JPH0455516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color display control method used in a teletext receiver.

Conventional technology Teletext broadcasting transmits and receives large amounts of breaking information such as news, weather forecasts, and traffic information displayed in text and graphics in the form of packets during the vertical retrace period of a television video signal. The system extracts this image and displays it in place of the television image according to the recipient's request.

For such teletext broadcasting, a pattern transmission method was initially considered in which text information was sent in patterns, but in consideration of the advantages of improved transmission efficiency and the lower memory costs provided by recent LSI technology, code transmission was developed. The method has been moved to

In this code transmission system, character information is sent out as a code, and the receiver side performs a decoding process in which the encoded character information is converted into a bit pattern and written into a pattern memory for display. The conversion from this code to a bit pattern is
This is achieved by reading out a specific location in a read-only memory called a character generator, which stores the shapes (fonts) of various characters in the form of bit patterns of "1" or "0".

Coloring information and display control information are added to the character information in units of one character or a group of consecutive characters.
The coloring information consists of a foreground color in which the "1" portion indicates the color to be displayed and a background color in which the "0" portion indicates the color to be displayed when the aforementioned bit pattern is displayed on the screen.

This coloring information is written into the color memory at the same time as the character code is converted into a bit pattern and written into the pattern memory.

The color memory is provided to correspond to each character area of the pattern memory and is referenced during display to color the characters.

The foreground color and background color are each specified by a 5-bit entry number, and are associated with specific columns (entry addresses) in the 32 color lookup tables.

The color lookup table displays "R (red)", "G (green)", and "B" for each entry address.
(Blue)” This memory has a capacity of 4 bits each (12 bits in total).

Each 4-bit information is "R" which is the three primary colors of light.
The brightness of each of "G" and "B" is defined in 16 levels, and each
"R" specified for one of 16 levels of brightness
By combining "G" and "B", any of 4096 colors can be expressed.

The display control information includes functions such as flashing, which causes a certain character or group of characters to blink at a predetermined period, and concealing, which displays hidden characters at the recipient's request.

The concealment function is used in quizzes, educational programs, etc., where answers are hidden until requested by the viewer.

Similarly, this display control information is written into the attribute memory at the same time as the character code is converted into a bit pattern and written into the pattern memory.

The attribute memory is a memory provided to correspond to each character area of the pattern memory and is referenced during display to realize character display control.

Normally, when a character converted into a bit pattern is displayed on the screen, the foreground color is always referred to for the "1" portion of the pattern memory.

However, if flushing is specified for a certain character, the foreground color and background color are alternately referenced at a predetermined period for the "1" portion of the pattern memory.

Additionally, if concealment is specified for a certain character, the background color is initially referred to for the "1" part of the pattern memory, and the original foreground color is changed at the request of the information person. Referenced.

Therefore, a teletext receiver has one screen worth of
A pattern memory for developing shape information, a color memory for developing coloring information, a color lookup table for actually determining display colors, and an attribute memory for developing display control information are required.

In teletext, a geometric figure function is defined as one of the figure display functions, as it is a desirable function for future development.

In geometric figures, points, straight lines, rectangles, polygons, and circles are drawn by specifying coordinates on the screen, and the figure is displayed by a combination of one or more codes that specify this drawing. be exposed.

Coloring of geometric figures is achieved in 1×1 pixel units by a combination of a bitmap memory and a color lookup table.

Bitmap memory is a display memory that has a depth of 5 bits for each pixel, and this 5-bit depth information allows it to be associated with a specific column (entry address) of 32 color lookup tables. .

In this way, pixels on the bitmap memory are colored and displayed in 16 out of 4096 colors according to the contents of the associated color lookup table.

Therefore, a teletext receiver equipped with a geometry function requires one screen's worth of bitmap memory in addition to one screen's worth of pattern memory, color memory, color lookup table, and attribute memory.

In addition, in the teletext broadcast mentioned above, only when the information of each 4 bits of "R", "G", and "B" in the color lookup table takes a specific value, "the information of each 4 bits is The three primary colors “R” and “G”
The brightness of each "B" is defined in 16 levels. It stipulates that special indications that cannot be stipulated under the principle of ``can be made exceptionally.''

