JP4182981B2 - Image smoothing method and resolution conversion method - Google Patents

Description

  In the present invention, when a predetermined number of narrow lines composed of subdivided pixels forming an output image are generated from each line forming an input image, the color arrangement of lines adjacent to the generation source line is reflected. The present invention relates to an image smoothing method for smoothing an image.

  When the resolution of a black-and-white binary image is increased, if the line that forms the image is simply copied to increase the number of lines, the step at the black-and-white boundary is enlarged as it is and becomes a large step, resulting in a reduction in image quality. . On the other hand, in the following patent document, a 3 × 3 matrix filter is applied to the original image to perform smoothing together.

  However, since the matrix filter only acts on the apex portion of the step portion of the black-and-white boundary, even if it is effective for the boundary having an angle of about 45 degrees as shown in the patent document, it is slightly different from the main scanning direction. There is a problem that the boundary that forms an angle is smoothed only on the stepped portion, and the boundary cannot be reproduced with a smooth straight line.

Already to this problem, the present inventor sequentially selects each of the lines forming the input image, and detects a matrix for detecting the start, end, and continuation of a stage having a height of one line from the selected target line. A step detecting step for extracting a continuous section of the same color that forms a step with the preceding and succeeding lines adjacent to the target line by the pattern matching process used, and a step in which the continuous section of the same color includes different lengths are included. An output image generation step that generates a predetermined number of narrow lines that are partly color-inverted based on the position and length of the same color continuous section from the target line so as to be reconstructed as overlapping narrow lines. Proposed an image smoothing method (Japanese Patent Application No. 2005-262829).
JP-A-8-16775

  The image smoothing method basically performs smoothing while maintaining the line thickness of the input image. However, depending on the use of the image or the user's preference, it is also required to change the line thickness (image density) during smoothing. Therefore, the present invention proposes a further improved image smoothing method to meet such a demand as follows.

  That is, the image smoothing method according to claim 1 sequentially selects each of the setting step for setting the color ratio of the subdivided pixels to be color-corrected for smoothing and the lines forming the input image. The same color continuity that forms a step with the preceding and following lines adjacent to the target line by pattern matching using a matrix that detects the start, end, and continuation of the step having a height of one line from the target line The same color is extracted from the line of interest so that the extraction step for extracting the section and the continuous section of the same color are reconstructed as a step with the number of stages according to the color ratio by the overlap of narrow lines including stages with different lengths. And a generation step for generating a predetermined number of narrow lines based on the start and end of the continuous section.

  According to a second aspect of the present invention, both the input image and the output image are two-color images, and the generation step includes the same color continuous section of the color on the side where the color ratio is set higher and the same color continuous section of the other side color Instead, a predetermined number of narrow lines are generated so as to be reconfigured as a larger number of steps.

  According to the present invention, the ratio (color ratio) of each color of pixels to be inverted for the sake of smoothing among the pixels (subdivided pixels) of the narrow line generated from the lines forming the input image is set. A predetermined number of narrow lines are generated from the target line so that the same color continuous sections extracted as steps are reconstructed as steps with the number of steps corresponding to the set color ratio. This is because, for example, when the image is a two-color image of A and B colors, if the color ratio of A is higher than that of B, the A and B colors that are adjacent to each other as the boundary of the stage In the same color continuous section, the A color side is reconfigured as a step having a larger number of steps, and the subdivided pixels that have undergone color conversion from A color to B color are more than those that have undergone color conversion from B color to A color. This means that there are a large number, and the B color as a whole becomes darker. Conversely, if the color ratio of B color is higher than that of A color, A color becomes darker. Therefore, by changing the setting of the color ratio, it is possible to smoothly change the thickness of the diagonal line so as to suit the purpose of the image or the user's preference.

  Although this smoothing method is preferably applied to a two-color image as in claim 2, it can also be applied to a three-color image. In the case of a three-color image, there are three combinations of upper and lower adjacent colors as the boundary between the steps of the same color continuous section, and there are three combinations of two colors in three colors. For each combination, a color ratio is set, A narrow line may be generated from the target line so that each of the same color continuous sections adjacent to each other in the combination is reconstructed as a step having the number of steps corresponding to the color ratio.

