JPH1095141A - Image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain image quality by preserving only the true edge parts of an image even when a recording agent was saved by a method in which each picture element constituting a binary image is made an attention picture element, and a prescribed peripheral picture element range is divided into picture elements by a pattern table and converted into a high resolution binary image. SOLUTION: A binary image input into an image recording apparatus 1 is processed by a smoothing process part 2 and composed of a pattern matching part 3 and a resolution conversion part 4. In the pattern matching part 3, a binary image to be input is made an attention picture element, its peripheral picture elements are pattern-matching-processed with a pattern from a pattern table 5. The attention picture element is converted into four picture elements enlarged twice in length and breadth to be made high resolution and smoothing- processed. A reference pattern for cutting a picture element is added to a pattern table 5b for saving toner. In this way, although the smoothness of length and breadth lines is similar to ordinary smoothing, the number of black picture elements is reduced remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for converting an input binary image into a high-resolution binary image and recording the converted image. The present invention relates to an image recording apparatus that performs image recording in at least two image recording modes including a recording agent saving mode in which black pixels included in the high-resolution binary image are thinned out and recorded.

[0002]

2. Description of the Related Art In recent years, an electrophotographic method has been widely used as an image recording method for an image recording apparatus such as a facsimile machine, a digital copying machine, and a printer. In the electrophotographic method, generally, image recording is performed by transferring a toner image formed on a photoconductor corresponding to each black pixel included in an image to be recorded onto recording paper.

In recent years, as an image recording method for an image recording apparatus, in addition to the above-described electrophotographic recording method, an ink jet method has become widespread. In the ink jet system, image recording is generally performed by ejecting ink from nozzles and attaching the ink to recording paper corresponding to each black pixel included in an image to be recorded.

In such an electrophotographic or ink-jet type image recording apparatus, a certain amount of toner or ink is consumed per black pixel. Therefore, as the number of black pixels included in an image to be recorded is larger, a larger amount of recording agent such as toner and ink is consumed.

[0005] These toners and inks are consumables supplied in the form of toner cartridges, ink cartridges and the like. The consumption of toner and ink directly affects the running cost of the image recording apparatus. User interest in the reduction is great.

Therefore, in order to reduce the running cost, black pixels in an image to be recorded are thinned out (converted to white pixels) and recorded in a toner (ink) save mode, an economy mode, or the like. An image recording apparatus capable of reducing the consumption of a recording agent such as toner or ink by reducing the number of black pixels in a to-be-imaged image has been put into practical use (see, for example, Japanese Patent Application Laid-Open Publication No. Printer device ").

However, the conventional black pixel thinning process is a simple thinning process in which adjacent black pixels are thinned out every other pixel. Therefore, characters, line drawings, and the like composed of thin lines are blurred or blurred. , Its intelligibility (readability) tends to decrease. Therefore, at the time of the thinning process of black pixels, black pixels constituting an edge portion of an image, that is, black pixels adjacent to white pixels are not subjected to the thinning process, so that outlines of characters, line drawings, and the like are saved, There is an image processing apparatus that can maintain the intelligibility of thin lines such as characters and line drawings even when black pixels are thinned out.

However, it is effective to perform the thinning process of black pixels while preserving the black pixels constituting the edge portion of the image when applying to an image composed of characters, line drawings, and the like. However, it is not necessarily effective when the original halftone image is applied to a pseudo halftone image obtained by error diffusion processing or dither processing.

In other words, since the pseudo halftone image is an image obtained by converting the grayscale value of the original halftone image into the density of black pixels, a simple black pixel thinning process does not depend on the density of black pixels. , A certain percentage of black pixels are converted to white pixels,
The gradation is preserved. However, when a black pixel thinning process is performed on a pseudo halftone image while preserving black pixels constituting an edge portion of the image, it is determined whether a specific black pixel constitutes an edge portion of the image. Is performed simply on the condition that the specific black pixel is adjacent to the white pixel or not. Therefore, the high density portion in the original halftone image, that is, the density of the black pixel is high (the density of the white pixel is low). ) Portion or a low density portion in the original halftone image, that is, a portion where the density of black pixels is low (the density of white pixels is high), the density of black pixels is medium (the density of white pixels is also medium). There are fewer opportunities for black pixels and white pixels to be adjacent to each other (opportunities for the black pixels to be determined as pixels forming an edge portion).

Therefore, when a black pixel thinning process is performed on a pseudo halftone image while preserving black pixels constituting an edge portion of the image, a portion having a medium density of black pixels is obtained.
The thinning ratio of the black pixels is different between a portion where the density of the black pixels is high (or low), and a problem occurs that the gradation of the original halftone image is largely lost.

The problem of the thinning process of the black pixels while preserving the black pixels forming the edge portion of the image described above will be specifically described below with reference to the drawings.

