JP2002120411A - White sheet detector and image recorder, imaging apparatus and image reader comprising it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white sheet detector which can detect a white sheet in a short processing time. SOLUTION: Only the image data of K component is subjected to white sheet detection processing (108) and then compressed before being stored in an RAM 18. Image data of other YMC components is compressed and held in the RAM 18 (110-114) and then it is compared with the compressed data of K component where a white sheet is detected thus performing white sheet detection of one page (116-130). In other words, white sheet detection only of K component is performed and other components are compared with K component where a white sheet is detected thus detecting a white sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blank sheet detecting apparatus and an image recording apparatus, an image forming apparatus and an image reading apparatus using the same, and particularly to whether or not image data of an area of a predetermined size is blank. The present invention relates to a blank sheet detecting apparatus capable of detecting the above in a short time and with high accuracy, and an image recording apparatus such as a printer, an image forming apparatus, and an image reading apparatus such as a scanner using the same.

[0002]

2. Description of the Related Art Conventionally, various methods for detecting a blank sheet have been proposed, for example, the techniques described in JP-A-4-220366 and JP-A-5-127449. According to the technology described in Japanese Patent Application Laid-Open No. Hei 4-22036, it is checked whether all bits of the print data are blank, and if the print data is a blank image, the print data is discarded, thereby clearing a blank page. I try not to waste it.

According to the technique described in Japanese Patent Application Laid-Open No. 5-127449, when the bit information of all the dots of the image information is "0" indicating white, the image information is a blank sheet, and the printing process is not performed. Only, or not to discharge the paper in addition to the printing process.

Further, there is a technique described in Japanese Patent Application Laid-Open No. 8-282055. In this technique, when the minimum rectangular area to be printed does not overlap the print area, the print area is a blank area. Deciding.

[0005]

However, in the conventional blank page detection, all bit information is searched, and if all the bit information is "0" (white), it is determined that the page is blank.
There is a problem that it is necessary to search all the bits for one page, and a lot of processing time is required.

In recent years, the resolution has been increased,
The number of bits per page is increasing proportionally. In the case of color, there are page information for four colors of cyan (C), magenta (M), yellow (Y), and black (K), and the number of bits to be searched increases as the resolution increases. There is a problem that the processing time also increases in proportion to the number of bits.

Further, in the technique described in Japanese Patent Application Laid-Open No. 8-282055, it is determined whether or not a minimum rectangular area for each piece of drawing information overlaps a print area. If all pieces of drawing information do not overlap, it is determined that the sheet is blank. When the drawing information per page is small, the efficiency is high, but the processing time increases in proportion to the number of drawing information. Naturally, in the case of color, the determination process is required for the page creation of each of the four colors (cyan (C), magenta (M), yellow (Y), and black (K)). There is a problem that it increases.

Further, in the above-described technique, in any case, in the case of color, four times as much processing is required as in black and white.

The present invention has been made in consideration of the above facts, and provides a blank sheet detecting apparatus capable of detecting a blank sheet in a short processing time, and an image recording apparatus, an image forming apparatus, and an image reading apparatus using the same. Aim.

[0010]

According to a first aspect of the present invention, there is provided an image processing apparatus comprising: a plurality of image data of a plurality of components for forming a color image; Detecting means for detecting blank data; comparing means for comparing the image data of the reference component with image data of the remaining components; and determining blank paper based on the detection result of the detecting means and the comparison result of the comparing means. A blank sheet determination unit.

According to the first aspect of the present invention, the detecting means includes a predetermined reference component image data among a plurality of component image data (for example, four YMCK components) for forming a color image. Of blank data is detected. The blank page data can be detected, for example, by searching all the image data and determining whether or not the data matches the data representing a blank page (no image is recorded). Then, the comparing means compares the image data of the reference component, for which blank data has been detected by the detecting means, with the image data of the remaining components to determine whether the image data of the other components is blank. Since the determination can be made, the blank page determination unit can determine the blank page from the detection result of the detection unit and the comparison result of the comparison unit. Further, by adding a simple configuration of providing a compression unit for compressing image data of the reference component and image data of other components, blank page detection can be performed in a shorter processing time than detection of blank page data of all components. This has the effect.

