JP2002337395A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor in which a restoration lookup table on the print mechanism side can be rewritten frequently under a state where the number of connecting lines of a device is decreased and print gradation control can be effected more efficiently on a low cost hardware. SOLUTION: An image processor comprising a print mechanism 100 having a mechanism for providing M kinds of different print representations of each pixel, and an imaging block (image generating section) 200 for using limited K values selected from M kinds of print representations is further provided with a rewritable numeric value converting section for converting input of the K values into M kinds of print representations at the print mechanism 100, and a mechanism for superposing rewrite information at the numeric value converting section on print output information from the image generating section 200 and separating them at the print mechanism before being inputted to numeric value converting section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus including a printing mechanism for performing a plurality of gradation expressions in one pixel and having a pixel attribute control mechanism.

[0002]

2. Description of the Related Art Along with the spread of electronic devices and personal computers, peripheral devices have been widely spread. One of the peripheral devices is a printout device. Printing apparatuses, such as electronic devices and personal computers, which output processing results on paper, have become more popular due to lower prices and improved performance.

[0003] Such a printing device or an image output printing device such as a conventional ink jet printer or a laser printer is generally provided with a single printing mechanism for interpreting a printing command from a host or rendering characters. Has a built-in computer.

Communication is performed with devices such as a host computer, and commands, print data, and the like are received from the host computer, and image data and characters received on a bitmap memory are rendered and rendered for printing.

[0005] Improvements in computer hardware have made it possible to handle more complex data, and have more commonly handled color images. Along with this, color printing has also been advanced in print output devices.

[0006] It has become important how to output smooth gradations in various printing mechanisms, which has conventionally been simple binary printing.

[0007] Even if the color information is lost when the original data is color gradation data, a satisfactory output result cannot be obtained with a printing apparatus which cannot sufficiently express gradation. For this reason, it is equally important whether smooth gradation expression can be performed not only in color but also in a monochrome printing device.

In gradation printing, generally, a printing mechanism in which pigments of all densities are individually held and shot is an unrealistic amount in consideration of natural surface output. Normally, the gradation expression in the printing mechanism is expressed by the area ratio of the printing portion and the non-printing portion of some primary color pigments. For example, in printing, primary color pigments corresponding to three primary colors and black are prepared and output.

[0009] In order to enhance the specific color development,
Printing is performed by preparing additional pigments for the colors. In the printing mechanism, similarly, pigments of three to four colors are individually prepared and printed. In some print output systems such as the electrophotographic system, the nonlinearity of the boundary between the drawing surface portion and the non-drawing surface portion corresponding to the dot gain in the printed matter is large,
It is difficult to express gradation with a single pixel. In such a printing method, a gradation is expressed by the number of dots in a unit area in units of a plurality of surface element groups.

However, even in image processing for performing gradation expression using a plurality of surface element groups, gradation expression in pixels is not wasted.
In surface processing such as shading, it is necessary to reduce the unit area of shading so as to make it visually inconspicuous. For a printing mechanism having a printing mechanism with a resolution of about 1000 dpi or less, a gradation expression within a unit area is required. Can not hold a sufficient number of pixels. Therefore, when there is a gradation expression mechanism in a pixel, it is necessary to secure a sufficient gradation by using it together with gradation expression based on the number of dots in a unit area.

There are several methods for expressing gradation in a surface element. One of the methods relatively easily adopted in a scanning type printing mechanism is a method of performing PWM processing in a pixel. The resolution of the PWM mechanism for each surface element can be designed to be sufficiently high in terms of a circuit.

However, although a sufficient number of gradations should be assigned to one pixel electrically and optically by the PWM processing, the pigment actually adheres to the output paper in the electrophotographic system, thermal transfer, sublimation or the like. Is very nonlinear, and many gradation steps that can be generated by the PWM circuit are out of the used area. Even if the hardware of the PWM expression has a resolution of 8 bits, a correspondence often occurs that the difference in the size of the print dots is only at most ten steps.

It is important to design the image memory for storing the image data to be printed out as small as possible in order to reduce the cost of the printing apparatus.

For this reason, in an actual print output device, a process of selecting and using a pattern having high effectiveness in actual gradation expression from all expressible print patterns at any stage. Has been implemented. The method of performing this process on a bitmap image on a print memory is the method having the highest degree of freedom and high expressive power.

However, this method is inefficient because information is evenly allocated to many patterns that are meaningless for gradation expression. In an actual product, as described above, it is necessary to design the image memory as small as possible due to cost.

Further, an increase in the capacity of the image memory means an increase in the load of image processing.

Therefore, in practice, a method of preparing and converting a look-up table for selecting a pattern corresponding to the density to be expressed is often used. That is, what is written on the image memory is not a direct pattern,
Numbers are sequentially assigned to the selected patterns, and the pattern numbers are written.