  The image smoothing method according to the present invention will be described below with reference to the drawings.

  An image smoothed by the image smoothing method of the present invention is defined as an aggregate of pixels that form a plurality of lines in the main scanning direction that are continuously arranged in parallel in the sub-scanning direction. Each pixel has a black or white color.

  Here, when defining a subdivision pixel having a size obtained by dividing the pixel into a plurality of sub-scanning directions, and further defining a narrow line as a subdivision pixel row continuous in the main scanning direction, According to the image smoothing method of the present invention, when a predetermined number of narrow lines forming the output image are generated from each of the lines forming the input image, the color arrangement of the lines adjacent to the generation source line is also reflected. Thus, it can be said that the image is smoothed.

  In the image smoothing method of the present invention, the step of setting the color ratio of the subdivided pixels to be color-corrected for smoothing, and each line in the main scanning direction of the input image as the target line Ln By sequentially performing pattern matching processing using a comparison matrix for detecting the start, end, and continuation of a stage having a height of one line while shifting an area having a predetermined spread around the line Ln as a center line The detection step of extracting the same color continuous section S forming a stage from the target line Ln with at least two pixels of the line adjacent to the target line Ln, and the same color continuous section S are made different in length. The color of a part of the target line is corrected so that it is reconstructed as a number of steps corresponding to the set color ratio by overlapping the narrow lines LSn including the steps. A narrow line was composed of a generation step of generating a narrow line having the same color arrangement and the line of interest.

The principle of this image smoothing method will be described with reference to FIG.
FIGS. 1A to 1C are diagrams showing examples of smoothing by the image smoothing method of the present invention for a black and white two-color image, and FIG. 1A shows a color ratio in which black is higher than white. (B) shows smoothing when a standard color ratio is set, and (c) shows smoothing when black has a lower color ratio than white. . Here, six narrow lines are generated from one line of the input image, one area surrounded by a thick line is one continuous section S of the same color, and one square is a vertical direction. Is a subdivided pixel, but the horizontal direction is a combination of an arbitrary number of subdivided pixels.

  In FIG. 1A, according to a color ratio in which black is higher than white, the same color continuous section S of black is a staircase of four narrow lines, and the same color continuous section S of white is a three-step narrow line. In step (b), according to the standard color ratio, the black same color continuous section S is a three-step narrow line staircase, and the white same color continuous section S is a four-step narrow line step. In step (c), according to the color ratio of black lower than that of white, the black same color continuous section S is a two-step narrow line staircase, and the white same color continuous section S is five steps. Reconstructed as a narrow line staircase. Note that the relationship between the color ratio and the number of steps of the staircase that reconstructs the same color continuous section S of black and white is not absolute but relative, and is not limited only to the correspondence in this example. The number of narrow lines that generate one line of the input image can be freely set.

  From these figures, it can be seen that the same black diagonal line becomes thicker in the order of (a), (b), (c), but at the same time, in FIG. Since the number of subdivided pixels that have undergone color conversion is larger than the number of subdivided pixels that have undergone color conversion from white to black, the black density is lowered. In FIG. It can also be seen that the black density increases because the subdivided pixels are fewer than the subdivided pixels that have undergone color conversion from white to black.

  This smoothing method is preferably applied to a two-color image, but can also be applied to a three-color image. In the case of a three-color image, there are three combinations of colors adjacent to each other as the boundary of the stage of the same color continuous section S. There are three combinations of two colors among the three colors. A color ratio is set for each combination. The narrow line may be generated from the target line so as to be reconfigured as the number of steps corresponding to the color ratio for the same color continuous sections S adjacent to each other in the upper and lower directions. More specifically, black, ash, and white are described as three colors: black is set to a higher color ratio for black and gray than black, and black is also white for black and white. If a lower color ratio is set and a standard color ratio is set for a combination of gray and white, smoothing is performed by making only the black diagonal line thicker than the standard diagonal line. The same applies to images of four or more colors.

  Next, the operation of each step constituting the smoothing method will be described with reference to FIGS. In any of the figures, two narrow lines are generated from one line of the input image. In particular, in the example of FIG. 2, the color ratio of black is higher than white as a parameter by the setting step. In the example of FIG. 3, a color ratio in which black is lower than white is set as a parameter in the setting step.

