JP2003008903A - Image processor, its method, computer program and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate coded data contained in a size set effectively by once image input. SOLUTION: A coding section 102 applies compression processing to an image received from an input section 101 and 1st and 2nd memories 104, 106 store the compressed image. A 1st counter 107 counts its coded data quantity, when the produce coded data quantity reaches a prescribed size, a coding sequence control section 108 sets a greater quantization step to the coding section 102 and a re-coding section 109 to have a higher compression rate, cleats the 1st memory 104, allows the re-coding section 109 to re-code the coded data stored in the 2nd memory and allows the 1st memory 104 to store the result. Since the coding section 102 continues the coding according to the set quantization step, the 1st memory 104 stores the code data from the top of the image. Succeedingly, every time the data quantity stored in the 1st memory reaches a prescribed amount, the quantization step is enlarged and the processing above is repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus having a function of compressing and coding image data within a fixed code amount.

[0002]

2. Description of the Related Art Conventionally, as a still image compression method, a JPEG method using discrete cosine transform and a method using Wavelet transform have been widely used. Since this type of encoding method is a variable length encoding method, the code amount changes for each image to be encoded.

In the JPEG method, which is an international standardization method,
Only one set of quantization matrices can be defined for an image. Therefore, the code amount cannot be adjusted without pre-scanning, and there is a risk of memory over when used in a system that stores in a limited memory.

In order to prevent this, when the code amount exceeds the planned code amount, the compression ratio is changed to read the original again, or the code amount is estimated in advance by prescan to adjust the code amount. In order to do so, methods such as resetting the quantization parameter have been adopted.

As a code amount control system for performing prescan, for example, there is a system in which precompressed data is put into an internal buffer memory, decompressed, the compression parameter is changed, main compression is performed, and the data is output to an external storage. . At this time, in the main compression, the compression rate is higher than in the pre-compression.

Further, for example, there is known a method of Huffman coding a coefficient in which a DCT coefficient is level-shifted n times in order to obtain an allowable code quantity for each pixel block and reduce the code quantity. It is determined from the allowable code amount.

[0007]

However, in the past, as a compression buffer, a compression buffer more than the target compression was required, and in order to prevent the overflow of the buffer used intermediately, there is a capacity enough to record the original image data. What is needed is inevitable.

Further, in the method of repeating the encoding process,
Since a process of decoding and recompressing all the compressed data is included, there is a problem that the speed of continuous processing does not increase.

The present invention has been made in view of the above-mentioned conventional example, and an image processing apparatus and an image processing apparatus which make it possible to generate coded data that effectively fits in a set size by one image input. A control method, a computer program, and a storage medium are provided.

[0010]

In order to solve such a problem, for example, an image processing apparatus of the present invention has the following configuration. That is, in the image processing apparatus for inputting and compressing and encoding the image data, the first compression means in which the parameter for determining the compression rate is changeable, and the parameter for determining the compression rate are changeable, A second compression unit that decodes the code data compressed by the first compression unit and recompresses the code data, and monitors the amount of code data while the image data being input is being compressed by the first compression unit. At the same time, a monitoring unit that determines whether or not the code data amount has reached a predetermined amount, and if the monitoring unit determines that the predetermined amount has been reached, the compression ratio is set to the first and second compression units. Setting means for setting a parameter to be increased, and when the parameter is changed by the setting means, the second compression means re-encodes the code data previously generated by the first compression means, and the re-encoding is performed. The code data after reduction, the first
And a control means for storing the encoded data generated by the first compression means after the parameter change as the subsequent code data.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an image processing apparatus 1 according to the embodiment.
It is a functional block configuration diagram of 00. Hereinafter, each part of the figure will be briefly described.

The image processing apparatus 100 according to the embodiment is
An input unit 101 for inputting an image from an image scanner is provided. The input unit 101 may input image data from page description language rendering or the like, or may be realized by reading an image file stored in a storage medium. In some cases, it may be received from a network. You can

The encoding unit 102 encodes the input image data. In the present embodiment, a known JPEG encoding method is used as an encoding method, image data corresponding to a unit of 8 × 8 pixels is orthogonally transformed, and quantization and Huffman encoding processing using a quantization step described later are performed. Is to do.

The first memory control unit 103 and the second memory control unit 105 receive the encoded data (same encoded data) output from the encoding unit 102, respectively.
The memory 104 and the second memory 106 are controlled to be stored. Here, the first memory 104 stores the finally determined encoded data (compressed to a data amount within a target value) in a network device and an image output device connected to the outside of the basic configuration of FIG. 1. Or a memory for holding the encoded data for output to a mass storage device or the like. The second memory 106 is a working memory that assists the compression coding process for forming the coded data on the first memory.

The counter 107 counts the data amount of the image data compressed and coded by the coding unit 102, holds the count value, and controls the coding sequence based on the count result. To 108.

