JP3342623B2 - Image data conversion method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data conversion method and apparatus for recording an image by digitally processing image data obtained from a photographic original such as a color negative film.

[0002]

2. Description of the Related Art An image signal control amount is obtained based on an image signal obtained by imaging a reflection original such as a print photograph or a photographic film, and a reproduced image is reproduced on a color photosensitive material or other recording medium based on the image signal control amount. In a conventional digital printer for recording a color, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-157758, a reference density point is determined for each color component based on a highlight density and a shadow density in an original image.
A gradation conversion curve is set so that these density values become a predetermined signal level.

Japanese Patent Application Laid-Open No. Hei 6-242521 discloses that a screen is divided into a plurality of regions, and a maximum reference value and a minimum reference value are determined from a maximum value and a minimum value of each color in each region.
It is disclosed that the maximum reference value of each color is reproduced as white and the minimum reference value is reproduced as black.

Japanese Patent Laid-Open Publication No. Hei 6-178113 discloses a histogram accumulating means for creating a histogram from image data and accumulating and storing the histogram in a storage means corresponding to the type of recording medium. It is disclosed that a gradation table is obtained from data to create a conversion table for image reproduction. It also discloses that the histogram is corrected in a direction that eliminates the bias in frequency, or that a related image is selected from a series of image groups and used as an image representative value of the reproduction conversion characteristic.

Regarding the setting of the gradation of a digital image, there are many known methods for storing and using a reference gradation characteristic. For example, JP-A-60-37878 and JP-A-60-21
No. 6350, JP-A-62-111569, JP-A-62-111571, JP-A-63-4257.
No. 5 publication. Japanese Patent Application Laid-Open No. 60-37878 discloses a method in which a plurality of standard tone curves are stored, and a standard tone curve most similar to a tone curve created from a document is selected. JP-A-60-216350, JP-A-62-111569, JP-A-62-1115
No. 71 discloses a method of correcting a stored reference gradation conversion curve using data of a specific point. JP-A-63-425
No. 75 discloses a method using a third gradation conversion curve obtained by synthesizing a standard gradation conversion curve and a gradation conversion curve determined from a document.

[0006]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 2-157 is disclosed.
As disclosed in Japanese Patent No. 758, almost all of the conventional digital image recording methods control a highlight portion and a shadow portion of an original image to be a highlight portion and a shadow portion of a reproduced image. For this reason, inconvenience occurs when the highlight portion and the shadow portion are not white or black, respectively. In the case where the screen is divided into a plurality of regions and the maximum reference value and the minimum reference value are determined from the maximum value and the minimum value of each color in each region, as in JP-A-6-242521 described above, When the screen is divided into a plurality of regions, the maximum reference value and the minimum reference value may be erroneously changed. In addition, Japanese Unexamined Patent Application Publication No.
The method of creating a histogram from image data and accumulating the histogram in storage means corresponding to the type of recording medium as in JP-B-178113 discloses a method in which the exposure amount at the time of photographing is almost uniform and suitable, as in a reversal film. Is significant. On the other hand, in a recording medium such as a negative film in which characteristics such as three-color density balance and gradation are different depending on a photographing exposure amount, the shape of the histogram differs depending on the exposure amount even for the same subject. It is difficult to accurately obtain the required film characteristics from the accumulation of the histogram.

[0007] Further, the three-color density balance of a negative film differs depending on the film type and the change in film characteristics due to the aging of the film. In particular, since the film type is designed so that an optimum three-color density balance can be obtained by combining it with the target recording material, if this combination is different, an appropriate three-color density balance cannot be obtained and the reproduction quality is poor. Will be enough. In addition, in the setting of the three-color density balance according to the above-described conventional method, since the reproduction condition is determined for each image using the image data, color variation occurs between the recorded images.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has an appropriate three-color density balance even when the film type is different from under to overexposure density and from highlight to shadow in an image. It is an object of the present invention to provide an image data conversion method and apparatus capable of obtaining a recorded image and obtaining a high-quality recorded image in consideration of the gradation characteristics of an original image .

[0009]

According to another aspect of the present invention, there is provided an image data conversion method for converting a common gradation characteristic of a film type to which a color film belongs from a standard gradation characteristic to a reference gradation characteristic. look, which was to convert the image data on the basis of the conversion condition, the conversion of the image data, the first relating to tone characteristic of the predetermined reference
A conversion table is created from the characteristics and the second characteristics relating to the gradation characteristics stored for each film type, and the conversion table is used .

