JPH1049690A - Picture forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture forming device in which necessary memory amounts are small, and the load of data transfer is small. SOLUTION: An inputted picture plotting instruction is interpreted and executed by a plotted graphic description generating means 1, and plotted graphic description to which an identifier for specifying a graphic and the information of the priority order of overlapping is added is generated. This plotted graphic description is registered in a graphic description holding means 2. Then, a description updating means 3 checks the interference relation of a plotted area with the plotted graphic description registered until then, adds cross-point information constituted of the identifier for specifying an overlapping graphic element and a cross-point coordinate to the element graphic description of the plotted graphic in the lower priority order of overlapping for the plotted graphic hidden in the overlapping relation with another plotted graphic, and optimizes the cross-point information from the cross-point information. The plotted graphic description is vectorized by a vector data generating means 4, and turned into output data in a printable form by an output processing means 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus which executes an instruction sequence described in a language for expressing a document to form an image information and optimizes a description of an overlap between figures constituting an image. The present invention relates to an image forming apparatus to be formed.

[0002]

2. Description of the Related Art A page description language program expressing a document is sequentially interpreted and executed by a printer, and when a command indicating the end of a page is executed, actual printing is performed. For this purpose, the printer has a buffer for holding at least one page of images, executes a drawing command on this buffer, and forms printable image data.

In such a conventional configuration, as the resolution of the output device increases, the amount of print data increases, the cost of the entire system increases due to an increase in the buffer capacity, and the speed increases due to an increase in the amount of data transfer in the system. It has led to a decline. Further, since the processing of expanding and superimposing the components of the page is performed at the level of the printable image data having a large data amount, the processing load on the image forming apparatus is also increasing.

On the other hand, priority is given to an image drawing command of a page description language, and when a certain drawing command is developed, a pixel which has already been developed by an instruction having a higher priority than that command is not overwritten. Japanese Patent Laid-Open No. 6-119456 proposes a method for improving the efficiency of the expansion processing. In this expansion processing method, since the method of detecting overlap is performed by referring to pixels, it is necessary to hold a buffer having a large capacity in the image data format.

[0005] Further, as another form of the superposition processing,
2. Description of the Related Art There is insertion printing in which a plurality of originals differing only in part of data are superimposed on a common original and printed using an overlay process or the like. In the insertion printing, a process of storing the page data created beforehand and synthesizing this with data corresponding to the changed portion to create print data is performed. When this synthesizing process is performed at the level of printable image data, a large amount of memory and a high-speed arithmetic device are similarly required.

In order to avoid this, it is necessary to devise a synthesis process. The methods proposed in JP-A-4-250582 and JP-A-4-282784 are designed to efficiently perform overlapping processing of graphics on scan lines constituting a page. Therefore, only page data in pixel format can be output, and when overlay processing or the like is applied to this output, a large amount of memory and a high-speed arithmetic device are also required.

In any case, in the conventional superimposition processing, the result of superimposition of graphics is expressed at the level of printable image data having a large data amount. In order to cope with this, it is necessary that the overlapping of the figures is appropriately expressed at the level of the graphic description having a higher level of abstraction than that of the printable image data, and is also required at the level of the graphic description having a higher level of abstraction. A mechanism for processing the overlap of the expressed graphic description is required.

In the case of processing such overlapping graphic descriptions, when a small graphic is completely hidden by a large graphic, the small graphic is erased (reduced) or the first graphic crosses the second graphic. When the first figure is divided when it overlaps as described above, in order to degenerate or divide the figure description according to the overlap, the figure description after the processing of the degeneration or division accurately holds the overlapping boundary of the figure. Need to be. Otherwise, an error may cause pixels to drop out near intersections and boundaries or cause incorrect overlap. For this purpose, it is necessary to calculate an accurate intersection using an iterative calculation as proposed in JP-A-4-222060.

[0009]

As described above, in the conventional image forming apparatus, since the overlap generated by the interference between the drawing areas of a plurality of figures is not properly expressed and processed as the relation between the figures, A large amount of memory is required when trying to optimize the overlapping of descriptions for individual descriptions or to reduce the problem of finding a color change point of a pixel on a scan line. Since the data transfer is performed, the load of the data transfer is large, and there is a problem that the calculation load of the system increases for calculating the intersection accurately. In order to solve this, it is necessary to establish a graphic description capable of expressing the overlapping relationship and a processing method thereof. At this time, it is necessary to refer to the internal structure of the interfering figures in order to identify the position of the overlapping of the interfering figures, but if the graphic description is degenerated or divided by the overlapping processing, accurate reference cannot be performed. You must also pay attention to the points.

[0010] The present invention has been made in view of such a point, and requires a small amount of memory for image formation.
An object of the present invention is to provide an image forming apparatus having a small data transfer load.

[0011]

According to the present invention, in order to solve the above-mentioned problems, in an image forming apparatus for obtaining an output image by executing an image drawing command described in a page description language, A drawing graphic description generating means for interpreting a drawing command and generating a drawing graphic description including a sequence of directed straight lines and directed curves representing the outline of the drawing graphic, a drawing graphic identifier, and an overlap priority; A graphic description holding means for holding the drawing graphic description generated by the description generating means; and the drawing graphic so as to add overlapping information to the drawing graphic description based on the overlapping relationship of the drawing graphic description held by the graphic description holding means. Description updating means for updating the description; vector description generating means for generating a vector description from the drawing graphic description held in the graphic description holding means; Image forming apparatus is provided which is characterized in that an output processing means for generating output data printable format using a vector description generated by the means.