FIG. 13 shows a thinning process for a relatively coarse image pattern, and FIG. 14 shows a thinning process for an extremely small character (number "2") image. In both figures, (a) shows the original image before the thinning processing. (B) shows an image obtained by simply thinning out the original image of (a) by 50%. (C)
FIG. 5A shows an image obtained by viewing the original image in the horizontal direction (main scanning direction) and simply thinning out the pixels by 50% while preserving black pixels (edge pixels) constituting edges. (D) shows an image obtained by viewing the original image of (a) in the horizontal direction (main scanning direction) and simply thinning out the pixels by 25% while preserving black pixels (edge pixels) constituting edges.

Here, 50% simple thinning is performed as shown in FIG.
Alternatively, a black pixel constituting the original image in FIG. 14A is set to a pixel value 1 and a white pixel is set to a pixel value 0, and 2 pixels in the main scanning direction.
As shown in FIG. 15A, the pixel value of the upper left and lower right pixels is 1 and the pixel value of the upper right and lower left pixels is 2 × 2 as shown in FIG. This is performed by comparing with the thinning pattern of the matrix. That is, the original image is compared with the 2 × 2 matrix shown in FIG. 15A for each four pixels, and the product of the pixel values of the corresponding pixels is calculated (1 ×
1 = 1, 1 × 0 = 0, 0 × 1 = 0, 0 × 0 = 0), and the operation result is set as a new pixel value of the pixel. Thus, for example, even if all four pixels in the original image are black pixels (pixel value 1), the result of taking the product with the 2 × 2 matrix shown in FIG. The pixel value of the pixel is 1, the pixel values of the upper right and lower left pixels are 0, and two of the four black pixels are converted to white pixels (thinned out).
Will be.

The same applies to 25% simple thinning.
3 (a) or a pixel value of 1 and a white pixel value of 0 in the original image of FIG. 14 (a), and a total of 2 pixels in the main scanning direction × 2 pixels in the sub-scanning direction (vertical direction) As shown in FIG. 15B, the pixel value of only the upper left pixel is 1 and the pixel values of the other pixels are 0 in units of 4 pixels.
This is performed by comparing with the thinning pattern of the matrix. That is, the original image is divided into 2 × 2 pixels shown in FIG.
Compare with the matrix and calculate the product of the pixel values of the corresponding pixels (1 × 1 = 1, 1 × 0 = 0, 0 × 1 = 0, 0 × 0 =
0), and the calculation result is set as a new pixel value of the pixel. Thus, for example, even if all four pixels in the original image are black pixels (pixel value 1), 2 × 2 pixels shown in FIG.
As a result of the product of the matrix and the matrix, the pixel value of only the upper left pixel is 1, the pixel values of the other pixels are 0, and three of the four black pixels are converted to white pixels (thinned out). )

The edge pixels are stored in a case where each pixel constituting the original image shown in FIG. 13A or FIG. 14A is set as a target pixel X, and the target pixel X is a black pixel (pixel value 1). The pixel adjacent to the target pixel X in the main scanning direction has a pixel value of 0 as shown in FIG.
In the case of (white pixels), even if the pixel of interest X is collated with the 2 × 2 matrix shown in FIG. 15A or 15B and determined to be a black pixel to be thinned out, This is done by not thinning out (saving).

13 (a) to 13 (d). Since the original image of FIG. 13 (a) is a relatively simple image pattern, FIG.
The discriminability of the original image is relatively easily preserved not only in the case of simple thinning out while preserving the edge pixels of FIGS. 3 (c) and 3 (d) but also in the case of simple thinning out in FIG. 13 (b).

On the other hand, the original image shown in FIG. 14A is an extremely small character image, and thus, when the simple thinning shown in FIG. 14B is performed, the discrimination of the original image is significantly deteriorated. However, in the case where the simple thinning-out is performed while the edge pixels shown in FIGS. 14C and 14D are preserved, deterioration of the discriminability of the original image can be prevented.

As described above, it can be seen that the thinning process in which edge pixels are preserved is effective for thin lines such as characters and line drawings.

Next, when the original image of the pseudo halftone image pattern obtained by converting the original 16-tone halftone image by the dither matrix shown in FIG. 50% simple thinning while performing edge thinning and 25% simple thinning while preserving edge pixels.

FIGS. 17 (a) through 17 (h) show, in order, an original halftone image having a plurality of densities (shading values of 2, 4, 6, and 5).
8, 10, 12, 14, and 16) are converted by the dither matrix shown in FIG. 16 and show a pseudo halftone image pattern as an original image. FIG. 17 (a) to (h)
As can be seen from the 4 × 4 pixel pattern (total number of pixels 16), each 4 × 4 pixel pattern includes black pixels proportional to the grayscale value of the original halftone image.

FIGS. 18A to 18H respectively show:
Each of the 4 × 4 pixel patterns shown in FIGS.
FIG. 13B shows a simple thinning-out of 50% under the same conditions as FIG. 13B or FIG. 14B.

FIGS. 19A to 19H respectively show:
Each of the 4 × 4 pixel patterns shown in FIGS.
FIG. 13C illustrates a case where the edge pixels are preserved under the same conditions as those of FIG. 13C or FIG.

