JPH0195677A - Method and apparatus for multiscreen digital display - Google Patents

Abstract

PURPOSE: To form a picture without any visible distortion by selectively blanking the multiple copied lines in an odd field and an even field. CONSTITUTION: The blanking of every four lines is operated in the odd field of an extended image, and the blanking of the first two lines of the four lines in an even field is operated. For example, when lines in the displayed odd and even fields are expressed with dots, and the blanking-processed lines are expressed with a character B, the continuous three lines in the odd field copy the same video lines, and the continuous two odd video lines copy the same lines from the odd video field. As a result, only three lines are omitted in continuous 8 lines in each group expressing video lines in the odd field of an original image and video lines in the following even field in an extended image. Thus, distortion in a composite image on a screen can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for displaying an image on multiple video screens, such as a television network, and more particularly to A method and apparatus for preventing disturbing visual artifacts and distortions in images.

When a video signal is input to a normal television φ set, ie, a monitor, the size of the image is of course
Limited by the size of the display screen of the set or monitor, the ability to create special effects is limited. Accordingly, FIG. 1(2) shows an image in the form of the letter A displayed on the screen 10 of a television receiver or monitor in response to the receipt of a video signal corresponding to this image. Furthermore, it is possible to combine multiple television receivers or monitors to form one large image. Thus, four rows by four television receivers or monitors are each stacked on top of each other and respond to the same signal to obtain an independent image of the letter A on their respective display screens 11-26. Furthermore, by modifying the video signal corresponding to the characters and applying it to the television receiver or monitor of FIG. It is also possible for the image to form an enlarged image. This effect can be created by modifying the signal and applying the signal to different television sets or monitors corresponding to different image parts.

Images of the format shown in FIGS. 1υ and 1(f) are useful, for example, for visible transactions, advertisements, trade exhibitions, etc.

Enlarging the image to be displayed by a factor N requires dividing by the factor N the number of lines from the video input signal applied to each television receiver or monitor. For example, if the count N = 4 and the original video signal corresponds to 525 lines, of which about 480 lines are normally displayed, the original video signal is divided by a factor of 4, so the original 125 lines only will be displayed on the enlarged television receiver. Furthermore, only 1/N of each line will be displayed on each television receiver. The division of such a signal, and the portion displayed on each display screen, is shown in FIG. Segmentation is accomplished, for example, by inputting the composite video signal into memory and addressing each television receiver to play only a determined portion of the stored data. Of course, in such an arrangement it is preferred that each line or portion of a line be repeated N times in succession to avoid excessive blank lines on each display screen. where N is the number of vertically stacked display screens.

In the illustrated example, each display screen displays only one-fourth of the video signal line forming the original image, so the modification of the signal involves selecting the desired portion of the video line and adjusting it in the temporal direction. It must be stretched to cover the entire width of the display screen.

If special care is not taken to filter the signal when applied to each television set or monitor, the image will be subject to visual artifacts that will be obtrusive and loud. These artifacts arise because the transmitted image or frame is in the form of two interlaced fields, i.e. all of the odd lines corresponding to the first field are applied in the first period of e.g. This is due to the fact that all even lines of the image corresponding to are transmitted in successive subsequent periods, for example 1/16 seconds. The results are shown in FIG. 3 for the case representing lines 100-108 of an image corresponding to a video signal. Such a signal is said to be "interlaced" because the two fields are displayed spatially alternating; two 1/16 second fields are used to create a complete 1/30 second image or frame. Build.

When a video signal is "scaled" to display an image on multiple display screens, the line numbers (i.e. numbering from the top line of the frame down) are used to define the overall image displayed by the multiple display screens. It is clear that this does not directly correspond to the display number. It is therefore clear that the total number of lines of the plurality of display screens is N times the number of lines of the original video signal, since each display screen has the same line number as that displayed in the original video signal. where N is the number of vertically stacked display screens. For example, if four display screens are stacked vertically, each line of the original video signal can be stacked vertically on the composite display screen without requiring any further steps to ensure proper alignment.
It is clear that the lines are displayed separated from each other (description of the contents of the remaining lines will be omitted here). Therefore, considering the interlace effect in the enlarged image,
Again, 4 stacked vertically in the composite image.
It is clear that for one display screen, line r in the original image corresponds to line R in the enlarged image according to the following relationship:

R-4Reven ven Thus, in this example, lines 100-108 in the image of the original video signal correspond to lines in the range 396-426 of the enlarged image according to the method shown in FIG.