According to such an image forming apparatus, a drawing figure description such as a line segment or a curve constituting the drawing figure description generated by the drawing figure description generation means and held in the figure description holding means is added to the drawing figure description. The description updating means adds overlap information of an identifier for specifying another overlapping drawing figure and coordinates of an intersection. By determining intersections and boundaries at the pixel level using this overlapping information, that is, by performing the overlapping processing not with the level of the image data having a large data amount but with the drawing graphic description with a higher abstraction level In addition, it is possible to suppress an increase in the capacity of the buffer, and to avoid pixel omission or incorrect overlap near an intersection or a boundary due to an error. Also, by using the drawing graphic description generated in this way, it is possible to suppress the memory usage of the printer system and the load of data transfer during overlay processing or the like.

Further, according to the present invention, in an image forming apparatus for executing an image drawing command described in a page description language to obtain an output image, the image forming apparatus interprets the input image drawing command and generates Drawing graphic description generating means for generating a drawing graphic description composed of a sequence of directed straight lines and directed curves representing an outer shape, a drawing graphic identifier, and an overlap priority;
Vector description generating means for generating a vector description from the drawing graphic description generated by the drawing graphic description generating means, vector description storing means for storing the vector description generated by the vector description generating means, and the vector description storing means Description updating means for updating the vector description so as to add overlap information to the vector description based on the overlapping relationship of the vector descriptions held by the information processing apparatus, and a format printable using the vector description held by the vector description holding means And an output processing means for generating the output data.

According to the above arrangement, after the drawing graphic description is generated by the drawing graphic description generating means and the vector description is generated by the vector description generating means, the elements constituting the vector description held in the vector description holding means are generated. The description updating means adds overlap information of an identifier for specifying another element vector that intersects the element vector and the coordinates of the intersection to the description of the vector. By determining intersections and boundaries at the pixel level using this overlapping information, that is, by performing overlapping processing not with the level of image data having a large data amount but with a vector description having a higher level of abstraction, In addition to suppressing an increase in the capacity of the buffer, it is possible to avoid omission of pixels and incorrect overlapping near intersections and boundaries due to errors. In addition, by using the graphic description generated in this way, it is possible to suppress the memory usage of the printer system and the data transfer load during the overlay processing or the like.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the principle configuration of the first invention. An image forming apparatus according to the present invention includes a drawing graphic description generating means 1 for receiving an image drawing command, a graphic description holding means 2 for storing the drawing graphic description generated by the drawing graphic description generating means 1, and a graphic description holding means A description updating unit 3 for performing an update process based on the overlapping relationship with the drawing graphic description held by the graphic description holding unit 2 and a vector description generating unit 4 for generating a vector description from the drawing graphic description of the graphic description holding unit 2
An output processing unit 5 for outputting pixel-level output data from the vector description of the vector description generation unit, a drawing figure description of the figure description holding unit 2 is saved, and the saved drawing figure description is held in the figure description. And a secondary storage means 6 for outputting to the means 2.

In this configuration, the input of the image drawing command described in the page description language is performed by the drawing figure description generating means 1.
And a drawing figure description representing the drawing figure is generated. This drawing figure description includes information for an element figure such as an identifier for specifying the figure, an overlapping priority, and a line segment or a point constituting the figure.

The drawing graphic description generated by the drawing graphic description generating means 1 is sent to the graphic description holding means 2. In the graphic description holding means 2, a new description is registered, and at the same time, the description updating means 3 checks the interference of the drawing area with the drawing graphic description registered so far. As a result, for a drawing graphic that has a low priority of overlapping among the drawing graphics that interfere with each other and falls below in the overlapping relationship with another drawing graphic, the description updating unit 3 configures the directed graphics that constitute the drawing graphic. For each element figure description of a straight line or directed curve, a drawing figure for specifying an element figure overlapping with the element figure, an identifier of the element figure, and coordinates of the intersection are added.

The description updating means 3 first performs alignment of the obtained intersection description in consideration of the orientation of the element graphic. In this method, the increase / decrease in the direction of each coordinate axis is checked from the coordinate values of the end points of the element graphics, and based on the increase / decrease, it is determined whether the elements are to be arranged in ascending or descending order, and lexicographical sorting is performed in this order. Next, the description updating means 3 includes, among a plurality of intersection descriptions appearing in one element graphic description, a plurality of intersection descriptions with the same drawing figure, which overlaps with the drawing figure and has a lower priority. The intersection description is optimized by deleting the intersection description. By repeating the above operation until an instruction indicating the end of the page is detected, a graphic figure description for one page including overlapping information is generated in the graphic description holding unit 2.

The drawing graphic description thus generated is converted into vector data by the vector data generating means 4. This vector data reflects the intersection description,
It does not include information about the part under the overlap with other drawing figures.

The vector data is sent to the output processing means 5 for output processing, and outputs printable format output data. When performing output processing using vector data,
Since it is not necessary to perform the superposition processing at the pixel information level, the amount of data to be handled can be suppressed.

When performing overlay processing, etc.,
1 including the overlap information generated by the graphic description holding means 2
The drawing graphic description for the page is temporarily saved in the secondary storage unit 6. Here, when a new image drawing command is input, the drawing figure description saved in the secondary storage means 6 is first read into the figure description holding means 2. The read drawing figure description becomes an initial value of the overlap processing with the drawing figure description based on the new image drawing command. Also in this case, it is not necessary to perform the superposition processing at the pixel information level, so that the amount of data to be handled can be suppressed.

FIG. 2 is a diagram showing the principle configuration of the second invention. The illustrated image forming apparatus includes a drawing figure description generating unit 11 that receives an image drawing command, and a drawing figure description generating unit 1.
1, a vector description generating means 12 for generating a vector description from the drawing graphic description generated in step 1, a vector description storing means 13 for storing the vector description generated by the vector description generating means 12, and a vector description storing means 13 Description updating means 14 for performing an updating process on the held vector description based on the overlapping relationship; output processing means 15 for outputting pixel-level output data from the vector description of the vector description holding means 13;
And a secondary storage unit 16 for saving the saved vector description to the vector description holding unit 13.

