JPH05120442A - Vector picture processor - Google Patents

Abstract

PURPOSE:To provide a vector picture processor capable of holding the precision of pixel density while minimizing the deterioration of a processing speed. CONSTITUTION:The vector picture processor is applied for a picture outputting device. The picture outputting device inputs vector pictures, and extends them to a multilevel memory, and outputs them to a multilevel outputting device. The vector picture processor operates the extraction of an edge part based on picture data by an previous processing and extracting means alpha (S108). The number of vectors constituting the extracted edge part is decided by a vector number deciding means beta (S200). A switching means epsilon operates a switching to the first edge part processing means gamma (S201; N), or operates the switching to the second edge part processing means delta (S201; Y), according to the decided number of vectors. The first edge part processing means gamma operates a normal edge processing (S202, S203), and the second edge part processing means deltaoperates the edge processing of the plural vectors (S204, S205).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector image processing apparatus that can be used in image devices such as page printers, facsimile machines, and image input apparatuses. The present invention relates to a vector image processing device that shortens image processing time while maintaining accuracy.

[0002]

2. Description of the Related Art As a vector image processing apparatus of this type, there is, for example, one that employs an anti-aliasing processing system (Japanese Patent Laid-Open No. 2-115480). With this vector image processing device, with respect to the input vector image,
In the figure edge portion, anti-aliasing processing is executed in which the pixel density in the unit figure is determined according to the area ratio of the unit figure that is applied to the pixels of the edge portion. In the above vector image processing device,
By executing the anti-aliasing process, the density of the graphic edge portion is modulated as compared with the inside of the graphic, and it is possible to obtain a visually smooth and high-quality output.

[0003]

In the above-described vector image processing apparatus, it is necessary to obtain the area ratio for all images, so that there is an inconvenience that it takes processing time to determine the pixel density. Therefore, it has been proposed to adopt an edge filtering process capable of extracting only the graphic edge portion and execute the anti-aliasing processing only for the edge portion. By adopting this edge filtering process, the processing time for determining the pixel density described above can be shortened. However, even in this edge filtering process, when the start point and the end point of the vector are to be expressed in real numbers (pixel units), the edge part determination process must be complicated in order to maintain the pixel density accuracy. Therefore, there is a drawback that the processing speed becomes slow. SUMMARY OF THE INVENTION The present invention is intended to improve the above-mentioned drawbacks, and an object of the present invention is to provide a vector image processing apparatus that attempts to maintain the accuracy of pixel density while minimizing a decrease in processing speed.

[0004]

In order to achieve the above object, a vector image processing apparatus of the present invention inputs an image composed of a vector, expands the image in a multivalued memory,
In an image output device capable of outputting the multi-valued data to a multi-valued output device, preprocessing / extracting means for capturing and registering the image on each scan line and extracting an edge portion based on the registered data, For the edge portion extracted by the pre-processing / extracting means, the pre-processing / extracting is performed according to the number-of-vectors determining means for determining the number of vectors forming the edge portion, and the number of vectors determined by the vector-number determining means. Switching for switching the edge portion extracted by the means to the first edge portion processing means for processing by the normal edge portion processing or the second edge portion processing means capable of edge processing for a plurality of vectors And means. Here, it is preferable that the above-described vector number determining means has a configuration in which a flag indicating the directionality is added to the vector and the number of vectors is determined by the number of the vectors having the same direction successively appearing in the scan line direction. .. Further, the above-mentioned second edge processing means takes out those whose start point / end point coordinates of the vector are within the same scan line, and defines the coordinates of the upper and lower intersection points of the scan line by the start point / end point inside thereof. The edge portion range may be determined based on the maximum value and the minimum value of.