The video signal is present on only part of the line, i.e. 1 in the example shown.
The enlarged image produced by the technique of FIG. 4 is unsatisfactory because it is displayed only at 1/4. To solve this problem, it is of course possible to repeat each video signal line four times in succession in its field, for example in the manner shown in FIG. In this example, the original line 100 of one field is reproduced with lines 394°396.398 and 400 of the expanded field, and line 101 of the other field is reproduced with lines 395.397.
It was displayed on a96 and 401.

However, it is clear that the enlarged image shown in FIG. 5 is visually severely degraded because the spatial relationships in the original image are destroyed by the interlacing in the enlarged image. Therefore, the vertical relationship between the lines of the two fields is not maintained, and although the information in video signal line 101 correctly follows the video signal line 100 of the original image, the video information corresponding to video signal line 100 may sometimes It is clear from FIG. 5 that the enlarged image appears before the . This results in an incorrect vertical orientation, which is quite disturbing to the viewer.

It is therefore clear that the simple method of obtaining enlarged images described above is not entirely satisfactory.

In view of the foregoing description, it is of course possible to obtain absolutely correct relationships between the lines of the magnified image using complex techniques, such as those shown in the illustration of FIG. It is clear that repetition of video information determined in both odd and even fields may be used so as not to be mixed with the information of the video line signal.

The invention therefore particularly aims to provide a method and a device for displaying enlarged images without requiring complex techniques and without distorting the vertical direction of the description.

Specifically, according to the present invention, the effects of vertical distortion are minimized in a simple way by selectively duplicating video information in the lines of the magnified image, so that it is possible to blank several lines of the magnified image. Even so,
The remaining lines appear in their correct vertical orientation. Omitting a few lines in the image is not a problem, especially since the vertical distortion is removed.

The method and apparatus according to the invention also have the advantage of facilitating special effects on enlarged images, such as displaying a format in which portions of the image are enlarged without enlarging other portions.

BRIEF DESCRIPTION OF THE DRAWINGS In order to provide a clear understanding of the invention, the invention will now be described in detail with reference to the accompanying drawings.

In one illustrative embodiment of the invention, the vertical distortion described above is resolved by blanking every fourth line in the odd fields of the enlarged image and blanking the first two lines of the four lines in the even fields. can do.

This is shown in FIG. However, displayed odd and even field lines are indicated by dots, while blanked lines are indicated by the letter B. In this embodiment, each of the three consecutive lines of the odd field replicates the same video line, and the two even video lines following each other replicate the same line from the even video field. As a result, in the enlarged image, only three lines are omitted in each group of eight consecutive lines representing the odd field video-line of the original image and the next succeeding even field video-line. Furthermore, it is clear that the technique shown in FIG. 6 preserves the correct ordering of the odd and even field information lines.

The correspondence between the original video lines and the lines of the enlarged image according to the configuration of FIG. 6 is shown in FIG.

FIG. 7 shows blanking the first two lines of the odd field in each eight-line sequence of the enlarged image;
Clearly indicates the blanking of the last field of even fields. Therefore, according to the present invention, by selectively blanking lines that have been copied multiple times in odd and even fields, it is possible to form a visually distortion-free image.

Of course, other combinations of blanking and
Lines and duplicated lines may be used to achieve the same result.

One embodiment of a structure that can be used to modify a video signal in accordance with the present invention for display on a multiple display screen is shown in FIG. In this structure, a composite video signal of normal characteristics, such as a color signal according to the NTSC specification, is
It is applied to a decoder, a synchronization signal detector and a zero check generator 50. This circuit processes the television video signal in a conventional manner and generates, for example, red, green and blue color signals R+tGi, s+, a clock signal C1, a vertical synchronization signal V5ync and a horizontal synchronization signal H3ync. The color signals Ri, Qi, 3i are fed to a plurality of individual low-pass filters 51 (three such filters are shown in the figure). A low pass filter 51 conditions the digitized signal to prevent aliasing noise. Next, the individually filtered color signal R11Gi
, Bi are supplied to a plurality of individual analog-to-digital conversion circuits (A/D) 52 (the figure shows thirteen such conversion circuits). The digitization speed is determined by the NTSG decoder, synchronization signal detector and clock generator 5o.
is determined by the clock signal C1 and is of a speed suitable for digitizing a frequency signal at the video signal frequency by conventional techniques. Of course, the clock signal C1 in the NTSG decoder, synchronization signal detection 3 and clock generator 50
It is, of course, possible to achieve this by conventional techniques.

