JP2000083170A - Image processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing unit where density data after gradation transformation are not deviated from a valid image density range by a gradation transformation means and gradation is transformed in matching with a gradient of a characteristic curve of an image recording means such as a photo film or a digital camera at all times. SOLUTION: In the case that density data of an image whose gradation is transformed by a gradation transformation means 137 are deviated from a valid image range, a deviation amount (ΔD) of the density data after the transformation from the valid image range is calculated, a correction section 135 parallel-translates a lookup table LUT 1 set to the gradation conversion means 137 by the deviation amount (ΔD) in a direction along with an output density axis within a coordinate plane specified by the LUT 1, and after the gradation transformation means 137 conducts gradation conversion according to an LUT 2 obtained as a result of the parallel translation, a density control section 139 corrects the density data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and, more particularly, to a process for correcting an image for print output on image data obtained by reading an image recorded on a photographic material or a digital camera. The present invention relates to an image processing device.

[0002]

2. Description of the Related Art Conventionally, various types of image processing have been performed on image data obtained by reading a film image recorded on a photographic film by a CCD or the like or image data input from a digital camera or the like. Various output forms, such as recording an image on a recording material such as photographic paper, displaying an image on a display means such as a display, and storing image data on an information recording medium such as a CD-ROM, etc. There is known an image processing system capable of outputting an image.

According to this image processing system, the image quality of an output image can be freely controlled by performing image processing on image data of the image processing system as compared with a conventional photographic processing system that records a film image on photographic paper by surface exposure. Therefore, it is possible to realize high quality of the output image.

[0004] By the way, with respect to a film image recorded on a photographic photosensitive material such as a photographic film, photographing conditions at the time of photographing are not fixed, and illumination conditions for a main subject such as a person are not constant. For this reason, many film images recorded on photographic film include film images whose image quality and the like are not appropriate due to the influence of shooting conditions, lighting conditions for main subjects, and the like.

For example, film images taken by overexposure or underexposure have an overall high or low density,
In addition, the image has a compressed dynamic range. When image processing is performed on the image data of such a film image under the same processing conditions as a normal film image, the output image becomes an image with low contrast and no sharpness.

As shown in FIG. 8, a film image photographed by overexposure or underexposure has a low contrast and no sharpness, as shown in FIG. Is smaller in the exposure amount range corresponding to over or under than in the exposure amount range corresponding to the intermediate density.

The slope of the characteristic curve of a photographic film is linear because it is constant in the exposure range corresponding to the intermediate density, but in the exposure range corresponding to over or under, the color density changes with respect to the change in the exposure. Since the slope of the change is small and changes continuously, it is nonlinear.

[0008] Therefore, in order to correct the film image photographed by overexposure or underexposure so that the gradation becomes constant, as shown in FIG. Density correction is performed according to a gradation conversion condition having a conversion characteristic of converting a characteristic curve of a film so that the inclination of the characteristic curve is apparently linear.

[0009]

However, when the density is corrected in accordance with the above-described gradation conversion conditions, the output of the converted density data is out of the effective image density range as an image, and the resulting print image is black. There is a problem that clipping occurs, such as crushing or flying white.

In order to prevent such clipping, it is conceivable that the density data before conversion is adjusted in advance so that the output of the converted density data falls within an effective image density range, and then the gradation is corrected. Hereinafter, a case will be described in which the density is corrected by the density control unit and then the tone conversion is performed by the tone conversion unit.

First, when the value of density data before gradation conversion and density conversion is x, the conversion characteristic of the density control unit is G (x), and the conversion characteristic of the gradation conversion unit is F (x), OUT obtained through the section and the gradation conversion section is: OUT = F
(G (x)).

When the density control unit adjusts the density data by Δd, the conversion by the density control unit is G (x) =
x + Δd.

The output OUT when the tone conversion is performed by the tone conversion unit after the conversion by the density control unit is given by OUT = F (x + Δd) according to the above equation (2), but F (x) has a strong nonlinearity. Since it has a conversion characteristic, F (x + Δd) ≠ F
(X) + Δd.

