JPH1067142A - Method and apparatus for recording image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a resolution, and improve image quality by restricting notches of a contour in a method and an apparatus for recording images. SOLUTION: Multi-gradation image data are quantized, and converted to a quantized pixel pattern. A smoothed point of an image obtained by the quantization is detected. Pixels of the detected smoothed point are interpolated. A contour of the quantized image is thus corrected. At this time, quantization pixel patterns (A)-(H) stored in a memory are replaced with pixel patterns (I)-(P) having the smoothed point of the detected quantized image quantized. Each pixel pattern is stored in the memory as four-bit image information and constituted of a (4*2) matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method and an image recording apparatus, and more particularly, to a high-quality image recording by a dot matrix type recording method using area gradation and a recording method for visually smoothing. The present invention relates to an image recording method and an image recording device.

[0002]

2. Description of the Related Art In recent years, OA devices such as personal computers and word processors have become widespread, and various types of devices for printing out image information and the like input by these devices have been developed. Above all, a printing apparatus of a dot matrix system such as an ink jet system, a wire dot system, and a thermal system is a relatively inexpensive and easily space-saving recording device, and is therefore the most widely used digital recording system at present.

[0005] In a recording apparatus of the digital recording system, since it is impossible to express an analog gradation in a dot unit, a halftone is artificially represented by an area where a plurality of dots cover the paper surface.

[0004] Further, in image formation by a dot matrix type recording apparatus, since an image is formed by combining dots, a jagged feeling may occur in an outline such as a hatched portion of the image, and the image quality may be degraded. In some dot matrix type recording apparatuses aiming at extremely high-quality output, as a measure for alleviating the jagged portion, as disclosed in Japanese Patent Application Laid-Open No. H02-112966, etc. The matching detection patterns of a plurality of (n * m) pixel sizes set in advance are compared with the printing original image, and a position where the matching pattern matches the original image is set uniquely to the matching pattern. The jagged feeling is mitigated by performing interpolation processing on the original image in accordance with the following rules.

[0005]

However, in the prior art interpolation processing of the original image for reducing the jagged portion, it is necessary to newly provide interpolated pixel data (matching detection pattern), so that the memory capacity is increased and the cost is increased. In addition, there is a problem that it takes time for the processing speed.

Further, by quantizing multi-gradation input image data into three or more values, halftone is expressed by using a plurality of dots at different landing positions for one pixel to improve gradation. It is very difficult to achieve both suppression of jaggedness in the outline of an image. That is, although the improvement of the gradation can be realized by the quantization of three or more values, this has no effect on the jaggedness of the outline and does not improve the resolution.

Accordingly, the present invention can express many halftones to prevent a rise in cost and a reduction in processing speed due to an increase in the capacity of a memory and improve gradation, and furthermore, a jagged outline of a character or the like. It is an object of the present invention to provide an image recording method and an image recording apparatus capable of realizing high image quality by a dot matrix recording method by suppressing a feeling.

[0008]

According to a first aspect of the present invention, there is provided a method for quantizing multi-gradation image data and converting the image data into a quantized pixel pattern. An image recording method comprising: detecting a smoothed portion of an image obtained by quantization; and correcting the contour of the quantized image by interpolating the detected pixel of the smoothed portion. In the correction step, the quantized pixel pattern at the smoothed portion of the quantized image is replaced with a smoothing pixel pattern stored in a storage unit.

Further, in the method according to the present invention, the quantized image is constituted by a quantized pixel pattern, and the quantized pixel pattern and the smoothing pixel pattern are different from each other. Are stored as 4-bit pixel information, and both pixel patterns are configured by a (4 * 2) matrix.

Further, in the method according to the present invention, in the detecting step, (n * m) matrix (m, n is a positive integer of 3 or more) of the quantized image (n * M). The configuration is such that the smoothed portion is detected by comparing a part of the image (N * M) matrix smaller than the detection pattern of the (N * M) matrix.

