JP3085098B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for compressing image data input from an image reading device, storing the compressed data in a large-capacity memory, reading an arbitrary page, decompressing the page, and sending it to an image recording device. The present invention relates to a data compression device for forming an image of a unit.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and word processors, image information subjected to processing such as copying in office work has been diversified and increased in quantity. Along with this, in a copying machine that creates a copy of an original, not only a predetermined number of copies of the original but also a copy of the original by enlarging or reducing image information, various other functions are provided. Is being requested.
For example, an electronic RDH (Electron RDH) that performs a copying operation electronically in a state in which a plurality of originals are sorted by an arbitrary number of copies.
ic Recirculating Document Handler) function and copy many originals on both sides of the recording paper, with each page split into two pages, so that the original images become a single booklet in page order There is a bookbinding function for editing and copying images.

As a copying machine capable of realizing this kind of function, there is, for example, the following digital copying machine. In other words, this digital copier transfers an original to an ADF (Auto Document Fe
eder), the document is automatically conveyed to the platen of the copier automatically by the ADF, and the image of the document is read by the scanner, converted into a digital signal, and stored once. The stored image information is read out, an image is recorded by an IOT (Image Output Terminal), and a function of copying a document is realized. In such a digital copying machine, when storing image information of a document read by a scanner, the amount of information is reduced by compressing a redundant portion of the image information of the document so that more image information can be stored. An image storage device for storing image information is used.

In order to realize, for example, a bookbinding function in the above-described digital copying machine, it is necessary to temporarily store all input documents and to control the output image order so that the output documents are arranged in a page order and to output the images. . However, since the capacity of a storage device (such as a hard disk) may become insufficient during accumulation, various techniques have been proposed to continue the image output process even in such a case. For example, in Japanese Patent Application Laid-Open No. 6-62258, if the memory capacity of the storage device becomes insufficient during storage, the encoding condition of the already stored image data is changed (in a direction to reduce the memory capacity), and the necessary area becomes smaller. A technique is disclosed in which the storage process is continued when it is secured.

That is, according to the technique disclosed in this publication, a plurality of quantization thresholds K (K = K
1, 2,..., N), and the smaller the K, the larger the data amount after compression. At the beginning of the process, the quantization threshold value 1 is applied, and the image data is sequentially accumulated. Eventually, when the storage capacity becomes insufficient, the already read image data is recompressed based on the quantization threshold 2, and after the necessary storage capacity is secured, the storage processing is continued. Here, the quantization threshold value 2 is applied to newly stored image data from the beginning. Thereafter, similarly, each time the storage capacity becomes insufficient again, the quantization threshold values 3,..., N are sequentially applied.

[0006]

However, according to the above-mentioned prior art, re-compression processing may be performed a large number of times before all image data are accumulated. For example, assuming that the quantization threshold L (1 <L ≦ N) is finally selected for the image data at the top, the image data includes the quantization threshold 1, the quantization threshold 2,
... This means that the compression processing has been performed L times in the order of the quantization threshold L. Therefore, a large amount of time is spent on the compression processing time until the accumulation of all image data is completed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to provide an image processing apparatus capable of quickly storing image data.

[0008]

According to a first aspect of the present invention, there is provided a target reduction rate determining means for determining a target reduction rate of a data amount of image data; Input reduction means for inputting image data and reducing the data amount, reduction rate measurement means for measuring a reduction rate of the data amount of the image data reduced by the input reduction means, and measurement by the reduction rate measurement means And a next input reduction unit for inputting the predetermined unit amount of the image data to be reduced next and reducing the image data at a higher reduction ratio than the input reduction unit when the reduced ratio is lower than the target reduction ratio. And

According to a second aspect of the present invention, there is provided a target reduction amount determining means for determining a target reduction amount of the data amount of the predetermined unit amount of image data, and a predetermined unit amount of the image data, An input reduction unit configured to reduce a data amount, a reduction amount measurement unit configured to measure a reduction amount of a data amount of the image data of a predetermined unit amount reduced by the input reduction unit,
If the reduction amount measured by the reduction amount measuring unit is smaller than the target reduction amount, the next input is to input the image data of a predetermined unit amount to be reduced next and to reduce by a larger reduction amount than the input reducing unit. And reducing means.

According to a third aspect of the present invention, there is provided an input reducing means for inputting image data and reducing the data amount at a first reduction rate, and storing the image data after reducing the data amount. Means, overflow detection means for detecting overflow of the storage means, and reduction of the data amount by the input reduction means even after detection of the overflow by the overflow detection means to determine the total data amount to be stored in the storage means. Measuring means for measuring, reduction rate determining means for determining a second reduction rate based on the amount of data measured by the measuring means and the capacity of the storage means, and re-inputting image data to determine the data amount And a re-input reduction unit for reducing at a second reduction rate.

[0011]

According to the configuration of the first aspect, first, the target reduction rate determining means determines the target reduction rate of the data amount of the image data. Next, the input reducing means inputs a predetermined unit amount of image data and reduces the data amount. Next, the reduction rate measuring means measures the reduction rate of the data amount of the image data reduced by the input reducing means. When the reduction rate measured by the reduction rate measurement means is lower than the target reduction rate, the next input reduction means inputs the predetermined unit amount of the image data to be reduced next, and outputs the data amount at a higher reduction rate than the input reduction means. Reduce. Therefore, even when the reduction rate of any of the image data does not reach the target reduction rate, the reduction rate obtained by integrating all the image data is a value close to the average value of each target reduction rate.

