JPH0664528B2 - Image interface device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image interface device interposed between an image signal source and an image output device, and more specifically, it relates to a plurality of image signal sources having different γ characteristics. An image that converts an image signal output from the image signal source into an image signal that matches the γ characteristic of the image output device when a hard copy is obtained using a predetermined image output device according to the output image signal Regarding the interface device.

[Background of the Invention] For example, if a medical image diagnostic apparatus such as a CT scanner is used to reproduce a diseased part of a human body as image information, the condition of the affected part can be clearly grasped, which is very convenient for doctors and the like. In fact, in particular, by exposing and recording image information on a light-sensitive material and storing it as a hard copy, it can be used for medical diagnosis without being restricted by time and place. In this case, an image signal corresponding to the image information output from an image signal source such as a CT scanner is introduced into an image output device such as a laser printer, converted into exposure data, and then recorded on a photosensitive material. .

By the way, there is not always one type of medical image diagnostic apparatus such as a CT scanner which sends a signal to the image output apparatus, and various medical image diagnostic apparatuses such as an ultrasonic imaging apparatus and a nuclear magnetic resonance imaging apparatus are developed with the development of the medical diagnostic field. The device has been put to practical use. However, these medical image diagnostic apparatuses are usually designed to output an image to a CRT for diagnosis and convert a digital image signal into an analog video signal.

Therefore, when an image signal (analog video signal) is selectively sent from the medical image diagnostic apparatus to the image output apparatus to obtain a hard copy, the digital image signal in the medical image diagnostic apparatus is converted into an analog video signal. There is a possibility that the conversion characteristic (γ characteristic) and the γ characteristic of the image output device may not match, and eventually, even if such an image is exposed and recorded on the photosensitive material, the image itself reproduced as a hard copy is unclear. As a result, there is an inconvenience that it cannot be used for accurate medical diagnosis.

Furthermore, the medical image diagnostic apparatus has different γ characteristics for each apparatus.

In order to improve this, it is possible to install a plurality of image output devices having a γ characteristic suitable for the medical image diagnostic device, but this is not economical and a large installation space must be secured. There is a difficulty in adopting it because it must be done.

Further, as another improvement method, it is possible to adjust the γ characteristic in the image output device each time according to a predetermined medical image diagnostic device, but normally, this adjustment work is extremely specialized and complicated and a long adjustment. The time required exposes the drawback of not being able to meet the basic requirements of the medical field, which favor the rapid execution of diagnoses.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned technical problem, and hard copies image signals output from a plurality of image signal sources having different γ characteristics by a predetermined image output device. When outputting as, a γ correction characteristic corresponding to each image signal source is stored in advance, the γ characteristic of the image signal output from the image signal source is corrected by the γ correction characteristic, and then a predetermined image signal By converting the image signal into the image output device, the corrected image signal is introduced into the image output device.
An object of the present invention is to provide an image interface device capable of promptly obtaining a high-quality hard copy in accordance with video signals output from a plurality of image signal sources by using only one image output device. .

[Means for Achieving the Object] In order to achieve the above object, the present invention outputs a hard copy based on a plurality of image signal sources having different γ characteristics and an image signal output from the image signal source. An image interface device interposed between an image output device, for converting the image signals respectively output from the plurality of image signal sources so as to correspond to the γ characteristic of the image output device,
It is characterized by comprising a plurality of γ correction tables for each image signal source.

Further, the present invention is characterized by including at least one density coefficient table that substantially changes at least the maximum density and the contrast among the γ characteristics of the image output apparatus.

[Embodiment] Next, a preferred embodiment of the image interface apparatus according to the present invention in relation to a medical image recording system to which the image interface apparatus is applied will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a medical image recording system, and the medical image recording system 10 basically comprises four types of image signal sources 12a to 12d such as a CT scanner and an image interface device according to the main part of the present invention. 14 and an image output device 16 such as a laser printer. The video signals S _{a to} S _d and the control signals D _{a to} D _d output from the image signal sources 12a to 12d are introduced into the A / D converter 22 and the communication interface 24 via the electronic switches 18 and 20, respectively. To be done. In this case, the electronic switches 18 and 20 are interlock switches of the one-circuit, four-contact type, and include the contacts 19a to 19d and the contact 21a.
To 21d and common contacts 19e, 21e.