In order to convert the density so that the gradation of the output OUT does not change, it is necessary to set OUT = F (x) + Δd. If the conversion by the density control unit remains G (x) = x + Δd. It is inevitable that the gradation changes.

That is, since F (x) has a conversion characteristic with strong nonlinearity, if the value of density data is changed before gradation conversion, the slope of the conversion characteristic corresponding to each density value changes. This deviates from the gradient of the gradation conversion characteristic to be performed, and as a result, there is a problem that the gradation of the printed image cannot be adjusted to be constant. Although the above description has been made with respect to a photographic film, this problem also occurs in a digital camera.

In view of the above, according to the present invention, the density data after gradation conversion does not deviate from the effective image density range, and the input of image recording means such as a photographic film or a digital camera for recording an image of a subject. A first object is to provide an image processing apparatus capable of performing gradation conversion in accordance with the slope of a characteristic curve indicating output characteristics. Also,
It is a second object of the present invention to provide an image processing apparatus capable of keeping the gradation of a print image obtained constant even if the gradation is converted after adjusting the density of the image data in advance.

[0017]

In order to achieve the above object, an image processing apparatus according to claim 1, wherein an image obtained by reading an image recorded on an image recording means for recording an image of a subject is provided. Tone conversion means for inputting density data, converting the input density data according to tone conversion conditions having conversion characteristics based on input / output characteristics of an image recording means for recording an image of the subject, and outputting the converted density data as converted density data When,
When the converted density data deviates from a predetermined effective density range, the conversion characteristic of the gradation conversion condition is set on a plane coordinate for defining the conversion characteristic so that the conversion density data falls within the effective density range. The correction is made so as to have a conversion characteristic translated in a direction parallel to the coordinate axis representing the value after conversion, and the density data of the image obtained by reading the image is input to the gradation conversion means. The image processing apparatus includes a conversion characteristic correction unit and a density correction unit that corrects the converted density data after conversion by the gradation conversion unit so as to change by the set density change amount.

For example, as described above, the characteristic curve of the photographic light-sensitive material is non-linear in the exposure range corresponding to over or under, and the region corresponding to the intermediate density is linear. Is also non-linear in the exposure amount range corresponding to over or under, and linear in the exposure amount range corresponding to the intermediate density.

According to the first aspect of the present invention, the conversion characteristic correcting means adjusts the conversion characteristic of the gradation conversion condition to a value after the gradation conversion so that all the converted density data fall within a valid image range. Since the translation is performed in a direction substantially parallel to the coordinate axis to be represented, it is possible to always correspond to the inclination of the conversion condition corresponding to the density data before gradation conversion.

That is, since the direction of the parallel movement of the conversion characteristic of the gradation conversion condition is substantially parallel to the coordinate axis representing the value after the gradation conversion, the change corresponding to the density data before the gradation conversion is performed. The inclination is always the same.

Therefore, the tone of the image represented by the density data after the tone conversion can always be made constant, and after the tone conversion, the density data is corrected by the set density change amount by the density correcting means. Also, since the gradation of the image represented by the density data after the gradation conversion is constant, the gradation is not changed by this density correction.

The density correction means sets the density change amount based on at least one of the change information input from the outside and the result obtained by analyzing the image, and converts the density data. A modified configuration can be adopted. With such a configuration, for example, for over or under image data, the color density is determined by a user's instruction, and other image data is automatically adjusted based on the image data read at the time of image reading. It becomes possible to make adjustments.

According to a third aspect of the present invention, the input image density data is converted by conversion according to a gradation conversion condition having a conversion characteristic based on input / output characteristics of an image recording means for recording an image of a subject. Tone conversion means for outputting as density data, and a density change amount set along a direction parallel to a coordinate axis representing a value after conversion on plane coordinates for defining conversion characteristics of the tone conversion conditions. The conversion characteristic is corrected so as to have a conversion characteristic that has been translated by a movement amount corresponding to the conversion amount, the density data is converted according to the corrected conversion characteristic, and the obtained density data is inversely converted according to the conversion characteristic before correction. Density conversion means for inputting the density data to the gradation conversion means.

