JPH04197765A - Image processing device - Google Patents

Abstract

PURPOSE:To make images formed in accordance with characteristics of image formation elements by a method wherein data are developed into multivalued image data, and the multivalued image data are processed by binary coding and are stored after modulation is applied to said multivalued data, and the stored data are made available for transferring to an image formation means. CONSTITUTION:PDL data supplied from a host computer are developed into multivalued image data with a PDL interpreter program, and are made in the form expressed in multivalued density. The said density can be expressed in a formula DATA1(x, y). In the case of the title device, pixels (x, y) are printed with a nozzle on the (y mod 128)th position. Therefore the multivalued image data DATA1(x, y) are corrected as shown in a formula DATA2=DATA 1(x, y)/f(y mod 128). The correction is made by increasing in advance the data to be printed with nozzles in which average density is low. As the image data in this processing are multivalued ones, fine correction can be made. Then binary coding of the multivalued data is made in the process E by dither method with reference made to dither patterns stored in a ROM 5 for the dither a binary image data memory 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus for forming an image by binarizing a multivalued image.

[Prior art] Data in a page description language, that is, PDL (Page Disclosure Language), from a computer, etc.
A printer configured as shown in FIG. 9 can be considered as a printer that receives multivalued image data and forms a binary image. As shown, from the host computer 112 to the interface 11 and external interface circuit 10
6, the PDL data and multilevel image data are temporarily stored in a buffer in the RAM 103, and then
According to the processing procedure stored in the ROM 102, the CPU
01 into binary image data and written into the binary image memory 107. 110 is a CPU bus.

On the other hand, the image forming section 10g is, for example, an electrophotographic black and white printer, and forms an image based on the image signal 153 read out from the binary image memory 107. The address generation unit 109 receives a synchronization signal 151 from the image forming unit 108.
Based on this, a read address (address signal 152) from the binary image memory 107 is generated.

Figure 10 shows the PDL sent from the host computer.
This figure shows a procedure in which the CP[J 101 develops data and multivalued image data into binary image data. first,
PDL data (a) is characters.

Since the graphical image is described in language, it is developed into multivalued image data (a). This expanded multi-value image data and the multi-value image data sent from the host computer are then converted into binary data for each pixel by binarization processing (1), resulting in binary image data. (o). As a method for this binarization, there are methods such as a dither method, an error diffusion method, and an average density preservation method.

[Problems to be Solved by the Invention] However, in the conventional example described above, if a method in which the output element has density variations, such as an inkjet method, is used as the image forming section, unevenness occurs once. there were.

FIG. 11A shows a schematic configuration of a print head 119 in an inkjet system. Ink supplied from the ink tank 123 is ejected from each nozzle 120 under the control of the ejection control unit 121 and printed on an output medium such as paper. In the case of this conventional example, the number of nozzles is 128, and ejection or non-ejection is controlled for each nozzle.

FIG. 11B shows a method of printing on paper 124 using this printing pad 119. As shown at 125, the print head 119 moves in the X direction (main scanning direction) of the paper 24 while moving in the Y direction (sub scanning direction).
Printing is performed with a width of 128 pixels. Next, as shown at 126, printing is performed in the same manner by moving 128 pixels in the Y direction.

FIG. 11C is a graphical example of the relationship between each nozzle of the print head 119 and the average density (relative value) of the ink ejected from the nozzle onto the paper. As shown in Figure 11c, the average density within a certain range may vary depending on the nozzle number due to variations in the discharge control unit, variations in temperature, variations in nozzle angle, etc. between each nozzle. There is. This variation is caused by changing the nozzle number to
When the average density (relative value) is d, it is expressed as the following equation (1). That is, d=f (rl)...(1
).

In this way, if there is density variation between nozzles, paper 1
Even if an attempt is made to print a uniform density on 24, as shown in FIG. 11D, density variations occur with a period of 128 pixels, degrading the image. This density variation becomes noticeable when the image has uniform density, but it also affects normal images.

As a method for correcting such density variations, a method of correcting density variations between nozzles for binarized data can be considered. Even if you try, since the data is binary (0 or 1), it will not be possible to perform corrections such as increasing the density by 110%.

On the other hand, if the developed multivalued image data is stored in a memory in a multivalued state and then read out and stored, it will be binarized with variation correction, the storage capacity of the memory will become enormous. , the cost of the equipment increases significantly.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and its purpose is to provide an image processing device that can form an image according to the characteristics of an image forming element and can save capacity. It is in the point of providing.