The encoding sequence control unit 108 detects whether the count value of the counter 107 has reached a certain set value, and when it is detected that the set value has been reached (exceeds the target value), the memory 104 is stored. A control signal is output to the first memory control unit 103 to discard the stored data of 1. The first memory control unit 103 clears the memory address counter based on this control signal, or
Alternatively, the stored data is discarded by clearing the encoded data management table. In addition, at this time, the coding sequence control unit 108 determines that the first counter 107
Is cleared to zero (input from the input unit 101 is continued), and the encoding unit 102 is controlled to perform encoding at a higher compression rate than before. That is, the data amount of the coded data generated in the coding process of the present apparatus is controlled so as to finally become, for example, 1/2. It should be noted that although it is set to 1/2 here, it can be set arbitrarily.

The coded data after the compression rate change is also
As before, it is stored in the first memory 104 and the second memory 106 via the first memory control unit 103 and the second memory control unit 105, respectively.

Further, the coding sequence control unit 108
Reads the encoded data stored in the second memory 106 so far to the second memory control unit 105,
A control signal is output to the re-encoding unit 109 which is the encoded data conversion means so as to output the encoded data.

The re-encoding unit 109 decodes the input encoded data, performs re-quantization for reducing the data amount, and then performs the encoding process again, and the encoding unit in which the compression rate is changed. The data amount having the same compression ratio as 102 is output to the second counter 110.

The encoded data output from the re-encoding unit 109 passes through the first memory control unit 103 and the second memory control unit 105, and the first memory 10 respectively.
4 and the second memory 106.

Whether or not the re-encoding process has been completed is determined by the second
Is detected by the memory control unit. That is, when there is no more data to read for the re-encoding process, the encoding sequence control unit 108 is notified of the end of the re-encoding process. Actually, the encoding process is completed after not only the reading process of the second memory control unit 105 but also the process of the re-encoding unit 109.

The count value obtained by the second counter 110 is obtained by the first counter 10 after the re-encoding process is completed.
It is added to the counter value held in 7. This addition result represents the total amount of data in the first memory 104 immediately after the re-encoding process is completed. That is, at the time when the encoding process of the encoding unit 102 and the re-encoding unit 109 for one screen is completed, the counter value held by the first counter 107 after the addition is for one screen. Represents the total amount of data generated in the case of encoding (details will be described later).

The encoding unit 102 terminates the re-encoding process /
Regardless of whether it is not finished, the encoding process is continued as long as the image data from the input unit 101 to be encoded remains.

Whether or not the count value of the counter 107 has reached a certain set value is repeated until the encoding process (encoding and re-encoding) of the image data for one page input from the input unit 101 is completed. The encoding and re-encoding processing is performed under the control according to the detection result obtained here.

A flow chart showing the flow of processing in the configuration of FIG. 1 is shown in FIG. 8. First, for simplification of description, description will first be made according to the simplified flow chart of FIG.

As described above, the image processing apparatus 100 of the present invention uses the input unit 101 such as a scanner to input 1
This is a device that compresses and encodes page image data to a predetermined data amount or less. In order to realize the encoding process, in addition to the input unit 101, an encoding unit 102 and a re-encoding unit 10
9, a first memory 104, a second memory 106, and the like. Encoding processing is performed using these functional blocks based on the flowchart shown in FIG.

The flowchart of FIG. 3 is roughly divided into the following three processing phases. (1) Encoding phase (2) Encoding / re-encoding phase (3) Transfer phase In each of the above processing phases, how image data, encoded data, etc. are processed by flow, FIG. 4 shows visually whether it is stored or not.
Through FIG. 7.

FIG. 4 shows the initial state of the encoding phase corresponding to steps S303 and S305 in the flowchart of FIG. Further, FIG. 5 shows steps S307 to S307.
6 shows the processing state of the encoding / re-encoding phase corresponding to 315, FIG. 6 shows the processing state of the transfer phase corresponding to step S317, and FIG. 7 shows the processing state of the encoding phase after the transfer phase. Each phase will be described below.

<< Encoding Phase >> The encoding process of image data for one page starts from the initial setting of encoding parameters (step S301). Here, the upper limit of the encoded data amount that is uniquely determined from the image size to be encoded (the paper size read from the input unit 101 such as a scanner) and the encoding unit 102 (known JPEG in this embodiment).
A parameter such as a quantization step (Q1) applied to the encoding system is set).

Then, in step S303, the first counter 107 performs actual encoding processing (JPEG compression in units of 8 × 8 pixels of the image) and cumulatively counts the data amount of encoded data to be output. .

Next, in step S305, it is detected whether or not the count value of the data amount exceeds the upper limit value, and if not, the JPE of step S303.
The G encoding process is continued. This is the initial encoding phase.

The encoded data output from the encoding unit 102 is stored in both the first memory 104 and the second memory 106 as shown in FIG. The area indicated by vertical stripes represents the stored code.

<< Encoding / Re-Encoding Phase >> When the encoding process of the encoding unit 102 progresses and the count value of the data amount exceeds the set upper limit value, the first step is performed in step S307. The encoded data in the memory 104 of the above is discarded, and at the same time, in step S309, the encoding unit 1
Change the quantization step of 02 to Q2.

