JP2004001311A - Image processing device, recording device, image processing method, recording method, program, and storage medium - Google Patents

Abstract

An object of the present invention is to record a smooth image having no granularity, unevenness, or streaks from highlights to high density portions with multiple dots while maintaining high resolution based on a minimum dot.
When performing multi-dot printing, binarization is performed at a resolution based on a minimum dot, a dot set where n dots of a first size are set is extracted, and the extracted dot set is obtained. Is converted into a dot of a second size larger than the first size, and only a portion where the minimum dots are aggregated is replaced with a larger dot.
[Selection diagram] Fig. 3

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing device, a recording device, an image processing method, a program, and a storage medium, and more particularly to a pseudo halftone process for recording an image using dots of a plurality of sizes.
[0002]
[Prior art]
In a printing apparatus that prints an image by attaching ink to a printing medium, such as an ink jet system, two types (binary) of whether (1) or not (0) ink is applied to one print pixel. In general, the combination is expressed by density. On the other hand, the input image data has multi-level (multi-value) density information. Therefore, in the printing apparatus, a pseudo intermediate process of expressing the density of the area with the average density of a plurality of printing pixels is performed.
[0003]
An error diffusion method is known as one of the pseudo intermediate processing methods. The error diffusion method is described in, for example, "An Adaptive Algorithm for Spatial Gray Scale" in society for Information Display 1975 Symposium, Digest of Technology, and the description of the 19th, Technical Paper, 36.
[0004]
The error diffusion method will be briefly described below. Here, it is assumed that the pixel of interest is P, the density of the pixel is V, and the densities of the peripheral pixels P0, P1, P2, and P3 of P are V0, V1, V2, V3, and a threshold for binarization, respectively. The printing apparatus compares the multi-valued density value V of P with the threshold T for printing on the target pixel P, and performs printing such as ejecting ink if V is equal to or larger than T, and If it is smaller than T, no ejection is performed. At this time, the output binary data of P is represented by О, and the difference between the two is represented by a binarization error E.
If V ≧ T, O = 1, E = V−Vmax
If V <T, then O = 0 and E = V−Vmin.
(Vmax: maximum density, Vmin: minimum density)
The binarization error E is assigned to peripheral pixels after weighting P0 to P3 with weighting coefficients W0, W1, W2, and W3 empirically obtained. That is, assuming that the errors distributed to P0 to P3 are E0, E1, E2, and E3, E0 = E × W0, E1 = E × W1, E2 = E × W2, and E3 = E × W3. P0 to P3 are compared with a threshold value T by adding the above errors E0 to E3 to the densities V0 to V3 when the pixel itself becomes the target pixel. When the above processing is performed for each pixel, in an area including a certain number of pixels, the expressed output density and the average density of the input image are substantially equal.
[0005]
By the way, even if a certain gradation can be obtained by a pseudo halftone process such as an error diffusion method, another problem may be derived from the problem of graininess of a highlight portion. In other words, depending on the image to be recorded, even when a natural density change is obtained from the medium density portion to the high density portion, in the highlight portion, the dispersed dots are conspicuous and impair the smoothness of the entire image. There is. For this reason, in recent years, there has been a tendency to reduce the granularity of an image by recording with as small dots as possible.
[0006]
However, if all the dots are reduced to small dots, a new problem arises. One is the problem of landing accuracy on a recording medium. Small dots are more susceptible to misalignment on paper than large dots. In particular, from the middle density portion where the dots are arranged adjacently to the high density portion, the displacement of the dots is likely to be sensed as unevenness or streaks. Another problem is the effect on the life of the recording head. If all printing is performed with small dots, the number of ejections increases, and the life of the printing head is shortened accordingly.
[0007]
As one of the methods for solving the above problem, a so-called multi-dot recording in which a dot diameter to be recorded for one recording pixel is adjusted in a plurality of steps by using a recording head capable of ejecting ink droplets having different sizes. There is something to do. According to this multi-dot recording, the above problem can be solved because the highlight portion where the graininess is a problem can be recorded with small dots, and the medium and high density portions where the unevenness and streaks are a problem can be recorded with large dots. can do. In this case, since the above-mentioned error diffusion method cannot be applied as it is, for example, as a pseudo intermediate processing method, Katoh, Y. et al. Arai, Y .; According to Yasuda "multi-level error diffusion method" (Nationa1 Conerence of Communication, Department in Showa53 Year, Society of Electronic Communication, Department in Showa53 Year, Society of Electronic Communication in Japan (1973), pp 504 (Japanese)) is applied Often. In the above-described error diffusion method, multi-value density data is converted into binary data by using a threshold value T which is one fixed value. However, in this multi-level error diffusion method, a plurality of thresholds (T1 to Tn) are provided and converted into n + 1-level density data. Then, the recording apparatus performs recording with a dot diameter of a size corresponding to each threshold value.
