JPH0470287A - Video printer - Google Patents

Abstract

PURPOSE:To automate the printing of the photograph of prescribed contrast by adjusting the level of a picture signal to be supplied to a printing part based on the result of a weighted average. CONSTITUTION:Digital primary color signals RD, GD, BD stored once in storage circuits 24R, 24G, 24B are judged about the excess and deficiency of the contrast based on the weighted average result of the primary color signal GD of green containing much luminance information. By rewriting them into printing digital primary color signals RDP, GDP, BDP corrected based on the judged result, the picture signal to be supplied to the printing part 4 is automatically adjusted to the proper level.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application in the IM Industry) The present invention relates to a video printer that prints image information input as a video signal or the like, and particularly relates to a video printer that can automatically adjust contrast.

(Prior Art) Japanese Unexamined Patent Publication No. 179677/1983 discloses a video printer equipped with an image quality adjusting means for manually adjusting the image quality of an input video signal.

Furthermore, Japanese Patent Application Laid-Open No. 1-229572 provides means for determining the contrast of an original image, means for storing a plurality of energization data, and means for selecting energization data according to the contrast determination result. A video printer has been disclosed in which a blind image with a predetermined contrast is obtained by controlling the energization time of a heating element in a heating head section according to data.

(Problems to be Solved by the Invention) However, in a video printer equipped with a manual image quality adjustment means, the image quality must be adjusted each time a different image is displayed, which is cumbersome to operate.

On the other hand, a device that selects energization data must have a large number of energization data in order to improve contrast correction accuracy.

This invention was made to solve these problems, and its purpose is to automatically adjust the level of the image signal supplied to the print section to achieve a predetermined contrast and last image regardless of the darkness or lightness of the original image. The object of the present invention is to provide a video printer capable of producing prints of

(Means for Solving the Problems) In order to solve the above problems, the video printer according to the present invention includes weighted averaging means for weighting and averaging at least information related to luminance of the original image signal by weighting a specific range of the original image. The present invention is characterized in that it includes a level adjustment circuit that adjusts the level of the image signal supplied to the print section based on information regarding the luminance obtained by weighted averaging.

(Function) The level of the image signal supplied to the print section is adjusted based on information related to the brightness of the original image signal, so even if the original image lacks contrast or is too bright, it can still be corrected. can be printed automatically.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

Figure 5i%1 is a block diagram of a video printer according to the present invention.

This video printer 1 inputs a composite video signal VC from a television, VTR, etc. and a still image signal VA supplied in an analog RGB format, and prints the original image information in color. It includes a processing section 3 and a printing section 4.

The image memory section 2 includes a Y/C separation circuit 21 that separates a luminance signal Y and a color signal C from a composite video signal VC applied to a composite video signal input terminal 5, and a Y/C separation circuit 21 that demodulates the separated color signal and outputs a 2
A color signal reproducing circuit (decoder) 22 that obtains two color difference signals and reproduces R, G, and B primary color signals by combining them with a luminance signal Y, and samples and samples each of the primary color signals R, G, and B at a predetermined period. Quantized digital primary color signals RD, GD.

A/D converters 23R and 23G convert to BD.

23B, and R temporarily stored in primary color signals RD, GD, and BD.
Memory circuits 24R, 24G, 24B and memory circuits 24R, 24G made up of AM, etc.

0/^ converter 25R, which converts the digital primary color signal read from 24B into analog primary color signals RA, GA, BA;
25G, 25B, a synchronization separation circuit 26 that extracts and outputs various horizontal and vertical synchronization signals Hd and Vd from the luminance signal Y, and writes the storage circuits 24R and 24G and 24B based on the various synchronization signals Hd and Vd. , a control circuit 27 for controlling readout.

In the standby state, the image memory section 2 stores the primary color signals R, G, and B reproduced from the manually inputted composite video signal VC into each A.
/D converters 23R, 23G.

23B at a predetermined period.
Convert to D, BD and each storage circuit 24R324G, 24B
At the same time, the written digital primary color signals RD, GD, and BD are read out in a prescribed order and converted into analog primary color signals RA through the converters 25R, 125G, and 25B.

It is configured to convert into GA and BA and output. Each storage circuit 24R, 24G, 24B stores a digital primary color signal RD for at least one frame.

It has the capacity to store GD and BD.

