JP2806521B2 - Video printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video printer that creates a hard copy from an input video signal, and more particularly, to a multi-freeze in which a plurality of frames are embedded and synthesized on one screen. It relates to a video printer that also creates images. [Prior Art] Video printers that hard copy video images include:
CRT video printers, laser printers and the like are known. The video printer receives a video signal reproduced by a video tape recorder, a real-time video signal photographed by a television camera, or a video signal obtained by reproducing a video floppy recording an image photographed by an electronic still camera. . This input video signal is
The band-limited video signal is sampled and quantized by an A / D converter. In this A / D converter, the video signal band-limited by the filter is divided into two based on the sampling theorem.
Sampling is performed at more than twice the frequency. The video signal sampled in this manner is subjected to color correction, gradation correction, image synthesis, and the like in the image processing unit, and then subjected to positive / negative conversion, and then sent to the CRT in a CRT video printer. The photosensitive material is printed with the negative image displayed on the CRT. [Problems to be Solved by the Invention] By the way, in such a video printer, a plurality of photographed frames are inserted into one screen and synthesized to create a multi-freeze image, which is hard-copied as an index photograph or the like. Attempts have been made to use it. In this case, after sampling one frame of the video image as it is in the case of hard copying, the video signal is thinned to reduce the size, and a multi-freeze image is formed from the plurality of frames of the video signal. I try to print. However, when a video signal is thinned out to create a multi-freeze image of, for example, 4 × 4 frames, the actual sampling frequency becomes a quarter of the sampling frequency performed by the A / D converter. Therefore, for example, even if the A / D converter samples a 4.5 MHz video signal at 12 MHz which is twice or more the frequency, the actual sampling frequency becomes 3 MHz after thinning,
The sampling theorem will break. FIG. 4 shows such a state, in which the reproduced video signal represented by the dotted line cannot faithfully restore the original video signal represented by the solid line. Therefore, on the printed multi-freeze screen, moire appears in a striped pattern,
Image quality deterioration such as oblique jaggy is conspicuous. This deterioration in image quality is caused by so-called aliasing noise, in which the Nyquist condition is disturbed and the lower sideband component of the sampling frequency overlaps with the original signal. The present invention has been made to solve such a problem, and provides a video printer capable of making a hard copy of a multi-freeze image having high reproducibility and resolution in the same manner as a normal single-frame print. The purpose is to do so. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a first low-pass filter having substantially the same band as a video signal and extracting a low-frequency component of an input video signal; A second low-pass filter having a narrower bandwidth than the low-pass filter for extracting the low-frequency component of the input video signal;
When the video image of the frame is hard copied as it is, the output of the first low-pass filter is taken out, and when the multi-freeze image obtained by embedding a plurality of frames into one screen and making a hard copy is taken, the output of the second low-pass filter is taken out Means, an A / D converter for performing sampling and quantization on the video signal extracted from the selecting means, and
An image processing unit that performs color correction and gradation correction on the video signal from the / D converter, and when a single frame of video image is hard copied as it is, the corrected one-frame video signal from the image processing unit Is stored in the memory, and when a multi-image obtained by inserting a plurality of frames into one screen and making a hard copy is copied, a multi-image obtained by thinning out the corrected video signal of each frame from the image processing unit and inserting and combining the frames Means for storing the video signal of the multi-freeze screen in the memory.