The fact that the count value of the data amount of the encoded data exceeds the set upper limit value means that the data amount after compression does not fall within the target value. Therefore, it is meaningless to continue the encoding process using the same quantization step, so that the quantization step Q2 having a larger quantization step width than Q1 is changed so that the data amount becomes smaller than before. is there.

After changing the quantization step, step S
In 311 the encoding process of the encoding unit 102 is restarted, and as shown in FIG.
The encoded data is stored only in the second memory 106 as shown in FIG. In parallel with this, the re-encoding process of step S313 is performed. In the re-encoding process, the second memory 10
6, the encoded data stored in 6 is read out, and the re-encoding unit 109 performs re-encoding processing.
04 and 106 are stored. Then, the encoding process and the re-encoding process are continued until all the codes of the vertical stripes are re-encoded. The re-encoded data output from the re-encoding unit 109 has exactly the same code as the encoded data obtained by encoding in the same quantization step as the encoded data output from the encoding unit 102 after changing the quantization step. Data.

Specifically, in this re-encoding process, for each quantized value after the Huffman decoding of the encoded data is performed,
This is realized by performing Huffman coding again after performing a bit shift process that produces a result similar to the result of dividing these values by 2 ⁿ . This method enables high-speed re-encoding processing in that the quantization step is changed only by bit shifting and that inverse orthogonal transformation or re-orthogonal transformation processing is not performed. In step 315, the end of the re-encoding process is detected.

Since the amount of data after re-encoding is smaller than the amount of encoded data before re-encoding, as shown in FIG. 5, data is re-encoded in the memory area where the code before re-encoding is stored. The encoded data after encoding can be stored so as to be overwritten. When the re-encoding process is completed, the data amount of the coded data of vertical stripes is reduced to the data amount of the coded data of diagonal stripes shown in FIG.

Steps S307 to 315 described above
Is a process performed in the encoding / re-encoding phase.

<< Transfer Phase >> When the re-encoding process is completed, the transfer process is performed in step S317.
In the transfer processing, as shown in FIG. 6, the diagonal stripe coded data stored in only the second memory 106 in the coding / recoding phase is converted into the diagonal line coded data in the first memory 104. Transfer to the address linked to and store. On the other hand, the diagonal stripes are coded so that the coded data of the diagonal stripes and the coded data of the diagonal stripes, which are dispersed in the second memory 106, are continuously stored in the first memory 104. The encoded data of the second memory 106
Transfer within and connect. This is the process performed in the transfer phase.

When the transfer phase is completed, the process returns to the encoding phase of steps S303 and S305, and the code of the diagonal stripe is output from the encoding unit 102 and stored in the two memories 104 and 106 as shown in FIG. This coding phase is slightly different from the coding phase in the initial state (FIG. 4), and the quantization step at the time of coding by the coding unit 102 is changed from Q1 to Q2, and the two memories 104 and 106 are also used. The encoded data stored in is also a collection of codes processed in various phases. If these differences are ignored, the coding phase immediately after the transfer phase and the coding phase in the initial state can be regarded as the same.

Therefore, by repeating the three phases of the encoding phase, the encoding / re-encoding phase and the transfer phase, the code obtained by finally compressing the image data of one page to the data amount set value or less is stored in the first memory. Can be stored in. Moreover, the input unit 101 only continues the input until the series of processing is completed. That is, it is not necessary to input the image again from the beginning.

The flow chart shown in FIG. 3 describes only the processing corresponding to each phase shown in FIGS. 4, 5 and 6 for easy understanding of the explanation. However, in reality, the input of the image data of one page ends in some phase. Therefore, depending on which phase the process is completed, the subsequent actions are slightly different. FIG. 8 is a flowchart showing the flow in consideration of this. The flow chart of FIG. 8 considers the relationship between the completion of inputting one page of image data and the various processes described in FIG. 3, and here, in the flow chart of FIG.
1, S803, S805, and S807 are added.

Steps S801, S803, S805
Detects that the input of the image data for one page from the input unit 101 is completed in the encoding phase, the encoding / re-encoding phase, and the transfer phase, respectively.

When it is detected that one page of image data has been input in the encoding phase and the transfer phase (steps S801 and S805), the process moves to step S807 to end the compression encoding process of the page, and then If there is one or more pages of image data to be processed, the compression encoding process of the next one page of image data is started, and if there is none, the process enters the stopped state.

On the other hand, when the input end of the image data for one page is detected in the encoding / re-encoding phase (step S803), the encoding unit 102 operates once until there is no image data to be re-encoded. Therefore, the re-encoding process for passing the encoding process of step S311 and suppressing the image data already encoded by the encoding unit 102 to a predetermined encoded data amount in step S313. Only continue. If all the re-encoding processing is completed and the subsequent transfer processing is not completed, the encoded data of the entire image data for one page cannot be collected in the first memory, and the input of the image data for one page is completed. After that, the re-encoding process and the subsequent transfer process need to be continuously performed. In this case, when it is detected in step S315 that all the re-encoding processing has been completed, encoding /
During the re-encoding phase, the encoded data stored only in the second memory 106 is transferred to the first memory (step S317), and then in the next step S805, the image data for one page is input. When the end is detected, step S80
I will move to 7.