  In the detection step, an area having an area of 5 × 5 pixels with the target line Ln as a center line is shifted along the target line Ln in the main scanning direction, and adjacent to the target line Ln by pattern matching described later. The same color continuous section S that forms a step between the preceding and following lines Ln−1 and Ln + 1 is extracted. At this time, for example, by counting the number of shift movements, it is possible to grasp the start end of the stage as the pixel position on the target line Ln. The information of the same color continuous section S extracted here includes the start position P0, the end position P1, the side (left and right) and the direction (up and down) of the step, the color, and the like.

  The matrix used in this pattern matching is a stage having a step of one line formed by changing the color of a pixel in the middle of a line passing through the center of the matrix, its start end and its periphery, end and its periphery, or In this example, the pattern is a black-and-white pattern corresponding to 25 pixels forming an area of 5 × 5 pixels. In this embodiment, it is possible to extract a continuous portion of pixels that generate at least one line stage as the same color continuous section S by using such a matrix.

  However, for the purpose of extracting the same color continuous section S, it is sufficient that the color can be identified for a part of 25 pixels forming an area to be compared with the matrix, so that each matrix has a reference pattern for 25 pixels, You may comprise as a pair with the pattern for masks for always considering the contrast about the pixel unnecessary for a detection as a coincidence. It is only necessary to be able to identify some of the pixels forming the area because the matrix that detects the beginning of the black stage in the figure effectively determines the color of the 8 pixels in the area, It can be easily understood from the fact that the detected matrix effectively discriminates the colors of the five pixels in the area.

  In addition, when separately preparing groups of matrices for detecting the start, end, or continuation of a stage for each of black and white, the pixels of the control pattern are color-inverted with each other in the corresponding matrices. It may be related. Alternatively, in the pattern matching, it is possible to make the matrix common to each of black and white by determining whether the colors of the surrounding 24 pixels are the same with respect to the central pixel of the area. is there. Note that the size of the matrix is not limited to 5 × 5 pixels, and can be changed as appropriate.

  Next, the side where the step occurs and the direction will be described. The same color continuous section S includes a case where an upward step is formed on the left side, a case where an upward step is formed on the right side, and a case where a downward step is formed on the left side. In some cases, a downward step is formed on the right side.

  Also, when the width of the diagonal line formed by successive steps in the input image is 1 pixel, the same color continuous section S may form an upward step on the left side and a downward step on the right side. In some cases, an upward step is formed at the same time, and a downward step is formed on the left side.

  In addition, the same color continuous section S may form an upward step on the left side and an upward difference on the right side, or may form a downward step on the left side and a downward step on the right side. . However, in the embodiment, the smoothing process is not performed in these two cases.

  Next, in the generation step, before generating the narrow line LSn # x, based on the position and length of the same-color continuous section S, a color correction section for correcting the color arrangement in the narrow line LSn # x is calculated. Then, the start and end points are registered in the flag memory. That is, the color correction section is calculated in consideration of the set color ratio and the line count x based on the start position P0, end position P1, rising side and direction, and color of the stage, and corresponds to the value of the line count x. The start and end points are registered in the flag memory. Thereafter, the narrow line LSn # x is generated by inheriting the color arrangement of the pixel of the target line Ln as the color arrangement of the subdivided pixel. At this time, the subdivision is performed in the color correction section registered in the flag memory. The image is smoothed by correcting the color of the pixels. The maximum value m of the line count x is not limited, and the input image is increased in resolution in the sub-scanning direction accordingly.

A flag for registering a color correction section is generally as follows.
That is, in order to generate the narrow lines LSn # 0 to LSn # m corresponding to the target line Ln, it corresponds to the case where an upward white step is extracted on the left side or the right side as the same color continuous section S. The flag WU [0] to the flag WU [m] for registering a color correction section for correcting the color of the subdivided pixels of the narrow lines LSn # 0 to LSn # m from white to black and upward on the left side or the right side Corresponding to the case where the black stage is extracted, flags BU [0] to register a color correction section for correcting the color of the subdivided pixels of the narrow lines LSn # 0 to LSn # m from black to white. Corresponding to the case where the flag BU [m] and the downward white stage on the left side or the right side are extracted, color correction for correcting the color of the subdivided pixels of the narrow lines LSn # 0 to LSn # m from white to black Flag WL [0] to flag for registering the section Corresponding to the case where WL [m] and a downward black stage on the left or right side are extracted, a color correction section for correcting the color of the subdivided pixels of the narrow lines LSn # 0 to LSn # m from white to black It is sufficient to prepare flags BL [0] to BL [m] for registering.

