JP3567728B2 - Image processing method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus that stores character design information as outline information and corrects dropout when outputting small-sized characters.
[0002]
[Prior art]
In an output device based on a bitmap screen, such as a page printer or a display, as the pixels become finer, that is, as the resolution increases, more data is required to display characters and graphics of the same size. In particular, even for character information having a fixed contour, it is necessary to have bitmap data for each size, which is inefficient. Therefore, character information does not have bitmap data for each size but outline information. A method of displaying a character by enlarging or reducing is followed by filling the inside of the outline of the character is advantageous.
[0003]
However, when a small-size character is output (displayed) in the method of filling the inside of the outline, the interval between the outlines may be too narrow and dropout may occur in the fill. In order to avoid this dropout phenomenon, there are two methods: outline information that has outline change information at the time of small size output in the outline information itself, and method of detecting and correcting the dropout occurrence location in the processing system. There are two. The former is generally faster in processing and can correct the destruction of the character design at the data creation stage. However, when the number of characters increases, the data size increases and the time and effort required for data creation also increase. In the latter case, the data does not need to be changed, but the processing is slower, and the character design may be distorted compared to the former case. Therefore, it is now mainstream to use the former and the latter in combination.
[0004]
Since the present invention relates to the latter method among the above two methods, the latter method will be further described.
[0005]
FIG. 14 shows an outline of a character and a bit map obtained from the outline. When a character is output (displayed) as shown in the figure, a bitmap is output in which pixels inside the outline of the character to be output are inverted with respect to other pixels. Each pixel is a square having a height of 1 and a width of 1, as shown in FIG. 15, and integer coordinate values come at the four corners. The coordinates of the pixel are represented by the coordinate value of the lower left corner, which will be referred to as pixel coordinates. When the center point of a pixel is inside the contour as shown in FIG. 16, the pixel is determined to be inside the contour.
[0006]
Next, an example of scan conversion will be described. In this example, the inside and outside of the outline are determined under a condition called an EVEN-ODD rule that does not consider the direction of the outline.
[0007]
Here, a line connecting the center points of the pixels in the x-axis direction as shown in FIG. 17 is called a scanning line or a main scanning line, and a line connecting the center points of the pixels in the y-axis direction is called a sub-scanning line. . When finding the inside of the contour, as shown in FIG. 18 (a), the intersection of the contour and the scanning line is determined, and the intersection and the y coordinate are equal, and among the pixels on the right side of the intersection (the center point of the pixel) Select the closest pixel. This pixel is called an edge, and the edge can be obtained by, for example, rounding off the first decimal place of the x coordinate value of the intersection.
[0008]
Now, when the edges are selected for all the contour lines, the pixels sandwiched between the edges are inverted for each scanning line as shown in FIG. At this time, of the edges serving as the start point or the end point of the pixel to be inverted, the pixel serving as the start point is inverted, but the pixel serving as the end point is not inverted.
[0009]
Further, when edges overlap at the stage of selecting an edge, if the number of overlaps is an even number, the edges are deleted. Unless this operation is performed, the filling is not performed accurately.
Note that the same image can be obtained even if scan conversion is performed from the sub-scanning line direction unless dropout occurs.
[0010]
By the way, the simplest way to register the selected edge is to invert the pixel with the actual bitmap as shown in FIG. However, when the size of the character becomes large or at high resolution, all pixels must be examined at the filling stage, which is disadvantageous in terms of speed, and complicated painting rules are used due to the simple structure. It is disadvantageous that the memory efficiency is deteriorated if edge information such as the direction of a contour line is added.
[0011]
Therefore, there is a method of managing each scanning line in a list as shown in FIG. In this method, the selected edges are registered in a list, and when all the edges are registered, each list is sorted. In the filling process, two edges are extracted from the list, and these are set as a start point and an end point. This list is called an edge list.
[0012]
Here, FIG. 20 shows an example of the occurrence of dropout.