The output image data after A / D conversion by the A / D converter 22 is recorded in the frame memory 26 for each screen, and the digital image data S ₂ output from the frame memory 26 is a look for performing γ correction of the image. The digital image data S ₄ is converted and introduced into the input terminal of the output interface unit 30 via the up table setting unit 28. In this case, the look-up table setting unit 28 is set with a γ correction table created by the control unit 44 and the look-up table creating unit 32, as described later. This γ correction table is
As will be described later, the control information introduced from the communication interface 24 and the external storage device 34 such as a floppy disk are supplied, and the γ correction table memory 36 and the density coefficient table memory 38 are set and recorded in the device table memory 40. It is created based on the data and the input data input by the operator such as a doctor using the operation panel 42. Here, the operation panel 42 constituting the image interface device 14 is usually attached to the image signal source 12a side and used for inputting data to the image interface device 14 by a remote control method, as shown in the figure.

Therefore, the content of the digital image data S ₂ output from the frame memory 26 is converted into digital image data S ₄ by the look-up table setting unit 28, and the digital image data S ₄ is output as a signal via the output interface unit 30. It is introduced into the image output device 16 as S ₆ . Then, the hard copy HP is output based on the signal S ₆ introduced in the image output device 16.

The medical image recording system incorporating the image interface apparatus according to the present embodiment is basically constructed as described above, and its operation and effect will be described below. In order to facilitate understanding of the present invention, an embodiment in which only the γ correction table is used will be described in order to facilitate understanding of the present invention, and secondly, both the γ correction table and the density coefficient table are used. Embodiments that do will be described.

Therefore, first, an embodiment using only the γ correction table will be described. Usually, the doctor or the technician confirms the state of the affected part by _one of the image signal sources 12a to 12d, for example, the image PCR ₁ displayed on the CRT 13 of the image signal source 12a. Then, when trying to obtain a hard copy HP from the image output device 16 for the image PCR ₁ corresponding to the affected area displayed on the CRT 13, the hard copy H
Operation panel for specifying the image signal source from which P should be acquired
The identification number N _d corresponding to the image signal source 12 a is input from 42. In this case, the specific code of the identification number N _d is, for example,
It is assumed that the image signal source 12a has a suffix n such as a reference numeral 12an.

The control unit 44 refers to the device table memory 40 based on the identification number N _d input from the operation panel 42. The device table memory 40, as shown in FIG.
The identification number N _d corresponding to 2d and the image signal sources 12a to 12d
Γ correction table number N _r = 100a applied γ correction table number N _r is stored, the control unit 44 corresponding to the identification number N _d = 12AN from the device table memory 40 with respect to
Read n. In this case, γ correction table number N _r = 100a
The γ correction tables 100a to 100d corresponding to n to 100dn are
Usually, it is stored in an external storage device 34 such as a floppy disk, and these γ correction tables 100a to 100d are stored in a γ correction table memory 36 in the image interface device 14.

The γ correction tables 100a to 100d stored in the γ correction table memory 36, as will be described later, change the γ characteristics of the image signal sources 12a to 12d connected to the image interface device 14 into the γ characteristics of the image output device 16. It is a table that is converted to match. For example, the γ characteristic of the image output device 16 is
As shown in FIG. 3A, the image density PD ₁₆ on the hard copy HP is determined in accordance with the level of the signal S ₆ input thereto, which is a linear γ characteristic 110, while the image signal source 12a Γ characteristic 100ai for faithfully reproducing the image PCR ₁ displayed on the CRT 13 on the hard copy HP (hereinafter,
The ideal γ characteristic) is the γ characteristic as shown in FIG. 3b.

In this case, the γ characteristic 100ax when the γ correction is not performed in the look-up table setting unit 28, that is, when the signal S ₆ which is substantially the same as the video signal S _a is input to the image output device 16 is shown in FIG. The γ characteristic as shown in ((hereinafter, referred to as uncorrected γ characteristic) becomes a characteristic deviating from the ideal γ characteristic 100ai. The reason for such a deviated characteristic is that the image PCR ₁ on the CRT 13 as the display means has a characteristic that the brightness of the image is determined by a signal (in this case, the video signal S _a ) in _a ramp function. Hard copy H
The image PCR ₂ formed on P is due to the fact that the density of the image is determined by a signal in a logarithmic function.