According to the second aspect of the present invention, first, the target reduction amount determining means determines the target reduction amount of the image data. Next, the input reducing means inputs a predetermined unit amount of image data and reduces the data amount. next,
The reduction amount measuring unit measures the reduction amount of the data amount of the image data reduced by the input reduction unit. When the reduction amount measured by the reduction amount measurement unit is lower than the target reduction amount, the next input reduction unit inputs the image data of a predetermined unit amount to be reduced next and reduces the image data by a reduction amount larger than the input reduction unit. . Therefore, even when the reduction amount of any of the image data does not reach the target reduction amount, the reduction amount obtained by integrating all the image data is a value close to the total value of the respective target reduction amounts.

According to the third aspect of the present invention, when the input reduction unit inputs image data and reduces the data amount at the first reduction rate, the reduced image data is stored in the storage unit. . At this time, the overflow detecting means detects the occurrence of overflow in the storage means.
When the overflow is detected by the overflow detecting means, the measuring means continues to reduce the data amount by the input reducing means, thereby measuring the total data amount to be stored in the storage means. Next, the reduction rate determining means determines a second reduction rate based on the data amount measured by the measuring means and the capacity of the storage means. Then, the re-input reduction unit re-inputs the image data, and reduces the data amount at the second reduction rate.

[0014]

【Example】

A. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of the image processing apparatus according to the present embodiment. In FIG. 1, reference numeral 1 denotes an input device for reading an original using a CCD sensor and inputting image data, and is constituted by a scanner or the like. 2 is m [bit /
Is a gradation converter that performs a process of lowering the gradation of image data of [pixel] to image data of n [bit / pixel] (m, n: a natural number satisfying m> n), for example, sent from an input device. Data of 8 [bit / pixel] is converted to 4 [bit / pixel] or 1
The output is performed with the gradation dropped to the data of [bit / pixel]. 3
Is a storage amount control device provided with a unit storage amount determining means for determining the storage amount per unit and a storage amount measuring means for measuring the storage data amount. Reference numeral 4 denotes a compressor for compressing image data.

The type of the compressor is not limited by the present invention, but the compression ratio can be improved by lowering the gradation so that the same data continues to improve the compression ratio.
Encoding or predictive encoding is preferred. Reference numeral 5 denotes a storage device for storing image data, which is constituted by a hard disk, a DRAM memory, or the like. Reference numeral 6 denotes a decompressor for decompressing the compressed code data. Reference numeral 7 denotes an output device, which controls on / off of a laser beam for each pixel based on binary image data generated from image data to form a halftone image. Reference numeral 8 denotes a control device that activates the compressor 4 and the decompressor 6 or generates a control signal such as an address to the storage device 5.

The gradation converter 2 and the storage amount control device 3 of FIG. 1 will be described in detail with reference to FIGS. 2 and 3, respectively. First, in FIG. 2, reference numeral 9 denotes 8 bi for gradation conversion of 8 [bit / pixel] image data into 4 [bit / pixel] image data.
The t → 4 bit converter 10 converts the gradation of 8 [bit / pixel] image data to 2 [bit / pixel] image data.
A bit → 2 bit converter 11 is an 8 bit → 1 bit converter for performing gradation conversion of 8 [bit / pixel] image data to 1 [bit / pixel] image data.

As a method of gradation conversion, for example, 8 bi
8 bits (256 gradations) when converting from t to 2 bits
Is generally divided into four by three thresholds and simply converted to 2-bit (four gradation) data as shown below. 0 to 63 gradations → 00 64 to 127 gradations → 01 128 to 191 gradations → 10 192 to 255 gradations → 11 However, it goes without saying that the gradation conversion method is not limited to the above.

Reference numeral 12 denotes a selector, whose input terminals a,
The image data output from each of the converters 9, 10, and 11 is supplied to b and c, respectively.
Pixel] is supplied. The selector 12 selects image data of any one of the input terminals based on the supplied switching signal, and supplies the selected image data to the compressor 4. Reference numeral 13 denotes a threshold comparison unit, and reference numeral 14 denotes a gradation conversion control unit, which determines the above-described switching signal. The details will be described later.

Next, in FIG. 3, reference numeral 15 denotes a UI (User I
This is configured by a keyboard or a touch panel, and enables the user to set a predicted value of the unit data amount. Here, the unit data amount prediction value is an approximate value of the data amount (compression code data amount) per one page of the document, and a default value is stored in the control device 8 in advance. The default value is set to a data amount obtained when a predetermined standard original composed of only characters is compressed by the compressor 4. That is,
If the user does not particularly specify the predicted unit data amount, the default value is used as the predicted unit data amount. On the other hand, the default value may be inappropriate depending on the type of the original (for example, there are many image images). In such a case, the user may set an arbitrary unit data amount prediction value.

Reference numeral 17 denotes a storage amount measuring means, which receives the compression code data amount of each page from the compressor 4 and sequentially adds them to calculate a total storage data amount y. Further, the accumulation amount measuring means 17 counts the number of compressed code data (corresponding to the number of originals) and outputs the result as the number x of already input pages. Reference numeral 16 denotes a unit storage amount setting unit, which divides the storage capacity N of the storage device 5 (this value is a known value according to the physical configuration of the storage device 5) by the unit data amount prediction value to obtain a document. The total number of pages M is calculated.

For example, if the storage capacity N = 100 MByte,
The compression rate of the standard A4 document of the compressor 4 is 8 (data is 1/8
Is compressed, the A4 before compression is assumed.
Since the amount of data per page of the original is about 8 MByte, the amount of compressed code data per page of the A4 original is 1
MByte. Therefore, the compressed code data of the A4 document can be stored in this storage device for 100 sheets, so that M = 10
It becomes 0 (page). As described above, the total number of pages is uniquely determined by the storage capacity N, the compression ratio of the compressor 4, and the data amount of one page of the input document.

