JP2002283620A - Image processing method and image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a printing time when printing does not require a high image quality. SOLUTION: When image data is developed, a printer driver 110 makes a decision whether a print object requires a high image quality or not. Halftoning, e.g. error diffusion, is performed in order to attain a high image quality if high image quality is required. Halftoning, e.g. dithering, is performed if high image quality is not required in order to shorten the printing time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a printing system, and more particularly to a printing system for switching halftone processing according to print contents.

[0002]

2. Description of the Related Art As an output device of a computer, there is known an ink jet printer which forms dots by using several colors of ink ejected from a plurality of nozzles provided in a head and records an image. Inkjet printers are
It is widely used to print images processed by a printer host such as a computer in multiple colors and multiple gradations. Inkjet printers usually turn on and off dots for each pixel.
Expressed in two gradations of OFF. For this reason, the image is printed after image processing for expressing the gradation of the original image data by the dispersibility of dots, that is, so-called halftone processing.

There are several methods for halftone processing, and typical and frequently used methods include an error diffusion method and a dither method. The error diffusion method determines whether a dot is on or off based on a magnitude relationship between a predetermined threshold value and each pixel, and, based on this determination, assigns a density error generated for each pixel to a peripheral pixel at a predetermined rate. To minimize the local density error. The dither method compares each area value of a dither matrix in which predetermined threshold values are arranged in a matrix and the gradation value of image data for each pixel, and determines dot on / off based on the magnitude relationship between the two. I do.

It is generally considered that the error diffusion method can display important halftones beautifully in a full-color image such as a photograph. In recent years, error diffusion processing has been mainly used from the viewpoint of high image quality of a printer. I have.

[0005]

The error diffusion method is suitable for high-quality output of a full-color image such as a photograph as described above. It is considered that an unnecessary load is being spent.

In general, when printing images other than full-color images such as photographs, it is better to print images with higher image quality than necessary.
It is considered that printing at high speed is often desirable.

An object of the present invention is to provide a technique for shortening the printing time for printing that does not require high image quality.

[0008]

According to the present invention, there is provided an image processing method for generating image data by rasterizing image data and performing halftone processing on the image data. When performing, it is determined whether or not the target image data includes data to be printed in high quality, and if the data to be printed in high quality is included, the image generated from the image data is determined. The method is characterized in that halftone processing capable of obtaining high image quality is performed on data, and otherwise, halftone processing capable of performing high-speed processing is performed on image data generated from the image data. An image processing method is provided.

[0009]

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

FIG. 1 shows the configuration of a printing system to which the present invention is applied. As shown in FIG. 1, the printing system includes:
A host computer 1 for realizing various processing by an application, printing processing by a printer driver, and the like.
0, and a printer 30 connected to the host computer 10. However, the configuration of the printing system is not limited to this.

The host computer 10 has a CPU (Central Processing Unit) 1 for executing various programs.
1. RAM for temporarily storing data and programs
(Random Access Memory) 12, ROM in which various data, various programs, and the like are stored in a nonvolatile manner in advance
(Read Only Memory) 13 and a printer interface 14 for transmitting and receiving data to and from the connected printer 30. Host computer 10
Stores a program or the like read into the RAM 12 into the CPU 11
Is executed and performs predetermined processing, thereby functioning as a printer host. The host computer 10 also includes an internal or external auxiliary storage device 24,
A display device 21 such as a color display, an input device 22 such as a mouse and a keyboard, and a media reading device 23 that reads data from a recording medium such as a CD-ROM are connected.

The printer 30 is, for example, an ink jet printer capable of performing color printing. Printer 30
Performs printing based on print data sent from the host computer 30.

Next, a functional configuration realized by the printing system will be described with reference to a block diagram of FIG.

In FIG. 1, a printer driver 110
Has a function of reading image data 100 generated by an application, converting the image data into print data that can be interpreted by the printer 30, and transmitting the print data to the printer 30 via the printer interface 14.

For this reason, the printer driver 110 includes a rasterizer 111 for expanding image data composed of print commands into image data, which is a group of dots, in band units, a color conversion process for image data, and a halftone process. , A user interface unit 113 for receiving print settings from the user, and a lookup table 114 to be referred to during color conversion processing.

In the present embodiment, the rasterizer 111 includes a print content determining unit 111a that determines whether a print target includes, for example, a photograph in accordance with a command included in image data. The halftone processing unit includes a halftone switching unit 112a that switches a halftone method used for halftone processing. In the present embodiment, the halftone processing that can be switched by the halftone switching unit 112a is an error diffusion method and a dither method. However, it is not limited to these.

