JP2001186354A - Picture processor and picture processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture processor and a picture processing method, which can compress a picture so that deterioration of picture quality does not occur after decoding and stripe synthesis even if an area which is to be compressed does not match a compression unit at the time of stripe division and compression. SOLUTION: A picture input 1 inputs the picture and a stripe division part 2 conducts stripe division. An offset processing part 3 obtains an offset position and valid picture data length on divided stripes. When valid picture data length does not match the multiple number of the number of lines in compression unit in a compression part 4, valid picture data length is re-decided. When the end position of a valid picture data area matches a stripe final line position at the time of re-decision, the offset position is set again. Thus, valid picture data length matches the multiple number of the number of lines in the compression unit so as to conduct compression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and an image processing method for dividing input image data into certain regions and encoding the divided image data.

[0002]

2. Description of the Related Art In general, when compressing an image, there are a case where all target image data is encoded at a time, and a case where target image data is divided into a plurality of regions and then encoded for each region. There is. A typical example of these is encoding at the time of facsimile transmission. There are various types of facsimile machines currently on the market. For example, there is a facsimile machine in which the entirety of a document read by a transmission side is stored in a memory, encoded by a predetermined encoding method, and transmitted. Further, as another facsimile, there is a facsimile apparatus that reads one document at several lines on the transmission side, repeats encoding and transmission, and transmits one document.

[0003] The amount of data that can be transmitted at one time during transmission and reception is not determined only by the transmitter, but also depends on the capability of the receiver. For example, devices used in offices have a large amount of memory,
It is possible to read, encode and transmit each time.
However, when a memory is not installed much like a device used in a general household, the data is transmitted by dividing the amount of data that can be encoded at a time into several times. The same applies to the reception. If the data is not received by the amount of data that can be decoded at a time, the data cannot be received normally. Therefore, for example, even if the transmitter is equipped with a large amount of memory and it is possible to read and encode all the placed documents at once, if the receiver does not have much memory, The transmission is divided into several times for each data amount that can be decoded at one time on the device side. In such a case,
On the transmitter side, a function of dividing the image data into a plurality of regions, encoding them, and transmitting them is required.

FIG. 2 is an explanatory diagram of an example of an image, and FIG. 3 is an explanatory diagram of an example of stripe division. In the figure, 11 is a background portion, 12 is a character portion, and 13 is a photograph portion. For example, as shown in FIG.
And an image in which the photograph unit 13 is drawn. When such image data is divided as shown in FIG. 3, the divided image data area is called a stripe, and the divided image data is called a stripe image. The division into stripes is referred to as stripe division. Further, a division boundary at the time of stripe division is called a stripe division boundary. The stripe length indicates the length of the stripe in the sub-scanning direction.

FIG. 3A shows an example in which the image shown in FIG. 2 is divided into stripes with a constant stripe length. In this case, some stripes include lines of the background portion 11 and image portions to be compressed such as the character portion 12 and the photograph portion 13. In FIG. 3A, the stripes 1 and 2 correspond. In such a case, it is possible to transmit an image portion to be compressed as an effective image and an offset (for example, the number of lines) and compressed data with an offset up to the head position.

FIG. 3B shows an example in which the image shown in FIG. 2 is divided into stripes according to the attributes of the image. The image is divided into a background portion 11 and a character portion 12 or a photograph portion 13. ing. In this case, the background portion 11 may transmit the number of lines or the like in the same manner as the offset, and only the stripe including the character portion 12 or the photograph portion 13 may be subjected to compression processing. When performing such stripe division,
The stripe length is undefined. However, as described above, the upper limit of the stripe length is determined by the amount of memory and the like. Therefore, in the example shown in FIG.
An example is shown in which the image is further divided by the upper limit of the stripe length.

[0007] Generally, compression is performed for each predetermined processing unit. The processing unit differs depending on the encoding system. For example, there is a unit which performs encoding in units of one line, and a unit which performs encoding in units of 8 × 8 pixels like the JPEG encoding system. In the case of using a compression method in which encoding processing is performed in units of a plurality of lines, it is necessary that the horizontal and vertical lengths of image data to be encoded are always multiples of the processing unit at the time of compression. But,
As described above, the data amount at the time of transmitting an image by facsimile is determined according to the capability between the transmitter and the receiver, and the image data of one document may be divided into stripes and transmission and reception may be repeated. In such a case, since the stripe length is determined in consideration of the capabilities of both the own apparatus and the other apparatus, the stripe division cannot always be performed so as to match the processing unit in compression.