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the objectives, an image processing device according to the present invention includes a development means for developing data described in a page description language into multivalued image data. , a modulation means for modulating the multivalued image data developed by the development means, a binarization means for binarizing the multivalued image data modulated by the modulation means, and a binarization obtained by the binarization means. It is characterized by comprising a storage means for storing image data, and a transfer means for transmitting the binarized image data to an image forming means that performs image formation based on the binarized image data stored in the storage means. .

[Operation] According to this configuration, the expansion means expands the data described in the page description language into multivalued image data, the modulation means modulates the multivalued image data developed by the expansion means, and the binarization means Binarize the multivalued image data modulated by the modulation means,
The storage means stores the binarized image data obtained by the binarization means, and the transfer means transfers the binarized image data to the image forming means that forms an image based on the binarized image data stored in the storage means. do.

[Embodiments] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a block diagram showing a monochrome PDL compatible printer in a first embodiment of the present invention. In the same figure, 5
o indicates the printer of this embodiment, 1 indicates the CPU that controls the entire device, and 2 indicates the fourth CPU for operating CPUt.
RO that stores programs etc. that follow the flowchart in the figure.
3 indicates a RAM used as a work area for various programs. 4 is a font ROM, 5 is a dither pattern ROM, 6 is an external interface, 7 is a binary image memory, 8 is an image forming section, 9 is an address generation section, 11 is an interface, 10 GiCPU bus 51
52 indicates a synchronization signal, 52 indicates an address signal, and 53 indicates an image signal. 4 to 11 above. 51 to 53 correspond to 104 to 111 and 151 to 153 in FIG. 9, and because they are similar, , the explanation is omitted.

In particular, as a configuration different from the conventional one, there is an image forming element characteristic RAM indicated by 54, which is backed up by a battery, and which can be used to input numerical values manually through the operation section 55 or read a predetermined print pattern using a reading device (not shown). The dispersion characteristics between the image forming elements manually input by the user are stored.

trie L++-rm =---e +-w +-,
.

- data 12 to interface 11. PDL data (PDL commands) such as boss scripts sent via the external interface circuit 6 are stored in a buffer in the RAMB, and then developed into binary image data by the CPU and stored in the binary image memory 7. will be written to.

On the other hand, the image forming section 8 is a BJ, which is a type of inkjet method having the method and characteristics shown in FIGS. 11A to 11D.
It is a monochrome (bubble jet) type printer, and forms an image based on an image signal 53 read out from a binary image memory 7. The address generating section 9 generates a read address from the binary image memory 7 based on the synchronization signal from the image forming section 8.

FIG. 2 is a diagram showing a procedure in which CPU i develops PDL data sent from a host computer into binary image data. As an example of PDL data, Adobe
There is data written in the Post Script language proposed by e-company.

First, since the PDL data (A) supplied from the host computer is written in one character, one figure, and an image basket language, it is expanded into multivalued image data using the font data in the font ROM 5 using the PDL interpreter program. (B) As a result, each pixel is expressed as a multivalued density value (C), and the density value is expressed as DATA 1 ( It can be expressed by the equation (x, y).

Next, the multivalued image data is corrected for output element characteristics (D
). That is, assuming that the BJ method printer head used in this embodiment has the method and characteristics shown in FIGS. 11A to 11D, the density variation characteristic d=f(n) for each nozzle is corrected. . The variation characteristics can be determined by human input of numerical values or by a reading device (not shown).
The image forming element characteristic RAM 54 is input by reading the turn and has been updated since January.
i items are retained.

For each pixel (x + y), which nozzle prints that pixel can be uniquely determined by the coordinate value, and in the case of this example, the pixel (x, y) is (y mod 12
8) Printed with the th nozzle. m.

d is an operation to obtain the remainder. For this reason, the multivalued image data D A T A 1 (x, y) is expressed by the following equation (2).
Correct as shown below. That is, ...(2) becomes. In this way, data printed by nozzles with a low average density is corrected by increasing it in advance. Also, the image data at this time is multivalued (for example, 8b
In the case of it, it is expressed as O~255), so 110
Minor corrections such as percentage increases can be made.

Next, in (E), while referring to the dither pattern in the dither pattern ROM 5, (G) performs binarization using the dither method, and writes the result to the binary image data memory 7 (F).
.

If there is a plurality of PDL data, the above process is repeated for the number of commands. The binarized image data is sequentially overwritten, and a binary image is finally completed when all commands are expanded. By using such a PDL development method, the memory requirement can be significantly reduced.