Further, the unit accumulation amount setting means 16 outputs threshold values L ₁ , L ₂ , L ₃ based on the number x of already input pages. These thresholds are functions of the number of input pages x,
This is as shown in the following equation (1) and FIG. L ₁ = (N / M) · x [M byte] L ₂ = (N / M) · x + i [M byte] L ₃ = (N / M) · x + j [M byte] (1)

In the above equation, i and j are predetermined offset values, which are appropriately designated by the user via the UI 15. By the way, when the possible value of the total accumulated data amount y is divided into a plurality of regions bounded by the thresholds L ₁ , L ₂ , L ₃ , the total accumulated data amount y becomes It will belong to either. Area A: y ≦ L ₁ Area B: L ₁ <y ≦ L ₂ Area C: L ₂ <y ≦ L ₃ Area D: L ₃ <y ... Equation (2)

Returning to FIG. 2, the threshold comparing means 13 receives the thresholds L ₁ , L ₂ , L ₃ from the unit storage amount setting means 16 and the total stored data amount y from the storage amount measuring means 17, It is determined which of the areas A to D the total accumulated data amount y belongs to. And the gradation conversion control means 1
4, each converter 9, 10,
An appropriate supply of an enable signal to the selector 11 and a supply of a switching signal to the selector 12. Thus, the gradation of the image data is determined for each processing target page. The details will be described separately for each case.

First, when the judgment result of the threshold value comparing means 13 is "area A", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal d is selected. Also, an 8 bit → 4 bit converter 9, 8 bit
→ 2-bit converter 10, 8 bit → 1-bit converter 11
Are negated by the gradation conversion control means 14. Therefore, when the image data of the input document of the next page is supplied later, this image data is
Is supplied to the compressor 4 via the As described above, when the determination result relating to the current accumulated data amount is in the “region A”, the image data of the input document of the next page is not subjected to the gradation conversion, and the image quality of the input document is maintained. 4 is output.

When the determination result is "area B", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal a is selected. Further, the gradation conversion control means 14 asserts only the enable signal of the 8-bit to 4-bit converter 9, and negates the enable signal of the 8-bit to 2-bit converter 10 and the 8-bit to 1-bit converter 11. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The data amount is reduced via the it → 4 bit converter 9,
Thereafter, it is supplied to the compressor 4 via the input terminal a. As described above, the determination result regarding the current accumulated data amount is “area B”
, The image data of the input document of the next page is 4
The image data is converted into [bit / pixel] image data and output to the compressor 4.

When the determination result is "area C", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal b is selected. Further, the gradation conversion control means 14 is provided with an 8-bit to 2-bit converter 10.
Assert only the enable signal of 8 bits → 4 bits
The enable signal of the converter 9, 8 bit → 1 bit converter 11 is negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The amount of data is reduced via the it → 2 bit converter 10 and thereafter supplied to the compressor 4 via the input terminal b. As described above, when the determination result regarding the current accumulated data amount is in “area C”, the image data of the input document of the next page is
The image data is converted into image data of 2 [bit / pixel] and output to the compressor 4.

When the determination result is "area D", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal c is selected. Further, the gradation conversion control means 14 controls the 8 bit → 1 bit converter 11
Assert only the enable signal of 8 bits → 4 bits
The enable signal of the converter 9, 8 bit → 2 bit converter 10 is negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The data amount is reduced via the it → 1 bit converter 11 and thereafter supplied to the compressor 4 via the input terminal c. As described above, when the determination result regarding the current accumulated data amount is in “area D”, the image data of the input document of the next page is
The image data is converted into 1 [bit / pixel] image data and output to the compressor 4.

As described above, image data is compressed while the degree of gradation conversion is changed for the input document of the next page based on the total amount of compressed code data stored up to the present time. Therefore, for example, when predictive coding is used for the compressor 4, 4 [bit / pixel] and 4 [b] are used instead of 8 [bit / pixel].
Since the same data is more likely to appear in 2 [bit / pixel] than in [it / pixel] and 1 [bit / pixel] than in 2 [bit / pixel], the amount of data is also reduced when encoding. Needless to say, the compression method of the compressor 4 is not limited to the predictive coding method.

B. Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing a basic configuration of the copying machine of the present embodiment. In FIG. 5, an ADF (automatic document feeder)
Reference numeral 100 denotes a device for automatically sending a document to the image input means 101. The image input means 101 comprises, for example, a document reading device for inputting image data. The tone number conversion means 102 converts the number of tones of the read image, and converts the number of bits such as converting an image read at 8 bits per pixel into a 4 bit image. Things.

The resolution conversion means 103 converts the resolution of the read image. For example, a thinning-out or reduction process such as converting an image read at 400 samples per inch into an image read at 200 samples. I do. The compression unit 104 performs a compression process on the supplied image data using, for example, an adaptive prediction coding method. The data amount detection unit 105 detects the amount of compressed image data, and the page buffer 106 stores one or more pages of compressed image data compressed by the image compression unit 104.

The storage means 108 stores the compressed image data stored in the page buffer, and uses, for example, a magnetic disk, MO, or the like. This storage means 108
Has a capacity capable of accumulating output data (compressed image data) of the image compression unit 104 for at least an average compression ratio for a predetermined input page. Storage control means 10
Reference numeral 7 denotes an input / output of the storage means 108, and SC
An SI interface or the like is used. Image expansion means 1
Reference numeral 09 is for decompressing the compressed image data and restoring the original image data. The resolution conversion unit 110 returns the image data whose resolution has been converted by the resolution conversion unit 103 to data of the original resolution. Further, the gradation number conversion means
Numeral 11 is for returning the image data whose gradation number has been converted by the gradation number conversion means 102 to image data of the original gradation number.
The recording means 112 is for recording image data.
The overall control unit 113 controls other components.

