JPS6124708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for sharpening reproductions of continuous tone originals comprising an electro-optical scanning device for the original, a device for deriving a sharpening signal, and a device for superimposing the sharpening signal on the image signal. The present invention relates to a device for controlling temperature.

It is known to affix a single color or multicolor continuous tone original image as a transparent or opaque image to a scanning drum and photoelectrically scan it. Scanning then takes place as follows: the scanning beam is imaged to a point on the original, and the original is scanned in a spiral by means of the rotational movement of the scanning drum and the movement of the scanning beam in the direction of the drum axis. In the case of multiple printing, the reflected or transmitted light reflected from the original image is separated into spectral regions of the three primary colors cyan, magenta, and yellow by a dichroic filter, and converted into electrical signals by a photoelectric conversion device.
This electrical signal is a so-called primary color signal. These primary color signals then control a recording section, such as an engraving needle or a recording lamp, and each primary color signal is then reproduced onto a record carrier fixed on a recording drum. The operation of the recording drum and the recording section are synchronized with the operation of the scanning drum and scanning beam. That is, the recording drum and scanning drum rotate at the same speed. The recording speed may be faster or slower than the scanning speed depending on the desired magnification or reduction of the copy. The relative axial movement between scanning part and recording part, ie scanning part and record carrier, also takes place.

Because the printing ink is imperfect and factors other than the printing ink affect the final copy color throughout the copying process, in order to obtain the desired color by copying, it is difficult to obtain the desired color from the photoelectric conversion device until it reaches the recording section. The primary color signals often have to be electronically controlled once or several times in the process. In this case, for example, gradation changes, undercolor removal, and color corrections are generally performed under electronic control.

In many cases, the original image to be scanned is a photographic image in which part of the sharpness of the original image has been reduced due to film development, enlargement, or copying. must be restored to. Therefore, the second color signal other than the primary color signal is
image signal is used, and this image signal is superimposed on the primary color signal to restore sharpness. This image signal is named a sharpening signal.

This sharpening signal can be obtained, for example, by the following two methods. In the first method, the image signal obtained by scanning the original image, that is, the primary color signal, is differentiated once or several times, and the resulting sharpening signal is extracted from the primary color signal. The sharpening signal is then superimposed on the primary color signal. As a result, the primary color signals are sharpened and further processed according to the process described above.

In a second method, corresponding to the blur masking in photocopying technology, in addition to the sharp scanning points, the vicinity of the so-called scanning points is additionally scanned. The resulting signal represents the average brightness in the vicinity of this scan point and is subtracted from the primary color signal. The signal obtained as a result of the subtraction is used as a sharpening signal and superimposed on the image signal. A sharpened signal results, which is further processed in a corresponding manner.

Both of the above methods have the advantage that the reduced sharpness is restored, but relatively sharp parts of the original may be reproduced even sharper, resulting in too high a sharpness. However, if the sharpness is then lowered again, extremely detailed parts of the original image, such as textiles or patterns, will be reproduced indistinctly.

SUMMARY OF THE INVENTION It is an object of the present invention to relate to an apparatus for photoelectric copying of continuous tone originals, which overcomes the above-mentioned drawbacks and allows each part of the original to be sharpened independently.

According to the present invention, this problem is solved as follows. That is, a mask device having a partial mask is provided, and the superimposing device is provided with means for increasing or reducing a sharpening signal superimposed on the image signal using a signal obtained by scanning the partial mask. That's what I do.

It is known to choose the amplitude of a sharpening signal to be constant over the entire original image and to superimpose this sharpening signal on the image signal. However, in that case, it is impossible to locally change the sharpness of the original image. According to the invention, the sharpening signal is controlled by a mask signal. In that case, the mask signal is obtained by scanning a mask formed from the original image content in synchronization with the original image. The superimposition device can be configured as a switch, for example.

Next, the present invention will be explained with reference to the drawings.