When two contour lines pass between the center points of adjacent pixels as shown in FIG. 20A, dropout occurs because there is no pixel to be inverted. In this case, as shown in FIG. 20B, edges selected from intersections of the two contours with the scanning line overlap. When the edges overlap, there is no problem if the space between the outlines is outside the outline, but if it is inside the outline, a dropout occurs. If the edges overlap, they are deleted as described above, and such pixels need to be registered in a bitmap or edge list different from the edges. FIG. 20C shows an example of a dropout that cannot be found from the edge obtained from the intersection between the contour and the scanning line. In this case, the dropout is selected by selecting an edge from the sub-scanning line direction. Can be found. As can be seen from this example, in order to find all the dropouts, it is necessary to execute from both the scanning line direction and the sub-scanning line direction.
[0013]
In such processing, if the size of the character is sufficiently large and no dropout occurs, the selection of the edge from the outline may be performed from either the scanning line or the sub-scanning line direction. When it is necessary to process a small dropout, edges must be selected from both directions, and the time required for output (display) processing including the processing of the dropout increases.
[0014]
Further, as a technique for preventing or suppressing the occurrence of dropout, an “outline font drawing apparatus” disclosed in JP-A-8-87602 and an “outline font drawing” disclosed in JP-A-8-95545 are disclosed. Device ", and" outline filling device "disclosed in JP-A-8-77372.
[0015]
In the "outline font drawing apparatus" described in JP-A-8-87602, scan conversion is performed in each of the scanning line direction and the sub-scanning line direction, and separate bitmaps are created. A bitmap image is obtained, and in the "outline font drawing apparatus" described in Japanese Patent Application Laid-Open No. 8-95545, scan conversion is usually performed by shifting a scan line set at the center of each pixel, thereby performing dropout. The occurrence of is suppressed.
[0016]
In the “outline filling device” described in Japanese Patent Application Laid-Open No. 8-77372, an edge is corrected with reference to coordinates of an intersection with a contour line of the immediately higher scan line.
[0017]
[Problems to be solved by the invention]
However, in the "outline font drawing apparatus" described in JP-A-8-87602, scan conversion is always performed from both the scanning line direction and the sub-scanning line direction, and the time required for dropout detection becomes longer. In addition, when scan conversion is performed on a character or a part of a character that is unlikely to cause dropout, wasteful processing is performed.
[0018]
In the “outline font drawing device” described in Japanese Patent Application Laid-Open No. 8-95545, since the occurrence of dropout is suppressed by shifting the scan line, there is a possibility that an image different from the image originally intended may be formed. Since the moving direction of the scan line is determined from the direction of the contour line, some of the rules cannot be applied depending on the rule of filling.
[0019]
Further, in the “outline filling device” described in JP-A-8-77372, only the coordinates of the intersections are used. Therefore, when the upper and lower ends of the separate contour lines have the intersections with the adjacent scan lines, respectively. In addition, there is a possibility that connection may be made by mistake, and since processing is performed in units of scan lines, branching of processing for each contour cannot be performed.
[0020]
Therefore, an object of the present invention is to provide an image processing method and apparatus capable of processing dropout detection at high speed and generating a high-quality bitmap image.
[0021]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 selects a pixel closest to the scanning direction from an intersection of a contour line of a character to be drawn and a scanning line as an edge, and inverts a pixel between edges on the scanning line. Then, in the image processing method for developing an image corresponding to the character on a bitmap, the first edge is sequentially selected on the target scanning line, and the first edge is selected on the adjacent scanning line adjacent to the target scanning line. A second edge adjacent to the first edge on the contour line among the two edges is moved on the target scanning line in a direction orthogonal to the target scanning line, and the moved position is defined as the first edge. Is set as a mark edge corresponding to the first edge and the mark edge, and a predetermined value is assigned to each of the first edge and the mark edge, and the predetermined values on the scan line of interest are sequentially added. A region between a third edge, which is one of the first edges, and a mark edge in which the correspondence between the third edge is set, and a third edge of the first edge, which is different from the third edge. An area in which the area between the fourth edge and the mark edge corresponding to the fourth edge overlaps is specified, and the overlapping area is detected as a missing pixel.
