JP2014035453A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the display of a vertical character string in a line buffer type image processor.SOLUTION: A processing character number, a processing line number and a display/non-display determination flag are introduced as attribute data of a character string. The display/non-display determination flag is set to 1 (that is, a value indicating being a display object) with the arrival of the position VD of a horizontal scan line at a display position Y of a vertical character string as a trigger, and subsequently, a part shown by the processing line number of a character shown by the processing character number is drawn in each time the horizontal scan line is updated. In parallel with this, the value of the processing line number is incremented by one each time the horizontal scan line is updated, and the processing character number is incremented by one and the processing line number is reset to 0 with the arrival of the value of the processing line number at a character size -1, as a trigger.

Description

  The present invention relates to an image processing apparatus that draws image data and displays it on a display such as a liquid crystal display by using a line buffer having a storage capacity for one line.

  As is well known, display control of still images and moving images on a display device includes drawing processing for writing image data of still images and moving images into a buffer according to a drawing application, and display processing for reading out image data in the buffer and displaying it on the display device. This is realized by proceeding in parallel. As an image processing apparatus for performing such drawing processing and display processing, a frame buffer type image processing apparatus having a frame buffer for storing image data for one frame and a line buffer for storing image data for one line There is a line buffer type image processing apparatus including Since the line buffer type image processing apparatus requires less storage capacity of the buffer to which the image data is written compared to the frame buffer type image processing apparatus, it is suitable for downsizing, and an in-vehicle image display system (for example, It is suitable for construction of a system that requires space saving, such as a system that realizes meters such as a speedometer by image display). For example, Japanese Patent Application Laid-Open No. H10-228707 discloses a document related to a line buffer type image processing apparatus.

JP 2005-215252 A Japanese Patent Laid-Open No. 03-184182

  Conventionally, the display device is generally installed in such a manner that the vertical scanning direction is the vertical direction (vertical direction) and the horizontal scanning direction is the horizontal direction. However, in recent years, it has become increasingly common to install the display device by rotating it 90 degrees counterclockwise so that the vertical scanning direction is the left-right direction and the horizontal scanning direction is the up-down direction. For example, in the above-described in-vehicle image display system, it is necessary to install a display device on the driver's seat side of the dashboard. However, since the installation space is limited, it is often necessary to install the display device vertically. . Hereinafter, a display arranged so that the vertical scanning direction is the vertical direction (vertical direction) and the horizontal scanning direction is the left-right direction is referred to as a “horizontal display”, which is rotated 90 degrees counterclockwise. The installed display is called “vertical display”. A display installed by rotating the “horizontal display” 90 degrees clockwise may be referred to as a “vertical display”.

  The image displayed on the display unit is configured by combining a number of display elements such as symbols such as sprites, character strings, and lines. As shown in FIG. 4A, the display of the character string on the horizontal display is realized by displaying the fonts of the characters constituting the character string side by side in the horizontal scanning direction. On the other hand, when displaying a character string on a vertical display, as shown in FIG. 4B, as a font for each character constituting the character string, in order to facilitate reading of the character string. It is necessary to display fonts obtained by rotating the one shown in FIG. 4A by 90 degrees clockwise (that is, fonts whose character height direction matches the horizontal scanning direction) in the vertical scanning direction. Hereinafter, as shown in FIG. 4A, a character string formed by arranging fonts of constituent characters in the horizontal scanning direction is referred to as a “horizontal character string”, and as shown in FIG. A character string formed by arranging the fonts in the vertical scanning direction is called a “vertical character string”. In the following, a font for configuring a horizontal character string is referred to as a “horizontal character string font”, and a font configuring a vertical character string is referred to as a “vertical character string font”.

  As described above, the line buffer type image processing apparatus is suitable for the construction of a system requiring high space saving. However, in this type of system, there are many restrictions on the installation space of the display. In many cases, it is required to correspond to the vertical placement. In order to support the vertical placement of the display device, it is necessary to have a function of displaying a vertical direction character string. However, a line buffer type image processing apparatus having a function of displaying a vertical direction character string has been conventionally used. It was not proposed.

  The present invention has been made in view of the above problems, and a vertical character string is provided in an image processing apparatus that draws image data and displays it on a display using a line buffer having a storage capacity for one line. An object is to provide a technique that enables display.