In FIG. 1, the surface of the scanning drum is transparent for recording transparencies, such as transparencies 2, for example. A mask 4 and a record carrier 5 are fixed to the drum 3. The drums 1 and 3 are driven by an electric motor 7 via a shaft 6. The scanning units 9 and 10 and the recording unit 11 are also driven by the electric motor 7 via the feed screw 8. The scanning unit 9 scans the transparency 2,
The scanning unit 10 scans the mask 4. The recording unit 11 is arranged corresponding to the record carrier 5. The scanning light beam 15 enters the interior of the scanning drum 1 from the light source 12 via the lens system 13 and 14 and through the hole 16 of the mirror 17. A mirror 18 is provided inside the scanning drum 1. The light ray 15 is imaged by this mirror 19 at an image point 19 on the transparency 2. Light source 12, lens 13
and 14, the mirror 18 is arranged such that the scanning beam 15 is imaged at an image point 19 of the transparency 2.
When the scanning light beam 15 passes through the transparency 2, it reaches an image point 19.
is modulated by the content of the original image, passes through a lens 20 in the scanning section 9, passes through the hole 21 in the mirror 22, and reaches the color separation section. This color separation section is composed of dichroic filters 23 and 24 and photoelectric conversion devices 25, 26 and 27. The scanning beam 15 consists of three partial beams, namely partial beams belonging to each spectral region of the three primary colors magenta, cyan and yellow;
It is decomposed into These partial beams are then supplied as electrical color separation signals from the output of the photoelectric conversion device. This color separation signal is also called a primary color signal.

A mask held in accordance with the original image is scanned in synchronization with the original image, and the scanning signal obtained at that time is used to control the sharpening signal, thereby controlling the sharpening signal according to the content of the original image. For this purpose, a mask 4 is fixed on the drum 3. The mask 4 is scanned by a scanning section 10. The dark areas 85 of the mask 4 must be reconstructed using the sharpening signal. track 35
One primary color signal supplied from the photoelectric conversion device 27 via is supplied to two RC elements, differentiated twice by the RC elements, and becomes a sharpening signal. These RC elements are resistors 86, 87 and capacitor 8
It is composed of 8,89. The output signal of the RC element is applied via a polarity inversion stage 90 to a transistor 91 which acts as a signal modulation element or a signal switching element. The output signal of the RC element is further connected to a resistor 92.
The signal is supplied to the input side line 40 of the recording section 11 via. The operating point of transistor 91 is adjusted by resistor 98. The base of the transistor 91 is connected to the diode 93, and the mask 4 generated by the photoelectric conversion device 94 and supplied to the signal amplifier 95
The transmission signal is applied to the diode 93. The scanning beam of the mask 4 is imaged at an image point 96 of the mask 4. The scanning light beam of the mask 4 reaches the photoelectric conversion device 94 via a lens system 97 from a light source (not shown). For this purpose, for example, the light source 12, the lens 1
3, 14 and a mirror 18 can be used, similar to the light beam supply device described above. This light beam supply device is moved in the axial direction along the mask 4 by the feed screw 8 in accordance with the axial movement of the scanning section 10.

The sharpening signal is passed only when the signal generated by the scanning section 10 is weak, that is, when the dark part of the mask 4 is being scanned.

In the embodiment shown, the optical system also has an additional scanning device which scans around the image point 19 of the transparency 2. This scanning device consists of a cathode ray tube 28. A rotating bright spot 30 is generated on the screen 29 of the cathode ray tube 28. The scanning light beam 31 passes from the bright spot 30 via the lens 32, the mirror 17, the lens 14 and the mirror 18 to reach the vicinity of the image point 19 of the transparency 2. The scanning beam 31 is further imaged at an image point 33, which scans the transparency 2. The image point 33 rotates around the image point 19 in synchronization with the bright spot 30 on the screen 29. A light ray 31 modulated by the original image content around the image point 19 reaches the photoelectric conversion device 34 from the image point 33 via the mirror 22 . Photoelectric conversion device 34
An electrical signal, a so-called neighborhood signal, is generated. The scanning drum 1 is rotated so that the entire original surface of the transparency 2 is completely point-scanned and line-scanned;
At the same time, the scanning section 9 is driven by the feed screw 8 and moves along the scanning drum 1 in the axial direction. In that case, a cathode ray tube 28 having a light source 12, a lens 13, a mirror 16, a lens 14, a mirror 18 and a lens 32 is mechanically fixedly connected to the scanning section 9, so that said components move through a predetermined stroke determined by the feed screw. It must be possible to move axially along with the scanning part 9 by the length. As a result, the transparency 2 is dot-scanned and line-scanned in a spiral manner by the relative movement of the scanning drum and the entire scanning section, ie, by the rotation of the scanning drum and the axial movement of the entire scanning section.