In the encoding method described in Japanese Patent Application Laid-Open No. Hei 8-125872, for example, as shown in FIG. 3B, stripe division is performed according to the attribute of an image, and an appropriate code is applied to each stripe. The encoding is performed using an encoding scheme. However, when division is performed according to image attributes, the length of each stripe is variable, and the processing unit at the time of encoding may differ depending on the image attributes included in the stripe. Therefore, not all of the stripe regions always match the multiple of the processing unit at the time of compression.

For a part that does not match the processing unit at the time of compression, an error may occur depending on the compressor,
Alternatively, compression may be performed by automatically adding arbitrary data. In the latter case, the compression process is performed temporarily, but when a lossy compression method such as the JPEG encoding method is applied, arbitrary data is added to an arbitrary position and compression is performed. Occurs. In particular, there is a problem that the mismatch at the stripe division boundary becomes remarkable.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when performing compression by dividing into stripes, even if the area to be compressed does not match the compression processing unit, the decoding and decoding are performed. It is an object of the present invention to provide an image processing apparatus and an image processing method capable of compressing an image so that image quality does not deteriorate after stripe composition.

[0011]

According to a first aspect of the present invention, an input image is divided into stripe images, and compression processing is performed for each of the divided stripe images. At this time, if, for example, the background image and the valid image are included in the stripe image, the start point of the valid image and the subsequent image are compressed by offset processing. For example, when the image is divided into stripe images of a predetermined length, the area to be compressed after the offset processing may not be a multiple of the processing unit at the time of compression, even if it is a multiple of the processing unit at the time of compression. If the compression target area after the offset is not a multiple of the compression processing unit in the compression step, a position before the start point of the effective image is set as the offset. As a result, the compression processing can be performed for each predetermined processing unit, and it is possible to prevent occurrence of an error at the time of encoding and deterioration of image quality after decoding.

According to a second aspect of the present invention, an input image is divided into stripe images of an arbitrary length, and compression processing is performed for each of the divided stripe images. At this time, the area of the stripe image to be compressed may not be a multiple of the compression processing unit. In such a case, the compression is performed including the missing image from the stripe image adjacent to the compression target stripe image. As a result, the compression processing can be performed for each predetermined processing unit, and it is possible to prevent occurrence of an error at the time of encoding and deterioration of image quality after decoding. The stripe image adjacent to the stripe image to be compressed can be the stripe image before or next to the stripe image to be compressed.

[0013]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 1 is an image input unit, 2
Denotes a stripe division unit, 3 denotes an offset processing unit, and 4 denotes a compression unit. The image input unit 1 inputs image data. For example, it may be configured by an input device such as a scanner or a digital camera, may read image data stored in advance, receive image data sent via a network or the like, or receive an image from another software. You may receive data.

The stripe division unit 2 divides image data input from the image input unit 1 into stripes. Any method can be used as the stripe division method.
For example, the image may be divided by a fixed stripe length for each apparatus, may be divided by a fixed stripe length for each document, or may be divided to a fixed stripe length for each page.
In the example described below, it is assumed that the fixed stripe length is a multiple of the number of lines of a predetermined processing unit when the compression unit 4 performs compression.

The offset processing unit 3 determines an offset value for each stripe divided by the stripe division unit 2 and an effective image data length. First, an object existence area and an object non-existence area are detected for each stripe. Any method may be used as the method for detecting the object existence area. For example, it is assumed that all the lines having the same pixel value are determined as a background area, and a line that does not satisfy this condition has an object such as a character or a photograph.
Then, the determination is performed for each line, and a method of extracting an effective image data area including all the object existing lines from all the determination results can be used. When an object existing area is detected, the start position is set as a temporary offset, and the length of the object existing area in the sub-scanning direction is set as a temporary effective image data length. It is determined whether or not the temporary effective image data length matches a multiple of the number of lines of the processing unit in the compression unit 4 to be performed next, and if they match, the offset and the effective image data length are applied as they are. If they do not match, the offset and the effective image data length are determined again so as to match. For example, the offset can be shifted by an insufficient number of lines so that the effective image data length is a multiple of the number of lines of the processing unit in the compression unit 4.

