JPH05189575A - Bit map expansion system - Google Patents

Abstract

PURPOSE:To increase the processing speed by dividing each graphic element by a specific division line prior to the expansion to bit map data and generating vector data with respect to each divided element. CONSTITUTION:The plotter command stored in a buffer 2 for input data is successively supplied to a command analyzing part 3, and the part 3 analyzes the plotter command, and the analysis result is supplied to a vector data converting part 4. The vector dividing part 4a of the vector data converting part 4 divides graphic elements of the given command analysis result for example, at every band and generates vector data with respect to each divided element. Vector data stored in a buffer 5 for vector data is expanded to a bit map in a band unit by bit map expansion part 6, and expanded bit map data is stored in, for example, a bit map memory 7 having 2M-byte capacity and one-band width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bitmap expansion method for generating bitmap data from a plotter command output from a host computer or the like, and particularly to image information corresponding to one drawing in a plurality of bands. The present invention relates to a banding type bitmap expansion method that divides and expands the bitmap for each band.

[0002]

2. Description of the Related Art Pen plotters are commonly used as drawing devices in automatic drawing systems.
Raster type drawing devices such as thermal printers and laser printers, which are excellent in printing speed, have also been frequently used. In this case, from the host computer,
Since plotter commands intended for pen plotters are often output, bit map data is generated from the plotter commands in the input interface of these raster drawing devices in order to ensure compatibility with pen plotters. In order to do so, a bitmap expansion means is required. By the way, for example, when storing an A0 size drawing at a resolution of 400 dots / inch, the required capacity of the bitmap memory reaches 30 Mbytes.
For this reason, if a bitmap memory corresponding to all pixels is used in a large-sized drawing device such as A1 or A0 size, a large cost increase is incurred. For this reason, one drawing is divided into a plurality of bands, and bitmap expansion is performed in band units to reduce the capacity of the bitmap memory used to, for example, approximately 2 Mbytes. Banding type bitmap The deployment method is also known.

[0003]

However, in the conventional banding type bitmap expansion method, even if the bitmap expansion is performed for each band, the information given to the bitmap expansion means is the start point and end point of the graphic element. Since it is limited to information such as the center point and radius, it is difficult to recognize the band boundary and perform processing. For example, even when using a graphic processor with dedicated commands to perform bitmap expansion, clipping is applied to the unprintable area to handle the banding process without increasing the software load, and Bitmap expansion is performed. For this reason, conventionally, there is a problem that it takes time to output a bitmap because the bitmap expansion is performed even for an area that originally does not require expansion.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a bitmap expansion method capable of significantly increasing the processing speed in the above-mentioned banding type bitmap expansion processing method. To do.

[0005]

A bitmap development device according to the present invention divides image information corresponding to one drawing into a plurality of bands, and converts vector data of graphic elements into bitmap data for each band. In the bitmap expansion method for expanding the graphic elements, each graphic element is divided by a specific dividing line or a plurality of dividing lines, vector data is generated for each divided element of the graphic elements, and then these vector data are bit It is characterized by expanding to map data.

[0006]

According to the present invention, each graphic element is divided by a specific dividing line or a plurality of dividing lines prior to expansion into bitmap data, and vector data is generated for each divided element. Therefore, for example, when the graphic element is divided into bands, the expansion area of one vector data is only one band, and when the graphic element is divided into two bands,
The expansion area of graphic elements is reduced such that the expansion area of one vector data is only two bands. Therefore, the processing speed of bitmap expansion can be significantly improved.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a functional block diagram showing the configuration of a bitmap expansion system according to an embodiment of the present invention.

A plotter command given from a host computer or the like is stored in the input data buffer 2 via the interface circuit 1. The plotter command stored in the input data buffer 2 is
It is sequentially supplied to the command analysis unit 3. The command analysis unit 3 analyzes the input plotter command, and the analysis result is supplied to the vector data conversion unit 4. The vector data conversion unit 4 is provided with a vector division unit 4a that divides the given graphic element of the command analysis result into, for example, each band and generates vector data for each divided element. The obtained vector data is once stored in the vector data buffer 5. The vector data stored in the vector data buffer 5 is supplied to the bitmap expansion unit 6. The bitmap expansion unit 6 expands the vector data into bitmaps in band units. The bit map data expanded by the bit map expansion unit 6 is stored in the bit map memory 7 having a capacity of 2 Mbytes and one band width, for example.

Next, the operation of the bitmap expansion system configured as described above will be described. FIG. 2 is a diagram showing an outline of a plotter command supplied to this bitmap expansion system. As shown in the figure, the plotter command is made up of a pen up / down command, coordinate values of the moving destination, a pen number (not shown), information specifying the type of graphic element, and the like. When such a plotter command is input into the system from the host computer via the interface circuit 1, the plotter command is temporarily stored in the input data buffer 2. When a predetermined number of plotter commands are stored in the input data buffer 2,
The command analysis unit 3 is activated and command analysis is performed. In this command analysis, the coordinate values of the start point and the end point are decomposed from the plotter command. This decomposition is mainly performed by the pen down command. For example, "DOWN (x
2, y2) "is given, the end point coordinate value (x2, y2) is saved as the end point coordinate value and the immediately preceding command" UP (x1, y1) "is given.
The coordinate value (x1, y1) of the end point of is stored as the start point coordinate value.