For example, when the image data of the reference component for detecting blank data is detected by the detecting means as blank, the image data of other components and the blank sheet are detected by the comparing means. By comparing the image data of the reference component, it is possible to detect whether or not the image data of the other components is a blank page.The blank page determining unit determines a blank page based on the detection result of the detecting unit and the comparison result of the comparing unit. Can be determined. That is, in this case, assuming that the image data of all the components match, the reference component for which blank data has been detected by the detecting means is blank, so that the blank determining means may determine that the blank is blank. If any one does not match, it can be determined that the page is not blank.

According to a second aspect of the present invention, the image processing apparatus further includes compression means for compressing the image data of the reference component, for which blank data has been detected by the detection means, and the image data of the remaining components. It may be. By further providing the compression means, the image data of a plurality of components is compressed to reduce the size of the image data, so that the capacity of the memory for storing the image data can be used effectively. Then, the comparing means compares the compressed data (compressed reference data) obtained by compressing the image data of the reference component with the compressed data obtained by compressing the image data of the remaining components. It is possible to determine whether or not the component image data is blank. For example,
When the detecting means detects blank data from the image data of the reference component, and the reference compressed data matches the compressed data of the remaining components, the blank determining means can determine that the sheet is blank.

That is, since the detection means detects whether or not the image data of the reference component is blank, it is possible to detect whether or not the other component is blank by comparing with the compressed data of other components. it can. Then, based on the detection result of the detection unit and the comparison result of the comparison unit, the blank page determination unit can determine whether the page is blank.

It is preferable that the reference component from which the detecting means detects blank page data be K component image data in advance. Since the image data of the K component is a component used in both the black-and-white image and the color image, by detecting the blank page of the image data of the K component, in the case of the black-and-white image, the image data of the other components is obtained. Makes it possible to make a blank page determination without making a comparison with the above, and the algorithm can be simplified.

According to a fourth aspect of the present invention, the image data of another component is detected, and the comparison means compares the image data of the comparison component based on the image data of the reference component and the other component with the remaining component image data. The image data of the components may be compared. Here, as the image data of the comparison component, data selected from the image data of the reference component or other components, or data obtained by synthesizing the selected data can be adopted.

Further, as in the invention according to claim 5,
The blank page determination means may perform blank page determination on one page or on a band obtained by dividing one page.
By dividing a page and performing blank page determination, it is possible to reduce the memory area for performing blank page determination.

The above-described blank sheet detecting device may be provided in an image recording device, may be provided in an image forming device, or may be provided in an image forming device.
The image reading device may be provided.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of an image recording apparatus to which a blank sheet detecting device of the present invention is applied.

In FIG. 1, a CPU 10 has a central function of various controls of the image recording apparatus, and is connected via a bus 12 to the following various circuit devices. The host interface circuit 14 is a circuit for interfacing with a higher-level device 16 such as a host computer.
The circuit is configured to receive data based on the 32C standard or the Centronics standard. Further, the host interface circuit 14 may be connected to a network and supplied with print data from a plurality of devices (for example, workstations) on the network (for example, Ethernet (registered trademark)). .

The RAM 18 is a working memory, and functions as a receiving buffer for temporarily storing data necessary for the image recording apparatus to perform various controls, print data input from the host interface circuit 14, and the like. I do. The RAM 18 includes a page memory 18a. R
The OM 20 is a memory for storing a program for controlling the image recording device. The compression / decompression unit 22 compresses one page of bitmap information and stores it in, for example, the RAM 18, and decompresses and outputs it to the recording unit interface circuit 24 at the time of printing.

The character pattern memory 26 is a so-called font memory, and stores character patterns for printing out. The recording unit interface circuit 24 converts the data expanded by the compression / expansion unit 22 into raster data and supplies the raster data to the recording unit 28,
An interface between the image recording apparatus and the recording unit 28 by transmitting and receiving various signals (synchronization pulse, recording unit status signal, operation command signal to the recording unit, and the like) to and from the recording unit 28. do. Note that the recording unit 28 is composed of, for example, a laser printer.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 2 and FIGS. 3 (A) and 3 (B). FIGS. 3A and 3B are diagrams showing the flow of image data.