[0005]

According to the present invention, the number of vectors forming the edge portion is calculated, and when the number is one kind of vector, the edge processing is executed in a short time by the first edge processing means for executing simple processing. , If the number is a vector of a plurality of types, the edge processing is performed by the second edge processing means capable of performing an edge processing in a relatively short time while maintaining a predetermined processing accuracy even in the case of a plurality of types. Therefore, the accuracy of determining the edge portion range is good, and the processing speed of determining the edge portion range can be relatively fast. In addition, the second edge processing means uses the start point and the end point of the vector in the same scan line as the coordinates at which these vectors intersect at the top and bottom of the scan line, and determines the maximum value of the coordinates.
Since the edge part range is determined based on the minimum value, useless discrimination for range detection can be omitted.

[0006]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing an image system including a printer controller to which an embodiment of the vector image processing apparatus of the present invention is applied. In FIG. 1, the host computer 1 creates various document images according to an existing application or the like. The document image processed by the present invention is a vector image such as characters and line drawings described in PDL language (Page Description Language) represented by Postscript. The vector images such as characters and line images sent from the host computer 1 are received page by page by a general-purpose communication device in the printer controller 3 as an image output device. The printer controller 3 expands the data received for each page into multi-valued image data and stores it in the internal page memory. When the printer controller 3 completes the processing for one page, it becomes possible to send the image data in the memory to the page printer 5. The page printer 5 receives the image data in the memory of the printer controller 3 and prints it out.

FIG. 2 is a block diagram showing in detail the internal configuration of a printer controller which is an example of the above-mentioned image output device. The vector image processing apparatus of the present invention is realized inside the printer controller 3. In FIG. 2, the printer controller 3 includes a central processing unit (CPU) 31, a ROM 32, a RAM 33, and a receiving device 3.
4, the page memory 35, the CPU 31 through the internal bus 36, the ROM 32, the RAM 33, the receiving device 3
4, connected to page memory 35. Data for each page from the host computer 1 is stored in the CPU 3
1 through the receiving device 34 and the internal bus 36 under the control of RA
It is stored in M33. The data stored in the RAM 33 is stored according to the program stored in the ROM 32.
It is developed by the CPU 31 and written in the page memory 35. At this time, the CPU 31 executes the processing according to the processing procedure of the present invention stored in the ROM 32, whereby the vector image processing apparatus of the present invention is realized.

This vector image processing apparatus is a receiving apparatus 3
Preprocessing to extract the edge part from the received data from 4
For the extraction means α and the edge portion extracted by the preprocessing / extraction means α, the number of vectors determining means β for determining the number of vectors forming the edge portion, and the number of vectors determined by the vector number determining means β Depending on the above,
A first edge portion processing means γ that processes the edge portion extracted by the extraction means α by a normal edge portion processing, or a second edge portion processing means that can edge-process the extracted edge portion for a plurality of vectors. It is composed of switching means ε for switching to δ. Also, the page memory 35
Image data written to the page printer 5
Is output to.

Next, the operation of the above-described embodiment will be described based on FIGS. 1 and 2 and with reference to FIGS. First, a general description of an image processing operation including anti-aliasing processing will be given with reference to FIGS. 3 to 7, and then an operation for eliminating inconveniences in the image processing operation according to FIGS. 3 to 7 will be described. 8 to 10, and FIGS. 6 and 7 will be described.

<General Description of Image Processing Operation> FIG. 3 is a flow chart of an image improvement processing procedure executed by the CPU in the printer controller, for a figure whose starting point and ending point are integer coordinate type vectors. It is explanatory drawing of the general flow of the anti-aliasing process using edge filtering. FIG. 4 is a process explanatory diagram of the edge portion processed when the flowchart of FIG. 3 is executed. 5A and 5B are explanatory diagrams of the anti-aliasing processing. FIG. 5A is an explanatory diagram of the processing, and FIG.
(B) is an explanatory view of the processing result. FIG. 6 is an explanatory diagram of an image processed according to the embodiment of the present invention. Figure 7
It is explanatory drawing of the error which arises in the process by FIG. First,
The anti-aliasing processing used in this embodiment will be described. This processing is that raster conversion is performed depending on the resolution of the output device by thinly density-modulating the edge portion of the graphic when raster-converting the vector graphic. The jaggy that sometimes occurs is visually removed, and high quality output is obtained. Since this anti-aliasing processing should be performed on the graphic edge portion, the processing speed can be increased by limiting the processing target range to the graphic edge portion in advance. This is called edge filtering.