The compression section 4 compresses an image in an area having an effective image data length from the offset position determined by the offset processing section 3 by a predetermined coding method for each predetermined processing unit.

FIG. 4 is a flowchart showing an example of the operation according to the first embodiment of the present invention. In the figure, St
n is the n-th stripe, s_y is the offset position in the stripe of interest, e_y is the end point position of the effective image data area in the stripe of interest, l_y is the length of the effective image data area in the stripe of interest in the sub-scanning direction, and h_y is The last line position of the target stripe, c, indicates a compression processing unit.

In step S21, an image is input by the image input unit 1, and in step S22, stripe division is performed by the stripe division unit 2. In S23, the variable n is initialized to 1, and the first stripe is set as the target stripe.

In S24, the offset processing unit 3
For the n-th stripe set as the target stripe, the offset position s_y, the end point position e_y of the effective image data area, the effective image data length l_y, and the stripe end line position h_y are obtained. Then, in S25, it is determined whether or not the effective image data length l_y matches a multiple of the processing unit c of the compression processing performed by the compression unit 4. This determination may be made by determining whether l_y% c = 0 (Equation 1) holds. Here, the operator '%' is an operator for calculating the remainder. If Expression 1 is satisfied, the effective image data length l_y matches a multiple of the compression processing unit c, and the compression processing can be performed as it is. And in S30,
The compression unit 4 compresses the image in the area of the effective image data length l_y from the offset position s_y of the stripe of interest Stn.

If Equation 1 is not satisfied, it indicates that if the compression processing is performed for each compression processing unit c as it is, the number of lines becomes insufficient. In this case, in S26,
The valid image data length is determined again. That is, a new effective image data length l_y ′ is obtained by α = c− (l_y% c) (Equation 2) l_y ′ = l_y + α (Equation 3)

Next, in S27, it is determined whether or not the end point position of the effective image data area matches the stripe last line position. That is, it may be determined whether or not e_y = h_y (Equation 4). If Expression 4 is satisfied, it is not possible to find a line that is insufficient in the compression processing below the effective image data area. Therefore, the offset is adjusted and it is determined again to include the upper line of the effective image data area. That is, in S28, s_y ′ = s_y−α (Equation 5) is calculated, and a new offset position s_y ′ is obtained. Then, the obtained new offset position s_y ′ and S26
It is determined that the new effective image data length l_y ′ obtained in is applied.

If Equation 4 is not satisfied in S27, S
24, the offset position s_y is applied as it is, and the new effective image data length l_
It is determined that y ′ is applied. By applying the new effective image data length l_y ′, the last line of the effective image data area may exceed the stripe last line position h_y. In such a case, Equation 5 is used, or the final line position h_
It is preferable to subtract the offset position s_y by the number β of lines protruding from y and calculate and apply a new offset position s_y ′.

After the offset position and the effective image data length to be applied are determined in this way, in S30, the area corresponding to the new effective image data length l_y 'from the offset position s_y of the target stripe Stn or the new offset position s_y' is determined. Are compressed by the compression unit 4 by a predetermined coding method for each predetermined processing unit.

In S31, it is determined whether or not processing has been completed for all stripes. That is, it is determined whether or not the value of the variable n has become equal to the total number N of the stripes. If unprocessed stripes remain, S32
In, the value of the variable n is increased by 1, the next stripe is set as the target stripe, and the process returns to S24 to repeat the same processing. When the value of the variable n becomes equal to the total number N of the stripes and the processing has been completed for all the stripes, the processing ends.

An example of the operation in the first embodiment will be described using a specific example. Here, as an example,
A case where the image shown in FIG. 2 is divided into stripes and compressed as shown in FIG. 3A will be described. FIG.
For each of the divided stripes as shown in FIG.
The processing of S24 to S30 is performed in order.

As described above, first in S24, the offset position s_y and the end point position e_ of the effective image data area are set.
y, the effective image data length l_y, and the stripe final line position h_y are obtained. FIG. 5 is an explanatory diagram of an example of an offset position and an effective image data length. For example, FIG.
The offset position, effective image data length, and stripe length in the second stripe St2 shown in FIG. In the example shown in FIG. 5, the last line position h_y of the stripe is also the end point position e_y of the effective image data area.

