JP5057895B2 - Image output apparatus and screen composition method - Google Patents

Description

  The present invention relates to an image output apparatus and a screen configuration method for rendering bitmap data on a background image at high speed on an on-screen display (hereinafter referred to as OSD).

  Conventionally, the method of drawing bitmap data in a frame memory is generally performed at a high speed using hardware. The use of hardware acceleration provides the effect of speeding up the drawing of bitmap data, but drawing that requires computational processing with a high CPU load that does not provide the effect of hardware acceleration is sufficiently fast. Could not do.

  One of the processes that require time for drawing processing is alpha blend processing. The alpha blending process is a process of superimposing a translucent image on another image, and translucently synthesizes two images using a coefficient called an alpha value. A device with high multiplication / division processing capacity, such as a personal computer, can perform alpha blending at a sufficiently high speed, but a device with low processing capacity compared to a personal computer must perform alpha blending at high speed. Is difficult.

  To enable alpha blend processing without fraud even in a device with low CPU capacity and no large-capacity memory, if alpha blend processing is not possible in the frame memory, alpha is generated when intermediate data is generated. In a printing device that has a process that preprocesses the blending process and puts the intermediate data in a state that does not include the alpha blending process, the intermediate data has a table that describes the data used for drawing and alpha blending information when generating the intermediate data There has been proposed an image processing apparatus that has generation means for generation and has means for efficiently performing removal processing by performing processing for removing alpha blend processing from intermediate data based on a table describing alpha blend information. (See Patent Document 1).

JP 2006-244248 A

  However, since the technology for removing the alpha blending process in the conventional printing apparatus requires pre-processing, the same technique cannot be applied when displaying the OSD in a digital broadcast recorder that requires immediate drawing responsiveness. .

  An object of the present invention is to perform OSD drawing that requires immediate response, such as focus movement display on a menu screen of a recorder, at high speed.

The image output apparatus of the present invention includes:
In a device that displays a single screen by overlapping rectangular screen components of multiple still images,
When replacing a first screen component constituting one screen with a second screen component, the area of the second screen component is exactly the same as the area occupied by the first screen component, or the first Condition determining means for determining whether or not the entire area occupied by one screen component is included;
Synthesis processing means for performing screen synthesis by superimposing foreground pixels and background pixels,
When the area of the second screen component is exactly the same as the area occupied by the first screen component or includes the entire area occupied by the first screen component, Rendering the second screen part without erasing the first screen part from the frame memory ;
The condition determining means determines whether it is necessary to process screen composition at high speed,
When image composition needs to be processed at high speed, screen composition processing that performs arithmetic processing involving multiplication and division is prohibited .

  According to the present invention, since it is not necessary to perform a clear process before newly drawing, it is possible to draw on the OSD at high speed.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an image output apparatus according to Embodiment 1 of the present invention. The illustrated image output apparatus displays a single screen by superimposing a plurality of still image screen components. The image classification management means 1, the condition determination means 2, the clear processing means 3, the composition processing means 5, the video decode Means 6 and drawing means 7 are provided.

The image classification management unit 1 classifies the bitmap images constituting the screen parts in accordance with the composition processing method, and manages the method of using the still image screen part display command.
The image classification management unit 1 classifies, for example, a still image screen component including a pixel that is totally transmissive and a still image screen component that is drawn at a transmittance other than total transmissive by combining processing, and displays a still image screen. Manage how to use the display command for parts. Each screen component occupies a rectangular area on the screen, and the coordinates of the four vertices are represented by (xa, ya), (xa, yb), (xb, ya), (xb, yb). Is done. Here, xa and xb are coordinate values in the horizontal direction (horizontal direction) on the screen, and ya and yb are coordinate values in the vertical direction (vertical direction) on the screen.