  In order to solve the above problems, the present invention stores a line buffer for storing image data representing an image for one scan line on a display device, and attribute data indicating a display mode of a character string to be displayed on the display device. One scan line using a general purpose table, a memory interface that reads font data of characters instructed to be read from a memory that stores font data representing fonts of various characters, and font data read from the memory Image data generation unit that generates image data for each minute and executes drawing processing to be written in the line buffer, and specifies characters across horizontal scan lines in each horizontal scanning period with reference to attribute data stored in the general-purpose table And instructing the image data generation unit to execute a drawing process for the corresponding character. The character string is a vertical character string in which the height direction of each character constituting the character string matches the horizontal scanning direction, and the characters are arranged in the vertical scanning direction, The controller updates the parameter indicating the character across the horizontal scan line and the number of lines of the character across the horizontal scan line when the horizontal scan line extends across the vertical character string. An image processing apparatus is provided that instructs the image data generation unit to execute a drawing process for a line indicated by the parameter of the character indicated by the parameter.

  More specifically, when the vertical character string attribute data is stored in the general-purpose table, the controller sets the first and second parameters in a register or the like in association with the vertical character string. Here, the first parameter is a parameter indicating a character straddling the horizontal scan line when the horizontal scan line straddles the vertical character string corresponding to the first parameter. Is a parameter indicating which line of the character indicated by the first parameter the horizontal scan line is straddling. The initial value of the first parameter is a value indicating the first character of the vertical character string, and the initial value of the second parameter is a value indicating the first line of the first character. In the present invention, each time the horizontal scan line is updated, the first and second parameters are updated, and the image data of the font of each character constituting the vertical character string is one line in order from the first character. Rendered in the line buffer. Thereby, the display of the vertical direction character string on the display is realized. The initialization of the first and second parameters may be performed by the host CPU when writing the vertical direction character string attribute data to the general-purpose table, or when the image processing apparatus is initialized. You can go. Patent Document 2 describes a vertical writing layout of character strings, but does not disclose display control of vertical character strings in a vertical display device, and is a technique completely different from the present invention.

  In a more preferred aspect, the memory stores vertical character string font data representing a font in which the height direction of the characters is matched with the horizontal scanning direction. The attribute data of the vertical character string includes: It is specified that the font data for the vertical character string is used for character drawing. According to such an aspect, when each character constituting the vertical character string is displayed, the font for the horizontal character string is rotated 90 degrees clockwise and used in comparison with the aspect used. Thus, the amount of calculation processing is reduced, and it is possible to avoid a decrease in drawing performance and an increase in the scale of the calculation circuit.

  In another preferred embodiment, the font data stored in the memory is compressed and encoded, and the decoding is performed by decoding the font data read from the memory and supplying the decoded data to the image data generation unit. It further has a portion. According to such an aspect, it is possible to reduce the capacity of the memory for storing various font data, and to save the space of the entire image display system.

It is a figure which shows the structural example of the image display LSI100 of embodiment of this invention. It is a figure for demonstrating the attribute data of a character string. 6 is a diagram for explaining the operation of the image display LSI 100. FIG. It is a figure for demonstrating the display mode of the character string in a display.

(A: Configuration)
FIG. 1 is a block diagram showing a configuration of an image display system including an image display LSI (Large Scale Integrated circuit) 100 which is an embodiment of an image processing apparatus according to the present invention. In FIG. 1, in order to facilitate understanding of the functions of the image display LSI 100, a host CPU 201 connected to the image display LSI 100, an LCD (Liquid Crystal Display) 202, and a ROM 203 are shown together with the image display LSI 100. Has been. The image display system shown in FIG. 1 is an in-vehicle system that is mounted on a vehicle such as a passenger car and displays character information representing an image such as a speedometer or traffic information, and the LCD 202 is provided in a driver seat portion of a dashboard of the vehicle. It is placed vertically.

  The host CPU 201 is a processor that controls the image display system shown in FIG. An image for one frame displayed on the LCD 202 under the control of the host CPU 201 is configured by combining symbol parts, character strings, and lines called sprites. The host CPU 201 supplies commands and data for displaying sprites, character strings, and lines on the LCD 202 to the image display LSI 100. The ROM 203 stores compressed image data for various sprites and fonts of various characters constituting the character string, and compressed alpha data used for alpha blending. Although details will be described later, in the present embodiment, a plurality of pixels preceding the pixel to be decoded (for example, three pixels on the left, upper left, and immediately above in the case of a sprite) as compression encoding methods such as sprites and fonts. A compression encoding method that requires the decoding result is adopted.