[0022]
Further, according to a second aspect of the present invention, in the first aspect of the present invention, the scan line of interest is parallel to the x axis on an xy plane represented by an x axis and a y axis orthogonal to the x axis. If the adjacent scanning line has a smaller y value than the target scanning line on the xy plane, if the inclination of the contour line is positive, -1 is assigned to the first edge and the mark edge is assigned. If the inclination of the contour line is negative, 1 is assigned to the first edge and -1 is assigned to the mark edge, and the area where the addition result is 2 is detected as the overlapping area. It is characterized by doing.
[0023]
According to a third aspect of the present invention, in the first or second aspect, the setting of the mark edge is performed when the inclination of the contour is larger than −1 and smaller than 1.
[0024]
According to a fourth aspect of the present invention, a pixel closest to the scanning direction from an intersection of a contour line of a character to be drawn and a scanning line is selected as an edge, and pixels between edges on the scanning line are inverted to correspond to the character. An image processing apparatus for developing an image to be processed on a bit map, an edge selecting means for selecting an edge on a scanning line, an edge selected on the scanning line of interest by the edge selecting means as a first edge, The edge selected by the means on an adjacent scanning line adjacent to the target scanning line is set as a second edge, and the second edge adjacent to the first edge and the contour line is set in a direction orthogonal to the target scanning line. Mark edge setting means for moving on the target scanning line and setting the moved position as a mark edge corresponding to the first edge; and the first edge and the mark edge A predetermined value is assigned to each of them, the predetermined values on the target scanning line are sequentially added, and a correspondence between the third edge, which is one of the first edges, and the third edge is determined based on the addition result. A region between the set mark edge and a region between a fourth edge of the first edge different from the third edge and a mark edge corresponding to the fourth edge overlap with each other. Pixel omission determining means for specifying an area and detecting the overlapped area as omission of pixels.
[0025]
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the scan line of interest is parallel to the x-axis on an xy plane represented by an x-axis and a y-axis orthogonal to the x-axis. If the adjacent scanning line has a smaller y value than the target scanning line on the xy plane, the pixel omission determining unit determines that the first edge has a negative value if the inclination of the contour line is positive. When 1 is assigned to the mark edge and 1 is assigned to the mark edge, and if the inclination of the contour line is negative, 1 is assigned to the first edge and -1 is assigned to the mark edge, and the addition result is 2. A region is detected as the overlapping region.
[0026]
According to a sixth aspect of the present invention, in the fourth or fifth aspect, the mark edge setting means operates when the inclination of the contour is larger than −1 and smaller than 1.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image processing method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0032]
FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to the present invention.
The image processing apparatus 10 includes a coordinate conversion unit 1 that performs coordinate conversion such as enlargement / reduction of outline information and divides a curve (contour line information) into straight lines of a size that can be seen smoothly according to pixels (approximation using a plurality of straight lines). , Select an edge from the scanning line direction and register it in the edge list, then detect the overlapping portion of the edge and register it in the dropout registration list, and find the mark edge from the registered edge and register it in the edge list Dropout detection means 2, dropout determination means 3 which determines the overlap of the area between the mark edge and the edge, finds the pixel where the dropout occurs, and registers it in the dropout registration list, and generates a bitmap from the edge list And a bitmap developing means 4 for synthesizing information of the dropout registration list.
[0033]
As shown in FIG. 2, the image processing apparatus 10 actually includes a CPU 11, a RAM 12, a ROM 13, an external storage device 14, a video I / F (interface) 15, a frame buffer 16, and a printer I / F (interface). 17 is provided.
[0034]
The coordinate conversion means 1, the intersection / dropout detection means 2, the dropout determination means 3, and the bitmap development means 4 shown in FIG. 1 are configured on the CPU 11 by a program stored in the RAM 12 or the ROM 13. The RAM 12 stores the above-described edge list and dropout registration list, and the ROM 13 and the external storage device 14 store outline font data. The frame buffer 16 temporarily stores the bitmap image developed by the bitmap developing means 4 and stores the image in a display (not shown) connected to the video I / F 15 or a page printer connected to the printer I / F 17. (Not shown).
[0035]
Next, the operation of the image processing apparatus 10 will be described.