Further, in the method according to the present invention, when the part of the image includes a halftone, the comparison with the detection pattern is not performed.

According to a fifth aspect of the present invention, the pixels at the 2nd to (n-1) th positions in the horizontal direction and the 2nd to (m-1) th positions in the vertical direction of the detection pattern are interpolated. The target configuration was adopted.

Further, in the method according to the present invention, in the detecting step, a region which does not include an outline in the quantized image is primarily detected, and a region other than the region which does not include the outline is detected. The configuration is such that comparison with the detection pattern is performed.

Further, in the method according to the present invention, the primary detection is performed by giving priority to the comparison between a pattern having no dots and a partial image of the quantized image.

In the method according to the present invention, a quantization step of quantizing multi-gradation image data and converting the image data into a quantized pixel pattern is provided. A black detection step of detecting the black character portion, a detection step of detecting a smoothed portion of the quantized image when the black character portion is detected, and interpolating pixels of the detected smoothed portion to detect the quantized image. A correcting step of correcting an outline, wherein in the correcting step, the quantized pixel pattern of the smoothed portion of the quantized image is stored in a storage unit for smoothing. The configuration is such that the pixel pattern is replaced.

In order to achieve the above object, in the apparatus according to the ninth aspect of the present invention, a quantizing means for quantizing multi-gradation image data and converting it into a quantized pixel pattern is provided. An image recording apparatus comprising: a detecting unit that detects a smoothed portion of an obtained image; and a correcting unit that interpolates a pixel of the detected smoothed portion to correct an outline of the quantized image. By the correction means, the quantized pixel pattern of the smoothed portion of the quantized image,
The pixel pattern for smoothing stored in the storage unit is replaced.

Further, in the apparatus according to the present invention, the quantized image is constituted by a quantized pixel pattern, and the quantized pixel pattern and the smoothing pixel pattern are different from each other. Are stored as 4-bit pixel information, and both pixel patterns are configured by a (4 * 2) matrix.

Further, in the apparatus according to the present invention, the detecting means may select (n * m) a matrix (m, n is a positive integer of 3 or more) from the (n * m) matrix of the quantized image. * M). The configuration is such that the smoothed portion is detected by comparing a part of the image (N * M) matrix smaller than the detection pattern of the (N * M) matrix.

Further, in the apparatus according to the present invention, when the partial image includes a halftone, the comparison with the detection pattern is not performed.

Further, in the apparatus according to the present invention, the pixels at the 2nd to (n-1) th positions in the horizontal direction and the 2nd to (m-1) th positions in the vertical direction of the detection pattern are interpolated. The target configuration was adopted.

Further, in the apparatus according to the present invention, the detection means primarily detects a region not including the contour in the quantized image, and detects a region other than the region not including the contour. The configuration is such that comparison with the detection pattern is performed.

Further, in the apparatus according to the present invention, the primary detection is preferentially performed by comparing a pattern having no dots with a partial image of the quantized image.

Further, in the apparatus according to the present invention, a quantization means for quantizing multi-gradation image data and converting it into a quantized pixel pattern, and a black character portion from the quantized image are provided. A black detection unit that detects a black character portion, a detection unit that detects a smoothed portion of the quantized image, and a pixel of the detected smoothed portion by interpolating the detected pixel of the quantized image. Correction means for correcting the contour, wherein the correction means converts the quantized pixel pattern of the smoothed portion of the quantized image to a smoothing portion stored in a storage means. The pixel pattern is replaced.

Further, in the apparatus according to the present invention, the recording is performed using an ink jet type recording head which discharges ink by thermal energy.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing the structure of a main part of a first embodiment of an ink jet recording apparatus to which the present invention is applied.

In FIG. 1, the ink jet unit 1
Reference numeral 1 denotes a recording head in which ejection port arrays for ejecting ink are arranged. The inkjet unit 11 is installed on a carriage 13. For example, a recording material P made of a recording paper, a plastic thin plate or the like is nipped by a discharge roller 17 via a not-shown conveying roller, and is driven by a not-shown conveying motor to be sent in the direction of arrow F. The carriage 13 is guided and supported by the guide shaft 12 and an encoder (not shown). The carriage 13 is
It is reciprocated along the guide shaft 12 by the drive of the carriage motor 15 via the drive belt 14.