The above is the operation in the embodiment, and FIG.
Is also the operation description.

<Modification of Memory Storage Method> FIGS. 9 and 10
FIG. 9 is a diagram showing a modification of the memory storage method shown in the conceptual diagrams of FIGS. 5 and 6.

In the conceptual diagram of FIG. 5, in the encoding / re-encoding phase, the encoded data output from the encoding unit 102 is stored only in the second memory 106.
As shown in, during the encoding / re-encoding phase, the encoded data output from the encoding unit 102 is directly stored in both the first and second memories.

From the viewpoint of the encoding unit 102, the encoded data which is encoded and output in any phase is stored in both memories. Also, unlike the conceptual diagram of FIG. 6, as shown in FIG. 10, data transfer between memories is not necessary in the transfer phase. In the case of this modification,
In the re-encoding phase, the encoded data and the re-encoded data are sequentially stored in the order sent to the first memory 104. Therefore, there is a problem that two types of data are mixed.

Therefore, in the case of this modification, in order to cope with this, the encoded data is divided into certain units and managed as files or packets. In particular,
A file management table or a packet management table is separately created and managed.

As one method, when the data from the encoding unit 102 is stored in the first memory 104, an appropriate unit (for example, since the unit of the orthogonal transformation is a block of 8 × 8, 8 × i ( A management number is allocated from the beginning of the image data for each i), i.
A management table is created so that the storage start address of the encoded data corresponding to each management number and the encoded data amount can be stored in the order of the management numbers.

The encoding unit 102 and the re-encoding unit 109 hold the management number of the data being processed, and based on the management number, the start address and the encoded data amount at the time of storing the encoded data are stored in the management table. Write. By doing so, even if the encoded data processed by the encoding unit 102 and the re-encoding unit 109 is stored at random, the management table is accessed in the order of the management numbers, and the start address and the encoded data to be read at that time are read. The first encoded data based on the quantity
If the data is read from the memory 104, the encoded data can be read in order from the beginning of the image. If such a management mechanism is provided, there is no need to store continuous data on the image in the memory so as to be continuous.

The encoding phase after the transfer phase in the conceptual diagram of FIG. 10 is almost the same as the two encoding phases described above (FIGS. 4 and 7), and the storage state of the code in the first memory. Are only slightly different as shown in FIG. Therefore, the above description and this modification are 3
There is no change in processing one phase repeatedly.

<Second Embodiment> A second basic configuration for performing the encoding process characteristic of the present invention will be described below with reference to FIG.

FIG. 2 is a block diagram of the image processing apparatus 200 according to the second embodiment.

A major difference from the image processing apparatus 100 shown in FIG. 1 is that there are two encoding units that perform encoding first in parallel. In the image processing apparatus 200, the image data input from the input unit 201 is coded in parallel by the first coding unit 202 and the second coding unit 205, and two types of coded data having different compression rates are obtained. To generate. Also in the present embodiment, a known JPEG encoding method is used as an encoding method, image data corresponding to a unit of 8 × 8 pixels is orthogonally transformed, and quantization and Huffman encoding processing using a quantization step described later are performed. It is something to do.

In the second embodiment, the case where the compression rate applied by the second coding unit 205 is set higher than that of the first coding unit 202 will be described. Specifically, the quantization step in the first encoding unit 202 is Q
1, the quantization step of the second encoding unit 205 is Q2 (=
2 x Q1).

The encoded data output from the encoding unit 202 is stored in the first memory 204 via the first memory control unit 203. At this time, the first counter 2
08 counts the data amount of the encoded data output from the encoding unit 202, holds it, and outputs it to the encoding sequence control unit 209.

On the other hand, the encoded data encoded by the encoding unit 205 is stored in the second memory 207 via the second memory control unit 206. At this time, the second counter 210 counts the data amount of the encoded data output from the encoding unit 205 and holds it. Furthermore,
When the coded data stored in the second memory 207, which will be described later, is transferred to the first memory 204, at the same time, the count value is transferred to the first counter 208.

Now, the first counter 208 is the encoding unit 2
While counting the data amount of the encoded data output from 02, when the count value reaches a certain set value, the encoding sequence control unit 209 determines the same as in the first embodiment.
A control signal is issued to the memory control unit 203 to discard the data stored in the memory 204.

Then, the encoding sequence control unit 209
Sends a control signal to the memory control unit 206 and the memory control unit 203 so that the encoded data stored in the second memory 207 is read out, transferred to the first memory 204, and stored in the first memory 204. Output. As a result, the count value of the second counter 210 is transferred to the first counter 208, and the value is loaded (overwritten) as the count value of the first counter.