In the host computer 1, PDL
Vector graphic data described in a language or the like is received by the printer controller 3 (step 10 in FIG. 3).
0). In the printer controller 3, when the data of the data received by the receiving device 34 under the control of the CPU 31 is determined by the CPU 31 to be a curve vector (step 101; Y), CP
The vector is approximated by a straight line vector by U31 (step 102), and the line table (RAM3
3) is registered (step 103). On the other hand, when the CPU 31 determines that the vector of the image is a straight line vector (step 101; N), it is directly registered in the line table (step 103). These processes (steps 100 to 103) are performed until, for example, one page of image data is completed (step S104;
N), repeat.

When the input of the vector graphic data from the host computer 1 is completed (step 10
0; Y), the CPU 31 changes the registered straight line vector to
Sorting is performed according to the y coordinate of the starting point (step 105). Next, in the scan line processing, the CPU 31 collects the vector whose y-coordinate of the starting point has the same value as the y-coordinate of the scan line to be processed, and AET
It is registered in the (active edge table) (step 107). The CPU 31 determines the vector registered in the AET corresponding to the y coordinate of the scan line in this way.
First, the x coordinate of the starting point is sorted (step 107). After that, the CPU 31 determines and takes out the left edge portion of the figure composed of one or a plurality of vectors in order from the one having the smaller x coordinate (step 108). Next, the CPU 31 determines, for one edge, the range covered by the edge (step 10).
9). The anti-aliasing process is performed on the edge portion thus determined by the CPU 31 (step 110).

When this processing (step 110) is completed, the CPU 31 determines whether the processing of both the left and right edge portions has been completed (step 111), and if not completed (step 111; N), a pair is formed. The same processing as above is performed on the right edge portion of the other figure (steps 108 to 110). After the processing is completed for both edges (step 111; Y), all the pixels inside the figure sandwiched between both edge ranges are set to a constant density (step 112). When this process ends, the CPU
31 first updates the y coordinate (step S113), and then determines whether all image processing has been completed (step 1
14), if not completed (step 114; N),
The image processing is executed again (steps 106 to 113).

By the way, in the edge area range determination processing (step 109), when the graphic edge portion is composed of one type (the same direction) of vector, the inclination of the vector does not change in the scan line. Therefore, the range of the edge portion is obtained by using the inclination. That is, as shown in FIG. 4, when the starting coordinate is (x ₁ , y ₁ ) on the AET of the coordinate y = y ₁ of a certain vector V, the coordinate at y = y ₁ +1 is (x ₁ + dx / Dy, y ₁ +1), so x
_{From the} pixel represented by the integer value obtained by cutting off ₁ to the pixel represented by the integer value obtained by cutting off (x ₁ + dx / dy) is calculated as the edge range.

Next, as the anti-aliasing processing in step 110 of FIG. 3, the sub-pixel division method is used in this embodiment. The sub-pixel division method is one of the density modulation methods, and as shown in FIG.
One pixel is virtually n × m (in the embodiment, n = 4, m
= 4) sub-pixels. The sub-scan line SSL can scan sub-pixels in the m direction, and the m-line sub-scan line SSL constitutes one scan line ScL. Also, the above 1
For each pixel, the area ratio, which is the ratio of the image (vector V) on the pixel, is approximately calculated by counting the number of sub-pixels on which the image is applied (see FIG. 5B). For example, in FIG. 5B, [5/16], [16/16], [1],
[1], [15/16], and [3/16] are determined. According to the area ratio thus obtained, the maximum density is obtained when the area ratio is [1], and the area ratio is

The modulation density is determined so that the density becomes 0 when [0].