× N (M and N are integers of 2 or more, M represents the number of frames in the scanning line direction, and N represents the number of frames in the direction perpendicular to the scanning line). sometimes,
The sampling frequency in the sampling in the case of the f _S, f _S
/ (2M) or less. [Operation] The input video signal is input to the first low-pass filter and the second low-pass filter. The selection means is
At the time of hard copy of one frame of video image, a video signal passed through the first low-pass filter is extracted, and at the time of hard copy of a multi-freeze image, a low-frequency video signal passed through the second low-pass filter is extracted. Hereinafter, an example in which the present invention is applied to a CRT video printer will be described with reference to the drawings. [Embodiment] In FIG. 1 schematically showing a CRT video printer according to the present invention, a video floppy player (hereinafter referred to as a VF player) 1 is provided as an image input unit. VF player 1
Is loaded with a recorded video floppy, and reproduces, for example, a color image recorded on the video floppy. Since the reproduced color image is an NTSC signal, it is separated by the decoder 2 into a red video signal R, a green video signal G, and a blue video signal B. These three color video signals
It has a bandwidth of about 4.5 MHz and is sent to a low-pass filter 3 and a low-pass filter 4 connected in parallel. This low-pass filter 3 and low-pass filter 4
It is provided to limit the bandwidth to less than half the sampling frequency. The low-pass filter 3 has almost the same bandwidth as the video signal having a bandwidth of 4.5 MHz, and passes the input video signal as it is. The lowpass filter 4
It is provided for creating a multi-freeze image. As shown in FIG. 3, the number of frames in the scanning line direction is M, and the number of frames in the direction orthogonal thereto is N (M and N are 2 or more). integer), when the sampling frequency is f _S, it serves the input video signal so as to limit the f _S / (2M) less bandwidth. In this embodiment, a 4 × 4 multi-freeze image,
Since a sampling frequency of 12 MHz is set, the cutoff frequency of the low-pass filter 4 is set to about 1.5 MHz. The three-color video signals output from the low-pass filter 3 or the low-pass filter 4 are selectively extracted by a first selector 6 controlled by a CPU 5 and sent to an A / D converter 7. In the A / D converter 7, the analog video signal inputted is sampled at a set sampling frequency f _S to 12 MHz, and outputs a digital signal with quantization. The video signal digitized by the A / D converter 7 is
It is sent to the second selector 10. This second selector 10 has
The video signal input from the D converter 7 or the bus line 9 is selectively input to the frame memory 8. The frame memory 8 is composed of three memory sections each of which independently stores R, G, B one frame at a time, and each has an information storage capacity of, for example, 640 × 480 pixels.
Write and read operations are performed in accordance with the command signal. The three color video signals read from the frame memory 8 are sent to the image processing unit 11 via the bus line 9. The image processing unit 11 performs a color correction process and a gradation correction process on the video signal sent from the frame memory 8. The image-processed video signal is sent to the second selector 10 or the frame memory 13 via the bus line 9. In order to create a multi-freeze image in which a plurality of frames are inserted and synthesized, video signals from the frame memory 8 are converted into X and Y
The data is read out while being thinned out by 1/4 in the direction and subjected to size reduction processing, and sent to the image processing unit 11 via the bus line 9 to perform image processing. After this image processing, the frame memory 13
Is written in a predetermined area and is fitted and synthesized. The frame memory 13 is composed of three memory sections for independently storing R, G, and B. If the number of pixels of the frame memory 13 is 1280 × 960, for example, one
The resolution becomes good because it is sufficient to thin out the data by / 2. The monitor system includes a D / A converter 16, a driver 17, for example, a color C
The monitor 18 is composed of an RT, and the monitor 18 displays one frame of a color positive image and a multi-freeze image.
The printing system includes a negative / positive inversion circuit 21, a D / A converter 22, a selector 23, a driver 24, and a monochrome CRT 25. The CRT 25 responds to the video signals of each color selectively extracted by the selector 23, and outputs a red, green, and blue image (exactly, red, green,
The negative image of the blue image) is sequentially displayed in black and white. A photosensitive material, for example, a color paper 26 is disposed facing the CRT 25, and an image displayed on the CRT 25 is formed on the color paper 26 by the printing lens 27. Red (R), green (G), and blue (B) color separation filters 29, 30, and 31 are arranged in the optical path 28 of the printing lens 27. When printing a video image, the filter driving unit 32 sequentially inserts the color filters 29 to 31 into the optical path 28 to perform sequential exposure on the additive color surface. The shutter 33 includes a shutter control unit 34
The opening and closing are controlled once, and when the video image is printed, the opening and closing are performed once for each color, that is, three times in total. The color paper 26 wound in a roll shape is intermittently pulled out by a pair of pull-out rollers 36 and set at an exposure position formed behind a mask 37. At this exposure position, when a predetermined number of frames are exposed, the color paper 26 is cut into a short shape by a cutter 38 and sent to a development processing unit 41 by a feed roller 39. In the development processing section 41, color paper