[0008]
As described above, in recent printing apparatuses, density data is quantized into a plurality of stages by pseudo halftone processing such as a multi-valued error diffusion method, and the output data is handled by a plurality of stages of dot diameters. This reduces problems such as unevenness, streaks, and graininess in highlights, and achieves high image quality close to that of a photograph without impairing the life of the head.
[0009]
[Problems to be solved by the invention]
However, in the multi-dot recording method of recording dots of different sizes, the recording resolution is lower than in the method of recording only small dots. In other words, in multi-dot recording, although the number of gradations that can be expressed by one pixel increases, the resolution of one pixel is reduced to about the size of the maximum dot. Conversely, in the printing method using only small dots, although the number of gradations per pixel decreases, high resolution printing is possible because the size of one pixel is equivalent to one small dot.
[0010]
Such a difference in resolution appears in the character quality, the fine line, and the sharpness of the figure. Therefore, even in the multi-dot recording method capable of resolving unevenness, streaks, and the graininess of a highlight portion, there is a defect that the resolution is still inferior to that of the recording method using only small dots.
[0011]
The present invention has been made to solve the above-described problems, and an object of the present invention is to maintain a high resolution based on a minimum dot, and to improve dot resolution from a highlight portion to a high density portion. An object of the present invention is to provide an image processing apparatus, a recording apparatus image processing method, a recording method, a program, and a storage medium capable of recording a smooth image with sufficiently reduced graininess, unevenness, and streaks.
[0012]
[Means for Solving the Problems]
Therefore, according to the present invention, in an image processing apparatus that creates image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium, multi-valued image data corresponding to an image to be recorded is stored in the image processing apparatus. Binarization processing means for binarizing, and, in the binary image data obtained by the binarization processing means, a dot set location where n dots of a first size are set (n is a natural number of 2 or more) is extracted. And a dot converting means for converting the dot collection points extracted by the dot extracting means into dots of a second size larger than the first size.
[0013]
In another embodiment, in an image processing apparatus for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium, multi-valued image data corresponding to an image to be recorded is converted into binary data. Binarization processing means for converting, and, in the binary image data obtained by the binarization processing means, a dot set point where n dots of the first size (n is a natural number of 2 or more) are extracted. Dot extraction means, dot conversion means for converting the dot collection location into dots of a second size larger than the first size, and a predetermined area for the binary image data obtained by the binarization means. Matrix arrangement means for arranging a matrix having a predetermined dot conversion priority within the matrix, and the binary image data in the matrix arranged by the matrix arrangement means. A conversion ratio calculating unit that calculates a ratio of performing dot conversion in the matrix, the conversion ratio calculated by the conversion ratio calculating unit, and the dot conversion priority in the matrix, wherein the matrix is arranged. Dot conversion determining means for determining a dot collection location to be converted among the dot collection locations in the predetermined area, wherein the dot conversion means determines the dot collection location determined by the dot conversion determination means. It is characterized by performing dot conversion.
[0014]
Further, in an image processing method for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium, binarizing multi-valued image data corresponding to an image to be recorded. A binarization processing step, and a dot extraction step of extracting a dot collection point where n dots of the first size are aggregated (n is a natural number of 2 or more) in the binary image data obtained in the binarization processing step And a dot conversion step of converting the dot collection points extracted in the dot extraction step into dots of a second size larger than the first size.
[0015]
In another aspect, in an image processing method for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium, multi-valued image data corresponding to an image to be recorded is converted into binary data. Binarization step of performing a binarization process, and extraction for extracting a dot collection point where n dots of the first size are aggregated (n is a natural number of 2 or more) in the binary image data obtained in the binarization step And a step of arranging a matrix having a predetermined dot conversion priority in a predetermined area on the binary image data obtained in the binarization step. Based on the calculated conversion ratio and the dot conversion priority, based on the calculated conversion ratio and the dot conversion priority. A determining step of determining a dot collection point to be converted among the dot collection points in the predetermined area; and converting the determined dot collection point into a dot of a second size larger than the first size. And a dot conversion step.
