal by an A / D converter. Further, the density correction unit 51
The density is corrected in A and is supplied to the color correction unit 51B as an image signal. At this time, position information on the reference document is also acquired.

Next, the color correction section 51B analyzes the image signal of the predetermined area of the reference original document from the supplied image signal of the reference original document, and calculates the statistical amount thereof (step 603).
In the illustrated example, as a further preferable aspect, a difference caused by the measuring device 56 and the optical system of the scanner unit 200,
Specifically, the statistic is obtained by correcting the difference caused by flare or the like. The statistic is not particularly limited, and an average value, a median value, an integrated value, etc. are preferably exemplified. The color correction unit 51B is
Further, the above-mentioned reference measurement value and its position information are read from the storage device 58 (step 604). Then, the input color correction parameter of the scanner unit 200 is calculated using the acquired reference measurement value and the statistic value calculated previously (step 605). At this time, the measured values are associated with each other using the position information.

The method of calculating the input color correction parameter in step 605 will be described in detail below. The method of calculating the input color correction parameter using the reference measurement value and the statistic is not particularly limited, and various known methods can be used according to the calculated statistic, but in the present invention, the following are preferred methods. Is exemplified. In the illustrated apparatus, a plurality of input color correction parameter candidates (hereinafter, referred to as candidate parameters) are prepared in advance corresponding to the spectral sensitivity characteristics of the scanner section 200. The color correction unit 51B is
An image signal (hereinafter referred to as a read estimated value) estimated to be obtained by the scanner unit 200 performing the color correction and then reading the reference document is calculated for each of the candidate parameters.
Calculate the statistics.

Then, as described above, the statistic calculated from the image signal obtained by actually reading the reference document by the scanner section 200 and the statistic calculated from the above-mentioned read estimated value are compared to obtain the best result. The candidate parameter for which a statistical amount with a small error is obtained is used as a candidate for the input color correction parameter of the scanner unit 200. Next, a correction parameter that minimizes the error generated from the selected candidate parameters is calculated, and the selected color correction parameter candidate and the calculated error correction parameter are combined to obtain one parameter. calculate.

The input color correction parameter is a combination of one or more selected from a three-dimensional LUT (look-up table) formed by expanding a primary matrix, a secondary matrix and a secondary matrix, and will be described later. In addition to the above parameters, one-dimensional L
Parameters with UT, 3D LUT and 1D LU
A three-dimensional LUT or the like obtained by combining T and T is exemplified.
For example, if the color correction parameter candidate is a quadratic matrix coefficient and the error correction parameter is a primary matrix coefficient, the color correction parameter obtained by combining these is a quadratic matrix. Then, the color correction parameters of the secondary matrix are developed into a three-dimensional LUT (lookup table) by the CPU and used as the color correction parameters.

9 (a), 9 (b) and 9 (c) show an example of the internal structure of the color correction section 51B having the above-mentioned function. As shown in FIG. 9A, the color correction unit 51B basically has a 3 × 10 matrix 51B that represents a secondary matrix as an example of a plurality of prepared candidate parameters.
−1 and a 3 × 4 matrix 51 that represents a primary matrix as an example of a parameter for correcting an error that occurs when a candidate parameter selected from these is used.
B-2 and LUT 51B-3 for calculating the color correction amount when using both of these parameters. Further, as shown in FIG. 9B, the 3 × 10 matrix 51 described above is used.
It is also possible to combine B-1 and the 3 × 4 matrix 51B-2 into a three-dimensional LUT 51B-4.

Further, the three-dimensional LUT 51B-4 and the LUT 51B-3 for calculating the correction amount are collectively shown in FIG.
It is also possible to use a new three-dimensional LUT 51B-5 as shown in FIG. First, the above-mentioned three-dimensional L shown in FIG.
To show the contents of UT51B-5 as an example, input R and output R '
And R ′ = LUT _R (f _R (R, G, B)) where f _R (R, G, B) = α ₀ R + α ₁ G + α ₂ B + α ₃ R
² + α ₄ G ² + α ₅ B ² + α ₆ RG + α ₇ GB + α ₈ B
The relationship of R + α ₉ is established. The same relationship holds for the inputs G and B and the outputs G ′ and B ′.