In short, since the count value of the second counter 210 represents the data amount of the encoded data stored in the second memory 207, the count value and the encoded data correspond to each other. So that the attachment does not change,
It may be considered that the data is copied to the first counter and the first memory as it is.

Further, the coding sequence control 209 is
A control signal is issued to the first encoding unit 202 and the second encoding unit 205 so that encoding is performed so that the encoded data becomes smaller than ever.

For example, the quantization step S in the first coding section 202 and the second coding section 205 is switched to double. As a result, the first coding unit 202 inherits the quantization step Q2 (= 2 × Q1) in the second coding unit 205 up to immediately before, and the second coding unit 205 further A large quantization step Q2 × 2 is used to perform a coding process with a higher compression rate in preparation for the next overflow.

Here, the magnification ratio of the quantization step is set to 2 times, but it is not limited to this, and it goes without saying that it can be set arbitrarily. The encoded data output from each of the switched encoding units 202 and 205 is passed through the corresponding memory control units 203 and 206, respectively, and the corresponding memory 2
04 and 207 are stored.

Then, the coding sequence control 209
The encoded data already stored in the second memory is read out to the memory control unit 206, and the re-encoding unit 211 is read.
Send a control signal to send data to. Re-encoding unit 211
Performs re-encoding processing of encoded data in the same manner as re-encoding section 109 in FIG.

The third counter 212 has a re-encoding unit 21.
1 counts the amount of data output, is reset to zero immediately before starting the re-encoding process, and counts the amount of output data during the re-encoding process. This counter 21
2 transfers the count value obtained there to the second counter 210 when the re-encoding process is completed.

The second counter 210 stores the transferred data amount count value in the memory 207 during the re-encoding process by adding the transferred data amount count value to the counter value held in the second counter 210. Then, the total data amount of the encoded data and the re-encoded data is calculated. That is, the amount of data stored in the memory 207 and the count value of the counter 210 match.

Regardless of whether the re-encoding process is completed or not,
If the image data from the input unit 201 to be encoded remains, the encoding process by the two encoding units 202 and 205 is continuously performed. The input unit 20 monitors whether or not the count value of the counter 208 has reached a certain set value.
It is repeated until the encoding process (encoding, re-encoding) of the image data for one page input from 1 is completed, and the above-mentioned encoding and re-encoding processes are performed according to the detection result obtained here. Performed under control.

FIG. 12 is a flowchart showing the flow of processing in the configuration of FIG.

When there are two encoding units as described with reference to FIG. 2, the image data for one page is encoded based on the flowchart shown in FIG. Note that the description of FIG. 12 is mostly similar to FIG. 8 which is the flowchart in the case where there is one encoding unit, and those skilled in the art can fully understand the features of the second embodiment from the above description. Since it can be understood, the processing will be described in three phases as in the case of one encoding unit, and the points different from FIG. 8 will be mainly described.

The biggest difference between the above-described flow of FIG. 8 and the flow of the present embodiment is that the transfer processing of step S317 is moved between step S307 and step S309. In short, it may be considered that the encoding / re-encoding phase and the transfer phase are exchanged (the exception is the processing of discarding encoded data in step S307).

In the initial setting of the coding parameter in step S301, the quantization step Q is set in the first coding section 202.
1 to the second encoding unit 205 at the quantization step Q2.
(= 2 × Q1) is set.

In the encoding phase, steps S801,
S303 and S305 are repeatedly executed. Step S8
01 and step S305 are the same processes as in the case where there is one encoding unit, but only the encoding process of step S303 is different as shown in FIG.

In order to increase the compression rate of the encoded data stored in the first memory 204 step by step, the encoded data stored first is encoded in the quantization step Q1 having the lowest compression rate. The encoded data that stores the data and that is stored in the second memory is the data that is encoded in the quantization step Q2.

When the amount of data being stored in the first memory 204 exceeds the set upper limit value (step S3)
05), immediately, the encoded data held in the first memory 204 is discarded (step S307), and the encoded data having a high compression rate held in the second memory 207 is
The data is transferred to the first memory 204 (step S317, see FIG. 14). As a result, the appropriate second candidate coded data that does not exceed the upper limit can be promptly obtained without waiting for the end of the first re-encoding process described in the first embodiment (FIG. 1). Can be stored in the memory 207. This is the greatest advantage of applying FIG. 2 with two encoders to FIG.

In the second embodiment, two memories 20 are provided.
Since it is wasteful that the coded data of 4 and 207 have the same compression rate, the second memory 207 has coded data with a higher compression rate than the coded data stored in the first memory 204. Is stored. Therefore, the subsequent processing is also performed based on this idea, and the processing of transferring the encoded data in the second memory 207 to the first memory 204 (transfer phase)
After the above, the encoded data in the second memory 207 is re-encoded so as to retain the encoded data having a higher one-step compression rate.