The image processing apparatus 10 determines a dropout section based on the coordinates of an edge to be currently processed and the coordinates of an edge selected from a scanning line adjacent thereto, and performs correction.
[0036]
FIG. 3 is a diagram illustrating a method of determining a dropout section.
FIG. 3A shows an example where no dropout occurs. In the figure, L1 and L2 indicate edges selected from the left outline, and R1 and R2 indicate edges selected from the right outline. L2 and R2 are edges selected from the intersection of the contour line and the scan line immediately above the scan line that selected L1 and R2. The area between L1 and R1 and the area between L2 and R2 are filled with this edge by scan conversion. If at least a part of the x-coordinate values of both areas overlap (continuously), dropout occurs. Does not occur.
[0037]
FIG. 3B shows an example in which a dropout occurs. In the figure, since the x-coordinate values of the region between L1 and R1 and the region between L2 and R2, which are filled by scan conversion, do not overlap, a dropout occurs between R1 and L2 in the x-axis direction.
[0038]
Therefore, the image processing apparatus 10 arranges the mappings L1 'and R1' of L1 and R1 on the same scanning line as L2 and R2 as shown in FIG. Compare the region between R2. As a result of this comparison, a portion where both regions overlap is a dropout, and this is determined as a dropout. In the following, the mappings L1 'and R1' are referred to as mark edges.
[0039]
Further, since the image processing apparatus 10 is mainly operated by the CPU 11, it is necessary to determine a dropout by a program. FIG. 3D shows an example of a case where a dropout is determined by a program. In this example, the edge has an integer element, +1 is set for the mark edge, and -1 is set for the edge. If the inclination of the contour is negative, -1 is set for the mark edge and +1 is set for the edge. When the mark edge and edge values set in this manner are added in ascending order of the x-coordinate (in order from left to right in the figure), a portion where the value becomes 2 is a region where a dropout has occurred. Can be determined.
[0040]
Here, the operation of the image processing apparatus 10 will be described with reference to FIGS.
4 to 7 are flowcharts showing the flow of the operation of the image processing apparatus 10, respectively.
[0041]
The image processing apparatus 10 reads image information and the like stored on a RAM (or RAM 12) not shown through an interface or the like not shown by the CPU 11. If the image information is a character code, outline font data is read from the ROM 13 or the external storage device 14 and the execution of the image generation program is started (FIG. 4, step 101).
[0042]
Next, the CPU 11 creates an edge list, a dropout registration list, and the like on the RAM 13 and initializes these lists (step 102). Subsequently, the CPU 11 executes the image conversion means 1 to convert the coordinates of the outline (outline) into a size desired to be output (step 103), and divides the outline into a plurality of short straight lines (the curved portion is approximated by a straight line). , Step 104).
[0043]
When the division of the contour is completed, the CPU 11 executes the intersection / dropout detecting means 2 to select an edge and a mark edge and register them in the edge list (step 105). At this time, the intersection / dropout detection means 2 also detects a dropout due to overlapping edges and registers it in a dropout registration list. Next, the dropout judging means 3 detects the dropout due to the mark edge and registers it in the dropout registration list (step 106). The details of the operations in steps 105 and 106 will be described later.
[0044]
Next, the CPU 11 executes the bitmap developing means 4 to generate a bitmap from the edge list (step 107), and after combining (inverting) the pixels of the coordinates registered in the dropout registration list (step 108). ), And output to the frame buffer 16 (step 109).
[0045]
Here, an output device (not shown) (such as a display or a page printer) checks the frame buffer 16 at regular time intervals or in response to an end signal from the CPU 11 and outputs a registered bitmap, so that the image processing device 10 End the operation.
[0046]
Next, details of the selection of the edge and the mark edge and the registration processing to the edge list in step 105 described above will be described.
The intersection / dropout detecting means 2 first sets the first (first in a preset order, whichever order may be used) contour line divided into straight lines (step 201 in FIG. 5), Is detected (step 202). Subsequently, the decimal point of the y coordinate value of the detected intersection is rounded down, and the decimal point of the x coordinate value is rounded to obtain pixel coordinates (step 203). The pixel coordinates are the same as the intersection point and the y coordinate, and are the closest pixels among the pixels (center points of the pixels) on the right side of the intersection point. Therefore, this pixel is regarded as an edge, and a mark edge is obtained from this edge. Edges are sequentially registered in an edge list (step 204).