A heating element (electric-heat conversion means) for generating thermal energy for ink ejection is provided inside the ink ejection port (liquid passage) of the ink jet unit 11. Then, in accordance with the read timing of the encoder, the heating element is driven based on the recording signal to discharge ink from the ink discharge port, and the ink droplets fly and adhere on the recording material P to form an image. You can do it.

At the home position HP of the carriage selected outside the recording area, a recovery unit having a cap 16 is provided. When recording is not performed, the carriage 13 is moved to the home position HP, and the cap unit 16 seals the ink discharge port forming surface of the ink jet unit 11 to fix the ink due to evaporation of the ink solvent, or to remove dust, paper dust, or the like. Prevents clogging due to adhesion of foreign matter.

The capping function of the cap section 16 is to prevent the ejection failure or clogging of the ink ejection port having a low recording frequency due to thickening or sticking of the ink, and to prevent the cap from being separated from the ink ejection port. It is used in a preliminary ejection mode for ejecting ink to the unit 16. Or,
The suction pump is operated in the capped state to suck the ink from the ink ejection port, and is used for the ejection recovery of the ink ejection port having the ejection failure. In addition, by disposing a cleaning blade at a position adjacent to the cap portion 16, it is possible to clean (wiping) the ink discharge port forming surface of the inkjet unit 11.

FIG. 2 is a block diagram showing a configuration of a control circuit provided in the ink jet recording apparatus of FIG.

In FIG. 2, each component connected to the main bus line 205 includes an image input unit 203 that accesses the main bus line 205, an image signal processing unit 204 corresponding to the image input unit 203, and a CPU ( Central processing unit)
200, a software processing unit, an operation unit 206, a recovery system control circuit 207, an ink jet head temperature control circuit 21
4. It is roughly divided into a hardware processing unit such as the head drive control circuit 215.

A CPU (Central Processing Unit) 200 usually has a ROM 201 and a RAM 202 and controls the recording head 213 to perform recording by giving appropriate recording conditions to input data. Also, in the ROM 201,
A program for executing the head recovery timing chart is stored in advance, and recovery conditions such as preliminary discharge conditions are given to the recovery system control circuit 207, the recording head 213, the heat retention heater 213b, and the like as necessary. The ROM 201 stores in advance a program for executing the processing of the flowchart of FIG.

The recovery system motor 208 includes a recording head 213 as described above, a cleaning blade 209, a cap 210, and a suction pump 21 which are opposed to and separate from the recording head 213.
1 is driven. The head drive control circuit 215 drives the above-described heating element 213a for ink ejection of the recording head 213, thereby causing the recording head 213 to perform preliminary ejection and ink ejection for recording.

On the other hand, the substrate on which the heating element 213a for ink ejection of the recording head 213 is provided is provided with a heat retaining heater 213b so that the ink temperature in the recording head 213 is adjusted to a desired set temperature. You can do it. The thermistor 212 is also provided on the above-mentioned substrate, and is for measuring the substantial ink temperature inside the recording head 213. The thermistor 212 may be provided externally, not on the substrate, or may be near the periphery of the recording head 213.

In the recording apparatus according to the first embodiment of the present invention configured as described above, a multi-gradation input image is multi-valued image data having a resolution of 300 * 300 dpi, and one pixel has a different landing position. The following control is performed by the control circuit of FIG. 2 in order to achieve the improvement of the gradation by expressing the halftone using a plurality of dots and the suppression of the jaggedness by correcting the outline of the image.

FIG. 3 is an explanatory diagram for explaining a quantized pixel pattern and a pixel pattern to be smoothed in the first embodiment of the present invention.