In other words, if the information for "R", "G", and "B" are all "0000", in principle, "R", "G", and "B" will be the darkest, so "black" will be displayed. In this case, "transparent" will be displayed as an exception, and if the information of each 4 bits of "R", "G", and "B" are all "0111", as a general rule, "R", "G" will be displayed. "B"
The brightness is evenly reduced to half on both sides, resulting in a fairly white or "gray" display, but in this case, a "shadow" display is exceptionally performed only in certain cases.

Problems to be Solved by the Invention The conventional teletext receiver equipped with the geometry function described above has a pattern memory for one screen,
In addition to the color lookup table and attribute memory, a bitmap memory for one screen is required, so there is a problem that the display memory capacity becomes large.

An object of the present invention is to reduce the display memory capacity of a teletext receiver equipped with a geometry function, so that the display memory can be reduced to just one screen's worth of bitmap memory and color lookup table. , conventional pattern memory, color memory and color lookup table,
The coloring and display control functions realized by attribute memory, including exceptional special display functions,
Bit map memory and color lookup
The purpose is to provide a method to achieve this at the table.

Means for solving the structural problems of the invention The coloring display control method of the present invention which solves the problems of the prior art described above registers a color in a broad sense consisting of a coloring value and a coloring change attribute in a coloring display management table. A coloring control process that registers the coloring value of the color in a broad sense and an identification code indicating its display method such as "transparent" in any free area of the color lookup table, and a coloring control process that registers the coloring value of the color in a broad sense and an identification code indicating its display method such as "transparent", and The coloring value of the color that includes the coloring change attribute is changed to the above color according to this coloring change attribute.
By executing display control processing that changes on the lookup table in parallel, large-capacity attribute memory is replaced with a small-capacity coloring display management table, greatly reducing the memory capacity for coloring and display control. It is composed of

Note that the term "color in a broad sense" is used here for convenience of explanation. "Color in a broad sense" used here refers to the color expressed on the screen, such as "full brightness yellow for positive phase flashing" and "full brightness red for concealing", as well as the coloring change attributes of flashing and concealing. We have decided to treat the combination of these specifications as a color in a broad sense, and call it a ``color in a broad sense,'' including cases where there is no coloring change attribute, such as ``full brightness yellow without flashing or concealment.'' It is.

Furthermore, in contrast to "colors in a broad sense," colors without coloring change attributes are particularly referred to as "colors in a narrow sense."
In the following explanation, the words "color in a broad sense" and "color in a narrow sense" will be used for convenience of explanation.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

Embodiment FIG. 1 shows a teletext receiver to which a color display control method according to an embodiment of the present invention is applied.
FIG. 2 is a block diagram showing the configuration of the minimum necessary parts for explaining this embodiment.

This receiver includes a central processing unit (CPU) 1, a work RAM 2, a display bitmap memory 3,
Color lookup table 4, system
It includes a bus 5, a character generator 6, a CRT controller 7, a program ROM 8, a data extraction circuit 9, a line buffer 10, and a D/A converter 11.

The data extraction circuit 9 extracts character information that appears during the vertical blanking period of the television signal supplied from the receiver, performs error correction, and clock reproduction. The extracted character information is line buffer 1
0 and the system bus 5 to the central processing unit 1.

When the central processing unit 1 receives the coded character information, it converts it into a corresponding pattern using the character generator 6, and stores the foreground color and background color of the pattern in the pattern writing position in the display bitmap memory 3. Write. These foreground colors and background colors are registered in a coloring display management table created in the work RAM 2 as colors in a broad sense including attributes. Every time it becomes necessary to use an unregistered color among the broad colors that include attributes, the central processing unit 1 registers it in the free space of the coloring display management table in the work RAM 2, and also stores the coloring value in the color display management table. Register in an empty entry in lookup table 4.

Figure 2 shows color lookup table 4.
FIG. 2 is a conceptual diagram showing the configuration of.

In this color lookup table 4, a 12-bit coloring value is registered in each of 32 entries specified by a 5-bit entry number. The entry number consists of the upper 1 bit of the palette number (P.No.) and the lower 4 bits of the color map row address (CMLA).
It consists of Each 12-bit coloring value is 4
It is composed of bit R, G, and B gradation signals.