According to a second aspect of the present invention, there is provided an image data conversion method, wherein a conversion condition for converting a gradation characteristic common to a series of film images included in a color film into a reference gradation characteristic is determined, and an image is converted based on the conversion condition. The data is converted , and the conversion of the image data is performed in a predetermined manner.
A first characteristic relating to a reference gradation characteristic, and the color file;
The gradation characteristics stored for a series of image data
A conversion table is created from the second characteristic and the conversion table.
Bull is used .

It is preferable that the first and second characteristics are a color balance between respective colors of a film image formed of a neutral color or a subject color approximate to the neutral color. The first and second characteristics include film characteristic curve data representing the relationship between the film image density and subject brightness, color balance between colors obtained from image data of a large number of film images for each film type, and color. The color balance between each color obtained from the image data of a series of many film images including the film image of the film may be used. Furthermore,
The first characteristic may be determined based on the recording material, and the second characteristic may be determined from the image data of the film image.

Further , the image data conversion apparatus of the present invention has a first storage means for recording a first characteristic relating to a predetermined reference image characteristic, and a second storage means for storing a second characteristic relating to an image characteristic obtained from the film. (2) storage means, and conversion condition creation means for creating conversion conditions for converting image data of the color film to be printed into image data of the first property from the first and second characteristics of the two storage means,
A conversion unit for storing the conversion conditions and converting the image data of the color film to be printed into the first characteristic.

[0013]

FIG. 1 is a functional block diagram showing a digital printer embodying the present invention. This digital printer is roughly divided into image signal input means 10 and
A tone balance conversion lookup table memory (LUT) 11 as a tone balance conversion means, an image recording basic amount calculation means 12, a recording image data conversion LUT 13,
And an image recording unit 14. Also, each LUT1
Conversion table creation means 15, 16 are connected to 1, 13, and the conversion tables are written in each LUT 11, 13.

The image signal input means 10 comprises a known film scanner, and reads an image of a negative film and converts it into an image signal. Image signal input means 10
Is capable of performing a main scan and a pre-scan. In the pre-scan, an image of a negative film is read out as thousands of image data. Note that the number of image data in the pre-scan is not limited to several thousands, and it is sufficient that several hundreds to several tens of thousands of image data can be read in response to a request for improving print quality or reducing processing time. In the main scan, an image of a negative film is read out as hundreds of thousands to several millions of image data. In FIG. 1, the flow of image data of the main scan is indicated by a dotted line,
The flow of other prescan image data and the like is indicated by solid lines. Image data obtained by the main scan from the image signal input means 10 is sent to the gradation balance conversion LUT 11, where it is converted into image data corresponding to the reference film type, as will be described in detail later. The pre-scanned image data from the image signal input means 10 is supplied to an image data selecting means 20 and an image recording basic amount calculating means
Sent to In addition to separately performing the pre-scan and the main scan in this way, as described in detail later, the image data of the main scan is combined, and the number of pixels is reduced from several hundred pixels to tens of thousands of pixels. This may be used as prescan image data.

Tone balance conversion table creating means 15
Creates a gradation balance conversion table for converting the gradation balance, and writes this in the LUT 11. For this purpose, a first characteristic storage unit 17 and a second characteristic storage unit 18 are connected to the conversion table creation unit 15.

The first characteristic storage means 17 is a means for recording characteristic data of a reference film. The three-color density balance of a color negative film differs depending on the film density. This is because the R, G, and B characteristic curves of color negative films (the relationship between the obtained color density and the amount of exposure to the film) are not parallel (this characteristic is called gradation balance), that is, the R, G, and B levels. Due to different tones. This gradation balance differs depending on the film type. However, the most desirable gradation balance is determined directly from the characteristics of the recording material and the negative film type (reference film or average value of a plurality of non-existent film types) recommended as a combination thereof and the characteristics of the recording material. This is defined as a reference film characteristic (first characteristic). First
The characteristic storage means 17 stores this reference film characteristic. This reference film characteristic may be an actual film characteristic as described above or an ideal film characteristic that does not exist. When an existing reference film characteristic is used, it may be created while collecting image data, or may be separately created and stored.

The second characteristic storage means 18 stores, for each type of color negative film to be printed, a film characteristic (second film characteristic) obtained from a large number of images in the same manner as the reference film characteristic.
Characteristics).