26 is passed through each processing tank for photographic processing, and finally cut into individual frames by a cutter 42 before being discharged to a tray 43. Next, the operation of the video printer having the above configuration will be described with reference to FIG. When the keyboard 12 is operated to instruct the hard copy of one frame of video image as it is, the VF reproducer 1 starts reproducing the video image, and the NTSC signal for one frame output from the VF reproducer 1 is decoded. 2
Is separated into three color video signals. These three-color video signals are input to the low-pass filters 3 and 4 and band-limited. The selector 6 selectively extracts only the frequency of 4.5 MHz or less that has passed through the low-pass filter 3 and sends it to the A / D converter 7. The A / D converter 7 performs sampling and digital conversion on the video signal, and sends it to the frame memory 8. The three-color video signals once stored in the frame memory 8 are repeatedly read out at a constant cycle, sent to the image processing unit 11 via the bus line 9, and subjected to color correction and gradation correction. You. The image-processed video signal is returned to the frame memory 8 via the bus line 9 and the second selector 10. The video image is sent to the monitor system via the third selector 14 and displayed on the monitor 18. By observing the monitor 18, if the image processing is found to be good, the keyboard 12 is operated to input a print command to the CPU 5. The CPU 5 operates a printing system to convert one frame of a video image into a hard copy. That is, at the time of this printing, the video signal that has been subjected to image processing and read from the frame memory 8 is:
The signal is input to a selector 23 via a negative / positive inverting circuit 21 and a D / A converter 22 via a third selector 14. The selector 23 is
First, for example, take out the red video signal, and
To a black and white CRT 25 through which the red image signal is converted to luminance and displayed on the CRT 25. While the CRT 25 is emitting light, the red filter 29 is inserted into the optical path 28, so that the image on the CRT 25 is converted to a red image. In this state, the shutter 33 is opened for an exposure time determined according to the red sensitivity of the color paper 26, and a red image is printed on the color paper 26 during this time. After the exposure of the red image, the shutter 33 is closed, during which the red filter 29 is retracted, and the green filter 30 is inserted instead. At the same time, the CRT 25 displays a green image in black and white. Immediately after this, the shutter 33 opens,
The black and white image displayed on the CTR 25 is converted into a green image by the green filter 30 and is exposed on the color paper 26. Similarly, the blue image displayed on the CRT 25 is exposed on the color paper 26, and the three color plane sequential exposure is completed. In this way, video images are read out one frame at a time from the VF player 1 and printed on the color paper 26. And
When a certain number of frames are printed, the cutter 38 operates to selectively cut off the exposed portion. The cut short color paper 26 is subjected to photographic processing in the development processing section 41, and then separated into individual frames by the cutter 42, and
It is discharged to 43. Next, when the hard copy of the multi-freeze image is instructed by operating the keyboard 12, the VF reproducer 1 starts to operate, and sequentially reproduces the video image of 16 continuous frames. The video signal of each frame is separated into three-color video signals by the decoder 2 and input to the low-pass filter 3 and the low-pass filter 4 in parallel. In the creation of the multi-freeze image, since the first selector 6 has selected the low-pass filter 4, a three-color video signal whose band is limited to 1.5 MHz or less through the low-pass filter 4 is extracted and A / D-converted. It is sent to the converter 7. The A / D converter 7 performs sampling at a sampling frequency of 12 MHz, converts the digital data to digital data, and sends the digital data to the frame memory 8. When reading the video signal from the frame memory 8, the CPU 5 thins out the video signal by 1/4 in the X and Y directions to reduce the size. FIG. 2 shows this sampling state. In other words, it is shown that by cutting the high frequency portion of the video signal according to the sampling theorem with respect to the substantial sampling frequency after thinning out to a 4 × 4 screen, the signal can be almost faithfully restored as shown by the broken line. .
If the low-pass filter 4 has a high cutoff frequency,
When a signal of a higher frequency comes, faithful reproduction cannot be performed as shown in FIG. The video signal read out by thinning is sent to the image processing unit 11, where the video signal is corrected in color and gradation, and then written in a predetermined area of the frame memory 13. The video signal of each frame reduced in size is written in the frame memory 13 in this way, and the image synthesized by this writing is displayed on the monitor 18. After confirming on the monitor 18 that the video signal of 16 reduced frames has been written,
A print command is issued by the keyboard 12, the video signal embedded and synthesized by the frame memory 13 is read, and transmitted to the print system. Then, similarly to the above-described printing of one frame of a video image, the three-color images are sequentially displayed on the CRT 25 and printed on the color paper 26 by the three-color surface sequential exposure. When developed after printing, a multi-freeze photograph 44 is created as shown in FIG. In the above embodiment, the reproduction of a video floppy that has been field-recorded by an electronic still camera has been described. However, image recording by an electronic still camera includes frame recording. In that case, a video signal recorded on any one of the two tracks used for field recording may be extracted and stored in the frame memory 8 as one frame. [Effects of the Invention] As described in detail above, according to the present invention, when a single video image is hard copied as it is, the first video image is used.
