JP2003242498A - Image processing method, image processor, image output method and image output device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To record an image to which image processing is previously performed to have good image quality, especially gradation. <P>SOLUTION: This image processor processes an image signal for an image output device for outputting an image by gradation-converting an image signal with designated γ-LUT. The processor is provided with a gradation converting means for converting the substantially gradation characteristic about an image outputted by the image output device by performing signal converting processing to the image signal. The gradation converting means converts the gradation characteristic according to the designated transmission density - reflection density characteristic. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and an image processing apparatus for processing an image or outputting an image, an image output method and an image output apparatus. The present invention relates to an image processing method, an image processing apparatus, an image output method, and an image output apparatus suitable for handling the obtained medical image.

[0002]

2. Description of the Related Art Recently, a method for obtaining medical radiation image information without using a radiographic film made of a silver salt photosensitive material has been devised. For example, using an imaging plate mainly composed of a stimulable phosphor, after once accumulating a radiation image, it is taken out as a stimulable luminescent light by using excitation light,
A radiation image reader (Computed Radiograph) that obtains an image signal by photoelectrically converting this light
PHY, hereinafter abbreviated as CR) has become popular.

Recently, a device (Fl) for reading radiation image information by combining a radiation phosphor or radiation photoconductor with a two-dimensional semiconductor detector such as a TFT switching element.
atPanel Detector (hereinafter abbreviated as FPD) has also been proposed.

Further, radiation image input devices other than simple X-ray imaging, such as X-ray computed tomography apparatus (X-ray CT apparatus) and magnetic resonance image forming apparatus (MRI apparatus), are also widespread. These medical image input devices often provide image information in the form of digital signals.

In diagnosing these medical images, a method of recording image information on a transmissive recording medium and / or a reflective recording medium and observing it in the form of a hard copy is often used.

As a medical image recording apparatus for recording medical image information on a recording medium, a method of recording an image by laser exposure on a transmission recording medium using a silver salt recording material is often used. According to this method, a monochrome multi-gradation image can be drawn with excellent gradation, and high diagnostic ability can be obtained by recording on a transparent medium and observing it with transmitted light.

In recent years, the image quality of ink jet recording has been improved with the improvement of miniaturization of ink droplets and improvement of resolution, and paper,
Even when an image is recorded on a reflective recording medium using PET or the like as a support, it has become possible to obtain a certain degree of image quality.

For this reason, recently, the possibility of recording a medical image using an ink jet recording apparatus has been expected.

[0009]

In the ink jet recording system, in order to obtain the same image quality as a reflection image with a transmission image, it is required that at least a high density can be output as compared with the reflection image.

Since the transmitted image is observed by the transmitted light from the back surface of the image, all the ink adhered to the recording medium contributes to the reduction of the transmittance and affects the image density. On the other hand, in the reflection image, since the image is observed by the light reflected from the front surface of the image, only the ink near the surface layer of the recording medium among the inks attached to the recording medium only affects the reflectance and the image density.

For example, if most of the dye remains on the surface of the recording medium, a sufficient image density can be obtained with a relatively small amount of ink. Further, in the reflection image, the reflection density is saturated in the high density region due to the effect of light reflection by external light. On the other hand, in a transmission image, particularly in a medical image, a maximum transmission density of about 3.0 is required, and a large amount of ink is required in order to obtain that density as compared with a reflection image. Further, the running cost may increase due to the use of excessive ink, or the image quality may be impaired due to ink overflow.

Therefore, since the method of forming an image on a transmissive / reflective recording medium is different, it is preferable that the image recording apparatus has a separate γ-LUT for transmissive / reflective recording.

Further, there are cases where the γ-LUT differs depending on the modality (image input device). For example, in a CR image, since an image signal converted into a characteristic similar to a photographic characteristic is obtained as an image signal, an image having a linear density with respect to an image signal value is often output.
On the other hand, since the CT / MRI image has characteristics different from CR, the ideal γ-LUT is generally different from CR.

The inkjet image recording apparatus, which is characterized by low cost, is connected to a LAN such as HIS (in-hospital network) or RIS (radiology network) and POD.
It may be used as a (Print On Demand) printer, but in order to record and transmit images for transmission / reflection for modalities of all forms,
A γ-LUT corresponding to all images may be required.

By the way, in many cases, the gradation is designed by using the density in the transmission image and the brightness in the reflection image due to the difference in the width of the density range. An image recording apparatus that shares a reflection / transmission image has a γ-LUT corresponding to both density and lightness, has some γ-LUT selection means, and records an image based on the selected γ-LUT. be able to.

However, in the image recording apparatus in which the gradation is designed in either the density or the lightness, it is suitable for the image recording of either reflection / transmission, and the other is not suitable. In particular, in a conventional medical image recording apparatus, a transparent image is the mainstream, a centralized processing type having a high processing capacity occupies the majority, and the image recording apparatus may not include a plurality of γ-LUTs.

The present invention has been made in view of the above problems. Even when the image output device has a small number of γ-LUTs, image processing is performed in advance to obtain good image quality, particularly gradation. An object of the present invention is to provide an image processing method, an image processing apparatus, an image output method, and an image output apparatus for recording an image that the user has.

[0018]

[Means for Solving the Problems] That is, the present invention for solving the above-mentioned problems is as follows. (1) The invention according to claim 1 uses an image signal of a predetermined γ-L.
An image processing method for processing an image signal to an image output device which performs gradation conversion by a UT and outputs an image, wherein the image output device outputs an image by performing a signal value conversion process on the image signal. An image processing method comprising: a gradation conversion step of substantially converting a gradation characteristic of an image, wherein the gradation conversion step converts the gradation characteristic based on a predetermined transmission density-reflection density characteristic. Is.

According to a fifteenth aspect of the present invention, there is provided an image processing apparatus which processes an image signal to an image output apparatus which outputs an image by gradation-converting the image signal with a predetermined γ-LUT. By performing signal value conversion processing on
The image output device includes a gradation conversion unit that substantially converts the gradation characteristic of the image output, and the gradation conversion unit converts the gradation characteristic based on a predetermined transmission density-reflection density characteristic. An image processing device characterized by the above.

In these inventions, the image signal is given a predetermined γ-
When the image signal is processed for the image output device that performs gradation conversion by the LUT and outputs the image, by performing the signal value conversion process on the image signal, the image output by the image output device is substantially processed. A gradation conversion step for converting gradation characteristics is provided, and in this gradation conversion step, the gradation characteristics are converted based on a predetermined transmission density-reflection density characteristic.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image processing for recording an image having good image quality, especially gradation.

(2) The invention according to claim 2 is an image processing method for processing an image signal to an image output device which outputs an image by converting the gradation of the image signal by a predetermined γ-LUT. A gradation conversion step of substantially converting gradation characteristics of an image output by the image output device by performing a signal value conversion process on the signal, the gradation conversion step being performed by the image output device. A transmission density gradation characteristic when an image is output on a transmission recording medium and a reflection density gradation characteristic when the image output device outputs an image on a reflection recording medium are substantially the same in a predetermined signal value range. The image processing method is characterized in that

According to a sixteenth aspect of the present invention, there is provided an image processing apparatus which processes an image signal to an image output apparatus which outputs an image by gradation converting the image signal by a predetermined γ-LUT. By performing signal value conversion processing on
The image output apparatus includes a gradation conversion unit that substantially converts gradation characteristics of an image output from the image output apparatus, and the gradation conversion unit transmits the image when the image output apparatus outputs the image on a transparent recording medium. An image processing apparatus characterized in that the density gradation characteristics and the reflection density gradation characteristics when the image output apparatus outputs an image on a reflective recording medium are substantially the same in a predetermined signal value range. is there.