Upon receiving a print command from the user, the user interface unit 113 displays, for example, a print setting screen 500 as shown in FIG. 3 on the display device 21 and receives print settings from the user. As shown in the figure, the print setting screen 500 includes a paper type setting column 501,
Paper size setting field 502, ink setting field 503, print quality setting fields 504 and 505, and number of print copies setting field 506
And a cancel button 507 for canceling the printing process
And a print execution button 508.

The user can make various settings on this screen 500 and perform desired printing on paper type, paper size, ink, number of copies, and the like. In the print quality setting fields 504 and 507, print quality can be set. For example, if "fine" is selected in the print quality setting field 504, high quality printing can be performed, and "fast"
When is selected, the image quality is lowered and printing at a high printing speed can be performed. These are known in the prior art. In the present embodiment, “automatic”
When 505 is selected, the print quality can be automatically changed according to the print target. That is, to print
For example, printing can be performed with high image quality when a photograph is included, and printing can be performed at a high speed otherwise. The operation of the printing system at this time will be described later.

The look-up table 114 converts the color expression of the RGB format (R: red, G: green, B: blue) used in the display device 21 into the CMYK format (C: cyan, M: magenta, Y) used for printing. : Yellow, K: black). The color expression format to be converted is RGB format, CMY
It is not limited to the K format.

Next, the operation of the printing system having the above configuration will be described with reference to the flowchart of FIG. In addition,
In this description, an application executed on the host computer 10 responds to a print request from a user,
It is assumed that the image data 100 has already been created.

A program for causing the printing system to execute the operations described below is, for example, a CD-RO.
It can be recorded on a recording medium such as M and distributed.
Then, the printing system can read the program recorded on the recording medium via the media reader 23, for example.

First, at the time of accepting a print request, the printer driver 110 prints a print quality setting field 50 of the print setting screen 500.
It is checked whether "automatic" is selected in step 5 (S10).
1). As a result, when "automatic" is not selected, conventional normal printing is performed (S106).

On the other hand, when "automatic" is selected in the print quality setting column 505, the rasterizer 111 of the printer driver 110 interprets the image data in a predetermined band unit, and The data is developed (S102). At this time, the print content determining unit 111a of the rasterizer 111 checks whether or not the image data includes data to be printed with high image quality (S103).

Here, it can be determined whether or not data to be printed with high image quality is included, for example, by determining whether or not a print command includes a photo drawing function. That is, if a photo drawing command is included in the print command, it is determined that the image data includes a photo to be printed with high image quality. Alternatively, the number of bits per pixel may be acquired from the print command, and if the number of bits is, for example, 24 bits or 16 bits or more, it may be determined that the data is data to be printed with high image quality. However, the method of determining whether or not data to be printed with high image quality is included is not limited thereto. For example, if the image data is composed of only monochrome data, it may not be included in data to be printed with high image quality.

In this process, the developed image data is
When it is determined that data to be printed with high image quality is included, for example, information indicating that high image quality processing is required is written in the header portion of the image data.

The determination as to whether data to be printed with high image quality is included may be made on a page basis or on a band basis. Then, when performing in page units, information can be written in the page header portion, and when performing in band units, information can be written in the header portion of the image data in band units. FIG. 5 is a flowchart for explaining the processing when the determination is made in band units. Processing S106 is performed instead of processing S102 shown in FIG.
107 is added. That is, it is determined whether or not high-quality print data is included (S103) for each band.

Next, the halftone processing section performs color conversion processing and halftone processing on the generated image data. In the color conversion processing, usually, the color expression of the image data represented in the RGB format is converted into the look-up table 114.
, And performs an interpolation process as necessary to convert the image into a CMYK format color expression. Next, the halftone processing unit 11
Step 2 refers to the header of the image data to check whether information indicating that high-quality processing is required is written. When it is determined whether data to be printed with high image quality is included for each page, the page header is referred to, and when it is determined for each band, the header portion of each image data is referred to. To

As a result, when information indicating that high-quality processing is required is written, the image data is expressed by an error diffusion method capable of beautifully expressing half-tones and printing with high quality. Processing is performed (S10
5). On the other hand, if the information indicating that the high image quality processing is necessary is not written, the halftone processing is performed using the simple and fast processing dither method (S104).

In this manner, an image requiring high image quality such as a photograph is subjected to a process of obtaining high image quality such as an error diffusion method, and an image other than the image is subjected to a fast process such as a dither method. can do.