In addition, in the conventional method, each entry and the coloring value registered there are fixed on a one-to-one basis, and if a predetermined signal instructing to change the entry contents is not sent, the entry number [08] and the coloring value registered therein are fixed. [OF]
For each entry, "transparent color" with all "0" for R, G, and B, and "half-bright white (gray)" with "0111" for R, G, and B are fixedly registered. It's getting old. Characters specified to be displayed in a transparent color are displayed in the same color as the raster color, which can also be called the background color of the entire character screen. Half-volatile white is a special color in teletext broadcasting, and when half-volatile white is specified as the background color in super display mode, where the text screen is displayed superimposed on the television screen, , this half-brightness white is defined to perform a shadow function to reduce the level of the television video signal around the characters displayed by the foreground color.

In the method of the present invention, the entries and stored coloring values on the color lookup table 4 are not fixed, and each entry is assigned an entry number with an arbitrary coloring value that becomes necessary as the display state progresses. are dynamically registered in increasing order. Therefore, whether the coloring value of all "0" is used as the original "black" or "transparent" is determined by the 1-bit display method, and also for hardware control to perform shadow display. sign is 1
A total of 2 bits of identification code is added after the coloring value based on 12-bit R, G, and B gradation signals. This identification code is used as the color indicated by the corresponding entry in color lookup table 4 according to the coloring value of the 12-bit R, G, B gradation signal stored in that entry. “00” if “transparent”
When used as a "shadow display", it is "01", and when used as a "shadow display", it is "10".

FIG. 3 is a conceptual diagram showing the structure of a colored display management table formed in the work RAM 2. As shown in FIG.

Every time the central processing unit 1 starts receiving character information for one screen, it clears each column of this coloring display management table, and then clears the attributes from the top row to the bottom row in the order in which the need for registration occurs. Register colors in a broad sense including .

The first column of each row displays the presence/absence of registration.
A bit flag is prepared. In the next column, 1-bit flags indicating the presence/absence of flushing are prepared separately for the case of normal phase flushing and the case of reverse phase flushing. The phases of blinking are shifted by 180 degrees between the normal phase and the reverse phase.
A 1-bit flag indicating presence/absence of concealment is provided in the next column. In the next two columns, the foreground color and background color are written as 5-bit entry numbers. These entry numbers are conventional color lookup table entry numbers specified in the received signal from the center station.
In this embodiment, this conventional correspondence between entry numbers and coloring values is registered in a correspondence table in the work RAM 2.

The next two columns are filled with 12-bit foreground and background color values, respectively. The 12-bit foreground color and background color are each displayed as a combination of 4-bit R, G, and B gradation signals. In the last column, a 1-bit identification flag indicating whether the broad color registered in the corresponding row is the foreground color or the background color is registered.

The central processing unit 1 performs a coloring control process that registers a broad color that has become necessary for coloring in a coloring display management table, and registers a coloring value of this broadly defined color in a color lookup table, and a coloring display management table. Display control processing is executed in parallel to change the coloring value of a color that includes a coloring change attribute among the broadly defined colors registered in the color lookup table in accordance with the coloring change attribute.

FIG. 4 is an example of a display screen for explaining the content of the coloring control process by the central processing unit 1 and the display control process based on the timer interrupt and concealment release interrupt.

In this display screen, "This is" is displayed in a "yellow" coloring value, followed by "TV teletext" which is also flashing in a "yellow" coloring value, and then "TV teletext" is also flashed in a "yellow" coloring value. This is followed by "This is an experimental broadcast." displayed as a value. Furthermore, in the following example, "this" is displayed with a "red" coloring value, "new" is concealed with a "red" coloring value, and "broadcast..." is displayed with a "red" coloring value. be.

For convenience of illustration, both "yellow" and "red" above are assumed to be at full brightness, and in Fig. 4, "full brightness" is used.
The modifier is omitted.