In S25, it is determined whether or not Expression 1 is satisfied. Here, it is assumed that Equation 1 does not hold. Then, in S26, the new effective image data length l_y '
Is calculated. Then, in S27, as shown in Expression 4, the end point position e_y of the effective image data area is compared with the stripe end line position h_y. For example, FIG.
In the second stripe St2, the end point position e_y of the effective image data area and the stripe end line position h_y are equal as described in FIG. Therefore, the process proceeds to S28.

FIG. 6 is an explanatory diagram of an example of redetermining the offset position and the effective image data length when the end point position of the effective image data area is equal to the stripe last line position. When the end point position e_y of the effective image data area is equal to the stripe end line position h_y, as can be seen from FIG. 6A, there is no line even if an attempt is made to acquire a new line below. Therefore, as shown in FIG. 6B, a line above the offset position is used for the compression processing. For this purpose, the offset position is returned by the number of missing lines, and a new offset position s_y ′ is obtained by Expression 5. Further, in order to include the missing line number in the effective image data area, a new effective image data length l_y ′ calculated by Expression 3 is applied. In this way, the length of the effective image data area is set to match the multiple of the number of lines in the compression processing unit, and the compression processing can be performed.

FIG. 7 is an explanatory diagram showing an example of redetermining the effective image data length when the end point position of the effective image data area is not equal to the stripe last line position. End point position e_y of effective image data area and stripe end line position h
As an example in which _y is not equal, the fourth stripe St4 in FIG. 3A will be described. In the case of this stripe St4, as shown in FIG. 7A, the offset position is the stripe start position. Therefore, when the effective image data length l_y does not match the multiple of the compression processing unit c, the offset position cannot be shifted as in the case shown in FIG. However, it is possible to extend the effective image data area in the sub-scanning direction. Therefore, FIG.
As shown in (B), a new effective image data length l_y ′ calculated by Expression 3 is applied to shift the end position of the effective image data area in the sub-scanning direction. In this way, the length of the effective image data area is set to match the multiple of the number of lines in the compression processing unit, and the compression processing can be performed.

As described above, in the first embodiment,
When compressing only the effective image data area in each stripe after the stripe division, if the effective image data area does not match the compression processing unit and the end position of the effective image data area matches the stripe boundary position, Since the offset position is moved in the direction opposite to the sub-scanning direction, there is no inconvenience caused by inconsistency with the processing unit in the compression processing. In addition, by performing such processing, it is possible to prevent inconsistency at the stripe boundary and maintain image quality. Furthermore, it is possible to realize with such a simple configuration, it is possible to correspond to an image data of an arbitrary stripe length and an arbitrary effective image data length with a small amount of memory, and it is also possible to correspond to an arbitrary compression method. is there.

When the offset position is different from the stripe start position and the end point position of the effective image data area is different from the stripe end line position as in the first stripe St1 in FIG. 3A, for example. In this example, as shown in FIG. 7, the effective image data length is reset without shifting the offset position. However, the present invention is not limited to this, and as shown in FIG. 6, the offset position can be shifted and the effective image data length can be reset. Alternatively, the effective image data length may be adjusted by combining the two, shifting the offset position, and shifting the end point position of the effective image data area.

In the above description, one offset is set for each stripe, but the same processing can be performed when only one offset can be set for one image. In addition, a plurality of offsets may be set for one stripe in response to a case where a plurality of valid image data areas exist. In this case, the above-described adjustment processing can be performed for each effective image data area.

FIG. 8 is a block diagram showing a second embodiment of the present invention. In the figure, the same parts as those in FIG. 5 is a stripe length counting unit,
Reference numeral 6 denotes a storage unit. The stripe division unit 2 is the first
As in the first embodiment, the image data input from the image input unit 1 is divided into stripes. The stripe division method is not limited to the fixed-length division method, and any method can be used. For example, the original may be determined so that the stripe length is always variable. in this case,
For example, a break of an object may be detected and the boundary may be set as a stripe division boundary. Of course, the division may be always performed with a fixed stripe length for each device, each document, and each page.