That is, the value of density data before gradation conversion and density conversion is x, the conversion characteristic of the density conversion means is G (x),
When the conversion characteristic of the gradation conversion means is F (x), to convert the density so that the gradation of the output OUT obtained through the density conversion means and the gradation conversion means does not change, OUT = F
(G (x)) = F (x) + ΔD. When this equation is solved for G (x), G (x) = F ⁻¹ (F
(X) + ΔD) is obtained.

That is, when the gradation is converted after the density is corrected, if the density conversion means converts the density so as to satisfy F ^-1 (F (x) + ΔD), it is possible to convert the density before the gradation conversion. Even if the density data is corrected, the gradation of the image represented by the finally obtained output image data is constant.

Therefore, according to the third aspect of the invention, the density conversion means sets the conversion characteristic (F (x)) of the gradation conversion condition along a direction substantially parallel to the coordinate axis representing the converted value. The density data is converted in accordance with the conversion characteristic (F (x) + ΔD) of the converted grayscale conversion condition, and the obtained density data is converted to a level before the correction. The inverse conversion (F ⁻¹ (F (x) + ΔD)) is performed according to the conversion characteristic (F (x)) of the key conversion condition.

The inverse conversion means a conversion characteristic (F) based on a characteristic curve of an image recording means for recording an image of a subject such as a photographic photosensitive material on which an image to be read is recorded.
(X)) is converted to a conversion characteristic F ^{−1 in} which the input-output relationship is reversed.
(X).

Thus, when the density conversion means converts the density data processed by the density conversion means in accordance with the conversion characteristics of the gradation conversion conditions, the gradation of the image represented by the finally obtained image data is constant. become.

The density conversion means sets the density change amount based on at least one of the change information input from the outside and the result obtained by analyzing the image. A configuration in which the shift amount of the conversion characteristic of the gradation conversion condition is set based on the density change amount can be adopted. With such a configuration, for example, for over or under image data, the color density is determined by a user's instruction, and other image data is automatically adjusted based on the image data read at the time of image reading. It becomes possible to make adjustments.

[0030]

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

[First Embodiment] First, a digital lab system according to the present embodiment, which includes an image processing apparatus according to the first embodiment of the present invention, will be described.

(Schematic Configuration of Entire System) FIG. 1 shows a schematic configuration of a digital lab system 10 according to the present embodiment, and FIG.
Is shown. As shown in FIG. 1, the lab system 10 includes a line CCD scanner 14, an image processing unit 16, a laser printer unit 18, and a processor unit 20, and the line CCD scanner 14 and the image processing unit 16 The laser printer unit 18 and the processor unit 20 are integrated as an input unit 26 shown in FIG.
Are integrated as an output unit 28 shown in FIG.

The line CCD scanner 14 scans a film image (photographing a subject, developing processing, etc.) recorded on a photographic material (hereinafter simply referred to as "photographic film") such as a photographic film (for example, a negative film or a reversal film). For example, a 135-size photographic film, a 110-size photographic film, and a photographic film on which a transparent magnetic layer is formed (a 240-size photograph) Film: so-called APS film), 120 size and 22
A film image of a photographic film of size 0 (Brownie size) can be read. The line CCD scanner 14 reads the film image to be read by a three-line color CCD, and outputs R, G, and B image data.

As shown in FIG. 2, the line CCD scanner 14 is mounted on a work table 30. The image processing section 16 is stored in a storage section 32 formed below the work table 30, and an opening / closing door 34 is attached to an opening of the storage section 32. Normally, the inside of the storage unit 32 is concealed by the open / close door 34, and when the open / close door 34 is rotated, the inside is exposed, and the image processing unit 16 can be taken out.