FIG. 3 is a diagram showing an example of a dither matrix used in the first embodiment. For the dither method, -2
Since this is a value conversion method, it will not be described in detail, but as shown in FIG. 3, a multivalued image is converted into a binary image using each data of the dither pattern matrix TH (XX, yy) as a threshold value. That is, for corrected multivalued image data DATA2 (x, y), 2
The value image data DATA3 (x, y) is expressed by the following formula (3),
It is expressed as (4). That is, DATA2 (x, y) <published (x mad 8),
(ymad 8), DATA2 (x, y) 20 - (3) DATA2 (x,
y) ≧ publication (x mad &), (y mod 8)
If , DATA3(X,:y)=1
-(4).

To develop the above-described PDL data into binary image data, all the PDL data for one image forming area is stored in the buffer of RAM3, all of it is converted to multi-value image data, and then the binary image data is Perform transformations on data. In this way, all PD
By sequentially expanding L data after supplying it from the host computer to the RAM 3, the host computer can be opened at an early stage. That is, here 1
Data for a screen is processed as one image forming part.

Note that in order to save the buffer memory of the RAM 3, each PDL data may be transferred and expanded from the host computer. In other words, put together some PDL data,
Processes (A) to (F) may be performed using this as one unit. For example, one scan in the main scanning direction in Figure 11B (
25-1, . . ) can also be processed as one image forming site.

FIG. 4 is a flowchart outlining a program executed by CPU 1 in the first embodiment.

First, the CPU 1 receives PDL data sent from the host computer and stores it in a buffer in the RAMB (step SL). Next, steps 5L02-5
At 106, the PDL data is developed into binary image data according to the procedure shown in FIG. 2, and written into the binary image memory. That is, in step 5102, the cpui first reads the PDL
The data is developed into multivalued data with multiple values per pixel, and in step 5103, correction processing of output element characteristics is performed. In the next step S4, CPtJl performs step 5103
The correction data obtained in step 5105 is binarized using a dither method or the like, and then written in the binary image memory in step 5105.

In this embodiment, all of these processes are performed by the CPU 1 as software processing. However, some or all of these processes may be performed using hardware. Further, instead of processing all PDL data at once, if steps 5L02 to 5105 are repeated for each small unit, the amount of intermediate data can be reduced.

Further, in this embodiment, all the PDL data necessary for printing is received and then expanded, but the PDL data may also be received in a predetermined unit and processed in each unit. In this case, the host computer is forced to wait, but there is an advantage that the amount of buffer in the RAM 3 is small.

Returning to the explanation of FIG. 4 again, when all PDL data has been developed, a print operation is performed in step 5107, and the operation returns to step S1.

As explained above, according to the first embodiment, by performing data modulation processing to correct the characteristics of the image forming element when converting a multi-valued image into a binary image, without increasing costs, The characteristics of the image forming element can be corrected at the stage of a multivalued image. As a result, for example, it is possible to obtain a good output image with less variation in density.

Moreover, since the memory for binary image data is sufficient for at least one image forming area, the memory capacity can be significantly reduced. Note that one image forming site is defined as
For example, if it is a page printer, the 11th B
For a printer that scans for image formation as shown in the figure, this refers to the amount for one scan.

(Second Embodiment) FIG. 5 is a block diagram showing the configuration of a printer that handles color multivalued images in a second embodiment of the present invention. In the following description, description of the same configuration as in the first embodiment will be omitted, and the explanation will focus on the different configuration.

The difference from the first embodiment is, firstly, that the data sent from the host computer 12 is a color multivalued image, and secondly, the image forming section 8 is ), yellow (Y), and black (K), which form a color image by superimposing color component images of four colors. Along with this, the binary image memory 7 is also C and M.

It is divided into four sections, 7-1 to 7-4, for Y. Further, as will be described later, in the output element characteristic correction process in the second embodiment, in addition to the dither pattern ROM 5, a dither pattern RAM 55 is provided which holds a dither pattern whose output element characteristics have been corrected. This dither pattern R
The AM 55 may be included in the RAM 3 which is the working RAM of the CPU (Also, the dither pattern ROM 5 and font ROM 4 may also be included in the program ROM 2 containing the CPU 1 program.

FIG. 6 shows that in the second embodiment, the CPU 1 converts the color multivalued image sent from the host computer into CM and K.
FIG. 2 is a diagram showing a procedure for developing into binary image data.

First, the color multivalued images sent from the host computer are red (R) and green (G).

