JPH11331605A - Method for processing image correction im printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process the edge part of a binary picture including an intermediate density by means of smoothing and to evade an adverse effect owing to a smoothing processing in the image or the like by executing the smoothing processing when the image density of high density side areas and that of low density areas within a prescribed range in the circumference of the pixels to be corrected in an edge part including the pixels to be corrected are uniform. SOLUTION: The prescribed range 1 is provided with the low density areas 3 which indicate the area of the pixels with the uniform low density and the high density areas 4 which indicate the area of the pixels with the uniform high density. The low and high density areas 3 and 4 are divided by an edge line 5 being a line which indicates the edge part of image data. When the state of the pixels within the prescribed range are divided into the uniform (one kind) high density areas 4, the image data is considered to be binary image data so that the smoothing processing is executed to the edge part in the circumference of the edge line 5. In this case, a printing processing is executed after the smoothing processing in only binary image data and printing is executed as it is concerning multi-valued image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image correcting method for a printing device such as a laser printer and a digital copier.

[0002]

2. Description of the Related Art Conventionally, when image data in which binary data and multivalued data are mixed is input, a binary image based on the pixel density from the image data is used in order to avoid an adverse effect on the multivalued image data. There is known a method of extracting data (extraction processing), performing smoothing processing only for an edge portion of a binary image for image correction, and outputting the result from a printing apparatus.

[0003]

However, since the above-described extraction processing for extracting a binary image is performed based on the density of the pixels of the image data, the density of the pixels in color characters is insufficient due to the color. In some cases, the image cannot be extracted as a value image, and in some cases, a line image cannot be extracted as a binary image due to insufficient pixel density. In these cases, the smoothing process is not performed even for a binary image. was there. On the other hand, in the image data of an image such as a photograph other than the above-described characters and line drawings, even if the density of the pixel satisfies the condition for performing the smoothing process, the smooth gradation of the image image is reproduced. No smoothing process is required. SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-described drawbacks of the related art, and is intended to input image data in the form of bitmaps using pixels of multi-valued gradation including binary, and to detect the edge of the image data. It is an object of the present invention to provide an image correction processing method of a printing apparatus that can detect only an edge of an image of intermediate density such as a color character or a line image and perform a smoothing process when detecting a portion.

[0004]

According to a first aspect of the present invention, there is provided an image correction processing method for a printing apparatus, comprising the steps of: In a printing apparatus capable of inputting image data, detecting an edge portion of the image data, and performing a smoothing process for correcting the edge portion as necessary, a predetermined peripheral portion including a correction target pixel of the edge portion is provided. The smoothing process is performed when the pixel density of the high density side area and the pixel density of the low density area in the range are uniform. An image correction processing method for a printing apparatus according to the present invention according to claim 2, wherein bitmap-like image data is input by pixels of multi-level gradation including binary, and an edge portion of the image data is detected. In a printing apparatus capable of executing a smoothing process for correcting the edge portion as necessary, at least one of a pixel density of a high density region and a pixel density of a low density region in a correction target pixel of the edge portion and a predetermined range around the pixel to be corrected. A smoothing process is executed when either one is within a predetermined range.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a diagram illustrating an example of a state of pixels in a predetermined range around a pixel of interest at an edge portion of binary image data. As shown in FIG.
Indicates a matrix (detection region) of five vertical and horizontal pixels around the pixel of interest 2. Predetermined range 1
Inside, a low-density area 3 showing a uniform low-density pixel area
And a high-density area 4 indicating a uniform high-density pixel area. The low-density area 3 and the high-density area 4 are separated by an edge line 5 which is a line indicating an edge of the image data. Note that the target pixel 2 in this case is a pixel included in the high density region 4 and adjacent to the edge line 5. When the state of the pixels within the predetermined range is divided into a uniform (one type) low-density region 3 and a uniform (one type) high-density region 4 as shown in FIG. 1, the image data is a binary image. Since it is considered to be data, a smoothing process is performed on the edge portion around the edge line 5.