[0047]
For registration in the edge list, first, the first edge is set (step 301 in FIG. 6), and the edge list to be registered is selected from the y-coordinate (or x-coordinate) of the coordinate value (step 302). If there is the same coordinate value as the edge to be registered in the edge list (set in step 301) (YES in step 303), the coordinate value is deleted from the edge list, and this is registered in the dropout. It is added to the end of the list (step 304). If the same coordinate value does not exist (NO in step 303), the coordinate value is added to the edge list (step 305).
[0048]
Next, 1 is added to the y-coordinate value of the edge to calculate a coordinate value indicating the pixel in the upper row (by subtracting 1 from the y-coordinate value to calculate a coordinate value indicating the pixel in the lower row). This is used as the coordinate value of the mark edge (step 306). Here, if the same coordinate value (the already registered mark edge) as the coordinate value of this mark edge is present in the edge list (YES in step 307), the coordinate value is deleted from the edge list (step 308). If the same coordinate value does not exist (NO in step 307), the coordinate value is added to the edge list (step 309).
[0049]
Until the last edge is registered (NO in step 310), the next edge is set (step 311), and the processing after selection of the edge list (step 302) is repeated until the last edge is registered. Is registered (YES in step 310), the process proceeds to step 205 (FIG. 5).
[0050]
When registering an edge and a mark edge, information on the inclination of the contour line corresponding to the edge is added as necessary.
[0051]
In each processing of steps 201 to 204 (including steps 301 to 311), the next contour is set (step 206) until the processing for the last contour is completed (step 205), and step 202 Then, the same processing is performed. When the processing for the last contour line is completed (YES in step 205), the processing in step 105 (FIG. 4) is completed, and the process proceeds to step 106.
[0052]
Next, the details of the detection of a dropout due to a mark edge and the registration processing to the dropout registration list in step 106 described above will be described.
The drop-out determination means 3 first sorts the edge list (step 401 in FIG. 7), and when the sorting is completed, sets the lowermost scanning line edge list as a processing target (step 402). Each element (edge, mark edge) is sequentially added (step 403). The values to be added are -1 and +1, respectively, for the edge and the mark edge with respect to the contour line having a positive gradient, and +1, -1 for the edge and the mark edge with respect to the contour line having a negative gradient.
[0053]
Next, a section where the added value of the element is 2 is detected (step 404), and if a section where the element is 2 is detected (YES in step 404), the coordinate value of the pixel of the detected section is added to the dropout registration list. Then, if no section in which the added value is 2 is detected (NO in step 404), no processing is performed.
[0054]
When the processing of the lowermost scanning line edge list is completed (NO in step 406), the one upper scanning line edge list is set (step 407), and the processing of step 403 and subsequent steps is performed to obtain the uppermost scanning line edge list. Is performed (YES in step 406), the detection of the dropout and the registration processing to the dropout registration list are completed, and the process proceeds to step 107.
[0055]
Next, an example of drawing characters by the image processing apparatus 10 will be described with reference to FIGS.
For example, when a character “0” is to be drawn in a certain size, the edge selected from the intersection of the scanning line and the outline is as shown in FIG. In FIG. 8, a pixel with a black dot at the center is the selected edge. Among the selected edges, pixels indicated by pixel coordinates (2, 6), (2, 7), (2, 8), and (2, 9) are edges selected from the two contour lines. is there.
[0056]
FIG. 9 is a diagram showing the contents of an edge list in which the edges shown in FIG. 8 are sequentially registered, and the pixel coordinates (2, 6) which are selected twice from two contour lines, All pixels are registered except for the pixels indicated by (2, 7), (2, 8), and (2, 9) (see steps 303 and 304 in FIG. 6).