The so-called primary color signals generated by the photoelectric conversion devices 25, 26 and 27 correspond to magenta, cyan and yellow, respectively, and reach the switch 38 via lines 35, 36, 37. Only the primary color signals corresponding to the primary colors to be recorded each time are selected by the switch 38. Usually lines 35, 36 and 37
Although a color correction circuit is inserted in , a description of the color correction circuit will be omitted. The signal from the switch 38 is recorded by the recording section 11. The recording unit 11 includes, for example, an amplifier 39. Amplifier 39 is controlled via line 40 and the output signal of amplifier 39 is connected to recording lamp 41.
is applied to A recording lamp 41 generates a light beam 42 . The light beam 42 is imaged by an optical system 43 onto the record carrier located on the drum 3 . The record carrier 5 is made of, for example, a photosensitive material. When the record carrier 5 receives the light beam 42, as a result of the relative movement between the two due to the rotation of the drum 3 and the axial movement of the recording unit 11, a spiral line corresponding exactly to the scanning of the transparency is caused by the light beam 42 on the record carrier 5. recorded in

Simultaneously with the scanning and recording, the photoelectric conversion device 3
4 generates a nearby area signal. This neighborhood signal is supplied via line 44 to an RC element consisting of a resistor 45 and a capacitor 46. The signal supplied via line 35 and decoupling resistor 47 is subtracted from said neighborhood signal in a subtraction circuit 48, and the resulting difference signal is applied to transistor 5.
0 and between the collector and emitter of a transistor 53 via a polarity inversion stage 51. This signal is then superimposed via a variable resistor 54 on the primary color signal of line 40 as a so-called sharpening signal for improving sharpness. If a connection line is used instead of between the collector and emitter of the transistors 50 and 53 and the difference signal is superimposed on the primary color signal via this connection line, known blur masking will be achieved. In contrast to known blur masking, in the embodiment of the invention transistors 50 and 53 are inserted as modulation elements or signal switching elements in the signal path of the near-field signal. When the image point 33 orbits or scans surfaces of various densities while orbiting around the image point 19, the signal from the photoelectric conversion device 34 becomes a high frequency signal with alternating amplitude. This signal is supplied to an amplifier 57 via a resistor 55 and a capacitor 56. A diode 58 is connected downstream of the amplifier 57. Diode 58 is connected to the base of transistor 50 and allows only negative signal amplitudes to pass. A resistor 59 is provided to adjust the operating point of transistor 50, and a resistor 52 is provided to adjust the operating point of transistor 53. Both resistors are connected to the positive terminal of a voltage source (not shown). diode 5
The negative signal supplied from transistor 50
becomes non-conductive, and as a result, from the photoelectric conversion device 34
The sharpening signal being applied to the collector of transistor 50 via RC elements 45 and 46 is blocked between the collector and emitter. Therefore, the sharpening signal is
A high frequency signal having an alternating amplitude is transmitted to the photoelectric conversion device 34.
It is blocked between the collector and emitter of the transistor 50 only if it is supplied by more than 1, ie if the concentration around the image point 19 is not uniform.

On the other hand, if the density around the image point 19 is uniform, the transistor 50 does not block the sharpening signal, and the sharpening signal is fully activated, resulting in improved sharpness. A sharpening signal that improves sharpness is extracted from the neighborhood signal. The nearby area signal is obtained from the rotating bright spot 30 of the cathode ray tube 28, as described above.
FIG. 2 is a block diagram of an electron beam deflection circuit device that causes the electron beam of the cathode ray tube 28 to move in a circular motion. As shown in FIG. 1, this circuit device includes an electron beam deflection circuit 60
and a control circuit 61 that controls the brightness of the electron beam at a constant level. Control circuit 61 that controls the electron beam
will not be explained in detail. This control device supplies a constant voltage to adjust the operating point of the cathode ray tube.

An electron beam deflection circuit for rotating the electron beam is a transformer 6 controlled via a high frequency generator 62.
It is composed of 3. The secondary winding of the transformer 63 is connected to horizontal deflection plates 64, 65 of the cathode ray tube 28. Via a capacitor 66 and a resistor 67, and further through an amplifier 68, the secondary voltage of the transformer 63 is supplied to the vertical deflection plates 69, 70 of the cathode ray tube. As a result, the vertical deflection plates 69,7
The phase of the deflection potential applied to 0 is shifted by 90 degrees from the phase of the deflection voltage of the horizontal deflection plates 64 and 65.
As a result, the electron beam is deflected so that it circulates according to the Lissajieu figure. In this case, it is desirable to make the frequency of the high-frequency generator 62 several times higher than the image point scanning frequency so that the area around the image point to be scanned each time is scanned at the required speed.