In the above configuration, a mode in which processing cannot be performed until all input documents have been stored (booklet creation, etc.)
Will be described. In the figure, an input document is set on an automatic document feeder ADF 100 and is sequentially conveyed to an image input unit 101 and read. First, when the first page of the document is read by the image input unit 101,
The contents are output from the image input means 101 as image data. When this image data is supplied to the gradation number conversion means 102, the gradation number of the image data is converted to a predetermined value. Further, the converted image data is supplied to the resolution conversion unit 1.
03, the resolution of the image data is converted to a predetermined value.

Next, the image data output from the resolution conversion means 103 is compressed by the image compression means 104. Next, the compressed image data is sent to the data amount detecting means 1.
The data amount is stored in the page buffer 106 via the data buffer 05, and at this time, the data amount of the image data is measured by the data amount detection unit 105. When the compressed data corresponding to one page of the document is stored in the page buffer 106, the compressed data is transferred from the page buffer to the storage unit 108, where the compressed data is stored. At this time, the next document is read by the ADF 100, and the page buffer 10 is sequentially passed through the image input unit 101 to the data amount detection unit 105.
6 is stored. Then, all input documents are compressed,
The above operation is repeated until the data is stored in the storage unit 108.

When all the input documents are stored in the storage means 108, the operation mode of the copying machine is set to the copy mode by the operation terminal (not shown). Thereby, the storage means 1
An arbitrary page is read from the compressed data stored in 08 and transferred to the page buffer 106. Next, the compressed data is transferred from the page buffer 106 to the decompression means 109.
And the compressed image data is restored from the compressed data. The restored image data is supplied to the resolution conversion unit 11.
The image data is sequentially converted to image data having a predetermined resolution and a predetermined number of gradations through 0 and gradation number conversion means 111. The image data output from the gradation number conversion means 111 is supplied to the recording means 112, where the contents of the image data are recorded on paper.

Next, the detailed operation of this embodiment will be described with reference to FIGS. Note that these figures show the overall control means 11.
3 is a flowchart of a control program stored in the control program No. 3; First, the operator sets an input document on the ADF 100, and sets a copy mode and the number of copies using an operation terminal (not shown). At this time, the copy mode is set to the booklet creation mode. Next, the general control means 11
In 3, the control program shown in FIGS. When the process is started in FIG.
At 0, the process waits until a copy start button (not shown) is pressed. When the copy start button is pressed, the process proceeds to step S201, and an image input command is transmitted from the overall control unit 113 to the ADF 100.

When the above command is supplied, the ADF 100 conveys the first page of the document to the image input means 101. Thus, the content of the first page of the document is read by the image input unit 101 and output as image data. next,
When the process proceeds to step S202, the image input unit 101
Is supplied to the gradation number conversion means 102, where the gradation number of the image data is converted into a predetermined value. Further, the converted image data is supplied to the resolution conversion means 103, where the resolution of the image data is converted to a predetermined value. Then, the image data output from the resolution conversion unit 103 is compressed by the image compression unit 104.

Next, when the process proceeds to step S203,
The compressed image data is supplied to the data amount detection unit 105, where the data amount of the compressed image data is measured. Then, the measured data amount is stored in the overall control unit 113 for each page. Next, the process proceeds to step S2.
In step 04, compressed data equivalent to one page of the document whose data amount has been measured is stored in the page buffer 106. Next, in step S205, the page buffer 1
From 06, compressed data corresponding to one page of the original is transferred to the storage means 108, and the compressed data is stored on a hard disk (magnetic disk) in the storage means 108.

Now, while the data is being stored in the hard disk, the processing is executed by the overall control means 113 in step S2.
Proceed to 07. Here, whether there is a memory overflow,
That is, it is detected whether the storage capacity of the hard disk is sufficient. Here, if no overflow has occurred, “NO” is determined, and the process proceeds to step S207.
In step S207, a search is performed to determine whether or not the original remains in ADF 100. If the document remains, the process returns to step S201, and the loop of steps S201 to S207 is repeated a number of times corresponding to the number of documents.

Then, if the processing proceeds to step S207 after the storage processing for the last page of the document is completed, “YES” is determined here, and the processing proceeds to step S208. In step S208, an arbitrary page is read from the hard disk and stored in the page buffer 106. Then, when the process proceeds to step S209,
The compressed image data is decompressed, gradation-converted, and resolution-converted according to predetermined decompression, gradation, and resolution parameters, and a predetermined number of recordings are recorded by the recording apparatus, and the process ends.

When the image data of the original is large, the hard disk may overflow during the storage of the image data on the hard disk. In such a case, in step S206, "YE
Is determined to be "S", the process proceeds to step S210, and the storage operation to the hard disk is interrupted. But,
The input of the image data of the next document via the ADF 100 and the image input unit 101 is continued. Next, the processing of steps S211 and S212 is performed. Here, the same processing as in steps S202 and S203 is performed. That is, the input image data is subjected to gradation, resolution, and compression processing using predetermined gradation, resolution, and compression parameters, and the amount of data after compression is measured and stored in the overall control unit 113.

Next, when the process proceeds to step S213,
It is determined whether the compressed data amount has been calculated for all of the input documents (S213), and if not completed (S2).
Returning to 10), image input is continuously performed. Therefore, steps S210 to S2 are performed a number of times corresponding to the number of remaining documents.
The loop of 13 is repeated, and the compressed image data of each page is stored in the overall control unit 113. And
If the process proceeds to step S213 after the data amount after compression has been calculated for all the originals, “YES” is determined here, and the process proceeds to step S214.