FIGS. 20 (a) to 20 (h) respectively show
Each of the 4 × 4 pixel patterns shown in FIGS.
FIG. 13D shows a case where edge pixels are stored and 25% simple thinning is performed under the same conditions as those in FIG. 13D or FIG. 14D.

In each of the thinning processes shown in FIGS. 18 to 20, the processes are performed on the assumption that the pixel patterns shown in FIG. 17 are also repeated in the surroundings.

(A) in FIGS. 17 to 20 described above.
The vertical axis represents the image density converted by the number (density) of black pixels included in the pixel patterns of (h) to (h), and the respective densities of the original image shown in FIGS. FIG. 21 shows a result of plotting the image density converted by the number (density) of black pixels included in the pixel pattern corresponding to the original image density on the horizontal axis as the original image density.

As shown in FIG. 21, when the original image before thinning shown in FIG. 17 plotted by square points is used as a recorded image, the original image shown in FIG. 17 is naturally proportional to the image density. . The 5 shown in FIG. 18 plotted with diamond points
The recording density of the 0% simple thinned-out image is exactly half that of the original image density, and the gradation is preserved though the density is reduced.

However, in the case where the edge pixels shown in FIG. 19 plotted with circular points are saved and simple thinning is performed by 50%, the recording density is not exactly half the original image density, and the original image density is not reduced. In the medium density region, the pixels to be thinned out are stored too much as edge pixels, and the gradation is not preserved. The case where the edge pixels shown in FIG. 20 plotted by triangular points are saved and simple thinning is performed by 25% is more serious, and the recording density is not exactly half that of the original image density.
In the medium density area of the original image, the pixels to be thinned out are stored too much as edge pixels, the gradation is not preserved, and in the high density area in the original image, the pixels to be thinned out are stored. Is not maintained to the extent that is stored as an edge pixel, and gradation inversion occurs.

[0028]

As described above,
In the related art, when a simple thinning process is performed on an image to be printed in order to reduce the consumption of a recording agent such as toner or ink, the legibility of characters and line drawings of the recorded image is extremely reduced. Resulting in.

If the thinning process is performed on the image to be recorded while preserving the edge pixels, the legibility of the recorded characters and line drawings is improved, but the image to be recorded is a pseudo halftone image. In the case or when a pseudo halftone image portion is included, there is a problem in that the gradation of the recorded image is lost and the image quality is degraded.

In a conventional image recording apparatus, for example, as shown in FIG. 22, each pixel constituting a binary image having a resolution of 200 dpi inputted from a scanner 100 or the like is regarded as a pixel of interest. Is input to the pattern matching unit 3 of the smoothing processing unit 2 together with its peripheral pixels, and the pattern matching unit 3 performs pattern matching processing on the peripheral pixels of the target pixel with the normal smoothing pattern table of the pattern table 5. Some are divided into 2 × 2 pixels and converted into a high-resolution binary image of 400 dpi by the resolution converter 4 to improve the recording image quality.

When the toner save is ON, the high-resolution binary image is displayed at 400 dpi resolution by the electrophotographic method when the toner save ON is performed by the switch S1 which is switched by a toner save ON / OFF signal input from an external operation panel or the like. Is output as it is as a binary image to be recorded on the plotter 7 for recording, and in the case of the toner save OFF, it is inputted to the thinning-out processing section 6 and the above-described thinning-out processing is performed. Plotter 7 as an image
Is output to

However, even in this case, the resolution conversion processing in the smoothing processing section 2 and the thinning processing in the thinning processing section 6 are independent of each other. Remains.

The present invention has been made in view of the above circumstances, and when an input binary image is converted into a high-resolution binary image and recorded, image recording that saves a recording agent such as toner and ink is performed. It is an object of the present invention to provide an image recording apparatus capable of storing only a true edge portion of an image and performing image recording while maintaining image quality, regardless of the content of an image to be recorded.

[0034]

According to a first aspect of the present invention, there is provided an image recording apparatus for converting an input binary image into a high-resolution binary image and recording the high-resolution binary image. In an image recording apparatus that performs image recording in at least two image recording modes, a normal mode in which a value image is recorded as it is and a recording agent saving mode in which black pixels included in the high-resolution binary image are thinned out and recorded. And at least two types of pattern tables, a pattern table for high-resolution processing and a pattern table for recording agent saving processing for performing high-resolution while shaving black pixels constituting an edge portion of the image. Sometimes, the normal high resolution processing pattern table is output, and in the printing material saving mode, the printing material saving processing pattern table is output. A turntable generating unit, and performing a pattern matching process using a pattern table output from the pattern table generating unit, wherein each pixel constituting the input binary image is set as a target pixel, and a predetermined peripheral pixel range of the target pixel is subjected to pattern matching processing. Resolution conversion means for converting the input binary image into a high-resolution binary image to be recorded by dividing the pixel of interest into a plurality of pixels.