[0016]
According to the above configuration, when performing multi-dot recording, binarization is performed at a resolution based on the minimum dot, and a portion where the minimum dots are collected is replaced with a larger dot. While maintaining the high resolution, it is possible to record a smooth image from the highlight portion to the high density portion, in which graininess, unevenness, streaks, and the like are sufficiently reduced.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 8 is a perspective view for explaining a schematic configuration of a recording apparatus used in one embodiment of the present invention. The recording device 50 of this example is a recording device of a serial scan system, and a carriage 53 is guided by guide shafts 51 and 52 so as to be movable in a main scanning direction indicated by an arrow A. The carriage 53 is reciprocated in the main scanning direction by a driving force transmission mechanism such as a carriage motor and a belt for transmitting the driving force. The recording head 10 (not shown in FIG. 8) and an ink tank 54 for supplying ink to the recording head 10 are mounted on the carriage 53. The recording head 10 and the ink tank 54 may constitute an ink jet cartridge. After the paper P as a recording medium is inserted from an insertion port 55 provided at the front end of the apparatus, the transport direction is reversed, and then the paper P is transported by the feed roller 56 in the sub-scanning direction of arrow B. The recording device 50 performs a recording operation in which the recording head 10 is moved in the main scanning direction and ink is ejected toward the print area of the paper P on the platen 57, and the paper P is sub-scanned by a distance corresponding to the recording width. The image is sequentially recorded on the paper P by repeating the transport operation of transporting in the direction.
[0019]
A recovery system unit (recovery processing unit) 58 facing the formation surface of the ejection port of the recording head 10 mounted on the carriage 53 is provided at the left end in FIG. The recovery system unit 58 is provided with a cap capable of capping the ejection port of the recording head 10, a suction pump capable of introducing a negative pressure into the cap, and the like. In this manner, the ink is sucked and discharged from the discharge port 15 and a recovery process is performed to maintain a good ink discharge state of the recording head 10. In addition, by ejecting ink that does not contribute to the image from the ejection port toward the inside of the cap, a recovery process can be performed to maintain a good ink ejection state of the recording head 10.
[0020]
FIG. 9 is a plan view of the recording head 10 as viewed from the ink ejection port side. In the recording head 10 of the present embodiment, three sizes of ejection ports are provided in order to eject ink droplets having different sizes to achieve large, medium, and small dot diameters. Reference numeral 11 denotes a discharge port for small dots, reference numeral 12 denotes a discharge port for medium dots, and reference numeral 13 denotes a discharge port for large dots. As shown in the figure, the ejection port 12 for medium dots is based on a position shifted by a half pitch with respect to the ejection port 11 for small dots, and the arrangement pitch is twice as large as that for small dots. Similarly, the ejection opening 13 for large dots is based on a position shifted by a half pitch from the ejection opening 12 for medium dots, and the arrangement pitch is twice as large as that for medium dots. The arrow A indicates the same direction as in FIG. 8 and corresponds to the moving direction of the carriage 54. The ink for image recording is supplied from an ink supply unit (not shown) into a flow path leading to each of the ejection ports, and forms a meniscus at the ejection ports 11 to 13. Each of the flow passages is provided with a heating element (electric heat conversion element). By generating heat energy from the heating element, the ink in the flow passage is heated and foamed by film boiling. Large, medium, and small ink droplets are ejected from each ejection port by the foaming energy at that time.
[0021]
(Embodiment 1)
FIG. 1 is a schematic block diagram of an image processing apparatus according to the first embodiment of the present invention. More specifically, FIG. 1 shows an image processing circuit configured in the recording apparatus shown in FIG. Note that the image processing device shown in the figure may be configured in an information processing device such as a personal computer, and the present invention naturally includes such a configuration.