The condition determination means 2 determines whether the area occupied by the currently drawn screen component has a portion that protrudes from the area occupied by the screen component to be drawn.
2A to 2D, the symbol Pa represents the area occupied by the currently drawn screen component, and the symbol Pb represents the region occupied by the screen component to be drawn.
The region Pa and the region Pb shown in FIG. 2 (a) partially overlap each other, the region Pa has a portion protruding from the region Pb, and the region Pb has a portion protruding from the region Pa. .
The region Pa shown in FIG. 2B does not have a portion that protrudes from the region Pb, and the region Pb has a portion that protrudes from the region Pa. The area Pa shown in FIG. 2A and the area Pa shown in FIG. 2B are in the same position and have the same size, and the area Pb shown in FIG. This is the smallest rectangular area including both the whole area Pa shown in a) and the whole area Pb shown in FIG. 2A (indicated by reference numeral Pb ′ in FIG. 2B). .
The region Pa shown in FIG. 2C does not have a portion that protrudes from the region Pb, and the region Pb has a portion that protrudes from the region Pa.
Area Pa as shown in FIG. 2 (d) has a portion protruding to the region Pb, region Pb is not to have a portion protruding to the region Pa.
Although not shown, when the region Pa and the region Pb are the same, neither region has a portion that protrudes from the other region.

  The condition determining means 2 determines whether the area occupied by the currently drawn screen component has a portion that protrudes from the area occupied by the screen component to be drawn, and determines whether the screen component to be drawn is Whether alpha blending is required, color key processing is required, or neither of these is performed and only normal data transfer processing (complete overwrite processing) is performed Do.

  The clear unit 3 executes a process of clearing the currently drawn screen component area when it is determined by the condition determination of the condition determination unit 2 that it is necessary to clear the currently drawn screen component. When this clear process is performed, the value of each storage position in the frame memory in the drawing means 7 is replaced with an initial value, for example, a value representing white.

  The composition processing means 5 can selectively perform a translucent process such as an alpha blend process, a color key process, and a normal transfer process (complete overwrite process).

  For example, as shown in FIG. 3, the composition processing unit 5 includes a first layer graphics generation unit 41, a first first layer switch 42, a first layer alpha blend processing unit 43, a first layer color key processing unit 44, Second first layer switch 45, first layer graphics memory 46, second layer graphics generation means 51, first second layer switch 52, second layer alpha blend processing means 53, second layer color key processing Means 54, a second second layer switch 55, a second layer graphics memory 56, and an adding means 61.

  When the condition determining means 2 determines that the alpha blending process is necessary, the bitmap data of the screen parts generated by the first layer graphics generating means 41, 51 is converted to the alpha blend processing means 43 by the switches 42, 52. , 53 and subjected to alpha blending processing, and then supplied to the adding means 61 via the switches 45, 55.

  When the condition determining means 2 determines that the color key processing is necessary, the bitmap data of the screen parts generated by the first layer graphics generating means 41 and 51 is converted to the color key processing means 44 by the switches 42 and 52. , 54, undergoes color key processing, and then supplied to the adding means 61 via the switches 45, 55.

  When the condition determining unit 2 determines that the normal process (complete overwrite process) should be performed without receiving either the alpha blend process or the color key process, the first layer graphics generating unit 41, 51 generates The bitmap data of the screen component is supplied to the adding means 61 via the switches 42 and 52 and the switches 45 and 55 (without passing through the alpha blend processing means 43 and 53 and the color key processing means 44 and 54). Is done.

  The adding means 61 adds the input data (for each pixel) and outputs the result. The data output from the adding means 61 is written into the frame memory 8 in the drawing means 7. The drawing means 7 displays the data stored in the frame memory 8 on the OSD.

  As a method of classifying images in the image classification management means 1, when input image data constituting a screen component is bitmap data in PNG format, a transparent process is performed by checking whether an alpha channel exists in the data structure. Can be determined. Further, a program for checking the PNG data structure may be created by software to automatically perform image classification. Furthermore, the person who designs the screen may perform the image classification independently, ignoring the presence or absence of the alpha channel.

  FIG. 4 shows an example of the data structure of each screen component handled by the image classification management means 1. It holds file name, blend type, size, area name, and position information (x coordinate, y coordinate). The x-coordinate and the y-coordinate represent the horizontal position and the vertical position of the top left corner of each screen component, for example.