FIG. 5 shows the arrangement of control codes and character codes that the central processing unit 1 should receive when displaying the display screen of FIG. 4. The coloring specification code in the control code is the coloring value and color lookup.
Assuming that table entry numbers have a one-to-one correspondence, a color lookup table entry number for such a conventional receiver is sent.

When the central processing unit 1 receives a foreground color specification code that specifies the foreground color as "full brightness yellow" at the start of the screen, it causes the built-in foreground color holding register to hold the corresponding entry number "03". . This entry number "03" is the conventional entry number when the coloring value and its storage entry are fixed, and for convenience of explanation, it is to be distinguished from the actual entry number in the color lookup table 4. , the former is expressed in brackets "", and the latter is expressed in brackets [ ].

Subsequently, the central processing unit 1 stores the entry number "0A" of the predetermined background color value (in this example, "half-bright green") that is to be selected if no background color value is specified. Store it in the background color holding register.

When the central processing unit 1 subsequently receives the character code of the hiragana "ko", it determines whether the entry number "0A" held in the background color holding register is registered in the colored display management table. In this example, the entry number "0A" is unregistered, so the central processing unit 1 registers "0A" in the background color entry number column of the first empty row [00] of the coloring display management table, and "Half-brightness green" corresponding to the entry number is read from the correspondence table in the work RAM 2 and registered in the background color value column. Subsequently, the central processing unit 1 sets "0" to indicate that the registered coloring value is the background color in the foreground color/background color identification flag column, and finally sets a flag to indicate whether or not it is registered. Set it to the registered “1”. Next, the central processing unit 1 assigns a coloring value of half-brightness green to the first empty entry [00] of the color lookup table 4, and an identification code “00”.
Register.

When this background color registration is completed, the central processing unit 1 determines whether the entry number "03" held in the foreground color holding register is registered in the colored display management table. In this example, the entry number "03" is unregistered, so the central processing unit 1 registers "03" in the foreground color entry number column of the next empty row [01] in the coloring display management table, and "Full brightness yellow" corresponding to the entry number is read from the correspondence table in the work RAM 2 and registered in the foreground color value column. Subsequently, the central processing unit 1 sets "1" to indicate that the coloring value registered in the foreground color/background color identification flag column is the foreground color.
, and finally set the flag that indicates whether or not it is registered to "1", which indicates that it is already registered. Subsequently, the central processing unit 1 registers the coloring value of "full brightness yellow" and the identification code "00" in the next empty entry [01] of the color lookup table 4.

When the registration of the background color and foreground color is completed, the central processing unit 1 stores the background position and each dot position of the corresponding dot pattern generated by the character generator 6 in the display bitmap memory 3. , the entry numbers [00] and [01] of the color lookup table 4 are written, and the coloring control processing for the hiragana "ko" is completed.

When the central processing unit 1 receives the subsequent hiragana ``re'', the entry numbers ``0A'' and ``03'' held in the background color holding register and foreground color holding register are already set to 〔00'' on the colored display management table. ] and [01] rows, the data generated by the character generator 6 is stored in the display bitmap memory 3 without being registered in the color display management table and color lookup table 4. Entry numbers [00] and [01] of color lookup table 4 are assigned to the background position of the corresponding dot pattern and each dot position, respectively.
is written, and the coloring control process for the hiragana "re" is completed. The central processing unit 1 performs the same coloring control process for the subsequent hiragana "ha" as the coloring control processing for the hiragana "re".

Next, when the central processing unit 1 decodes the control code for starting positive phase flushing, it sets "1" in the built-in flushing flag register. When the central processing unit 1 receives the katakana "te" next,
A search is made to see if "full brightness yellow" held in the foreground color holding register is registered on the coloring display management table as a color in a broad sense that includes the attribute of flashing. In this example, since "full brightness yellow" in the broad sense, which includes the attribute of flashing, is not registered on the colored display management table, the central processing unit 1 writes the following blank line [02] in the colored display management table.
Write the background color entry number "0A" and the foreground color entry number "03". Continuing with central processing unit 1
refers to the corresponding table in work RAM 2, writes the background color value "half brightness green" and the foreground color value "full brightness yellow" to the corresponding row of the color display management table, and displays the presence/absence of positive phase flashing. flag, foreground/
The background identification flag and the flag indicating presence/absence of registration are set to "1". Next, central processing unit 1
registers the coloring value "full brightness yellow" used as the foreground color of positive phase flushing and the identification code "00" in the next empty entry [02] of the color lookup table 4.