According to this configuration, the input image drawing command is interpreted and executed by the drawing figure description generating means 11, and the identifier for specifying the figure, the overlapping priority, the line segment and the point constituting the figure, etc. A drawing figure description including the information of the element figure is generated. The drawing graphic description generated by the drawing graphic description generating means 11 is immediately sent to the vector description generating means 12 and subjected to vectorization processing.

Next, the vector description generated by the vector description generating means 12 is held by the vector description holding means 13. In response to the vector description held in the vector description holding means 13, the description updating means 14 inserts an identifier specifying an element vector that intersects this element vector with an identifier and Coordinates are added as overlap information. In addition, the description updating means 14 arranges the intersections appearing in the description of the element vectors constituting the drawing graphic vector in accordance with the direction of the element vector, and if the intersection is located inside the intersection with the figure having a higher overlapping priority among the aligned intersections. The overlap information is optimized by deleting the intersection with the graphic having a lower priority than the graphic. By repeating the above operation until an instruction indicating the end of the page is detected, the vector description holding means 1
In 3, a vector description for one page including overlapping information is generated.

The vector description processed in this way is sent to the output processing means 15 for output processing, and outputs printable format output data. As described above, by storing the vector description in the vector description holding unit 13 and performing the overlapping process on the vector description holding unit 13, it is possible to avoid handling a curve representing a free curve or the like in the overlapping process. , The amount of calculation can be reduced.

Further, the vector description generated in this way is saved in the secondary storage means 16 and is superimposed on the vector description generated from another input, so that a large amount of memory is not used. Overlay processing can be realized.

Next, an embodiment in which the first embodiment of the present invention is applied to a printing system connected to a network will be described as an example. FIG. 3 is a diagram showing a configuration example of a network printing system to which the image forming apparatus according to the present invention is applied. The network printing system includes a plurality of client computers 21, 22, 23,.
, A print server 40, and a print engine 50, and the image forming apparatus according to the present invention is applied as a part of the print server 40. Print server 4
0 is the instruction analysis unit 41 connected to the network 30
, A graphic description updating unit 42, a quantizing unit 43, a page buffer 44, and an output processing unit 45 are mutually connected by a shared bus 46. The print server 40 further includes a printer interface 47 connected to an output processing unit 45, and the output of the printer interface 47 is connected to a print engine 50.

In the network printing system, a print job created by the client computers 21, 22, 23,... Is sent to the command analysis unit 41 of the print server 40 via the network 30. The command analysis unit 41 interprets and executes the contents of the received print job as a command sequence in a page description language, and generates a graphic description representing each drawing graphic. The generated graphic description is stored in the page buffer 44.
Is stored in At this time, if there is an overlap between the graphic already stored in the page buffer 44 and the newly generated graphic, the graphic description is updated by the graphic description updating unit 42 based on the priority of the overlap. . When an instruction indicating the end of the page is detected, the graphic description stored in the page buffer 44 is sent to the quantization unit 43 and vectorized. The vector data output from the quantization unit 43 is sent to an output processing unit 45, where output data in a printable format is generated. Output data output from the output processing unit 45 is sent to the print engine 50 via the printer interface 47 and printed.

The command analysis unit 41 interprets and executes a command sequence of a page description language given as an input in order, and generates a corresponding graphic description. This graphic description includes, in addition to the description of each elemental graphic constituting the graphic, an identifier for identifying the graphic and an overlapping priority as information not described in the given page description language. I have. The description of the element graphic includes the coordinates of the feature points required to define the element graphic. For example, the description of a line segment includes the coordinates of both ends, and the description of a curve
The coordinates of four control points are included. In the present embodiment, it is assumed that the description of the element graphic in the graphic description appears continuously in the counterclockwise order. The description of a certain element graphic can be specified by the identifier given to the graphic description including the element graphic and the appearance order in the graphic description.

The graphic description generated by the instruction analyzing unit 41 is stored in the page buffer 44 in order. here,
When newly registering the first graphic description in the page buffer 44, if the graphic represented by the first graphic description overlaps with the graphic represented by the second registered graphic description,
The graphic description updating unit 42 adds overlapping information to the second graphic description having a lower overlapping priority among those graphic descriptions. The flow of this processing will be described below.

FIG. 4 is a flowchart showing the flow of the processing of the overlap determination procedure. Here, the case of using the circumscribed rectangle of the figure for the overlap determination will be described as an example. And
Let the circumscribed rectangle of two figures be represented by a quadruple of numbers,
Each number is the x of the upper left and lower right points of the rectangle
The coordinates and y-coordinate values are represented.

Therefore, first, the maximum values of the x- and y-coordinates of the upper left point of the two circumscribed rectangles are determined by the variables Lx and Ly.
And the minimum value of the x and y coordinates of the lower right point
x and Hy are set respectively (step S1). Subsequently, comparison is made between variables relating to the x coordinate and the y coordinate of the two circumscribed rectangles (step S2). That is, Lx <Hx
Is determined, and whether Ly <Hy is satisfied. If both are satisfied, it is determined that there is an overlap, and the process ends. If both comparisons are not satisfied, it is determined that there is no overlap, and the processing ends.

The determination of the presence or absence of the overlap becomes possible for the following reasons when two circumscribed rectangles are given. Given an orthographic projection of a rectangular area onto an axis, this forms a wide range of values. If the two ranges overlap, the ends of the overlap region are those on the right of the left boundaries of the two ranges and those on the left of the right boundaries, which appear in this order from left to right. If the two ranges do not overlap, their order of appearance is reversed. The overlap determination procedure in FIG. 4 utilizes such a property.

Next, the next process of the graphic description updating unit based on the result of such overlap determination will be described. FIG. 5 is a flowchart showing the flow of the overlapping information adding process. First, it is determined whether or not the result of the overlap determination indicates that there is overlap (step S11). Here, if it is determined that there is no overlap, this processing ends as it is. If it is determined that there is an overlap, a registered second graphic that interferes with the newly registered first graphic is specified. (Step S12). Next, for each of the element figures constituting the first figure, the element figure of the second figure overlapping with the element figure is specified (step S13), the intersection between the element figures is calculated, and the second figure is calculated. The overlapping information including the information for specifying the element graphic of the first graphic and the coordinates of the intersection is added to the description of the constituent graphic (step S14). At this time, it is not necessary to obtain an exact value for the coordinates of the intersection. For example, a curve segment may be approximated by a line segment connecting the control points.