Specifically, first, as shown in FIG. 15, in the encoding / re-encoding phase subsequent to the transfer phase, it is applied to the two encoding units 202 and 205 before the re-encoding. Quantize steps Q1 and Q2 to Q2 and Q3, respectively.
(Step S309), if the input of the image data of one page continues without being completed (step S80)
3) For the subsequent image data, the input data is encoded by the two encoding units in which new quantization steps are set (step S311) and stored in the corresponding memories 204 and 207. Then, in parallel with the above-described encoding process, the encoded data stored in the second memory (the first memory 20
4) is encoded by the re-encoding unit 211 using the quantization step Q3 so as to be changed to encoded data having a compression ratio one step higher than the encoded data in the first memory. Re-encoding process (S3
13) is performed and the re-encoded data is stored in the second memory 207.
Store again.

In the second embodiment, as in the first embodiment, in the re-encoding process, these values are set to 2 for each quantized value after Huffman decoding the encoded data once.
It is realized by performing Huffman coding again after performing a bit shift process that produces a result similar to the result divided by ⁿ . This method enables high-speed re-encoding processing in that the quantization step is changed only by bit shifting and that inverse orthogonal transformation or re-orthogonal transformation processing is not performed.

When there are two encoders as in the second embodiment, the encoded data and the re-encoded data are mixed in the second memory 207 as shown in FIG. There is a situation where it is stored. Therefore, as described above, it is also necessary for the second memory 207 to divide the encoded data into certain units and manage them as files or packets. For that purpose, for example, a configuration similar to that of the modification of the first embodiment may be provided.

In FIG. 12, when the end of the re-encoding process is detected in step S315, the process proceeds to the encoding phase (steps S801 and S303). In the encoding phase after the encoding / re-encoding phase, as shown in FIG. 16, not only the encoded data held in the two memories 204 and 207 have different compression rates but also mixed encoded data. The method (address) is also quite different. Therefore,
Again, when the data amount of the first memory 204 exceeds the set value, the encoded data (the code of the + horizontal stripe area) held in the second memory 207 is transferred to the first memory 204. Will need to be done. Considering these points, it is necessary to manage the encoded data as a file or packet not only in the second memory 207 but also in the first memory 204. Therefore, the first memory 204 also needs a management mechanism using the above-mentioned management table.

The state of the encoding phase shown in FIG. 16 is different from the encoding phase (in the initial state) except that the method of mixing the quantization step and the encoded data is different before and after the re-encoding process. (Fig. 13). Therefore, by repeating the encoding phase, the transfer phase, and the encoding / re-encoding phase, it is possible to ensure that the encoded data obtained by compressing the image data of one page to the set upper limit value or less is finally stored in the first memory. It can be stored in 204.

Since the arrangement order of the transfer phase and the encoding / re-encoding phase is opposite to that of the first embodiment, the image data for one page, which was performed after the transfer processing in FIG. 8, is performed. Input end detection (step S80
5) is the detection of the end of inputting one page of image data performed in the encoding / re-encoding phase (step S803),
The timing is almost the same. Further, the two detection processes are functionally the same as step S805 and are the same in timing as step S803. Therefore, these two steps detect the end of input of a new page of image data. Are integrated as steps to be performed, and are referred to as step S1201.

In the first and second embodiments described above,
The first memory and the second memory have been described as being physically different memories. This is advantageous because the access to the two memories can be independent, and is a feature of the present invention. However, the case where the first memory and the second memory are not physically separate memories is also included in the scope of the present invention. Two areas corresponding to the first memory and the second memory are physically secured on one memory, and the first memory is the first memory area and the second memory is the second memory. It can be understood that the present invention can be realized by a single memory, by re-reading the description given so far as a region.

When the above embodiments are implemented by one memory, some of the data transfer processing described in the transfer phase becomes unnecessary. The details are omitted because they can be easily imagined each time. However, when the two areas are strictly separated from each other, the data transfer processing is required as in the case of physically having two memories. Two
If the same data is shared between the two areas, not only the data transfer processing becomes unnecessary, but also the storage capacity can be reduced.

For example, when the encoded data held in the second memory area is transferred to the first memory area, two pieces of information, that is, the head address where the encoded data is stored and the data size, are stored in the second information. Only by transferring from the second memory control unit to the first memory control unit, the same effect as the transfer of the encoded data can be obtained.

When the encoded data is stored in the file format or the packet format, the information transferred between the memory control units is slightly increased, and it is necessary to transfer the management table information related to the encoded data. is there. Nevertheless, it is more efficient than transferring the encoded data.

<Application Example> In the first and second embodiments described above, the functional operation of the apparatus has been described by taking the apparatus for reading an image from the image scanner as an example. Most of the functions (including the encoding process) can be realized by the computer program as described above.

Therefore, the present invention may be applied to an application program operating on a general-purpose information processing device such as a personal computer. When applied to an application program, a GUI for allowing the user to specify an image file as a compression source and allowing the user to select a target size may be provided. The target value at this time can be arbitrarily set by the user, but it is difficult to understand the numerical setting, so select from an intuitive and easy-to-understand menu that considers the document size and image quality (high, medium, low, etc.). Then, it will be better to make a decision.