The work table 30 has a display 164 mounted on the back side and two types of keyboards 166A and 166B. One keyboard 166 </ b> A is embedded in the work table 30. The other keyboard 166B is housed in the drawer 36 of the work table 30 when not in use, and is taken out of the drawer 36 when used and is arranged on the keyboard 166A. When the keyboard 166B is used, a connector (not shown) attached to the tip of a cord (signal line) extending from the keyboard 166B,
The keyboard 166 </ b> B is electrically connected to the image processing unit 16 via the jack 37 by being connected to the jack 37 provided on the work table 30.

A mouse 40 is arranged on the work surface 30U of the work table 30. The mouse 40 has a code (signal line) extending through the hole 42 provided in the work table 30 into the storage unit 32.
Is connected to The mouse 40 is stored in the mouse holder 40A when not in use, and is taken out of the mouse holder 40A when in use and placed on the work surface 30U.

The image processing section 16 receives image data (scan data) output from the line CCD scanner 14, receives image data obtained by photographing with a digital camera, and originals other than film images (for example, reflective originals). , Etc.) by scanning with a scanner, computer-generated image data, etc.
It is also possible to externally input these (collectively referred to as file image data) (for example, input via a storage medium such as a memory card or input from another information processing device via a communication line). Is configured.

The image processing section 16 performs, for example, on the input image data, enlargement / reduction of an image, gradation conversion, color conversion, hypertone processing for compressing the gradation of an ultra-low frequency luminance component of the image, and granularity. Various correction processes such as hyper-sharpness processing that emphasizes sharpness while suppressing image data are performed, and the obtained image data is output to the laser printer unit 18 as recording image data. The details will be described later.
Further, the image processing unit 16 outputs the image data subjected to various correction processes to an external device as an image file (for example, outputs the image data to a storage medium such as a memory card, or transmits the image data to another information processing device via a communication line). Etc.) are also possible.

The laser printer section 18 is provided with R, G, and B laser light sources, and irradiates a photographic paper with laser light modulated in accordance with recording image data input from the image processing section 16 to perform scanning exposure. To record an image on photographic paper. Further, the processor unit 20 performs each process of color development, bleach-fix, washing, and drying on the photographic paper on which the image is recorded by the scanning exposure by the laser printer unit 18. Thus, an image is formed on the printing paper.

(Configuration of Image Processing Unit) Next, the image processing unit 1
6 will be described with reference to FIG. Here, the description will be made with emphasis on the configuration of the main part according to the present invention.

The image processing section 16 is provided with a line scanner correction section 122 for performing correction processing in accordance with R, G, and B data input from the line CCD scanner 14. The line scanner correction unit 122 includes a line CCD
When the scan data is input from the line CCD scanner 14 by reading the photographic film, the dark-corrected data for reducing the dark output level of the cell corresponding to each pixel from the input scan data, Density conversion for logarithmic conversion to data representing film density,
Shading correction for correcting the data subjected to the density conversion in pixel units in accordance with the light amount unevenness of the light illuminating the photographic film, and a signal corresponding to the light amount of the incident light is not output among the data subjected to the shading correction. Each process of a defective pixel correction newly generated by interpolating data of a cell (a so-called defective pixel) from data of surrounding pixels is sequentially performed.

The output terminal of the line scanner correction unit 122 is connected to the input terminal of the selector 132, and the data subjected to each of the above-described processes in the line scanner correction unit 122 is input to the selector 132 as scan data. Also,
The input terminal of the selector 132 is also connected to the data output terminal of the input / output controller 134. The input / output controller 134 outputs file image data input from the external input unit 17 to the auto setup engine 1 described later.
The signal is input to the selector 132 via 44.

The output terminal of the selector 132 is connected to the input / output controller 134 and the data input terminal of the image processor 136, respectively. The selector 132 can selectively output the input image data to each of the input / output controller 134 and the image processor unit 136.