When a printing command is applied to the printing command input terminal 27a, the control circuit 27 outputs the digital primary color signals RD, GD, and BD for one frame of the video signal to the respective storage circuits 24R, 24G, and 24.
New writing is stopped when writing to B is completed. Then, the control circuit 27 repeatedly reads out the digital primary color signals RD, GD, and BD fixed in the storage circuits 24R, 24G, and 24B at a predetermined frame period, thereby transmitting the original image signal to be printed to the D/A converter 25R. , 25G, and 25B as analog primary color signals RA, GA, and BA.

The control circuit 27 includes a circuit that generates synchronization signals HD and VD corresponding to the synchronization signals Hd and Vd even when the various synchronization signals Hd and Vd from the synchronization separation circuit 26 are not applied. , when the composite video signal VC is applied to the composite video signal input terminal 5, the synchronization signals HD and VD synchronized with the various synchronization signals Hd and Vd output from the synchronization separation circuit 26 are supplied to the signal processing section 3. At the same time, based on these signals HD and VD, the memory circuits 24R,
24G and 24B, and when the composite video signal VC is no longer applied, outputs various synchronization signals HD and VD generated by the timing signal generation circuit to the signal processing section 3, and also outputs various synchronization signals HD and VD generated by the timing signal generation circuit to the signal processing section 3. It is configured to read the stored image information based on the signal.

analog primary color signal RA output from the image memory section 2;
GA, BA and various synchronization signals HD.

The VD is supplied to the signal processing section 3 via the print input selection circuit 6. The print input selection circuit 6 switches the signal input to the signal processing section 3 between the output signal of the image memory section 2 and the still image signal VA supplied from another device (not shown). . In this embodiment, an analog RGB signal is used as the still image signal VA, and the intensity of each color can be specified arbitrarily.The interlocking changeover switch supplies various synchronization signals and signals related to printing commands to the signal processing unit 3. The configuration is such that the original image signal is switched.

The signal processing section 3 inputs the original image signals RI, GI, and BI selected by the printing manual selection circuit 6 and supplies printing primary color signals RP to the printing section 4 .

a level adjustment circuit 31 that adjusts the levels of GP and BP;
Each pressure signal RP, GP, BP of this level adjustment circuit 31
an encoding circuit 32 that manually synthesizes a luminance signal YP and a color signal CP; each output YP of the encoding circuit 32;
Y/C that generates a composite video signal vp based on CP and various synchronization signals HD and VD and outputs it to the monitor terminal 33a.
The mixing circuit 33 and the weighted averaging means 34 for weighting and averaging at least information related to luminance among the original image signals RI, GI, and Bl inputted to the signal processing section 3 by weighting a specific range of the image. , each output signal RP, GP of the level adjustment circuit 31 based on the output of the weighted average means 34.
, BP.

The level adjustment circuit 31 controls each original image signal R1°G1. B.I.
Voltage-controlled variable gain wideband amplifiers (hereinafter referred to as video amplifiers) 31R, 31G, and 31 provided correspondingly to each
These video amplifiers 31R, 31G, 3
1B is a DC voltage VDC applied to the gain control terminal 31a.
The structure is such that the gain can be increased or decreased within a predetermined range based on. In addition, these video amplifiers 31R931G
, 31B are configured such that their gains decrease as the DC voltage VDC increases.

The weighted average means 34 includes an area generator 40 that generates a signal related to a weighted range and a weighted coefficient.
, a clamp pulse generation circuit 41 which inputs the horizontal synchronizing signal HD and generates a clamp pulse CLIP in synchronization with the horizontal synchronizing signal HD, and which inputs a large luminance signal YP and outputs a luminance signal YA which has undergone DC component correction to align the pedestal levels. Clamp circuit 42, gate circuit 43, and integration circuit 44
, a voltage holding circuit 45.

The area generator 40 generates a voltage signal HW for horizontal weighting based on the horizontal synchronization signal (D), a voltage signal HW for the horizontal weighting and a voltage signal for vertical weighting based on the vertical synchronization signal VD. The vertical weighting that generates VW is the output voltage HW of the circuit 40b, and each weighting is the output voltage HW of the circuits 40a and 40b.

Using VW as input, weighting corresponding to the product is the voltage signal W
and an arithmetic circuit 40C that outputs.

FIG. 2 is an explanatory diagram showing an example of weighting.

In this embodiment, even when the upper part of the screen is bright (for example, when the sky is bright above in a landscape painting), the voltage signal HW is weighted in a chevron shape in the horizontal direction so that the contrast in the center of the screen is appropriate. In the vertical direction, the trapezoidal weighting is the voltage VW.
Each weighting is generated by circuits 40a and 40b, and the weighting of the luminance signal in the hatched area on the screen is made more intense.