In these inventions, the image signal is given a predetermined γ-
When the image signal is processed for the image output device that performs gradation conversion by the LUT and outputs the image, by performing the signal value conversion process on the image signal, the image output by the image output device is substantially processed. A gradation conversion step for converting the gradation characteristics is provided. In this gradation conversion step, the transmission density gradation characteristics when the image output device outputs the image on the transparent recording medium and the image output device converts the image. The reflection density gradation characteristic when outputting on a reflection recording medium is made substantially the same in a predetermined signal value range.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image processing for recording an image having good image quality, especially gradation.

(3) The invention according to claim 3 is an image processing method for processing an image signal to an image output device for converting the gradation of the image signal by a predetermined γ-LUT and outputting the image. A gradation conversion step of substantially converting gradation characteristics of an image output by the image output device by performing signal value conversion processing on the signal is provided, and the gradation conversion step includes a predetermined brightness-transmission The image processing method is characterized in that gradation characteristics are converted based on density characteristics.

According to a seventeenth aspect of the present invention, there is provided an image processing device which processes an image signal to an image output device which outputs an image by converting the gradation of the image signal by a predetermined γ-LUT. By performing signal value conversion processing on
A gradation conversion unit that substantially converts the gradation characteristic of the image output by the image output device, wherein the gradation conversion unit converts the gradation characteristic based on a predetermined lightness-transmission density characteristic; An image processing device characterized by the above.

In these inventions, the image signal is given a predetermined γ-
When the image signal is processed for the image output device that performs gradation conversion by the LUT and outputs the image, by performing the signal value conversion process on the image signal, the image output by the image output device is substantially processed. A gradation converting step for converting the gradation characteristic is provided, and in this gradation converting step, the gradation characteristic is converted based on a predetermined lightness-transmission density characteristic.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image processing for recording an image having good image quality, especially gradation.

(4) The invention according to claim 4 is an image processing method for processing an image signal to an image output device for converting the gradation of the image signal by a predetermined γ-LUT and outputting the image. A gradation conversion step of substantially converting gradation characteristics of an image output by the image output device by performing a signal value conversion process on the signal, the gradation conversion step being performed by the image output device. The density gradation characteristics when an image is output on a reflective or transmissive recording medium and the brightness gradation characteristics when the image output device outputs an image on a reflective recording medium are substantially the same in a predetermined signal value range. The image processing method is characterized in that

According to the eighteenth aspect of the present invention, there is provided an image processing apparatus which processes an image signal to an image output apparatus which outputs an image by converting the gradation of the image signal by a predetermined γ-LUT. By performing signal value conversion processing on
The image output device includes a gradation conversion unit that substantially converts the gradation characteristics of the image output, and the gradation conversion unit outputs the image onto the reflective or transmissive recording medium by the image output device. In the image processing apparatus, the density gradation characteristics in 1) and the brightness gradation characteristics in the case where the image output apparatus outputs an image on a reflective recording medium are made substantially the same in a predetermined signal value range. is there.

In these inventions, the image signal is given a predetermined γ-
When the image signal is processed for the image output device that performs gradation conversion by the LUT and outputs the image, by performing the signal value conversion process on the image signal, the image output by the image output device is substantially processed. A gradation conversion step for converting gradation characteristics is provided. In this gradation conversion step, the density gradation characteristics when the image output device outputs an image on a reflective or transmissive recording medium, and the image output device And the lightness gradation characteristic in the case of being output on a reflective recording medium are made to have substantially the same shape in a predetermined signal value range.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image processing for recording an image having good image quality, especially gradation.

(5) The invention according to claim 5 is characterized in that the transmission density-reflection density characteristic curve relating to the transmission density-reflection density characteristic is a downwardly convex curve. Image processing method.

The invention according to claim 19 is characterized in that the transmission density-reflection density characteristic curve relating to the transmission density-reflection density characteristic is a downward convex curve.
7 is an image processing apparatus.

(6) According to a sixth aspect of the invention, an image feature amount extraction step of extracting an image feature amount representing a feature of the image, the gradation conversion and other image processing based on the image feature amount. 2. The method according to claim 1, further comprising an execution order determining step of determining an execution order, wherein the gradation conversion and the other image processing are executed according to the execution order determined by the execution order determining step. The image processing method according to claim 5.

According to a twentieth aspect of the present invention, an image characteristic amount extracting means for extracting an image characteristic amount representing an image characteristic, and executing the gradation conversion and other image processing based on the image characteristic amount. Has an execution order determining means for determining the order,
20. The image processing apparatus according to claim 15, wherein the gradation conversion and the other image processing are executed in accordance with the execution order determined by the execution order determining means. is there.

(7) The invention according to claim 7 is the image processing method according to claim 6, wherein the image processing condition in the other image processing is changed according to the execution order.

The invention according to claim 21 is the image processing apparatus according to claim 20, characterized in that the image processing condition in the other image processing is changed according to the execution order.

(8) The invention according to claim 8 is characterized in that the other image processing includes any one of density adjustment processing, dynamic range compression processing, and frequency processing. The image processing method described in any one of 1.

The invention according to claim 22 is characterized in that the other image processing includes any one of density adjustment processing, dynamic range compression processing and frequency processing. The image processing device according to any one of the claims.

(9) The invention according to claim 9 is the image processing method according to any one of claims 1 to 8, characterized in that the image is a medical image. The invention according to claim 23 is the image processing apparatus according to any one of claims 15 to 22, characterized in that the image is a medical image.

(10) According to the tenth aspect of the present invention, there is provided a gradation conversion step of substantially converting gradation characteristics of an image recorded on the image recording apparatus side by performing a signal value conversion process on the image signal. It receives an image signal processed by an image processing device provided and has an output density D (S) with respect to the original image signal S.
Is an image output method for performing gradation conversion according to the γ-LUT and recording an image on a recording medium, wherein the converted image signal after conversion by the gradation conversion step is F (S) with respect to the original image signal S. , The converted image signal difference value ΔFs = F (S + 1) for S that satisfies D (F (S)) ≦ 1.5
−F (S) is 0.2F (Smax) / Smax ≦ | F (S +
1) −F (S) | ≦ 5F (Smax) / Smax, where
Smax is the maximum image signal value in the original image signal S, F (Sm
ax) is the maximum image signal value in the converted image signal F (S)), and has an image output step such that

Further, the invention according to claim 24 is provided with a gradation converting means for substantially converting gradation characteristics of an image recorded on the image recording device side by subjecting the image signal to signal value conversion processing. An image output device that receives an image signal processed by the image processing device, converts the tone of an original image signal S according to a γ-LUT having an output density of D (S), and records the image on a recording medium. , The converted image signal after conversion by the gradation converting means with respect to the original image signal S is F (S)
, The converted image signal difference value ΔFs = F (S + 1) −F (S) for S that satisfies D (F (S)) ≦ 1.5
Is 0.2F (Smax) / Smax ≦ | F (S + 1) -F
(S) | ≦ 5F (Smax) / Smax (where Smax is the maximum image signal value in the original image signal S and F (Smax) is the maximum image signal value in the converted image signal F (S)). An image output device having different image output means.