Further, in addition to the correction by the color correction parameter, in order to absorb the error between the measured value of the original and the correction value by the correction parameter calculated above for only the achromatic portion in the reference original, 1 It is also possible to increase the accuracy of correction by calculating the dimension LUT. The LUT calculation means used here is exemplified by one that calculates a polynomial approximation formula and uses polynomial coefficients as parameters. The above-mentioned correction for only the achromatic part is
It may be performed before the color correction or after the color correction. It should be noted that the above-described one-dimensional LUT for correction only for the achromatic portion and the above-described three-dimensional LUT for color correction
It is also possible to combine (51B-5) and form one three-dimensional LUT.

Such input color correction parameters are created corresponding to the document type, and the color correction section 51B corrects the image signal using the input color correction parameters corresponding to the type of document to be read. Is preferred. For example,
Image reading unit 1 for reading the film F as shown in FIG.
In the case of 2, it is preferable to create input color correction parameters corresponding to each of the negative film and the reversal film, and more preferably to create for each film maker, grade and film type. Further, in the case of the scanner unit 200 for a reflective original and a transparent original as shown in FIG. 2, input color correction parameters corresponding to a photograph and a printed matter, a transparent original (film), or the like, more preferably photographic paper (photograph). It is preferable to create input color correction parameters according to the type of photosensitive material, printing factory, and the like.

The input color correction parameter does not have to be created (updated) each time the image is read or each time the color digital printer 1 is started up. The factory setting, the spectral sensitivity of the image reading unit 12 or the scanner unit 200 ( A new input color correction parameter may be created only when a component whose color separation characteristic may change (replacement) or adjustment is performed. Specifically, when the reading light source is changed, the color filter arranged in the reading optical path of the scanner is changed, or the color separation filter attached to the image sensor (each line CCD sensor) is changed at the time of factory shipment. , Create new input color correction parameters. In the above description, as a preferable mode, the input color correction parameter is set to the density correction unit 51A.
However, the present invention is not limited to this, and for example, the color correction unit 51B is arranged before (upstream side) the density correction unit 51A. You may.

In the present invention, the spectral sensitivity characteristic of the image reading unit 12 or the scanner unit 200 is estimated using one reference original, and the input color correction parameter is created based on this to estimate the spectral sensitivity of the scanner. It is possible to appropriately correct the variations to enable stable reproduction of high-quality images with constant color reproduction, and to create input color correction parameters for various originals. Further, in digital image reading, A / D conversion is often performed with a high gradation resolution of 12 bits or the like, and for example, log conversion is often performed to image data corresponding to image processing of 8 bits or the like. The above-described calculation of the input color correction parameter and the correction of the image signal using the input color correction parameter are performed by the image signal having the gradation resolution higher than that of the image data corresponding to the image processing in the image processing unit 50B (log-converted image data Included)
It is preferable in terms of accuracy and the like. In the present invention, Lo
Image data that has not been g-converted is also included as an image signal. Therefore, the color correction unit 51B is arranged on the upstream side of the Log conversion unit, and the above processing is performed using image data that is not Log-converted. Good.

Further, in the present invention, the density correction section 51A shown in FIG. 7 is replaced with the density correction section 50A shown in FIG. 5, and the density characteristic correction method of the first aspect of the present invention and the second method of the present invention are replaced. Both the color correction method of the aspect may be performed. At this time, it is preferable for proper color reproduction that the density correction unit 50A performs the density characteristic correction according to the present invention and then the color correction unit 51B performs the color correction according to the present invention. Needless to say, it is not limited to this. In this case, a standard document such as a Macbeth chart or an ANSI color target may be used as the standard document, but in terms of correction accuracy, the most suitable standard document should be selected. preferable. Further, the color correction method according to the second aspect of the present invention is not limited to being applied to the composite printing apparatus as described above, but can be widely applied to all image processing apparatuses including an image reading apparatus (scanner). The color correction method according to the second aspect of the present invention is basically configured as described above.