  The classification of the bitmap data with respect to the blend type is classified based on whether it is configured without total transmission or non-transmission, or is a bitmap designating an intermediate transmittance. Those using an intermediate transmittance are classified as those requiring alpha blend processing by the alpha blend processing means 43 and 53.

  Those that are totally transparent are classified as those that are subjected to processing by the color key processing means 44 and 54, and an arbitrary color that is not used in the image is painted on the transparent portion, and the color is set as a color key.

As another example of the image classification management means 1, the necessity of the synthesis processing with the bitmap data before running the program for checking the above PNG data structure by adding a prefix to the file name of the bitmap data. May be distinguished.
For example, “ab_” is added to a file name that requires alpha blending processing, as illustrated in the second row of the table of FIG. As shown in the third row of the table of FIG. 4, “ck_” is added to a file that needs color key processing. As illustrated in the fourth row of the table in FIG. 4, “no_” is added to the normal processing file. In this way, the condition judging means 2 can simplify the software because it is not necessary to analyze the contents of the bitmap data.

  In the condition determination means 2, the area (drawing area) Pa (FIGS. 2A to 2D) occupied by the currently drawn screen component for the image for which drawing has been instructed, and the screen component to be drawn from now on occupy. The region (drawing region) Pb (FIGS. 2A to 2D) is compared to determine whether the drawing region Pa has a portion that protrudes from the drawing region Pb. When there is no protruding part (in the case of FIGS. 2B and 2C), the clear process is not executed, the blend type is determined, and the blend process is performed according to the determination result. .

  If the area Pa has a portion protruding from the area Pb (in the case of FIG. 2A and FIG. 2D), the clear processing means 6 executes the clear process.

  In this case, by configuring the screen component to be drawn so as to occupy an area larger than the area originally necessary for that purpose, the clear process can be eliminated or reduced. For example, if the area originally required for the configuration of the screen part is indicated by the symbol Pb in FIG. 2A, it is not the screen part occupying the area Pb shown in FIG. By configuring and using the screen parts occupying the area Pb shown, that is, the whole area Pa and the screen parts occupying a rectangular area including the whole area Pb in FIG. Alternatively, it can be reduced.

  For example, when a button image is displayed as a screen component, the vertical and horizontal dimensions of the button image, the positions to be arranged, and the number of images are replaced with other images in order to reduce the calling frequency (execution frequency) of the clear process. It is also possible not to change the case.

  By doing this, each time the next bitmap image (as a screen component) is drawn to replace the current bitmap image (as a screen component) with the next (as a screen component) bitmap image This eliminates the need to execute the clearing process before performing the bitmap display, and the bitmap image switching display becomes faster. That is, the clear process is executed only when the entire OSD display is erased, and the number of times (frequency) of the clear process can be reduced.

FIG. 5 shows a processing procedure in the condition determining means 2.
First, the area occupied by the bitmap image (new image) as the screen part to be drawn is compared with the area occupied by the bitmap image (current image) as the currently drawn (displayed) screen part. If the area occupied by the current image has a portion that protrudes from the area occupied by the new image (FIGS. 2A and 2D) (Yes in step S71), the current drawing is started before starting a new drawing. A process (clear process) for erasing the bitmap image being performed is performed (step S74).

  When the area occupied by the current image does not have a portion protruding from the area occupied by the new image, that is, when the area occupied by the new image is the same as the area occupied by the current image or has a portion protruding (FIG. 2B ), (C)) (No in step S71), the process proceeds to step S72 for the image composition process without executing the clear process.

First, the following determination is made based on the classification result of the composition processing method by the image classification management means 1.
In step S72, it is determined whether or not the bitmap image (new image) as the screen component to be drawn requires transparency processing (S72). When the transmission process is not necessary (No in step S72), the process proceeds to step S75, and the normal process (complete overwrite process) for transferring the image data as it is without performing the image synthesis process is performed.
If any transmission processing is necessary (Yes in step S72), the process proceeds to step S73, where it is determined whether full transmission or semi-transmission is necessary.