The stripe length counting section 5 counts the length of the target stripe to be compressed in the sub-scanning direction. The storage unit 6 stores an image of the stripe of interest and an image of a stripe adjacent to the stripe of interest. The image of the adjacent stripe can be, for example, the image of the stripe before the stripe of interest or the image of the next stripe. In the following description, the image of the next stripe is stored as the image of the adjacent stripe.

FIG. 9 is a flowchart showing an example of the operation according to the second embodiment of the present invention. In the figure, St
n indicates the n-th stripe, and l_h indicates the stripe length of interest. MEM0 indicates a memory for storing image data in the stripe of interest, and MEM1 indicates a memory for storing image data in the next stripe. This memory is provided in the storage unit 6.

In step S41, an image is input by the image input unit 1, and in step S42, stripe division is performed by the stripe division unit 2. In S43, the variable n is initialized to 1, and the stripe of interest is set to the first stripe.

In S44, it is determined whether or not the stripe of interest is the last stripe. This determination can be made based on whether the value of the variable n is equal to the number N of all the divided stripes. If the target stripe is not the last stripe, the process proceeds to S45, and the image data in the target stripe and the image data in the next stripe are stored in the memories MEM0 and MEM1, respectively. When processing stripes in order, except for the first stripe, MEM
1 is stored in the MEM0
And newly stores the image data of the next stripe in the MEM.
1 may be stored. Of course, if memories are used alternately, there is no need to move between memories.

In step S46, the stripe length counting unit 5 counts the stripe of interest l_h for the stripe of interest stored in the memory MEM0. In S47, it is determined whether or not the counted target stripe length l_h matches a multiple of the number of lines in the compression processing unit. If they match, the process proceeds to S53, and the compression unit 4 compresses the stripe of interest Stn by a predetermined encoding method for each compression processing unit.

If the target stripe length l_h does not match the multiple of the number of lines in the compression processing unit, in step S48, the start of the memory MEM1 is set so that the target stripe length l_h is a multiple of the number of lines in the compression processing unit. , Image data for the number of missing lines is temporarily added to the memory MEM0. Then, in S53, the compression unit 4 compresses each compression processing unit using a predetermined encoding method. Memory MEM
By adding the image data from 1, compression can be performed for each compression processing unit. Since the added image data is data that originally existed, it is possible to minimize deterioration in image quality during decoding. In addition,
Since the addition of the number of missing lines does not actually change the stripe length, the added portion is discarded when decoded. Also, the memory M added to the memory MEM0
The image data of EM1 is compressed again when the next stripe becomes the target stripe.

When the compression processing of the stripe of interest is completed,
In S54, it is determined whether or not the processing has been completed for all the stripes based on whether or not the value of the variable n has become equal to the total number N of the stripes. If an unprocessed stripe remains, the value of the variable n is increased by 1 in S55, the next stripe is set as the target stripe, and the process returns to S44. In this way, the above-described processing is repeated for each stripe except the last stripe.

On the other hand, if it is determined in S44 that the target stripe is the last stripe, image data in the target stripe is stored in MEM0 in S49. When stripes are sequentially processed, the memory MEM1
Is transferred to the memory MEM0 or the memory MEM1 is
Processing can be performed assuming EM0.

In step S50, the stripe length counting unit 5 counts the target stripe length l_h of the target stripe. In step S51, the counted stripe length l_
It is determined whether or not h is a multiple of the number of lines in the compression processing unit. If so, the flow advances to S53, and the compression unit 4 compresses the last stripe for each compression processing unit using a predetermined encoding method. I do.

If the target stripe length l_h does not match the multiple of the number of lines in the compression processing unit in S51, the next stripe image does not exist any more, so that the image of the next stripe cannot be added. Therefore, S52
In step (1), white pixel data for the number of missing lines is temporarily added to MEM0 such that the target stripe length l_h is a multiple of the number of lines in the compression processing unit. The reason why the white pixel data is added here is assumed because the background color is generally a white pixel in many cases. Therefore, other background colors may be used, and processing such as repeated copying of the last line in the stripe may be performed.
If the number of lines matches the multiple of the number of lines in the compression processing unit due to the addition of the image data, in step S53, the image of the last stripe to which the image data has been added is compressed by the compression unit 4 for each compression processing unit using a predetermined encoding method. I do.