  The image display LSI 100 is a line buffer type image processing apparatus that displays an image on the LCD 202 in accordance with commands and data given from the host CPU 201. As shown in FIG. 1, the image display LSI 100 includes a CPU interface (indicated as “CPU I / F” in FIG. 1) 101, a color palette storage unit 102, a general-purpose table 103, a register 104, a controller 105, ROM interface (denoted as “ROM I / F” in FIG. 1) 106, decoding unit 107, image data generation unit 108, image output unit 109, clock generation unit 110 that supplies an operation clock to these units, have.

  The CPU interface 101 is an interface that receives commands and data supplied from the host CPU 201 and supplies the commands and data to related units in the image display LSI 100. The color palette storage unit 102 is a circuit that stores color palette data representing a color palette when the image display LSI 100 is operated in the color palette mode. The color palette mode is an operation mode in which a color image is expressed by a predetermined number of colors (for example, 256 colors) out of 24 bit (or 16 bit) colors, for example, and the color palette data specifies those colors. It is data to be. The general-purpose table 103 serves as an attribute data storage unit that stores attribute data supplied from the host CPU 201 via the CPU interface 101. The register 104 is a circuit that stores various control data for sprite display and the like. In the present embodiment, the color palette storage unit 102, the general-purpose table 103, and the register 104 are provided separately, but these roles may be realized by assigning storage areas in one volatile memory.

  The attribute data is data indicating the display mode of the sprites and character strings that constitute the image displayed on the LCD 202 in each vertical scanning period (in what position on the screen and in what form). The attribute data is supplied from the host CPU 201 for each vertical scanning period, and is stored in the general-purpose table 103 for each image component such as a sprite or a character string by the CPU interface 101.

  FIG. 2 is a diagram illustrating an example of storing character string attribute data in the general-purpose table 103. The attribute data of the character string includes data representing the display mode of the entire character string (such as the display position of the character string), data indicating each character constituting the character string, and the font type used for displaying each character. included. In FIG. 2, in the area where the addresses are LYSA to LYEA, the character string included in the image to be displayed on the LCD 202 is data indicating the display mode of the entire character string (each of layers # 0, # 1, and # 2 in FIG. 2). Are stored for several minutes.

  For example, layer # 0 shown in FIG. 2 is data indicating a display mode of the character string “ABCDE” shown in FIG. This layer # 0 includes the display position of the character string (the coordinates X and Y of the upper left corner of the character string whose origin is the upper left corner of the display area when the LCD 202 is placed horizontally). Further, in layer # 0 shown in FIG. 2, data (for example, character code) indicating each character (that is, each character of character number 0 to character number 4) constituting the character string in the general-purpose table 103 is stored. Font type attribute indicating the address (FCSA and FCEA) that defines the area, the type of font used to display each character, and the size of the character (number of pixels SZX in the horizontal scanning direction and number of pixels SZY in the vertical scanning direction) And the address (FTYP) of the area in which is stored.

  As shown in FIG. 2, the ROM 203 stores compressed font image data in the order of character codes for various characters for each font type such as Gothic and Mincho. In the present embodiment, the drawing processing for each character constituting the character string is realized by reading out and decoding the image data in the compression format of the font type indicated by the font type attribute in the order of the character number.

  As described above, in the present embodiment, since the LCD 202 is vertically arranged, all character strings displayed on the LCD 202 are vertical character strings. In this embodiment, three types of parameters such as a processing character number, a processing line number, and a display / non-display determination flag are associated with the character string in the register 104 in order to enable display of the vertical character string. Stored. Specifically, in the present embodiment, data (for example, layer # 0 in FIG. 2) that defines the display mode of the entire character string includes the addresses of the storage destinations of the three new parameters. Of course, the above three types of new parameters may be included in the data defining the display mode of the entire character string. The role of these three new parameters will be clarified in the operation example in order to avoid duplication. In this embodiment, in order to facilitate the display of the vertical character string, a compressed font of the vertical character string font (that is, a character font arranged so that the height direction coincides with the horizontal scanning direction). Data is stored in the ROM 203, and in the vertical character string attribute data, a value indicating the vertical character string font is set as the font type attribute.