If full transmission is required, that is, bitmap data including only a part that is not translucent but full transmission (Yes in step S73), the process proceeds to color key processing in step S76. This color key processing will be described later.
In the case of No in step S73, since it is necessary to perform the semi-transparent process, the process proceeds to the alpha blend process in step S77.

  Alpha blend processing can also be performed on bitmap images that do not require transparency processing, but by adding the condition determination means 2 in FIG. 1, it is divided into those that can be processed at high speed and those that take time to process. Since it is possible to perform alpha blending on those that can be performed and to perform alternative processing on those that cannot be processed at high speed, it is possible to reduce the time required for drawing as a whole.

The alpha blending processing performed by the alpha blending processing means 43 and 53 includes a method in which the entire image is made semi-transparent using one common alpha value, or a pixel-by-pixel using an alpha value for each pixel of the image. There is a way to synthesize. When the alpha value takes an integer value in the range of 0 to 255, the formula for the alpha blend process for each of the r, g, and b components is expressed as follows.
r = {rf · a + rb · (255−a)} / 255 (1R)
g = {gf · a + gb · (255−a)} / 255 (1G)
b = {bf · a + bb · (255−a)} / 255 (1B)
In the above formulas (1R), (1G), and (1B), rf is the first layer, for example, the foreground red component, rb is the second layer, for example, the background red component, gf is the foreground green component, and gb is The green component of the background, bf is the blue component of the foreground, bb is the blue component of the background, and a is the α value of the foreground. By rewriting equation (1R) as follows, multiplication and division can be reduced from three to two.
r = rb + (rf−rb) · a / 255 (2R)
Equations (1G) and (1B) can be similarly modified.

  The first layer alpha blend processing unit 43 multiplies the foreground bitmap image supplied from the first layer graphics generation unit 41 and the alpha value (α = a / 255), performs translucent processing, and performs the first layer graphic. Data is transferred to the memory 46.

Similarly, the second layer alpha blend processing unit 53 multiplies the background bitmap image supplied from the second layer graphics generation unit 51 by the alpha value (1−α) = (255−a) / 255) half. Transparency processing is performed and transferred to the second layer graphic memory 56.
The adding means 61 performs synthesis by adding the data read from the first layer graphics memory 46 and the data read from the second layer graphics memory 56. The synthesis result output from the adding unit 61 is transferred to the drawing unit 7 as an output of the synthesis processing unit 5.

The video decoding means 6 decodes the moving image and transfers it to the drawing means 7.
The drawing unit 7 combines the output of the synthesis processing unit 5 and the output of the video decoding unit 6 to obtain an image obtained by superimposing the moving image and the bitmap still image.

  The lower layer image can be seen at the place designated as transparent or semi-transparent. When the alpha coefficient is expressed in the range of 0/255 to 255/255, the lower layer image is overwritten with the upper layer image, so that the lower layer image is overwritten with the upper layer image. Is invisible to the user.

The bitmap data classified as requiring the color key processing by the condition determining means 2 is at least partly painted with the color key by the color key processing means 44, 54, and the portion (pixel) painted with the color key. Only the bitmap data other than () is transferred to the graphics memories 46 and 56, and further transferred to the frame memory 8 in the drawing means 7 via the adding means 61.
The portion painted with the color key is not transferred to the frame memory 8.
As a result, the background image is displayed as it is in the portion painted with the color key (displayed as being seen through). Since this processing does not require multiplication or division calculation processing unlike the alpha blend processing, drawing with the color key is performed at a higher speed than the alpha blend processing.

  When the bitmap image is rendered in the first layer graphic generation unit 41, the bitmap image is sent to the first layer color key processing unit 44. If pixels other than the color designated as the color key are included in the bitmap, the color is displayed. In the key processing means 44, the pixels other than the color key are transferred to the first layer graphic memory 46. The color key portion is not written in the graphic memory 46.

  The operations of the second layer graphics generation unit 51, the second layer color key processing unit 53, and the second layer graphics memory 56 are the same as described above.