In the first and second embodiments, the quantization step has been described as an example of the coding parameter of the coding section. However, when data having different compression ratios are mixed, the quantization step is performed between them. Other parameters may be used as long as the image quality does not cause discomfort. However, for example, in the configuration of FIG. 1, in order to make the data to be re-encoded from the re-encoding unit 109 substantially the same as the encoded data from the encoding unit 102 after the parameter change, As shown in the form, a method of increasing the quantization step is preferable.

Further, as described above, the present invention can be realized by an application program that operates on a general-purpose device, so the present invention also includes a computer program. The computer program is usually a floppy (registered trademark) disk or CDRO.
This is performed by setting a storage medium such as M in the apparatus and copying or installing the storage medium, and thus such a storage medium is naturally included in the scope of the present invention.

The present invention can also be applied to a combination of a computer program and appropriate hardware (encoding circuit etc.).

As described above, according to this embodiment,
After the image data is frequency-converted, it is quantized to perform variable-length coding, a quantization step control means for switching and controlling the quantization step used in the quantization, and the encoding means. Encoding the resulting encoded data to another encoded data to be obtained by encoding in a quantization step different from the quantization step used to obtain the encoded data Coded data conversion means installed separately from the means, storage means for storing the coded data obtained by the coding means or the coded data conversion means for at least one page, and stored in the storage means. Monitoring means for monitoring the amount of encoded data, and changing the quantization step in the quantization step control means according to the amount of encoded data, By controlling both of the encoded data converting means in cooperation with each other, it is possible to ensure that the image data for one page has a desired encoded data amount by one encoding process in a memory with a small capacity. Can store encoded data.

[0095]

As described above, according to the present invention, 1
By inputting images once, it becomes possible to effectively generate encoded data that fits in the set size.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an image processing apparatus according to a first embodiment.

FIG. 2 is a block configuration diagram of an image processing apparatus according to a second embodiment.

FIG. 3 is a flowchart showing a simplified process in the first embodiment.

FIG. 4 is a diagram showing a data flow and a memory content in a coding phase in an initial state according to the first embodiment.

FIG. 5 is a diagram showing a data flow and a memory content in an encoding / re-encoding phase according to the first embodiment.

FIG. 6 is a diagram showing a data flow and a memory content in a transfer phase in the first embodiment.

FIG. 7 is a diagram showing a data flow and a memory content in an encoding phase after a transfer phase in the first embodiment.

FIG. 8 is a flowchart showing details of processing in the first embodiment.

FIG. 9 is a diagram showing a data flow and a memory content in an encoding / re-encoding phase in the modification of the first embodiment.

FIG. 10 is a diagram showing a data flow and a memory content in a transfer phase according to a modification of the first embodiment.

FIG. 11 is a diagram showing a data flow and a memory content in an encoding phase after a transfer phase in the modification of the first embodiment.

FIG. 12 is a flowchart showing a processing procedure according to the second embodiment.

FIG. 13 is a diagram illustrating a data flow and a memory content in a coding phase in an initial state according to the second embodiment.

FIG. 14 is a diagram showing a data flow and a memory content in a transfer phase in the second embodiment.

FIG. 15 is a diagram showing a data flow and a memory content in an encoding / re-encoding phase according to the second embodiment.

FIG. 16 is a diagram showing a data flow and a memory content in an encoding phase after an encoding / re-encoding phase in the second embodiment.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoki Ito             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Tadayoshi Nakayama             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Hidefumi Osawa             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 5C059 KK08 KK11 KK35 MA00 MA23                       MC11 MC38 ME02 PP01 SS20                       TA46 TB04 TC18 TD12 UA02                       UA35 UA36 UA37                 5C078 BA57 DB07

Claims (10)