The above operation is repeated until an instruction indicating the end of the page is detected. When a graphic description for one page is generated in the page buffer 44, the graphic description stored in the page buffer 44 is then added to the graphic description. Optimize the included overlap information. This is a process consisting of two operations on the intersection information. First, the intersection description added to each element graphic description is aligned using the coordinate values of the intersection.
The alignment is performed in lexicographic order using the coordinate values in the two axis directions, and an increase or decrease in each axis direction of the element graphics corresponds to an ascending or descending order. FIGS. 6 and 7 show flowcharts of this procedure.

FIG. 6 is a flowchart showing an example of the flow of the alignment process. First, it is determined whether or not there is overlap information included in the stored graphic description (step S21). Here, if it is determined that there is no overlap information, this processing is terminated as it is, and if it is determined that there is overlap information, among the coordinate values of the vertices constituting the element graphic description, It is determined whether or not the coordinate value is increasing in the x-axis direction (step S22). If the coordinate value is increasing in the x-axis direction, the intersection points of the intersection description added to the element graphic description are arranged in ascending order (step S22). S23) If it is decreasing in the x-axis direction, the intersections are arranged in descending order (step S24). Next, it is determined whether the coordinate value of the intersection with respect to the y coordinate is increasing in the y-axis direction (step S25). If the coordinate value is increasing in the y-axis direction, the coordinates are arranged in ascending order (step S26).
If it decreases in the y-axis direction, it is arranged in descending order (step S27). Then, alignment is performed in dictionary order using the coordinate values in the biaxial directions (step S28). According to the above processing, the intersections are arranged such that the intersections are arranged from the start point to the end point along the direction of the line segment.

Next, intersection information under the overlap with another figure is checked and deleted. This is because when the intersection with the graphic having the overlapping priority r1 is sandwiched between the intersection with the graphic having the priority r2 higher than r1 in the overlapping information added to each element graphic, This is realized by thinking that it is hidden under the overlap with the latter, and removing it. FIG. 7 shows a flowchart of this procedure.

FIG. 7 is a flowchart showing the flow of the optimization process. Here, the intersection information is received in an aligned state. First, the presence / absence of overlapping information is determined for the aligned intersection information (step S31). here,
If it is determined that there is no overlap information, this process is terminated. If it is determined that there is overlap information, the value of the priority variable prio is initialized to 0 (step S32).
Next, the intersection information is scanned in the described order. Here, it is determined whether or not all the intersection information has been scanned (step S33). If all the intersection information has been scanned, the process ends. If all the intersection information has not been scanned, the information of the next intersection (the information of the first intersection) is scanned (step S34). The overlapping priority of the intersection is checked, and the overlapping priority of the currently focused intersection is substituted into another variable p (step S35). Next, this variable p
And the variable prio are compared (step S36). Here, if the overlap priority of the current intersection point of interest is higher than the overlap priority of the comparison target intersection points, the current intersection point cannot be deleted. S37), returning to step S33, and proceeding to the next intersection. If the overlap priority of the current intersection is not higher than the overlap priority of the intersection to be compared, the current intersection is hidden by the overlap and is determined to be an intersection that should not originally come out. The low current intersection is saved (step S38). Next, it is determined whether the variable p is equal to the variable prio (step S3).
9) If not equal, return to step S33,
We will examine the intersections that can be deleted. If the priorities are equal, the intersections that have been evacuated so far are collectively deleted (step S40), and the process returns to step S32.
Proceed to search for the next group of intersections that can be deleted.

Although the above processing is based on a very simple algorithm, it actually matters whether the intersection is inside or outside the figure. If the intersection is outside the figure, the intersection is deleted. I can't. Therefore, in order to perform the optimization processing more strictly, the direction of the intersection of the interfering elemental figures at each intersection position is added to the intersection information, and a non-zero winding number rule or an even-even winding number rule is applied thereto, thereby obtaining an accurate This is realized by performing an inside / outside determination and removing an intersection point between a figure having a higher overlap priority and a figure having a lower overlap priority than that of the figure. FIG. 8 shows a flowchart of this procedure. However, since the internality determination using the winding number rule is implemented in a normal page description language processing device, its details are omitted.

FIG. 8 is a flowchart showing the flow of another optimization process. First, the presence / absence of overlapping information is determined for the aligned intersection information (step S51). Here, if it is determined that there is no overlap information, this processing is terminated as it is, and if it is determined that there is overlap information, the value of the priority variable prio is initialized to 0 (step S5).
2). Next, it is determined whether or not all the intersection information has been scanned (step S53). If all the intersection information has been scanned, the process ends as it is. If not all the intersection information has been scanned, the information of the next intersection is scanned (step S).
54). The overlap priority of the intersection is checked, and the overlap priority of the current intersection is substituted into another variable p (step S5).
5). Next, the variable p is compared with the variable prio (step S56). If the current overlap priority of the intersection is higher than the overlap priority of the comparison target intersection, the variable p is substituted for the variable prio (step S56). S57), Step S53
Return to If the overlap priority of the current intersection is not higher than the overlap priority of the intersection to be compared, an internality determination is performed for the intersection (step S58). In this internality judgment, if it is not inside, that is, if the current intersection is a boundary that goes out of the figure, the figure below must be left, so the variable prio is initialized to 0. (Step S59), returning to step S53. If the current intersection is inside the figure as a result of the internality determination, the current intersection is evacuated (step S60). Next, the variable p
It is determined whether or not is equal to the variable prio (step S61). If not equal, the process returns to step S53. If the priorities are equal, the evacuated intersection is deleted (step S62), and the process returns to step S52.

