JPH1093823A - Image processing unit and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent image quality by detecting a pattern specific to a medium gradation generated by dither processing or the like so as to prevent smoothing processing thereby reducing jaggy that is visual disturbance. SOLUTION: An address controller 102 reads image data from an image buffer 101 and gives the data to a shift register 104. Then a print image in the unit of a print width of a print head is expanded. A 4.4 picture element window 106 is set to the shift register 104 and a pattern matching lookup table 107 is always referenced thereby. When a pattern generated as a result of low resolution processing by a host computer is detected, smoothing processing is applied to a prescribed picture element. Then a medium gradation monitor window 105 is provided to the shift register 104 and when a pattern specific to medium gradation generated by dither or the like appears, the execution of smoothing processing is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and an image processing method for performing a smoothing process on an input image.

[0002]

2. Description of the Related Art In a conventional image smoothing process, an input image is binary and an output image is also binary, and a smoothing processing circuit for that purpose has, for example, a configuration as shown in FIG.

In FIG. 6, reference numeral 501 denotes a selector, 502
Is a lookup table (LUT), 503, 504
Is a delay element such as a D-FF, and 505 is a bitmap memory that stores a binary image. The number of delay elements is required by the number referred to by the lookup table 502, and is determined by the bit width of the memory element and the like.

When an address is passed from the address controller 506 to the bit map memory 505 in which an image is stored, predetermined image data is input to the delay element 503. The input data moves to the delay element at the subsequent stage every unit time and propagates to the delay element 504 at the last stage. The output of the illustrated delay element is input to the look-up table 502.

FIG. 7 is a diagram showing the effect of a conventional smoothing process. In the smoothing process, an output is generated for an input image having a certain characteristic by the look-up table 502, and data is changed to image data being propagated. Then, the output of the delay element at the last stage is returned to the bitmap memory 505 and written there.
For example, when input data as shown in FIG. 7 is input to the lookup table 502 and output data as shown in FIG. 7 is obtained, the result of synthesizing the image data on the shift register is “ "Composition result"
Zigzag images have been improved.

As described above, conventionally, a smoothing effect on a binary image can be obtained by processing with the smoothing processing circuit having the above configuration, and even if the original image is a low-resolution image, it is visually harmful. High jaggies can be suppressed and high quality images can be obtained.

[0007]

However, the above-mentioned conventional processing method has the following problems.

That is, in recent years, the accuracy of an image output device such as a printer has been improved, and it has become possible to handle multi-valued data. However, in the above-described conventional processing method, an effect of smoothing binary data can be expected. However, when multi-valued data is smoothed, there is a problem that image data must be binarized, or a binary region must be extracted and data changed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to perform a smoothing process and an anti-aliasing process even on a multi-valued input image. It is an object of the present invention to provide an image processing apparatus and an image processing method capable of visually performing optimal processing by switching processing according to.

[0010]

In order to achieve the above object, the present invention provides a storage means for storing input image data, a means for expanding the stored image data on a memory, Means for comparing an image pattern included in the image data with a predetermined image pattern, and processing means for performing image processing on a predetermined area of the image data based on the comparison result, wherein the processing means includes: When the image pattern included in the image data matches the predetermined image pattern, the image processing is performed on a predetermined area of the image data.

[0011]

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

FIG. 1 is a block diagram showing a main configuration of an image processing apparatus according to an embodiment of the present invention. In the figure, multi-valued image data is input to an image buffer 101 by a data input process. Address controller 1
02 generates a predetermined appropriate address to be described later for reading and writing of image data. The image data read from the image buffer 101 by the address controller 102 is stored in the data latch device 103 and then input to the shift register group 104 for each pixel. Here, as shown in FIG.
The output of a certain area of the shift register is an intermediate value monitoring window 105.

The pattern matching look-up table 107 receives an output of a certain area (pattern matching window 106) of the shift register group 104, and performs pattern matching only when image data having a certain characteristic is input. Lookup table 1
07 is output.