According to a second aspect of the present invention, there is provided an image recording apparatus.
In the image recording apparatus described above, each pixel constituting the input binary image is set as a target pixel, the target pixel is divided into a plurality of pixels, and a thinning process is performed by a predetermined thinning pattern to obtain a high-resolution thinning 2 Resolution conversion thinning-out processing means for outputting as a value image, and high resolution 2 from the resolution conversion means in the recording material saving mode.
The value image and the high-resolution thinned-out binary image from the resolution conversion thinning-out processing means are converted from the pixels constituting the high-resolution binary image by the pixels which are the source of the pixels. For the pixels that have been matched in the pattern matching process with the pattern table for the printing material saving process, the high resolution binary image is prioritized, and for the other pixels, the high resolution thinned binary image is prioritized and synthesized. Image synthesizing means for outputting as a high-resolution binary image to be recorded.

The image recording apparatus according to the third aspect is the first aspect of the invention.
In the image recording apparatus described above, the pattern table generating unit includes, as the recording material saving processing pattern table, a plurality of printing material saving processing pattern tables having different degrees of shaving black pixels forming an edge portion of an image. Pattern table switching means for switching and selecting any one of the plurality of printing material saving processing pattern tables as a printing material saving processing pattern table to be output.

According to the image recording apparatus of the present invention, there is provided an image recording apparatus comprising:
In the image recording apparatus described above, the resolution conversion thinning processing means includes a plurality of thinning patterns having different thinning rates as a predetermined thinning pattern used in the thinning processing, and the pattern table generating means includes the printing material saving method. As a processing pattern table, a plurality of printing material saving processing pattern tables having different degrees of shaving black pixels constituting an edge portion of an image are provided, while a plurality of thinning patterns and a plurality of printing material saving processing pattern tables are provided. A thinning pattern / pattern table switching means for switching and selecting any one of them as a thinning pattern to be used in the thinning processing or a pattern table for a recording material saving processing to be output is further provided. .

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the accompanying drawings by dividing into first, second and third embodiments. In each of the embodiments described below, image data that has been binarized at a resolution of 200 dpi is converted to a high-resolution image of 400 dpi, which is twice as long and wide.
A description will be given of a case where the image is converted into a value image and recorded and output by a plotter of a 400 dpi electrophotographic recording method. However, the present invention is not limited to this and can be similarly applied to other resolutions.

FIG. 1 shows a block configuration of an image recording apparatus 1 according to the first embodiment of the present invention.

As shown in FIG.
A binary image is input from the scanner 100 having a reading resolution of 0 dpi (corresponding to a case where the copying machine includes the image recording apparatus 1). The binary image input to the image recording apparatus 1 may be a binary image received from a partner apparatus via a communication line (corresponding to a case where the facsimile apparatus includes the image recording apparatus 1) or a personal computer. Or a binary image transferred from a higher-level device (equivalent to a case where the printer device includes the image recording device 1). In short, a binary image having a resolution of 200 dpi may be input.

The binary image input to the image recording device 1 is
The processing is performed by the smoothing processing unit 2. The smoothing processing unit 2 includes a pattern matching unit 3 and a resolution conversion unit 4
It is composed of The pattern matching unit 3 sets each pixel constituting the input binary image as a target pixel,
The peripheral pixels are subjected to pattern matching processing with the pattern from the pattern table 5, and the pixel of interest is converted into four pixels, which is twice as long and wide, thereby increasing the resolution and performing smoothing processing. The resolution conversion unit 4 includes the pattern matching unit 3
Creates a binary image of 400 dpi from the four pixels converted from each pixel constituting the input binary image,
The image is output to a 400 dpi electrophotographic plotter 7 as a binary image to be recorded. Plotter 7 in that case
Is substantially proportional to the number of black pixels included in the binary image output from the smoothing processing unit 2.

In the conventional resolution enhancement of a binary image with a smoothing process, each pixel constituting an input image is set as a pixel of interest, a peripheral pixel is referred to, and a pattern which smooths a predetermined oblique line is used. As shown in FIG. 2, the input image having a slope of 1 is optimally stored and the edges are smoothed by the pattern matching process, as shown in FIG. The same applies to the case where the inclination is 1/2 and the case where the inclination is 1/3.

As described above, the conventional resolution enhancement of a binary image with a smoothing process literally focuses only on the smoothing process of an input image, and cannot cope with toner saving.

Therefore, in the first embodiment, the pattern table 5 referred to by the pattern
And two pattern tables, a normal smoothing pattern table 5a and a toner saving pattern table 5b, as in the prior art, and a toner save ON input by pressing a switch on an operation panel (not shown) or the like. Switch S that switches according to the / OFF signal
2, the output is switched to the pattern matching unit 3. That is, when the toner save ON / OFF signal is ON, the switch S2 is switched to the toner save pattern table 5b, and the toner save ON is performed.
When the / OFF signal is OFF, the switch S2 switches to the normal smoothing pattern table 5a side.