Therefore, a γ correction table for converting the video signal S _a output from the image signal source 12a so as to match the ideal γ characteristic 100ai is required. This γ correction table is created from the ideal γ characteristic 100ai and the uncorrected γ characteristic 100ax as a γ correction table 100a represented by a characteristic curve as shown in FIG. 3d. To describe a specific creating method, for example, in the ideal γ characteristic 100ai, the image density PD ₁₆ corresponding to the video signal S _a = 0.5 is PD ₁₆ = 0.3, but the uncorrected γ characteristic 100
In ax, the image density P corresponding to the video signal S _a = 0.5
D ₁₆ becomes PD ₁₆ = 0.6 and does not match. Therefore, since S _a = 0.25 is obtained as the value of the video signal S _a corresponding to the image density PD ₁₆ = 0.3 on the uncorrected γ characteristic 100ax, the γ correction table 100a is used for the digital image data S ₂ =
It will be appreciated that the value of 0.5 should be created so that it can be converted into the value of digital image data S ₄ = 0.25.

Similarly, the video signal S output corresponding to the characteristic of the display means (not shown) peculiar to the image signal sources 12b to 12d.
_b to create a γ correction table 100b to 100d to be applied to S _d, recorded in advance these γ correction tables 100a to 100d including the γ correction table 100a in the external storage device 34.

Note that the γ characteristic 110 for the image output device 16 described above,
Ideal γ characteristic 100ai, uncorrected γ characteristic 100ax and image signal source
The scales on the coordinate axes of FIGS. 3a to 3d representing the γ correction table 100a applied to 12a are shown in order to facilitate the understanding of the present invention, the image density PD ₁₆ , the video signal S _a and the digital image data S ₂ , S ₄ are represented by so-called normalized levels, which are divided by the respective maximum level values.

By the way, as described above, the image signal source
The identification number N _d = 12an corresponding to 12a is input from the operation panel 42 to the control unit 44. The control unit 44 refers to the device table memory 40 based on the identification number N _d = 12an input from the operation panel 42, and searches the γ correction table 100a corresponding to the γ correction table number N _r = 100an by the lookup table setting unit 28.
Set to. As described above, when only the γ correction table is used, the lookup table creation unit 32 does not perform any special processing on the γ correction table and the γ correction is performed by the lookup table setting unit 28 with the data content as it is. The table is set as a lookup table.

Then, the control unit 44 connects the common contacts 19e and 21e of the electronic switches 18 and 20 to the settings 19a and 21a corresponding to the image signal source 12a, respectively, based on the identification number N _d = 12an. Then, the communication interface 24, the common contact 21e and the contact 21a
The video signal S _a is received from the image signal source 12a via the.
The image signal source 12a for transmitting the video signal S _a transmits the control signal D _a including information indicating that the image PCR ₁ to be transmitted to the image interface device 14 in parallel with this, to the contact 21a, the common contact 21e and the common contact 21e. It is sent to the control unit 44 via the communication interface 24. The identification number N _d may be input by an annual operation using the operation panel 42 as described above, but separately from this, for example,
When it is planned to use the image signal source 12a in advance, a power-on reset function is added to the image interface device 14 and the identification number N _{d of the} device table memory 40 is added.
It is needless to say that a default value of N _d = 12an can be set to automatically input the control signal D _a from the image signal source 12a without operating the operation panel 42.

In the state where the handshake communication is completed, the video signal S _a output from the image signal source 12a is transferred to the A / D converter via the contact 19a and the common contact 19e in the electronic switch 18.
The image data is introduced into the frame 22 and recorded as digital image data in the frame memory 26 for each screen. As described above, by using the look-up table set in the look-up table setting unit 28 for the digital image data S ₂ recorded in the frame memory 26, in this case, the γ correction table 100a shown in FIG. After being converted into digital image data S ₄ according to the γ characteristic 110 of 16, the signal is introduced into the image output device 16 as a signal S ₆ via the output interface section 30. Here, the digital image data S ₂ introduced into the look-up table setting unit 28 is a signal which is substantially the same as the video signal S _a introduced into the image interface device 14, and is introduced into the image output device 16. The signal S ₆ and the digital image data S ₄ are substantially the same signal.
Therefore, it will be understood from the above that the horizontal and vertical scales of the γ correction table 100a shown in FIG. 3D may be digital image data S _{2 and} digital image data S ₄ , respectively.