  Here, a flag for registering a color correction section (note that what is actually registered in the flag memory is the start and end of the color correction section) and the calculation of the color correction section registered therein are shown in FIGS. This example will be specifically described.

  Table 1 corresponds to the example of FIG. 2 and shows examples of flags to be referred to when a color ratio of black is higher than that of white.

  In this case, when an upward black stage on the left side is extracted as the same color continuous section S, the flag BU [0] indicates the start end of the same color continuous section S and the end that is a half point of the same color continuous section S. Is registered in the flag memory, and when the upward black stage is extracted on the right side instead of the left side, the start point which is a half point of the same color continuous section S and the end point of the same color continuous section S are indicated by the flag BU [0 ] In the flag memory. In addition, when a black step facing downward on the left side is extracted as the same color continuous section S, the flag BL [1] indicates the start end that is a half point of the same color continuous section S and the end of the same color continuous section S. Is registered in the flag memory, and when the downward black stage is extracted not on the left side but on the right side, the flag BL [1 indicates the start end of the same color continuous section S and the end point that is a half point of the same color continuous section S. ] In the flag memory.

  Thereafter, when the narrow line LSn # 0 is generated, if the start / end of the color correction section is registered in the flag BU [0], the subdivision pixels in the section are color-corrected from black to white, When the narrow line LSn # 1 is generated, if the start / end of the color correction section is registered in BL [1], the subdivision pixels in that section are color-corrected from black to white.

  Table 2 shows an example of a flag to be referred to when the color ratio of black in FIG. 3 is lower than that of white.

  In this case, when an upward white step on the left side is extracted as the same color continuous section S, the flag WU [0] indicates the start end of the same color continuous section S and the end that is a half point of the same color continuous section S. Are registered in the flag memory, and when an upward white stage is extracted on the right side instead of the left side, the start point that is a half point of the same color continuous section S and the end point of the same color continuous section S are flag WU [0. ] In the flag memory. Further, when a white step facing downward on the left side is extracted as the same color continuous section S, the start end that is a half point of the same color continuous section S and the end of the same color continuous section S are set as a flag WL [1]. When registered in the flag memory and a downward white stage is extracted on the right side instead of the left side, the flag WL [1] indicates the start end of the same color continuous section S and the end point that is a half point of the same color continuous section S. Is registered in the flag memory.

  Thereafter, when the narrow line LSn # 0 is generated, if the start / end of the color correction section is registered in the flag WU [0], the subdivision pixels in the section are color-corrected from white to black, When the narrow line LSn # 1 is generated, if the start / end of the color correction section is registered in WL [1], the subdivision pixels in that section are color corrected from white to black.

  As yet another example, a flag for registering a color correction section and calculation of a color correction section registered in the flag will be described. As an example, a case where six narrow lines are generated from one line of the input image is shown.

  Table 3 shows an example of a flag to be referred to when black has a higher color ratio than white.

  Here, when an upward black stage on the left side is extracted as the same color continuous section S, the flag BU [0] indicates the start end of the same color continuous section S and the end that is a 4/6 point of the same color continuous section S. Is registered in the flag memory, and the start end of the same color continuous section S and the end that is a 3/6 point of the same color continuous section S are registered in the flag memory as the flag BU [1], and the start end of the same color continuous section S, The end that is a 2/6 point of the same color continuous section S is registered in the flag memory as a flag BU [2], and the start end of the same color continuous section S and the end that is a 1/6 point of the same color continuous section S are obtained. Register in the flag memory as flag BU [3]. Further, when an upward black stage is extracted on the right side instead of the left side, the flag memory stores the start end that is a 2/6 point of the same color continuous section S and the end of the same color continuous section S as the flag BU [0]. Are registered in the flag memory as the flag BU [1], and the end of the same color continuous section S is registered at the flag memory at the 4/6 point of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag BU [2], and the start end which is a 1/6 point of the same color continuous section S and the end of the same color continuous section S are flagged as the flag BU [ 3] is registered in the flag memory.