FIGS. 3 and 4 show examples of processing in the smoothing processing unit 2 when an inclined image is input to the image recording apparatus 1 according to the first embodiment.

In the case of FIG. 3, the input tilt image has a tilt of 1, and when the pattern matching unit 3 performs the pattern matching process on the input image, when the toner save mode is OFF, the reference image is used as a reference pattern. A reference pattern for normal smoothing is referred to. This reference pattern is a pattern of 5 × 3 pixels, and a pixel position surrounded by a bold frame at the center corresponds to the position of the target pixel. In addition, a plain pixel in the reference pattern is a white pixel, a hatched pixel is a black pixel, and a pixel with a cross is a pixel that may be either a white pixel or a black pixel. Is shown.

When the toner save mode is ON, the reference pattern in the case of the toner save smoothing is referred to as a reference pattern.

When each pixel constituting the input inclined image is set as a target pixel, and a 5 × 3 peripheral pixel including the target pixel matches the reference pattern, the target pixel becomes
According to the division pattern shown in the figure, the image is divided into four 2 × 2 pixels and output as an image after smoothing processing.

In the case of FIG. 4, the input tilt image has a tilt of 、. When the pattern matching unit 3 performs the pattern matching process on the input image, when the toner save mode is OFF, the reference pattern is used. , Two types of reference patterns in the case of normal smoothing are referred to.

When the toner save is ON, the reference pattern in the case of the toner save smoothing is referred to as the reference pattern.

When each pixel constituting the input inclined image is set as a target pixel, and a 5 × 3 peripheral pixel including the target pixel matches the reference pattern, the target pixel is defined as
According to the division pattern shown in the figure, the image is divided into four 2 × 2 pixels and output as an image after smoothing processing.

As is clear from FIGS. 3 and 4, in the case of normal smoothing and the case of toner saving smoothing, the smoothness of the smoothed image is the same, but the number of black pixels is small. However, it can be seen that the amount is smaller in the case of the toner saving smoothing.

In FIG. 5, in the image recording apparatus 1 according to the first embodiment, each of the oblique lines having the inclinations of 1, 1/2, and 1/3 is used as an input image, when the normal smoothing processing is performed, and The result when the save is smoothed is shown. The numbers at the upper left of each column indicate the number of pixels when the size of one pixel at the resolution after the smoothing process is set to one.

As can be seen from the figure, the normal smoothing process preserves the number of black pixels constituting the original input oblique line image almost as it is, while the toner saving smoothing process does not Even though the smoothness is about the same as normal smoothing, the number of black pixels is much smaller than the number of black pixels constituting the original input oblique line image.

As described above, by using the toner saving smoothing pattern, the number of black pixels after the smoothing process is reduced, and the amount of toner consumed by the plotter 7 can be saved. Further, in the normal smoothing process, only the pattern matching process is performed with reference to only a reference pattern for the purpose of smoothing a step in a hatched portion and removing an uneven portion. 5b, a reference pattern for deleting pixels is added to the pixels at the edges of the vertical and horizontal lines as shown in FIG. As a result, as shown in FIG. 6, in the case of normal smoothing processing, the number of black pixels constituting the original input vertical / horizontal line image is also preserved as it is, as shown in FIG. In the case of the smoothing processing, the number of black pixels is much smaller than the number of black pixels constituting the original input vertical / horizontal line image, even though the smoothness of the vertical / horizontal lines is almost the same as that of normal smoothing. .

On the other hand, when a binary image in which a halftone image has been subjected to pseudo halftone processing is input, the input image has a pixel pattern as shown in FIG. 17, that is, black pixels and white pixels. Many periodically appearing patterns exist in an image. Therefore, as shown in FIG. 7, the pattern to be referred to in the pattern matching process is determined such that the white side is widely determined, and the edge of the halftone portion represented by the pseudo halftone in the input binary image is hardly detected. By doing so, the smoothing process is not performed on the halftone portion, and it is possible to prevent the side effect of destroying the gradation even if the pseudo halftone image is input.

Therefore, in the toner saving smoothing process, while the edges of characters and line drawings that should be preserved are preserved, toner can be saved by reducing the number of thinned black pixels. High resolution can be achieved without breaking the tonality.

Next, a second embodiment of the present invention will be described. FIG. 8 shows a block configuration of the image recording apparatus 1 according to the second embodiment. Of the configuration shown in FIG.
The only difference from the configuration of the image recording apparatus 1 according to the first embodiment shown in FIG. 1 is that a resolution conversion thinning-out unit 8 is provided and a combining unit 9 is provided. 1 are given the same reference numerals as in FIG. 1 and detailed description is omitted.

In FIG. 8, the input binary image is input to the smoothing processing unit 2 and, in parallel thereto, to the resolution conversion thinning processing unit 8.