Next, the digitized color signals Ri and Qi 113i
is applied to a plurality of memories 53. In one embodiment of the invention, a memory device for each display screen of the magnifying display device;
For example, each has 4 display screens, and 4
16 of the above illustrative examples using row-stacked display screens
Preferably, a memory device is provided. Furthermore, the memory device 5
3 are odd field color signals Ri, Q
i.

It is preferable to reach 11I in three memories that individually store B1 and three memories that individually store even field color signals Ri and Qi 13i. For a black and white display, of course, only one pair of memories is required for the odd and even fields.

The output of reading out the memory device corresponding to the display screen is transmitted through a plurality of individual analog converters (D/A) 53a,
and a plurality of individual low pass filters 54 to produce output color signals RO1GO 180, each applied to its respective display device. Therefore, in this embodiment, the output color signal RO1GO1BO of each display screen is processed by a separate analog-to-digital converter and a separate low-pass filter.Read/write control and addressing of the memory device 53 is performed by an address and clock generator 55' which supplies an address signal A1 to the memory device 53 and a clock signal C2 to the analog converter 53a. is NTSG
Vertical synchronization signal V Syn and horizontal synchronization signal H3ync from the decoder, synchronization signal detector and clock generator 50
and synchronized with clock signal C1. The operation of address and clock generator 55 is discussed in detail in the following sections.

A preferred method of writing data to and reading data from memory device 53 is shown in FIG.

In FIG. 9, the top and bottom horizontal lines indicate a composite video input signal CVin having sequential odd and even field data. In the present invention, odd field video information is written to odd field memory, and even field video information is written to even field memory.
It gets burned into the memory. The data corresponding to the odd field is read out from the odd field memory at a time delayed by one field WA after it is written.

Similarly, data corresponding to an even field is read from the even field memory one field time after it is written.

By using this double buffering technique, each memory is always being written to or read from, but not simultaneously.

The method for detecting odd and even fields is as follows:
Based on standard NTSG format. Here, the start line of one field of images occurs with an integer number (16) of vertical sync pulses followed by a horizontal sync pulse. Also, the first horizontal synchronization signal pulse corresponding to one line to be displayed is an integer (16) following the vertical synchronization signal pulse.
This occurs at a time corresponding to +1/2 horizontal line period.

Therefore, all that is required is to colort the horizontal sync pulse following the vertical sync pulse to determine whether the current video information was extracted from the odd or even field. It is.

According to a preferred embodiment of the invention, video information is stored in the memory device of each display screen according to the signal sequence to be displayed on that display screen, so that the data is stored in the odd field memory and even field memory of that display screen. can be easily read out sequentially from the column.

Of course, it is clear that other memory storage techniques employing different memory readout techniques may be used instead. However, the preferred technique is to copy the video information of the first line of the video signal into the first three columns (or equivalent) of the odd field memory after detecting the receipt of data corresponding to the odd field. , 4th
Leave the column empty. Similarly, the third part of the original video signal
The video information by line is copied into the next three columns of odd field memory, leaving the next column empty, and so on. When video information is received from an even field, the first line of video information is copied to the third and fourth columns of the even field memory, and the first two columns are left empty. Next, the second even field
Copy the video information of the video signal by line to the seventh and eighth columns of the even field memory, and
Leave the column empty. This technique is shown in FIG. Storing data in this manner allows the odd and even field memory to be read column by column to output video information for the display screen. As will be explained in detail below, the lines of the original video signal stored in each memory correspond only to the lines to be displayed on a given display screen. Therefore, when the display screens are vertically stacked in four stages, the waveform of FIG. 10 is compensated only for the top row of the display screens. Therefore, the data stored for display screens at different vertical levels needs to have different sequences of lines of the original video signal.