However, when an intermediate value is recognized by the intermediate value monitoring window 105, the output from the pattern matching lookup table 107 becomes invalid. Then, the pallet lookup table 108
Is a look-up table for converting an output from the image buffer, which is pseudo-multi-value data, into binary data.

Next, the features of the image processing apparatus according to the present embodiment will be described in detail.

Normally, when a host computer outputs a document containing a mixture of images and documents to be processed to a printer, in order to adapt the document to a printer to be output,
For the image, processing such as dithering and error inequality is performed, and for a document, data of a resolution matching the output printer is output from the font database.

However, in recent years, as the required resolution increases, the amount of data processing increases, which also causes a reduction in processing speed. In order to solve this, for example, the host computer performs processing at a low resolution, and the printer performs super-resolution processing. More specifically, the resolution of the output target printer is 1200 dpi × 600 dpi, and the processing resolution of the host computer is 300 dpi. However, the document area is processed with a 300 dpi binary image, and the image area is processed with a 300 dpi quinary.

FIG. 3 is a diagram showing pallet data held by the look-up table according to the present embodiment. When the smoothing process is not performed by the printer, the five values have the patterns shown in FIG. .

Normally, data from the host is stored in a print buffer, which is a buffer for storing an image to be printed, and is directly transferred to a print head, where printing is performed by discharging ink.

FIG. 2 is a diagram showing a print buffer (image buffer) according to the present embodiment. Here, the print buffer is divided into several sub-bands with the print width of the print head as a band. As shown in the figure, one sub-band is composed of 1 word = 32 bits for easy memory access, and one sub-band has a width of 8 pixels in order to express it as 4 bits = 1 pixel. .

Hereinafter, the smoothing process in the apparatus according to the present embodiment will be described.

When the address controller 102 shown in FIG. 1 outputs an address "0" and reads data from the image buffer 101, the read data is converted into 8-pixel data having a 4-bit depth. These are input to the shift register group 104. Then, the image data is shifted one pixel at a time by a system clock φ (not shown).
02 outputs the address “4” and outputs the image buffer 101
, And sends it to the shift register group 104.

Since the smoothing process is performed using two subbands as a basic unit, the address controller 102 outputs an address '50' next.
And the data read according to this address is
The data is sent to the shift register group 104. When the data read in this way is sequentially sent to the shift register and up to the data of the address 'F4' is sent to the shift register group 104, all the print images of a predetermined unit are developed on the shift register group 104.

The output of some shift registers has the above-mentioned pattern matching window (pattern matching window 106), through which the pattern matching lookup table 107 is referenced. The shift register according to this embodiment has 4 × 4
The data on the shift register is always matched.

FIG. 4 is a diagram showing an example of the smoothing effect by the look-up table according to the present embodiment.
In the figure, the area indicated by the halftone dot is the area to be matched in the lookup table, and the shaded area is the image synthesized by the output from the lookup table when the pattern occurs. is there. The data in the hatched portion in FIG. 4 represents the data shown in FIGS. Thus, a specific output is generated for some data.

In this embodiment, as described above, an intermediate value monitoring window 105 is provided separately from the pattern matching window. This is to invalidate the reference to the look-up table when a pattern indicated by reference numeral '2' or '3' in the pallet data shown in FIG. 3 appears. This is because when a pattern of “2” or “3” appears on the print data, it indicates that the neighboring image data is not a binary image but a multi-valued image. This is because performing a smoothing process on an image generates a visually harmful pattern.

However, since the pattern of the halftone "1" is likely to be the image data replaced by the smoothing processing, the smoothing is not invalidated even if the halftone "1" is detected. .

In this manner, the data that has passed through the shift register group is returned to the print data again. At this time, the original data is returned to the place where the original data was, and the data on the boundary between the two subbands is returned. Are configured on the image buffer as data subjected to smoothing processing.