When this registration is completed, the central processing unit 1 causes the character generator 6 to generate the katakana ``te'', and instructs the display bitmap memory 3 to color each dot position of this character pattern and its background position.・Luckup table 4
Write the entry numbers [02] and [00]. When the central processing unit 1 receives the subsequent katakana "Re", it checks whether "full brightness yellow" held in the foreground color holding register is registered on the coloring display management table as a color in a broad sense that includes the flushing attribute. Search for whether or not. In this example, the broad color "full brightness yellow", which includes the attribute of flashing, has already been registered in the [02] row of the color display management table, so the central processing unit 1 uses the color display management table and the color lookup table. 4, the character generator 6 generates the katakana character ``re'', and the display bitmap memory 3 displays a color at each dot position of this character pattern and its background position.・Entry numbers of Luckup Table 4 [02] and [00]
Write. The central processing unit 1 also converts the subsequent katakana “bi” into kanji “bun”, “ji”,
The above “re” also applies to “multiple”, “heavy”, “ho”, and “send”.
Exactly the same coloring control processing as in the case of is performed.

When the central processing unit 1 decodes the positive phase flushing end code, it returns the built-in flushing flag register to "0". When the central processing unit 1 subsequently receives the hiragana "no", the content of the flushing flag register is "0", the content of the background color holding register is "0A", and the content of the foreground color holding register is "03'', a search is made to see if such a narrowly defined color is registered in the coloring display management table. In this example, the corresponding background color and foreground color are registered in the [00] and [01] rows of the colored display management table, respectively, so the central processing unit 1 uses the colored display management table and the colored display management table.
Color lookup is performed in the display bitmap memory 3 at each dot position of the corresponding character pattern generated by the character generator 6 and at its background position, without making any new registration in the lookup table 4.・Write the entry numbers [01] and [00] of table 4.

The central processing unit 1 processes the following kanji ``jitsu'', ``ken'',
``Ho'', ``Shoku'', hiragana ``de'', ``su'', and comma ``.''
Also, the same coloring control process as in the case of the flat plate name "no" is performed.

Next, when the central processing unit 1 decodes the foreground color specification code that specifies the foreground color as "full brightness red,"
Rewrite the contents of the foreground color holding register to the corresponding entry number "02".

When the central processing unit 1 subsequently receives the hiragana "ko", it detects that the entry number "02" held in the foreground color holding register is not registered in the colored display management table, and updates the colored display management table. Write the foreground color entry number "02" in the next blank line [03] line. Subsequently, the central processing unit 1 writes "full brightness red", which is the new foreground color, in the foreground color value column. Next, the central processing unit 1 sets the foreground color/background color identification flag and the registration presence/absence flag at the beginning of the [03] row of the colored display management table to "1", and then sets the next color in the color lookup table 4. Register the coloring value of "full brightness red" to be used as the foreground color and the identification code "00" in the empty entry [03].

Next, the central processing unit 1 generates a bitmap for display.
The entry number [03] of the color lookup table 4 is stored in the memory 3 for each dot position of the character pattern of the hiragana "ko" generated by the character generator 6 and its background position.
and write [00]. The central processing unit 1 stores the subsequent hiragana "no" in the character generator 6 in the display bitmap memory 3 without newly registering it in the color display management table and color lookup table 4. The entry numbers [03] and [00] of the color lookup table 4 are written in each dot position and the background position of the character pattern of the hiragana "no" generated in step.