After the compression processing of the last stripe, it is determined in S54 that all stripes have been processed, and the processing shown in FIG. 9 is completed.

An example of the operation in the second embodiment will be described using a specific example. Here, as an example,
A case where the image shown in FIG. 2 is divided into stripes and compressed as shown in FIG. 3B will be described. FIG.
For each stripe divided as shown in (B),
The processing of S44 to S53 is performed in order.

As described above, in S45, the images of the stripe of interest and the next stripe are stored in the memories MEM0 and ME.
Store it in M1. FIG. 10 is an explanatory diagram of an example of the image data stored in the storage unit 6. Here, a case is shown in which the fourth stripe St4 in FIG. 3B is used as the target stripe, and the image data of the stripe St4 is stored in the memory MEM0. Further, the next fifth stripe St5 is stored in the memory MEM1.

In step S46, the target stripe stored in the memory MEM0, that is, the target stripe length l_h of the fourth stripe St4 is counted. In step S47, the target stripe length l_h matches the multiple of the number of lines in the compression processing unit. Is determined. Here, it is assumed that they do not match.

FIG. 11 is an explanatory diagram in the case where the image of the next stripe is added to the stripe of interest. The stripe length when the stripe division is performed in the stripe division section 2 is arbitrary. Therefore, as shown on the left side of FIG. 11A, a case may occur in which the target stripe length l_h of the target stripe stored in the memory MEM0 is a multiple of the number of lines in the compression processing unit. In such a case, FIG.
As shown in FIG. 1B, image data for the number of missing lines from the beginning of the next stripe image stored in the memory MEM1 is temporarily added to the image in the memory MEM0.
As a result, the target stripe length l_h is a multiple of the number of lines in the compression processing unit, and the compression unit 4 can perform normal compression processing. Further, deterioration of the decoded image can be suppressed.

The image added to the memory MEM0 is
It is not cut out from the memory MEM1, but is used by copying or referring. After decoding, it is discarded without being used as an image of the stripe of interest. This part is compressed when compressing the stripe stored in the memory MEM1.

Of course, if the target stripe length l_h is a multiple of the number of lines in the compression processing unit,
What is necessary is just to compress in the compression part 4 for every compression processing unit by a predetermined encoding system.

In the above-described operation example and specific example, when the target stripe length l_h is not a multiple of the number of lines in the compression processing unit, the image is compressed by adding an image of the insufficient number of lines from the next stripe. However, the present invention is not limited to this. For example, it is also possible to add and compress an image of the number of lines insufficient from the previous stripe. FIG. 12 is an explanatory diagram in the case where an image of the previous stripe is added to the target stripe.
In this case, the memory MEM1 stores the stripe image before the stripe of interest. As shown on the left side of FIG. 12A, it is assumed that the target stripe length l_h of the target stripe stored in the memory MEM0 is different from a multiple of the number of lines in the compression processing unit. In this case, FIG.
As shown in (B), image data for the number of missing lines from the end of the previous stripe image stored in the memory MEM1 is temporarily added to the beginning of the image in the memory MEM0. As a result, the target stripe length l_h is a multiple of the number of lines in the compression processing unit, and the compression unit 4 can perform normal compression processing. Further, deterioration of the decoded image can be suppressed.

As described above, even if the stripe before the stripe of interest is stored in the storage unit 6 and the image data for the number of missing lines is added to the stripe of interest, the image data of the next stripe described above is used. As in the case, a compression process can be performed.

As described above, in the second embodiment, when compressing the image data in each stripe after the stripe division, if the stripe length does not match the compression processing unit, the stripe length is reduced by the compression processing. Pixel data corresponding to the number of missing lines from the start line of the next stripe or the previous end line is temporarily added to the image data of the target stripe so as to match the unit, and encoding processing is performed. As a result, a problem such as an error occurring during the compression processing because the number of lines does not match does not occur. In general, when an image that does not match the compression processing unit is automatically compressed, arbitrary data is often added to an arbitrary position, and inconsistency is likely to occur at a stripe boundary after decoding. However, by using the method described in the second embodiment, it is possible to prevent inconsistency at the stripe boundary and to maintain the image quality after decoding. Further, the present invention can be realized with the simple configuration as described above, and can cope with image data having an arbitrary stripe length and an arbitrary compression method.