In step 100 of FIG. 2, drawing information is input from the host computer 16 or the like via the host interface circuit 14. In step 102, a drawing process is performed to form image data (bitmap data).
For example, it is stored in the page memory 18a of the RAM 18.
In step 104, it is determined whether or not the input of the drawing information has been completed. When the determination is denied, the process returns to step 100, and the input of the drawing information is continued.

When the input of the drawing information is completed in step 104, the process proceeds to step 106, where the four components of one page (YMC
The creation of the image data of K) ends. Next, the routine proceeds to step 108, where only the K component of the four components (YMCK component) is detected as a blank sheet. The blank page detection can be performed using a known blank page detection such as searching for whether or not all bits are “0” indicating blank page (no image).

Then, the process proceeds to step 110, where the image data is read from the RAM 18 and then compressed and decompressed by the compression / decompression unit 22 in order to reduce the storage capacity of the image data.
(FIG. 3 (A), (B)), step 11
In step 112, the image data is temporarily stored in the RAM 18 as compressed data.
(Figures (A) and (B)).

Subsequently, in step 114, it is determined whether the four-component image data has been compressed by the compression / expansion unit 22 and the compressed data has been once stored in the RAM 18. If the determination is negative, the process proceeds to step 110 described above. That is, each component is sequentially compressed and stored in the RAM 18.

In step 116, it is determined whether or not the K component is blank based on the result of the blank detection of the K component in step 108. If the determination is affirmative, step 118
Then, the compressed data of the K component is compared with the compressed data of another component. Subsequently, in step 120, it is determined whether or not the comparison results in step 118 match, and if the determination is affirmative, the process proceeds to step 122, where the compressed data of the K component and the compressed data of each of the YMC components are compared. It is determined whether or not the comparison has been completed. If the determination is negative, the process returns to step 118 and is repeated until the comparison between the compressed data of each component of YMC and the compressed data of K component is completed.

When the comparison between the compressed data of all the YMC components and the compressed data of the K component is completed, and all the compressed data match, and the determination in step 122 is affirmative, step 1 is performed.
Then, the process proceeds to 24, and since the compressed data of the K component and the YMC component, which are blank pages, match, this page is determined to be blank.
The page determined to be blank may be stored by replacing the compressed data obtained by the compression processing with one page of white compressed data stored in the ROM 20. A flag indicating that one page is blank may be set in the RAM 18.

Next, when the recording operation starts, step 12
In step 6, the compressed data read from the RAM 18 is decompressed and the decompressed data is sent to the recording unit interface circuit 24 (FIGS. 3A and 3B). It should be noted that the compressed data of one page is blank,
2 may be read. In step 128,
After the decompressed data is converted into raster data by the recording unit interface circuit 24, it is sent to the recording unit 28 and recorded on paper. For printing on blank paper, the compressed data may be expanded and printed, or the printing process and the paper discharging process may be omitted and printing may not be performed.

On the other hand, if the determination in step 116 is negative, that is, if the K component is not blank, the process proceeds to step 130, where it is determined that the page is not blank because the K component is not blank. Then, the above step 12
Then, the program proceeds to step S6, where the decompression process is performed. If the determination in step 120 is negative, that is, if the compressed data of the K component and the compressed data of at least one of the YMC components do not match, the determination in step 130 is made in the same manner as described above. Then, since the components other than the K component are not blank, it is determined that the page is not blank, and the process proceeds to step 126, where the decompression process is performed, and the process proceeds to step 1.
At 28, a paper discharge process is performed.

According to the present embodiment, as shown in FIG.
Only the K component image data is compressed after performing the blank page detection processing, and the compressed data is held in the RAM 18. The other YMC component image data is compressed and stored in the RAM 18, and the blank page is detected. The blank page of one page is detected by comparing with the compressed data of the K component. That is, only the blank detection of the K component is performed, and the other components are compared with the detected K component.
Since blank page detection is performed, it is not necessary to perform blank page detection processing for all components. Therefore, blank page detection can be performed in a shorter time than when blank page detection processing is performed on all components as in the related art.

Further, by performing blank page detection of only the K component when performing blank page detection, it is not necessary to compare with other components in blank page detection in the case of a monochrome image.
It is possible to facilitate an algorithm when performing blank page detection.