[0057]
FIG. 10 is a diagram showing mark edges registered in the edge list. The mark edge is calculated based on the selected edge. In this case, a pixel at a coordinate obtained by adding 1 to the y coordinate value of the selected edge is set as a mark edge. Also, mark edges corresponding to the pixels selected by the doubly selected pixel coordinates (2, 6), (2, 7), (2, 8), and (2, 9) are not registered (FIG. 6). Steps 307 and 308).
[0058]
FIG. 11 is a diagram illustrating pixels registered in the dropout registration list.
In the figure, the pixels marked with “x” at the center are the pixel coordinates (2, 6), (2, 7), (2, 8) that are double selected because they are selected from two contour lines. ) And (2, 9) are registered as dropouts (see steps 303 and 304 in FIG. 6), and pixels (4, 2) and (4, 14) with "+" in the center are registered. ), (8, 2), and (8, 14) are registered dropouts detected by edges and mark edges. In the figure, the numbers shown at each pixel in the lower part of the pixel are the values that the edge and the mark edge have (the edge -1 when the slope of the contour is positive, the mark edge +1 and the slope of the contour is negative). When the edge +1 and the mark edge -1), the numbers shown in the upper row of the pixel indicate the values of the elements (edges, mark edges) in the pixels of each row having the same y coordinate in the x-axis direction (from left to right). The added value is shown.
[0059]
FIG. 12 shows a character “0” drawn based on the edge list and the dropout registration list, and it can be seen from FIG. 12 that the image processing apparatus 10 can draw a character without a dropout.
[0060]
In the above-described embodiment, the mark edge is calculated based on all the selected edges. However, as shown in FIG. 13, when the inclination of the outline is −1 or less or 1 or more, Since there is no dropout other than the dropout due to the edge selected from multiple contour lines, that is, the dropout detected using the mark edge, the mark edge is calculated according to the inclination of the contour line when calculating the mark edge. The processing relating to the mark edge can be omitted, and in this case, there is no inconvenience in dropout detection.
[0061]
In the above-described embodiment, the information of the dropout registration list is synthesized on the bitmap image by the bitmap developing means 4 (step 108 in FIG. 4). By registering the edge, it is possible to directly register the dropout in the edge list, and a raster-based output device such as a display may be able to execute the output as it is without expanding it to a bitmap. Therefore, depending on the configuration, the bitmap developing means 4 is not required.
[0062]
Further, the edge list and the dropout registration list may be formed as table values on the RAM 12 or may be formed so as to be registered as bitmaps.
[0063]
【The invention's effect】
As described above, according to the present invention, the position of the edge of the adjacent step is registered as a mark edge based on the edge selected from the intersection of the contour line and the scanning line, and the positional relationship between the edge and the mark edge is determined. Since it is configured to detect and correct dropouts,
The dropout can be corrected at high speed only by scanning from one direction while keeping the possibility of causing deformation of the character to be drawn low.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to the present invention.
FIG. 2 is a block diagram illustrating an actual configuration of the image processing apparatus 10.
FIG. 3 is a diagram showing a method for determining a dropout section.
FIG. 4 is a flowchart (1) showing a flow of the operation of the image processing apparatus 10.
FIG. 5 is a flowchart (2) showing a flow of the operation of the image processing apparatus 10.
FIG. 6 is a flowchart (3) showing the flow of the operation of the image processing apparatus 10.
FIG. 7 is a flowchart (4) showing the flow of the operation of the image processing apparatus 10.
FIG. 8 is a diagram showing edges selected from intersections of scanning lines and contour lines.
FIG. 9 is a diagram showing contents of an edge list in which edges shown in FIG. 8 are sequentially registered.
FIG. 10 is a diagram showing mark edges registered in an edge list.
FIG. 11 is a diagram showing pixels registered in a dropout registration list.
FIG. 12 is a diagram showing a character “0” drawn based on an edge list and a dropout registration list.
FIG. 13 is a diagram illustrating edges selected when the inclination of the contour is −1 or less, or 1 or more.
FIG. 14 is a diagram showing an outline of a character and a bitmap obtained from the outline.
FIG. 15 illustrates a shape of a pixel.
FIG. 16 is a diagram showing a method for determining whether each pixel is inside or outside a contour line.