For an image as a screen component that does not require transparency processing, the outputs of the first layer graphics generation unit 41 and the second layer graphics generation unit 51 are directly sent to the first layer graphics memory via the switches 42, 45, 52, and 55. 46, transferred to the second-layer graphics memory 56, and then transferred to the frame memory 8 via the adding means 61.
Also in this case, as in the color key process, the alpha blending calculation process does not occur, so that drawing is performed at a high speed.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing an image output apparatus according to Embodiment 2 of the present invention. In FIG. 6, the same reference numerals as those in FIG. 1 denote the same or similar members.
A personal computer 31 applies a staggered color key pattern shown in FIGS. 7A and 7B to the bitmap data BMD as a screen component. That is, pixels that overlap the color key patterns in FIGS. 7A and 7B are replaced with pixels of the color of the color key, and a replaced bitmap image is generated. The size of the portion to be replaced with the color key (and hence the area ratio relative to the whole) can be changed according to the transmittance. When images with different transmittances (for example, n types of images) are required, images with different sizes (n types) to be replaced with color keys are prepared. FIG. 7A shows a case where the size of the portion replaced with the color key is relatively small, and FIG. 7B shows a case where the size of the portion replaced with the color key is relatively large. The data of the generated image (image with the color key pattern overcoated) is written to a recording medium 32 such as a flash memory or a memory card together with a program for operating the image output device and provided to the image output device. Is done.

  By using an image overcoated with such a color key pattern, a pseudo alpha blend image (“pseudo translucent image”) can be generated by performing color key means processing instead of performing alpha blend processing. it can.

Embodiment 3 FIG.
FIG. 8 is an example of the OSD screen layout. 11 is a display screen, 12 is a button image that is in focus (highlight), 13 and 14 are button images that are not in focus, and 15 is a display content that changes depending on the button that is in focus. This is an information display area.

  When the screen indicated by reference numeral 11 is displayed, the focus moves from the button 12 to the button 13 by pressing the up and down cursor keys on the remote control. In order to perform such display, there is a method of preparing two types of images, one focused image and one unfocused image, for each button. At that time, if you set the focused and the same width and height as the unfocused one, you only need to overwrite it when you redraw the button image, and you need to call the clear process. Absent. In this way, the button images displayed at the fixed positions are all the same size, and the clear process is called only when the entire OSD is not displayed.

Embodiment 4 FIG.
FIG. 9 shows an OSD when a moving image is used as a background. In the figure, 21 is a display screen, 22 is a background video, and 23 is a time code expressed in OSD. For OSD drawing that requires a real-time response that requires immediate responsiveness, such as time code, the display is updated, and drawing is performed by color key processing. In FIG. 9, when one bitmap image is pasted for each character, a number is written in a rectangle. Therefore, if no composition processing is performed, a lower-layer video or still image around the number is displayed. Is hidden. In order to solve this problem, the background of the number is filled with the color key, and the color setting of the color key is performed. Since the part painted with the color key is not transferred to the graphic memory, a number is displayed on the synthesized screen without a rectangular background.

Embodiment 5 FIG.
When configuring a screen that does not place importance on the drawing speed that does not require real-time performance, there is no problem even if the alpha blending process is performed. When focus movement is performed in conjunction with the remote control operation as in the third mode, the display speed may not be able to catch up if an image for alpha blending is used.

  In order to solve this problem, as shown in FIG. 10, a screen mode management means 2c for determining whether to perform high-speed display is added in the condition judgment means 2. In a scene that requires an immediate response such as a screen design for switching the focus display of a button image or a clock display, screen composition processing that performs arithmetic processing involving multiplication and division, such as alpha blending processing, is prohibited.

  On the other hand, alpha blend processing is permitted when the immediate responsiveness is not so required, for example, when the detailed program information is displayed on a screen whose background is a moving image.

  FIG. 11 shows a processing flow. FIG. 11 is a modification of the processing flow of FIG. 5, and the same reference numerals as those in FIG. 5 indicate similar processing steps.

  If it is not total transmission in step S73 (No in step S73), the process proceeds to step S91. In step S91, it is determined whether or not the mode requires real-time characteristics (that is, a mode for performing high-speed display). If real-time characteristics are not required (No in step S91), the process proceeds to step S77 and alpha blending processing is performed. Do.