FIG. 2 shows an example of the first characteristic, and FIG.
An example of the characteristic is shown. 2 and 3, the horizontal axis represents the G density and the vertical axis represents the R density. These first and second 2
From the two characteristics, as shown in FIG. 4, the horizontal axis represents the R density of the second characteristic, and the vertical axis represents the R density of the first characteristic, and the R density of FIG. 2 and the R density of FIG. It is possible to create a gradation balance conversion table indicating the relationship between the R density of the first characteristic and the R density of the second characteristic from the density. By using this gradation balance conversion table, it is possible to convert the R density image data of the film type A to be printed into the R density image data of the reference film type. Similarly, a table representing the relationship between the first characteristic and the second characteristic with the G concentration on the horizontal axis and the B concentration on the vertical axis is created.
From the two tables, a gradation balance conversion table representing the relationship between the B density of the first characteristic and the B density of the second characteristic is created. These gradation balance conversion tables are written in the gradation balance conversion LUT 11. By converting image data using this gradation balance conversion table, any film type or image can be converted into image data having an appropriate color balance from highlight to shadow. Therefore, since the color balance is appropriate, a gray subject is reproduced as gray.

It is preferable that the second characteristic is obtained from a large number of image data. Therefore, as shown in FIG. 1, an image data storage unit 19 is connected to the second characteristic storage unit 18. The pre-scanned image data from the image signal input unit 10 is input to the image data storage unit 19 via the image data selection unit 20.
The image data storage means 19 includes the original image type identification means 2.
1 is connected, and a film type signal of a negative film to be printed is input. In addition,
The first characteristic and the second characteristic need only be able to create a table representing the relationship between the first characteristic and the second characteristic as shown in FIG. 4, and are limited to the characteristics shown in FIGS. Not something.

The original image type identifying means 21 is a means for identifying the type of the original image. A bar code reader for determining the film type and a magnetic reading device for reading magnetic information correspond to this, and these bar codes and magnetic information recorded on the negative film are read to determine the film type and the like. The original image type identification means 21 includes, in addition to the discrimination of these film types, identification of a negative film and a positive film,
Other means for identifying the storage medium may be included.
When an original image belongs to a series of multiple images, such as a photographic film, the series of original images can be regarded as the same original image type.

The image data accumulating means 19 accumulates and accumulates the R density, the B density with respect to the G density of the image data and the number of image data in the corresponding storage area based on the film type signal. In the present embodiment, as described above, the G density is used as a classification criterion for image data. Then, it is determined which level of the G density value of the image data corresponds to, for example, the level classified at the 0.01 interval or the 0.1 interval, and the R density and the B density are accumulated at the corresponding level. At the same time, the number of accumulated data is counted and stored. Then, for a large number of image data, the accumulated accumulated image data is divided by the number of accumulated data to obtain an average value. Using this average value, a characteristic curve of the second characteristic is created as shown in FIG. Instead of obtaining the average value, a multidimensional function expression by multiple regression analysis or the like may be obtained. When the average value is used, the average value is a complicated curve connecting a large number of points plotted. Therefore, it is preferable to correct each point by performing a well-known smoothing process. The method of storing image data is described in detail in, for example, Japanese Patent Application Laid-Open No. 3-53235. Further, the average value of a large number of stored data is constant and becomes gray or a color close to gray. In the case of a color close to gray, the deviation from gray can be converted to gray by adding a certain correction value.

The image data selection means 20 selects image data according to a predetermined selection criterion, and sends the selected image data to the image data storage means 19. As the selection criterion, the average value of the image data of the corresponding film type stored in the image data storage unit 19 based on the film type signal from the original image type identification unit 21 is used. Then, based on the average value, only image data within a predetermined range is selected. Instead of the average value, a value determined by a statistical method such as the least squares method may be used. The image data selected in this way has an image density of a subject color in a substantially gray or a certain range close to gray. For example, by using a selection criterion such as not storing high-saturation image data, not storing image data having a maximum reference density or more and a minimum reference density or less, the image data storage means 19 can accurately store image data. Will be able to

Recorded image data conversion table creation means 16
Is based on the pre-scan image data converted by the gradation balance conversion LUT 11, the basic image recording amount from the basic image recording amount calculating unit 12, and the recording condition parameter from the recording condition storage unit 22. A table is created and written in the LUT 13. The recording condition storage unit 22 sets parameters for obtaining an appropriate image according to the difference between the image signal input unit 10 and the image recording unit 14 and the characteristics of the recording material.