  When a downward black stage on the left side is extracted as the same-color continuous section S, the flag memory stores the start end of the same-color continuous section S and the end that is a 2/6 point of the same-color continuous section S as a flag BL [2]. Are registered in the flag memory as a flag BL [3], and the start end of the same color continuous section S and the end of the same color continuous section S are registered. The end of S, which is a 4/6 point, is registered in the flag memory as a flag BL [4], and the start end of the same color continuous section S and the end, which is the 5/6 point of the same color continuous section S, are registered in the flag BL [ 5] is registered in the flag memory. Also, when a downward black stage is extracted on the right side instead of the left side, the flag BL [2] is used as the flag memory with the start end that is a 5/6 point of the same color continuous section S and the end of the same color continuous section S as a flag memory. Is registered in the flag memory as a flag BL [3], and the end of the same color continuous section S is registered as a flag BL [3] at the 3/6 point of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag BL [4], and the start end that is a 2/6 point of the same color continuous section S and the end of the same color continuous section S are flag BL [ 5] is registered in the flag memory.

  When an upward white step on the left side is extracted as the same color continuous section S, the flag memory stores the start end of the same color continuous section S and the end that is 1/6 of the same color continuous section S as the flag WU [0]. Register with. Further, when an upward white step is extracted on the right side instead of the left side, the flag memory stores the start end that is the 5/6 point of the same color continuous section S and the end of the same color continuous section S as the flag WU [0]. Register with.

  When a white step facing downward on the left side is extracted as the same color continuous section S, the flag memory stores the start end of the same color continuous section S and the end that is 1/6 of the same color continuous section S as a flag WL [5]. Register with. Further, when a downward white step is extracted on the right side instead of the left side, the flag memory stores the start end which is the 5/6 point of the same color continuous section S and the end of the same color continuous section S as the flag WL [5]. Register with.

  Thereafter, the narrow line LSn # x is generated with reference to the corresponding flag, but the same color continuous section S from which the black stage is extracted is generated by the generated narrow lines LSn # 0 to LSn # 4, or By overlapping LSn # 1 to LSn # 5, it is reconfigured as five steps. For this reason, in this example, smoothing is performed so that the black diagonal line is thinner than the example of FIG.

  Table 3 shows an example of a flag to be referred to when the standard color ratio is set.

  Here, when an upward black stage on the left side is extracted as the same color continuous section S, the flag BU [0] indicates the start end of the same color continuous section S and the end that is a 2/6 point of the same color continuous section S. Are registered in the flag memory, and the start end of the same color continuous section S and the end of the same color continuous section S are registered in the flag memory as a flag BU [1]. Further, when an upward black stage is extracted on the right side instead of the left side, the flag memory stores the start end that is the 4/6 point of the same color continuous section S and the end of the same color continuous section S as the flag BU [0]. And the start end, which is a 5/6 point of the same color continuous section S, and the end of the same color continuous section S are registered in the flag memory as a flag BU [1].

  When a downward black stage on the left side is extracted as the same color continuous section S, the flag BL [4] is used as the flag memory with the start end of the same color continuous section S and the end of the same color continuous section S as the 1/6 point. And the start end of the same color continuous section S and the end of 2/6 of the same color continuous section S are registered in the flag memory as a flag BL [5]. Also, when a downward black step is extracted on the right side instead of the left side, the flag BL [4] is used as the flag memory with the start end, which is a 5/6 point of the same color continuous section S, and the end of the same color continuous section S as a flag memory. And the start end, which is a 4/6 point of the same color continuous section S, and the end of the same color continuous section S are registered in the flag memory as a flag BL [5].

  When an upward white step on the left side is extracted as the same color continuous section S, the flag memory stores the start end of the same color continuous section S and the end that is a 3/6 point of the same color continuous section S as the flag WU [0]. Are registered in the flag memory as a flag WU [1], and the start end of the same color continuous section S and the end of the same color continuous section S are registered. The end point which is 1/6 of S is registered in the flag memory as flag WU [2]. Further, when an upward white step is extracted on the right side instead of the left side, the flag memory stores the start end, which is a 3/6 point of the same color continuous section S, and the end of the same color continuous section S as a flag WU [0]. Is registered in the flag memory as a flag WU [1], and the end of the same color continuous section S is registered as a flag WU [1] at the 5/6 point of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag WU [2].