In step S214, the amount of compressed data for each page is summed up, thereby calculating the total amount of compressed data of the input image. Next, the process proceeds to step S
In step 215, a reduction target value (data amount to be reduced) is calculated from the known hard disk capacity and the total compressed data amount. Next, when the process proceeds to step S216, the gradation, resolution, and compression parameter for each page at the time of re-input are determined based on the reduction target value and the amount of compressed data for each page stored in the overall control unit. Is done.

Here, the processing in step S216 will be described in detail. First, as described above, the overall control unit 113 stores the data amount in page units for all pages (S203, S21).
2). Therefore, in this step, the data amount of each page is determined for each page by a predetermined gradation, resolution, and how much the data amount is compared with that before compression processing. That is, the compression ratio is obtained. Then, for each page, FIG.
Is activated.

First, when the subroutine of FIG. 8 is started for any page, in step S227,
It is determined whether the compression ratio of the target page is 3 or less. If the compression ratio is 3 or less, the process proceeds to step S230. Here, the resolution parameter at the time of re-input is determined according to the reduction target value based on the column A in FIG. On the other hand, if the compression ratio is 3 or more, the process proceeds to step S228, and it is determined whether the compression ratio is 3 or more and 8 or less. If the compression ratio is 3 or more and 8 or less, both the gradation parameter and the resolution parameter at the time of re-input are determined based on the column C in FIG. 9 (S231). If the compression ratio is 8 or more, only the gradation parameters at the time of re-input are determined (S229).

The contents of the processing in steps S229 to S231 will be described in more detail with reference to FIG.
Although details will be described later, in the present embodiment, when the hard disk overflows, the input processing of the original image data is performed again. Hereinafter, this is referred to as “re-input”. When re-inputting the image data, if the same parameters (gradation, resolution, etc.) are used as before, the hard disk overflows again. Therefore, it is necessary to change these parameters so as to reduce the data amount. In this embodiment,
The parameters to be changed are the gradation and the resolution, and which of these is to be changed and how much to change are defined by the respective columns in FIG.

First, column A in the figure is a column referred to when only the resolution is changed, and is referred to in step S230. Column B is a table that is referred to when only the gradation parameter is changed, and is referred to in step S229. Column C is a table that is referred to when changing both the resolution and the gradation parameter, and is referred to in S231.
First, in the uppermost column of FIG. 9, the “reduction target value” is the amount of data that must be reduced obtained by the overall control unit, and is calculated in S 214 and S 215. Here, the reduction amount 0 indicates that the reduction is unnecessary, and indicates that the image reading is set to have the highest image quality in this apparatus.

"~ 1" indicates that the reduction target value is 1 MB or less. Next, in the columns A and C in the same figure, the “resolution” is the number of samples per unit length (1/400 inch). That is, a resolution of "1" means that the data was read with 400 samples per inch. Also, 0.75 means that the data read at 400 samples per inch is converted into 3/4 samples, and the number of data is reduced to 300 samples per inch. The image becomes coarse. Also, in the columns B and C in FIG.
Pixel] ”is b for performing gradation expression per pixel.
The number of bits means that the greater the number of bits, the greater the number of tones and the richer halftone reproduction of a photographic document or the like. In this embodiment, from 8 bits (256 gradations) to 1 bit (2
(Value conversion).

The predetermined gradation and resolution (S202) in the first image reading process are set so that the reading becomes the highest image quality. The setting when the reduction target value in this table 110 is 0 corresponds to this. At this time, the resolution is 1 (400 / inch) and the number of gradations is 8 [bit /
Pixel]. Next, a case where the resolution parameter is changed in S230 will be described. Assuming that the reduction target value is calculated to be, for example, 4.5 MB in S214 and S215, the resolution is changed to 0.5 in the column of “〜5” in the section of the reduction target value in the column of FIG. 9A. Next, a case where the gradation parameter is changed in S229 will be described. Assuming that the reduction target value is calculated to be, for example, 4.5 MB in S214 and S215, the gradation is 8 [bi] in the column of “〜5” in the section of the reduction target value in the column of FIG. 9B.
t / pixel] to 2 [bit / pixel].

Next, the case where both the resolution and the gradation parameter are changed in S231 will be described. Assuming that the reduction target value is calculated to be, for example, 4.5 MB in S214 and S215, “に て” is set in the section of the reduction target value in the column of FIG. 9C.
5 ”, the resolution was changed to 0.66 and the gradation was changed to 8
[bit / pixel] is changed to 4 [bit / pixel]. As described above, the resolution and gradation parameters are changed on a page-by-page basis according to the amount of compressed data and the reduced capacity of one page, and are set so that overflow does not occur at the time of re-input.

The compression method used here is, for example, an adaptive predictive coding method. In this method, the compression ratio changes depending on the type of the input document. A document having a good compression ratio is a binary image document such as a character, and a document having a compression ratio between them can be estimated to be a document having a mixture of halftone and binary images. As for information reduction of a halftone original, image quality degradation is less when the resolution parameter is changed than when the gradation is changed. Also, as for information reduction of a binary image original such as a character, changing the gradation parameter rather than the resolution causes less deterioration in image quality. Therefore, FIG. 8 shows a configuration in which the type of the input document is estimated based on the compression ratio of one page, and a parameter for information reduction with little deterioration in image quality is selected and changed.

When the processing of steps S216 to S231 is performed on all pages of the original and the resolution or reduction target value at the time of re-input is determined, the processing returns to the main routine (FIGS. 6 and 7), and Proceed to S217. It is assumed that the originals of all pages have been set on the ADF 100 by then. In step S217, the image data of the first page of the document is read via the ADF 100. Next, when the process proceeds to step S218, based on the parameters of the first page of the original set in step S216 (and the subroutine in FIG. 8), the gradation characteristics (gradation bit / pixel) of the image data and The resolution is converted. Specifically, the tone number conversion means 1
02 designates the gradation characteristics, the resolution conversion means 103 designates the resolution, and the image compression means 104 designates the compression ratio, by the overall control means 113. Then, the re-input image data is sequentially converted through these means.