In these inventions, the image signal processed by the image processing device having the gradation conversion step is received, and γ-L is received.
When gradation-converting according to UT and recording an image on a recording medium, an image output step according to the above formula is included.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image output (image recording) for recording an image having excellent image quality, especially gradation.

(10) The eleventh aspect of the present invention comprises a gradation conversion step of substantially converting gradation characteristics of an image displayed on the image display device side by performing signal value conversion processing on the image signal. An image output method of receiving an image signal processed by an image processing device provided, converting the gradation of an original image signal S according to a γ-LUT whose illuminance on the image display surface is L (S), and displaying the image. , When the converted image signal after the conversion by the gradation conversion step with respect to the original image signal S is F (S), −log ₁₀ (L (F (S))
/Lmax)≦1.5, the converted image signal difference value ΔFs = F (S + 1) −F (S) is 0.2F (S
max) / Smax ≦ | F (S + 1) −F (S) | ≦ 5F (S
max) / Smax, where Smax is the maximum image signal value in the original image signal S and F (Smax) is the converted image signal F
The image output method is characterized by having an image output step such that the maximum image signal value in (S) and Lmax is the maximum illuminance.

Further, the invention according to claim 25 is provided with a gradation conversion means for substantially converting gradation characteristics of an image displayed on the image display device side by performing a signal value conversion process on the image signal. An image output device that receives an image signal processed by the image processing device, converts the gradation of an original image signal S according to a γ-LUT whose illuminance on the image display surface is L (S), and displays the image. The converted image signal after conversion by the gradation converting means is F with respect to the original image signal S.
When (S), −log ₁₀ (L (F (S)) / Lma
x) ≦ 1.5 S after conversion Image signal difference value Δ
Fs = F (S + 1) -F (S) is 0.2F (Smax)
/ Smax ≦ | F (S + 1) −F (S) | ≦ 5F (Smax)
/ Smax, where Smax is the maximum image signal value in the original image signal S, F (Smax) is the maximum image signal value in the converted image signal F (S), and Lmax is the maximum illuminance. An image output device having.

In these inventions, the image signal processed by the image processing apparatus having the gradation conversion step is received, and γ-L is received.
When the gradation is converted according to the UT and the image is displayed on the recording medium, the image output step according to the above formula is included.

As a result, γ-L owned by the image display device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image output (image display) for recording an image having good image quality, especially gradation.

(12) According to the twelfth aspect of the invention, in the image output step, the signal difference value in the low density region is large and the signal difference value in the high density region is small, or
The image output method according to claim 10 or 11, wherein the signal difference value in the high illuminance range is large and the signal difference value in the low illuminance range is small.

According to the twenty-sixth aspect of the invention, in the image output means, the signal difference value in the low density region is large and the signal difference value in the high density region is small, or the signal difference value in the high illuminance range is large. 26. The image output device according to claim 24, wherein the signal difference value in the low illuminance range is small.

(13) The invention according to claim 13 is the image output method according to any one of claims 10 to 12, characterized in that the image is a medical image. The invention according to claim 27 is the image output apparatus according to any one of claims 24 to 26, characterized in that the image is a medical image.

As a result, γ-L owned by the image output device
Even when the number of UTs is small, it is possible to perform image processing in advance and realize image output for recording a medical image having excellent image quality, especially gradation.

(14) The invention according to claim 14 is an image output method for recording a medical image on a reflective recording medium,
An image output method comprising a background detection step of detecting a background area in a medical image, and replacing the reflection density in the background area with a signal of a density uniform area of 2.0 or less.

The invention according to claim 28 is an image output device for recording a medical image on a reflective recording medium, comprising a background detecting means for detecting a background region in the medical image, and the reflection density in the background region. Is replaced with a signal of a density uniform region of 2.0 or less.

In these inventions, when outputting a medical image on a reflective recording medium, the background area in the medical image is detected and the reflection density in the background area is a signal of a uniform density area of 2.0 or less. Have been replaced with.

As a result, a medical image suitable for observation can be recorded on the reflective recording medium.

[0059]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the configurations, operations, numerical values, etc. of specific examples described in the embodiments below.

First, in the following embodiments, the definitions of terms used in the description will be clarified. "Γ-LUT"
Means a characteristic of an image output value obtained with respect to an image signal value, and the image output device outputs an image based on this γ-LUT.

"Outputting" an image means embodying the image on an output object based on an image signal representing the image.
Mainly "recording" images, or "displaying" images
Corresponds to the act of doing.

The "output density" is the density of the output product obtained when the image is output, and the "output illuminance" is the illuminance of the output product obtained when the image is output. “Density” represents so-called optical density D, and DT = −log
It is defined by ₁₀ T or DR = −log ₁₀ R. For example, it refers to the density measured by an optical densitometer PDM-65 (manufactured by Konica Corporation). Note that T and R are light transmittance and reflectance, respectively. The former density is called the transmission density, and the latter density is called the reflection density. Since the present invention can be applied to both the transmission density and the reflection density, the density means either the transmission density or the reflection density unless otherwise specified. In addition, the density of the image refers to the density of the entire image including the density of the recording agent attached to the recording medium and the density of the recording medium.

"Brightness" means the CI recommended by CIE1976.
The lightness in the E-LAB color system, which is a kind of psychophysical quantity that well expresses the degree of light and shade. The "signal value conversion process" is a process of converting an "original image signal" into a "converted image signal" in accordance with a gradation conversion step. In addition,
The "original image signal" is an image signal before the gradation conversion step according to the present invention is executed, and the "post-conversion image signal" is an image signal after the gradation conversion step according to the present invention is executed. Is.

The original image signal S can take any value among integers in the range of 0≤S≤Smax.
max is the maximum image signal value in the original image signal,
When the unprocessed image signal is an image signal forming N-bit gradation, Smax = 2 ^ N-1. Post-conversion post-conversion image signal S ′ can take any value among integers in the range of 0 ≦ S ′ ≦ S′max, where S′max is the maximum image signal value in the post-conversion image signal. That is, for example, when the converted image signal is an image signal forming an M-bit gradation, S'max = 2 ^ M-1. Further, in the gradation conversion processing in the present embodiment, since the original image signal S is converted into a converted image signal according to a predetermined law, the converted image signal is referred to as F (S) in order to clarify its definition. There is also.

The "gradation conversion step" is a process of substantially converting the gradation characteristics of an image output from the image output device by performing a signal value conversion process on the original image signal.

The "gradation characteristic" is a characteristic showing the relationship between the signal value in the image signal and the physical quantity or psychophysical quantity. For example, the "density gradation characteristic" is a characteristic indicating the relationship between the signal value and the density, and the "density gradation characteristic curve" is the gradation characteristic in which the horizontal axis is the signal value and the vertical axis is the density. Shall be represented. Further, the terms "brightness gradation characteristic" and "brightness gradation characteristic curve" are defined by replacing "density" with "brightness" in the above definition. Further, when the "transmission density gradation characteristic" or "reflection density gradation characteristic" is specified, "transmission density"
The gradation characteristic is related to "reflection density".

The "transmissive recording medium" is a recording medium whose main purpose is to observe it as a transmitted image, and the "reflective recording medium" is a recording medium whose main purpose is to observe it as a reflected image.