[0022]
In FIG. 1, 101 is an output value data generator for determining data to be output according to input data, 102 is a comparator, 103 is a selector, 104 is a storage error buffer for storing error data, and 105 is stored This is a divider that distributes the sum of error data to peripheral pixels. The above 101 to 105 are for performing the binary error diffusion processing described in the related art, and in the present embodiment, first, the multi-valued image signal In is converted into the multi-valued image signal In by using these. The output signal is converted into a binary output signal Out on the assumption that all of the data is printed with small dots.
[0023]
First, an error dIn generated by the error diffusion processing is added to the multi-valued original image data In. The output value data generator 101 performs a binarization process based on the added input value and the threshold T, and outputs a value of 1 or 0 (255 or 0) as an Out signal (output signal). The comparator 102 compares the output value (Out) with a value (In + dIn) obtained by adding an error to the input multi-valued image data. The selector 103 calculates the difference between them (In + dIn−Out), and accumulates this value in the accumulation error buffer 104 as error data. The accumulated data is distributed in the divider 105 according to a predetermined distribution coefficient, and this value is newly added as dIn to the input multi-valued image data of the corresponding peripheral pixel.
[0024]
Reference numerals 106 and 107 are processing unique to the present embodiment. Reference numeral 106 denotes a medium dot conversion unit that replaces small dots with medium dots, and reference numeral 107 denotes a large dot conversion unit that replaces medium dots with large dots. The state of each conversion process will be described with reference to FIGS.
[0025]
FIG. 2 is a diagram showing a conversion relationship from small dots to medium dots and from medium dots to large dots. In the present embodiment, the arrangement conditions of the respective dots are determined so that the density values before and after the conversion become the same. In this case, the small dots are arranged in a state of 2 × 4 = 2 × 4. The four small dots are converted to one medium dot, and when the medium dots are arranged in a state of 2 × 2 = 4, the four medium dots are converted to one large dot. It is supposed to.
[0026]
FIG. 3 shows an image when recording is performed by the recording head 10 shown in FIG. 8 according to the conversion described in FIG. As shown in FIG. 3A, the image data output from the selector 103 is composed of only binary values of small dots. In this figure, black circles indicate recording pixels, and white circles indicate non-recording pixels. For this image data, the medium dot conversion unit 106 sequentially determines small dot groups that satisfy the conversion rule shown in FIG. 2A, and replaces them with medium dots. If recording is performed at this stage, the state shown in FIG. In the present embodiment, the medium dot group satisfying the conversion rule shown in FIG. 2B is sequentially determined by the large dot conversion unit 107 and replaced with a large dot. As described above, the image shown in FIG. 3A, which is initially composed only of small dots, is finally composed of a mixture of small dots, medium dots, and large dots as shown in FIG. 3C. Become.
[0027]
According to the present embodiment, only the places where small dots are arranged adjacent to each other are replaced with larger dots in accordance with the rules shown in FIG. Therefore, by recording medium dots and large dots, the resolution does not decrease and the resolution composed of small dots is preserved, so that the sharpness of characters and figures is not lost. On the other hand, when the method of recording the output value of the multi-level error diffusion described in the conventional method with multi-dots is applied to the above-described recording apparatus, the original input pixel has a large dot size, that is, a small dot of 16 pixels. That is, one minute is defined as one pixel. Therefore, the resolution is lower and the sharpness of characters and graphics is inferior to that of the present embodiment.
As described above, according to the present embodiment, after generating binary data in a high-resolution state based on small dots (dots of the first size), a predetermined number of adjacent small dots are generated. Is extracted from the binary image data, and this dot collection point is converted into a larger dot (a dot of a second size larger than the first size). By performing multi-dot printing, the advantage of multi-dot printing (which can reduce unevenness and streaks in middle and high density areas sufficiently and the life of the print head is long), while recording with only the minimum dots High-resolution recording equivalent to that of.
[0028]
(Embodiment 2)
Hereinafter, a second embodiment will be described with reference to the drawings. Also in the present embodiment, the inkjet recording apparatus having the configuration described with reference to FIGS. 8 and 9 is applied.
[0029]
FIG. 4 is a schematic block diagram related to the image processing unit of the present embodiment. In FIG. 4, reference numerals 101 to 105 are for performing binary error diffusion processing, and are the same as those described in FIG. 1 of the first embodiment. Therefore, the value Out output from the selector 103 is a binary signal assuming that printing is performed with small dots. In 401 and 402, processing unique to the present embodiment is performed. 401 is a medium dot conversion matrix for replacing small dots with medium dots, and 402 is a large dot conversion matrix for replacing mixed data of medium and small dots with large dots. is there.