In the above-mentioned example, the correction parameter such as the input density characteristic correction parameter or the input color correction parameter or both of them is created using one reference original, but the present invention is not limited to this. The correction parameters may be created using a plurality of reference originals. In this case, it is necessary to associate each reference document with the measurement result (including the measurement value and the measurement position information). The following methods can be given as the associating method used in the density characteristic method and the color correcting method of the present invention.

First, the first method is applied when the number of reference originals to be used and the order of use are predetermined. Here, first, the measuring device 5 for each reference document is used.
6 are stored in the storage device 58 in a predetermined number and in the order of use (step 30 in FIG. 6A).
1, 302 or steps 501, 50 in FIG.
2). Next, the measurement results are read out from the storage device 58 in a predetermined use order (step 404 in FIG. 6B or step 604 in FIG. 8B), and the corresponding reference originals are scanned in the predetermined use order. (For example, the scanner unit 200) reads the statistic (see FIG. 6).
(B) Steps 401 to 403 or FIG. 8 (b) Steps 601 to 603). The statistics obtained in this way and the corresponding measurement results read are sequentially accumulated. After the statistic and the measurement result regarding the predetermined number of reference originals are obtained, the correction parameter is calculated (FIG. 6 (b) step 405 or FIG. 8 (b) step 605).

The second method is applied in the same manner as the above-mentioned first method when the order of use of the reference originals, the number of the reference originals, and the corresponding measurement results are predetermined. In this method, first, similarly to the first method, the number and use order of a plurality of reference originals to be used and the measurement results corresponding to the plurality of reference originals are stored in the storage device 58. A plurality of reference originals used in the display 20 and the order of use thereof are displayed, that is, which reference original is used, and the outside is notified to the operator. After this,
Similar to the first method described above, the measurement result is read out and the statistical amount is calculated, the measurement result and the statistical amount are accumulated, and the expected number of post-accumulation correction parameters are calculated.

In the third method, the number of reference originals to be used is previously determined to be one and a plurality of use orders are prepared, or the use reference originals whose use number and use order are predetermined are set. Applies when multiple sets are prepared. In this method, the number and the order of use of a plurality of reference originals to be used and the measurement results corresponding to the plurality of reference originals are stored in the storage device 58 in advance. The control device reads the use order of the plurality of reference originals or the number and use order of the plurality of reference originals. Thereafter, similar to the second method, a plurality of reference originals used in the display 20 and the order of use thereof are displayed, that is, which reference original is used, and the outside is notified, that is, the operator. To do. Then, the correction parameter is calculated in the same manner as the second method.

The fourth method is applied when the relationship between a plurality of reference originals that may be used and the corresponding measurement results is stored. In this method, a plurality of reference originals and the measurement results corresponding thereto are associated and stored in the storage device 58. Get information on the reference manuscript used,
For example, the information of the usage reference document is automatically set by the control means inside the apparatus, or is input from the outside by the information input means (by the operator), and the measurement result corresponding to the usage reference document is read from the storage device 58. On the other hand, similarly to the above-mentioned method, the usage reference document is read by the scanner to obtain the statistics. The obtained statistics and the corresponding measurement results read are sequentially accumulated. After accumulating a predetermined number, or externally, for example, after an operator inputs an instruction to calculate the correction parameter by the information input means, the correction parameter is calculated from the accumulated statistics and the measurement result.

When a plurality of reference originals are used, the reference originals and the measurement results are associated or associated with each other by attaching a bar code to the reference original and reading the bar code with a bar code reader. The measurement result corresponding to the code may be read from the storage device 58. In addition, at least one of a number, a patch density, a pattern, and a bar code is used to write information indicating the corresponding measurement result in a part of the reference document, and at the same time when the reference document is read by the scanner, it is converted into image information. You may read the information of a measurement result, analyze the image information (information of a measurement result) read here, judge it, and read a corresponding measurement result.