Extract the output of the low-pass filter of
When a multi-freeze image of M × N (M is the number of frames in the scanning line direction, N is the number of frames in the direction perpendicular to the scanning line) synthesized and fitted to the screen is hard copied, the output of the second low-pass filter is selected. Means, wherein the first low-pass filter has substantially the same band as the video signal, and extracts the low frequency component of the input video signal;
Low-pass filter for multi-freeze screen,
The sampling frequency in the sampling in the case of the f _S, f _S
/ (2M) bandwidth or less, so it is possible to obtain high quality prints with sufficient sharpness and no aliasing noise for both video print for each frame and multi-screen print for multiple frames. become able to. As described above, in addition to hard-copying one frame of video image, when creating a multi-freeze image, it is also possible to limit the band with the second low-pass filter and hard copy the multi-freeze image without breaking the sampling theorem. it can. Therefore, a moire image or the like does not occur unlike the related art, and a multi-freeze image with little image quality deterioration can be obtained. When a video image of one frame is hard copied as it is, a corrected video signal of one frame from the image processing unit is stored in the memory, and a multi-image obtained by fitting a plurality of frames into one screen and combining them is hard. At the time of copying, the video signal of the multi-image obtained by thinning out the corrected video signal from each frame from the image processing unit and inserting and synthesizing is stored in the memory, so that the image processing unit performs color correction and gradation for each frame. Since the correction is performed, in addition to the frames being almost in the same finished state, the frames of each sub-screen in the multi-image are also almost in the same finished state, and a high-quality multi-image is obtained.
In addition, since the same printing system is used for single frame printing and multi-screen printing, it is possible to switch between video printing for each frame and multi-screen printing for multiple frames on the same recording material as needed. Can be performed, and the configuration and operation are simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of a video printer according to the present invention. FIG. 2 is a waveform diagram showing a sampling state when a multi-freeze image is created. FIG. 3 is an example of a multi-freeze photograph in which a synthesized video image is printed. FIG. 4 is a waveform diagram showing a conventional sampling state when a multi-freeze image is created. 3,4 Low pass filter 6 Selector 7 A / D converter 8,13 Frame memory 11 Image processing unit 44 Multi-freeze photo.

   ────────────────────────────────────────────────── ─── Continuation of front page       (56) References JP-A-62-152284 (JP, A)                 JP-A-59-158685 (JP, A)                 JP-A-61-238184 (JP, A)                 JP-A-60-214000 (JP, A)                 JP-A-60-70551 (JP, A)                 JP-A-61-285880 (JP, A)

Claims (1)

(57) [Claims] A video printer that performs sampling and quantization on an input video signal and then stores it in a memory, reads out the video signal from this memory and creates a hard copy, and has a bandwidth substantially the same as that of the video signal. A first low-pass filter for extracting a low-frequency component of the input video signal; a second low-pass filter having a narrower bandwidth than the first low-pass filter and extracting a low-frequency component of the input video signal; Selecting means for extracting the output of the first low-pass filter when hard-copying the video image as it is, and extracting the output of the second low-pass filter when hard-copying a multi-freeze image obtained by inserting a plurality of frames into one screen and combining An A / D converter that performs sampling and quantization on the video signal extracted from the selection means; An image processing unit that performs color correction and gradation correction on the video signal from the A / D converter; and when a one-frame video image is hard-copyed as it is, the corrected one-frame image from the image processing unit is used. Is stored in the memory, and a plurality of frames are inserted into one screen, and when a multi-image is synthesized by hard copy, the video signal of each corrected frame from the image processing unit is thinned out and inserted. Means for storing a video signal of a multi-image in the memory, wherein the second low-pass filter has a multi-freeze screen of M × N (M and N are integers of 2 or more, and M is the scanning line direction). represents the number of frames, when N is a layout image on a matrix of representing the number of frames direction orthogonal to the scanning line), the sampling frequency of the sampling in the case of the f _S, f _S / (2M) or less Video printer being characterized in that so as to have a bandwidth.