The gradation characteristic being "substantially the same" means that the two numerical values have exactly the same value and, of course, have the relationship of being multiplied by a predetermined proportional coefficient γ. For example, if the reflection density characteristic is substantially the same as the transmission density characteristic, DR = γ · DT + a (a is a constant)
Is a relationship.

The phrase "in a predetermined signal value range" means nothing but a signal value range that can be arbitrarily set. However, in practice, image output (image recording,
This means the range of gradation required for image display. For example, the "predetermined signal value range" is within the range of DT <2.0 in transmission density, DR <1.5 in reflection density, and L *> 10 in brightness.

A side having a high density with the predetermined density as a boundary is called a "high density side", and a side having a low density is called a "low density side".
When an image is output based on the γ-LUT of the image recording apparatus, the signal value when the output density belongs to the high density side is called the “signal value on the high density side”, and when the output density belongs to the low density side. The signal value of is referred to as a “signal value on the low density side”.

The "signal difference value" represents the difference value in the image signal. The converted image signal corresponding to the (n + 1) th smallest image signal S = n in the original image signal is F
(N), where the converted image signal corresponding to the (m + 1) th smallest image signal S = m in the original image signal is F (m), the original image signal difference value ΔSn, m is Sn, m = n− m, the converted image signal difference value ΔS′n, m is ΔS′n, m = F (n)
-F (m).

FIG. 1 shows an image processing apparatus 10 according to this embodiment.
FIG. 2 is a configuration diagram showing an overall configuration of 0 and the image output device 200. In this embodiment, the image output apparatus 200 outputs (records or displays) an image after the signal value conversion processing is performed on the image processing apparatus 100 side. As described above, the signal value conversion process is executed on the image processing apparatus 100 side before the output, thereby substantially converting the gradation characteristic (gradation conversion).

Here, the image output device 200 such as an image recording device or an image display device is designed with gradation characteristics such that the output transmission density DT is linear with respect to the image signal S. That is, based on the image signal S, the image output device 20
When an image is output at 0 (input 1), as a result, a linear transmission density gradation characteristic (FIG. 1) is obtained for the image signal value as designed (output 1).

On the other hand, when the gradation conversion processing by the image processing apparatus 100 is executed on the original image signal S, the signal value conversion processing as shown in FIG. 1 is performed and the converted image signal S'is obtained.

The converted image signal S ′ is the image output device 2
When it is input to 00 (input 2), as a result, the gradation curve is gentle at a low signal value and the gradation curve is abrupt at a high signal value (hereinafter, referred to as “low steep high slow monotonous increase curve”). An image having the transmission density gradation characteristic (FIG. 1) is obtained (output 2). In this way, the gradation characteristics can be substantially converted by subjecting the image signal to signal value conversion processing in advance and then outputting the image.

The image output device 200 outputs (records or displays) an image based on the γ-LUT.
Here, “γ-LUT” refers to the characteristic of the image output value obtained for the image signal value.

The image output value is an output value such as a physical quantity obtained by measurement from an output product or a psychophysical quantity corresponding to sensory evaluation. In the image recording apparatus, the density, brightness,
In the image display device, it refers to brightness, illuminance, and the like.

FIG. 2 is a gradation conversion means for converting the transmission density gradation characteristics and the reflection density gradation characteristics to substantially the same shape at least in a predetermined signal value range by outputting an image after the signal value conversion processing. It is explanatory drawing about the signal processing apparatus 100 provided with.

That is, the gradation conversion by the above-mentioned signal value conversion processing is performed by the image output apparatus 200 when the image is output onto the transmissive recording medium and the transmission density gradation characteristic, and the image output apparatus 200 converts the image into the reflective recording medium. The reflection density gradation characteristics in the case of outputting to the above are made to have substantially the same shape in a predetermined signal value range.

The image output device 200 is designed with gradation characteristics such that the output transmission density DT is linear with respect to the original image signal S. When the original image signal S is input to the image output device 200 (input 3), as a result, an image having the gradation characteristic as designed (FIG. 2) is obtained in the transmission density, while the gradation curve is obtained in the low signal value in the reflection density. Is a monotonous increase curve where the gradation curve is gentle and the gradation curve is abrupt at high signal values (hereinafter referred to as the “low gentle high sudden monotonous increase curve”).
) Image is obtained (output 3).

Here, when the gradation conversion processing by the image processing apparatus 100 is executed on the original image signal S, the signal value conversion processing as shown in FIG. 2 is performed and the converted image signal S'is obtained. .

The converted image signal S ′ is output to the image output device 2
When input to 00 (input 4), as a result, an image having a transmission density characteristic of a low-smooth, high-quick monotonically increasing curve in transmission density (FIG. 2) is obtained, whereas in the reflection image, the reflection density is linear with respect to the image signal. An image having a gradation characteristic (FIG. 2) is obtained (output 4).

As described above, the transmission density gradation characteristic and the reflection density gradation characteristic can be converted into substantially the same type by outputting the image after the original image signal S is subjected to the signal value conversion processing in advance.

When an ink jet recording apparatus for forming an image by combining a recording medium and a coloring material is applied as the image output apparatus 200, the maximum transmission density differs depending on the type of recording medium, and the reflection density is usually different. It is hard to come out.

FIG. 3 is a gradation conversion means for converting the transmission density gradation characteristic and the reflection lightness gradation characteristic to at least approximately the same type within a predetermined signal value range by outputting an image after the signal value conversion processing. It is explanatory drawing about the signal processing apparatus 100 provided with.

That is, the density gradation characteristics when the image output apparatus 200 outputs an image on a reflective or transmissive recording medium, and the lightness gradation characteristics when the image output apparatus 200 outputs an image on a reflective recording medium. , Have substantially the same shape in a predetermined signal value range.

Here, the image output device 200 is designed with gradation characteristics such that the output transmission density DT is linear with respect to the original image signal S. Then, when the original image signal S is input to the image output device 200 (input 5), as a result, an image having the gradation characteristics as designed (FIG. 3) is obtained in the transmission density, while the reflection density is low at the low signal value. The tone curve is gentle and the tone curve is steep at high signal values.
It is called a "low-slow high-quick monotonically decreasing curve". ) Is obtained (output 5).

Here, when the gradation conversion processing by the image processing apparatus 100 is executed on the original image signal S, the signal value conversion processing as shown in FIG. 3 is performed, and the converted image signal S '
Is obtained.

The converted image signal S ′ is output to the image output device 2
When input to 00 (input 6), as a result, an image having a characteristic of a low-slow high-quick monotonic decrease curve in transmission density (FIG. 3) is obtained, whereas in the reflection image, the reflection lightness is linear with respect to the image signal. An image having gradation characteristics (FIG. 3) is obtained (output 6).

As described above, the transmission density gradation characteristic and the reflection lightness gradation characteristic can be converted into substantially the same type by outputting the image after the signal value conversion processing is performed on the image signal in advance.

FIG. 4 is an explanatory diagram of a method of converting gradation characteristics based on a predetermined output density characteristic. The output density characteristic here means a transmission density-reflection density characteristic curve (transmission density on the horizontal axis and reflection density on the vertical axis).

FIG. 4A shows the same image output device 200.
When an image is output (recorded or displayed) based on the same image output method (image recording method or image display method) using, the transmission density gradation characteristics and reflection in the case of recording an image on the transparent recording medium T The reflection density gradation characteristics ′ when an image is recorded on the recording medium R are shown.