  The controller 105 generates image data of various image constituent elements (that is, sprites, character strings, and lines) prior to display on the LCD 202 of the image data to be displayed in each vertical scanning period. This is a circuit for sequentially instructing 108. Specifically, the controller 105 creates an execution schedule of processing for generating image data of each image component based on the attribute data of each image component stored in the general-purpose table 103 in each vertical scanning period, In accordance with this execution schedule, an image data generation instruction for various image components is supplied to the image data generation unit 108. In the present embodiment, in addition to the introduction of the three types of new parameters described above, the controller 105 is caused to execute processing that significantly shows the features of the present embodiment, thereby realizing display of the vertical character string. This point will be described in detail later.

  The image data generation unit 108 is a circuit that executes processing for generating image data of various image components one line at a time in order from the first line and writing them to the line buffer of the image output unit 109 in accordance with an image data generation instruction from the controller 105 It is. As shown in FIG. 1, the image data generation unit 108 is connected to the ROM 203 via the decoding unit 107 and the ROM interface 106. The ROM interface 106 reads compressed image data (sprite data that is sprite image data or font data that is font image data) from the ROM 203 in accordance with an instruction given from the decoding unit 107, and outputs it to the decoding unit 107. To do.

  The decoding unit 107 reads compressed sprite data or compressed font data from the ROM 203 via the ROM interface 106 under the control of the controller 105, and decodes the image for one line instructed by the controller 105 in pixel units. And the decoding result is given to the image data generation unit 108. As shown in FIG. 1, the decoding unit 107 includes a pattern decoder 107A for decoding compressed sprite data and a font decoder 107B for decoding compressed font data. Although not shown in detail in FIG. 1, each of the pattern decoder 107A and the font decoder 107B has a first work memory for storing compressed data read from the ROM 203, and a predetermined number necessary for decoding subsequent pixels. And a second work memory for holding the pixel data of the compressed data stored in the first work memory while sequentially updating the storage contents of the second work memory. Decode with.

  The image data generation unit 108 includes a sprite rendering unit 108A, a font rendering unit 108B, and a line rendering unit 108C. The sprite rendering unit 108A is a circuit that performs editing (enlargement / reduction / deformation, color calculation, etc.) instructed by the image data generation instruction on the sprite data decoded by the decoding unit 107, and writes it to the line buffer. . The font rendering unit 108B is a circuit that performs editing (enlargement / reduction / deformation, color calculation, etc.) instructed by the image data generation instruction on the font data decoded by the decoding unit 107, and writes it to the line buffer. The line rendering unit 108C is a circuit that writes image data representing a line to the line buffer in accordance with an image data generation instruction.

The image output unit 109 includes line buffers 109A and 109B each having a capacity capable of storing image data for one horizontal scan line. Of these line buffers 109A and 109B, one is a write line buffer and the other is a read line buffer. The line buffer for reading is the one that has been the write line buffer up to that time in synchronization with the horizontal synchronizing signal of the LCD 202. A line buffer is used as a write line buffer. In each horizontal scanning period, one line of image data stored in the readout line buffer is read and supplied to the LCD 202 for display, while one line of image data displayed after one horizontal scanning period is displayed. The image data generation unit 108 writes the data in the writing buffer.
The above is the configuration of the image display LSI 100.

(B: Operation)
Next, the operation of the image display LSI 100 will be described.
As described above, in the general-purpose table 103 of the image display LSI 100, attribute data about sprites, character strings, and the like constituting an image displayed on the LCD 202 in each vertical scanning period is written by the host CPU 201 every vertical scanning period. . In each vertical scanning period, the controller 105 determines, for each horizontal scanning period, whether or not the horizontal scanning line in the next horizontal scanning period straddles each image component corresponding to the attribute data (that is, the next horizontal scanning). Whether to be a display target in a period) is determined, and an image data generation instruction for an image component determined to be a display target is generated for each image component and given to the image data generation unit 108.