[0030]
6 and 7 are diagrams illustrating a conversion method performed by the medium dot conversion matrix 401. FIG. FIG. 6 shows an example of a medium dot conversion matrix, which is composed of a grid of 4 × 4 = 16 pixels of medium dots. In the present embodiment, as in the first embodiment, 2 × 2 = 4 small dots are converted into one medium dot. Therefore, each of the 16 grids has 2 × 2 = 4 small dots. Each one is supported. The numbers 1 to 16 shown in each grid indicate the priority of converting small dots in each grid into medium dots, and the numbers are distributed. Also in the present embodiment, the medium dot is replaced when four small dots are collected, but further conditions are added when performing the conversion. The condition is whether or not the order arranged in the matrix is allowed to be converted. Which order is allowed is determined by the conversion rate, which is calculated from the average of the original image data in the matrix.
[0031]
FIG. 7A is an example of an image composed of only small dots. The matrix of interest is shown by a solid grid. In this matrix, 52 pixels out of a total of 64 pixels are filled with small dots. Therefore, the average density in this matrix is 52/64 = 13/16. Although this average density may be used as the conversion rate as it is, in the function of the present embodiment, 12/16 is used as the conversion rate, and the portion corresponding to 1 to 12 among the numbers 1 to 16 shown in FIG. The position can be converted to. Then, a portion where all four small dots are present in the grids from 1 to 12 is converted into a medium dot. FIG. 7B shows the state after the conversion. As can be seen from the figure, even if there are four small dots, there are places where they are not converted to medium dots depending on the value of the conversion rate.
[0032]
FIG. 5 is a flowchart when the above conversion process is performed. First, in step 501, binary error diffusion processing based on small dots is performed on multi-valued original image data. Next, in step 502, the average value of the original data in the 4 × 4 pixel matrix is calculated. In the case of FIG. 7A, it is 52/64. Further, in step 503, the conversion rate in the matrix is calculated using the calculated average value. In the case of FIG. 7A, it is 12/16. The function for calculating the conversion rate from the average value does not necessarily have to be in a proportional relationship. The bright part of the image, that is, the part where the density of small dots is low (the average value of the original data is low) is not converted as much as possible, and the dark part of the image, that is, the density of the small dots is high (the average value of the original data is low). The object of the present invention can be more positively achieved by setting the (high) portion as a function that increases the conversion rate to medium dots.
[0033]
In step 504, a position in the matrix to be converted into a medium dot is determined based on the conversion rate determined in step 503. In FIG. 6, 1 to 12 correspond to the determined positions.
[0034]
Steps 505 to 508 show a process of sequentially performing conversion on each pixel in the matrix. First, in step 505, it is determined whether the processing for conversion has been completed for all 16 pixels. If it has been completed, the conversion process of the matrix of interest ends, and the process moves to the next matrix. If not, the process proceeds to step 506. In step 506, it is determined whether or not the pixel of interest satisfies the condition for conversion to a medium dot. More specifically, it is determined whether the position corresponds to the conversion position determined in step 504 and whether all four small dots are present. If the conversion condition is not satisfied, the process proceeds to step 507 without converting to a medium dot, and the conversion position of interest is moved. If the conversion condition is satisfied, the data is converted into medium dots in step 508.
[0035]
The method of converting small dots to medium dots has been described above. In the present embodiment, as shown at 402 in FIG. 4, the output data is further converted to large dots. For the conversion of the large dot, the same processing as the algorithm described above is performed with the small dot as the medium dot and the medium dot as the large dot. At this time, a function for calculating the size and conversion rate of the matrix may be provided independently of the medium dot conversion matrix.
[0036]
By performing the above-described series of processes on all image data, an image can be finally formed with three stages of large, medium, and small dot sizes.
[0037]
As described above, according to the present embodiment, after generating binary data on the basis of small dots, a predetermined pattern in which a plurality of small dots are adjacent to each other (a dot collection location where n small dots are collected) Is extracted from the image data, and when the extracted position (dot collection point) is allowed to be converted by the conversion rate in the matrix, the dot is converted into a larger dot to perform multi-dot recording. As a result, similar to the first embodiment, high-resolution printing equivalent to printing with only the minimum dots could be performed while taking advantage of the advantages unique to multi-dot printing.