These pixel patterns are composed of 16 types of pixel patterns shown in FIGS. 3 (A) to 3 (P) constituted by a matrix of (4 * 2) per pixel.
The data capacity previously stored in the memory such as the AM 202 is 4
Is a bit. The multi-gradation input image data is quantized into eight-level (level) data, and is converted into image data formed by eight types of quantized pixel patterns shown in FIGS. FIG. 3A shows a pattern without dots, FIG. 3H shows a pattern with all eight dots, and the other patterns are halftone patterns. FIGS. 3 (I) to 3 (P) show eight types of pixel patterns to be smoothed, and are halftone patterns having two dots or four dots.

FIG. 4 is an explanatory diagram for explaining a detection pattern for detecting a smoothed portion in the first embodiment of the present invention.

This detection pattern consists of a matrix having a pixel size of (3 * 3) smaller than (5 * 5).
1) to (A-4), (B-1) to (B-4), (C-
Twelve types of 1) to (C-4) are prepared.

First, the multi-gradation input image data is quantized into 8-level (level) data, and FIG.
The image data is converted into quantized image data formed by the pixel pattern shown in (H).

FIG. 5 is an explanatory diagram for explaining an image in which multi-gradation input image data is quantized into eight values in the first embodiment of the present invention.

FIG. 5A is an example of multi-gradation input image data quantized into eight values of a matrix of (5 * 5) pixel size. Each pixel has one of the quantized pixel patterns shown in FIGS. 3A to 3H. FIG.
(B) to (J) are matrix portions having a pixel size of (3 * 3) smaller than (5 * 5), and are composed of a part of the quantized image data of FIG. 5 (A). For example,
FIG. 5B shows the (3 * 3) matrix portion at the upper left corner of FIG. 5A, and FIG. 5D shows the lower left corner of FIG. 5A. FIG. 5 (G) shows a (3 * 3) matrix portion in the lowermost part in the center of FIG. 5 (A), and FIG. 5 (I) shows a (3 * 3) matrix part in the central part on the right side in FIG. 5 (A). I have.

With respect to the quantized image data of FIGS. 5B to 5J, one vertical pixel from FIGS. 5B to 5J is used.
While shifting one horizontal pixel at a time, the twelve (3 *
The detection pattern is compared with the detection pattern including the matrix of the pixel size of 3). At this time, FIGS. 5 (B), (C), (E),
As shown in the matrix part of FIG. 3F, even a single pixel in the matrix of the pixel size of (3 * 3) to be compared is shown in FIG.
In the case where the halftone pixel pattern shown in (G) is included, the process proceeds to detection with the next matrix portion without performing comparison with the twelve types of detection patterns in FIG. That is, FIG.
The image data of (D), (G), (H) to (J) are collated with the detection pattern of FIG.
The center pixel of (3 * 3) is replaced with the smoothed pixel patterns of FIGS.

FIG. 6 shows a state in which the center of the matrix is smoothed after matching is detected with 12 types of detection patterns consisting of a (3 * 3) pixel size matrix for detecting a smoothed portion in FIG. FIG. 4 is an explanatory diagram showing a pattern to be replaced with a pixel.

The matrix portion shown in FIG. 5D and the matrix portion shown in FIG.
When the coincidence of the detection patterns of 2) is detected, the central part of the (3 * 3) matrix is replaced with the quantized pixel pattern of FIG. 3A and the smoothed pixel pattern of FIG. As shown in FIG. 6B-2, the process proceeds to detection of the next matrix portion.

The matrix portion shown in FIG. 5G and the matrix portion shown in FIG.
When the coincidence of the detection patterns of 1) is detected, the central part of the (3 * 3) matrix is replaced with the quantized pixel pattern of FIG. 3A and the smoothed pixel pattern of FIG. As shown in FIG. 6 (B-1), the process proceeds to detection of the next matrix portion. A match between the matrix portion of FIG. 5H and the detection pattern of FIG. 4 is not detected.