The image processor 136 includes a memory controller, an image processor, and a frame memory (not shown). Each of the frame memories has a capacity capable of storing image data of one or more frames of film images, and the image data input from the selector 132 is stored in the frame memory by the memory controller.

The image processor section 136 includes an LUT storage section 133 for storing conversion characteristics F (x) of gradation conversion conditions (hereinafter collectively referred to as LUT (lookup table)). Since the LUT is derived based on the characteristics of the photographic film to be read as shown in FIG. 8, the characteristics differ depending on the type of the photographic film. Therefore, the LUT storage unit 133 stores LUTs corresponding to the characteristics of all photographic films that can be read.

Further, the image processor section 136 includes:
A gradation conversion unit 137 that sets one of the LUTs stored in the LUT storage unit 133 and performs gradation conversion processing, and a correction unit 135 that corrects the gradation conversion characteristic LUT set in the gradation conversion unit 137 (Conversion characteristic correction means) and a density control section 139 (density correction means) for taking in density data of an image subjected to gradation conversion by the gradation conversion section 137 and correcting the density data.

In the image processor 136,
In addition to the above-mentioned gradation conversion processing, for example, well-known images such as image enlargement / reduction, hypertone processing for compressing the gradation of an ultra-low frequency luminance component of the image, and hyper-sharpness processing for enhancing sharpness while suppressing graininess. Processing is also performed.

The auto setup engine 144 to which the image processor unit 136 and the input / output controller 134 are connected includes a CPU, a RAM (for example, a DRAM),
An OM (for example, a rewritable ROM)
These are connected to each other via a bus. The auto setup engine 144 includes an external input / output unit 17 such as a personal computer that outputs image data (file image data) other than image data such as file image data read by the line CCD scanner 14.
And a keyboard 166B to which various instructions are input, and an output terminal of the barcode sensor 14a are connected.

The bar code sensor 14a is a line CCD
The light-emitting element includes a light-emitting element and a light-receiving element provided in a film transport section of the scanner 14, and the light-emitting element irradiates light to a barcode recorded outside the image forming area, and the light-receiving element is blocked by the barcode. In this configuration, the light that has not been received is converted into an electric signal and output. The barcode contains information on the type of photographic film to be read, and the auto setup engine 144 determines the type of photographic film based on the electric signal output from the barcode sensor 14a. The bar code sensor 1
A configuration in which a bar code is read by a CCD without using 4a and the type of photographic film is determined may be input from the keyboard 166B.

The auto setup engine 144 receives an input instruction from the keyboard 166B and the bar code sensor 1
4a, the film type information, L
Processing conditions for image processing, such as the amount of movement of the UT and the amount of density adjustment, are determined by calculation and output to the image processor unit 136.

The output terminal of the image processor 136 is
The image data that has been connected to the input / output controller and has been subjected to various correction processes is temporarily stored in a frame memory (not shown), and then output to the input / output controller 134 at a predetermined timing.

The input / output controller 134 is an I / F circuit 1
It is connected to the laser printer section 18 via 56.
When the image data after image processing is used for recording an image on photographic paper, the image data processed by the image processor 136 is transferred from the input / output controller 134 via the I / F circuit 156 to the recording image. The data is output to the laser printer unit 18 as data. Further, the auto setup engine 144 is connected to the external input / output unit 17. When the image data after the image processing is output to the outside as an image file, the image data processed by the image processor unit 136 is output to the input / output controller 1.
The signal is output to the external input / output unit 17 from the external setup input / output unit 34 via the auto setup engine 144.

(Operation) Next, a control routine stored in the ROM of the auto setup engine 144 in this embodiment will be described with reference to FIG.

First, in step 500, the type of the photographic film to be read is determined from the bar code information at the leading end of the photographic film read by the bar code sensor 14a, and the obtained photographic film information is converted into the gradation conversion unit 13 (step 500).
7 is output.