The transmissive recording medium T and the reflective recording medium R do not necessarily have to be the same or the same type of recording medium, and may be a combination of different ink receiving layers and different supports. The maximum and minimum densities in the transmission image are DTmax and DTmin, respectively, and the maximum and minimum densities in the reflection image are DRmax and DRmin, respectively.

FIG. 4 "is a transmission density-reflection density characteristic curve when an image is output based on an image signal (referred to as" inherent density characteristic curve "). Here, the reflection density has a characteristic of being convex upward with respect to the transmission density.

FIGS. 4 (b-1) to 4 (d-2) are characteristic diagrams showing the gradation characteristics when the image signal value conversion processing is performed in advance by the image processing apparatus 100 and then the image is recorded. . If the predetermined output density characteristic is designed to match the characteristic density characteristic curve (FIG. 4 (b-1)), it is not necessary to perform any gradation conversion on the image signal, so S =
The image may be output as S ′ (FIG. 4 (b-2)).

If the predetermined output density characteristic is the transmission density, the reflection density is a straight line in the entire density range (see FIG. 4 (c-
1)), the image processing apparatus 100 preliminarily performs signal value conversion processing such that the original original image signal S as shown in FIG. 4C-2 is convex downward. You can output the image after you go to.

FIG. 4 (d-1) shows a case where the gradient between the transmission density and the reflection density is 1, and the reflection density becomes constant above a predetermined transmission density. FIG. 4 (d-2) corresponds to FIG.
It corresponds to -1), and shows a case where the reflection density is a function convex downward with respect to the transmission density at a predetermined density or less. That is, the image processing apparatus 100 may perform such signal value conversion processing in advance and then output the image.

When the gradient in the transmission density-reflection density characteristic curve is a linear value of 1, the two densities appear to match, but in an actual diagnostic image, the gradient in the transmission density-reflection density characteristic curve is less than 1, Furthermore, it was confirmed by sensory evaluation that when the transmission density-reflection density characteristic curve is a downward convex curve, it has suitable gradation characteristics. Therefore, it is preferable to perform the density gradation conversion so as to have such a characteristic curve.

FIG. 5 is a diagram showing an example of the execution order of the gradation conversion processing and the other processing. The gradation conversion processing is executed according to an appropriate execution order. That is, in the image processing apparatus 100, an image feature amount extraction unit that extracts an image feature amount that represents an image feature, and an execution order of the gradation conversion and other image processing are determined based on the image feature amount. And an execution order determining means.

Then, the gradation conversion processing and other image processing (density adjustment processing, frequency enhancement processing, dynamic range compression processing, etc.) are executed in accordance with the execution order determined by the execution order determining means.

As described above, the gradation conversion processing is executed in an appropriate execution order in consideration of the order of the other processing according to the feature amount of the image, so that the information loss due to the quantization error may occur.
It is possible to perform desired image processing without performing unintended frequency emphasis or dynamic range compression that would rather deteriorate image quality due to the processing.

FIG. 6 is a diagram showing an example of the density correction processing. The density correction process is a process for correcting a predetermined structure in an image (in a medical image, an organ, a bone, etc.) so as to output a predetermined density. Since doctors or radiologists observe diagnostic images under almost the same environment, it is desired that images are always output with the same gradation characteristics. For example, regarding the diagnostic image, the preferable transmission density of the mammary gland in mammography is set to 1.5 to 2.0. Also,
Since the output density ranges of the transmission density and the reflection density are different, the appropriate density of the predetermined structure may be different, or may be different depending on the type of recording medium on which an image is recorded.

FIG. 6A shows an image signal histogram in a medical image. When the image signal value corresponding to the predetermined structure is S1, it is assumed that the image signal value corresponding to the proper density in the predetermined structure is S2.

FIG. 6B shows a new image signal histogram obtained by the density correction processing. By adding a certain signal value to the original image signal, the image signal histogram was shifted to the high signal value side, and the image signal value in the predetermined structure was S2, and the proper density could be obtained.

If the difference between the ideal output density and the actual output density is extremely small, it is sufficient to perform the primary conversion of the image signal. That is, the processing can be performed according to the arithmetic expression of Snew = a · Sorg + b. However, when the difference between the ideal output density and the actual output density is large, a more suitable density correction process can be performed by performing a more complicated arithmetic expression than the linear conversion.

FIG. 7 is a diagram relating to the execution order of the gradation conversion processing and the frequency processing, showing the difference in the frequency processing effect due to the change of the execution order. In the frequency processing, for example, the sharpness can be controlled by using the blur mask processing shown in the following formula (1). Incidentally, this control is performed in Japanese Patent Application Laid-Open Nos. 55-163472 and 62-62373.
JP-A-62-62376 and the like. Sproc = Sorg + β × (Sorg−Sus) (1), (Sproc: frequency-enhanced signal, Sorg: original image signal, Sus: blurred image signal, β: enhancement coefficient) In addition, recently, an image processing method has been adopted. Improvements have been made so that a clearer processing effect can be obtained by the multi-resolution method. The multi-resolution method is a method in which an original image signal is decomposed into image signals in a plurality of frequency bands, predetermined image processing is applied, and then the entire image is restored to obtain a processed image signal. Image processing using multi-resolution is (Digital
Image Processing: Springe
r-Verlag 1991). For example, according to Japanese Patent Laid-Open No. 10-75395, the following formula (2), Sproc = Sorg + β (Sorg) · Fusm (Sorg, Sus1, Sus2, ... SusN), Fusm (Sorg, Sus1, Sus2, ... SusN). ) = {F1 (Sorg-Sus1) + f2 (Sus1-Sus2) + ... + fk (Susk-1-Susk) + ... + fN (SusN-1-SusN)} (2) (However, Sproc: high frequency component is emphasized. Image signal, S
org: original image signal, Susk (k = 1 to N): non-sharp mask image signal, fk (k = 1 to N): function for converting each band-limited image signal, β (Sorg): to original image signal There is a description that image processing should be performed in accordance with the emphasis coefficient determined based on the above.

FIG. 8A-1 is a characteristic diagram of gradation conversion processing. The converted image signal S ′ with respect to the original image signal S is a curve that is convex upward. The frequency processing is Snew = Sorg +
Frequency processing is performed based on the formula of β (Sorg) (Sorg-Sus).

Here, the case where the execution order of the gradation conversion processing and the frequency processing is changed will be considered. . Figure 8 (a-2)
Is an example of the enhancement coefficient β (Sorg) when the frequency process is first performed and the gradation conversion process is subsequently performed. S <S1
, Β (Sorg) is constant, β (Sorg) increases as S increases in S1 <S <S2, and β in S> S2
(Sorg) is constant. In this way, when β (Sorg) is determined, the effect of suppressing the emphasis in the low signal range and the high signal range can be obtained.

FIG. 8 (b-1) shows the enhancement coefficient β (Sorg) in the case where the gradation conversion process is first performed and then the frequency process (FIG. 8 (b-2)) is performed. The coefficient for obtaining the same effect as -2) is shown. The signal values S1 and S2 at which the emphasis characteristic changes are F ⁻¹ (S1) and F ⁻¹ (S
Change to 2). It should be noted that F ⁻¹ (·) corresponds to the inverse function in S ′ = F (S), and the change point of the emphasis degree shifts to the low signal side. As described above, it is necessary to change the processing parameter when the execution order is different. Strictly speaking, the same images are not obtained, but almost the same frequency enhancement feeling is obtained. Therefore, a frequency emphasis degree table can be created according to the order of image processing, and the emphasis degree can be selected according to the execution order. Then, similar frequency characteristics can be obtained regardless of the execution order.