The image recording basic amount calculating means 12 is based on the prescanned image data from the image signal input means 10 and has a basic image recording amount Dmi (i is one of R, G and B).
Ask for. The image recording basic amount Dmi is a value obtained from the image density of the original image for each original image. Based on the prescanned image data, a simple average value in each area such as a full screen area, a specific area, and a selected area is calculated. , Which are selectively used. In addition to this, as the image recording basic amount Dmi, an average value of weighted addition with respect to a pixel position, an average value of selected pixels, an average value of weighted addition, and the like are used.

The basic image recording amount Dmi is disclosed in
6569, JP-A-61-223731, JP-A-2-90140, JP-A-3-53235, JP-A-5-289207 and the like. You can ask. Furthermore,
The image recording basic amount Dmi is a weighted average value between a maximum value (or highlight portion density) and a minimum value (or shadow portion density), and a weighted average value obtained by multiplying each pixel by a weight (for example, each of the density histograms). Values that characterize the image of the original image, such as a weighted average value obtained by multiplying a class by a weight), a value corresponding to a specific frequency of the cumulative density histogram, or a value corresponding to the selected frequency, particularly described in JP-A-5-100328. A value that characterizes a certain main subject density or a value that has a correlation with the main subject density can be used as the image recording basic amount Dmi. Further, a density control value may be used. In this case, JP-A-51-138435,
JP-A-53-145621, JP-A-54-281
No. 31, JP-A-59-164547, and the like, and can be determined by a known method.

More specifically, the recording image data conversion table creating means 16 calculates, for example,
It creates a record image data conversion table for converting the scanned image data Dij of the image signal input unit 10 to the recording image data E _ij for each pixel. Then, the recording image data conversion table is written in the recording image data conversion LUT 13.

[0027]

[Number 1] _{logE ij = -ai · Dij + Dmi} + ΔDC + bi However, D _ij: scan image data of each color (density value of each pixel of the original image) Dmi: recording the fundamental volume .DELTA.DC: Manual density, color correction values a _i, b _i: Coefficient (determined by recording material, image recording means, etc.) i: Any one of R, G, B j: Pixel number

[0028] FIG. 5 shows an example of a conversion table created on the basis of the equation 1, takes the image signal D _Rj of R on the horizontal axis, is obtained taking the recorded image data logErj the vertical axis. Similarly, similar conversion tables are created for the other G and B, and are written in the LUT 13. In the present invention, since the three-color balance is adjusted to the reference film type by the gradation balance conversion LUT 11, the recorded image data conversion table determined for the reference film type can be used as it is.

FIG. 5 shows an example in which the main part density DpO is used as the basic image recording amount Dmi. DpO and EpR respectively represent data necessary for obtaining the main part density of the original image and the proper main part density of the recorded image. The data EpR for the main part density of the recorded image is used to obtain the proper density. ,
For example, the conversion table is modified as shown by a two-dot chain line in FIG. The density of the prescanned image data corrected by the gradation balance conversion LUT 11 is used as the main portion density of the original image. The method of determining the main part area is described in, for example, JP-A-52-156624 and JP-A-2-28.
As described in JP-A-7531 and JP-A-4-346332, a method of extracting a main subject (human face) from a film image can be used. Further, the data EpR for the main part density of the recorded image is obtained in advance,
This is recorded in the recording condition storage means 22. Then, the data for the density of the main part of the recorded image is input to the conversion table creating means 16.

Recording image data conversion table creating means 16
Then, the conversion table is changed so as to be indicated by a two-dot chain line in FIG. 5 so that the main part density DpO of the original image matches the main part density data EpR of the recorded image. What is indicated by the two-dot chain line in FIG. 5 is one in which only the vicinity of the main part concentration is corrected with emphasis. In addition, as shown in FIG. 6, the change in the density of the highlight portion may be reduced and the image reproduction of the shadow portion may be corrected as not important. Further, practically, it is preferable that the conversion table for correcting the data for the main part density be corrected so as to have a smooth curve. in this way,
If the data EpR for the main part density of the recorded image does not match the main part density DpO of the original image, the conversion table may be changed according to the image contents, if necessary, based on the reference recorded image data conversion table shown by the solid line in FIGS. Is corrected. The image content is determined using a known method. For example, a large number of scenes are classified for each pattern in advance by a statistical method, and the image content is determined by determining to which pattern the prescanned image data belongs.

As shown in FIG. 1, the image recording means 14 converts the recording image data from the recording image data conversion LUT 13 into an image recording control amount and records the image. Note that the recording image data conversion LUT 13 may directly convert the image recording control amount from the main scan image data. As the image recording means 14, a known video printer that scans and exposes each of the yellow, magenta, and cyan photosensitive layers of a silver halide photographic color photosensitive material (color paper) with a light beam is used.