In the resolution conversion thinning-out processing section 8, 200d
The resolution of each pixel of the input binary image of pi is converted into 400 dpi by doubling by converting the pixels into 2 × 2 pixels in the vertical and horizontal directions, and further, simple thinning processing is performed by the thinning pattern shown in FIG. The resolution-decimated binary image is input to the synthesizing unit 9.

FIG. 9 shows an output example of the oblique line image, the image after the resolution conversion, and the image after the thinning processing input to the resolution conversion thinning processing section 8. As shown in FIG.
The high-resolution thinned binary image (the image after the thinning process) input to (1) is not subjected to the smoothing process, and the binary image with the simply increased resolution is the simple thinned image at the thinning rate of 50%.

When the toner save is OFF, the synthesizing unit 9 outputs the high-resolution binary image input from the smoothing processing unit 2 to the plotter 7 as it is. An image obtained by synthesizing the high-resolution binary image to be recorded and the high-resolution binary image input from the resolution conversion thinning processing unit 8 is output to the plotter 7 as a high-resolution binary image to be recorded.

In the image synthesis in this case, among the pixels constituting the high-resolution binary image input from the smoothing processing unit 2, the pixels that are the source of those pixels are determined by the pattern table 5 in the pattern matching unit 3. For the pixels that have been matched in the pattern matching process with the toner saving pattern table 5b, the high-resolution binary image input from the smoothing processing unit 2 is given priority, and for the other pixels, the resolution conversion thinning process is performed. The high-resolution thinning-out binary image input from the section 8 is combined with priority.

FIGS. 10 and 11 show an example of the image synthesizing process in the synthesizing section 9. FIG. 10 shows a case where the input binary image is a diagonal line, and FIG. 11 shows a case where the input binary image is a solid black image.

As is apparent from FIG. 10, the hatched edge portion is output from the smoothing processing section 2 so that the black pixel of the edge is preserved, and the black pixel constituting the edge of the character / line image to be preserved is interposed. It is not drawn, and the rate of decrease in legibility is small.

On the other hand. As is apparent from FIG. 11, in the edge portion of the solid black image, the smoothing processing unit 2
The black pixels at the edges are preserved for output from. Since the black pixels in a solid black portion, such as a thick portion of a character other than an edge and having a small decrease in readability even when many black pixels are thinned out, are thinned by the resolution conversion thinning processing unit 8, the first embodiment described above is used. As compared with the image recording apparatus according to the above, the amount of toner consumption can be greatly reduced.

Next, a third embodiment of the present invention will be described. FIG. 12 shows a block configuration of an image recording apparatus 1 according to the third embodiment. The configuration shown in the figure differs from the configuration of the image recording apparatus 1 according to the second embodiment shown in FIG. 8 in that the toner save ON / OFF signal 2 is input to the resolution conversion thinning processing unit 8. And a point that a toner save pattern table 1 (5b) and a toner save pattern table 2 (5c) are provided instead of the toner save pattern table 5b of the pattern table 5, and a toner save is performed instead of the switch S2. ON / OFF
It is provided with a switch S3 that can be switched by the signal 1, and the other components are denoted by the same reference numerals as in FIG. 8 and detailed description is omitted.

In FIG. 12, the resolution conversion thinning-out processing section 8 adds a 50% simple thinning-out thinning pattern shown in FIG. 25% simple thinning thinning pattern shown in Fig. 7 and toner save ON / OFF
In response to signal 2, the two thinning patterns are switched. Thus, the thinning rate in the resolution conversion thinning processing unit 8 is set to 5 by the toner save ON / OFF signal 2.
It can be switched between 0% and 25%.

The toner save pattern table 1
(5b) and the toner save pattern table 2 (5
c) are pattern tables in which the degree of thinning, that is, the toner saving rate differs, and toner save ON is set.
By switching the switch S3 with the / OFF signal 1, the normal smoothing pattern table 5a is output to the pattern matching unit 3, or the toner save pattern table 1 (5b) or the toner save pattern table 2 (5c) Whether to output to the matching unit 3 can be selected.

Accordingly, a toner saving rate setting key corresponding to the toner save ON / OFF signals 1 and 2 is provided on an operation panel (not shown) for each toner saving rate (including a normal mode in which toner is not saved). By setting the toner saving rate and switching the thinning pattern referred to in the thinning processing in the resolution conversion thinning processing section 8 and the pattern table input as the reference pattern to the pattern matching section 3 according to the setting, the user It is possible to record an image with a balance between the desired image quality and the toner saving rate.

In each of the embodiments described above, the present invention is applied to an electrophotographic image recording apparatus using toner. However, the present invention is not limited to this. The present invention can be similarly applied to an image recording apparatus that consumes an amount of the recording material corresponding to the number of black pixels included in the image recording apparatus.