FIG. 9 is a diagram relating to the execution order of the gradation conversion processing and the dynamic range compression processing, and is a view showing the difference in the effect of the dynamic range compression processing due to the change of the execution order.

FIG. 9A-1 is a characteristic diagram of gradation conversion processing. The converted image signal S ′ with respect to the original image signal S is a curve that is convex upward. Here, a case where the execution order of the gradation conversion processing and the dynamic range compression processing is changed will be considered.

The dynamic range compression process is performed by S
Frequency processing is performed based on the formula new = Sorg + F (Sus) (FIG. 9a-2). Snew = Sorg + F (Su
s), F (Sus) = β (Sus) {A-Sus}, Sorg: image signal, Sus: image signal after non-sharp mask processing,
F (•): Non-linear function, which is a monotonically non-increasing function with respect to the signal value.

FIG. 9B-1 shows the characteristics when the dynamic range compression processing is performed first, and the nonlinear function F when the gradation conversion processing (FIG. 9B-2) is performed later.
It is an example of (Sus). When Sus <S1, F (Sus) monotonically decreases when the slope is −β1 and reaches F (Sus) = 0 when Sus = S1. For S1 <Sus <S2, F for all Sus
(Sus) = 0. When Sus> S2, the slope of F (Sus) decreases monotonically when the slope is -β2. In this way, when F (Sus) is determined, the signal value increases in the low signal range and the signal value decreases in the high signal range, and the effect of compressing the dynamic range is obtained.

FIG. 9A-2 shows a nonlinear function F (Sus) in the case where the gradation conversion process is first performed and the dynamic range process is subsequently performed, and the same effect as that of (b-1) is obtained. Represents a function to obtain. As described above, it is necessary to change the processing condition (processing parameter) when the image processing execution order is different.

By performing the dynamic range compression process, it is possible to change the density range while maintaining the contrast (signal difference) in the intermediate density range, at least in the range of S1 <Sus <S2. Particularly in a reflection image, it is possible to reduce the maximum signal value in the image without reducing the contrast. Usually, the ink amount increases in the high density range, so that the ink amount can be saved and the ink overflow can be prevented.
Also, the thermal transfer method is suitable for energy saving because it does not require excessive heating.

Next, the image feature amount of the image signal and its extraction method will be described. First, the gradation expression capability will be described. "Gradation representation ability" is synonymous with the number of expressible gradations, and basically, the larger the number of gradations, the higher the gradation representation ability. In the case of a digital output device, since rounding error (hereinafter referred to as “quantization error”) due to quantization causes deterioration of image information, when the number of expressible gradations is large, the quantization error associated with quantization is reduced. Is. Since it is practically difficult to increase the number of gradations from an image signal having a small amount of image information by an image output device, it is important to maintain the image information while performing the image processing. In a medical image, a density range important for diagnosis (DT <2.0 in transmission density, DR <1.5 in reflection density, L *> 1 in lightness)
Equivalent to 0. ), Especially at low signal levels,
Higher gradation expression is preferable.

In order to check the change in gradation expression ability before and after the gradation conversion processing, the converted image signal difference value ΔS′n + 1, n = F corresponding to the closest image signal value in the original image signal.
The change in the value of (n + 1) -F (n) may be investigated.

FIG. 9 is a diagram showing the signal difference value of the image signal after gradation conversion. FIG. 9A-1 shows a signal value conversion characteristic, which is a convex curve. For simplicity, consider a case where the number of gradations before and after the gradation conversion processing is the same (N-bit gradation → N-bit gradation). FIG. 9A-2 shows the difference value characteristic of the converted signal value. In addition, ΔS 'in the figure
Represents the same as the converted image signal difference value ΔS′n + 1, n. The number of gradations substantially increases in the region of ΔS ′> 1, but the number of gradations substantially decreases in the region of ΔS ′ <1.

On the other hand, FIG. 9B-1 shows the signal value conversion characteristic, which is a downwardly convex curve. FIG. 9B-2 shows the difference value characteristic of the converted signal value. The number of gradations substantially increases in the region of ΔS ′ <1, but the number of gradations substantially decreases in the region of ΔS ′> 1.

Thus, if | ΔS'n + 1, n | =
If it is 1, the gradation representation ability before and after the gradation conversion processing is the same,
If ΔS'n + 1, n |> 1, the gradation expression capability is improved, and | Δ
If S′n + 1, n | <1, the gradation expression capability is deteriorated. Generally, a gradation conversion process in which the number of gradations in the original image signal is an image signal forming an N-bit gradation and the number of gradations in the converted image signal is an image signal forming an M-bit gradation. Is ΔS'th
= S'max / Smax = (2 ^ M-1) / (2 ^ N-1).

The present inventor conducted the following sensory evaluation in order to investigate the limit of gradation expression ability. A 12-bit (4096 gradation) grayscale image signal is created, and based on the image signal obtained by subjecting the image signal to various gradation conversion processes, a silver salt laser image recording device Li-62P (manufactured by Konica Corporation) The image was output with and the gradation expression ability was visually evaluated.
As a result, 0.2F (Smax) / Smax ≦ | ΔS′n + 1,
It was confirmed that when n | ≦ 5F (Smax) / Smax, good gradation was obtained.

When a 12-bit original image signal is output by an 8-bit compatible image output device, the number of gradations decreases due to a quantization error, and the gradation expression capability deteriorates. The property of the finally obtained image signal differs depending on the order of the gradation conversion process and other various image processes. Arithmetic processing is performed on the quantized original image signal, and the arithmetic result is quantized. That is,
The more information of the image signal before processing, the more rigorous arithmetic processing using the information originally possessed by the original image signal can be performed. On the other hand, when the 8-bit original image signal is output by the 12-bit compatible image output device, the number of gradations is maintained. When performing the dynamic range compression processing or the frequency processing, it is preferable to increase the number of gradations because the quantization error is reduced.

Since the low density range has a better density resolution than the high density range, it is preferable that the gradation expression ability in the low density range is high. Therefore, it is preferable that the image output device (recording device and display device) is designed so that the gradation expression performance becomes higher toward the lower density side.

FIG. 10 is a flow chart showing the execution order determining step. The execution order of the dynamic range compression processing, the density correction processing, and the gradation conversion processing will be described as an example. For simplicity, the dynamic range compression process and the density correction process are always performed first in the order of the dynamic range compression process. First, the number of gradations N bits (the number of gradations 2 ^ N) in the original image processing is compared with the number M of gradations (the number of gradations 2 ^ M) in the processed image processing. If N> M, finally The gradation conversion processing is executed. If N ≦ M, the execution order of the gradation conversion processing and the dynamic range compression processing is determined. Converted image signal difference value | ΔS'n +
1, n | and the threshold value ΔS'th that determines the tone expression capability determine the execution order. If | ΔS'n + 1, n | <ΔS'th, the dynamic range compression process is executed first. , Otherwise, the gradation conversion processing is executed first. In this way, the execution order of each image processing can be determined based on the image feature amount, and the optimum image processing according to the image signal can be performed.