As shown in FIG. 7, the image data identification means 19 is also connected to the first characteristic storage means 30, and the first characteristic is stored in the same manner as the method for obtaining the second characteristic shown in FIG. You may ask. In this case, the reference film type is determined and identified by the original image type identification means 21. Further, the first characteristic and the second characteristic may use a film characteristic curve representing a relationship between a film image density and a subject luminance. In FIG. 7, the same units as those in FIG. 1 are denoted by the same reference numerals.

Further, the recording image data conversion table creating means 16 may include a process for media conversion. By this media conversion processing, problems that occur when a hard copy is created from a film image, such as lightness reproduction, hue correction, compression of chroma reproduction, and enhancement of a color or highlight image, are performed. Further, the media conversion processing may be provided as another means in the conversion processing system 40. In addition, edge enhancement, pseudo contour removal, noise removal, and calibration for machine difference and fluctuation are often used in the image processing apparatus. However, these known image processing methods may be added.

In the above embodiment, the pre-scanned image data is stored for each film type, and the second characteristic is obtained by using the average value of the pre-scanned image data. The image may be prescanned at once, and the second characteristic may be obtained using the prescanned image data. A series of film images in this case indicates an image of one negative film or a similar image within one film. The extraction of the similar image is determined by statistical analysis of the image data, identification of the imaging light source, and magnetic information stored in advance.

The pre-scan and the main scan may use different photometric systems or the same photometric system. When the same photometric system is used, the main scan may be performed after the prescan, or the main scan may be performed to perform pixel density conversion to obtain prescan image data. Alternatively, as described above, the main scan may be performed after prescanning one file image at a time.

Further, at the time of main scanning of a plurality of images, prescanned image data may be obtained in the same manner. Specifically, as shown in FIG. 8, a main scan is performed by the image signal input unit 34, and pre-scan image data is obtained by pixel density conversion of the main scan image data. Further, the main scan image data is stored in the image memory 35 for a plurality of images. The second characteristic is obtained by the second characteristic storage means 18 based on the plurality of prescanned image data and stored. Tone balance conversion table creation means 1
In step 5, a gradation balance conversion condition is obtained, and a gradation balance conversion table is created. Thereafter, the main scan image data is read out from the image memory 35 and the gradation balance conversion L
Data conversion is performed by the UT 11.

The density in the present invention includes not only an optical density but also a converted value corresponding to chromaticity lightness, a photometric output value of an original image, a dot area ratio, and the like. Also, an anti-log value of the density can be applied. In the above embodiment, the color negative film has been described. However, the present invention can also be applied to a positive film.

The image recording section may be constituted by an exposure means for controlling a large number of pixels spread in a line or area, such as a liquid crystal or a CRT, in addition to a light beam. Further, the recording material is not limited to a color photosensitive material, and may be, for example, a thermal printing material, a thermal printing method using a sublimation type or a heat melting type ink ribbon, an inkjet printing method, a toner transfer printing method, and the like. Good.

In the above embodiment, the first conversion condition (a = f (x)) is created by the gradation balance conversion table creating means 15 from the first characteristic and the second characteristic. The recording image data conversion table creating means 16 creates the second conversion condition (y = g (a)) in consideration of the basic image recording amount, the recording condition, and the like. And these first
And the second conversion condition is written in each of the LUTs 11 and 13, the conversion processing is performed. However, these conversion processings are integrated into one LUT as a conversion processing (y = g (f (x))). May be processed. In this case, the number of conversion processing systems 40 can be reduced to one as indicated by the two-dot chain line in FIG.

In the above embodiment, when determining the first characteristic and the second characteristic, the G density is used as a classification criterion for image data, but this may be based on another color. G
Average of three colors (R + G + B) instead of density
/ 3 or a weighted average of R, G, B.
Further, a difference or a ratio of color densities such as RGB density and BG density with respect to these reference densities may be used. Note that the first characteristic and the second characteristic relating to the gradation characteristic may be data representing the color balance between the respective colors, data representing the gradation, and the gradation balance, as described above. Including function expressions. Image characteristics include image characteristics such as maximum density and minimum density,
It also includes frequency characteristics, a density histogram, a density cumulative distribution, and conversion values on an isochromatic difference space.