By interposing the image interface device 14 according to the present invention between the image signal source 12a and the image output device 16, the image PCR ₁ displayed on the CRT 13 constituting the image signal source 12a is displayed on the image output device 16 It can be faithfully reproduced as an image PCR ₂ on the hard copy HP output from the.

Although the above description is for the γ correction for the video signal S _a output from the image signal source 12a, another image signal source 12b is used.
To 12d output video signals S _{b to} S _d using the device table memory 40.
It is easily understood that by setting the remaining γ correction tables 100b to 100d in 28, proper γ correction can be performed and a predetermined hard copy HP can be obtained, and a detailed description thereof will be omitted.

Next, a second embodiment using both the γ correction table and the density coefficient table will be described. In the following description, the contents overlapping with the description of the first embodiment will be briefly described.

Generally, in a medical diagnostic apparatus, the γ characteristic of the apparatus is determined by the three characteristics of the characteristics of the signal source such as X-rays and ultrasonic waves, the characteristics of the imaging device, and the display means such as CRT. Depending on the characteristics, the level of the video signal output may be biased depending on the diagnostic region, for example, the imaging region of each of the brain, lungs, heart, and the like. In this case,
If the video signal is faithfully reproduced as it is, that is, if it is reproduced only by the γ correction table and then reproduced by the image output device 16, an image with extremely low contrast is obtained, and it may not be appropriate to execute the diagnosis of the affected area as it is. Occur. In such a case, it is necessary to calculate new γ correction tables 105a to 105d (hereinafter, referred to as a new γ correction table) from the γ correction tables 100a to 100d and a density coefficient table to be described later, and set this as a lookup table. Occurs.

As shown in FIG. 4, the density coefficient table 114 has a maximum density D among the γ correction tables 100a to 100d corresponding to a plurality of density coefficient table numbers N _q = CD _{0 to} CD _n.
maxn (n = 0 to n), contrast C _n (n = 0 to n) and negative / positive conversion coefficient E _x (x =
0 or 1) is a preset table. Here, the negative / positive conversion corresponds to the value of the coefficient E ₀ or the coefficient E ₁ of the negative / positive conversion coefficient E _x , and the conversion of the image PCR _{1 from} the positive image to the negative image or from the negative image to the positive image. A conversion that executes the conversion of.

Therefore, a doctor or the like uses the operation panel 42 to specify a predetermined identification number N _d.
, The identification number N _d = 12 for the image signal source 12a
Select an, and the density coefficient table number N _q = CD _{0 to} CD
_It is assumed that N _q = CD ₀ is selected in _n . in this case,
The control unit 44 controls the identification number N _{d and the} concentration coefficient table number N _q.
Based on the above, as described above, the electronic switches 18 and 20 are connected in a predetermined contact positional relationship, and the data related to the γ correction table 100a supplied from the external storage device 34 and stored in the γ correction table memory 36 is searched. Introduced in the up table creating section 32. Further, under the control of the control unit 44, the lookup table creating unit 32 is provided with the density coefficient table 11
Among the four, the data relating to the maximum density D _maxn = D _max0 corresponding to the density table number N _q = CD ₀ and the contrast C _n = C ₀
Data related to

Therefore, the look-up table creating unit 32 first creates a γ correction table 102a in which the contrast of the γ correction table 100a is converted as shown in FIG. 5A, and then, as shown in FIG. The new γ correction table 105a is created by converting the maximum density of the γ correction table 102a whose contrast has been converted. Specifically, the γ correction table 10
When the function S _{4 of} 0a is represented by S ₄ = f (S ₂ ), the value of the contrast C _n = C ₀ is a natural number, and the γ correction table 102a in which the contrast is converted has the function S ₄ = C ₀ · f ( S ₂ )
On the other hand, the new γ correction table 105a has the maximum density D
_maxn = D is a natural number values of _max0 digital image data S ₄
If the concentration when = 1 is D _MAX , the function S ₄ is It is represented by. Mostly, in this embodiment, the maximum concentration D
The value of _{the MAX} function S ₄ so are normalized to D _MAX = 1 is expressed as _{S 4 = D max0 · C 0} · f (S 2). Then, the new γ correction table 105a is set in the lookup table setting unit 28 as a new lookup table.