One arrangement that can be used to store and read video data in accordance with the present invention is shown in FIG. 11th
The figure shows a device for storing the color signals of one display screen of an enlarged image for odd and even fields. Therefore, the odd field Φ memory 70 may include three independent memories, and similarly the even field memory 71 may include three independent memories. Odd field memory 70 and even field memory 71 may each be of conventional RAM structure with address lines 72, 73 connected to minicomputer 75. In addition, the odd field memory 70 and the even field memory 71 are provided with write/read selection lines 76, 77 connected to an odd/even field detector 78 to enable the odd field memory to read the odd field. Data is written in periods, and data is read out in even field periods. Similarly, odd/even field detector 78 energizes the even field memory to write data to it during even field periods and read data to it during odd field periods of the video input signal. To this end, the odd/even field detector 78 receives a horizontal sync signal @H from line 79.
3yna, and the vertical synchronization signal vsyn, and the current field can be determined by conventional means as described above. Conventional circuits connected to the data lines of the odd field memory 70 and even field memory 71 are used to supply color signals to the memory at appropriate field periods, and to read the memory and provide playback signals to the display device. It may also include selectors 80 and 81. The select lines of selectors 80.81 are also controlled by odd/even field detector 78.

Therefore, the original color signals R, G and B on video signal line 82 are applied to selectors 80, 81, respectively. During odd field periods, the select line of selector 80 connects video signal line 82 to odd field memory 70 and output line 83 to even field memory 71. Similarly, in the even field of the original signal, the video signal on the input video signal line 82 is guided through the selector 81, and the output line 83 is connected to read the odd field memory 70.

The microcomputer 75 may be of conventional design and includes an odd field memory 70. It provides an address sequence for writing and reading even field memory 71, and further includes as inputs, for example, the output of odd/even field detector 78, horizontal synchronization signal H5VnC, vertical synchronization signal VSyn, and the analog-digital signal shown in FIG. A clock signal Cl0Ck used to control conversion is input. Therefore, the program of the microcomputer 75 is, for example, the address and clock generator 5 of FIG.
5 advances the sequence of addresses on address lines 72, 73 at the clock rate on line 84 obtained from 5.

The program in the microcomputer 75 is programmed so as to start from a predetermined line and a position on the line of the original video signal by activating the steps of the address signals in the odd field memory 70 and even field memory 71. Along with the synchronization and vertical synchronization signals, a count of the current line of the original video signal is maintained in response to the clock on line 84 as a count.

The desired starting line and position of the original video signal line are automatically determined by the program of the microcomputer 75.
It may be controlled by the IJ, or the desired value may be entered via a normal keyboard of the microcomputer 75.

To prevent the vertical distortion described above, copying the signal so that it appears at the selected memory number is
This is accomplished by sequentially addressing the desired memory columns during each color signal pulse at a rate faster than the digital rate of the signal. Similarly, horizontal signal expansion is accomplished by stepping the addressing of each line at a rate that is a multiple of the color signal pulse rate. Of course, these speeds can be changed by controlling the keyboard of the microcomputer 75 if desired.

Additionally, as shown in FIG. 11, output line 83 is provided with an attenuator 88 which is connected to odd/even field detector 78 via line 89. The purpose of the attenuator 88 is to reduce "wide area flicker" caused by uneven number of lines in each of the two fields. The field indication signal on line 89 is high during the presence of a field with a large number of non-blank lines. This field indication signal attenuates the amplitude of the RGB signal by an amount that reduces the average brightness level relative to the brightness level of a field with a small number of non-blank lines. For example, if field 1 has 3 non-blank lines and field 2 has 2 non-blank lines, then the amplitude of the RGB signal in field 1 needs to be reduced to 2/3 of its previous value. , thereby causing the three lines of field 1 whose brightness is multiplied by 2/3 to have the same average Hra as the two lines of field 2.

Although the microcomputer described constitutes one structure for obtaining the desired address sequence of the memory, it is of course possible to use other structures, such as hard-wired random logic circuits, for this purpose. is clear.

The arrangement according to the invention is particularly suitable for easily creating special effects. When changing the address of the line to be read for each displayed line (increasing to the next line in the displayed field), assume a configuration using a 4 x 4 display screen as explained above. Each of the 16 display screens will then display an image of the original and total input signals. However, when the address of the line to be read is changed every N=4 lines being displayed, each of the 16 monitors displays 1/N 1/16 of the original 2=image.

The address of the line being read can be changed at any time. When the address is changed line by line at the same position, "1/2n" of each monitor displays part of the image of the original signal and the complete input signal, and the remaining "1/2n of each monitor displays a part of the image of the original signal and the complete input signal.
1/2" will display a portion of the enlarged image. This is shown in Figure 12a. It is also possible to change from one mode to the other many times in one line. For example, as shown in Figure 12b.Furthermore, it is possible to "horizontally wipe" from simple mode to enlarged mode by moving the change point d.