  When a white step facing downward on the left side is extracted as the same color continuous section S, the flag memory uses the start end of the same color continuous section S and the end that is 1/6 of the same color continuous section S as a flag WL [3]. Are registered in the flag memory as a flag WL [4], and the start end of the same color continuous section S and the end of the same color continuous section S are registered. The end point of 3/6 of S is registered in the flag memory as flag WL [5]. Further, when a downward white step is extracted on the right side instead of the left side, the flag memory stores the start end which is the 5/6 point of the same color continuous section S and the end of the same color continuous section S as the flag WL [3]. Is registered in the flag memory as flag WL [4], and the end of the same color continuous section S is registered as a flag WL [4] at the 3/6 point of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag WL [5].

  Thereafter, the narrow line LSn # x is generated with reference to the corresponding flag, and the same color continuous section S from which the black stage is extracted is generated by the generated narrow lines LSn # 0 to LSn # 2, or By overlapping LSn # 3 to LSn # 5, it is reconfigured as a three-step staircase. Therefore, in this example, the black diagonal line is smoothed so as to be a line having the same thickness as the example of FIG.

  Table 5 shows an example of a flag to be referred to when the standard color ratio is set.

  Here, when an upward black stage on the left side is extracted as the same color continuous section S, the flag BU [0] indicates the start end of the same color continuous section S and the end that is a 1/6 point of the same color continuous section S. Is registered in the flag memory. Further, when an upward black stage is extracted on the right side instead of the left side, the flag memory stores the start end which is the 5/6 point of the same color continuous section S and the end of the same color continuous section S as the flag BU [0]. Register with.

  When a downward black stage on the left side is extracted as the same-color continuous section S, the flag memory uses the start end of the same-color continuous section S and the end that is 1/6 of the same-color continuous section S as a flag BL [5]. Register with. Also, when a downward black stage is extracted on the right side instead of the left side, the flag BL [5] is set as the flag BL [5] at the start end that is the 5/6 point of the same color continuous section S and the end of the same color continuous section S. Register with.

  When an upward white step on the left side is extracted as the same color continuous section S, the flag memory stores the start end of the same color continuous section S and the end that is a 4/6 point of the same color continuous section S as the flag WU [0]. Are registered in the flag memory as a flag WU [1], and the start end of the same color continuous section S and the end of the same color continuous section S are registered. The end of 2/6 of S is registered in the flag memory as a flag WU [2], and the start of the same color continuous section S and the end of 1/6 of the same color continuous section S are flag WU [ 3] is registered in the flag memory. Further, when an upward white stage is extracted on the right side instead of the left side, the flag memory stores the start end that is a 2/6 point of the same color continuous section S and the end of the same color continuous section S as a flag WU [0]. Is registered in the flag memory as a flag WU [1], and the end of the same color continuous section S is registered as a flag WU [1] at the point of 4/6 of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag WU [2], and the start end that is a 1/6 point of the same color continuous section S and the end of the same color continuous section S are flag WU [ 3] is registered in the flag memory.

  When a white step facing downward on the left side is extracted as the same color continuous section S, the flag memory uses the start end of the same color continuous section S and the end that is a 2/6 point of the same color continuous section S as a flag WL [2]. Are registered in the flag memory as a flag WL [3], and the start end of the same color continuous section S and the end of the same color continuous section S are registered. The end of S, which is a 4/6 point, is registered in the flag memory as a flag WL [4], and the start end of the same color continuous section S and the end, which is a 5/6 point of the same color continuous section S, are flag WL 5] is registered in the flag memory. Also, when a downward black stage is extracted on the right side instead of the left side, the flag memory stores the start end which is the 5/6 point of the same color continuous section S and the end of the same color continuous section S as the flag WL [2]. Is registered in the flag memory as flag WL [3], and the end of the same color continuous section S is registered as a flag WL [3] at the point of 3/6 of the same color continuous section S. A certain start end and the end of the same color continuous section S are registered in the flag memory as a flag WL [4], and the start end that is a 2/6 point of the same color continuous section S and the end of the same color continuous section S are registered in the flag WL [ 5] is registered in the flag memory.