FIG. 2 is a diagram showing an example of the state of pixels in a predetermined range around a pixel of interest at an edge portion of image data in which a high-density area is multi-valued. As shown in FIG. 2, the predetermined range 11 is defined by five vertical and horizontal areas around the pixel of interest 12.
The matrix of pixels (detection area) is shown. Within the predetermined range 11, there are a low-density area 33 indicating a uniform low-density pixel area and a high-density area 14 indicating a multi-valued high-density pixel area. The low-density area 13 and the high-density area 14 are separated by an edge line 15 which is a line indicating an edge of the image data. High density region 1 in this case
Reference numeral 4 denotes eight pixels having the same density as the target pixel 12, four pixels 16 to 19 having a lower density than the target pixel 12, and two pixels 20 and 21 having a higher density than the target pixel 12 in the high density region.
This is a multi-valued high density area where pixels exist. Accordingly, since the image data in the case of FIG. 2 is not considered to be binary, the smoothing processing is not performed on the edge portion around the edge line 15. Although the low-density area 13 is a uniform pixel area in FIG. 2, the low-density area may have a multi-valued low density. That is, at least the low density region 13 and the high density region 1
It is sufficient that a multi-level density exists in one of the four.
As shown in FIG. 2, when either the low density area or the high density area, or both areas have a plurality of pixel densities, there is a high probability that the image is an image other than a character or a line drawing. (Correction processing) is excluded.

FIG. 3 is a flowchart showing one embodiment of a procedure for determining whether or not to perform smoothing processing on image data as shown in FIGS. Step S
1 separates a detection area (predetermined range) of 5 pixels in the vertical and horizontal directions around the pixel of interest at the edge portion of the image data, and detects a density variation between the pixel of interest and the other pixels. In step S2, it is determined whether or not the pixel density of the low density area in the detection area is uniform. If the pixel density of the low density area is uniform (step S2: YE
If the pixel density of the low density area is not uniform (step S2: NO), the process proceeds to step S3.
Go to 5. In step S3, it is determined whether or not the pixel density of the high-density area in the detection area is uniform. If the pixel density of the high-density area is uniform (step S3: YE
If the pixel density of the high density area is not uniform (step S3: NO), the process proceeds to step S4.
Go to 5. In step S4, a printing process is performed after performing a smoothing process on an edge portion of the detection region of the image data. A step S5 carries out a printing process with the image data as it is. By performing the determination in accordance with the flowchart of FIG. 3, the smoothing process is performed only for the binary image data as shown in FIG. 1, and then the printing process is performed. For the multi-valued image data as shown in FIG. Can be done.

FIG. 4 is a diagram showing an example of a case where the smoothing process in step S4 in FIG. 3 is performed on pixels in a predetermined range (detection area) in FIG. As shown in FIG. 4, the predetermined range 31 indicates a matrix (detection region) of five vertical and horizontal pixels around the target pixel 32. Within the predetermined range 31, there are a low-density area 33 indicating a low-density pixel area and a high-density area 34 indicating a high-density pixel area. The low-density area 33 and the high-density area 34 are separated by an edge line 35 which is a line indicating an edge portion of the image data. In this case, since the low-density area 33 and the high-density area 14 have been subjected to the smoothing process, the area between the two densities is further divided into two, and the second low-density is slightly darker than the original low-density pixel. Then, a second high density slightly lower than the original high density pixel is set. Then, the target pixel 32 and the pixel 38 in the high-density area 34, the pixels 36 and 37 in the low-density area 33 are set to the second low density, and the pixel 39 in the high-density area 34 is set to the second high density. Next, as described above, smoothing processing is performed not only for simple binary image data composed of uniform low-density and uniform high-density pixels, but also for the density of pixels in the low-density area and the high-density area. In the following, a description will be given of a case where there is a variation in the binary density of the pixel of the above, and the respective variations have a density within a predetermined allowable range. Also in this case, it is required to execute the smoothing process on the edge portion as in the case of the binary image data described above.