In the case of an RGB multivalued image consisting of blue (B) data (a), CMY from RGB data (luminance)
Conversion to K data (density) is performed (b). However, when the data sent from the host computer is CMYK data (C), this process (b) is omitted.

This CMYK data (density value) is the coordinate value (x,
y) and expressed in color components (Color), DATA
1 (Co1or, x, y).

Next, in (d), binarization is performed using the dither method.

However, the dither pattern used is different from that of the first embodiment, and a dither pattern whose output element characteristics have been corrected is used (
f). A method of creating this dither pattern whose output element characteristics have been corrected will be explained. First, if the standard dither pattern is expressed by quadratic equation (5), TH(xx, 3'y) O≦XX, yy≦8・
...(5) Then, the corrected dither pattern MTH(xxx.

yyy) is created as shown in the following equation (6). That is, MTH
(xxx,yyy)=TH((xxx mad 8),
(yyy mod 8)) Xf(yyy) 0≦XXX≦8 0≦yyy≦128 (6). The corrected dither pattern MTH is corrected by lowering the threshold value in the dither pattern corresponding to a portion with a low average of 1 degree. The corrected dither pattern thus created is written into the corrected dither pattern RAM 55.

The data that has been binarized in step 17 using the corrected dither pattern created in this way has its output element characteristics also corrected at the same time, and is written into the binary image memory for each color component (e).

(Third Embodiment) FIG. 7 is a block diagram showing the configuration of an image processing apparatus according to a third embodiment of the present invention. The difference from the first embodiment is that the image processing device 50'' and the image forming device 58 are separated. Note that explanations of the same configurations as in the first embodiment will be omitted.

The image processing device 50'' exchanges commands with the image forming device 58 via the communication interface 56 and the communication signal line 57. In this case, the image processing device 50'' can be connected to a different image forming device. It is. on the other hand,
Since image forming element characteristic data differs from image forming apparatus to image forming apparatus, it is necessary to adopt a method in which these data are held on the image forming apparatus side and transferred to the image processing apparatus 50''.

FIG. 8 is a flowchart outlining a program executed by the CPUI in the third embodiment.

Compared to the flowchart of the first embodiment, when the power is turned on,
The difference is that image forming element characteristic correction data is received from the image forming apparatus 58 and stored in the image forming element characteristic RAM 54 (step S201). Note that the other operations (steps 5202 to 5209) are the same as those in the first embodiment described above, so their explanation will be omitted.

Note that the present invention brings about excellent effects particularly in bubble jet type recording apparatuses among inkjet recording apparatuses. This is because, according to such a method, higher recording density and higher accuracy can be achieved.

Regarding the alternative structure and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method is applicable to both so-called on-demand type and continuous type. In particular, in the case of the on-demand type, the electrothermal transducer placed corresponding to the sheet holding the liquid (ink) or the liquid path is required to respond to the recorded information and rapidly exceed nucleate boiling. Application of at least one drive signal that provides a temperature increase causes the electrothermal transducer to generate thermal energy to cause film boiling on the thermally active surface of the recording head. as a result,
This is effective because bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal. The growth and contraction of this bubble causes the liquid (ink) to be ejected through the ejection opening to form a small droplet (at least one droplet).If this drive signal is in the form of a pulse, the growth and contraction of the bubble will occur immediately and appropriately. This makes it possible to achieve liquid (ink) ejection with particularly excellent responsiveness, which is more preferable.This pulse-shaped drive signal is described in U.S. Pat. No. 4,463,359 and U.S. Pat.
262 is suitable. Further, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes a combination of ejection ports, liquid paths, and electrothermal converters (straight liquid path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, as well as a heat acting section. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600 which disclose arrangements placed in bending regions.
The present invention also includes a configuration using the specification of the above specification.

In addition, Japanese Patent Application Laid-Open No. 5-1191 discloses a configuration in which a slit common to a plurality of electrothermal transducers is used as a discharge part of the electrothermal transducers.
No. 9-123670, and Japanese Patent Application Laid-Open No. 5 (1973) disclosing a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
The effects of the present invention are also effective even with a recording head configuration based on Publication No. 9-138461. In other words, regardless of the form of the recording head, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus. Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration in which a single recording head is formed integrally. In addition, even the serial type as in the above example is a replaceable chip type that can be attached to the main body of the device to enable electrical connection with the main body of the device and supply of ink from the main body of the device. The present invention is also effective when using a recording head or a cartridge type recording head provided integrally with the recording head itself.