Subsequently, the graphic description contained in the page buffer 44 is vectorized by the quantization unit 43. This consists of a process of approximating a curve with a minute line segment and a process of determining the end points of the element graphics constituting the graphic. There are various methods for approximating a curve by a minute line segment depending on the curve model. For example, in a Bezier curve model, the distance between the line segment connecting the end points of the curve and the curve is predetermined. By repeating the division recursively until the value of the range is reached, a series of approximate minute line segments is obtained. When the approximation of the curve by the minute line segment is completed, all the elemental figures constituting the figure are reduced to line segments, whereby the calculation of all the intersection points becomes a problem of finding the intersection point of the straight line, and it is easy without repeating the calculation. Accurate intersection coordinates can be obtained. The element graphic description is divided into vectors using the coordinates of the intersection thus obtained. The divided vector reflects the overlapping of the figures, and is divided at a position where the boundary of the figure intersects with the boundary of another figure.

The vector data obtained by the above processing is converted by the output processing unit 45 into a printable raster pixel format. In order to obtain output data in pixel format, an intersection between a certain scanning line and a vector that intersects with each other is obtained, and the area from one intersection to the next intersection may be filled with an appropriate color indicated by the color attribute of the graphic.

An example in which the above procedure is applied to a specific graphic description will be described. FIG. 9 is a diagram showing a drawing figure and a corresponding page description language input and figure description. FIG. 9A
Represents a triangular figure 60 to be drawn, a page description language input 61 representing the figure 60, and a page description language input 6
FIG. 9B shows a fan-shaped graphic 70 to be drawn, a page description language input 71 representing the graphic 70, and a graphic description 62 generated from the page description language input 71. The figure description 72 is shown.

That is, the instructions 60 and 7
When page description language inputs 61 and 71 representing 0 are given, the instruction analysis unit 41 generates graphic descriptions 62 and 72, respectively. At this time, the respective graphic descriptions 62, 7
2, an identifier not uniquely included in the page description language inputs 61 and 71, that is, an identifier for uniquely specifying a figure and an overlap priority indicating an overlap priority are added. According to the illustrated example, an identifier id <1> given in the order of input and an overlap priority priority <1> also given in the order of input are added to the graphic description 62, and an identifier id is given to the graphic description 72. id <2> and overlap priority priority <2> are newly added.

The graphic descriptions 62 and 72 thus generated are sent to the page buffer 44 in order. When registering a new graphic description, the page buffer 44 checks whether the drawing area of the graphic represented by the graphic description overlaps the drawing area of the graphic represented by the already registered graphic description. Is subjected to a process of adding overlap information to the graphic description under the overlap.

When the graphic description 62 is registered in the page buffer 44 and then the graphic description 72 is registered, an overlap determination is performed. This overlap determination is performed using the circumscribed rectangle of the figure shown in FIG. In this example, since the figure 70 overlaps the figure 60, the overlap is detected by the overlap determination. When the overlap is detected, the overlapping of the element graphic descriptions included in each graphic description is checked, and intersection information is added to the element graphic description of the graphic description having a lower overlapping priority. This is shown in FIG.

FIG. 10 is an explanatory diagram of processing for adding intersection information at the time of detection of overlap. FIG. 10A shows figures 60 and 7.
0 indicates an overlapping state. The figure 60 is composed of three element figures 60a, 60b and 60c, and the figure 70 is composed of element figures 70a, 70b and 70c. The curved element figure 70a is represented by both end points and two control points. The intersection where the element figures of the two figures 60 and 70 overlap is represented by four small circles. FIG. 10B shows a graphic description to which overlap information is added. According to the illustrated example, when an overlap is detected, each element graphic description included in the graphic description 72 is checked for overlap with an element graphic represented by the element graphic description included in the graphic description 62, and the overlap priority is given. The intersection information is added to the element graphic description of the graphic description 62 having a low degree,
2a. That is, the intersection information (2, 2, 250, 300) and (2, 3, 30
0, 300) are the intersection information (2, 3, 300, 200) and (2, 1, 250,
150) is added. The intersection information includes a graphic identifier for specifying an element graphic overlapping with the element graphic, an appearance order of the element graphic description in the graphic description, and coordinates of the intersection in this order. For example, the intersection information (2, 2, 250, 300) has an identifier id = 2
Of the figure at the position of (250, 300).

FIG. 11 is a diagram showing an overlap detection state when a new graphic is added, and FIG. 12 is an explanatory diagram of processing for adding intersection information to the graphic description to optimize the graphic description. FIG. 11 shows a state in which a figure 70 is superimposed on a figure 60 and a parallelogram 80 is additionally drawn so as to partially overlap the figures 60 and 70. ing. As a result of the overlap detection, small circles representing intersection information are added to the positions of the element graphics that overlap each other.

FIG. 12 shows a graphic description corresponding to each graphic in the overlapping state in FIG. According to the graphic description 62b of the graphic 60, newer intersection information than the graphic description 62a shown in FIG. 10 is added. That is, 2
The intersection information (3, 1, 225, 30
0) and (3,3,275,300) are the intersection information (3,3,337.5,237.
5) and (3,1,312.5,212.5) are added. In the graphic description 72a of the graphic 70, new intersection information is added to the element graphic description of the two straight line segments. That is, the intersection information (3, 12, 237.5, 387.5) and (3, 3,
262.5, 312.5) include intersection information (3, 3, 300, 250) and (3, 1,
300, 225). FIG. 12 shows a graphic description 82 corresponding to the graphic 80.

As described above, the intersection information added to the graphic description is accumulated, and when an instruction indicating the end of the page is detected, next, the overlap description is optimized. In this example, the graphic description 62b is optimized and becomes a graphic description 62c. According to the graphic description 62c, the intersection information (2, 2, 250, 300) in the second element graphic description is deleted compared to the graphic description 62b. That is, of the intersections appearing on the second side of the figure 60, the intersection with the second side of the figure 70 is the intersection of the first side of the figure 80, which overlaps with the figure 70 and has a higher priority, and the third side of the figure 80. Are optimized and removed by the graphic description updating unit 42.