In the above embodiment, after the drawing information is input from the host computer or the like via the host interface circuit 14 and all the drawing information is drawn,
Although the blank page detection of the K component is performed in step 108, the blank page detection of the K component may be performed when the rendering information is input and the rendering process is performed as shown in the flowchart of FIG. That is, in step 150, drawing information is input from a host computer or the like via the host interface circuit 14, and in step 152, drawing processing is performed and the image data (bitmap data) is stored in the page memory 18a of the RAM 18, for example. . At this time, in step 154, K of the four components (YMCK component)
Only blank components are detected, and it is determined in step 156 whether the input of drawing information has been completed as in step 104 of the above-described embodiment. If the determination is negative, the process returns to step 150 and the drawing is performed. The input of information may be continued, the blank detection of the K component may be continued, and if the determination in step 156 is affirmed, the process may proceed to step 158 to end the creation of one page of image data. Step 158 and subsequent steps are the same as those in the above-described embodiment except for the blank detection of the K component.

Next, another embodiment of the present invention will be described.
In this embodiment, one page image is divided into a plurality of band-like bands, and blank page detection is performed as in the above-described embodiment.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

In step 200, one band is subjected to drawing processing and stored in the page memory 18a of the RAM 18 in the form of image data. In step 202, a blank page detection process for the K component in the image data of the band subjected to the drawing process is performed, and the process proceeds to step 204. In step 204, the band subjected to the drawing process is compressed. In step 206, the compressed data of the band subjected to the compression process is held in the RAM 18. In step 208, it is determined whether the drawing processing, the K component blank page detection processing, and the compression processing have been completed for all the bands. If the determination is negative, the process returns to step 200 to continue the drawing process, the K component blank page detection process, and the compression process.

When the drawing process, the K component blank sheet detection process, and the compression process are completed for all the bands in step 208, the process proceeds to step 210, and the compression information of one band stored in the RAM 18 is extracted.

In step 212, it is determined whether or not the K component compressed data in the extracted one-band compression information is blank based on the result of blank page detection in step 202 described above.
If the determination is affirmative, the routine proceeds to step 214, where the compressed data of the K component and the compressed data of another component are compared. Subsequently, in step 218, step 216
It is determined whether or not the comparison results match each other. If the determination is affirmative, the process proceeds to step 218 to determine whether the comparison between the compressed data of the K component and the compressed data of each of the YMC components has been completed. Is done. If the determination is negative, the process returns to step 214 and is repeated until the comparison of all the YMC components and the K component is completed.

When the comparison between all the YMC component compressed data and the K component compressed data is completed, and all the compressed data match, and the determination in step 218 is affirmative, step 2
The band shifts to 20, and the band is determined to be blank because the compressed data of the K component and the YMC component, which are blank, match.
The band determined to be blank may be stored by replacing the compressed data obtained by the compression process with one-band white compressed data stored in the ROM 20. Further, a flag indicating that one band is blank may be set in the RAM 18.

On the other hand, if the determination in step 212 is negative, that is, if the K component is not blank, the process proceeds to step 228, and since the K component is not blank, it is determined that this band is not blank. . Step 21
If the determination of No. 6 is negative, that is, if the compressed data of the K component and the compressed data of at least one of the YMC components do not match, the process proceeds to step 228 as described above. Since the components other than the K component are not blank, it is determined that this band is not blank.

Subsequently, when the blank page determination of the band is performed as described above, the process proceeds to the printing process. Is made. In this decompression process, the decompression data for the blank band is stored in the ROM 2 in advance.
The decompression may be performed using the blank paper compression information stored in “0”. In step 224, it is determined whether or not the expansion processing of all the bands of one page has been completed. If the determination is negative, the process returns to step 210, and the processing from step 210 described above is repeated. If the determination in step 224 is affirmative, the process proceeds to step 226, where the decompressed data is converted into raster data by the recording unit interface circuit 24, sent to the recording unit 28, and recorded on paper.

According to this embodiment, even in the case of a technique for dividing one page image into a plurality of images and printing them, that is, in the case of banding, blank detection of only the K component is performed, and compression of the K component is performed for the other components. Since only comparison with data is performed, blank page detection can be performed at high speed.