FIG. 5 shows a case where the pixels of the high-density region and low-density region of the binary image data shown in FIG. 1 vary within a predetermined allowable range, and a case where the multi-valued image shown in FIG. 9 is a flowchart illustrating an embodiment of a procedure for determining whether to perform a smoothing process when image data is input. In step S11, for each of the high-density area and the low-density area, an allowable range of the variation of the density data is set and input. In step S12, a detection area (predetermined range) of 5 pixels in the vertical and horizontal directions around the pixel of interest at the edge portion of the image data is separated, and density variations of the pixel of interest and other pixels are detected. Step S1
3 judges whether the pixel density of the low density area in the detection area is uniform or not, and if the pixel density of the low density area is uniform (step S13: YES), step S3 is performed.
When the process proceeds to step S14, and the pixel density in the low density region is not uniform (step S13: NO), the process proceeds to step S16.
In step S14, it is determined whether or not the pixel density of the high-density area in the detection area is uniform. If the pixel density of the high-density area is uniform (step S14: YES), the process proceeds to step S15. If the pixel density of the density area is not uniform (step S14: NO), step S1
Proceed to 6. In step S15, the printing process is performed after performing the smoothing process on the edge of the detection area of the image data. A step S16 carries out a printing process with the image data as it is. By performing the determination in accordance with the flowchart of FIG. 5, even if the high-density area and the low-density area of the binary image data vary within a predetermined range as shown in FIG. Then, the printing process can be directly performed on the multi-valued image data as shown in FIG. The above detection area is 5 pixels vertically and 5 pixels horizontally with the target pixel as the center. However, the detection area in the present invention is not limited to this, and it is necessary to improve the detection accuracy and avoid excessive detection. The size and shape of the area may be changed. Further, similarly to the above, the reference value of the density detection may be changed to an arbitrary value.

[0010]

As described above, according to the present invention, the detection area is separated around the target pixel at the edge of the image data, and it is determined whether the pixel density of the high density area and the pixel density of the low density area are uniform. It is determined whether the image data is an image image or a binary image including a variation in a predetermined range by detecting whether the pixel density is within the range of. In other words, the smoothing process is not performed on the edge portion, and the smoothing process is performed on the edge portion of the image of the binary image including the intermediate density such as the color character and the line drawing. This makes it possible to avoid the adverse effect of performing the smoothing process on an image or the like, and to perform the smoothing process only on a color character or a line drawing portion. Furthermore, since the detection range and the allowable range of the density data can be arbitrarily set, even if image data such as a case where character data is overlapped on an image image is input, it is determined that the image data is an edge of a character or a line drawing. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a state of pixels in a predetermined range around a pixel of interest at an edge portion of binary image data.

FIG. 2 is a diagram illustrating an example of a state of pixels in a predetermined range around a pixel of interest at an edge portion of multivalued image data in a high-density region.

FIG. 3 is a flowchart showing an embodiment of a procedure for determining whether or not to perform a smoothing process on image data as shown in FIGS. 1 and 2;

FIG. 4 is a diagram illustrating an example of a case where a smoothing process in step S4 in FIG. 3 is performed on pixels in a predetermined range (detection region) in FIG. 1;

5 shows a case where pixels in a high-density area or a low-density area of the binary image data shown in FIG. 1 vary within a predetermined allowable range, and a case where multi-valued image data as shown in FIG. 9 is a flowchart illustrating an embodiment of a procedure for determining whether to perform a smoothing process when an input is made.

[Explanation of symbols]

1, 11, 31... Predetermined range (detection range), 2, 1
2, 32: target pixel, 3, 13, 33: low density area, 4, 14, 34: high density area, 5, 15, 3
5: Edge line, 16 to 19: Pixel with density lower than the pixel of interest, 20 to 21: Pixel with density higher than the pixel of interest, 36 to 38: Pixel of second low density, 39・ ・
.Second high-density pixels

Claims (2)

[Claims] 1. A smoothing process for inputting bitmap image data of pixels of multi-level gradation including binary, detecting an edge portion of the image data, and correcting the edge portion as necessary. In an executable printing apparatus, the smoothing process is performed when the pixel density of the high density side area and the pixel density of the low density area in the predetermined range around the edge portion including the pixel to be corrected are uniform. An image correction processing method for a printing apparatus characterized by the following. 2. Smoothing processing for inputting bitmap-like image data by pixels of multi-level gradation including binary, detecting an edge portion of the image data, and correcting the edge portion as necessary. In an executable printing apparatus, a smoothing process is performed when at least one of the pixel density of the high density area and the pixel density of the low density area in a predetermined range around the pixel to be corrected in the edge portion and a predetermined range around the pixel is within a predetermined range. And an image correction processing method for a printing apparatus.