Moving on to the detection of the next matrix portion, FIG.
When the coincidence between the matrix part of (I) and the detection pattern of FIG. 4C-1 is detected, the center part of the matrix of (3 * 3) is converted from the quantized pixel pattern of FIG.
FIG. 6 is replaced with the smoothed pixel pattern of FIG.
As in (C-1), the process proceeds to the detection of the next matrix portion. Matching between the matrix portion of FIG. 5 (J) and the detection pattern of FIG. 4 is not detected.

FIG. 7 is an explanatory view for explaining an image obtained by smoothing the image quantized to eight values in FIG. 5 according to the first embodiment of the present invention.

The image shown in FIG. 7 is obtained by replacing the patterns shown in FIGS. 6 (B-2), 6 (B-1), and 6 (C-1), which have been replaced by detecting the coincidence as described above. Pixel is (5 * 5)
At the positions (2, 4), (3, 4) and (4, 3) in the matrix of FIG. From FIG. 7, 300 *
300 dpi image data of 600 * 6 which is double resolution
It can be seen that the interpolation of the pixels as the image equivalent to 00 dpi has been performed and the outline has been corrected. The pixel to be interpolated is
Upper and lower detection patterns consisting of a (3 * 3) matrix,
This corresponds to the position of (2, 2) excluding the left and right ends, and is the (3 * 3) pixel of the (5 * 5) pixels in the image of FIG.

In this embodiment, the pixel information obtained by combining the quantized pixel data and the smoothed pixel data is represented by 4 bits, but may be represented by a multi-bit number such as 6 bits or 8 bits. OK, and the matrix of one pixel is (4 *
Other than 2) may be used.

According to the present embodiment, interpolation pixel data (smoothed pixel data) is obtained by performing the above control.
Is provided, a cost increase and a reduction in processing speed due to an increase in memory capacity due to an increase in memory capacity are prevented, and multi-gradation input image data is quantized into three or more values, so that a plurality of dots having different landing positions for one pixel are formed. Provides a recording device that achieves high image quality by using the dot matrix recording method, by expressing half-tones using the image and improving gradation characteristics, and by correcting the outline of the image and suppressing the jaggedness of the image. can do.

(Second Embodiment) By the way, the printing ratio of a general document is approximately 4 to 5 of the recording pixel area of the recording medium.
%, And the printing ratio of halftone images such as photographs is about 2
It is about 0%. The pixels to be smoothed in the printing ratio are some pixels forming outlines of characters and the like, and the portion to be smoothed in the entire recording area is only a very small area. Therefore, in the present embodiment, an area that is not to be smoothed is primarily detected, and smoothing is not performed on this area, so that one pixel can be expressed more efficiently using a plurality of dots at different landing positions. Thus, control is performed to achieve both improvement in gradation and correction of the outline of an image to suppress the jaggedness of the image.

Also in the present embodiment, description will be made using the pixel pattern of FIG. 3, the detection pattern of FIG. 4, and the pattern of FIG.

As in the first embodiment, first, the input image data of multiple gradations is quantized into eight-level (level) data to form a pixel pattern shown in FIGS. 3A to 3H. To quantized image data.

FIG. 8 is an explanatory diagram for explaining an image in which multi-gradation input image data is quantized into eight values according to the first embodiment of the present invention.

With respect to the quantized image data of the (7 * 7) pixel matrix of FIG. 8, one vertical matrix from the upper left (3 * 3) pixel matrix to the lower right (3 * 3) pixel matrix is obtained. While shifting the pixel and the horizontal one pixel at a time, 12 in FIG.
Before detecting a smoothed portion by comparing with a detection pattern composed of a matrix of (3 * 3) pixel sizes, primary detection described below is performed.

FIG. 9 shows a pattern for primary detection of the presence or absence of the outline of an image according to the second embodiment of the present invention. In the present embodiment, in the step of detecting a smoothed portion, the pattern is used to primarily detect the presence or absence of an outline of a character or the like in the matrix of the detection pattern, thereby significantly improving the efficiency of the detection step. is there.