Next, the optimized graphic description is passed to the quantization unit 43 to generate vector data. FIG. 1 shows a state in which vector data is generated from this graphic description.
3 is shown.

FIG. 13 is a diagram showing the state of generation of vector data in the quantization unit. When vectorizing the optimized graphic description, the quantization unit 43 generates vector data while referring to the intersection information, since the intersection information is added after the element graphic description. When creating vector data for a straight line of an element graphic, the direction of the vector is indicated by the information of the start point and end point of the element graphic description, but the length is up to the intersection on the element graphic. For example, the element graphic 60b on the second side of the graphic 60
When the vector data is created, the basic direction of the vector is indicated by the description of the start point and the end point.
5, 300), the vector is generated only up to the intersection, and as a result, the vector data 60b-
1 is generated. On the other hand, the curve of an element graphic such as the first side of the graphic 70 is approximated by a series of minute straight lines. Next, the boundary of the figure to be actually drawn is determined using the intersection information. For example, the third side of the graphic 60 is divided into three parts, and shares a boundary with the graphic 70 and the graphic 80 at the division positions.

The vector data thus obtained is passed to the output processing unit 45, where the output processing is performed. The output processing will be described below. FIG. 14 is a diagram illustrating rasterization of vector data in the output processing unit. When the output processing unit 45 creates printable output data from vector data, scanning is performed sequentially from the top of the page as shown in FIG. 14 to find a vector that intersects the scanning line. Judgment is made on the boundary of the figure and the point at which the color changes, and painting is performed up to the next intersection according to the color attribute of the figure. By performing this operation for all the scanning lines constituting a page, printable output data for one page is generated. However, since the output processing unit does not perform the overlap processing, it is not necessary to simultaneously hold the output data for one page in the memory and perform the overlap processing on the memory. In addition, since it is not necessary to consider the order of inputs, vector data can be divided and processed in parallel.

Next, an embodiment in which the second embodiment of the present invention is applied to a printing system connected to a network will be described as an example. FIG. 15 is a diagram showing a configuration example of a network printing system to which the image forming apparatus according to the present invention is applied. The network printing system includes a plurality of client computers 101, 102, 103,..., A network 110, a print server 120, and a print engine 130. The image forming apparatus according to the present invention is a part of the print server 120. Has been applied as The print server 120 includes an instruction analysis unit 121, a quantization unit 122, a graphic description update unit 123, a page buffer 124, and an output processing unit 1 connected to the network 110.
25 are interconnected by a shared bus 126. The print server 120 also stores the page buffer 1
24 and an evacuation unit 127 connected to the output processing unit 125
And a printer interface 128 connected to the output processing unit 125. The output of the printer interface 128 is connected to the print engine 130.

Client computers 101, 102, 10
The print job created in 3,.
0 to the command analysis unit 121 of the print server 120. The command analysis unit 121 interprets and executes the content of the received print job as a command sequence in a page description language,
Generate a graphic description that represents each drawing graphic. The generated graphic description is sent to the quantization unit 122 and vectorized.
The vector data output from the quantization unit 122 is sent to the page buffer 124 and stored. At this time, if there is an overlap between the graphic already stored in the page buffer 124 and the newly generated graphic, the graphic description updating unit 123 updates the vector data based on the priority of the overlap. . When the instruction indicating the end of the page is detected, the vector data stored in the page buffer 124 is sent to the output processing unit 125 to generate output data in a printable format. Output data output from the output processing unit 125 is sent to the print engine 130 via the printer interface 128 and printed.

The command analysis unit 121 sequentially interprets and executes a command sequence of a page description language given as an input, and generates a graphic description. The graphic description generated by the instruction analysis unit 121 is vectorized by the quantization unit 122. This consists of a process of approximating a curve with minute line segments, the details of which are as described above.

The vector data generated by the quantization unit 122 is stored in the page buffer 124 in order.
For example, when newly registering the first vector data in the page buffer 124, if the graphic represented by the first vector data overlaps with the graphic represented by the second registered vector data, the graphic Description update unit 123
Thus, the overlap information is added to the description having a low overlap priority between the vector data. Although the flow of this processing is the same as that of the first embodiment, finding the coordinates of the intersection of vectors is a problem of finding the intersection of straight lines and can be easily solved.

The above operation is repeated until an instruction indicating the end of the page is detected, and the vector data for one page is generated in the page buffer 124. Then, the overlap information included in the vector data stored in the page buffer 124 is obtained. Perform optimization. This is a process consisting of two operations on the intersection information. First, the intersection description added to each element vector description is aligned using the coordinate values of the intersection. The arrangement method is the same as that of the first embodiment.

Next, the intersection information under the overlap with another figure is checked and deleted. Details of this processing are the same as in the first embodiment of the present invention. The vector data obtained by the above processing is converted into an output format by the output processing unit 125. The output processing unit 125 performs one of a process of generating printable image data and a process of saving vector data processed so far in the save unit 127. The device for realizing the evacuation unit may be a main storage composed of a memory or a secondary storage such as a disk.

The vector data saved by the saving unit 127 is read into the page buffer 124, and can be reused by performing an overlapping process with vector data generated thereafter.

An example in which the above procedure is applied to a specific graphic description will be described. For example, when page description language inputs 61 and 71 representing the respective figures shown in FIGS. 9A and 9B are given, figure descriptions 62 and 72 are generated by the instruction analyzer 121, respectively. At this time, to each of the graphic descriptions 62 and 72, an overlap priority indicating an overlap priority and an identifier for uniquely specifying the graphic is added. The graphic descriptions 62 and 72 generated in this way are sequentially sent to the quantization unit 122, where vector data is generated.