Note that the vertical weighting shown in FIG. 2 is based on the voltage waveform VW.
shows the case of non-interlaced scanning, and in the case of interlaced scanning, the voltage waveform will be different from that shown.

The voltage signal W generated by the area generator 40 and weighted is
is applied to the control input terminal 43a of the gate circuit 43. This gate circuit 43 varies the transfer coefficient between the signal input terminal 43b and the signal output terminal 43C based on the voltage applied to the control input terminal 43a, and is, for example, a voltage-controlled amplifier or attenuator, or Weighting is applied to the gate of an FET (field effect transistor) by a circuit or the like that applies a voltage signal W and uses the drain and source as input/output terminals.

The luminance signal YA output from the clamp circuit 42 is applied to the input terminal 43b of the gate circuit 43, and the output terminal 4
The weighted luminance signal YB applied from 3C is inputted to an integrating circuit 44 having a predetermined integration time constant, and the integrated output YC is held in a voltage holding circuit 45.
The held voltage is applied to each video amplifier 31R, 31G, 3
The configuration is such that it is output as a direct current voltage VDC for 1B gain control. Note that the voltage holding circuit 45 is configured to sample the integrated output voltage YC for one frame based on the vertical synchronizing signal VD and hold that voltage. When the voltage is outside the set voltage range (such as when no video signal is input), a specific preset DC voltage VDC is output to maintain the gain of each video amplifier 31R, 31G, and 31B at the initial state. It is composed of

With the above configuration, the weighted average means 34 applies the area generator 4 to the signal YA, which has the same pedestal level of the luminance signal YP output from the encoder circuit 32.
An operation is performed for each frame to obtain a voltage signal YC, which is a weighted average of luminance information, by integrating the signal YB in an integrating circuit 44 with a weight given to the range specified by 0, and then obtaining a voltage signal yc, which is a weighted average of luminance information. is held in a voltage holding circuit 45 and output as a DC voltage VDC that controls the gain of each video amplifier 31R, 31G, and 31B.

Therefore, the printing primary color signal RI input to the signal processing section 3,
If the contrast between GI and Bl is insufficient, the weighted average specific force YC is low, and the gain control DC voltage V
DC becomes a low voltage, and each video amplifier 31R, 31G
, 31B. Conversely, if the contrast of the printing primary color signals R, I, Gl, BI is excessive, the gain of each video amplifier 31R, 31G, 31B is reduced.

Therefore, the print source and color signals RP and GP are the outputs of the respective video amplifiers 31R and 31G31B.

BP is automatically adjusted to the appropriate contrast condition.

The monitor terminal 33a receives print primary color signals RP and GP whose levels are adjusted by the level adjustment circuit 31.

This is an output terminal for monitoring images related to BP on a monitor television or the like (not shown). In this embodiment, assuming a composite video signal input type monitor television, the Y/C mixing circuit 33
The configuration is such that the composite video signal is output via the Y
When using a monitor equipped with a /C separation input, a configuration in which each output signal YP, CP of the encoder circuit 32 is directly supplied may be used. In addition, when using a monitor equipped with analog RGB input, etc., each output signal RP of the level adjustment circuit 31.

A configuration in which GP and BP are directly supplied may be used.

Furthermore, although the area generator 40 is configured to generate a signal that weights a specific range set in advance, the monitor TV is provided with means for specifying the area to be weighted by operating a cursor, pointing device, etc. , this designated area information is supplied to the area generator 40 in the signal processing section 3, and weighting is performed based on the luminance information of the designated area on the screen of the monitor television, and each video amplifier 31R, 31G.

It is also possible to adopt a configuration in which the gain of 31B is controlled.

The print unit 4 receives printing primary color signals RP and GP.

It includes a selector circuit 4a for selecting BP, a ^/D converter 4b, a print signal processing circuit 4c, a thermal head 4d, etc., and outputs each printing primary color signal RP.

The thermal head 4d is driven for each GP and BP to perform multi-gradation color printing.

Note that when the printing operation control signal ps outputted from the control circuit 27 in the image memory section 2 is inputted to the printing section 4, the level adjustment operation based on the brightness information in the signal processing section 3 is completed. The printing operation is configured to be performed after a certain amount of time has elapsed. In addition, a level adjustment completion voltage detection circuit is installed in the weighting element of the signal processing unit 3 and the leveling stage 34 to detect whether the voltage held last time and the voltage held this time are the same or within a predetermined voltage difference. and is configured to be able to start a printing operation based on the detection output,
The time required to start printing may be shortened.