  When real-time characteristics are required (Yes in step S91), an alternative image that can perform color key processing using an image that shows through the background without using alpha blending as described in the second embodiment (Satoshi Chidori) The image is replaced with an image coated with a child color key pattern, that is, a pseudo-translucent image (step S92), and the process proceeds to step S76 to perform color key processing.

  Note that mode management for the necessity of real-time capability can be realized by turning on and off (ON, OFF) a flag of a program for drawing.

  Display suitable for processing in the alpha blend prohibition mode includes movement display of focus (highlight) by operating the cursor key of the remote controller shown in FIG. 8, sports program time display, subtitle display, and the like. . Display suitable for processing in the alpha blend permission mode includes channel number display, program name display, and program detailed information display.

Embodiment 6 FIG.
FIG. 12 shows an image output apparatus according to the sixth embodiment. The illustrated image output apparatus is generally the same as that shown in FIG. 10, but the condition determination means 2 includes an area management means 2d.

  FIG. 13 is a diagram for explaining the operation of the sixth embodiment. In FIG. 13, reference numeral 81 denotes the entire screen, and reference numeral 82 denotes a main area of the moving image, which indicates an area (also referred to as “alpha blend essential area”) that is desired to prevent the display of the moving image by the OSD. Reference numeral 83 denotes an area where the user does not care much even if a part of the moving image is hidden. In the illustrated example, the region 83 is located in the peripheral portion of the screen, and the region 82 includes a central portion of the screen, that is, a portion other than the peripheral portion 83. When displaying the OSD so as not to disturb the display of moving images as much as possible, in addition to the mode management means 2c shown in the fifth embodiment, means 2d for area management is included in the condition judgment means 2 as shown in FIG. The main area 82 of the moving image is an area in which the alpha blending process is indispensable, and the area 83 that the user does not care much even if a part of the moving image is hidden is processed as an area that does not need the alpha blending process. When drawing in an area 83 that does not require alpha blending processing, color key processing using an image painted with the color key pattern of FIG. 7 is performed.

  FIG. 14 shows the operation of the apparatus of the sixth embodiment. FIG. 14 is generally the same as FIG. 11 except that step S93 is added.

  If real-time performance (high-speed processing) is not required, No is determined in step S91 in FIG. 14, but then region determination is performed in step S93. In this area determination, it is determined whether or not the position where the bitmap to be drawn is arranged overlaps the alpha blend essential area 82 in FIG. If a bitmap is to be rendered in the alpha blend required area 82, the alpha blend process in step S77 is executed. If a bitmap image is to be rendered only in the alpha blend unnecessary area 83, the process proceeds to step S92, where color Color key processing (S76) is performed using an image (substitute image) painted with a key pattern. By doing so, the arithmetic processing can be further reduced.

  Note that step S91 may be omitted, and the process may proceed to step S93 when No in step S73. In other words, the region determination may be performed without determining whether the mode is the real-time requirement mode, and the alpha blend process or the color key process using the substitute image may be performed according to the result.

  As an application example of the present invention, it can be applied to OSD display of a video recorder and a television receiver.

1 is a block diagram illustrating an image output device according to a first embodiment of the present invention. (A)-(d) is a figure which shows the relationship between the screen components currently drawn and the screen components which are going to draw from now on. It is a block diagram which shows an example of the synthetic | combination process means of FIG. 3 is a diagram illustrating a data structure of a screen component used in the image output apparatus according to Embodiment 1. FIG. It is a flowchart which shows the process sequence of the condition judgment means 2 of FIG. It is a block diagram which shows the image output device of Embodiment 2 of this invention. (A) And (b) is a figure which shows the example of the color key pattern used in Embodiment 2. FIG. It is a figure which shows the example of an OSD screen layout. It is an example of OSD when a moving image is used as a background. It is a block diagram which shows the image output device of Embodiment 5 of this invention. It is a flowchart which shows the process sequence of the condition judgment means 2 of FIG. It is a block diagram which shows the image output device of Embodiment 6 of this invention. It is a conceptual diagram of area management. It is a flowchart which shows the process sequence of the condition judgment means 2 of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image classification management means, 2 Condition judgment means, 3 Clear processing means, 5 Composition processing means, 6 Video decoding means, 7 Drawing means, 8 Frame memory, 41 1st layer graphic generation means, 42 Switch, 43 Alpha blend processing means 44 color key processing means, 45 switch, 46 first layer graphic memory, 51 second layer graphic generation means, 52 switch, 53 alpha blend processing means, 54 color key processing means, 55 switch, 56 second layer graphic memory, 61 Addition means.