Further, at least one of a number, a patch density, a pattern, and a bar code is written on a part of the reference original document together with the information indicating the corresponding measurement result and the presence / absence of calculation of the correction parameter. Simultaneously with the reading of the reference document, the measurement result information as the image information and the presence / absence of the calculation of the correction parameter are read, the read image information is analyzed and judged, and the corresponding measurement result and the presence / absence of the calculation of the correction parameter are read out. It is preferable to accumulate the corresponding measurement results when the correction parameter is not calculated and to calculate the correction parameter when the correction parameter is calculated.

Although the density characteristic correction method of the first aspect and the color correction method of the second aspect of the present invention have been described in detail above with reference to various examples, the present invention is limited to these examples. Of course, various improvements and changes may be made without departing from the scope of the present invention.

[0087]

As described above in detail, according to the density characteristic correction method of the first aspect of the present invention, in photoelectric image reading, variations in various characteristics of the scanner are corrected,
It is possible to perform density correction, which is a basis for performing proper color reproduction according to an original image, and it is possible to stably reproduce a high-quality image in a color digital printer or the like. Further, as described in detail, according to the color correction method of the second aspect of the present invention, it is possible to suitably correct the variation in the spectral sensitivity of the scanner in photoelectric image reading, and to use a color digital printer or the like. In, it is possible to stably reproduce a high-quality image in which the color is properly reproduced.

Furthermore, when the density characteristic correction method of the first aspect and the color correction method of the second aspect of the present invention are carried out simultaneously, variations in various characteristics of the scanner are corrected in photoelectric image reading, Since it is possible to perform density characteristic correction that is the basis for performing proper color reproduction according to the original image, and it is also possible to suitably correct the variation in the spectral sensitivity of the scanner.
It is possible to stably reproduce a high-quality image in which colors and densities are properly reproduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a color digital printer according to an embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of an embodiment of a scanner unit in FIG.

FIG. 3 is a block diagram of an embodiment of the film scanning unit shown in FIGS. 1 and 2.

4A is a conceptual diagram of an embodiment of a carrier set in the film scanning unit shown in FIG.
(B) is a conceptual diagram of an embodiment of an image sensor that is also set in the film scanning unit.

5 is a block diagram of an embodiment of an image processing apparatus in the film scanning unit shown in FIG.

6A and 6B are flowcharts showing an outline of an example of an input density characteristic correction parameter calculation operation in the scanner according to the present embodiment.

7 is a block diagram of another embodiment of the image processing apparatus in the film scanning unit shown in FIG.

8A and 8B are flowcharts showing an outline of an example of an input color correction parameter calculation operation in a scanner according to another embodiment of the present invention.

9 (a), (b) and (c) are respectively,
FIG. 8 is a diagram showing an internal configuration of an embodiment of a color correction unit in the image processing apparatus shown in FIG. 7.

[Explanation of symbols]

1 color digital printer 10 Film scanning unit 12 Image reading unit (scanner) 14, 15 Image processing device 18 Operation system 20 display 30 career 32 Imaging lens unit 34 image sensor 36 amplifier 38,39 Image processing unit 40 data conversion unit 42 Pretreatment section 44 frame memory 50,51 Processing unit 50A, 51A density correction unit 50B image processing unit 51B color correction unit 52 Condition setting section 56 Measuring instrument 58 storage 200 Scanner section 400 Light source device for transparent original copy

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H04N 1/60 H04N 1/46 A (56) Reference JP-A-8-111784 (JP, A) JP-A-7-222013 ( JP, A) JP 9-130622 (JP, A) JP 8-279919 (JP, A) JP 9-289589 (JP, A) JP 6-105131 (JP, A) JP JP 9-6956 (JP, A) JP 9-27917 (JP, A) JP 9-83704 (JP, A) JP 9-9086 (JP, A) JP 9-139855 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (24)