Next, when the process proceeds to step S219,
The compressed data amount of the first page of the document is measured via the data amount detecting means 105 and stored in the overall control means 113. Next, when the process proceeds to step S220, the compressed data is stored in the page buffer. The compressed data stored in the page buffer is transferred to a hard disk (magnetic disk) and stored in the next step S221. Next, when the process proceeds to step S213, it is determined whether or not all input documents have been compressed and accumulated. If the accumulation has not been completed, the process returns to step S217. Thus, steps S217 to S217 are performed by the number of times corresponding to the number of originals.
When the loop of 222 is repeated and the image data of all the documents is accumulated, the process proceeds to step S223.

In step S223, an arbitrary page is read from the hard disk and the page buffer 1
06 is stored. Then, in step S224, the compressed image data is expanded, converted in gradation, and converted in resolution using predetermined expansion, gradation, and resolution parameters. here,
This compressed data is the compressed data in which the gradation, resolution, and compression parameters have been set for each page in step S218. Accordingly, in order to restore the compressed data, the image data is converted into the original image data even if the expansion, gradation, and resolution parameters are set in page units corresponding to the settings in step S218. And step S
In 225, a predetermined number of the converted image data are recorded by the recording device, and the process ends.

C. Modifications The present invention is not limited to the above-described embodiments, and various modifications are possible, for example, as follows. (Modification) In the first embodiment, the default value of the unit data amount prediction value is set based on a predetermined standard original composed of only characters, but a plurality of default values may be provided. For example, the data amount per page may be obtained for a standard character document and an image document, and these may be stored in the control device 8 as default values of the character document and the image document. In such cases,
When the user sets the number of originals for each of the text original and the image original, the storage capacity N [M byte] can be set more accurately.

(Modification) In the first embodiment, FIG.
Although the threshold values L ₁ , L ₂ , and L ₃ are set as shown in FIG. For example, thresholds L ₁ and L ₄ may be set as shown in FIG. Threshold L ₁ in the figure is similar to that of FIG. (A), the threshold L ₄ are represented by the following equation. L ₄ = (N−k) / M · x + k (unit: MByt)
e) In the above equation, the threshold L ₄ are offset value k (Unit: MByte) is set, the data amount per one page can be defined from FIG as (N-k) / M. As described above, the threshold L ₄ is uniquely determined when k is determined.
The user may calculate the value of N−k in advance and input the value from the UI 15.

By dividing the possible value of the total accumulated data amount y into a plurality of regions bounded by the thresholds L ₁ and L ₄ , the total accumulated data amount y becomes three regions of the following formula (3). It will belong to either. Area A: y ≦ L ₁ Area B: L ₁ <y ≦ L ₄ Area C: L ₄ <y Equation (3)

As described above, the unit accumulation amount setting means 16 sets a plurality of threshold functions. Then, based on the information of the thresholds L ₁ and L ₄ sent from the unit accumulation amount setting means 16 and the number x of already input pages and the total accumulated data amount y at the present time sent from the accumulation amount measuring means 17. In the threshold comparing means 13, the total accumulated data amount y is equal to the area A,
It is determined which of B and C exists. As in FIG. 3A, this determination is made for each page of the input document. If the result of the determination is that the current accumulated data amount is in “area A”, the gradation conversion control means 14 outputs a switching signal designating the input terminal d to the selector 12.

The gradation conversion control means 14 has an 8-bit
→ 4-bit converter 9, 8-bit → 2-bit converter 10,
Any of the enable signals of the 8-bit to 1-bit converter 11 is negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is output to the compressor 4 via the input end d. As described above, when the determination result relating to the current accumulated data amount is in the “region A”, the image data of the input document of the next page is not subjected to the gradation conversion, and the image quality of the input document is maintained. 4 is output.

If the determination result is "area B", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal a is selected. Further, the gradation conversion control means 14 asserts only the enable signal of the 8-bit to 4-bit converter 9, and negates the enable signal of the 8-bit to 2-bit converter 10 and the 8-bit to 1-bit converter 11. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The data amount is reduced via the it → 4 bit converter 9,
Thereafter, it is supplied to the compressor 4 via the input terminal a. As described above, the determination result regarding the current accumulated data amount is “area B”
, The image data of the input document of the next page is 4
The image data is converted into [bit / pixel] image data and output to the compressor 4.

When the determination result is "area C", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal b is selected. Further, the gradation conversion control means 14 is provided with an 8-bit to 2-bit converter 10.
Assert only the enable signal of 8 bits → 4 bits
The enable signal of the converter 9, 8 bit → 1 bit converter 11 is negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The amount of data is reduced via the it → 2 bit converter 10 and thereafter supplied to the compressor 4 via the input terminal b. As described above, when the determination result regarding the current accumulated data amount is in “area C”, the image data of the input document of the next page is
The image data is converted into image data of 2 [bit / pixel] and output to the compressor 4.

By controlling as described above, the degree of gradation conversion for the input document of the next page is changed according to the total amount of compressed code data up to the present time, as in the first embodiment. While the image data is compressed, the data amount can be reduced. Further, in the case of FIG. 4A, the degree of gradation conversion is low when the total storage amount y is still in the region B or the region C when the total storage amount y approaches the storage capacity N. in it may not be able to accumulate the input document full page occurs because, (B) by setting the threshold value L ₄ as a function of, as far as possible when the total accumulated amount y is approached to the storage capacity N Since compression and accumulation are performed with the lowest gradation, all pages of the input document can be accumulated.