In the pattern of FIG. 9A, the matrix of (3 * 3) pixels is entirely a pixel pattern without dots of FIG. 3A, and the pattern of FIG. All the matrices are composed of the pixel patterns shown in FIG.

First, giving priority to the collation of the pattern having no dot shown in FIG. 9A, the quantized image shown in FIG.
Matching is performed while shifting one pixel at a time in the horizontal direction, and then the pattern of FIG. 9B is similarly compared with the quantized image of FIG. 8 to perform primary detection. Then, when a match is detected, primary detection is performed for the next matrix without performing comparison with the detection pattern of FIG. By primary detection with the pattern of FIG. 9 (A), 3D surrounded by a thick frame shown in FIGS. 10 (A) to 10 (C).
A match is detected in the area, and the area surrounded by the thick frame shown in FIG. 10D is detected by primary detection with the pattern in FIG. 9B. Since these areas have no dots or all dots and do not include outlines of characters and the like, no comparison with the detection pattern of FIG. 4 is performed.

If the patterns do not match in the primary detection, then the matrixes shown in FIGS.
The presence / absence of a halftone pixel pattern shown in (G) is detected, and if there is a halftone pixel pattern, the process proceeds to the primary detection with the next matrix unit without performing comparison with the twelve types of detection patterns in FIG.

If there is no halftone pixel pattern, a smoothed portion is detected, and the quantized image data is compared with the twelve types of detected patterns in FIG. 4 as in the first embodiment. As in the first embodiment, when a match is detected, the center pixel of (3 * 3) is replaced with the smoothed pixel patterns of FIGS. Thus, FIG.
In the image quantized to eight values, a region that does not include an outline is primarily detected, and another region that is not primarily detected is subjected to the first detection.
When the same smoothing as in the embodiment is performed, a smoothed double-resolution image shown in FIG. 11 is obtained.

The primary detection is performed by the above-described control, and when the coincidence is detected, the collation with the detection pattern shown in FIG. 4 is not performed. (Smoothed pixel data)
Is provided, a cost increase and a reduction in processing speed due to an increase in memory capacity due to an increase in memory capacity are prevented, and multi-gradation input image data is quantized into three or more values, so that a plurality of dots having different landing positions for one pixel are formed. To achieve high-quality images at high speed with the dot matrix recording method, because it is possible to express halftones using, and to improve the gradation characteristics, and to correct the outline of the image and suppress the jaggedness. An apparatus can be provided.

(Third Embodiment) In the present embodiment,
An example will be described in which image data to be smoothed in color multi-tone image data has a specific restriction. That is, as this restriction, the image data to be smoothed is limited to only black characters. Normally, 6 points (2 mm) to 24 points (8 mm) are mainly used for black characters, and even large characters are up to about 72 points (24 mm). In the present embodiment, black character extraction is performed by detecting a null raster having no data.

FIG. 12 shows a flowchart of a black character detection and printing method setting sequence.

First, the print data quantized in step S1 is read and temporarily stored in a memory such as the RAM 202. The memory can store black, yellow, magenta, and cyan independently, but the capacity of the memory depends on the size of characters to be extracted. For example, 7
If extracting up to 2 points, 400 at 300 dpi
It is necessary to store more than raster data, and when considering the A4 vertical size, it is about 176 kbytes per color. A memory having a capacity several times the maximum length that can be printed in one scan according to the number of nozzles of the recording head is preferable. The larger the capacity,
The identifiable black characters become larger. The mainstream of black characters is 24 points or less, and discrimination is possible with a capacity of about 136 rasters at 300 dpi.

In step S2, it is counted whether each color data exists in the raster. This is because a bit is set before or after each raster to determine whether or not there is data for each color data in the raster. This makes it possible to determine whether the data existing in the raster is black, color, or mixed.

In step S3, it is detected whether or not there is a null raster. If there is no null raster, it is determined that the data is continuous data in which images are connected, and the flow advances to step S6 to set a graphic printing method. This sequence is for detecting a black character to be smoothed, and this graphic printing method does not perform smoothing.