[Claims] 1. An image processing apparatus for inputting and compressing and encoding image data, comprising: a first compression unit in which a parameter for determining a compression rate is changeable; and a parameter for determining a compression rate is changeable. Second compression means for decoding and recompressing the code data compressed by the first compression means, and code data in the middle of compressing the image data being input by the first compression means. Monitoring means for monitoring the amount and determining whether or not the code data amount has reached a predetermined amount, and if the monitoring means determines that the predetermined amount has been reached, the first and second compression means Setting means for setting a parameter for increasing the compression rate, and when the parameter is changed by the setting means, the second
The code data previously generated by the first compression means is re-encoded by the compression means and the code data after the re-encoding is stored as the code data after the parameter change of the first compression means. In addition, the image processing apparatus is provided with a control unit that stores the encoded data generated by the first compression unit after the parameter change as subsequent encoded data. 2. The image processing apparatus according to claim 1, wherein the parameter is a quantization step in quantization processing. 3. The code data generated by the first compression means is written in the first and second memories at the same time, and when the control means determines that the predetermined data amount has been reached by the monitoring means, The first memory is cleared, the code data stored in the second memory is re-encoded by the second compression unit, and the code data is stored in the first memory. The image processing apparatus according to claim 1. 4. A method of controlling an image processing apparatus for inputting image data and performing compression encoding, comprising: a first compression step in which a parameter for determining a compression rate is changeable; and a parameter for determining a compression rate is changed. A second compression step of decoding the coded data compressed by the first compression means and re-compressing it, and compressing the image data being input by the first compression step. Monitoring the code data amount and determining whether or not the code data amount has reached a predetermined amount; and when the monitoring process determines that the predetermined amount has been reached, the first and second A setting step of setting a parameter for increasing the compression rate in the compression step, and the second step when the parameter is changed in the setting step
Re-encode the code data previously generated by the first compression means by the first compression step, and store the re-coded code data as code data after the parameter change of the first compression step. And a control step of storing the coded data generated in the first compression step after the parameter change as subsequent coded data. 5. A computer program which functions as an image processing device for inputting and compressing and encoding image data, comprising: a program code of a first compression step in which a parameter for determining a compression rate is changeable; The program code of the second compression process, in which the parameter to be determined is changeable, the code data compressed by the first compression unit is decoded and recompressed, and the image being input by the first compression process. A program code of a monitoring process for monitoring the code data amount during data compression and determining whether the code data amount has reached a predetermined amount, and that the predetermined amount has been reached by the monitoring process. If judged, the program code of the setting step for setting the parameter for increasing the compression rate in the first and second compression steps, and the parameter by the setting step. If you change the said second
Re-encode the code data previously generated by the first compression means by the first compression step, and store the re-coded code data as code data after the parameter change of the first compression step. And a program code of a control step for storing the encoded data generated in the first compression step after parameter change as subsequent encoded data. 6. A storage medium on which the computer program according to claim 5 is stored. 7. An image processing device for inputting and compressing and encoding image data, comprising first and second compression means capable of changing a parameter for determining a compression rate, and changing parameters for determining a compression rate. A third compression unit that is capable of decoding the coded data compressed by the second compression unit and re-compresses the compression ratio of the second compression unit, and the compression ratio of the first compression unit. In order to make it higher, the setting means for setting different parameters respectively, and the code generated by the first compression means while the image data being input is being compressed by the first and second compression means. Monitoring means for monitoring the data amount and determining whether or not the code data amount has reached a predetermined amount, and if the monitoring means determines that the predetermined amount has been reached, the second compression at that point The parameter that was set as a means Parameter as the parameter of the first compressing means, and updating means for updating the parameter of the second compressing means in order to further increase the compression rate of the second compressing means, and the parameter by the updating means. If you update the second
The code data previously generated by the compression means is re-encoded by the third compression means, and the code data generated by the second compression means is re-encoded by the first compression means after parameter updating. And a control unit that stores the code data newly generated by the first compression unit as the subsequent code data. 8. A method of controlling an image processing apparatus for inputting image data and performing compression encoding, comprising first and second compression steps in which a parameter for determining a compression rate is changeable, and a compression rate is determined. A third compression step in which the parameter is changeable, the coded data compressed by the second compression means is decoded and recompressed, and the compression rate of the second compression step is set to the first compression means. In the setting step of setting different parameters for each of them in order to make it higher than the compression rate, and while the image data being input is being compressed in the first and second compression steps, it is generated in the first compression step. A monitoring step of monitoring the code data amount that has been generated and determining whether or not the code data amount has reached a predetermined amount, and if the monitoring step determines that the predetermined amount has been reached, the first step at that point Set to 2 compression process Updating the parameter as the parameter of the first compression means and updating the parameter of the second compression step in order to further increase the compression rate of the second compression step; If the parameters are updated, the second
Of the compression data previously generated in the compression step of FIG. 3 is re-encoded in the third compression step, and the code data generated in the second compression step is converted into the first compression step after parameter updating. And a control step of storing the code data newly generated in the first compression step as subsequent code data. 9. A computer program which functions as an image processing apparatus for inputting and compressing and encoding image data, wherein program parameters of first and second compression steps in which a parameter for determining a compression rate is changeable, In order to make the compression rate of the second compression step higher than the compression rate of the first compression means, the program code of the setting step for setting different parameters and the image data being input are set to During the compression in the second compression step, the program code of the monitoring step for monitoring the code data amount generated in the first compression step and determining whether or not the code data amount reaches a predetermined amount When it is determined by the monitoring step that the predetermined amount has been reached, the parameter set in the second compression step at that time is set to the parameter of the first compression means. Program code of the updating step for updating the parameter of the second compressing step in order to further increase the compression rate of the second compressing step and the parameter is updated by the updating step. Second
Of the compression data previously generated in the compression step of FIG. 3 is re-encoded in the third compression step, and the code data generated in the second compression step is converted into the first compression step after parameter updating. And a program code of a control step of storing the code data newly generated in the first compression step as the subsequent code data. 10. A storage medium storing the computer according to claim 9.