(Modification) Each threshold value may be set as shown in FIG. FIG. 10C shows a case where the number of input document pages is doubled (2M pages) in a system including a storage device having a storage capacity of N (MBytes) as in FIGS. is there. The threshold function L ₅ in this case, L ₅ = N / 2M (Unit: MByte) is set at. Thus the total accumulated data amount y is a "y ≦ L _5" as the boundary threshold function L ₅ regions A and "y
> L ₅ ”. Fig (A), similarly (B), and the information of the function L ₅ sent from the unit storage amount setting means 16, and the already input the number of pages x to date sent from the accumulation amount measuring means 17 From the total stored data amount y, the threshold comparing unit 13 determines whether the current total stored data amount y exists in the area A or the area B.

This determination is made for each page of the input document, as in the cases of FIGS. As a result of the judgment,
When the current accumulated data amount is in the “region A”, the gradation conversion control means 14 outputs a switching signal designating the input terminal d to the selector 12. Further, the gradation conversion control means 14
Is an 8 bit → 4 bit converter 9, 8 bit → 2 bit
All the enable signals of the converter 10 and the 8-bit → 1 bit converter 11 are negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is output to the compressor 4 via the input end d. As described above, when the determination result related to the current accumulated data amount is in “area A”, the image data of the input document of the next page is
While the input image quality is maintained without gradation conversion,
Output to the compressor 4.

When the result of the determination is "region B", the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal a is selected. Further, the gradation conversion control means 14 asserts only the enable signal of the 8-bit to 4-bit converter 9, and negates the enable signal of the 8-bit to 2-bit converter 10 and the 8-bit to 1-bit converter 11. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The data amount is reduced via the it → 4 bit converter 9,
Thereafter, it is supplied to the compressor 4 via the input terminal a. As described above, the determination result regarding the current accumulated data amount is “area B”
, The image data of the input document of the next page is 4
The image data is converted into [bit / pixel] image data and output to the compressor 4.

By controlling as described above, the gradation conversion is performed on the input document of the next page according to the total accumulated amount of the compressed code data up to the present time, as in the cases of FIGS. The amount of data can be reduced by compressing the image while changing the degree of the image. Furthermore, FIG.
When threshold function L ₅ of 1/2 the amount of data per page is compared with a threshold value L ₁ in FIG. (A) or (B)
Therefore, even if the same number of originals are input in the same order as in the case of FIGS. (A) and (B), the number of pages to be converted is (A) or ( B). Therefore, although the image quality deteriorates accordingly, the number of document pages that can be stored can be increased.

[0067] (Modification) Similarly, the threshold may be set as shown in FIG. 4 (D). FIG. 3D shows the storage capacity of FIG.
N (MByte) as in (C). In a system equipped with a storage device, the number of input original pages is reduced by half (M
/ 2 pages). The threshold function L in this case
₆ is set by L ₆ = 2N / M (unit: MByte). As a result, the total accumulated data amount y belongs to either the region A where “y ≦ L ₆ ” or the region B where “y> L ₆ ” with the threshold function L ₆ as a boundary. As in the case of FIG. (A) ~ (C), and information of the threshold function L ₆ sent from the unit storage amount setting means 16,
Based on the number x of input pages and the total amount of accumulated data y up to the present time sent from the accumulated amount measuring means 17, the threshold comparing means 13 determines whether the current accumulated data amount is the area A or the area B.
Is determined. Figures (A) to (C)
As in the case of (1), this determination is made for each page of the input document.

If the result of the determination indicates that the current stored data amount is in “area A”, the gradation conversion control means 14 outputs a switching signal designating the input terminal d to the selector 12. Further, the gradation conversion control means 14 includes an 8-bit to 4-bit converter 9, an 8-bit to 2-bit converter 10, and an 8-bit to 1b
All the enable signals of the it converter 11 are negated. Therefore, when the image data of the input document of the next page is supplied later, this image data is output to the compressor 4 via the input end d. As described above, when the determination result relating to the current accumulated data amount is in the “region A”, the image data of the input document of the next page is not subjected to the gradation conversion, and the image quality of the input document is maintained. 4 is output.

On the other hand, when the result of the determination is “region B”, the gradation conversion control means 14 outputs a switching signal to the selector 12 so that the input terminal a is selected. Further, the gradation conversion control means 14 asserts only the enable signal of the 8-bit to 4-bit converter 9, and negates the enable signal of the 8-bit to 2-bit converter 10 and the 8-bit to 1-bit converter 11. Therefore, when the image data of the input document of the next page is supplied later, this image data is
The data amount is reduced via the it → 4 bit converter 9,
Thereafter, it is supplied to the compressor 4 via the input terminal a. As described above, the determination result regarding the current accumulated data amount is “area B”
, The image data of the input document of the next page is 4
The image data is converted into [bit / pixel] image data and output to the compressor 4.

By controlling as described above, similarly to the cases shown in FIGS. 9A to 9C, the input original of the next page is processed according to the total accumulated data amount y of the compressed code data up to the present time. The degree of tone conversion is determined, and the image data is compressed to reduce the data amount. Since in the case of the threshold function L ₆ in the Graph 1 (D), causing the has set amount of data per page is compared with a threshold value L ₁ in FIG (A) and (B) twice, if the drawing Even if the same originals as in (A) and (B) are input in the same order in the same number, the number of pages to be subjected to gradation conversion is smaller than in (A) and (B) of FIG. There is an advantage that the image quality of the document can be maintained as compared with FIGS.