If there is a null raster, step S4
Detects if there is a next null raster. Here, if there is no next null raster, the determination cannot be made within the determined range, so that the process proceeds to step S6 to set the graphic printing method.

If there is a next null raster, the flow advances to step S5 to determine whether there is color data between the detected null rasters. If there is color data, it is regarded as not text, and a graphic printing method is set in step S6.

If there is no color data, it is regarded as a black character, and the flow advances to step S7 to set a text printing method and perform printing by smoothing according to the first or second embodiment.

When the graphic printing method or the text printing method is set, the flow advances to step S8 to determine whether or not there is print data. If there is print data, the process returns to step S1, and the sequence of black character detection and printing method setting is repeated again. If there is no print data, this sequence is terminated.

As described above, black character extraction is performed by detecting the presence or absence of a null raster, and image data determined to be black characters, that is, black text, is smoothed.
By setting a graphic printing method for other image data, black text can be recorded with high quality. Further, since the time required for performing the smoothing depends on the amount of existing black data, the processing time for performing the smoothing can be greatly reduced by limiting the image data to be smoothed. Was.

The present invention is not limited to the embodiments described with reference to the drawings.

[0075]

As described above, according to the present invention, multi-gradation image data is quantized, converted into a quantized pixel pattern, and a smoothed portion of the quantized image is detected. When the contour of the quantized image is corrected by interpolating the pixel of the detected smoothed portion, the pixel pattern for smoothing stored in the storage unit is replaced with the quantized pixel of the smoothed portion of the quantized image. Interpolation is performed by exchanging patterns, so that it prevents cost increase and processing speed reduction due to increase in memory capacity, expresses many halftones to improve gradation, and further outlines images and the like. There is a feature that correction can be performed to suppress the jaggedness.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a main part of a first embodiment of an inkjet recording apparatus to which the present invention has been applied.

FIG. 2 is a block diagram illustrating a configuration of a control circuit included in an inkjet recording apparatus to which the present invention has been applied.

FIG. 3 is an explanatory diagram illustrating a quantized pixel pattern and a pixel pattern to be smoothed according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a detection pattern for detecting a smoothed portion according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating an image in which multi-gradation input image data is quantized into eight values according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining a pattern in which a central portion of a matrix is replaced with a smoothed pixel pattern after detecting a match with the detection pattern of FIG. 4;

FIG. 7 is an explanatory diagram illustrating an image obtained by smoothing the image quantized to eight values in FIG. 5 according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating an image in which multi-gradation input image data is quantized into eight values according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating a pattern for primary detection of the presence or absence of an outline of an image according to the second embodiment of the present invention.

10 is an explanatory diagram illustrating an area where the image data in FIG. 8 and the primary detection pattern in FIG. 9 match.

FIG. 11 is an explanatory diagram illustrating an image obtained by smoothing an image quantized to eight values in FIG. 8 according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing a sequence for setting a black character detection and printing method performed in the third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 inkjet unit 12 guide shaft 13 carriage 14 drive belt 15 carriage motor 16 cap unit 17 paper discharge roller 200 CPU (central processing unit) 201 ROM 202 RAM 203 image input unit 304 image signal processing unit 205 main bus line 206 operating unit 207 recovery System control unit 208 Recovery system motor 209 Blade 210 Cap 211 Pump 212 Thermistor 213 Recording head 213a Heating element 214 Head temperature control circuit 215 Head drive control circuit

Claims (17)