With the above configuration, the original image signals R1, Gl, BI manually input to the signal processing section 3 are the original image signals RI, GI, B
Since the level supplied to the print section 3 and the monitor terminal 33a is adjusted based on the information regarding the brightness of the original image signal RI.

G1. Even if the BI contrast is insufficient or too bright, printing can be automatically performed with the correction corrected, and the contrast can be automatically corrected by connecting a monitor TV etc. to the monitor terminal 33a. You can check the image of the condition.

Although this embodiment has described a configuration in which the contrast is corrected based on the luminance signal YP that is the output of the encoding circuit 32, a configuration in which the contrast is corrected based on the green primary color signal GP containing a large amount of luminance information has been described. You may.

Further, the signal processing section 3 shown in FIG.
Since the gain of 1 is controlled by a feedback loop using analog signal processing, high-speed contrast correction processing can be performed with a relatively small circuit scale.

Next, a third embodiment of the video printer according to the present invention will be described.
The explanation will be made with reference to the block diagram shown in the figure.

This video printer 51 includes an image memory section 52, a monitor interface section 53, and a print section 54.

The image memory unit 52 includes a Y/C separation circuit 21 that separates a luminance signal Y and a color signal C from a composite video signal VC applied to a composite video signal input terminal 55, and reproduces primary color signals of R, G, and B. A color signal reproducing circuit (decoder) 22, A/D converters 23R, 123G, 23B that convert each primary color signal R, G, B into a digital primary color signal, and storage circuits 24R, 24G, 24B configured with RAM etc. Memory circuit 24R92
D/A converters 25R and 25G that reconvert the digital primary color signals read from 4G and 24B into analog primary color signals;
25B, a synchronization separation circuit 26, a control circuit 56, an area specifying means 57 for specifying an area for weighted averaging, a weighted averaging means 58, and each storage circuit 24R, 24G, 24B based on the output of the weighted averaging means 58. and calculation means 59 for performing a predetermined calculation on the digital primary color signal stored in the digital primary color signal to obtain a contrast-corrected digital primary color signal.

In the standby state, the image memory unit 52 stores primary color signals R, G, B reproduced from the input composite video signal VC.
to each A/D converter 23R, 23G.

Digital primary color signals arrive at a predetermined synchronization via 23B, G
Convert to D, BD and each memory circuit 24R124G, 24B
0/^ converters 25R, 25G, 25 by reading out the written signals in a predetermined order.
It is configured to convert the signals to analog primary color signals RA, GA, and BA via the signals B and output them. Thereby, the composite video signal YC can be monitored via the monitor interface section 53 on a monitor television or the like (not shown). Each of the storage circuits 24R, 24G, and 24B has a capacity capable of storing at least one frame's worth of digital primary color signals RD, GD, and BD.

When a printing command is applied to the printing command input terminal 56a, the control circuit 56 outputs the digital primary color signals RD, GD, and BD for one frame of the video signal to the respective storage circuits 24R, 24G, and 24.
At the time of writing to B, a ^/D output control signal ADCE is generated to control the output of each A/D converter 23R, 23G, and 23B to a high impedance state. Then, the control circuit 56 outputs a weighted average processing start signal AVES to start the weighted average means 58.

The weighted averaging means 58 weights and averages the green digital primary color signal GD read out from the storage circuit 24G for all pixels, and the weighting for each pixel given from the area specifying means 57 is applied to the input terminal based on the constant WD. A multiplication circuit that multiplies (or divides) the green digital primary color signal GD applied to 58a, an integration circuit that integrates the multiplication output for each pixel, and a weighted average that divides the integration results of all pixels by a predetermined number. The output AVEW is composed of a division circuit that outputs an output terminal 58b.

The area specifying means 57 stores preset weighting constants for each pixel or preset pixel group area.
OM, etc., and weighting of the pixel primary color signal GD currently given to the weighted averaging means 58 based on the address signal ADDR given from the control circuit 56 is performed by a coefficient WD.
It is configured to output .

Note that the area specifying means 57 may be configured to generate a predetermined weighting coefficient for a specified area on the screen of the monitor television.

The calculation means 59 performs a corresponding multiplication or division operation based on the weighted average output AVEW, and when the control input terminal 59a is at H level, a predetermined value is applied to the red digital primary color signal RD applied to the input terminal 59b. Similarly, predetermined calculations are performed on the digital primary color signals GD and BD given to the input terminals 59e and 59h specified by the control input terminal 59d or 59g, and the result is sent to the output terminal 59c. 59f and 59i.