[0038]
Further, according to the present embodiment, the degree of conversion can be suitably moved by adjusting the function for obtaining the conversion rate from the average density. Therefore, it is possible to prolong the life of the head by not using small dots on the high-density side while more emphasizing the resolution of the low-medium-density portion than in the first embodiment.
[0039]
Further, in a matrix having a certain degree of spread, medium dots and large dots after the actual conversion are appropriately dispersed, and it is possible to eliminate the connection of dots peculiar to error diffusion.
[0040]
The conversion order shown in the above-mentioned medium (large) dot conversion matrix is not limited to the illustrated order, and may be changed every time the medium (large) dot conversion matrix is applied. The size of the medium (large) dot conversion matrix is not limited to 4 × 4, but may be, for example, 4 × 2, 8 × 8, or the like.
[0041]
(Other embodiments)
In the first and second embodiments, the 2 × 2 rectangular small dot (medium dot) group is converted into the medium dot (large dot). However, this is not limited to the 2 × 2 rectangle. , 4 × 2, 4 × 4, etc., that is, a dot group of any shape is applicable. Also, only the case where all of the rectangles are filled with small dots (medium dots) is targeted for conversion. For example, if there are three or more dots in a 2 × 2 rectangle, a larger dot is used. You may make it convert.
[0042]
Further, by using the recording head of FIG. 9, the configuration is such that the middle dot (large dot) is replaced with the center of four small dots (medium dots), but the present invention is not limited to this. By changing the positional relationship and the number of the ejection openings in FIG. 9, various conversion methods can be performed. May be discharged. Further, a dot size larger than three stages of large, medium and small may be realized.
[0043]
Further, as another means for changing the discharge amount, the present invention is effective in a configuration in which an electrostrictive element such as a piezo element is arranged in each flow path and the discharge amount is adjusted by the shape of a voltage pulse applied to the electrostrictive element. It is.
[0044]
In addition, in the first and second embodiments, the dot conversion process is performed in order to form an image with dots of three types, that is, small dots, medium dots, and large dots. However, the present invention is not limited to this. Not something. For example, a dot conversion process may be performed in order to form an image using two types of dots, a small dot and a medium dot. Further, a dot conversion process may be performed to form an image with four or more types of dots. In short, dot conversion processing may be performed so as to form an image with at least two types of dots including a dot of a first size and a dot of a second size larger than the dot of the first size. It is.
[0045]
Further, in the above embodiment, the error diffusion method has been described as an example of the binarizing means assuming small dots, but the present invention is not limited to this. There are other means such as a dither method in the pseudo halftone processing, and the present invention is applicable to any pseudo halftone processing.
[0046]
The present invention is not limited to the above-described embodiment in which the dot conversion process of the image data is performed on the inkjet recording apparatus side, but may be performed on a host computer or the like connected to the inkjet recording apparatus.
[0047]
In addition, even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), a device including one device (for example, a copier, a facsimile device, and the like) May be applied.
An object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the storage medium in the storage medium. Needless to say, this can also be achieved by reading and executing the program code thus read.
[0048]
In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. The program itself also constitutes the present invention.
[0049]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0050]
When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. Does part of or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0051]
Further, after the program code read from the storage medium is written into the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, the function expansion board is written based on the instruction of the program code. It goes without saying that a CPU or the like provided in the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0052]
【The invention's effect】
As described above, according to the present invention, when performing multi-dot recording, binarization is performed at a resolution based on the minimum dot, and a portion where the minimum dots are collected is replaced with a larger dot. As a result, it is possible to sufficiently suppress unevenness and streaks at high densities and maintain the same high resolution as when recording with only the minimum dots, while taking advantage of the unique advantages of multi-dot recording that the recording head has a long life. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of an image processing unit according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between multi-dot sizes.
FIG. 3 is an explanatory diagram of dot conversion according to the first embodiment of the present invention.
FIG. 4 is a schematic block diagram of an image processing unit according to a second embodiment of the present invention.
FIG. 5 is a dot conversion flowchart according to the second embodiment of the present invention.
FIG. 6 is a dot conversion matrix according to the second embodiment of the present invention.
FIG. 7 is an explanatory diagram of dot conversion according to the second embodiment of the present invention.