When the central processing unit 1 next decodes the conceal start control code, it sets "1" in the built-in conceal flag register. After that, when the central processing unit 1 receives the kanji "new", it checks whether "full brightness red" held in the foreground color holding register is registered on the coloring display management table as a color in a broad sense that includes the attribute of concealment. Search for whether or not. In this example, "full brightness red" in the broad sense, which includes the attribute of concealment, is not registered in the coloring display management table, so the central processing unit 1 writes the following in the next blank line [04] in the coloring display management table. Write the background color entry number "0A" and the foreground color entry number "02". The central processing unit 1 continues to use the work RAM
Referring to the corresponding table in 2, write the background color value "half brightness green" and the foreground color value "full brightness red" in the corresponding row of the coloring display management table, and set the flag to display the presence/absence of concealment, foreground/ Set the background identification flag and the flag indicating registration presence/absence to "1", and set "half-brightness green" to be used as the conceal background color to the next empty entry [04] in color lookup table 4. Register the coloring value and identification code “00”.

When this registration is completed, the central processing unit 1 causes the character generator 6 to generate the kanji ``Shin'', and in the display bitmap memory 3, colors are added to each dot position of this character pattern and its background position.・Write the entry numbers [04] and [00] of Lookup Table 4. When the central processing unit 1 receives the subsequent hiragana "shi",
A search is made to see if "full brightness red" held in the foreground color holding register is registered on the coloring display management table as a color in a broad sense including the attribute of concealment. In this example, since the broad color "full brightness red" that includes the attribute of concealment has already been registered in the [04] row above the coloring display management table, the central processing unit 1 uses the coloring display management table and color lookup. The katakana ``shi'' is added to the character generator 6 without making a new registration on the table 4.
is generated, and entry numbers [04] and [00] of the color lookup table 4 are written into the display bitmap memory 3 at each dot position of this character pattern and its background position, respectively. The central processing unit 1 performs the same coloring control process for the subsequent hiragana "i" as in the case of the hiragana "shi".

When the central processing unit 1 next decodes the concealment end code, it returns the built-in concealment flag register to "0". When the central processing unit 1 continues to receive the kanji character "ho", the contents of the flushing flag register and the concealing flag register are "0", and the contents of the background color holding register are "0A".
Since the content of the foreground color holding register is "02", a search is made to see if such a narrowly defined color is registered in the colored display management table. In this example, the corresponding background color and foreground color are registered in rows [00] and [03] of the color display management table, respectively, so the central processing unit 1 registers the color display management table and color lookup table. 4, the display bitmap memory 3 is given a color image at each dot position and its background position of the corresponding character pattern ``HO'' generated by the character generator 6.
Write the entry numbers [03] and [00] in Lookup Table 4. The central processing unit 1 also performs the same coloring control process as in the case of the above-mentioned "release" for the subsequent "transmission", "de", "ha", . . . .

During the coloring control process, the central processing unit 1
When the foreground color/background color transparent (CMLA8) code is decoded with a transparent color specified, that is, palette 0 is specified, the coloring value of all “0” for R, G, and B is determined by referring to the correspondence table in work RAM 2. and the identification code "01" are registered in the next vacant entry on the color lookup table 4. Further, when the central processing unit 1 decodes the designation of half-brightness white, it registers the coloring value of "0111" and the identification code "10" for R, G, and B in the empty entry on the color lookup table 4.

Therefore, each row of the colored display management table and each entry of the color lookup table 4 has a one-to-one correspondence, and the required number of rows of the colored display management table is the same, 32 rows.

The combinations of attributes are "No attribute specified", "Normal phase flushing specified, no concealment specified", "Reverse phase flushing specified, no concealment specified",
"No flashing specified, concealment specified"
There are 6 ways: ``with normal phase flushing specification, with concealment specification'' and ``with reverse phase flushing specification, with concealment specification'', so 32 x 6 =
There can be 192 broad colors. however,
Since the number of broadly defined colors used on one screen is approximately 32 at most, in this embodiment, the number of rows in the coloring display management table and the number of entries in the color lookup table that are dynamically updated on a per screen basis are as follows: ,
As mentioned above, 32 each is sufficient.

The central processing unit 1 performs the following coloring control process in parallel with the coloring control process, which consists of registering colors in a broad sense in the coloring display management table in the work RAM 2 and registering coloring values in the color lookup table 4. Executes display control processing.