Thus, based on the input photographic film type information, the gradation conversion unit 137 stores the LUT (hereinafter, LUT1) corresponding to each photographic film type in the LUT storage unit 13
3 and set as gradation conversion characteristics.
The gradation conversion of the density data is performed according to UT1.

In the next step 502, the gradation conversion unit 13
The density data subjected to gradation conversion by the LUT set to 7 is fetched, and it is determined whether or not the fetched density data is within the effective image range. If the gradation-converted density data falls within the effective image range, step 506 is executed.
Then, the density change amount input from the external input / output unit 17 or the density change amount set based on the analysis result of the read image is output to the density control unit 139 (density correction unit). Thereby, the density control unit 139 corrects the density data.

If the density-converted density data does not fall within the effective image range, the flow advances to step 504 to calculate the deviation (ΔD) of the converted image data from the effective image range. , And outputs the obtained result to the correction unit 135 as the movement amount of the LUT1. As shown in FIG. 5, the correction unit 135 includes the LUT 1 set in the gradation conversion unit 137.
Is translated in the direction along the output density axis in the coordinate plane in which the LUT 1 is defined by the deviation amount (ΔD), and a new LU
T (hereinafter, referred to as LUT2). Thus, the tone conversion unit 137 converts the density data (D1) based on the obtained LUT2, and obtains new density data (D2). Then, the process returns to step 502 to determine whether the acquired density data is within the effective image range.

Thereafter, the process proceeds to step 506, where the density change amount input from the external input / output unit 17 or the density change amount set based on the analysis result of the read image is output to the density control unit 139. The density control unit 139 takes in the density data subjected to the gradation conversion, and adjusts the color of the image represented by the density data by correcting the density data (D2) based on the input density change amount.

As described above, according to the first embodiment,
The density data subjected to the tone conversion by the tone conversion unit 137 does not deviate from the effective image density range, and
Since the gradation conversion can be performed according to the inclination of the characteristic curve of the photographic film, the gradation of the obtained printed image can be kept constant.

[Second Embodiment] A digital lab system according to the present embodiment, which includes an image processing apparatus according to a second embodiment of the present invention, will be described. The schematic configuration of the entire system and the configuration of the image processing unit are as follows.
Since it is the same as the first embodiment described above, detailed description is omitted. In the first embodiment, the correction unit 135 forms a conversion characteristic correction unit, and the density control unit 139 forms a density correction unit. In the second embodiment, the correction unit 135 and the density control unit The unit 139 forms a density conversion unit.

(Operation) A control routine stored in the ROM of the auto setup engine 144 in the second embodiment will be described with reference to FIG.

First, in step 600, the type of the photographic film to be read is determined from the bar code information at the leading end of the photographic film read by the bar code sensor 14a, and the obtained photographic film information is converted to the gradation conversion unit 13 (step 600).
7 and the density control unit 139. Density control unit 139
The tone conversion unit 137 reads the LUT 1 corresponding to each photographic film type from the LUT storage unit 133 based on the output film information, and sets each of them.

Next, in step 602, the density change amount (ΔD) input from the external input / output unit 17 or the density change amount (ΔD) calculated by analyzing the read image.
Is output to the correction unit 135. The correction unit 135 is configured as shown in FIG.
As shown in (a), the LUT 1 set in the density control unit 139 is translated by a density change amount (ΔD) in a direction along the output density axis in a coordinate plane in which the LUT 1 is defined, and a new LUT ( Hereinafter, referred to as LUT3).

The density control unit 139 converts the density data (D1) according to the LUT3, and converts the new density data (D2).
Then, as shown in FIG. 7B, the new density data (D2) is converted by the inverse function (LUT4) of LUT1 (in other words, the inverse conversion of LUT1) to obtain density data (D3). .

The density data (D
3) is thereafter subjected to gradation conversion by the gradation conversion unit 137 according to the corresponding LUT 1 based on the output film information, and is output as output density data.