If the determination target of whether or not to display in the next horizontal scanning period is a horizontal character string (see FIG. 4A), the display position Y in the vertical scanning direction indicated by the attribute data of the horizontal character string If the size SZY of the horizontal character string in the vertical scanning direction and the position VD of the horizontal scan line drawn in the next horizontal scanning period satisfy the relationship of the following expression (1), the controller 105 A character string is determined as a display target (the same applies when determining whether a sprite is a display target).
Y ≦ VD ≦ Y + SZY (1)

  On the other hand, in the case of a vertical character string (see FIG. 4B), it is possible to determine whether or not the first character is a display target using the above formula (1). For the characters after the character, it is not possible to determine whether or not they are display targets using the above formula (1). This is because data indicating the display position of each of the second and subsequent characters is attribute data in order to determine whether the second and subsequent characters of the vertical character string are to be displayed / hidden by the above formula (1). This is because such data is not included in the character string attribute data. Also, the vertical scanning direction display position of the character to be determined is added to the vertical scanning direction display position of the entire vertical character string by adding the size of all characters preceding the determination target character in the vertical scanning direction. Although it is not impossible to calculate the display position, the calculation of the display position for each character after the second character causes problems such as a decrease in drawing performance and an increase in the scale of the arithmetic circuit. .

  Therefore, in this embodiment, as described above, by introducing three new parameters of the processing character number, the processing line number, and the display / non-display determination flag, the drawing performance is reduced and the scale of the arithmetic circuit is increased. It is possible to display a vertical character string on a line buffer image processing apparatus without causing a problem. Here, the display / non-display determination flag indicates whether or not the horizontal scan line in the next horizontal scanning period straddles the vertical character string corresponding to the display / non-display determination flag (that is, the vertical character string). Is a parameter indicating whether or not to be a display target in the next horizontal scanning period). The processing character number is a parameter indicating a character straddling the horizontal scan line when the horizontal scan line straddles the vertical character string corresponding to the processing character number in the next horizontal scanning period. The processing line number is a parameter indicating how many lines of the character indicated by the processing character number overlap the horizontal scan line. Hereinafter, display control of the vertical character string using these three types of parameters will be described.

  In the present embodiment, the above three types of parameters are all reset to 0 when the image processing LSI 100 is initialized. Note that when writing attribute data for a character string, the host CPU 201 or the controller 105 may set 0 as an initial value to the above three types of parameters.

  First, the controller 105 performs the calculation shown in the above equation (1) as in the case of the horizontal character string to determine whether to display / hide the first character of the vertical character string. That is, the controller 105 determines that no display is performed until the position VD of the horizontal scan line to be drawn in the next horizontal scanning period reaches the display position Y included in the layer # 0 of the attribute data of the vertical direction character string. The three types of parameters are not updated. When the position VD of the horizontal scan line to be drawn in the next horizontal scanning period reaches the display position Y included in the layer # 0 of the attribute data of the vertical character string (that is, when VD = Y), the controller 105 starts updating the three types of parameters.

  More specifically, when the position VD of the horizontal scan line reaches the display position Y included in the layer # 0 of the vertical character string attribute data, the controller 105 sets the display / non-display determination flag to 1 (that is, Each time the horizontal scan line is updated (that is, the position VD of the horizontal scan line is incremented by 1) until the display / non-display determination flag is reset to 0. Every time, the following first and second processes are executed. The first process refers to the processing character number and processing line number at that time, and instructs the image data generation unit 108 to draw a line indicated by the processing line number of the character indicated by the processing character number. is there. In the second process, when the processing line number indicates the last line of the character (specifically, when the processing line number = character size SZX-1), the processing character number is incremented and the subsequent character is The processing line number is updated to a value indicating the first line of the subsequent character (that is, 0) while the processing line number does not indicate the last line. Is a process of incrementing and updating to a value indicating the next line. Thereafter, the controller 105 resets the display / non-display flag to 0 when the processing line number of the last character becomes a value indicating the last line.

  For example, for the vertical character string shown in FIG. 4B, when (7, 7) is set as the display position (X, Y) and SZX = SZY = 32 is set as the character size, In the process of updating the horizontal scan line position VD to 0, 1, 2,..., The three types of parameters are updated as shown in FIG. As shown in FIG. 3, during VD = 7 to 166, the display / non-display determination flag for the vertical character string is set to 1, and the drawing process for the vertical character string is performed. Specifically, since the processing character number = 0 during the period of VD = 7 to 38, drawing processing is performed for the first character (that is, “A”) of the vertical character string, and VD = 38. In this case, since the processing line number is “31” indicating the last line of the character, the processing character number is incremented to “1” and the processing line number is set to “0” when the horizontal scan line is updated. Similarly, since the processing character number = 1 in the period of VD = 39 to 70, the drawing process for the second character (ie, “B”) of the vertical character string is performed, and so on. Since the processing character number = 4 during the period of VD = 135 to 166, the drawing process is performed for the fifth character (that is, “E”) of the vertical character string. Then, as a result of performing the display process described above subsequent to the drawing process, the vertical character string “ABCDE” is displayed on the LCD 202.