Then, the printer driver 110 compiles the halftone-processed image data in page units,
The print data is converted into a format that can be interpreted by the printer 30 to create print data. The print data is transmitted to the printer 30 via the printer interface 14, and printing is performed.

The present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above embodiment, when high image quality processing is not required, the halftone processing is switched to a simple dither method to increase the printing speed. Here, the lookup table to be referred to may be changed. That is, in addition to the normally used look-up table, for example, the gradation is reduced (for example, 2
A prepared look-up table having a small size (56 gradations) may be prepared, and if the print target does not require high image quality processing, the look-up table may be switched to perform the color conversion processing. This makes it possible to further reduce the printing time in the case of printing that does not require high image quality processing.

In the above embodiment, the print setting screen 5
When "auto" 505 is not selected in the print quality setting column of 00, conventional print processing is performed. However, high-quality processing is also required when “automatic” is not selected in the print quality setting field 505 and “fast” is selected in the print quality setting field 504 or in all cases. If it is determined that high-quality processing is not necessary, simple halftone processing or the like may be performed.

[0034]

As described above, according to the present invention, the printing time can be shortened for printing that does not require high image quality.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a configuration of a printing system to which the present invention is applied.

FIG. 2 is a block diagram for describing a functional configuration realized by a printing system.

FIG. 3 is a diagram illustrating an example of a print setting screen 500.

FIG. 4 is a flowchart for explaining the operation of the present embodiment.

FIG. 5 is a flowchart for explaining the operation of the present embodiment when making a determination in band units.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Host computer 11 ... CPU 12 ... RAM 13 ... ROM 14 ... Printer interface 21 ... Display device 22 ... Input device 23 ... Media reading device 24 ... Auxiliary storage device 30 ... Printer 100 ... Image data 110 ... Printer driver 111 ... Raster riser 112 ... Halftone processing unit 113 ... User interface unit 114 ... Lookup table

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) 5C077 F term (reference) 2C087 AA15 AA16 AB01 AB05 AC07 BA03 BA07 BA12 BD01 BD05 CA05 CB18 DA02 2C187 AC08 AE01 2C262 AA02 AA24 BB01 BB06 BB08 EA04 EA06 EA18 5B021 AA01 BB01 BB02 LG08 5B057 AA11 CA08 CA12 CA16 CB07 CB12 CB16 CC01 CE13 CH07 CH18 5C077 NN19 PQ08 PQ23 TT02

Claims (8)

[Claims] In an image processing method for generating image data by rasterizing image data and performing halftone processing on the image data, it is determined whether or not target image data includes data to be printed with high image quality. Judgment, if data to be printed with high image quality is included, halftone processing that can obtain high image quality is performed on the image data generated from the image data, otherwise, An image processing method, comprising: performing halftone processing for performing high-speed processing on image data generated from the image data. 2. An image processing apparatus for generating image data by rasterizing the image data and performing halftone processing on the image data, comprising the steps of: determining whether the target image data contains data to be printed with high image quality; Image data determining means for determining, and if data to be printed with high image quality is included, halftone processing capable of obtaining high image quality is performed on image data generated from the image data; If not, an image processing apparatus comprising: halftone switching means for performing halftone processing capable of performing high-speed processing on image data generated from the image data. 3. The image processing apparatus according to claim 2, wherein the image data discriminating means determines whether the image data includes a photo drawing command,
An image processing apparatus characterized in that, when the number of bits per pixel represented by image data exceeds a predetermined number, it is determined that the image data includes data to be printed with high image quality. . 4. The image processing apparatus according to claim 2, wherein the halftone processing capable of obtaining high image quality uses an error diffusion method. 5. The image processing apparatus according to claim 2, wherein the halftone processing capable of performing the high-speed processing uses a dither method. . 6. The image processing apparatus according to claim 2, wherein said image data discriminating means includes data to be printed with high quality in image data in page units or band units. An image processing apparatus for determining whether or not the image processing has been performed. 7. A program executable in an image processing apparatus for generating image data by rasterizing image data and performing halftone processing on the image data. Image data discrimination processing for determining whether data to be printed with high image quality is included, and if data to be printed with high image quality is included, image data generated from the image data The image processing apparatus uses a halftone method that can obtain image quality; otherwise, a halftone switching process that uses a halftone method that can perform high-speed processing on image data generated from the image data is applied to the image processing apparatus. A program characterized by being executed. 8. A recording medium on which the program according to claim 7 is recorded.