  After that, the narrow line LSn # x is generated with reference to the corresponding flag, but the same color continuous section S from which the black stage is extracted is generated by the generated narrow line LSn # 0, LSn # 1, or By overlapping LSn # 4 and LSn # 5, it is reconfigured as a two-step staircase. Therefore, in this example, the black diagonal line is smoothed so as to be a line having the same thickness as the example of FIG.

  It should be noted that the specific examples described above are merely examples described, and the calculation method of the color correction section can be freely changed, and should be determined in consideration of the appearance of the output image.

  FIG. 4 shows that the same color continuous section S from which black stages are extracted is divided into four stages of narrow lines LSn # 0 to LSn # 3 or LSn # 2 to LSn # 5 by six narrow lines. It is drawing explaining the method of reconstruction about the example to reconfigure | reconstruct, and has shown the flag referred when producing | generating each narrow line LSn # 0-LSn # 5.

Next, an example of an apparatus that executes the above-described image smoothing method of the present invention will be described.
FIG. 5 is a block diagram illustrating a schematic configuration of an example of an apparatus.

  This image smoothing method apparatus M extracts the same color continuous section S that forms a step of one line height from the input image, and the position of the same color continuous section S detected by the stage detection means 11. A color correction section is calculated based on the length, and the output image generation means 12 generates narrow lines LSn # 0 to LSn # m obtained by correcting the color correction section from the target line Ln, and the color for smoothing. And a color ratio register 13 for setting the color ratio of the subdivided pixels to be corrected.

  The stage detection unit 11 is extracted by a line memory unit 11a configured by a shift register or the like that receives and shifts pixel data of an input image for each control clock, and an area extraction unit 11b set in the line memory unit 11a. A pattern matching unit that performs pattern matching on the pixel data in the area and extracts the same color continuous section S.

  The output image generation unit 12 calculates a color correction section based on the start and end of the same color continuous section S detected by the stage detection unit 11, and the color correction section calculation unit 12a. A line counter unit 12b that outputs a line count x that specifies one of the narrow lines LSn # 0 to LSn # m, a flag memory BU (12c) that registers the calculated color correction section, and a flag memory WU (12d) ), A flag memory BL (12e), a flag memory WL (12f), logic gates G1 and G2, and a color correction unit 12g that receives pixels of the input image and outputs segmented pixels of the output image.

(A) to (c) show examples of smoothing when different color ratios are set in the image smoothing method of the present invention. Another example of smoothing by the image smoothing method of the present invention. FIG. 6 is still another example of smoothing by the image smoothing method of the present invention. The figure explaining the method to reconfigure | reconstruct the same color continuous area. The block diagram explaining the schematic structure of the apparatus to which this invention is applied.

Explanation of symbols

13 Color ratio register Ln Line of interest LSn Narrow line M Image smoothing device S Same color continuous section

Claims (2)

When a predetermined number of narrow lines consisting of subdivided pixels that form the output image are generated from each line that forms the input image, the image is smoothed by reflecting the color arrangement of the lines adjacent to the generation source line In the image smoothing method to
A setting step for setting the color ratio of the subdivided pixels to be color-corrected for smoothing;
Each line forming the input image is sequentially selected and adjacent to the target line by a pattern matching process using a matrix that detects the start, end, and continuation of a stage having a height of one line from the selected target line. An extraction step of extracting continuous sections of the same color that form a step with the previous and subsequent lines;
The same-color continuous section is reconstructed from the target line so that the same-color continuous section is reconstructed as a step having the number of steps according to the color ratio by overlapping the narrow lines including the steps having different lengths. An image smoothing method comprising: a generation step of generating the predetermined number of narrow lines based on a start end and an end. In claim 1, both the input image and the output image are two-color images,
The generation step is
The predetermined number of narrow lines so that the same color continuous section of the color on the side where the color ratio is set higher is reconstructed as a step having a larger number of steps than the same color continuous section of the other color. An image smoothing method comprising: generating an image.

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