Here, in the flowchart of FIG. 6, blank page detection is performed for all bands of the K component, and this is compared with the corresponding bands of other YMC components.
If the sizes of the bands are all the same, blank detection is performed for only one band for the K component, and the remaining K component bands and the remaining YMC component bands are the only K bands detected for the blank component. You may make it compare with the band of a component. By doing so, it is possible to further shorten the processing time and simplify the algorithm.

Note that the comparison between the compressed data of the K component and the compressed data of the other components detected in the blank pages in each of the above embodiments may be performed by software or hardware. By using hardware, the load on the CPU 10 can be reduced.

Further, in each of the above embodiments, only the K component is detected as a blank sheet. However, the present invention is not limited to this, and only the other components other than the K component may be detected as a blank sheet. One of the K component and the YMC color component may be detected as a blank page, or a plurality of YMCK components may be detected as a blank page. For example, when page information is created in the order of YMCK in order to print in the order of YMCK at the time of printing, a method of detecting a blank sheet using the first created color component other than the K component as a reference component is preferable. Is convenient. Also, YMC
When printing one page at a time in the order of K, the Y component and the M component are compared, and when the printing is completed, the Y component is printed.
After the component and the C component are compared and the M component is printed, the C component and the K component are compared. In the case where the comparison to be compared is sequentially changed as described above, it is more convenient to detect only a component other than the K component as a blank sheet.

The present invention is not limited to the image recording apparatus,
The present invention can be applied to an image forming apparatus or an image reading apparatus.

[0048]

As described above, according to the present invention, blank image detection of image data of a predetermined reference component among image data of a plurality of components for forming a color image is performed. Since the blank component is determined by comparing the components with the reference component detected as a blank component, the blank component can be detected in a short processing time without performing blank component detection of all components.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an operation of the image recording apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing a flow of image data.

FIG. 4 is a diagram showing an outline of the present invention.

FIG. 5 is a flowchart illustrating another operation of the image recording apparatus according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of an image recording apparatus that divides a page image into a plurality of images and prints the divided image.

[Explanation of symbols]

 Reference Signs List 10 CPU 12 bus 14 host interface circuit 18 RAM 20 ROM 22 compression / decompression unit 24 recording unit interface circuit 26 character pattern memory 28 recording unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/46 H04N 1/46 Z 5L096 F term (Reference) 2C087 AA15 AB05 AB08 BA03 BA07 BB10 BD10 BD40 2C187 AE11 2H027 DB01 DE07 EB04 EC06 EC20 EF06 FA28 FB05 FD08 ZA07 2H030 AD07 AD12 BB63 5C079 HB03 LA01 MA02 NA11 PA03 5L096 AA02 BA07 FA15 FA54 GA28

Claims (8)

[Claims] A detecting means for detecting blank paper data of image data of a predetermined reference component among image data of a plurality of components for forming a color image; A blank page detection device comprising: a comparison unit that compares image data; and a blank page determination unit that determines a blank page based on a detection result of the detection unit and a comparison result of the comparison unit. 2. The image processing apparatus according to claim 1, further comprising a compression unit configured to compress the image data of the reference component and the image data of the remaining components from which the white paper data is detected by the detection unit. The blank page detecting apparatus according to claim 1, wherein the compressed data of the compressed reference component is compared with the compressed data of the remaining components. 3. The image processing apparatus according to claim 1, wherein the detecting unit determines image data of a black (K) component as the reference component.
Or the blank sheet detection device according to claim 2. 4. The detecting means detects image data of another component, and the comparing means detects image data of a component for comparison based on the image data of the reference component and the image of the other component. The blank sheet detecting apparatus according to claim 1, wherein data is compared. 5. The method according to claim 1, wherein the blank sheet determination unit is configured to execute one page or one page.
The blank page detecting apparatus according to claim 1, wherein a blank page is determined for a band obtained by dividing a page. 6. An image recording apparatus comprising the blank sheet detecting device according to claim 1. Description: 7. An image forming apparatus comprising the blank sheet detecting device according to claim 1. Description: 8. An image reading device comprising the blank sheet detecting device according to claim 1. Description: