JPH0869539A - Method and equipment for decision of region extent of picture - Google Patents

Abstract

PURPOSE: To provide the device and method to decrease number of processes by deciding an area extent of an image generated from a plurality of image objects to conduct quick post-processing for expression of the image. CONSTITUTION: A display area 400 is divided into a plurality of areas and which of the areas are intersected with a plurality of image objects 410, 420 is decided. A marking is stored in a memory area corresponding to the display area decided to be intersected with at least either of the image objects.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to computer graphics systems, and more particularly to a method and apparatus for determining image area extents.

[0002]

2. Description of the Related Art In computer graphics systems, it is desirable to display two-dimensional or three-dimensional drawings on a two-dimensional display. Typically, such drawings are structures or images that can be stored in memory as a set of 2D or 3D objects. For example, an object has a set of vertices P (0),
Specified as P (1), ..., P (n-2), P (n-1). Here, n is the number of vertices of the object.
Each vertex P (i) normally has a position V in the coordinate space.
(I) and at least one function f (V (i)) such as a color factor. The color factor will later change the color (including grayscale) change (luminance,
It is a function evaluated at each vertex displayed as (such as temperature characteristics, humidity factors, etc.). This color factor is converted to each color and used to obtain a realistic or informative graphic image.

In representing an object, the object is fragmented into smaller objects, rasterized in a series of parallel spans, and a pixel representation of each span is calculated to determine the position or pixel address (usually X, Y
Are modified to have various functions such as (in space) and the color for that pixel, and so on.

Once rendered, various post-representational processes will be performed on the rendered image. For example, a clear command is used to change the value of each pixel in the rendered image to a single color and erase the image.
Further, the color comparison command is executed when a pixel having a particular color changes, for example to another color. As a result of the large number of pixels undergoing the post-representation process, the post-representation process is typically computer intensive.

One technique used to reduce the number of pixels that undergo the post-representation process is to perform the post-representation process only on those pixels that are in the region extent of the representation image. That is, the extent of the representation image is typically a rectangular box that intersects the minimum, maximum x, y values of the representation image. By processing only pixels within this region of the image, the number of pixels that need to undergo post-representation processing is significantly reduced.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for determining the area extent of an image created from multiple image objects to reduce post-rendering processing of the image. And

[0007]

In order to solve the above problems, an apparatus for determining an area extent of an image created from a plurality of image objects according to the present invention is a device for dividing a display area into a plurality of display areas. A device for determining which display area may intersect a plurality of image objects, and a device for storing an indicator in a memory for at least the display area determined to intersect with one of the image objects. In addition, the method of determining the area extent of an image created from a plurality of image objects according to the present invention includes a step of dividing the display area into a plurality of display areas and a display area that may intersect with the plurality of image objects. There is the step of determining if there is, and the step of storing the indicator in a memory for the display area determined to intersect at least one of the image objects.

[0008]

As described above, the present invention is directed to an apparatus and method for determining a region extent of an image created from a plurality of image objects to reduce post-rendering processing of the image. In the preferred embodiment of the present invention, the display area is divided into a plurality of regions. As each object in the image is rendered, it determines which region, or extent, it reaches the object, and flags that region to be modified during the rendering process. Once this is completed, that region flag will be used, leaving only those regions of the display that can be modified during the rendering process during the post-rendering processing step. This reduces the number of processes required after expression such as sharpness, color comparison adjustment, zooming, window movement, etc., and thereby speeds up post-expression processing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the basic configuration of a conventional digital computer 100 used in the preferred embodiment of the present invention. Computer 10
0 has one or a plurality of main processors 110, which are connected to a memory 120 and a hard disk 125 in a computer box 105, and an input device 130 and an output device 140 are attached to the computer box 105. Has been. Output processor 110 may be a single processor or multiple processors. Input device 130 may be a keyboard, mouse, tablet, or other type of input device. The output device 140 can also include a text monitor, plotter, or other type of output device.

A computer readable removable medium 190, such as a magnetic diskette or compact disc, is a disk drive or CD-ROM.
It can be inserted into an input / output device (hereinafter referred to as an I / O device) 180 such as a drive. Data is read or written from the removable media 190 by the I / O device under the control of the I / O device controller 170. This I / O device controller 170 is the bus 1
It is electrically connected to the main processor 110 via 60.
The main memory 120, the hard disk 125, the removable medium 190, etc. are used as a memory for storing data for processing by the main processor 110.

The main processor 110 can also be connected via a graphics adapter 200 to a graphics output device 150, such as a graphics display. The graphics adapter 200 sends image-related instructions from the main processor 110 to the bus 16
Receive through 0. The graphics adapter then executes the instructions on multiple or singular graphics adapter processors 220 connected to the graphics adapter memory 230. The processor 22
0 executes the instruction and updates the frame buffer 240 based on the instruction. The plurality of graphics processors 220 can be serial pipeline processors, a set of parallel processors, or a combination thereof, with each processor responsible for a portion of the task to be performed. Graphics processor 220 may also have specialized rendering hardware for rendering a particular type of primitive. The graphics memory 230 is processed by the processor 220 such as object data, intermediate operation data (such as stencil buffer or partially represented object data), and completed data to be loaded into the frame buffer 240. Used to store information. The frame buffer 240 contains data for each pixel to be displayed on the graphics output device. RAMDAC (read / write storage device digital
The analog converter 250 converts the digital data stored in the frame buffer 240 into RGB signals that are supplied to the graphics display 150, thereby representing the desired graphics output from the main processor 110.

FIG. 2 is a block diagram illustrating the layers of code typically used by a host computer and graphics adapter to perform graphics functions. An operating system 300, such as UNIX, provides the main control of this host computer. An operating system kernel 310 is attached to the operating system and provides hardware intensive tasks to the operating system. The operating system kernel connects directly to the host computer microcode 320. The host computer microcode 320 is the host
It is the main instruction set executed by a computer processor. Operating system 300 includes graphics applications 330 and 332
Is connected. This graphics application software is Silicon Graphic's GL, IBM's gr
It is possible to have software packages such as aPHIGS, MIT's PEX, etc. The graphics applications 330 and 332 are connected to graphics application APIs (application program interfaces) 340 and 342, respectively. APIs provide many computationally intensive tasks for graphics applications,
And graphics drivers such as device drivers for application software and graphics adapters.
Provides an interface with the hardware side. For example, APIs 340 and 342 are respectively GAI (graphics application interface) 35
0,352 can be connected. GAI is an application API and graphics adapter device driver 37
Provides an interface between 0s. In some graphics systems, this API also performs GAI functions.

Graphics application, AP
I, and GAI are considered by the operating system and device drivers as separate processes. That is, the graphics applications 330, 33
2, API 340, 342, and GAI 350, 35
2 is considered by operating system 300 and device driver 370 as processes 360, 362, respectively. The process is identified by the operating system and the device driver is identified by the process identifier (PID) assigned to the process by the operating system kernel. Process 360, 362
It is also possible to use the same code that is executed twice at the same time, each executing one program in two different windows. PIDs are used to distinguish different executions of the same code.

The device driver is a graphics kernel that is an extension of operating system kernel 310. This graphics core communicates directly with the microcode of graphics adapter 380. In many graphics systems, the GAI, or the API when the GAI layer is not used, can request access to the adapter microcode directly from the GAI or API by sending an initial request command to the device driver. . In addition, many graphics systems also allow the adapter microcode to access the GAI directly from the adapter microcode by sending an initial request command to the device driver, or when the GAI layer is not used. Both processes are hereafter referred to as direct memory access (DMA). DMA is typically used in transferring large blocks of data. By eliminating the need for the device driver to make a separate request through the display driver to set up the DMA, the DMA provides a fast data transfer between the host computer and the adapter. In some cases, it makes use of context switching, which allows adapter microcode to replace the current properties utilized by the adapter microcode. Context switching is used when the adapter microcode receives an instruction from a graphics application that utilizes a characteristic other than the adaptive microcode currently in use. Context switching is typically initiated by device drivers that allow the property to change.

Blocks 300-340 are software code layers that are typically independent of the type of graphics adapter utilized. Blocks 350-38
0 is a software code layer that typically depends on the type of graphics adapter utilized. For example, using different graphics adapters for graphics application software would require new GAI, graphics kernel, and adapter microcode. In addition, blocks 300 to 370
Usually depends on the host computer and
It is executed by a computer. However, adapter microcode 380 typically depends on and is implemented by the graphics adapter. In some cases, adapter microcode is loaded into the graphics adapter by the host computer during initialization of the graphics adapter.

In a typical graphics system, a user commands a graphics application to create an image from a 2D or 3D model. First, the user selects the position and type of light source. The user then commands the application software to create the desired model from a given object or user-defined set of objects. Each object can have one or more coplanar drawing primitives that draw the object. For example, a set of drawing primitives, such as multiple triangles, can be used to represent the surface of an object. The user then makes a perspective view in the window to see the model and decides on the desired image. The application software then initiates the rendering of the image from that model by sending the drawing primitives that draw the object to the adapter microcode through the device driver if API, GAI, and DMA are not used.
The adapter microcode renders the image on the graphics display by clipping (ie, cropping) drawing primitives outside the window, and the adapter microcode renders each remaining drawing primitive to the user. Decompose into a visible pixel from the perspective image provided by. Pixels are then loaded into the frame buffer, often in the case of a three-dimensional model by the use of deep buffers. This step is very computationally intensive with a number of associated drawing primitives, variables, pixels, etc. You can store graphics in the frame buffer,
The image displayed on the display usually does not carry the original information such as which drawing primitive or object the pixel was derived from. As a result, the image needs to be re-rendered, either partially or entirely in the window, and the user's perspective, model, light source, etc. are modified.

The technique of the present invention can be used in many locations, such as adapter microcode on the adapter frame buffer side. Also, this approach is relatively quick and easy to implement. Further, the present invention is applicable to graphics application software, and the representation image is also stored in the system memory before or after the representation by the graphics adapter that passes the data backup to the graphics application software. Let Although this approach is slow, it allows existing graphics adapters to utilize the techniques of the present invention. The present invention may also be implemented in the hardware of a graphics adapter processor. This approach is extremely quick, but requires special hardware. As will be apparent to those skilled in the art of the present invention, the present invention is applicable to many other locations within a host computer or graphics adapter.

Most graphics images can be represented as objects, where each object has multiple sets of vertices, or polygons. For example, FIG. 3 shows a set of lines (each line having two vertices) rendered to create an image of a rod-shaped person 410 attempting to pick a ball 420 displayed in the display area 400. Display area 400 may be the entire display, the display portion of the window shown on the display, or another form apparent to one of ordinary skill in the art. Furthermore, the display area may have a shape other than a rectangle, such as a circle.

Although the display area is only a small portion occupied by graphic objects, post-rendering processing of the rendered image, such as sharpness or color comparison adjustment, is typically performed on the entire display area.

FIG. 4 shows a display area with an image of a rod-shaped person 410 attempting to pick up a ball 420. In this example, a display
The area is divided into 128 pixels in the width direction and 112 pixels in the height direction, for a total of 14336 pixels, which is required to be performed using conventional post-processing techniques for rendering. For clarity, pixel addresses are described using lower case x, y, and display area addresses are described using upper case x, y.

The display area 400 is divided into 56 different display areas, each area having 256
It has (16 × 16) pixels. By dividing the display area into regions of 16 pixels in the height direction and 16 pixels in the width direction, the region X and Y addresses are the same as the most significant bits of the addresses of the pixels located in the region. That is, any binary pixel
The display area address (X, Y) is obtained by taking the address (x, y) and moving the x, y address to the right by 4 bits. By creating the width and height of all display areas, a factor of two, the display area address is quickly calculated from any pixel address.

In the preferred embodiment, only the areas that can be modified in the representation of the stick man 410 and the ball 420 are flagged as on, and only those areas of the on flag are processed during the post-expression processing. In the example of FIG. 4, only nine display areas ([X, Y] = [2,5],
[3,2], [3,3], [3,4], [3,5],
[4, 2], [5, 6], [5, 7]), which need to be handled in the post-expression postprocessing in total 220.
It is 4 pixels. This is significantly less than the 14336 pixels above. Of course, one of ordinary skill in the art will appreciate that the display area can be divided into regions of various sizes and shapes without compromising the advantages of the present invention.

FIG. 5 is a block diagram showing the data structure used in the graphics adapter memory 230 in the preferred embodiment of the present invention. Area buffer 231
Indicates which area of the display area is
Used to store flags that indicate what can be modified when rendering an area. In this example, the region buffer is 1280 pixels in the x direction (horizontal direction) and y direction (vertical direction).
Used to represent a display area having 1024 pixels. Further, in this example, the display is divided into regions having a width of 32 pixels and a height of 32 pixels, 40 regions in the X direction and 32 regions in the Y direction for a total of 1280 regions. In the preferred embodiment, the region buffer has a single bit or flag for each region. Each bit or flag indicates whether the corresponding area is modified during image representation. In this example, since there are 32 regions in the Y direction, a single word stored in memory can be used to store a flag for each region in the Y direction. Furthermore, 40 in the X direction
Because of the area, 40 words, each word having 32 bits, can be used to store all flags for the entire area of the display. That is, these words and the flags they contain are quickly turned on and checked quickly to determine if a particular region can be modified in the presentation of the image.

Similar to the regions described in connection with FIG. 4 above, each region is 32 pixels wide and 32 pixels high (two factors) for a total of 1024 pixels for each region, so the address of one region is simply each binary pixel. It can be quickly determined from the pixel address by removing the least significant 5 bits of the address.

Although a single region buffer has been described with respect to FIG. 5, multiple region buffers can be used, especially in a windowing environment. That is, a separate region buffer is used for each window area.

The following flow chart illustrates how a region buffer is created and used to quickly process a graphic image rendered from an object.

FIG. 6 is a flow chart showing how to create a region buffer describing a region extent of a representation image according to a preferred embodiment of the present invention. This procedure is preferably performed when rendering the image, such as after rasterizing the image object into spans or lines, but can be performed when all the vertices of the image object are valid.

Initially, step 600 initializes the region buffer to all zeros, indicating that no region is currently modified.

At step 610, the vertices of one object are received for processing. In step 620, the extent of the object is determined by finding the minimum, maximum x, y pixel addresses of all object vertices. The use of extents for an object is known and is usually defined as a rectangle, which encloses the object at the corners of the rectangle that are the minimum, maximum x, y values of the object's vertices.

In step 630, the object extent is used to determine which region intersects the object. That is, as shown in FIG.
0 and its extent are two areas ([X, Y] =
[5, 6] and [5, 7]). Furthermore, Stickman 4
The right arm of 10 has three regions ([X, Y] = [2, 5],
[3,4] and [3,5]), but the extent of the arm is four areas ([X, Y] = [2,4], [2,
5], [3, 4] and [3, 5]). In the preferred embodiment, in terms of efficiency, the area of intersection using object extents (4 areas for this right arm)
To decide. In another embodiment, it is possible to determine exactly where the area that intersects the object itself (eg 3 areas for the right arm). However, this method of accurate determination is time consuming and is generally undesirable when the object to be represented is of small size.

In steps 620 and 630, the complete x, y address for each vertex is not required. In this example, the least significant 5 bits of the address are dropped to generate the region address, so the least significant 5 bits of each vertex address can be dropped anywhere during this step.

In step 640, it is determined whether the area of intersection with the current object is the same as the area of intersection with the previously represented object. This is a simple test to reduce the number of operations needed in some cases. That is, if the current object is in the same region as the previous object, the appropriate flags for both objects are already on and the current object does not need any further processing.

If YES in step 640, the process continues to step 670, which will be described later. If NO, step 650.
followed by.

In step 650, a buffer word indicating which area intersects the extent of the current object is generated. For example, if the extent of one object intersects the area having the address [X, Y] = [15,16], the 16th bit of the buffer word is on (1
Set to 0) and all other bits are off (set to 0). Then in step 660, the generated word is OR'ed with the corresponding word in its region buffer. In this example, if [X, Y] = [15,16], the 15th word of the area buffer is ORed with the word generated in step 650. Finally, the 16th bit of the 15th word of the region buffer is turned on regardless of whether that bit was already turned on by the previous object. In addition, the other bits in the 16th word are not modified because the OR operation is done on the word generated. Then, the process proceeds to step 670.

In step 670, it is determined whether the last object is accepted to determine which area intersects the image object. If NO, return to step 610 to accept the vertex of the next object. If YES, the process ends.

FIG. 7 is a flow chart showing how the generated data structure is used in the post image rendering processing according to the preferred embodiment of the present invention.

In step 700, the region buffer word is read. Referring to FIG. 5, this is a certain X value of 3
It is one of the horizontal 32 bit words with 32 flags for two regions. Next, in step 710, it is determined if this word is zero. If YES, there is no image object that intersects the display area corresponding to this area buffer word, and the process proceeds to step 770 described later. If NO, the image object intersects with at least one of the corresponding display areas, and thus the process proceeds to step 720.

In step 720, it is determined whether the low order bit of the buffer word is one. If NO,
Since the display area corresponding to that bit or flag has not been modified by any of the image objects, step 750 is entered. If YES, then the display area corresponding to that bit or flag has been modified by any of the image objects, so step 730 is entered.

In step 730, the extent of the display area corresponding to the flag is calculated in the form of a pixel address. This allows for rapid processing of pixels in the display area. In step 740, the area extent is used to process all pixels in the display area. As mentioned above, this process includes sharpness adjustment, color comparison adjustment, zooming, window movement,
Alternatively, it is possible to perform an operation such as a type of processing all the pixels modified in the image representation processing.

Once step 740 is complete, the process moves to step 750. At step 750, it is determined whether the last bit of the region buffer word has been processed. If no, then in step 760 the region display word is shifted to the right by one bit and returned to step 720. If yes,
Moving to step 770, it is determined whether the final area display word has been processed. If NO, the process returns to step 700, and if YES, the processing of this area display buffer is completed.

In another embodiment, a method of handling only a part of the total number of objects at a time can be used. Then, a part of the object is processed as described above, and the above process for another part is repeated. This is especially useful when the number of objects that can be processed in a given time is less than the total number of objects. This is also useful in multi-processor systems where each processor handles a portion of the total number of objects independently of the other processors.

In another process, once the display area is obviously larger in size, but once the display area has multiple objects that intersect a particular display area, the display area is further divided into display sub-areas. Can be made.

In summary, the following matters will be disclosed regarding the configuration of the present invention.

(1) In a device for determining an area extent of an image containing a plurality of graphic objects, a means for dividing a display area into a plurality of display areas, and a display which may intersect with the plurality of graphic objects. Determining an area extent of an image, comprising means for determining which area and means for storing an indicator in a memory corresponding to a display area determined to intersect at least one of said graphic objects. Device to do. (2) The apparatus according to (1), wherein the dividing means includes dividing the display area into a plurality of display areas each having a display area having a plurality of pixels. (3) The apparatus according to (2), wherein the dividing means includes dividing the display area into display areas in which the width and height of each display area are two factors. (4) The apparatus according to (1), wherein the determining means includes calculating an extent of each graphic object and determining which display area intersects each calculated extent. (5) The apparatus according to (1), wherein the storing means includes storing an indicator in a memory corresponding to each display area determined to intersect with at least one of the graphic objects. (6) The device of (5), further comprising means for processing only pixels located in the display area having the corresponding indicia stored in memory. (7) In a method of determining an area extent of an image including a plurality of graphic objects, a step of dividing a display area into a plurality of display areas and a display area that may intersect with the plurality of graphic objects are included. And a step of storing an indicator in a memory corresponding to a display area determined to intersect at least one of the graphic objects. (8) The method according to (7), wherein the dividing step includes dividing the display area into a plurality of display areas each having a display area having a plurality of pixels. (9) The method of (8), wherein the dividing step comprises dividing the display area into display areas in which the width and height of each display area are two factors. (10) The method according to (7), wherein the determining step includes calculating an extent of each graphic object and determining which display area intersects each calculated extent. (11) The method of (7) wherein the storing step comprises storing an indicator in a memory corresponding to each display area determined to intersect with at least one of the graphic objects. (12) The method of (11), including the step of processing only those pixels located in the display area having the corresponding indicia stored in memory. (13) The memory includes a memory for storing data to be processed, a processor for processing the data stored in the memory, and a graphics processing device for determining an area extent of an image made from a plurality of graphic objects. A processing device, i) means for dividing the display area into a plurality of display areas, and ii) means for determining which display area may intersect with the plurality of graphic objects,
iii) at least one of said graphic objects
Means for storing the indicia in a memory corresponding to the display area determined to intersect the individual.

[0045]

The present invention has many advantages, for example, computer processing after image representation, such as sharpness and tone adjustment, is performed only on the area in which the object is represented, thereby making it necessary. It is possible to reduce the number of post-expression operations performed. Furthermore, the present invention provides an effective technique that can be performed simply and quickly when expressing an image. In addition, the present invention is flexible in handling many of the above optimization techniques.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional digital computer used in a preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating layers of code typically used by a host computer and graphics adapter to perform graphics functions.

FIG. 3 is a schematic diagram showing a set of lines represented to create an image displayed in a display area.

FIG. 4 is a schematic diagram showing a set of lines represented to create an image displayed in a display area divided into a plurality of display areas.

FIG. 5 is a block diagram showing a data structure used in a graphics adapter memory according to a preferred embodiment of the present invention.

FIG. 6 is a flowchart showing how to generate a data structure describing a region extent of a representation image according to a preferred embodiment of the present invention.

FIG. 7 is a flow chart showing how the generated data structure is used in the image representation post-processing according to the preferred embodiment of the present invention.

[Explanation of symbols]

100 Digital Computer 105 Computer Box 110 Main Processor 120 Memory 125 Hard Disk 130 Input Device 140 Output Device 150 Graphics Output Device 160 Bus 170 Input / Output Device Controller 180 Input / Output Device 190 Removable Medium 200 Graphics Adapter 220 Graphics Adapter Processor 230 Graphics Adapter Memory 231 Area Buffer 250 RAMDAC 300 Operating System 310 Operating System Core 320 Host Computer Microcode 330 Graphics Application 332 Graphics Application 340 Application Program・ Interface 342 Application program interface 350 graphics application interface 352 graphics application interface 370 graphics adapter device driver

 ─────────────────────────────────────────────────── ——————————————————————————————————————— Inventor Allen Peter Jansen United States 78758 Shady Springs 11901 Austin Texas

Claims (13)

[Claims] 1. A device for determining an area extent of an image including a plurality of graphic objects, a means for dividing a display area into a plurality of display areas, and a display area which may intersect with the plurality of graphic objects. Determining the area extent of the image, comprising means for determining which is, and means for storing an indicator in a memory corresponding to the display area determined to intersect at least one of said graphic objects. apparatus. 2. The dividing means is the display.
The apparatus of claim 1 including dividing the area into a plurality of display areas each having a display area having a plurality of pixels. 3. The display is divided by the dividing means.
3. The apparatus of claim 2 including dividing the area into display areas where the width and height of each display area is a factor of two. 4. The method according to claim 1, wherein the determining means includes calculating an extent of each graphic object and determining which display area intersects each calculated extent. apparatus. 5. The method of claim 1 wherein the means for storing includes storing an indicator in a memory corresponding to each display area determined to intersect with at least one of the graphic objects. apparatus. 6. The apparatus of claim 5, further comprising means for processing only pixels located in a display area having a corresponding indicia stored in memory. 7. A method of determining an area extent of an image containing a plurality of graphic objects, the method comprising: dividing a display area into a plurality of display areas; and a display area that may intersect with the plurality of graphic objects. Determining an area extent of an image, the method comprising: determining which is an image, and storing an indicator in a memory corresponding to a display area determined to intersect at least one of the graphic objects. Method. 8. The method of claim 7, wherein the dividing step comprises dividing the display area into a plurality of display areas each having a display area having a plurality of pixels. 9. The method of claim 8, wherein the dividing step comprises dividing the display area into display areas where the width and height of each display area is a factor of two. . 10. The method according to claim 7, wherein the determining step includes calculating an extent of each graphic object and determining which display area intersects each calculated extent. Method. 11. The method of claim 7, wherein the storing step includes storing an indicator in a memory corresponding to each display area determined to intersect with at least one of the graphic objects. Method. 12. The method of claim 11 including the step of processing only those pixels located in the display area having the corresponding indicia stored in memory. 13. A memory for storing data to be processed, a processor for processing the data stored in the memory, and a graphics processing device for determining an area extent of an image created from a plurality of graphic objects, The graphics processing device comprises: i) means for dividing a display area into a plurality of display areas; ii) means for determining which display areas may intersect with the plurality of graphic objects; iii. ) At least one of said graphic objects
Means for storing the indicia in a memory corresponding to the display area determined to intersect the individual.