<Inconvenient point of edge range determination processing in the above description> However, in the above-mentioned anti-aliasing processing, when the start point / end point information of a vector is given in real multiples in pixel units, that processing is performed. The result can be erroneous. For example, in FIG.
As shown in (b), the nature (inclination, direction) of vectors V ₁ and V ₂ that form one edge at the y coordinate in the middle of a scan line having a width of y = 1 to y = 3. A large error is generated in the case of a large change. That is, the vector V in the range of y = 1 to y = 2 in FIG.
₂ greatly changes the nature of the vector, but when the edge range determination process (step 107) of FIG. 3 is performed on this vector V ₂ by the method described in FIG. 4, it becomes as shown in FIG. Further, the edge range is EA. However, the actual range of the vector V ₂ is the range E _E A as shown in FIG. 7, and the error N has occurred.

In order to reduce such an error, a method of adding various judgments can be considered, but the edge range determination processing becomes complicated, and if this method is applied to all edges, the judgment processing time will be increased. It will cost you.
Therefore, in the embodiment of the present invention, in order to perform the edge determination for each scan line more accurately and in a processing time as short as possible, a vector forming the target edge between one scan line is used. Is changed, that is, whether the edge is composed of a plurality of vectors, the subsequent edge part range determination processing is switched.

<Changes> Specifically, according to the present invention, firstly, in the case where an edge is composed of one vector and the property of the vector at the edge portion does not change, A simple edge range determination process that does not require processing time is used. Secondly, when the edge is composed of multiple vectors and the nature of the edge vector changes between scan lines, Although it takes some time, the edge range determination process including some determination processes that reduce the edge determination error is used. By performing such processing, the vector image processing apparatus of the present invention shortens the processing time and also improves the processing accuracy.

FIG. 8 shows the processing steps 109 to 11 of FIG.
It is a flowchart which changes 0 and is for demonstrating the switching operation of edge part range determination processing. FIG. 9 is a flowchart for explaining the edge part constituent vector number determination process in detail. FIG. 10 is a flowchart for explaining in detail the edge part range determination processing in consideration of a plurality of vectors. In FIG. 8, the CPU 31 of the printer controller 3 first realizes the vector number determination means β. The vector number determining means β is a preprocessing / extracting means α.
As a result of the execution (step 108), the number of vectors of the extracted edge portion is determined (step 80).
0). This processing eliminates the following inconveniences.
In general, when the y-coordinates of the vector start point / end point are represented by a numerical value smaller than the minimum unit of y, there are cases where a plurality of vectors exist in a line having the minimum unit width to form an edge, At this time, inconvenience arises if the left and right edges of the line are paired with two edges each.
Therefore, in this determination process, a flag indicating directionality is introduced to the vector, the periphery of the figure is represented by a set of vectors around a certain direction, and at the intersection of the scan line and those vectors, the left and right edges are also referred to with reference to the vector flag It has established. For example, if the downward vector indicates the left edge and the upward vector indicates the right edge,
Even if several vectors with the same direction appear in succession, they all have the same edge. On the minimum unit width line, in the case of the left edge, the edge is represented by the leftmost vector of these vectors, and in the case of the right edge, the edge is represented by the rightmost vector of these vectors. I will.

According to the present invention, the processing by the vector number determining means β is performed (step 200), instead of the sub-scan line which is the minimum line unit of the sub-pixel dividing method.
It is applied to each scan line to determine the number of edge constituent vectors. Now, details of the processing by the vector number determining means β will be described with reference to FIG. 9. First, by the integer value of the y coordinate of each vector, C
The PU 31 registers a vector in AET0 for each subline (step 300). As a result, for example, FIG.
In the case of the scan line ScL ₁ of the figure in (b), AET
Four vectors are registered in 0. After that, CPU31
Sorts the vector in AET0 by its x coordinate (step 301). Then, CPU3
In order to extract the vectors forming the left and right edges of the figure, the counter 1 is set to reset (= 1) (step 302), and the direction flags of the vectors existing in the AETO are sequentially examined from the left (step 303). .. CPU3
When a vector having the same direction flag appears successively (step 304; Y), 1 counts the number of edges as if they consist of these vectors (step 305). Further, when the vector having the same direction flag does not appear successively (step 304; N), the CPU 31 takes the counter value as the number of vectors constituting the edge (step 306). Next, the CPU 31 determines whether or not all the vectors in all AET0 have been referred to (step 307), and if they have not been referred to (step 307; N), shifts to the recognition operation of the number of vectors again (steps 302 to 302). 307). When all such operations are completed, in the scan line ScL ₁ of FIG.
Two right edge vectors are recognized and determined.