FIG. 8 is a perspective view of an ink jet recording apparatus applied in the embodiment of the present invention.
FIG. 9 is a schematic diagram of an ink jet recording head applied in an embodiment of the present invention.
[Explanation of symbols]
10 Recording head
11 Small dot ejection port
12 Medium dot ejection port
13 Large dot ejection port
50 Recording device
51 Guide shaft
52 Guide shaft
53 carriage
54 ink tank
55 insertion slot
56 feed roller
57 Platen
58 Recovery unit
101 Output value data
102 comparator
103 Selector
104 Accumulation error buffer
105 divider
106 Medium dot conversion unit
107 Large dot converter
401 Medium dot conversion matrix
402 Large dot conversion matrix

Claims (9)

In an image processing apparatus that creates image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
Binarization processing means for binarizing multi-valued image data corresponding to an image to be recorded;
Dot extraction means for extracting a dot set point where n dots of the first size (n is a natural number of 2 or more) are set in the binary image data obtained by the binarization processing means;
Dot conversion means for converting the dot collection points extracted by the dot extraction means into dots of a second size larger than the first size;
An image processing apparatus comprising: In an image processing apparatus that creates image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
Binarization processing means for binarizing multi-valued image data corresponding to an image to be recorded;
Dot extraction means for extracting a dot set point where n dots of the first size are set (n is a natural number of 2 or more) in the binary image data obtained by the binarization processing means;
Dot conversion means for converting the dot collection location into dots of a second size larger than the first size;
Matrix arranging means for arranging a matrix having a predetermined dot conversion priority within a predetermined area on the binary image data obtained by the binarizing means;
A conversion ratio calculating unit that calculates a ratio of performing dot conversion in the matrix from the binary image data in the matrix arranged by the matrix arranging unit;
Based on the conversion ratio calculated by the conversion ratio calculation means and the dot conversion priority in the matrix, the dots to be converted among the dot collection points in the predetermined area where the matrix is arranged Dot conversion determining means for determining the gathering location,
The image processing apparatus according to claim 1, wherein the dot conversion unit performs dot conversion on a dot set point determined by the dot conversion determination unit. The image processing apparatus according to claim 1, wherein the binarizing unit is an error diffusion method. A recording apparatus for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
An image processing apparatus according to claim 1,
And a dot recording unit for recording dots of the first and second sizes obtained by the dot conversion unit in the image processing apparatus on the recording medium. In an image processing method for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
A binarization processing step of binarizing multi-valued image data corresponding to an image to be recorded;
A dot extraction step of extracting a dot aggregation point where n dots of the first size are aggregated (n is a natural number of 2 or more) in the binary image data obtained in the binarization processing step;
A dot conversion step of converting the dot collection points extracted in the dot extraction step into dots of a second size larger than the first size;
An image processing method comprising: In an image processing method for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
A binarizing step of binarizing multi-valued image data corresponding to an image to be recorded;
An extraction step of extracting, from the binary image data obtained in the binarization step, a dot set where n dots of the first size are set (n is a natural number of 2 or more);
Arranging a matrix having a predetermined dot conversion priority within a predetermined area on the binary image data obtained in the binarization step;
A conversion ratio calculation unit that calculates a ratio of performing dot conversion in the matrix from the binary image data in the arranged matrix;
A determination step of determining a dot aggregation location to be converted among the dot aggregation locations in the predetermined area where the matrix is arranged, based on the calculated conversion ratio and the dot conversion priority,
A dot conversion step of converting the determined dot collection location into a dot of a second size larger than the first size. A recording method for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
An image processing method according to claim 5 or 6,
A dot recording step of recording, on the recording medium, dots of the first and second sizes obtained by the dot conversion step in the image processing method. A program that causes a computer to execute an image processing method for creating image data for recording an image composed of dots of a plurality of sizes having different recording areas on a recording medium,
Program code for a binarization processing step of binarizing multi-valued image data corresponding to an image to be recorded;
A program code of a dot extraction step of extracting a dot set point where n dots of the first size are set (n is a natural number of 2 or more) in the binary image data obtained by the binarization processing step;
A program, comprising: a program code of a dot conversion step of converting a dot set extracted in the dot extraction step into a dot of a second size larger than the first size. A storage medium storing a computer-readable program,
A storage medium storing the program according to claim 8.

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