FIG. 17 is a diagram showing a scanning line and a sub-scanning line.
FIG. 18 is a diagram illustrating a drawing example of a character.
FIG. 19 is a diagram showing an edge registration method.
FIG. 20 is a diagram showing an example of occurrence of dropout.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coordinate conversion means 2 Intersection / dropout detection means 3 Dropout determination means 4 Bitmap development means 10 Image processing device 11 CPU
12 RAM
13 ROM
14 External storage device 15 Video I / F (interface)
16 Frame buffer 17 Printer I / F (interface)

Claims (6)

An image corresponding to the character is developed on a bitmap by selecting a pixel closest to the scanning direction from an intersection between the contour line of the character to be drawn and the scanning line as an edge and inverting pixels between edges on the scanning line. Image processing method,
The first edge is sequentially selected on the target scanning line, and the second edge selected on the adjacent scanning line adjacent to the target scanning line and the second edge adjacent on the contour line among the second edges selected on the adjacent scanning line are selected. Moving an edge on the target scanning line in a direction orthogonal to the target scanning line, setting the moved position as a mark edge corresponding to the first edge;
A predetermined value is assigned to each of the first edge and the mark edge, and the predetermined values on the scan line of interest are sequentially added. Based on the result of the addition, a third edge, which is one of the first edges, is added. A region between an edge and a mark edge in which the correspondence between the third edge is set, and a fourth edge different from the third edge and corresponding to the fourth edge among the first edges An image processing method comprising: identifying an area that overlaps with an area between a mark edge to be overlapped; and detecting the overlapped area as a missing pixel. The scan line of interest is parallel to the x-axis on an xy plane represented by an x-axis and a y-axis orthogonal to the x-axis, and the adjacent scan line is more than the scan line of interest on the xy plane. Also, if the value of y is small,
If the inclination of the contour line is positive, -1 is assigned to the first edge and 1 is assigned to the mark edge,
If the inclination of the contour is negative, 1 is assigned to the first edge and -1 is assigned to the mark edge,
2. The image processing method according to claim 1, wherein an area where the addition result is 2 is detected as the overlapping area. The setting of the mark edge is as follows.
3. The image processing method according to claim 1, wherein the method is performed when the inclination of the contour is larger than -1 and smaller than 1. An image corresponding to the character is developed on a bitmap by selecting a pixel closest to the scanning direction from the intersection of the contour line of the character to be drawn and the scanning line as an edge and inverting pixels between edges on the scanning line. Image processing apparatus,
Edge selection means for selecting an edge on the scanning line;
The edge selected by the edge selecting means on the target scanning line is set as a first edge, and the edge selected on the adjacent scanning line adjacent to the target scanning line by the edge selecting means is set as a second edge. A second edge adjacent to the edge of the contour line on the contour line is moved on the target scanning line in a direction orthogonal to the target scanning line, and the moved position is set as a mark edge corresponding to the first edge. Edge setting means;
A predetermined value is assigned to each of the first edge and the mark edge, and the predetermined values on the scan line of interest are sequentially added. Based on the result of the addition, a third edge, which is one of the first edges, is added. A region between an edge and a mark edge in which the correspondence between the third edge is set, and a fourth edge different from the third edge and corresponding to the fourth edge among the first edges An image processing apparatus comprising: a pixel omission determination unit configured to specify an area where an area between a mark edge and a target mark edge overlaps, and detect the overlapping area as a pixel omission. The scan line of interest is parallel to the x-axis on an xy plane represented by an x-axis and a y-axis orthogonal to the x-axis, and the adjacent scan line is more than the scan line of interest on the xy plane. Also, if the value of y is small,
The pixel omission determining means,
If the inclination of the contour line is positive, -1 is assigned to the first edge and 1 is assigned to the mark edge,
If the inclination of the contour is negative, 1 is assigned to the first edge and -1 is assigned to the mark edge,
The image processing apparatus according to claim 4, wherein an area in which the addition result is 2 is detected as the overlapping area. The mark edge setting means,
The image processing apparatus according to claim 4, wherein the apparatus operates when the inclination of the contour is greater than −1 and less than 1.

Images