In the above embodiment, the image data storage means 1
The second characteristic is obtained by using the data accumulated in step 9 and is stored in the second characteristic storage means 18. In addition to this, a pattern having a plurality of density areas at the tip of the negative film is printed. The second characteristic may be obtained by reading the developed image density. Also,
In FIG. 1, the original image type identifying means 21, the image data selecting means 20, and the image data accumulating means 19 may be omitted, and the second characteristic data created separately may be stored in the second characteristic storing means 18.

[0042]

According to the present invention, a film having a three-color density balance suitable for a recording material is used as a reference film type, and image data is converted so that various films have the three-color density balance of the reference film type. It is possible to record from a film type or an image with an appropriate color balance from highlight to shadow (a gray subject is reproduced as gray).

Based on the image characteristics suitable for the recording material,
By converting image data so that various films have a standard three-color density balance, it is possible to stably record an appropriate color from any kind of film.

Conventionally, image recording conditions have been determined from the highlight point and shadow point of one original image. However, by accumulating a large amount of image data, a more accurate image processing apparatus and the type of original image used can be obtained. In addition, it is possible to obtain three-color gradation balance data of an original image having no variation between images, and by converting the data into a reference three-color gradation balance,
It is possible to obtain a recorded image having a good color balance from the under image to the over image of the original photographic film, and from the highlight to the shadow in the image.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a main part of a digital printer according to the present invention.

FIG. 2 is a diagram showing an example of a reference film characteristic (first characteristic).

FIG. 3 is a diagram showing an example of film characteristics (second characteristics) obtained for each type of color negative film to be printed.

FIG. 4 is a diagram illustrating an example of a gradation balance conversion table representing a relationship between an R density of a first characteristic and an R density of a second characteristic.

FIG. 5 is a diagram showing an example of an image data conversion table.

FIG. 6 is a diagram illustrating an example of an image data conversion table.

FIG. 7 is a functional block diagram illustrating a main part according to another embodiment.

FIG. 8 is a functional block diagram illustrating a main part according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image signal input means 11 Gradation balance conversion LUT 12 Basic amount calculation means 13 Recording image data conversion LUT 14 Image recording means 15 Gradation balance conversion table creation means 16 Recording image data conversion table creation means 17, 30 First characteristic storage means 18 Second characteristic storage means 19 Image data storage means 20 Image data selection means 21 Original picture type identification means 35 Image memory

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/76-5/956 H04N 9/79-9/898

Claims (8)

(57) [Claims] 1. An image processing method, comprising the steps of:
In the image data conversion method, a conversion condition for obtaining a reference gradation characteristic from a common gradation characteristic of a film type to which the color film belongs is obtained, and the conversion condition is a conversion condition relating to a predetermined reference gradation characteristic.
1 characteristic and gradation stored for each type of the color film
An image data conversion method , which is a conversion table including a second characteristic relating to characteristics, and converting image data using the conversion table . 2. A group of image data from the color film Dzu
In the image data converting method, a conversion condition for obtaining a reference gradation characteristic from a gradation characteristic common to a series of film images of the color film is obtained, and the conversion condition relates to a predetermined reference gradation characteristic.
One characteristic and a series of image data of the color film.
Of the second characteristic relating to the gradation characteristic stored and stored
A table, the image data conversion method and converting the image data by the conversion table. 3. The image data conversion method according to claim 1 , wherein the first and second characteristics are each a color of a film image formed from a neutral color or a subject color approximate to the neutral color. Characterized by the color balance between
Image data conversion method. 4. The image data conversion method according to claim 1 , wherein said first and second characteristics are film characteristic curve data representing a relationship between said film image density and subject brightness. Image data conversion method. 5. The image data conversion method according to claim 1 , wherein the first and second characteristics are color balance characteristics between colors obtained from image data of a large number of film images for each film type. An image data conversion method characterized by the following. 6. The image data conversion method according to claim 1 , wherein said first and second characteristics are determined between each color obtained from image data of a series of many film images including a film image of said color film. An image data conversion method characterized by color balance characteristics. 7. The image data conversion method according to claim 1 , wherein a first characteristic is obtained based on the recording material, and a second characteristic is obtained from image data of a film image. Image data conversion method. 8. An image data conversion device for recording an image on a recording material based on original image data of a color film, wherein: first storage means for recording a first characteristic relating to a predetermined reference image characteristic; A second storage unit for storing a second characteristic relating to the image characteristic obtained from the film, and converting the image data of the color film to be printed into image data of the first characteristic from the first and second characteristics of the two storage units. An image data conversion apparatus comprising: a conversion condition creating unit for creating a conversion condition for converting the image data of a color film to be printed into a first characteristic by storing the conversion condition.