In this way, when the number of vectors is determined in the processing of FIG. 8 (step S200), CP
U31 realizes the switching means ε, and the switching means ε determines whether or not the edge portion is composed of a plurality of vectors (step 201). Here, the switching means ε determines that the processing result by the vector number determining means β is (step 20
0), when it is determined that the vector does not consist of a plurality of vectors (step 201; N), the normal edge range determination processing by the first edge processing means γ (processing of FIG. 3 (step 109)). Equivalent to step 2) (step 2)
02). After that, the anti-aliasing process is executed by the first edge processing unit γ achieved by the CPU 31 (step 203), and the process proceeds to the next process. On the other hand, when it is determined by the switching means ε that the vector is composed of a plurality of vectors (step 201; Y), the second edge processing means δ is switched to, and the second edge processing means δ causes a plurality of vectors. The edge range determination is performed on the edge formed by the vector (step 204).

Next, the details of the edge range determination process (step 204) for an edge composed of a plurality of vectors by the second edge processing means δ will be described with reference to FIG.
This will be described with reference to the flowchart in FIG. CPU31
The second edge portion processing means δ is realized, and the second edge portion processing means δ refers to the start point / end point coordinates of all the vectors forming the edge (step 40 in FIG. 10).
0), only those on the scan line among them, that is, only those in which the integerized y coordinate value obtained by truncating the y coordinate matches the y coordinate value indicating the scan line are extracted (step 401; Y), The coordinate values are registered (step 402). Furthermore, if the vector does not have a start point and an end point in the same scan line, the CPU
If it is determined in step 31 (step 403; N), the CPU 31 determines whether the registered coordinate is the end point or the start point (step 404). Here, if the end point (step 404;
At the end point, the CPU 31 takes out the coordinates of the point where the vector intersects the upper boundary of the scan line (step 4).
05). If the CPU 31 is the starting point (step 4)
04; start point), and the coordinates of the point where the vector intersects the lower boundary of the scan line are extracted (step 408). From the coordinates obtained as described above, the CPU 31 determines the maximum value and the minimum value of the x coordinate (step 406) and the edge portion range (step 407).

For example, FIG. 6 (b) scan line ScL
Starting point of the vector V ₁ constituting _one of the left edge - endpoint,
(5.0,0.0)-(2.3,1.4), vector V
The start point-end point of ₂ is (2.3, 1.4)-(0.5,
3.6), the start point and end point coordinates on the scan line ScL ₁ are, for example, in the case of the vector V ₁ ,
(2.3, 1.4). Further, since the vector V ₁₁ has the end point in the scan line 1, when the intersection with y = 1 is examined (3.1, 1.0), the vector V ₁₂ has the start point in the scan line ScL ₁ , and , Y = 2, the result is (1.8, 2.0). Therefore, the maximum and minimum values of the x coordinate of the above points are
Since x = 3.1 and x = 1.8, the edge range is determined by taking their cutoff values and being the pixel portion from x = 1 to x = 3. Similarly, when such a specific operation is performed on the vector V ₂ shown in FIG. 5B, the edge portion range becomes the range E _E A shown in FIG. 7, and the error N is eliminated. As described above, the detailed operation of the processing (step 204) for determining the edge portion range in consideration of a plurality of vectors is performed.

Next, when the range of the edge portion is determined as described above (step 204), the second edge portion processing means δ performs the anti-aliasing processing by the sub-pixel division method, but the edge portion has a plurality of vectors. The vector is newly registered for each sub-scan line (step 205). In the second edge processing means δ, the steps 204 and 205 are combined so that the edge range is updated for each sub-scan line and the changed sub-scan line is included in the changed range. You may use the algorithm which changes the area ratio of a part.