FIG. 16 is a diagram showing a drawing figure of a vectorized image and corresponding vector data. FIG. 16A shows a triangular figure 60 to be drawn and this figure 60
FIG. 16B shows a fan-shaped figure 70 to be drawn and a page description language input 71 representing this figure 70. And vector data 73.

As shown in the figure, in the quantization unit 122, the straight line component of the element graphic is vectorized as it is, and the curve component such as the first side of the graphic 70 is approximated by a series of minute straight lines. Then, the vector data output from the quantization unit 122 is sent to the page buffer 124 next.

FIG. 17 is an explanatory diagram of a process for adding intersection information at the time of detection of overlap. FIG. 17A shows figures 60 and 7.
FIG. 17B shows vector data 63a of the figure 60 to which overlap information is added. When registering new vector data, the page buffer 124 checks whether the drawing area of the graphic represented by the vector data overlaps the drawing area of the graphic represented by the already registered vector data. Adds overlap information to the vector data under the overlap. When the vector data 63 is registered and then the vector data 73 is registered, an overlap determination is performed and the overlap is detected. Then, each element vector included in the vector data 63 is checked for an overlap with an element figure represented by the element vector included in the vector data 73, and intersection information is added to the element vector of the vector data having a low overlap priority. The intersection information includes an identifier of a graphic for specifying an element vector overlapping with the element vector, an appearance order of the element vector in vector data, and coordinates of the intersection. In this way, when the intersection information is added to the vector data 63, the vector data 63 becomes the illustrated vector data 63a.

Next, a case where a third figure is added will be described. This new graphic is represented by the graphic description 82 shown in FIG. FIG. 18 is a diagram showing an overlap detection state when a new figure is added, and FIG. 19 is an explanatory diagram of a process of adding intersection information to vector data to optimize it. FIG. 18 shows a state in which a figure 70 is superimposed on a figure 60 and a parallelogram 80 is additionally drawn so as to partially overlap the figures 60 and 70. ing. As a result of the overlap detection, small circles representing intersection information are added to the positions of the element vectors overlapping each other.

FIG. 19 shows a graphic description corresponding to each graphic in the overlapping state in FIG. Vector data 63
a is vector data 63b, vector data 73 is vector data 73a, and vector data 83 of FIG. 80 is shown. Here, when an instruction indicating the end of the page is detected, the overlap description is optimized. Of the intersections appearing on the second side of the graphic 60, the intersection with the thirteenth side of the graphic 70 is the intersection between the intersection of the first side of the graphic 80 which overlaps with the graphic 70 and has a higher priority and the third side of the graphic 80. It is sandwiched between the intersections and is removed by the optimization unit.
As a result, the vector description of FIG.
Optimized as in 3c.

The vector data thus optimized is passed to the output processing unit 125, where the output processing is performed. When the output processing unit 125 creates printable output data, the output data is rasterized and printable output data is generated in the same manner as in the first embodiment of the present invention.

The output processing unit 125 saves the vector data in the saving unit 127, and stores it in the page buffer 124.
Is used as an initial value, and reuse of page data in overlay processing or the like can be realized with a small memory.

Although the embodiment of the second invention has been described in detail above, in the configuration illustrated in FIG. 15, overlap detection and optimization at the graphic description level by the graphic description updating unit 123 are performed first, and the quantum By performing the vectorization in the conversion unit 122 immediately before the rasterization by the output processing unit 125, it is possible to provide an embodiment of the first invention capable of performing overlay processing.

[0070]

As described above, in the first invention, the overlapping relationship between the graphic description holding means for holding the drawing graphic description generated by the drawing graphic description generating means and the drawing graphic description held by the graphic description holding means is provided. And a description updating means for updating the drawing graphic description so as to add overlapping information to the drawing graphic description based on the information. Thus, the overlap processing is performed not at the level of the image data but at a higher level of abstraction, that is, at a level with a smaller amount of data, so that the memory usage can be suppressed.

In the second invention, the vector description holding means for holding the vector description generated by the vector description generating means and the vector description based on the overlapping relationship of the vector description held by the vector description holding means. Description updating means for updating a vector description so as to add information. Thus, the overlap processing is performed not at the level of the image data but at a level of a higher level of abstraction, that is, at the level of a smaller data amount, so that the memory usage can be suppressed.

Further, even in the case of overlay processing or the like, since the overlapping processing is performed at a higher level of abstraction than the image data, it is possible to suppress the memory usage of the printer system and the data transfer load.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle configuration of the first invention.

FIG. 2 is a diagram showing a principle configuration of the second invention.

FIG. 3 is a diagram illustrating a configuration example of a network printing system to which an image forming apparatus according to the present invention is applied.

FIG. 4 is a flowchart illustrating a flow of an overlap determination procedure.

FIG. 5 is a flowchart showing a flow of processing for adding overlap information.

FIG. 6 is a flowchart illustrating an example of the flow of an alignment process.

FIG. 7 is a flowchart illustrating a flow of an optimization process.

FIG. 8 is a flowchart showing the flow of another optimization process.

FIG. 9 is a diagram showing a drawing figure and a corresponding page description language input and figure description.

FIG. 10 is an explanatory diagram of a process of adding intersection information at the time of detection of overlap.

FIG. 11 is a diagram illustrating an overlap detection state when a new graphic is added.

FIG. 12 is an explanatory diagram of a process of optimizing by adding intersection information to a graphic description.

FIG. 13 is a diagram illustrating a generation state of vector data in a quantization unit.

FIG. 14 is a diagram illustrating rasterization of vector data in an output processing unit.

FIG. 15 is a diagram illustrating a configuration example of a network printing system to which the image forming apparatus according to the present invention is applied.

FIG. 16 is a diagram showing a drawing figure of a vectorized image and corresponding vector data.

FIG. 17 is an explanatory diagram of a process of adding intersection information at the time of detection of overlap.

FIG. 18 is a diagram illustrating an overlap detection state when a new graphic is added.