  As described above, according to the present embodiment, it is possible to determine whether or not the current processing line is a display target without adding the vertical sizes of all the characters preceding the determination target character. Therefore, it is possible to display a vertical character string on an image processing apparatus that draws image data and displays it on a display using a line buffer having a storage capacity for one line.

(C: deformation)
Although one embodiment of the present invention has been described above, it goes without saying that the following modifications may be added to this embodiment.
(1) In the above embodiment, the vertical character string font data is stored in advance in the ROM 203 in addition to the horizontal character string font data, and the vertical character string font is displayed when the vertical character string is displayed. Data was used. However, the ROM 203 stores only the horizontal character string font data, and is used by rotating the font represented by the horizontal character string font data by 90 degrees clockwise when displaying the vertical character string. You may do it. The ROM 203 stores only the vertical character string font data. When displaying the horizontal character string, the font represented by the vertical character string font data is rotated 90 degrees counterclockwise. It may be used.

(2) In the above embodiment, a method of referring to the decoding result of several preceding pixels is adopted as a compression encoding method of sprite data and font data stored in the ROM 203, but other methods are adopted. Of course, sprite data and font data not subjected to compression encoding in the ROM 203 may be mixed with those subjected to compression encoding. Needless to say, when the ROM 203 stores only uncompressed sprite data and font data, the decoding unit 107 may be omitted.

(3) In the above-described embodiment, the application example of the present invention to the in-vehicle image display system has been described. For example, the image display system incorporated in so-called information home appliances such as a refrigerator, a washing machine, and a rice cooker having a display. Of course, the present invention may be applied. Even in this type of information home appliances, the space for installing the image display system and the installation space for the display cannot be sufficiently taken, and it is often necessary to install the display vertically or use a line buffer system. In addition, the display frequency of the character information is considered to be extremely high. For the same reason, it is conceivable to apply the present invention to an image display system of a portable information terminal such as a mobile phone, a portable game machine, or a PDA.

DESCRIPTION OF SYMBOLS 100 ... Image display LSI, 101 ... CPU interface, 102 ... Color palette memory | storage part, 103 ... General-purpose table, 104 ... Register, 105 ... Controller, 106 ... ROM interface, 107 ... Decoding part, 107A ... Pattern decoder, 107B ... Font decoder , 108: Image data generation unit, 108A ... Sprite rendering unit, 108B ... Font rendering unit, 108C ... Line rendering unit, 109A, 109B ... Line buffer, 109 ... Image output unit, 110 ... Clock generation unit, 201 ... Host CPU, 202 ... LCD, 203 ... ROM.

Claims (3)

A line buffer for storing image data representing an image for one scan line on the display;
A general-purpose table storing attribute data indicating a display mode of a character string to be displayed on the display;
A memory interface that reads font data of characters instructed to be read from a memory that stores font data representing fonts of various characters;
An image data generation unit that generates image data for one scan line using the font data read from the memory, and executes a drawing process to be written to the line buffer;
A controller that specifies characters across horizontal scan lines in each horizontal scanning period with reference to the attribute data stored in the general-purpose table, and instructs the image data generation unit to perform drawing processing on the corresponding characters; Equipped,
The character string is a vertical character string in which the height direction of each character constituting the character string matches the horizontal scanning direction, and the characters are arranged in the vertical scanning direction,
The controller updates the parameter indicating the character across the horizontal scan line and the number of lines of the character across the horizontal scan line when the horizontal scan line extends across the vertical character string. An image processing apparatus that instructs the image data generation unit to execute a drawing process on a line indicated by the parameter of the character indicated by the parameter.   The memory stores vertical character string font data representing a font in which the height direction of characters is matched with the horizontal scanning direction. In the vertical character string attribute data, the vertical direction is used to draw the constituent characters. The image processing apparatus according to claim 1, wherein use of character string font data is designated. The font data stored in the memory is subjected to compression encoding,
The image processing apparatus according to claim 1, further comprising a decoding unit that decodes the font data read from the memory and supplies the decoded font data to the image data generation unit.

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