The effect of the sharpening signal can be varied by controlling the sharpening signal in relation to only one color selected in the original image. For example, in reproducing skin color, it is desirable to transfer the skin color without sharpening. To this end, a color selection circuit 71 can be provided that supplies a negative signal via the diode 72 only when the selected color is scanned in the original image. A transistor 53 is connected downstream of the diode 72, which becomes non-conducting when the base voltage becomes negative and prevents the sharpening signal from passing between collector and emitter.

Next, the color selection circuit 71 will be explained in detail with reference to FIG. The primary color signals corresponding to magenta, cyan and yellow reach color selection circuit 71 via lines 35, 36 and 37, respectively. First of all, above 3
Differences between the two primary color signals and the corresponding fixed values mgo, cyo, geo are formed. That is, each primary color signal is supplied to one input of operational amplifiers 76, 77 and 78, which are connected as differential amplifiers. On the other input side of the operational amplifiers 76, 77, 78, constant signal values mgo,
cyo and geo are supplied. The outputs of the operational amplifiers are connected to a multiplication stage 82, which multiplies the outputs of the operational amplifiers 76, 77, 78 with each other. The circuit structure of the multiplication stage 82 is well known and, for example, multiplication devices that perform multiplication using the nonlinear characteristic curve of a rectifier or the nonlinear characteristic curve of a vacuum tube are available, so a description thereof will be omitted.

Then the adjusted constant signal values mgo, cyo and
If primary color signals mg, cy, ge approximately equal to geo are supplied via lines 35, 36 and 37, respectively, the signal obtained at the output of multiplier stage 82 is at a minimum. This signal is converted to the maximum signal by amplitude inverter 83 and applied to diode 72. Diode 72 then renders the base of transistor 53 non-conductive so that the sharpening signal is blocked and not supplied to the recording section.

The resulting effects include, for example, the following points:
That is, the skin color scanned in the original image is reproduced without being sharpened by the sharpening signal.

The sharpening signal can also be controlled in other ways depending on the original image content. For example, signals generated in other ways can also be used. For example, it can also be obtained by uniformly and constantly illuminating the image point 33 scanning around the image point 19. The geometric shape of the image point 33 can then be ring-shaped, star-shaped or sector-shaped, for example. When divided into sectors, each sector is separated by a mirror 22 and a corresponding 4
photoelectric conversion devices. By subtracting the minimum signal from the maximum signal among the signals generated by the photoelectric conversion device, a signal that enhances the contrast can be obtained. This signal is transmitted to the signal switching element or signal modulation element 5.
0, 53 or 91 and is further superimposed on the recording signal via line 40.

[Brief explanation of the drawing]

The drawings serve to explain the invention, and FIG. 1 is a schematic diagram of an embodiment of the invention for copying a continuous tone original;
FIG. 2 is a block diagram of a circuit device for rotating an electron beam, and FIG. 3 is an embodiment of a color signal detection circuit used in the copying machine of FIG. 1. 1... Scanning drum, 2... Transparency, 3... Recording drum, 4... Mask, 5... Record carrier, 6...
...Axis, 7...Electric motor, 8...Feed screw, 9...Original image scanning section, 10...Mask scanning section, 11...Recording section, 12...Light source, 13...Lens system, 16,2
1... Hole, 17, 18... Mirror, 19, 33... Image point, 20... Lens system, 22, 23, 24...
Mirror, 28...Cathode ray tube, 29...Screen, 3
0... Light spot, 15, 31... Scanning light beam, 32...
Lens system, 38... Selection switch, 39... Amplifier, 41... Recording lamp, 42... Recording beam, 4
3... Lens system, 47... Decoupling resistance, 48...
Subtraction circuit, 51, 90... Polarity inversion stage, 57...
Amplifier, 60...Electron beam deflection circuit, 61...Control circuit, 62...High frequency generator, 63...Transformer,
64, 65, 69, 70... Deflection plate, 68... Amplifier, 71... Color selection circuit, 76, 77, 78...
... operational amplifier, 82 ... multiplication stage, 83 ... amplitude inverter, 85 ... dark part of mask, 95 ... signal amplifier, 96 ... mask image point, 97 ... lens system.

Claims (1)

[Claims] 1. In an apparatus for controlling the sharpness of a copy of a continuous tone original, which comprises an electro-optical scanning device for the original, a device for deriving a sharpening signal, and a device for superimposing the sharpening signal on the image signal. a mask device having a mask device, and a device for increasing or reducing a sharpening signal superimposed on an image signal using a signal obtained by scanning a partial mask, for the superimposing device. A device that controls the sharpness of a copy of a gradation original.