When the plotter command is analyzed, the vector data conversion unit 4 is activated next, and the vector data of each graphic element forming the image data is generated from the analysis result of the command analysis unit 3. The procedure for generating this vector data is shown in FIG. That is, first, the command analysis result is input (S1), and the end point coordinate value is set to the end point coordinate value (xe,
Save as "yes" (S2). When the input command is the DOWN command (S3), the end point coordinate value of the immediately preceding command is set to the start point coordinate value (xs,
ys) (S4), and if not, the next command analysis result is input. In the case of the DOWN command, the band including the graphic element is subsequently calculated (S
5). For example, in the case of the straight line 10 shown in FIG. 4, the start point coordinate value (xs, ys) is the 0th band and the end point coordinate value (x
e, ye) is included in the third band, the band including this graphic element (straight line) is 0, 1,
This is the second and third band. Next, each graphic element is divided along a dividing line (a band boundary in this example) to create vector data for each band (S6). FIG. 4 shows that the straight line 10 is divided into four straight lines, and FIG. 5 shows the vector data obtained at that time. The vector data 11 includes information 11a indicating the type of graphic element, band information 11b, start point information 11c, and end point information 11d. The straight line 10 represented by (xs, ys)-(xe, ye) is (xs, ys)-(x1, y1
), (X1, y1)-(x2, y2), (x2, y2)
)-(X3, y3), (x3, y3)-(xe, ye
) Is divided into four straight lines.

The vector data thus divided is temporarily stored in the vector data buffer 5 and then supplied to the bit map expanding section 6. The bitmap expansion unit 6 expands the supplied vector data into a bitmap.
That is, first, vector data is input, and it is determined whether or not the vector data is included in the band currently being processed. If the current band is not included, the subsequent process is not performed and the next vector data is input. If it is included in the current band, bitmap expansion is performed. As a method of expanding the bitmap, a DDA (digital differential analog) based on the start point coordinate value and the end point coordinate value is used.
The well-known algorithms of Lyzer), Bresenham et al. can be used.

As described above, according to this embodiment, since the graphic element is divided into each band to generate the vector data, the area in which one vector data is expanded into the bitmap is always one band. Limited to within. Therefore, it is possible to prevent the execution of unnecessary expansion processing and improve the processing speed without changing the software of the graphic processor.

FIG. 6 is a diagram for explaining the second embodiment of the present invention, and is a schematic diagram for explaining the embodiment in the case of performing the arc processing for shaping the line end portion. In this embodiment, assuming that the line width of the straight line 20 which is a graphic element is W, the dividing lines shown by the dotted line in the drawing for dividing the straight line 20 are the first, second, and
W / 2 from the boundary with the succeeding band in the third band
However, the positions are set to the positions y2 ', y3', and y4 'in front. That is, when the arc processing is performed on the line end portion, an arc having a radius of W / 2 is drawn at the position of the line end portion, so that the end portion of the actually drawn area is W more than the line end position. It projects by / 2. Therefore, if the end points of the line are located in the area between the line preceding by W / 2 from the boundary of each band and the boundary line of the band, when the line is divided by the boundary line, it is drawn by arc processing. The part that should be played will fall on the next band, so that part will be missing. Therefore, if the division is performed at the position shown by the dotted line in FIG. 6, such a problem of the missing line end does not occur. In this embodiment, the bitmap expansion process covers two bands, but it is clear that the processing speed is significantly improved as compared with the conventional case where the entire region is covered. From these facts, according to the present system, the processing speed of bitmap expansion can be significantly improved as compared with the conventional system.

The present invention is not limited to the above embodiment, and the position of the dividing line, the number of divisions, etc. can be set arbitrarily.

[0015]

As described above, according to the present invention,
Prior to expanding to bitmap data, each graphic element is divided by one or more specific dividing lines, and vector data is generated for each divided element, so the expansion area of the graphic element is reduced and The processing speed of expansion can be greatly improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a bitmap expansion system according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a plotter command input to the system.

FIG. 3 is a flowchart showing a vector data conversion process in the system.

FIG. 4 is a schematic diagram showing division positions of graphic elements in the system.

FIG. 5 is a schematic diagram showing how vector data is divided in the same system.

FIG. 6 is a schematic diagram showing division positions of graphic elements in the bitmap expansion system according to the second example of the present invention.

[Explanation of symbols]

1 ... Interface circuit, 2 ... Input data buffer,
3 ... Command analysis unit, 4 ... Vector data conversion unit, 4a ...
Vector division unit, 5 ... Vector data buffer, 6 ... Bit map expansion unit, 7 ... Bit map memory.

Claims (2)

[Claims] 1. A bitmap expansion method in which image information corresponding to one drawing is divided into a plurality of bands, and vector data of graphic elements is expanded into bitmap data for each band, wherein each graphic element Is divided by a specific one or a plurality of dividing lines, vector data is generated for each of the divided graphic elements, and the vector data is expanded into bitmap data. .. 2. When the total number of the bands is N and the line width of the graphic element is W, the dividing line of the graphic element is a boundary line between the second band and the succeeding band in the (N-1) th band. 2. The bitmap expansion method according to claim 1, wherein the divided graphic elements are set to the front side from W / 2 to W / 2, and each of the divided graphic elements extends over two bands.