In this way, the second edge processing means δ
The processing by is completed, and it becomes possible to accurately determine the edge range and perform the aliasing processing in a relatively short time. As described above, in this embodiment, first, the preprocessing / extracting means α
The edge part is extracted by, and then the edge part is taken into the vector number determining means β, and this vector number determining means β
Determines the number of vectors forming the edge part (step 200), and if the switching means ε determines that the edge is composed of one vector (step 201; N), the edge part is determined. Since the property of the vector of does not change, a simple edge range determination processing is performed by the first edge processing means γ (steps 202 and 203), while the switching means ε configures an edge with a plurality of vectors. If it is determined that (step 201;
Y), the nature of the edge vector changes between scan lines (vector V _{11 in} FIG. 6B).
(V ₁₂ , V ₂ ), the edge portion range determination processing including the determination processing for reducing the edge portion determination error is executed by the second edge portion processing means δ even if the processing time is somewhat long (step 204). , 205).

That is, in this embodiment, the edge portion processing (steps 202, 203, or step 20) is performed.
4, 205), the switching is performed according to the number of constituent vectors of the edge part (step 201). Therefore, the edge part range detection is also performed in the edge filtering process (step 204) when the start point and the end point of the vector are represented by real numbers in pixel units. The unnecessary discrimination for is omitted. By performing such processing, the vector image processing apparatus of the present invention shortens the processing time and also improves the processing accuracy.

[0027]

As described above, according to the present invention, the method for processing the edge portion is switched depending on the number of constituent vectors of the edge portion, so that the edge in the case where the start point and the end point of the vector are represented by real numbers in pixel units Also in the filtering process, unnecessary discrimination for detecting the edge range is omitted, and the processing time is shortened while maintaining the accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a printing system to which an embodiment of a vector image processing device of the present invention is applied.

FIG. 2 is a block diagram showing a configuration example of a printer controller to which an embodiment of the present invention is applied.

FIG. 3 is a flowchart for explaining an overall flow of an image processing procedure which is the basis of the present invention.

4 is an explanatory diagram of calculation of an edge portion in the image processing of FIG.

FIG. 5 is an explanatory diagram of anti-aliasing processing in the image processing.

FIG. 6 is a diagram for explaining processing for obtaining an edge portion in a plurality of scan lines in the same image processing.

FIG. 7 is a diagram for explaining an error caused by calculating an edge portion of a vector in which the property of the vector changes by the image processing operation described in FIG.

FIG. 8 is a flowchart showing a main part of image processing of the present invention.

FIG. 9 is a flowchart for explaining the edge part constituent vector number determination process in the image processing of the present invention.

FIG. 10 is a flowchart for explaining edge area range determination processing in image processing of the present invention.

[Explanation of symbols]

 1 host computer 3 printer controller 5 page printer 31 CPU 32 ROM 33 RAM 34 receiver 35 page memory 36 internal bus α pre-processing / extracting means β vector number determining means γ first edge processing means δ second Edge processing means ε switching means

Claims (3)

[Claims] 1. An image output device capable of inputting an image composed of vectors, developing the image in a multi-valued memory, and outputting the multi-valued data to a multi-valued output device, wherein the image is displayed on each scan line. Pre-processing / extracting means for fetching and registering, and extracting an edge part based on the registered data, and a vector for determining the number of vectors forming the edge part for the edge part extracted by the pre-processing / extracting means A first edge portion processing means for processing the edge portion extracted by the pre-processing / extracting means by a normal edge portion processing according to the number determining means and the number of vectors determined by the vector number determining means, or Switching means for switching the extracted edge portion to a second edge portion processing means capable of edge processing for a plurality of vectors, An image processing device. 2. The vector number determining means is configured to add a flag indicating directionality to the vector and determine the number of vectors by the number of consecutively appearing vectors in the same direction in the scan line direction. The vector image processing device according to claim 1. 3. The second edge processing means extracts a vector having start and end point coordinates of a vector within the same scan line, and uses the start and end points inside thereof as coordinates for the upper and lower intersection points of the scan line. Maximum value of the coordinates
The vector image processing apparatus according to claim 1, wherein the edge range is determined based on the minimum value.