The present invention is also effective for full-line type recording heads in which the recording head does not move.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention may be used as an image output terminal for information processing equipment such as a computer, or may be used as a copying apparatus combined with a reader or the like, or as a facsimile apparatus having transmitting and receiving functions. It may be something to decorate.

In the present invention, the printer section may be of the BJ type, printing jet type, electrophotographic type (laser, LED), thermal transfer type, or silver halide type. Of course, it can be in color or black and white.

In addition, in the input image, PDL data, RG
In addition to B multivalue images and CMYK multivalue images, palette images and black and white multivalue images are also acceptable (and "0" - rOJ, rlJ → "
Two images may be used by converting the maximum density.

Furthermore, in addition to the dither method, the binarization process also uses the error diffusion method.
The average density preservation method may be used (as in the first embodiment, the data before binarization may be corrected, or as in the second embodiment, the threshold level may be corrected). Also good.

Furthermore, data modulation and binarization may be performed using software by a computer, or may be performed using hardware by providing a processing circuit.

[Effects of the Invention] As described above, according to the present invention, an image can be formed according to the characteristics of an image forming element, and the memory capacity can be saved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a black-and-white PDL compatible printer in the first embodiment of the present invention, and FIG. 2 is a diagram showing the procedure by which the CPU develops PDL data sent from a host computer into binary image data. , Fig. 3 is a diagram showing an example of a dither matrix used in the first embodiment, Fig. 4 is a flowchart outlining the program executed by the CPUI in the first embodiment, and Fig. 5 is a diagram showing an example of the dither matrix used in the first embodiment. FIG. 6 is a block diagram showing the configuration of a printer that handles color multivalue images in the second embodiment of the invention. K
FIG. 7 is a block diagram showing the configuration of an image processing device according to the third embodiment of the present invention, and FIG. 8 is a diagram showing the procedure for developing into binary image data. FIG. 9 is a block diagram showing the configuration of a conventional image forming apparatus. FIG. 10 is a PDL sent from a host computer.
Figure 11A is a diagram showing a schematic configuration of the print head 119 in the inkjet method; Figure 11B is a diagram showing the procedure by which the CPU 10I develops data into binary image data; Figure 11B is printing on paper 124 using the print head 119; Figures illustrating the method, Figures 11C and 11D, are diagrams illustrating the drawbacks of the conventional method. In the figure, 1,101-CPU, 2,1102-RO,3,
103. RAM, 4, 104-7 Onto ROM, 5.
105-... Dither pattern ROM, 6.106...
External interface, 7.7-1 to 7-4, 107...
・Binary image memory, 8,108...image forming section, 9,
109...Address generation section 1.・8.6...External interface, 5o...Printer, 50'...Color printer, 54...Image forming element characteristic RAM, 55
. . . dither pattern RAM, 56 . . . communication interface, 58 . . . image forming device.

Claims (8)

[Claims] (1) A developing means for developing data described in a page description language into multi-valued image data, a modulating means for modulating the multi-valued image data developed by the developing means, and multi-valued image data modulated by the modulating means. Binarize 2
digitization means; storage means for storing the binary image data obtained by the binarization means; 1. An image processing apparatus comprising: a transfer means for transferring converted image data. (2) An input means for inputting multivalued image data, a modulation means for modulating the multivalued image data inputted by the input means, and 2 for binarizing the multivalued image data modulated by the modulation means.
a digitizing means; and at least one of the binarized image data obtained by the binarizing means.
It is characterized by comprising a storage means for storing image forming units, and a transfer means for transmitting the binarized image data to an image forming means that performs image formation based on the binarized image data stored in the storage means. image processing device. (3) Image processing according to claim 1 or 2, wherein the image forming means includes an image forming element, and the modulating means includes a correction means for correcting characteristics of the image forming element. Device. (4) The image processing apparatus according to claim 3, wherein the correction means includes a setting means for manually setting information for correcting the characteristics. (5) The image processing apparatus according to claim 3, wherein the correction means includes a setting means for setting information for correcting the characteristic based on a test pattern outputted in advance by the image forming means. (6) The image processing apparatus according to claim 3, wherein the characteristics include density variation characteristics between the image forming elements. (7) The image processing apparatus according to claim 6, further comprising a holding means for holding the characteristic as a dither pattern. (8) The image forming element includes an ejection port for ejecting ink, and a discharging port provided at the ejection port to cause a change in state of the ink due to heat, and ejecting the ink from the ejection port based on the state change to create a flying image. 4. The image processing apparatus according to claim 3, further comprising thermal energy generating means for forming a liquid droplet.