[0072]

According to the first aspect of the present invention, in the recording material saving mode, the resolution conversion means sets each pixel constituting the input binary image as a pixel of interest, and The predetermined surrounding pixel range is used as the pattern table to be referred to when performing the pattern matching process, and the pattern table for the printing material saving process is used. Therefore, in the printing material saving mode, the resolution increasing process in the normal mode is performed. In comparison, higher resolution processing is performed so as to reduce the number of black pixels constituting the edge portion of the image, and the consumption of the recording agent used when recording the high-resolution binary image can be reduced. In other words, in the recording material saving mode, the number of black pixels in the entire image is reduced by reducing a relatively large number of black pixels at the edge portion of the character / line image, thereby reducing the consumption of the recording material. In the character portion, the image is converted into an image in which the thickness of the character is reduced, so that the intelligibility of the character is less likely to be impaired than in a conventional simple thinning process. On the other hand, for the image portion subjected to the pseudo halftone recognition processing, by paying attention to the characteristic in which the white pixels and the black pixels constituting the pseudo halftone image are dispersed, a pattern matching pattern in which black pixels are not thinned out is set. Since the image portion subjected to the pseudo halftone process is not subjected to the thinning process, the halftone gradation is not lost. Thus, when performing image recording while saving the recording agent such as toner and ink, it is possible to record only the true edge portion of the image and maintain the image quality without depending on the content of the image to be recorded. . In addition, since it is possible to perform the recording agent saving process simply by adding a pattern table for saving the recording agent to the pattern table used in the normal high resolution processing, the image after the conventional resolution conversion is performed. By performing the thinning process, the circuit scale can be significantly reduced as compared with an image printing apparatus configured to perform the printing material saving process.

According to the second aspect of the present invention, the image synthesizing means preferentially leaves black pixels constituting edges of characters and line drawings to be stored in the high-resolution binary image from the resolution converting means. On the other hand, for the other pixels, the high resolution binary image from the resolution conversion thinning processing means is prioritized, and the high resolution binary image to be recorded is synthesized. Black pixels in a black solid image portion such as a portion or a thick portion of a character are thinned out by a thinning process using a predetermined thinning pattern, thereby further reducing the consumption of the recording material. In addition, since the thinning process is not a conventional thinning process with edge preservation but a thinning process in which black pixels can be thinned out at a fixed rate regardless of the image content, an image portion subjected to pseudo halftone processing is not processed. Uniform thinning processing can be performed, and there is no side effect such as grayscale inversion. On the other hand, regarding the character portion, since the thinning process is not performed on the thin characters, the resolution does not decrease. Although thinning processing is performed for thick characters, the intelligibility does not decrease because the edge portion is preserved.

According to the third aspect of the present invention, the pattern table switching means includes a plurality of recording material saving processing patterns provided in the pattern table generating means, each of which has a different degree of cutting black pixels constituting an edge portion of an image. Since any of the tables can be switched and selected as the pattern table for the recording material saving process to be output, the degree of saving of the recording material can be set in a plurality of stages, and the user can select a desired printing image. It is possible to flexibly cope with the balance between the image quality and the degree of toner saving.

According to the fourth aspect of the present invention, a plurality of printing material savings which differ in the degree to which black pixels constituting an edge portion of an image are provided by the pattern table generating means by the thinning pattern / pattern table switching means. Any one of the processing pattern tables can be switched and selected as a recording material saving processing pattern table to be output, and further, any one of a plurality of thinning patterns having different thinning rates provided in the resolution conversion thinning processing means. Can be switched and selected as a thinning pattern to be used in the thinning processing. Therefore, a plurality of recording material saving processing pattern tables that differ in the degree to which the black pixels forming the edge portions of those images are shaved are different from each other. Various combinations of multiple thinning patterns allow multiple levels of savings in printing material It is possible to set finely the floor, it is further possible to flexibly correspond to the balance of the degree of image quality and toner saving of the recorded image that the user desires.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a block configuration of an image recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a conventional process for increasing the resolution of a binary image with a smoothing process.

FIG. 3 is a diagram illustrating a processing example in a smoothing processing unit when an inclined image is input to the image recording apparatus according to the first embodiment.

FIG. 4 is a diagram illustrating an example of processing in a smoothing processing unit when an inclined image is input to the image recording apparatus according to the first embodiment together with FIG.

FIG. 5 is a diagram illustrating an image recording apparatus according to the first embodiment in which a normal smoothing process is performed using slanted images having inclinations of 1, 1/2, and 1/3 as input images;
FIG. 14 is a diagram illustrating a result when a smoothing process of toner save is performed.

FIG. 6 is a diagram illustrating results of a case where normal smoothing processing and a case where toner saving smoothing processing is performed using a vertical line / horizontal line image as an input image in the image recording apparatus according to the first embodiment.

FIG. 7 is referred to in a pattern matching process.
It is a figure showing a reference pattern which judges a white side widely.

FIG. 8 is a diagram illustrating a block configuration of an image recording apparatus according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an output example of an oblique line image, an image after resolution conversion, and an image after thinning processing input to the resolution conversion thinning processing unit of the image recording apparatus according to the second embodiment.

FIG. 10 is a diagram illustrating an example of an image combining process in a case where an input binary image is an oblique line in a combining unit of the image recording apparatus according to the second embodiment.