FIG. 19 is an explanatory diagram of a process of adding intersection information to vector data for optimization.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drawing figure description generating means 2 graphic description holding means 3 description updating means 4 vector description generating means 5 output processing means 6 secondary storage means 11 drawing graphic description generating means 12 vector description generating means 13 vector description holding means 14 description updating means 15 Output processing means 16 Secondary storage means

Claims (14)

[Claims] 1. An image forming apparatus for obtaining an output image by executing an image drawing command described in a page description language, wherein a directed straight line representing an outline of a drawing figure by interpreting the input image drawing command. And a directed curve, a drawing graphic identifier, and a drawing graphic description generating means for generating a drawing graphic description including an overlap priority, and a graphic description for holding the drawing graphic description generated by the drawing graphic description generating means Holding means, description updating means for updating the drawing graphic description so as to add overlapping information to the drawing graphic description based on the overlapping relationship of the drawing graphic descriptions held by the graphic description holding means, Vector description generating means for generating a vector description from the held drawing graphic description, and printing using the vector description generated by the vector description generating means An image forming apparatus characterized by comprising an output processing means for generating output data capacity format, the. 2. The description updating means forms, in a description of a directed straight line or directed curve constituting a drawn figure, another drawn figure description intersecting the directed straight line or directed curve. 2. The image forming apparatus according to claim 1, wherein an identifier for specifying a directed straight line or a directed curve and a coordinate of an intersection are added as overlap information. 3. The description updating means aligns intersections appearing in descriptions of a directed straight line and a directed curved line constituting a drawing graphic description in accordance with the directions of the directed straight line and the directed curved line. Among the intersections with the figure with a higher overlap priority, and omitting the intersection with the figure with a lower overlap priority than that figure to optimize the overlap information. The image forming apparatus according to claim 2, wherein: 4. A drawing graphic description held in said graphic description holding means is saved as a template, and when another image drawing command is input, the saved drawing graphic description is read by said graphic description holding means and read. 2. The image forming apparatus according to claim 1, further comprising a secondary storage unit that becomes an initial value of a description updating operation by the description updating unit. 5. An image forming apparatus for executing an image drawing command described in a page description language to obtain an output image, wherein a directed straight line representing an outline of a drawing figure by interpreting the input image drawing command. Drawing figure description generating means for generating a drawing figure description including a sequence of segments and directed curves, a drawing figure identifier, and an overlap priority; and generating a vector description from the drawing figure description generated by the drawing figure description generating means. A vector description generating unit, a vector description holding unit for holding the vector description generated by the vector description generating unit, and adding overlap information to the vector description based on an overlapping relationship between the vector descriptions held by the vector description holding unit. Description updating means for updating the vector description so as to perform the processing, and the vector description held by the vector description holding means. It is and an output processing means for generating output data printable format using an image forming apparatus according to claim. 6. The description updating means adds an identifier specifying another element vector that intersects the element vector and coordinates of the intersection as overlap information to the description of the element vector constituting the drawing graphic vector. 6. The image forming apparatus according to claim 5, wherein the image forming apparatus is configured. 7. The description updating means arranges intersections appearing in the description of the element vectors constituting the drawing graphic vector in accordance with the direction of the element vector, and sets the intersection of the intersection with the graphic having a higher overlapping priority among the aligned intersections. 7. The image forming apparatus according to claim 6, wherein the overlap information is optimized by deleting an intersection with a graphic which is inside and has a lower overlapping priority than the graphic. 8. The vector description held by the vector description holding unit is saved as a template, and when a vector description is given by another image drawing command, the saved vector description is read into the vector description holding unit. 6. The image forming apparatus according to claim 5, further comprising a secondary storage unit that updates the description by the description updating unit with respect to the given vector description. 9. An image forming method for obtaining an output image by executing an image drawing command described in a page description language, wherein a directed straight line representing an outline of a drawing figure by interpreting the input image drawing command And a directed graphic curve sequence, a drawing figure identifier, and an overlapping priority are generated. At the level of the generated drawing figure description, an overlapping process is performed based on the overlapping relationship of the drawing figure descriptions. Generating a vector description from the superimposed drawing figure description, and generating output data in a printable format from the generated vector description. 10. The step of performing the superimposing process includes the steps of: describing a directed straight line component or a directed curved line constituting a drawn graphic; The image forming method according to claim 9, further comprising a step of adding an identifier for specifying a directed straight line component or a directed curved line component constituting the description and coordinates of the intersection. 11. The step of performing the superimposing process includes arranging the intersections appearing in the description of the directed straight line component and the directed curved line component constituting the drawing graphic description according to the directions of the directed straight line component and the directed curved line component. 11. The method according to claim 10, further comprising the step of deleting, from among the arranged intersections, intersections with a graphic having a lower overlapping priority than the graphic, which is inside the intersection with the graphic having a higher overlapping priority. The image forming method as described in the above. 12. An image forming method for obtaining an output image by executing an image drawing command described in a page description language, wherein a directed straight line representing an outline of a drawing figure by interpreting the input image drawing command. A drawing description consisting of a sequence of drawing segments and directed curves, a drawing figure identifier, and an overlap priority, generating a vector description from the generated drawing figure description, and generating a vector description at the level of the generated vector description. Performing an overlapping process based on the overlapping relationship and generating printable output data from the overlapped vector description. 13. The step of performing the superimposition process includes the step of adding an identifier specifying another element vector intersecting the element vector and the coordinates of the intersection to the description of the element vector forming the drawing graphic vector. 13. The image forming method according to claim 12, comprising: 14. The step of performing the superimposing process comprises: aligning intersections appearing in the description of the element vectors constituting the drawing graphic vector in accordance with the direction of the element vector;
14. The method according to claim 13, further comprising the step of deleting an intersection with a graphic having a lower overlapping priority than the graphic that is inside the intersection with the graphic having a higher overlapping priority among the aligned intersections. Image forming method.