, the control circuit 56 activates the weighted average means 58 to obtain a weighted average output AVEW for all pixels, and then outputs contrast correction signals RC and GC for each color.

BC is set to H level in sequence, and each memory circuit 24R124G
, 24B, the digital primary color signals RD, GD,
When reading out each pixel from the BD, the weighted average output is AVE.
The printing primary color signals RDP, GDP, and BDP subjected to contrast correction corresponding to W are obtained by the calculation means 59, and are written to the address of the read pixel.

Note that the control circuit 56 outputs the D/^ conversion control signal DAC while performing the weighted average calculation and the contrast correction calculation.
E stops the operation of each D/^ converter 25R, 125G, 25B, and also stops the operation of the memory circuits 24R, 24G, 2.
The read period of 4B is controlled to match the calculation processing speed of the weighted average means 58 and the calculation means 59.

The control circuit 56 is connected to the memory circuits 24R124G, 24
When contrast correction is completed for all B pixel information, the operation of the D/C converters 25R125G and 25B is restarted, and a print start command is output to the print section 4 to start the print operation.

With the above configuration, the memory circuits 24R124G, 24B
The digital primary color signals RD, GD, and BD that have been stored once are judged whether the contrast is excessive or insufficient based on the weighted average result of the green primary color signal GD, which contains a lot of luminance information, and the print is corrected based on the judgment result. Digital primary color signal RDP
, GDP, and BDP, so print section 4
The image signal supplied to the image signal is automatically adjusted to the appropriate level.

Note that the weighted average means 58 includes each memory circuit 24R, 24G.
, 24B may be used to determine the luminance-related signals from the three primary color signals read from the three-color primary color signals, and weighted average of the luminance-related signals may be performed.

In addition, the printing digital primary color signal RD after contrast correction
A storage circuit for temporarily storing P, GDP, and BDP is provided independently, and D-converters 25R and 25G are provided.

25B may be switched so that the signal supplied to the monitor television or the like via the monitor interface section 53 is not interrupted.

The monitor interface section 53 includes an encoder circuit 32 and a Y/C mixing circuit 33. The printing section 54 is the same as that shown in FIG. 1, except that the printing start ffIJ control conditions of the print signal processing circuit 4c are different.

(Effects of the Invention) As explained above, the video printer according to the present invention has
The structure is such that at least information related to brightness of the original image signal is weighted and averaged by weighting a specific range of the original image, and the level of the image signal supplied to the print section is adjusted based on the weighted average result. Prints with a predetermined contrast can be automatically obtained regardless of the darkness or lightness of the original image signal without changing the print section of the printer.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a video printer according to the present invention, FIG. 2 is an explanatory diagram showing an example of weighting a specific area of an image, and FIG. 3 is a block configuration diagram of a video printer according to another embodiment. It is. 1.51... Video printer, 2.52... Image memory section, 3... Signal processing section, 4, 54... Print section, 5, 55... Composite video signal input terminal, 23R12
3G, 23B...A/D converter, 24R, 24G. 24B...Memory circuit, 25R, 25G, 25B...
D/^ converter, 27.56--control circuit, 27a. 56a... Print command input terminal, 31... Level adjustment circuit, 34... Weighted average means, 40... Area generator, 43... Gate circuit, 44... Integrating circuit, 45... Voltage holding circuit, 57...Area specifying means, 58...Averaging means, 59...Arithmetic means constituting the level adjusting means, AVEW...Weighted average output, C
1c p...color signal, Hd, Vd, HD, VD-...
・Various synchronization signals, HW...vertical weighting is a voltage signal, R, G, B...primary color signals, RA, GA, BA...
・Analog primary color signal, RD, GD, BD...Digital primary color signal, RDP, GDP, BDP, RP, GP
, BP...printing primary color signal, VC...composite video signal, VDC...DC voltage for gain control, VW...vertical weighting is a voltage signal, Wl)...weighting is a coefficient, Y
, YP...luminance signal, YC...integral output. Patent applicant: Japan Victor Co., Ltd. Agent
Person Patent Attorney 2 1) Yong-Immediate Question

Claims (1)

[Claims] Weighted averaging means that weights and averages at least information related to brightness of the original image signal by weighting a specific range of the original image, and an image signal supplied to the printing unit based on the information related to brightness obtained by weighted averaging. A video printer characterized in that it is equipped with a level adjustment circuit that adjusts the level of the video printer.