(57) [Claims] 1. A measured reference original at a predetermined measuring instrument, less
Both obtain the measurement result including the image signal value and its position information,
The first step of storing the obtained measurement result in the storage means and the shading correction parameter are created, and the reference document is read by the image reading device to be corrected using this, and a predetermined value in the image area is read. A second step of analyzing the image signal value at the position to obtain a statistic, and a third step of reading the measurement result stored in the storage means.
And a statistic amount obtained in the second step, and a fourth step of calculating an input density characteristic correction parameter from the measurement result read in the third step. . 2. The input density characteristic correction parameter is a look-up table (LUT), and is determined so as to minimize the error between the measurement result obtained in the first step and the statistic obtained in the second step. The density characteristic correction method according to claim 1, wherein the density characteristic correction method is performed. 3. The density characteristic correction method according to claim 1, wherein a plurality of reference originals are used as the reference originals. 4. A predetermined number and order of use of said plurality of reference original, stores the plurality of measurements corresponding to the reference document in the storage means at this predetermined number and order of use, the The statistical results were obtained by reading the measurement results from the storage means in the predetermined order of use and reading the corresponding reference original in the predetermined order of use by the image reading device. The input density characteristic correction parameter is calculated after the statistics and the read corresponding measurement results are sequentially accumulated, and the statistics and the measurement results for the predetermined number of reference originals are obtained. The density characteristic correction method according to claim 3 . 5. A Before using the reference original, density characteristic correction method according to claim 4 to notify the outside by displaying a plurality of reference original and its use order used. 6. stores the measurement results corresponding to the number and order of use and the plurality of reference original of the plurality of reference original in the storage means, the number and order of using the plurality of reference document by the control means The plurality of reference originals that have been read out and the use order thereof are displayed and notified to the outside, the measurement results are read out from the storage means in the use order, and the corresponding reference originals in the use order are displayed. The statistic amount is obtained by reading with the image reading device, the obtained statistic amount and the read corresponding measurement results are sequentially accumulated, and the statistic amount and the measurement regarding the read number of reference originals are performed. 4. The density characteristic correction method according to claim 3 , wherein the input density characteristic correction parameter is calculated after the result is obtained. 7. The measurement results corresponding to the plurality of reference originals are stored in the storage means in association with the reference originals, the information of the reference originals to be used is obtained, and the corresponding measurement results are obtained from the storage means. And reading the use reference document with the image reading device to obtain the statistic amount, sequentially accumulating the obtained statistic amount and the read corresponding measurement result, and storing the statistic amount and The density characteristic correction method according to claim 3 , wherein the input density characteristic correction parameter is calculated from the measurement result. 8. The information of the used reference original is inputted by the information input means from the outside, the input density characteristic correction parameters inputted from the outside by the information input means, the calculation of the input density characteristic correction parameter The density characteristic correction method according to claim 7, which is calculated based on an instruction. 9. A bar code is attached to the reference document,
The density characteristic correction method according to claim 1 , wherein the barcode is read by a barcode reader, and the measurement result corresponding to the read barcode is read from the storage means. . 10. A portion of the reference document, numbers, patch density, using at least one of the patterns and barcodes in advance by writing information indicating the corresponding the measurement results, the value determined by the image reading apparatus At the same time as reading the original, reading the measurement result information as image information,
10. The method according to claim 1 , wherein the read image information is analyzed and judged, and the corresponding measurement result is read out.
Density characteristic correcting method Rekani described. 11. Use of at least one of a numeral, a patch density, a pattern and a bar code on a part of the reference original document together with information indicating the corresponding measurement result and whether or not the input density characteristic correction parameter is calculated. Write it down,
Simultaneously with the reading of the reference document by the image reading device, the measurement result information as the image information and the presence or absence of the calculation of the input density characteristic correction parameter are read, and the read image information is analyzed and judged to determine the correspondence. measurement and reading the presence or absence of the calculation, in the case without the calculation accumulates the corresponding measurement results in the case of there the calculation calculates the input density characteristic correction parameter according
Item 10. The density characteristic correction method according to any one of items 1 to 3 and 7 to 9 . 12. A measuring a reference document in a predetermined measuring instrument, small