Claims (4)

In a device that displays a single screen by overlapping rectangular screen components of multiple still images,
When replacing a first screen component constituting one screen with a second screen component, the area of the second screen component is exactly the same as the area occupied by the first screen component, or the first Condition determining means for determining whether or not the entire area occupied by one screen component is included;
Synthesis processing means for performing screen synthesis by superimposing foreground pixels and background pixels,
When the area of the second screen component is exactly the same as the area occupied by the first screen component or includes the entire area occupied by the first screen component, Rendering the second screen part without erasing the first screen part from the frame memory ;
The condition determining means determines whether it is necessary to process screen composition at high speed,
An image output device characterized by prohibiting screen composition processing for performing arithmetic processing involving multiplication and division when image composition needs to be processed at high speed . In a device that displays a single screen by overlapping rectangular screen components of multiple still images,
When replacing a first screen component constituting one screen with a second screen component, the area of the second screen component is exactly the same as the area occupied by the first screen component, or the first Condition determining means for determining whether or not the entire area occupied by one screen component is included;
Synthesis processing means for performing screen synthesis by superimposing foreground pixels and background pixels,
When the area of the second screen component is exactly the same as the area occupied by the first screen component or includes the entire area occupied by the first screen component, Rendering the second screen part without erasing the first screen part from the frame memory;
In addition to the screen image of the still image to be translucently processed, an image for pseudo translucent processing replaced with a color key pattern at an area ratio corresponding to the transmittance of the screen component is prepared,
The condition determining means determines whether or not the still image screen component should be processed at a high speed,
The composition processing means performs composition using the pseudo-translucent processing image when it should be processed at high speed, and performs semi-transparent processing when it should not be processed at high speed. the images output device you. In a method of displaying a single screen by superimposing rectangular screen components of multiple still images,
When replacing a first screen component constituting one screen with a second screen component, the area of the second screen component is exactly the same as the area occupied by the first screen component, or the first A condition determining step for determining whether or not the entire area occupied by one screen component is included;
A composition processing step for performing screen composition by superimposing foreground pixels and background pixels,
If the area of the second screen component is the same as the area occupied by the first screen component or includes the entire area occupied by the first screen component, Rendering the second screen part without erasing the first screen part from the frame memory ;
The condition determining step determines whether it is necessary to process the screen composition at a high speed. If it is necessary to process the image composition at a high speed, the screen composition process for performing arithmetic processing involving multiplication and division is prohibited. A screen composition method characterized by: In a method of displaying a single screen by superimposing rectangular screen components of multiple still images,
When replacing a first screen component constituting one screen with a second screen component, the area of the second screen component is exactly the same as the area occupied by the first screen component, or the first A condition determining step for determining whether or not the entire area occupied by one screen component is included;
A composition processing step for performing screen composition by superimposing foreground pixels and background pixels,
If the area of the second screen component is the same as the area occupied by the first screen component or includes the entire area occupied by the first screen component, Rendering the second screen part without erasing the first screen part from the frame memory;
In addition to the screen image of the still image to be translucently processed, an image for pseudo translucent processing replaced with a color key pattern at an area ratio corresponding to the transmittance of the screen component is prepared,
The condition determining step determines whether or not to process the still image screen component at a high speed,
The composition processing step performs composition using the pseudo-translucent processing image when it is to be processed at high speed, and performs semitransparent processing when it is not to be processed at high speed. to that screen configuring and.

Images