On the printing mechanism side, the transmitted pattern number is converted again by the lookup table for restoration, and the pattern is restored and output. If you use this method,
Since the effective information amount that can be actually expressed by the printing mechanism matches the information amount of the image memory, an efficient system can be formed.

[0019]

The density characteristic of an actual printing mechanism changes variously due to individual differences, changes over time, disturbances such as temperature, humidity, and paper characteristics. For this reason, the selection of the optimal pattern varies depending on the individual and even within the same individual, so that the optimal pattern setting must always be dynamically selected.

For this reason, in order to output a high-quality and stable image, each look-up table is not fixed in the system of the image output device, and rewriting setting means is required.

The data set in the restoration look-up table on the printing mechanism side is inevitably a plurality of multi-valued data. To set the multi-valued data, a multi-bit data is required between the printing mechanism and the image generating unit. Connection line is required. This increases the cost of connectors and connections. For this reason,
Many printing mechanisms select a circuit configuration that reduces the number of connections by a different use than the connection of other more frequently used signal lines. For example, multivalued data is serially transferred to reduce the number of connections, or a configuration is adopted in which a dedicated control line is not prepared by incorporating the data as a part of various status control information commands.

In such a configuration, table rewriting can be performed only in page units. In a printing mechanism with a small number of pattern numbers that can be set on the page memory, the restriction of rewriting in page units is disadvantageous in terms of image expression. This is because, by rewriting the pattern setting values in real time, the number of pattern numbers on the page memory increases at least the number of patterns used, and a method of effectively increasing the number of gradations can be used.

The present invention has been made in view of the above circumstances, and an object thereof is to frequently rewrite a restoration lookup table on the printing mechanism side while reducing the number of device connection lines. Another object of the present invention is to provide an image processing apparatus capable of performing more efficient print gradation control on low-cost hardware.

[0024]

In order to achieve the above object, the present invention provides a printing mechanism having a mechanism for performing M types of different printing expressions for each pixel, and a printing mechanism having a limited number of M types of printing expressions. In an image processing apparatus having an image generation unit that selects and uses a K value,
A rewritable numerical conversion unit for converting an input of a value into M types of printing expressions; And a mechanism for human power is provided.

[0025]

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

FIG. 1 is a configuration diagram of an image processing apparatus according to the present invention. In this embodiment, a laser drawing type electrophotographic printing mechanism is included as a configuration. The laser-drawing type electrophotographic printing mechanism scans laser light,
The printing surface is formed by combining paper conveyance. A synchronizing signal generating circuit for synchronizing each optical scan with the printing timing is provided in the printing mechanism.

In FIG. 1, reference numeral 200 denotes an image forming block, 201 denotes a CPU, and 202 denotes a ROM.
M stores a program for operating the CPU 201 and various data for image generation. Reference numeral 203 denotes a RAM, which temporarily stores data before processing sent from an external device, receives and stores a program from the outside, and stores data from a scanner.

Reference numeral 204 denotes an interface with an external device, which may not be implemented in a configuration such as a copy-only machine. Reference numeral 205 denotes a scanner, which may not be mounted depending on a configuration such as a laser printer. Reference numeral 206 denotes a FIFO, which arbitrates the timing of data transmission of the image generation unit and data request of the printing mechanism. The timing generation circuit for this is 207
It is.

Reference numeral 208 denotes an image clock, which generates a print output timing from a synchronizing signal from the print mechanism and the image clock, and supplies the print output timing to the FIFO 206. Reference numeral 300 denotes a bus line, and reference numeral 301 denotes an image transmission line. In the present embodiment, the image information developed on the page memory has a configuration in which 4 bits per color, that is, 16 patterns are selected. That is, the image transmission line 301 is constituted by four signal lines.

Reference numeral 302 denotes a scanning synchronization signal, and reference numeral 303 denotes a modulation value input of the laser modulation circuit 103. In the present embodiment, the modulation value input 303 indicates a configuration of a 12-bit input. 304 is a laser drive signal, and 305 is an image clock.

It becomes active only when data is actually sent from the FIFO 206. 100 is an outline of a printing mechanism omitting a paper transport unit, 102 is a conversion table, 103 is a laser modulation circuit, 104 is a laser light source, 105 is a polygon mirror, and the polygon mirror 105 scans a laser beam emitted by the laser light source 104. Is done. The laser beam passes through the optical systems 106 to 108 and is converted into a uniform scan on the photoconductor 109.

Reference numeral 110 denotes a synchronization sensor, which is a light detection sensor, and serves as a synchronization signal for determining a timing at which image data is transmitted for optical scanning. The effective print area is set at a certain timing from the synchronization signal, and the image generation unit needs to send out the image information in accordance with this timing. In the present embodiment, a pattern set value is prepared in an area deviating from the timing of the effective print area, and information is transmitted to the printing mechanism. FIG. 2 shows this timing.

In FIG. 2, the pattern registration data is superimposed on the blanking time after the generation of the synchronization pulse until the print effective area is reached.
01 is used for multiplexing.