In the embodiment of FIG. 10, the order of the dynamic range compression processing and the density correction processing is fixed in advance, but the order is not limited to this. For example, the processing order of the gradation conversion processing and the density correction processing may be determined based on the values of the pre-correction image signal Sorg and the post-correction image signal Snew in the predetermined structure. In particular,
Change width of original image signal before gradation conversion processing Sshift =
| Sorg-Snew | and the change width S'shift = | S'org-S'new | of the converted image signal after the gradation conversion processing are obtained, and (Sshift / Smax) ≧ (S'shift / S'm
If ax), the density conversion processing is performed after performing the gradation conversion processing, and if (Sshift / Smax) <(S'shift / S'max), the density conversion processing is performed and then the gradation conversion processing is performed. do it. Although frequency processing is not included in FIG. 10, when frequency processing is also executed, the execution order may be determined according to a predetermined rule.

It is preferable to change the image processing conditions (processing parameters etc.) according to the execution order determined by the above method. For example, an emphasis coefficient in frequency processing, a mask size, a gradient in dynamic range compression processing, a mask size, etc. correspond to this.

FIG. 11 is a diagram showing an example of converting the density of the back surface portion of the image which is not the subject area. Here, the threshold value Sth = 230 is set, and a process of replacing pixels having a signal value equal to or higher than the threshold value Sth with Snew = 200 is executed. The determination may be made simply by using a threshold value, but in some cases, the object area may have a signal value equal to or higher than the threshold value. Therefore, in order to recognize the region in the back surface with higher accuracy, if the signal value is S> Sth, and S> Sth is satisfied in a predetermined number of peripheral pixels.
If is true, a method of determining that area as the back area may be used.

FIG. 12A shows a general X-ray CT image. The back portion is an area where X-rays are transmitted as it is at the time of photographing, that is, a so-called blank area, and the background portion has a density close to the maximum output density. FIG. 12B is an image in which the back area of the image is recognized and its density is replaced with medium density. FIG. 12C is an image in which the back area of the image is recognized and its density is replaced with low density.

In the first place, the effect has been obtained because it has the effect of reducing the amount of light entering the retina from the amount of light emitted from Schaukasten, room lighting, and other light sources during image observation. There is almost no cost to darken the back part. However, the thermal transfer method requires a heat quantity, and in the ink jet type recording apparatus, since the recording medium and the recording agent are separated, the consumption of the recording agent increases as the output density is increased, and the cost is high. turn into. In the transmitted image, it is necessary to block the direct light from the Schaukasten, but in the reflected image, the Schaukasten is not required. Therefore, the image is observed with external light (mostly indoor lighting). No need for shading. Therefore, it is preferable to recognize the background portion and make the background density lower than the actual output density so as to have a certain light-shielding effect in order to save the recording material.

For example, when DT = 1.0, the amount of reflected light in the back surface region can be reduced to 1/10 as compared with DT = 0.0. Therefore, a great effect can be obtained for the purpose of shielding light. If DT <2.0, it is possible to obtain an image that is not so unnatural as compared with a medical image obtained by conventional film development.

The present invention can be applied not only to the image recording device but also to an image display device (so-called display device). However, in the image display device, the physical quantity representing the shading of the image is the "density" in the image recording device.
Although not so clear, it can be expressed using the illuminance or brightness in the vicinity of the image display surface. As a result of the study by the present inventor, it was confirmed that when the physical quantity applied when obtaining the gradation characteristic is the logarithmic value of the illuminance, almost the same result as the "density" in the image recording apparatus can be obtained. The image display device to which the present invention is applicable may be a display such as a CRT, a transmissive or reflective liquid crystal display, an organic EL display, and a plasma display, and is not limited to a display system.

The present invention can be applied to all image output devices regardless of the output system, application and monochromatic / multicolor. In particular, it is effective in a field having an image signal for monochrome multi-gradation and requiring extremely high image quality, such as a medical image, because the effect of improving the gradation property remarkably appears.

[0133]

As described above with reference to the embodiments, even when the number of γ-LUTs owned by the image output apparatus is small, the image processing is performed in advance to obtain an image having good image quality, especially gradation. Can be recorded.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing characteristics relating to characteristic portions of the image recording apparatus according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing characteristics relating to characteristic portions of the image recording apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a processing state according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 9 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 10 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 11 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

FIG. 12 is an explanatory diagram showing characteristics of the image recording apparatus according to the embodiment of the present invention.

[Explanation of symbols]

100 image recording device 101 control means 110 image processing means 120 recording head unit 130 Conveyor roller 140 recording head conveying means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61B 6/03 G06T 1/00 290A G06T 1/00 290 H04N 1/40 101E H04N 1/407 A61B 6/00 350M 5/325 350A // A61B 5/055 350N G01R 33/32 5/05 380 G01N 24/02 520Y F term (reference) 4C093 AA26 CA01 CA21 DA06 FD03 FF08 FF09 FF18 FF33 FF34 FF50 4C096 AB07 A11 A12 AD12 DC12 FC13 BA30 CE04 CE06 CE11 CH07 CH18 DC23 5C077 LL17 LL19 MP01 PP02 PP15 PP43 PP47 PQ08 PQ19 PQ23 RR06 RR11 TT02 TT10

Claims (28)