The unit storage amount setting means 16 is configured so that a threshold value can be output based on any of FIGS. 4A to 4D, and the unit storage amount setting unit 16 determines which threshold value is to be output. The UI 15 may be configured so that it can be specified to the setting unit 16. This makes it possible to select an optimal threshold function according to the contents of the document and the number of pages.

(Modification) In the first embodiment and each of the modifications described above, the first page of the input document is already
Since the amount of stored data per page has been defined, for example, if the first page of the input document has already exceeded the amount of stored data per page, even if the storage capacity still has a margin, two pages There is a possibility that the gradation of the eyes will be converted and the image quality will be degraded more than necessary.
Therefore, for example, only in the first few pages, control may be performed so that gradation conversion is not performed even if the stored data amount exceeds the stored data amount per page. In this case, for example, when the input document page number x is 0 ≦ x ≦ 5, any function is invalidated, and the unit storage amount setting unit 16 specifies that each function is valid only when 6 ≦ x. When the number of input documents is 5 or less, control that does not perform gradation conversion regardless of the amount of accumulated data can be easily realized.

(Modification) In the first embodiment, the gradation converter is used as the data reduction means. However, the data reduction means is not limited to this, and for example, 400 dots per inch is used. Read the image 1
It is also possible to use a resolution converter or the like that performs a thinning-out process or a reduction process such as forming an image read at a sample of 200 dots per inch. Further, in addition to switching the gradation converter to reduce the data amount, the data amount may be reduced by directly changing the compression ratio by changing the compression parameter of the compressor.

(Modification) Step S21 of the second embodiment
In No. 7, document image data was re-input via the ADF 100 for all pages of the document. However, the pages already stored in the storage unit 108 may be re-input by reading the image data from the storage unit 108. As a result, the time for rereading the document can be saved, and the processing can be performed at higher speed.

(Modification) In the second embodiment, the gradation characteristic or the resolution of each page is changed in order to reduce the amount of data upon re-input (step S216).
However, the parameters to be changed are not limited to those described above, and may be other parameters. For example, the compression parameter may be changed in addition to the gradation characteristics and the resolution, the compression method may be changed depending on the type of the document, or the quantization parameter may be changed.

(Modification) In the first and second embodiments, the image data of one page of the document is used as the predetermined amount of image data. However, the unit of the image data is limited to one page of the document. Instead, other various things may be used.

[0077]

As described above, according to the configuration of the first aspect, even if the reduction rate of any one of the image data does not reach the target reduction rate, the reduction rate obtained by integrating all the image data is reduced. , A value close to the average value of each target reduction rate. According to the configuration of claim 2, even when the reduction amount of any image data does not reach the target reduction amount, the reduction amount obtained by integrating all the image data is set to the total value of each target reduction amount. It can be an approximate value.
According to the configuration of the third aspect, when an overflow occurs in the storage unit, the second reduction rate can be determined based on the total data amount measured by the measurement unit. Therefore, in any of the configurations, the optimal reduction rate is set in accordance with the available storage capacity, so that the frequency of the repetition of the reduction processing can be extremely reduced, and the image data can be rapidly accumulated. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a copying machine according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a gradation converter 2.

FIG. 3 is a block diagram of a storage amount control device 3;

FIG. 4 is an operation explanatory diagram of the first embodiment.

FIG. 5 is a block diagram of a copying machine according to a second embodiment of the present invention.

FIG. 6 is a flowchart of a main routine of the second embodiment.

FIG. 7 is a flowchart of a main routine of the second embodiment.

FIG. 8 is a flowchart of a subroutine of a second embodiment.

FIG. 9 is an operation explanatory diagram of the second embodiment.

[Description of Signs] 2 Tone converter (input reduction means, next input reduction means) 16 Unit accumulation amount setting means (target reduction rate determination means, target
Reduction amount determination means) 17 Accumulated amount measurement means (reduction rate measurement means, reduction amount measurement
Stage) 102 tone number conversion means (input reduction means, re-input reduction means) 103 resolution conversion means (input reduction means, re-input reduction means) 104 compression means (input reduction means, re-input reduction means) 105 data amount detection means (Measurement means) 108 Storage means 113 Overall control means (Overflow detection means, Measurement means, Reduction rate determination means)

Claims (3)

(57) [Claims] 1. A target reduction rate determining means for determining a target reduction rate of a data amount of image data; an input reduction means for inputting a predetermined unit amount of the image data to reduce the data amount; A reduction rate measuring means for measuring a reduction rate of the data amount of the image data reduced by: a predetermined unit amount to be reduced next if the reduction rate measured by the reduction rate measuring means is lower than the target reduction rate And a next input reduction unit configured to input the image data and reduce the input data at a higher reduction rate than the input reduction unit. 2. A target reduction amount determining means for determining a target reduction amount of image data of a predetermined unit amount, an input reduction unit for inputting a predetermined unit amount of the image data and reducing the data amount, A reduction amount measurement unit that measures a reduction amount of the image data of the predetermined unit amount reduced by the input reduction unit; and a reduction amount measured by the reduction amount measurement unit is smaller than the target reduction amount. The image processing apparatus further comprises: a next input reduction unit that inputs a predetermined unit amount of the image data to be reduced next and reduces the input data by a reduction amount larger than the input reduction unit. 3. An input reduction means for inputting image data and reducing the data amount at a first reduction rate, a storage means for storing the image data after reducing the data amount, and detecting an overflow of the storage means. Overflow detecting means, measuring means for continuously reducing the data amount by the input reducing means even after detecting the overflow by the overflow detecting means, and measuring the total data amount to be accumulated in the accumulating means, Reduction rate determining means for determining a second reduction rate based on the measured data amount and the capacity of the storage means; and re-input for re-inputting image data and reducing the data amount at the second reduction rate An image processing apparatus comprising: a reduction unit.