JP2618942B2 - Hard copy device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a CT scan or a magnetic resonance imaging apparatus (MR).
A video signal of a diagnostic image obtained from a medical image diagnostic apparatus such as I) is input to a multi-format camera as a CRT imager, and an image displayed on a CRT display inside the imager is formed on a film surface through an optical system. The present invention relates to a hard copy device that obtains an image for hard copy by engraving.

(Prior art) In medical image diagnostic apparatuses such as CT scan and MRI,
There is a CRT monitor on the main unit side, and diagnostic images are displayed here. By inputting the video signal entering the CRT monitor to a multi-format camera which is a CRT imager,
There is provided a hard copy device for displaying an inverted image of the exact same image on a CRT display inside the imager and forming an image on a film surface by an optical system to obtain a hard copy image.

By the way, in such a conventional hard copy apparatus, in order to perform initial setting so that the gradation characteristic of the CRT display matches the ideal gradation characteristic curve of the film, it is necessary to actually photograph on the film surface by using the CRT. The brightness and contrast of the display were adjusted by trial and error based on experience and some intuition.

In this case, it is possible to grasp how the gradation characteristic of the CRT display changes depending on brightness, contrast, and photographing time. That is, by adjusting the brightness of the CRT display, the change in the gradation due to the brightness of the hard copy characteristic curve moves in parallel with a constant slope as shown in FIG. In FIG. 4, the X-axis is the logarithm of the amount of light, which is represented as 16 levels for convenience. When the contrast of the CRT display is changed, it can be seen that the inclination changes around a certain density as shown in FIG. In FIG. 5, the inclination changes around the density of 1.0.

(Problems to be solved by the invention) However, it is understood how the characteristic curve of the hard copy changes by adjusting the brightness and contrast of such a CRT display or changing the photographing time. Even if it is possible, the characteristic curve of the hard copy may vary depending on the effect of the concentration of the developing solution in the automatic developing device or the use of the automatic developing device and the film at the installation location when the apparatus is moved. Therefore, it has been difficult to immediately adjust the gradation characteristic of the CRT display to the condition of the gradation characteristic curve of the film that is ideal.

According to the present invention, density difference information is obtained from a tone characteristic curve of a hard copy at a certain point in time and an ideal film tone characteristic curve, and brightness and contrast for controlling a CRT display are determined based on the density difference information. It is an object of the present invention to provide a hard copy device that can set a gradation characteristic of a CRT display to an ideal film characteristic curve by correcting the characteristic.

[Configuration of the Invention] (Means for Solving the Problems) According to the present invention, a hard copy gradation characteristic represented by a gradation level versus a density value has a constant gradient according to a brightness change amount of a CRT display. In a hard copy device based on a hard copy gradation characteristic curve that rotates in parallel with the density value at the first gradation level according to the contrast change amount of the CRT display while maintaining the parallel movement, the ideal gradation characteristic curve Brightness change amount input means for inputting a density difference between the CRT display and the hard copy gradation characteristic curve at the first gradation level, and determining a brightness change amount of the CRT display so that the density difference becomes zero. And the second of the ideal gradation characteristic curve and the hard copy gradation characteristic curve.
A density difference at the gray level of the CRT display, and a normalization means for normalizing the density difference, and a contrast change amount of the CRT display determined so that the density difference normalized by the normalization means becomes zero. Brightness change amount determining means for controlling the brightness of the CRT display according to the brightness change amount determined by the brightness change amount determining means; and the contrast change amount determined by the contrast change amount determining means. And a contrast control means for controlling the contrast of the CRT display according to the amount.

(Operation) Therefore, in a hard copy device having such a configuration,
First, the density difference at the first gradation level between the ideal gradation characteristic curve and the hard copy gradation characteristic curve is input, and the brightness change amount of the CRT display is determined so that the density difference becomes zero. Is done. Further, a density difference between the ideal gradation characteristic curve and the hard copy gradation characteristic curve at the second gradation level is input, and this density difference is normalized, and the normally changed density difference becomes zero. CRT to be
The contrast change amount of the display is determined. Then, the brightness and contrast of the CRT display are controlled according to the determined brightness change amount and contrast change amount. Thus, a hard copy gradation characteristic equivalent to an ideal gradation characteristic curve can be easily obtained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration example of a hard copy apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a brightness change amount conversion unit, and the change amount conversion unit 1 includes a density value at a first measurement point of an ideal gradation characteristic curve of a film;
A density difference signal Δd _{1 from} the density value at the first measurement point of the hard copy gradation characteristic curve at a certain time is input. The ideal gradation characteristic curve of the film is arbitrarily set by the operator. Reference numeral 2 denotes a brightness control unit that corrects brightness for controlling the CRT display 3 according to the change amount input from the brightness change amount conversion unit 1. Reference numeral 4 denotes a density difference normalizing unit. The density difference normalizing unit 4 includes a density value at a second measurement point of a tone characteristic curve ideal for a film and a hard copy tone characteristic curve at a certain time. The density difference signal Δd _{2 from} the density value at the second measurement point and the change amount from the brightness change amount conversion unit 1 are input, and the brightness control unit 2 outputs the change amount output from the brightness change amount conversion unit 1. This is converted into a density difference signal Δd ₃ when the brightness is corrected accordingly.
Reference numeral 5 denotes a contrast change amount conversion unit to which the density difference signal Δd ₃ from the density difference normalization unit 4 is input. The change amount conversion unit 5 outputs a change amount according to the density difference signal Δd _3. is there. Reference numeral 6 denotes a contrast control unit that corrects brightness for controlling the CRT display 3 in accordance with the change amount input from the change amount conversion unit 5. In the figure, reference numeral 7 denotes a film on which the inverted image displayed on the CRT display 3 is formed through a lens 8 as an optical system.

FIG. 2 is a block diagram showing an example of the internal configuration of the brightness control unit 2, which comprises a pulse generator 2a, an up / down counter 2b, a digital /
It is composed of an analog converter 2c. Pulse generator 2a
When a change amount (a digital value whose change amount per numerical value is design-established by design) is input from the brightness change amount conversion unit 1, the pulse amount corresponding to the value is changed to a positive value. Is output as an up clock signal, and in the case of negative, it is output as a down clock signal. The up / down counter 2b changes the contents of the counter when an up clock or a down clock signal is input from the pulse generator 2a, and the digital / analog converter 2c outputs from the up / down counter 2b. The analog signal is converted into an analog signal corresponding to the count value, and is output as a brightness control signal.

FIG. 2 shows the internal configuration of the brightness control unit 2, but the contrast control unit 4 has the same internal configuration as this, and a description thereof will be omitted here.

Next, the operation of the hard copy apparatus configured as described above will be described with reference to the gradation characteristic curve of hard copy shown in FIG. Here, in FIG. 3, A is an ideal characteristic curve, B is a characteristic curve at a certain point in time, and C is an ideal characteristic curve on the basis of a gradation level 9 with a density value of 1.0 as a center. The characteristic curves in the case where the brightness has been adjusted are shown.

Now, the brightness change amount conversion unit 1 supplies the gradation level 9
Density difference between the density difference [Delta] d ₁ between the characteristic curve A characteristic curve B at the phrase time, a characteristic curve B in the ideal that the characteristic curve A phrase time when the gradient level 12 to the ideal case of Δd ₂
Are respectively measured, and the density difference signal Δd ₁ is input to the brightness change amount converter 1 and the density difference signal Δd ₂ is input to the density difference normalizer 4. The brightness change amount conversion unit 1 inputs a change amount corresponding to the density difference signal Δd ₁ as a digital value to the brightness control unit 2 and the density difference normalization unit 4. When the change amount from the brightness change amount conversion unit 1 is input to the pulse generator 2a shown in FIG. 2, the brightness control unit 2 determines whether the change amount is positive or negative by an up or down clock signal. Is output according to the value. Here, since the amount of change corresponding to the density difference signal [Delta] d ₁ becomes negative, down clock signal is input to the up / down counter 2b. Therefore, this up /
The down counter 2b changes the count value in the down direction and inputs the output to the digital / analog converter 2c. When the output of the digital / analog converter 2c to the up / down counter 2b is added, which converts an analog signal corresponding to the density difference signal [Delta] d _1, controls the brightness of the CRT display 4. As a result, the characteristic curve B at a certain point in time shown in FIG. 3 becomes a characteristic curve C translated in parallel to a point passing through the gradation level 9 of the ideal characteristic curve A.

On the other hand, when the above-described density difference signal Δd ₂ and the change amount from the brightness change amount conversion unit 1 are input to the density difference normalization unit 4, the density difference normalization unit 4 sets the density when the brightness is adjusted. The difference, that is, a density difference signal Δd ₃ between the ideal characteristic curve A at the gradation level 12 and the characteristic curve C shifted in parallel, and converts this into a contrast change amount conversion unit 5
To enter. When a change amount according to the density difference signal Δd ₃ is input to the contrast change amount conversion unit 5, the contrast control unit 5 has a pulse generator and an up / down switch. From the digital / analog converter through the counter, the density difference signal Δd ₃
Is output as a contrast control signal of the CRT display 4. As a result, the characteristic curve C shown in FIG. 3 is equivalent to turning around a point passing through the gradation level 9 of the ideal characteristic curve A so as to overlap the ideal characteristic curve A, and the CRT It is possible to set the gradation characteristic of the display 4 to a characteristic curve of a film that is ideal.

As described above, in the present embodiment, in the gradation characteristic curve of the hard copy shown in FIG. 3, an ideal characteristic curve A and a characteristic curve B measured using the gradation level 9 of the density value 1.0 as the first measurement point. The brightness difference signal Δd ₁ is given to the brightness change amount conversion unit 1 to obtain the change amount, and the change amount is added to the brightness control unit 2, so that the brightness of the CRT display 4 is adjusted to a signal level corresponding to the density difference signal Δd _1. And a density difference signal Δd between an ideal characteristic curve A and a characteristic curve B measured using the gradation level 12 as a second measurement point.
₂ , the change amount from the brightness change amount conversion unit 1 is given to the density difference normalization unit 4, and a density difference signal Δd ₃ between the ideal characteristic curve A and the characteristic curve C when the brightness is adjusted is obtained. Is given to the contrast control unit 6 by the change amount converted by the contrast change amount
Since the contrast of the display 4 is adjusted to a signal level corresponding to the density difference signal Δd ₃ , it is possible to set the gradation characteristic of the CRT display 4 to a characteristic curve of a target film. Therefore, it is not necessary to adjust the gradation characteristics of the hard copy to an ideal one by actually photographing the film based on experience or some kind of intuition as in the conventional case. It is possible to easily and easily set the ideal gradation characteristics of the film having the tonal characteristics in a short time.

In the above-described embodiment, the hard copy in the case where the density value is centered on 1.0 in the gradation characteristic curve shown in FIG. 3 has been described. It is not limited to the density value. As the brightness changing amount conversion unit 1 which converts the amount of change density difference signal [Delta] d ₁ may be used an arithmetic circuit for calculating a change amount for each of the density difference signal [Delta] d ₁ is input and advance a plurality of density difference A table in which the change amount corresponding to the signal is written may be prepared, and a memory configured to read the change amount corresponding to the density difference signal at that time from the table may be used.

[Effects of the Invention] As described above, according to the present invention, density difference information is obtained from a tone characteristic curve of a hard copy at a certain point in time and a tone characteristic curve of an ideal film, and this density difference information is obtained. Originally CR
Since the brightness and contrast for controlling the T display are corrected, it is possible to provide a hard copy device that can easily set the gradation characteristic of the CRT display to the characteristic curve of a film that is ideal.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a hard copy apparatus according to the present invention, FIG. 2 is a block diagram showing an internal configuration of a brightness control unit in the embodiment, and FIG. 3 explains the operation of the embodiment. Curve characteristics curve diagram of hard copy for performing CRT display, FIG. 4 is a gradation characteristic curve diagram when the brightness of the CRT display is changed, and FIG. 5 is a gray scale when the contrast of the CRT display is changed. It is a characteristic curve figure. 1 ... Brightness change amount conversion unit, 2 ... Brightness control unit, 3 ... CRT display, 4 ... Dense difference normalization unit, 5
...... Contrast change amount converter, 6 ... Contrast controller.

Claims (1)

(57) [Claims] A hard copy gradation characteristic represented by a gradation level versus a density value is translated in parallel with a constant gradient according to the brightness change amount of a CRT display, and the contrast change amount of the CRT display is changed. A hard copy device based on a hard copy gradation characteristic curve rotating around a density value at a first gradation level, wherein the ideal gradation characteristic curve and the hard copy gradation characteristic curve Brightness change amount determining means for determining a brightness change amount of the CRT display so that the density difference becomes zero, the ideal tone characteristic curve and the hard copy A density difference between the tone characteristic curve and the second tone level, and a normalizing means for normalizing the density difference; and a density difference normalized by the normalizing means becomes zero. Contrast change amount determining means for determining the contrast change amount of the CRT display, and brightness control means for controlling the brightness of the CRT display according to the brightness change amount determined by the brightness change amount determining means, A hard copy device comprising: a contrast control unit that controls the contrast of the CRT display according to the contrast change amount determined by the contrast change amount determination unit.