[Claims] 1. An image processing method for processing an image signal to an image output device, which performs gradation conversion of an image signal with a predetermined γ-LUT and outputs an image, wherein signal value conversion processing is performed on the image signal. Accordingly, a gradation conversion step for substantially converting gradation characteristics of an image output by the image output device is provided, and the gradation conversion step includes gradation characteristics based on a predetermined transmission density-reflection density characteristics. An image processing method comprising: 2. An image processing method for processing an image signal to an image output device for converting the gradation of an image signal by a predetermined .gamma.-LUT and outputting the image, wherein the signal value conversion process is performed on the image signal. Accordingly, the image output device includes a gradation conversion step of substantially converting gradation characteristics of the image output, wherein the image conversion device outputs the image onto a transparent recording medium. An image characterized in that the transmission density gradation characteristic in the case and the reflection density gradation characteristic in the case where the image output device outputs the image on the reflection recording medium are substantially the same in a predetermined signal value range. Processing method. 3. An image processing method for processing an image signal to an image output device, which performs gradation conversion of an image signal with a predetermined γ-LUT and outputs an image, wherein the signal value conversion process is performed on the image signal. Thus, a gradation conversion step for substantially converting gradation characteristics of an image output by the image output device is provided, and the gradation conversion step changes the gradation characteristics based on a predetermined lightness-transmission density characteristic. An image processing method characterized by converting. 4. An image processing method for processing an image signal to an image output device which performs gradation conversion of an image signal by a predetermined γ-LUT and outputs an image, wherein the signal value conversion process is performed on the image signal. Thus, the image output device is provided with a gradation conversion step for substantially converting gradation characteristics of the image output, in the gradation conversion step, the image output device reflects or transmits the image on a recording medium. An image characterized in that the density gradation characteristic in the case of outputting and the brightness gradation characteristic in the case of the image output apparatus outputting an image on a reflective recording medium are made substantially the same in a predetermined signal value range. Processing method. 5. The image processing method according to claim 3, wherein the transmission density-reflection density characteristic curve relating to the transmission density-reflection density characteristic is a downwardly convex curve. 6. An image feature amount extraction step of extracting an image feature amount representing an image feature, and an execution order determination step of determining an execution order of the gradation conversion and other image processing based on the image feature amount. The gradation conversion and the other image processing are executed according to the execution order determined by the execution order determining step. Image processing method. 7. The image processing method according to claim 6, wherein an image processing condition in the other image processing is changed according to the execution order. 8. The image processing method according to claim 6, wherein the other image processing includes any one of density adjustment processing, dynamic range compression processing, and frequency processing. . 9. The image processing method according to claim 1, wherein the image is a medical image. 10. An image processing apparatus including a gradation conversion step for substantially converting gradation characteristics of an image recorded on the image recording apparatus side by performing signal value conversion processing on the image signal. An image output method of receiving an image signal, performing gradation conversion according to a γ-LUT having an output density D (S) with respect to the original image signal S, and recording the image on a recording medium. When the converted image signal converted by the gradation conversion step is F (S), D (F
(S)) ≦ 1.5, the converted image signal difference value ΔFs = F (S + 1) −F (S) is 0.2F (Smax) / Smax ≦ | F (S + 1) −F (S)
| ≦ 5F (Smax) / Smax (where Smax is the maximum image signal value in the original image signal S and F (Smax) is the maximum image signal value in the converted image signal F (S)) An image output method comprising steps. 11. An image processing apparatus including a gradation conversion step for substantially converting gradation characteristics of an image displayed on the image display apparatus side by performing signal value conversion processing on the image signal. A γ-LU that receives an image signal and has an illuminance on the image display surface of L (S) with respect to the original image signal S
An image output method of performing gradation conversion according to T to display an image, wherein when the converted image signal after conversion by the gradation conversion step is F (S) with respect to the original image signal S, −log ₁₀
For S that satisfies (L (F (S)) / Lmax) ≦ 1.5, the converted image signal difference value ΔFs = F (S + 1) −F (S)
Is 0.2F (Smax) / Smax ≦ | F (S + 1) -F (S)
| ≦ 5F (Smax) / Smax, where Smax is the maximum image signal value in the original image signal S, F (Smax) is the maximum image signal value in the converted image signal F (S), and Lmax is the maximum illuminance. An image output method comprising the following image output step. 12. In the image output step, the signal difference value in the low density region is large and the signal difference value in the high density region is small, or the signal difference value in the high illuminance range is large and the signal difference value in the low illuminance range is large. Get smaller,
The image output method according to claim 10 or 11, characterized in that. 13. The image output method according to claim 10, wherein the image is a medical image. 14. An image output method for recording a medical image on a reflective recording medium, comprising: a background detection step of detecting a background area in the medical image, wherein the reflection density in the background area is 2.0 or less. An image output method, characterized by replacing with a signal of a region. 15. An image processing device for processing an image signal to an image output device for converting a gradation of an image signal by a predetermined γ-LUT to output an image, wherein the signal value conversion process is performed on the image signal. Accordingly, the image output device is provided with a gradation conversion unit that substantially converts the gradation characteristic of the image, and the gradation conversion unit is based on a predetermined transmission density-reflection density characteristic. An image processing apparatus, characterized by converting 16. An image processing apparatus for processing an image signal to an image output apparatus for converting a gradation of an image signal by a predetermined γ-LUT to output an image, wherein the signal value conversion processing is performed on the image signal. Thus, the image output device is provided with a gradation conversion unit that substantially converts gradation characteristics of the image, and the gradation conversion unit outputs the image onto the transparent recording medium by the image output device. Transmission density gradation characteristics in the case,
An image processing apparatus, characterized in that the reflection density gradation characteristics when the image output apparatus outputs an image on a reflection recording medium have substantially the same shape in a predetermined signal value range. 17. An image processing apparatus for processing an image signal to an image output apparatus, which performs gradation conversion of an image signal by a predetermined γ-LUT and outputs an image, wherein signal value conversion processing is performed on the image signal. Thus, the image output device is provided with a gradation conversion unit that substantially converts the gradation characteristic of the image, and the gradation conversion unit changes the gradation characteristic based on a predetermined lightness-transmission density characteristic. An image processing apparatus, characterized by converting. 18. An image processing apparatus for processing an image signal to an image output apparatus, which performs gradation conversion of an image signal with a predetermined γ-LUT and outputs an image, wherein signal value conversion processing is performed on the image signal. Thus, the image output device is provided with a gradation conversion unit that substantially converts the gradation characteristics of the image, and the gradation conversion unit is configured such that the image output device reflects or transmits the image on a recording medium. An image characterized in that the density gradation characteristic in the case of outputting and the brightness gradation characteristic in the case of the image output apparatus outputting an image on a reflective recording medium are made substantially the same in a predetermined signal value range. Processing equipment. 19. The transmission density-reflection density characteristic curve relating to the transmission density-reflection density characteristic is a downwardly convex curve.
The image processing apparatus according to claim 17, wherein: 20. Image feature amount extraction means for extracting an image feature amount representing an image feature, and execution order determination means for determining an execution order of the gradation conversion and other image processing based on the image feature amount. 20. The gradation conversion and the other image processing are executed in accordance with the execution order determined by the execution order determining means. Image processing device. 21. The image processing apparatus according to claim 20, wherein an image processing condition in the other image processing is changed according to the execution order. 22. The other image processing is density adjustment processing,
22. The image processing apparatus according to claim 20, further comprising a dynamic range compression process or a frequency process. 23. The image processing apparatus according to claim 15, wherein the image is a medical image. 24. An image processing apparatus having gradation conversion means for substantially converting gradation characteristics of an image recorded on the image recording apparatus side by subjecting the image signal to signal value conversion processing. An image output device that receives an image signal, performs gradation conversion according to a γ-LUT having an output density D (S) with respect to the original image signal S, and records an image on a recording medium. When the converted image signal converted by the gradation converting unit is F (S), D (F (S))
Image signal difference value ΔFs after conversion for S that satisfies ≦ 1.5
= F (S + 1) -F (S) is 0.2F (Smax) / Smax≤ | F (S + 1) -F (S)
| ≦ 5F (Smax) / Smax (where Smax is the maximum image signal value in the original image signal S and F (Smax) is the maximum image signal value in the converted image signal F (S)) Having means,
An image output device characterized by the above. 25. An image processing apparatus having gradation conversion means for substantially converting gradation characteristics of an image displayed on the image display apparatus side by subjecting the image signal to signal value conversion processing. An image output device that receives an image signal and performs gradation conversion according to a γ-LUT whose illuminance on the image display surface is L (S) with respect to the original image signal S, and displays the image with respect to the original image signal S. When the converted image signal after conversion by the gradation conversion means is F (S), -log ₁₀ (L
For S such that (F (S)) / Lmax) ≦ 1.5, the converted image signal difference value ΔFs = F (S + 1) −F (S) is 0.2F (Smax) / Smax ≦ | F (S + 1) -F (S)
| ≦ 5F (Smax) / Smax, where Smax is the maximum image signal value in the original image signal S, F (Smax) is the maximum image signal value in the converted image signal F (S), and Lmax is the maximum illuminance. An image output device having such image output means. 26. The image output means has a large signal difference value in a low density range and a small signal difference value in a high density range, or has a large signal difference value in a high illuminance range and a signal difference value in a low illuminance range. 26. The image output device according to claim 24 or 25, wherein the image output device becomes smaller. 27. The image output device according to claim 24, wherein the image is a medical image. 28. An image output device for recording a medical image on a reflective recording medium, comprising: background detection means for detecting a background area in the medical image, wherein the reflection density in the background area is 2.0 or less. An image output device, which is replaced with a signal of a region.