FIG. 11 is a diagram illustrating an example of an image synthesis process in a case where an input binary image is a solid black image in a synthesis unit of an image recording apparatus according to a second embodiment.

FIG. 12 is a diagram illustrating a block configuration of an image recording apparatus according to a third embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of a thinning process for a relatively simple image pattern.

FIG. 14 is a diagram illustrating an example of a thinning process for a relatively fine image pattern.

FIG. 15 is a diagram illustrating a pixel matrix referred to for a thinning process and an edge pixel storage process.

FIG. 16 is a diagram illustrating an example of a dither matrix.

17 is a diagram illustrating a pixel pattern as an original image obtained by performing a pseudo halftone process on a multi-valued image of each gray level using the dither matrix illustrated in FIG. 16;

18 is a diagram illustrating a pixel pattern that has been subjected to a 50% simple thinning process by comparing the original image illustrated in FIG. 17 with the pixel matrix illustrated in FIG.

FIGS. 19A and 19B show the original images shown in FIGS.
FIG. 13 is a diagram showing a pixel pattern subjected to a 50% thinning-out process while preserving edge pixels by being compared with the pixel matrix shown in FIG.

FIG. 20 shows the original image shown in FIG. 17 in FIGS.
FIG. 21 is a diagram showing a pixel pattern subjected to a 25% thinning-out process while preserving an edge pixel by being compared with the pixel matrix shown in FIG.

FIG. 21 is a diagram showing a preservation state of gradation by each processing before thinning (original image), 50% simple thinning, 50% thinning while preserving edge pixels, and 25% thinning while preserving edge pixels. It is a figure which shows the comparison of.

FIG. 22 is a diagram illustrating a configuration example of a conventional image recording apparatus that converts an input binary image into a high-resolution binary image and records the image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image recording apparatus 2 Smoothing processing part 3 Pattern matching part 4 Resolution conversion part 5 Pattern table 5a Normal smoothing pattern table 5b, 5c Toner save pattern table 6 Thinning-out processing part 7 Plotter 8 Resolution conversion thinning-out processing part 9 Synthesis part 100 Scanner S1, S2, S3 switch

Claims (4)

[Claims] 1. A normal mode in which an input binary image is converted into a high-resolution binary image and recorded, and a normal mode in which the high-resolution binary image is recorded as it is, and a black mode included in the high-resolution binary image In an image recording apparatus that performs image recording in at least two image recording modes, that is, a recording material saving mode in which pixels are thinned out, a pattern table for normal high resolution processing and black pixels constituting an edge portion of the image are cut off. And at least two types of pattern tables for a recording material saving process for performing high resolution while outputting the normal high resolution processing pattern table in the normal mode, and in the printing material saving mode in the normal mode. A pattern table generating unit that outputs the pattern table for the recording material saving process; and each pixel that forms the input binary image. As eye pixels, a predetermined peripheral pixel range of the target pixel by dividing the target pixel to a plurality of pixels by pattern matching process by the pattern table outputted from said pattern table generation means, is the input 2
An image recording apparatus comprising: a resolution conversion unit that converts a value image into a high-resolution binary image to be recorded. 2. A high-resolution thinned binary image, wherein each pixel constituting the input binary image is set as a target pixel, the target pixel is divided into a plurality of pixels, and a thinning process is performed using a predetermined thinning pattern. A high-resolution binary image from the resolution converting unit and a high-resolution binary image from the resolution converting unit in the recording material saving mode. Among the pixels constituting the resolution binary image, the pixels whose original pixels match in the pattern matching processing with the printing material saving processing pattern table in the resolution conversion means are the same as those described above. The high-resolution binary image is to be recorded with priority given to the high-resolution binary image, and the other pixels are to be synthesized and recorded with priority to the high-resolution thinned binary image. 2. The image recording apparatus according to claim 1, further comprising an image synthesizing unit that outputs a value image. 3. The printing apparatus according to claim 1, wherein the pattern table generating means includes a plurality of printing material saving processing pattern tables each having a different degree of shaving black pixels constituting an edge portion of an image as the printing material saving processing pattern table. 2. The image according to claim 1, further comprising a pattern table switching means for switching and selecting any one of the plurality of printing material saving processing pattern tables as a printing material saving processing pattern table to be output. Recording device. 4. The resolution conversion thinning processing means includes a plurality of thinning patterns having different thinning rates as predetermined thinning patterns used for the thinning processing, and the pattern table generating means includes a plurality of thinning patterns for the printing material saving processing. As the pattern table, a plurality of printing agent saving process pattern tables having different degrees of shaving black pixels constituting an edge portion of an image are provided, and each of the plurality of thinning patterns and the plurality of printing agent saving process pattern tables is provided. A thinning pattern / pattern table switching means for switching and selecting any one of them as a thinning pattern to be used in the thinning processing or as a printing material saving processing pattern table to be output. 2. The image recording apparatus according to 2.