In this case, the new γ correction table 105a set in the lookup table setting unit 28 converts the digital image data S ₂ corresponding to the video signal S _a output from the image signal source 12a into the digital image data S ₄ . After that, it is converted into a signal S ₆ via the output interface unit 30 and output from the image output device 16 as a hard copy HP.

In this case, the image PCR ₂ on the hard copy HP newly converted and newly created by the new γ correction table 105a has a narrow range of the digital image data S ₂ as can be understood from the characteristic curves of FIGS. , In other words, the video signal S _a
It will be appreciated that the narrow range of can be gradation converted into a relatively multi-tone image. Further, as shown in FIG. 5b, it is usually the image PCR ₁ on the display means of the image signal source that lowers the maximum density to limit the so-called high density area.
Since the number of pixels forming the image is smaller than the number of pixels forming the image PCR ₂ on the hard copy HP output from the image output device 16, reproduction with the same value increases the gradation difference in density between pixels. On the contrary, the image may be difficult to see, and in such a case, by limiting the maximum value of the densities and reducing the density difference between the pixels, it is possible to obtain an easy-to-see image that gives a soft impression.

As described above, by using the density coefficient table 114, it is possible to variously change the gradation expression of the output image. Therefore, the gradation conversion should be performed so that the optimum reproduced image can be obtained according to the diagnosis region. Can be done. The above description is the description of the second embodiment in which the lookup table is created using the γ correction table and the density coefficient table.

Although the video signal is handled as an analog video signal in the above embodiment, it is needless to say that the video signal may be a digital video signal. In this case, the digital video signal is input interface section (not shown). It will be easily understood that the structure may be directly introduced into the frame memory 26 via (1).

Further, the conversion of the contrast of the image signal is not limited to the method of converting the slope of the function using the maximum value of the image signal as a fixed point as shown in FIG.
Needless to say, a method of converting the slope of the function with the value of 1/2 as a fixed point may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, image signals output from a plurality of image signal sources having different γ characteristics are converted by the image interface device into signals that match the γ characteristics of a predetermined image output device. Converting. Therefore, by interposing the image interface device according to the present invention between a plurality of image signal sources and only one image output device, it is possible to quickly respond to all image signals output from the plurality of image signal sources. You can get a hard copy. Moreover, since it is possible to artificially change the γ characteristic of the image output device using the density coefficient table, it is possible to easily change the gradation expression of the image carried on the output hard copy. The image density can be converted into the image density that is most visible to the doctor for the diagnosed part of the affected part.

Although the present invention has been described with reference to the preferred embodiment, the present invention is not limited to this embodiment,
Needless to say, various improvements and design changes can be made without departing from the scope of the present invention, for example, by configuring the image output device and the image interface device to be integrated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a medical image recording system incorporating an image interface device according to the present invention, and FIG. 2 is an explanatory diagram of a device table stored in a device table memory in the image interface device shown in FIG. FIGS. 3a to 3d are explanatory views for creating a γ correction table stored in the γ correction table memory in the apparatus, and FIG. 4 is a density coefficient stored in the density coefficient table memory in the apparatus. FIGS. 5A and 5B are explanatory diagrams of the table, and FIGS. 5A and 5B are explanatory diagrams when the γ correction table is converted by the density coefficient table shown in FIG. 4. 10 ... medical image recording system 12 a to 12 d ... image signal source 14 ... image interface device 16 ... image output device 100a ... gamma correction table 100Ai ... ideal gamma characteristics 100ax ... uncorrected gamma characteristics 110 ... gamma characteristic D _a to D _d ... control signal S _a to S _d ... video signal S _2, S ₄ ... digital image data S ₆ ... signal

Claims (2)

[Claims] 1. An image interface device interposed between a plurality of image signal sources having different γ characteristics and an image output device for outputting a hard copy based on an image signal output from the image signal source. In order to convert the image signals respectively output from the plurality of image signal sources so as to correspond to the γ characteristic of the image output device,
An image interface device comprising a plurality of γ correction tables for each image signal source. 2. The image interface apparatus according to claim 1, further comprising one or more density coefficient tables that substantially change at least the maximum density and contrast among the γ characteristics of the image output apparatus. .