This is shown in Figure 12C.

In a similar and cooperative manner, horizontal wipes may be synchronized between each monitor to occur simultaneously at one or more display screen locations.

Thus, the wipe can proceed from the leftmost edge of the entire display screen array to the rightmost edge in a gradual manner. Of course,
It is clear that other modifications and techniques may be used in a similar manner.

Additionally, "special effects" can be generated in the vertical direction by changing the address mode in synchronization with the start of a line. These are illustrated in a similar manner, for example, in FIGS. 13a, 13b and 13c.

In addition, by combining vertical and horizontal special effects,
Effects such as a diagonal wipe may also be generated. Furthermore,
Each color may or may not be wiped in a similar manner if desired. Additionally, the program may control gating or de-gating of each color signal at any point in the image, for example to create a flashing pattern. Additionally, vertical and horizontal special effects may be combined to create mosaics with or without color latching.

Although reference has been made to the display screen of a television set or receiver, in view of the invention, any conventional display device can be applied in accordance with the invention;
It will therefore be clear that the above disclosure utilizes such terms in a synonymous manner.

Although the invention has been disclosed and described with reference to a limited number of embodiments, the present invention may be described without departing from the spirit or scope of the invention.
Obviously, multiple variations and modifications are possible. It is therefore intended that the appended claims cover such changes and modifications as fall within the true spirit and scope of the invention.

[Brief explanation of the drawing]

Fig. 1 (2) is a diagram showing a display screen displaying an image; Fig. 1 0 is a diagram showing a plurality of display screens each showing an image in Fig. 1 (2); FIG. 2 is a diagram showing the line allocation of the original signal on the display array of FIG. 1(c); Figure 3 illustrates an interlaced television signal; Figure 4 illustrates the relationship between the original video signal lines and the lines of the enlarged image; and Figure 5 illustrates vertically distorted enlargement. 6 is a diagram illustrating an enlargement technique according to the present invention. FIG. 7 is a diagram further illustrating an enlarged display according to the present invention. FIG. 8 is a block diagram of a signal processing system according to the present invention. FIG. 10 is a diagram illustrating field selection according to an embodiment of the invention; FIG. 11 is a more detailed block diagram of the signal processing system of FIG. 8; FIG. 12a ~Figure 12C is a diagram showing various horizontal special effects easily achievable with the present invention; Figures 13a~13C
The figure illustrates various vertical special effects that can be easily achieved with the present invention. 50... NTSC decoder, synchronization signal detector and clock generator, 53... Memory device, 55... Address and clock generator, 70... Odd field memory, 71... Even field memory , 75... Microcomputer, 78... Odd/even field detector, 80.81.
··selector.

Claims (19)