If the registered pattern superimposed on the image transmission line 301 cannot be accurately separated, the pattern registration data is added to the print output as noise. For this reason, a mechanism for accurately separating registered pattern information is required. In the present embodiment, the mechanism is held inside the conversion table 102. FIG. 3 shows the conversion table 1
02 is shown in detail.

In FIG. 3, the registered pattern information and the image information are separated so that they can be easily grasped visually. However, in terms of hardware processing, it is simpler to treat all data as the same data. For this reason, each 12-bit pattern registration data set in the image generation unit is divided into three in order to be treated in the same manner as 4-bit pixel information.

The information written in the FIFO 206 has a format as shown in FIG. N is the number of print pixels per scan. The symbols L, M, and H are divided registration pattern information. In FIG. 4, the information is 4 bits per word, and 4 bits × 4 bits prior to the original image information.
This is a form in which a header of 3 divisions = 48 words is added to the original image information. The pattern registration data, which is additional information, may be developed in advance on the edge of the image development area of the page memory, or may be individually written as a header before writing each scanning time signal to the FIFO 206.

Reference numerals 400H to 415L denote pattern registration registers. Each of the registration registers 400H to 415L has setting inputs 500 to 547 and selection inputs 550 to 555. When the setting inputs 500 to 547 become active, the data on the image transmission line 301 is taken in as setting values.

Further, it has a registration data output and a setting data input. The setting data input is connected to the image transmission line 301. It should be noted that since the connection of all the setting inputs 500 to 547 is complicated, only a part of the connection is shown in FIG.

500 is 400H, 500 is 400M, 5
00 are sequentially connected to 400L. These are connected in the same order as the data order in FIG. Also, it outputs the data taken in when the selected manual power becomes active. The selection input is H, M, L shared, and the register selected by 452 becomes the active output. 450 is a down counter.

At the time of reset, the number of words in the header + 1
49 is set. The scan synchronization signal 302 is connected to the reset input, and is reset by the input of the scan synchronization signal 302. Clock clock 3
05 is connected and counted down. 451 is a demultiplexer.

5 after reset by input from 450
The control lines 00 to 548 are sequentially activated from 500. When the input value is 49, 500 becomes active, and when the input value is 48, 501 becomes active.
The input value 1 activates 547. Reference numeral 548 denotes a normal print mode signal. When this signal becomes active, the input operation to the pattern registration registers 400H to 415L ends.

When the output of 450 becomes 0, the control line 5
48 is active until the next reset input, activating the output mask 453 and demultiplexer 452 to enable the pattern conversion input and table output.

The pattern number sent from the image generation unit is converted by the demultiplexer 452 into a value registered in the register, and the data is output to the laser modulation circuit 103.

Thus, by adopting the configuration as in the present embodiment, it is possible to use more patterns in a printing apparatus having a page memory configuration in which only 16 patterns can be originally selected.

[0045]

As is apparent from the above description, according to the present invention, a printing mechanism having a mechanism for performing M kinds of different printing expressions for each pixel and a printing mechanism having only M types of printing expressions are limited. In an image processing apparatus having an image generation unit that selects and uses a K value, a rewritable numerical value conversion unit that converts an input of a K value into M types of print expressions in the printing mechanism, and an output from the image generation unit Because the rewriting information of the numerical conversion unit is superimposed on the print output information and a mechanism is provided in the printing mechanism and separated by the printing mechanism and a manual operation is provided in the numerical conversion unit. The look-up table can be rewritten, and the effect that more efficient print gradation control can be performed on low-cost hardware can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image processing apparatus according to the present invention.

FIG. 2 is a diagram showing a signal waveform of image transmission.

FIG. 3 is a detailed diagram of a conversion table.

FIG. 4 is a diagram showing a format written to a FIFO.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 printing mechanism 102 conversion table 103 laser modulation circuit 104 laser light source 105 polygon mirror 106-108 optical system 109 photoconductor 110 synchronous sensor 200 image forming block 201 CPU 202 ROM 203 RAM 206 FIFO 301 image sending line

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C062 AA32 AB17 2C262 AA05 AB07 AB20 BB01 BB07 BB27 BC01 GA14 GA15 5B057 AA11 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB16 CC01 CE11 CH07 CH08 5C077 LL19 MP01 PQ23 P02

Claims (1)

[Claims] 1. An image processing apparatus comprising: a printing mechanism having a mechanism for performing M types of different printing expressions for each pixel; and an image generating unit for selecting and using a limited K value from the M types of printing expressions. In the apparatus, a rewritable numerical conversion unit that converts an input of a K value into M types of printing expression in the printing mechanism, and superimposing rewriting information of the numerical conversion unit on print output information output from an image generation unit. An image processing apparatus comprising: a printing mechanism provided with a mechanism for separating and manually inputting a value to a numerical value conversion unit.