At least the measurement result including the image signal value and its position information
Obtained, a first step of storing the measurement results obtained in the memory means, to create a shading correction parameter read by the image reading apparatus of the correction target <br/> the reference document by using this, the image area A second step of analyzing the image signal value at a predetermined position to obtain a statistic, and a third step of reading out the measurement result stored in the storage means.
And a statistic obtained in the second step, and a fourth step of calculating an input color correction parameter from the measurement result read in the third step. 13. An input density correction parameter for an original having a spectrally almost constant reflectance or transmittance is created before reading by the image reading device in the second step, and the second step is performed. 2. The input density correction parameter is used when reading in 1.
2. The color correction method described in 2 . 14. In the calculation of the input color correction parameter in the fourth step, a parameter having the smallest error is selected from the candidate parameters obtained in advance, and the error generated from the selected parameter is minimized. 13. A method for calculating such a correction parameter, and combining the selected parameter and the calculated correction parameter.
Or the color correction method described in 13 . 15. As the reference document, claim 1 using the reference document of the same type as the type of document to be read subject
The color correction method according to any one of 2 to 14 . 16. The color correction method according to claim 12, wherein a plurality of reference originals are used as the reference originals. 17. The number and use order of the plurality of reference originals are determined in advance, and the measurement results corresponding to the plurality of reference originals are stored in the storage unit in the predetermined number and use order. The statistical results were obtained by reading the measurement results from the storage means in the predetermined use order and reading the corresponding reference originals in the predetermined use order by the image reading device. The statistic and the read corresponding measurement result are sequentially accumulated, and after the statistic and the measurement result for the predetermined number of reference originals are obtained, the input color correction parameter is calculated. The color correction method according to claim 16 . 18. The color correction method according to claim 17, wherein before the reference original is used, the plurality of reference originals to be used and the order of use thereof are displayed and notified to the outside. 19. The number and use order of the plurality of reference originals and the measurement results corresponding to the plurality of reference originals are stored in the storage means, and the control means determines the number and use order of the plurality of reference originals. The plurality of reference originals that have been read out and the use order thereof are displayed and notified to the outside, the measurement results are read out from the storage means in the use order, and the corresponding reference originals in the use order are displayed. Obtain the statistic by reading with the image reading device,
The obtained statistic and the read corresponding measurement result are sequentially accumulated, and after the statistic and the measurement result regarding the read number of reference originals are obtained, the input color correction parameter The color correction method according to claim 16, wherein 20. Measurement results corresponding to the plurality of reference originals are stored in the storage means in association with the reference originals, information of the reference originals to be used is obtained, and corresponding measurement results are obtained from the storage means. And reading the use reference document with the image reading device to obtain the statistic amount, sequentially accumulating the obtained statistic amount and the read corresponding measurement result, and storing the statistic amount and from the measurement results, wherein for calculating the input color correction parameter
Item 17. The color correction method according to Item 16 . 21. The information of the use reference original document is externally input by an information input unit, and the input color correction parameter is externally input by the information input unit.
The color correction method according to claim 20, which is calculated based on an instruction to calculate the input color correction parameter. 22. A bar code is attached to the reference original document, the bar code is read by a bar code reader, and the measurement result corresponding to the read bar code is read out from the storage means . 21 Izu
The color correction method of Rekani described. 23. At least one of a numeral, a patch density, a pattern, and a bar code is used to write information indicating the corresponding measurement result on a part of the reference original, and the reference by the image reading device is written. At the same time as reading the original, reading the measurement result information as image information,
The read image information is analyzed and judged, and the corresponding measurement result is read out.
2. The color correction method according to any one of 2 . 24. The presence or absence of calculation of the input color correction parameter is written in a part of the reference document by using at least one of a number, a patch density, a pattern and a bar code together with information indicating the corresponding measurement result. At the same time as the reading of the reference document by the image reading device, the presence or absence of calculation of the measurement result information and the input color correction parameter as image information is read, and the read image information is analyzed and judged. The correspondence measurement result and the presence / absence of the calculation are read out, the correspondence measurement result is accumulated when the calculation is not performed, and the input color correction parameter is calculated when the calculation is performed.
23. The color correction method according to any one of 22 to 22 .