[Claims] A quantizing step of quantizing the multi-gradation image data and converting it into a quantized pixel pattern; a detecting step of detecting a smoothed portion of the image obtained by the quantization; Correcting the contour of the quantized image by interpolating the pixels of the smoothed portion, wherein in the correcting step, the quantized image of the smoothed portion of the quantized image is quantized. An image recording method, wherein a pixel pattern is replaced with a pixel pattern for smoothing stored in a storage unit. 2. The quantized image is composed of a quantized pixel pattern, and the quantized pixel pattern and the smoothing pixel pattern are stored as 4-bit pixel information. 2. The image recording method according to claim 1, wherein the pattern comprises a (4 * 2) matrix. 3. In the detecting step, (n * m)
(M, n are positive integers of 3 or more) of the above-mentioned quantized images, a part of an image consisting of a matrix of (N * M) smaller than (n * m) and a matrix of (N * M) 2. The image recording method according to claim 1, wherein the smoothed portion is detected by collating with a detection pattern. 4. The image recording method according to claim 3, wherein when the partial image includes a halftone, the comparison with the detection pattern is not performed. 5. The method according to claim 1, wherein the horizontal direction of the detection pattern is 2 to (n).
The image recording method according to claim 3, wherein a pixel at a (-1) th position and a (m-1) th position in a vertical direction is set as an interpolation target. 6. The detecting step includes: firstly detecting a region not including an outline in the quantized image, and performing matching with the detection pattern for a region different from the region not including the outline. The image recording method according to claim 3, wherein: 7. The image recording method according to claim 6, wherein the primary detection is performed with priority given to matching of a pattern having no dots with a part of the quantized image. 8. A quantization step of quantizing multi-gradation image data and converting the image data into a quantized pixel pattern; a black detection step of detecting a black character portion from an image obtained by the quantization; An image recording method, comprising: a detecting step of detecting a smoothed portion of the quantized image when detected; and a correcting step of interpolating the detected pixel of the smoothed portion to correct the contour of the quantized image. Wherein the correcting step replaces the quantized pixel pattern at the smoothed portion of the quantized image with a smoothing pixel pattern stored in a storage unit. . 9. Quantizing means for quantizing multi-gradation image data and converting it into a quantized pixel pattern; detecting means for detecting a smoothed portion of an image obtained by quantization; Correction means for interpolating the pixel of the smoothed portion and correcting the contour of the quantized image, wherein the correction means performs the quantization of the smoothed portion of the quantized image. An image recording apparatus, wherein the pixel pattern obtained is replaced with a pixel pattern for smoothing stored in a storage unit. 10. The quantized image is composed of a quantized pixel pattern, and the quantized pixel pattern and the smoothing pixel pattern are stored as 4-bit pixel information. 10. The image recording apparatus according to claim 9, wherein the pattern is constituted by a (4 * 2) matrix. 11. The (N * M) matrix smaller than (n * m) among the (n * m) matrices (m and n are positive integers of 3 or more) by the detection means. The image recording apparatus according to claim 9, wherein the smoothed portion is detected by collating a part of the image composed of the following with a detection pattern of an (N * M) matrix. 12. The image recording apparatus according to claim 11, wherein when the partial image includes a halftone, the comparison with the detection pattern is not performed. 13. The method according to claim 11, wherein a pixel at a position of 2 to (n-1) th in a horizontal direction and a pixel of 2 to (m-1) th in a vertical direction of the detection pattern is to be interpolated. The image recording apparatus as described in the above. 14. The method according to claim 1, wherein the detecting means firstly detects a region not including the contour in the quantized image, and performs a comparison with the detection pattern for a region different from the region not including the contour. The image recording apparatus according to claim 11, wherein: 15. The image recording apparatus according to claim 14, wherein the primary detection is performed with priority given to matching of a pattern having no dots with a part of the quantized image. 16. A quantization means for quantizing multi-gradation image data and converting it into a quantized pixel pattern; a black detection means for detecting a black character part from the image obtained by the quantization; An image recording apparatus comprising: detecting means for detecting a smoothed portion of the quantized image when detected; and correcting means for correcting the contour of the quantized image by interpolating the detected pixel of the smoothed portion. The apparatus according to claim 1, wherein the correction unit replaces the quantized pixel pattern at the smoothed portion of the quantized image with a pixel pattern for smoothing stored in a storage unit. apparatus. 17. The image recording apparatus according to claim 9, wherein recording is performed using an inkjet recording head that ejects ink by thermal energy.