The central processing unit 1 starts a flashing display control process based on a timer interrupt of a predetermined period determined for flashing, and sets a flag indicating presence/absence of positive phase flashing to "1" from the colored display management table. The content of the color lookup table 4 having the same entry number as the row number is changed from the foreground color to the background color. In addition, the central processing unit 1
searches the color display management table for a broad color for which the flag indicating the presence/absence of reverse phase flashing is set to "1", and searches for the color lookup with the same entry number as that row number.
Change the contents of the entry in Table 4 from the background color to the foreground color.

In the next flashing display control process based on a timer interrupt, the central processing unit 1 changes the contents of the color lookup table 4 from the background color to the foreground color for colors related to normal phase flashing in a broad sense, and changes the contents of the color lookup table 4 from the background color to the foreground color for the colors related to positive phase flashing. Regarding the related colors in a broad sense, the contents of the color lookup table 4 are changed from the foreground color to the background color.

In this way, by the flashing display control process based on the timer interrupt, the foreground color and the background color are alternated at the flashing period, and the corresponding character or character group is flashed at a predetermined period (1 second in teletext).

In addition, when the central processing unit 1 receives a concealment cancellation command issued by the viewer of the screen via the keyboard or remote control pad, the central processing unit 1 starts concealment cancellation interrupt processing and displays the presence/absence of concealment from the colored display management table. The color in the broad sense whose flag is set to "1" is searched for, and the contents of the color lookup table 4 having the same entry number as the row number are changed from the background color to the foreground color. As a result, characters or character groups that were hidden in the background color appear on the display screen in the foreground color.

Above, we have exemplified a configuration in which a 2-bit identification code is added to a 12-bit coloring value, but in addition to adding only a 1-bit identification code that indicates whether it is black or transparent, the coloring value is A configuration may be adopted in which shadow display is performed by adding hardware that detects that R, G, and B are all "0111".

In addition, although we have illustrated a configuration in which columns for registering foreground color values and background color values are provided in each row in the coloring display management table, by removing these columns, when performing display control processing, The configuration may be such that a correspondence table in the work RAM 2 is referred to based on the read foreground color entry number and background color entry number, and the corresponding foreground color value and background color value are written on the color lookup table 4.

Furthermore, although a configuration has been illustrated in which the central processing unit 1 performs the coloring control process and the display control process, the CRT controller 7 may share the display control process.

Effects of the Invention As explained in detail above, the coloring display control method of the present invention can perform coloring and display control functions that were conventionally realized by pattern memory, color memory, color lookup table, and attribute memory, with exceptions. The display memory of a teletext receiver equipped with a geometry function is realized by a bitmap memory and a color lookup table, including special display functions.
Since it can be configured with only a bitmap memory for a screen and a color lookup table, the required display memory capacity can be greatly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the minimum necessary parts for explaining this embodiment of a teletext receiver to which a color display control method according to an embodiment of the present invention is applied, and FIG. 1 is a conceptual diagram showing the configuration of the color lookup table 4, FIG. 3 is a conceptual diagram showing the configuration of the coloring display management table created in the work RAM 2 of FIG. 1, and FIGS.
The figure shows an example of a display screen illustrated to explain the coloring and display control processing by the central processing unit 1 in FIG. FIG. 1...Central processing unit, 2...Work RAM, 3
...Display bitmap memory, 4...Color lookup table, 6...Character generator, 7...CRT controller, 8
...Program ROM.

Claims (1)

[Scope of Claims] 1. A coloring display management table that registers a color in a broad sense consisting of a coloring value of at least one of the foreground color and background color of a displayed character, and a coloring value changing attribute of flashing, concealing, or similar coloring values of this displayed character. and a color value section and an identification code section for hardware control to realize special display.
A coloring display control method for a teletext receiver comprising a lookup table and a bitmap memory for storing an entry address of a coloring value in the color lookup table for each pixel, the color in the broad sense coloring control processing that registers the corresponding coloring value and special display identification code in the color lookup table, and coloring the broad colors registered in the coloring display management table. 1. A coloring display control method for a teletext receiver, comprising: a display control process of changing a coloring value of a color lookup table according to a value and a coloring change attribute. 2. The coloring display control method for a teletext receiver according to claim 1, wherein the contents of the coloring display management table and the color lookup table are updated for each screen.