With the above configuration, in this embodiment, pseudo smoothing processing is performed on the halftone image data shown in FIG. 3 by using the extended halftone shown in FIG. Then, by sequentially performing this processing, smoothing can be performed only on the area where the binary image is present for all the areas.

FIG. 8 is a flowchart showing an image processing procedure in the apparatus according to the present embodiment. In FIG. 5, in step S1, the input multi-valued image data is expanded in a memory, and in step S2, an image pattern included in the expanded image data is compared with a predetermined image pattern. As a result of this comparison, if the patterns match each other (YES in step S3), image processing is performed on a predetermined area of the multi-valued image data in step S4.
However, if the pattern does not match and a predetermined area of the image data includes a halftone image of a predetermined level of the multi-valued image, the predetermined area is not subjected to the above image processing (step S5). .

As described above, according to the present embodiment, the read image data is expanded on the shift register, and the image data having the specific pattern determined by the pattern patching is excluded from the smoothing process. 2
By performing the smoothing processing in the value area and not performing the smoothing processing in the multi-value area, it is possible to reduce jaggies causing visually obstruction and obtain a good image.

Further, high-speed raster data can be generated by performing low-resolution and multi-value processing on the host side, and high-resolution processing can be performed on the output side of the image, so that the characteristics of the image in a predetermined area can be reduced. A corresponding high-quality image can be obtained.

The present invention may be applied to a system constituted by a plurality of devices or to an apparatus constituted by a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

[0034]

As described above, according to the present invention,
By performing image processing on a corresponding predetermined area based on an image pattern included in image data, a high-quality image corresponding to the property of the image can be obtained.

[0035]

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a print buffer (image buffer) according to the embodiment.

FIG. 3 is a diagram showing pallet data held by a lookup table according to the embodiment;

FIG. 4 is a diagram illustrating an example of a smoothing effect by a look-up table according to the embodiment;

FIG. 5 is a diagram showing extended pallet data according to the embodiment;

FIG. 6 is a block diagram illustrating a configuration of a conventional smoothing processing circuit.

FIG. 7 is a diagram illustrating an effect of a conventional smoothing process.

FIG. 8 is a flowchart showing an image processing procedure in the apparatus according to the embodiment.

[Explanation of symbols]

 Reference Signs List 101 Image buffer 102 Address controller 103 Data latch device 104 Shift register group 105 Intermediate value monitoring window 107 Pattern matching lookup table

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Ninomiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (4)

[Claims] A storage unit for storing input multi-valued image data; a unit for expanding the stored multi-valued image data on a memory; an image pattern included in the expanded multi-valued image data; And a processing unit that performs image processing on a predetermined area of the multi-valued image data based on the comparison result, wherein the processing unit is included in the multi-valued image data. When the image pattern matches the predetermined image pattern, the image processing is performed on a predetermined area of the multi-valued image data, and a halftone image of a predetermined level of the multi-valued image is displayed in the predetermined area. The image processing apparatus according to claim 1, wherein, if included, the image processing is not performed on the predetermined area. 2. The image processing apparatus according to claim 1, wherein the predetermined image processing is a smoothing processing, and the smoothing processing is performed when only the binary image is included in the predetermined area. 3. The image processing apparatus according to claim 1, wherein the predetermined image pattern is stored in a lookup table for pattern matching. 4. A step of expanding input multi-valued image data on a memory; a step of comparing an image pattern included in the expanded multi-valued image data with a predetermined image pattern; And a processing step of performing image processing on a predetermined area of the multi-valued image data, wherein, in the processing step, when the image pattern included in the multi-valued image data and the predetermined image pattern match,
The image processing is performed on a predetermined area of the multi-valued image data, and when the predetermined area includes a halftone image of a predetermined level of the multi-valued image, the image processing is performed on the predetermined area. An image processing method characterized by performing no processing.