[Claims] (1) generating a display signal from a video signal and supplying it to a monitor, displaying a partial image formed by only part of the information of the video signal on the monitor;
The video signal has video field data occurring consecutively in first and second interlaced fields of a complete image, the video data of each field corresponding to successive scan lines of that field. The display signal generation method includes the step of writing the video signal to a memory that stores at least a portion of the video line data of each field. and a reading step of reading said memory to generate said display screen, said reading step omitting reading of video line data for a determined scan line of said display screen while each said sequentially reading video line data from said memory corresponding to at least a portion of the determined scan lines of a complete image a plurality of times for a field; A display signal generation method characterized in that a relationship is maintained in the partial image. 2. The method of claim 1, wherein the writing step includes writing video information corresponding to a plurality of scan lines of each field at a plurality of first locations in the memory; 2. A method of generating a display signal, wherein said reading step comprises the step of individually reading out only those determined from said plurality of positions for each of a plurality of scan lines. (3) In the display signal generation method according to claim 1, the determined scanning line is
A display signal generation method characterized in that the fields are different. (4) The display signal generation method as claimed in claim 1, wherein the memory includes a plurality of first memory locations corresponding sequentially to a first field line of the display screen, and a second field line of the display screen. a plurality of second memory locations corresponding sequentially to the field lines, said writing step includes writing video information corresponding to the determined other lines of the first field from said first memory location to said second memory location; writing video information corresponding to the determined line of the first field forming the complete image into each of a plurality of consecutive first positions separated by at least one of the positions; Write video information corresponding to another line of the second field of the complete image into each of a plurality of consecutive second positions spaced apart from the second position by at least one other second position. and writing video information corresponding to the determined line. (5) In the display signal generation method according to claim 4, the reading step includes sequentially reading the first position and sequentially reading the second position. A display signal generation method characterized by: (6) In the display signal generation method according to claim 1, the memory includes a first field of the display signal.
a plurality of first memory locations sequentially corresponding to a second field line of the display signal; and a plurality of second memory locations sequentially corresponding to a second field line of the display signal; writing video information corresponding to the first and second fields, respectively, during the occurrence of the field; the reading step includes writing the first and second fields of the video information during the occurrence of the first and second fields; A method for generating a display signal, comprising the step of reading out video information corresponding to each of the video information. (7) A display signal generation method for enlarging an image on a display device in response to a video signal, wherein the video signal includes video field data of successively generated first and second interlaced fields; the video data of the field comprises successive video scan lines of data corresponding to successive scan lines of the field; copying video data of a selected line of each said field into each of a plurality of first locations of a memory while leaving a second location free of video data; and reading the first and second memory locations in a sequence so as to preserve the physical relationship between the video lines of the second field. (8) In the display signal generation method according to claim 13, the reading step includes reading at least one second position after reading each of the first positions of one group corresponding to the same scanning line of the video signal. A method for generating a display signal, comprising a step of reading. (9) The display signal generation method according to claim 7, further comprising the step of adjusting the relative brightness of the signal read from the memory of the field, the average brightness of the video line data of the field. A display signal generation method characterized in that: are substantially equal. (10) In the display signal generation method as set forth in claim 9, the adjusting step includes the step of attenuating the signal in the memory corresponding to the field with fewer blank lines in the image displayed on the monitor. Characteristic display signal generation method. (11) In the display signal generation method according to claim 1, the reading step is determined for each of the plurality of video lines while reading data corresponding to a given video line. A method for generating a display signal, comprising the step of modifying the read sequence of the memory by a number of times. (12) In the display signal generation method of claim 1, the reading step comprises modifying the video line data reading sequence by a number of times determined during video line reading for each of the fields. A display signal generation method comprising: (13) generating a display signal from a video signal, generating an image that includes only a portion of the image information of the video signal, and wherein the video signal is continuously displayed in first and second interlaced fields of the complete image; In a display signal generating device, the display signal generating device has video field data generated, and the video data of each field corresponds to successive scan lines of that field, and the display signal generation device includes video line data generated continuously.
The display signal generating device includes: memory means; means for supplying the video signal to the memory means and storing at least a portion of the video line data of each of the fields; and reading the memory means to generate the display signal. readout means for generating a complete image a plurality of times for each said field while omitting readout of video line data corresponding to a determined scan line of said display signal; The video line corresponding to the determined scan line of
1. A display signal generating device, comprising means for continuously reading data, and maintaining the physical relationship between the scanning lines of the first and second fields in the image described in the first aspect. (14) In the display signal generating device according to claim 13, the memory means includes first and second memories connected to receive video information corresponding to the first and second fields. respectively, the means for supplying the video signal to the memory comprises means for supplying the video signal to the first and second memories, respectively, during the first and second field periods of the video signal, and the reading means are the first of the video signals, respectively.
and means for reading out the first and second memories in a second field period. (15) The display signal generating device according to claim 13, further comprising an analog signal source and an analog-to-digital conversion means for converting the analog signal into the digital video signal. Display signal generator. (16) The display signal generating device according to claim 13, wherein the memory means comprises first and second addressable memories respectively storing video information of the first and second fields; A display signal generating device comprising address means connected to the memory for addressing a memory location. (17) In the display signal generating device according to claim 16, the addressing means addresses the memory and stores video data corresponding to the determined scanning line of the video signal in each of a plurality of locations. and means for addressing said memory to sequentially read video data from said locations, wherein said display signal is sequentially arranged with the same video information corresponding to successive lines thereof. A display signal generator characterized by containing data. (18) The display signal generating device according to claim 13, further comprising means for adjusting the relative brightness of the signal from the memory means corresponding to the field, so that the average brightness of the video lines of each field is approximately equal. A display signal generator characterized by: (19) The display signal generating device according to claim 18, wherein the adjusting means is connected to attenuate the signal from the memory means corresponding to a field having fewer blank lines in the image to be displayed. A display signal generating device characterized by comprising: means.