As described above, according to the second embodiment,
Even if the density adjustment is performed before the gradation conversion, the gradation conversion can be performed according to the inclination of the characteristic curve of the photographic film, and there is an advantage that the gradation of the obtained print image becomes constant.

[0067]

As described above, according to the first and second aspects of the present invention, the density data after gradation conversion by the gradation conversion means does not deviate from the effective image density range. There is an effect that the gradation conversion can always be performed in accordance with the inclination of the characteristic curve of the photographic film.

In particular, according to the third and fourth aspects of the present invention, even if the density is adjusted before the gradation conversion, there is an effect that the gradation of the obtained print image can be kept constant.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a digital laboratory system according to a first embodiment.

FIG. 2 is an external view of the digital laboratory system according to the first embodiment.

FIG. 3 is a block diagram illustrating a schematic configuration of an image processing unit in the digital laboratory system according to the first embodiment.

FIG. 4 is a control routine stored in a ROM of an auto setup engine 144 in the image processing unit shown in FIG.

FIG. 5 is a gradation conversion unit 13 corrected by a correction unit 135;
7 is an LUT showing the conversion characteristic of FIG.

FIG. 6 is an auto setup engine 14 in the image processing unit of the digital laboratory system according to the second embodiment.
4 is a control routine stored in the ROM.

FIG. 7 shows the density controller 13 corrected by the correction unit 135.
5 is an LUT showing a density conversion characteristic of No. 5.

FIG. 8 is a diagram showing a characteristic curve of a photographic film.

FIG. 9 is an LUT showing a conventional gradation conversion characteristic matched to a characteristic curve of a photographic film.

[Explanation of symbols]

 14 line CCD scanner 14a barcode sensor 16 image processing unit 17 external input / output unit 18 laser printer unit 20 processor unit 122 line scanner correction unit 132 selector 134 input / output controller 135 correction unit 136 image processor unit 137 gradation conversion unit 139 density control Section 140 Image Processor 144 Auto Setup Engine 156 I / F Circuit 166B Keyboard

Claims (4)

[Claims] An image recording means for recording an image of a subject receives density data of an image obtained by reading the image recorded on the image recording means. The input density data is input to an image recording means for recording an image of the subject. Tone conversion means for converting according to a tone conversion condition having a conversion characteristic based on the output characteristic and outputting the converted density data as conversion density data, wherein when the conversion density data deviates from a predetermined effective density range, the conversion density data is The conversion characteristic of the gradation conversion condition is set so as to fall within the effective density range, and the conversion characteristic is translated along a direction parallel to a coordinate axis representing a value after conversion on plane coordinates for defining the conversion characteristic. Conversion characteristic correction means for inputting the density data of the image obtained by reading the image to the gradation conversion means, Image processing apparatus including a 換濃 degree data, the density correction means for correcting such changed by setting a density change amount. 2. The method according to claim 1, wherein the density correction unit sets the density change amount based on at least one of change information input from outside and a result obtained by analyzing an image, and corrects the converted density data. The image processing apparatus according to any one of the preceding claims. 3. A gray scale for converting input density data of an image according to a gray scale conversion condition having a conversion characteristic based on input / output characteristics of an image recording means for recording an image of a subject, and outputting the converted density data. Conversion means, on a plane coordinate for defining the conversion characteristic of the gradation conversion condition, along a direction parallel to a coordinate axis representing a value after conversion,
The conversion characteristic is corrected so as to have a conversion characteristic translated in parallel by a moving amount according to the set density change amount, the density data is converted according to the corrected conversion characteristic, and the obtained density data is converted to the conversion characteristic before correction. And a density conversion means for performing inverse conversion according to the following formula and inputting the converted density data to the gradation conversion means. 4. The density conversion unit sets a density change amount based on at least one of change information input from outside and a result obtained by analyzing an image, and performs the conversion based on the set density change amount. The image processing apparatus according to claim 3, wherein a moving amount of the characteristic is set.