Note that the method described in the second embodiment can be applied to the case where the offset processing described in the first embodiment is performed, and can be used in combination.

In the above-described first and second embodiments, it is assumed that stripe division is performed in the sub-scanning direction. However, in the case where stripe division is performed in the main scanning direction, or in the case where division is performed in both directions. Can be performed in the same manner.

[0056]

As is apparent from the above description, according to the present invention, when a stripe-divided image is compressed,
If the image data in the stripe to be compressed does not match the multiple of the compression processing unit, move the offset position or add appropriate data to the appropriate position to match the compression processing unit, and perform compression. Do. by this,
The compression processing can be performed normally, and there is the effect that the image quality can be maintained without inconsistency in the stripe boundary portion after decoding and stripe synthesis.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of an image.

FIG. 3 is an explanatory diagram of an example of stripe division.

FIG. 4 is a flowchart illustrating an example of an operation according to the first exemplary embodiment of the present invention.

FIG. 5 is an explanatory diagram of an example of an offset position and an effective image data length.

FIG. 6 is a diagram illustrating an example of redetermining an offset position and an effective image data length when the end point position of the effective image data area is equal to the stripe last line position.

FIG. 7 is a diagram illustrating an example of redetermining the effective image data length when the end point position of the effective image data area is not equal to the stripe last line position.

FIG. 8 is a block diagram showing a second embodiment of the present invention.

FIG. 9 is a flowchart illustrating an example of an operation according to the second exemplary embodiment of the present invention.

FIG. 10 is an explanatory diagram of an example of image data stored in a storage unit 6;

FIG. 11 is an explanatory diagram of a case where an image of the next stripe is added to a target stripe.

FIG. 12 is an explanatory diagram in a case where an image of a previous stripe is added to a target stripe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image input part, 2 ... Stripe division part, 3 ... Offset processing part, 4 ... Compression part, 5 ... Stripe length counting part, 6 ...
Storage unit, 11 background part, 12 character part, 13 photo part.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Saito 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. 72) Inventor Hideki Baba 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Kunikazu Ueno 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. PP29 PP30 RC09 TA01 TA08 TB06 TC31 UA02 UA31 5C078 AA04 BA42 CA34

Claims (8)

[Claims] 1. A stripe dividing unit for dividing an input image into stripe images, an offset processing unit for detecting a starting point of an effective image in the input image and setting the offset as an offset, and the stripe image divided by the stripe dividing unit Compression means for compressing the stripe image for each predetermined processing unit with the offset set by the offset processing means as a starting point, wherein the offset means is a compression target after the offset in each stripe image to be compressed by the compression means. If the area does not become a multiple of the processing unit of the compression by the compression means, a position before the start point of the effective image is set as an offset. 2. A stripe division unit for dividing an input image into stripe images, a compression unit for compressing the stripe image for each predetermined processing unit for each of the stripe images divided by the stripe division unit, and the compression unit Storage means for storing a stripe image adjacent to the stripe image compressed in step (b), and stripe length detection means for detecting the length of the stripe image divided by the stripe division means. If the area of the stripe image to be processed is not a multiple of the compression processing unit, the image is compressed including a part of the stripe image stored in the storage unit. 3. The storage means stores a stripe image next to the stripe image compressed by the compression means.
The compression unit performs compression using the next stripe image stored in the storage unit for the number of lines that are insufficient when compressing the compressed stripe image for each processing unit. The image processing device according to claim 2. 4. The storage means stores a stripe image before a stripe image compressed by the compression means,
The compression unit performs compression using the previous stripe images stored in the storage unit for the number of lines that are insufficient when compressing the compressed stripe image for each processing unit. The image processing device according to claim 2. 5. A stripe division step of dividing an input image into stripe images, an offset processing step of detecting a start point of an effective image in the input image and setting the offset as an offset, and the stripe image divided in the stripe division step And a compression step of compressing the stripe image for each predetermined processing unit with the offset set in the offset processing step as a starting point, wherein the offset processing step includes compression after the offset in each stripe image compressed in the compression step. If the target area is not a multiple of the compression processing unit in the compression step, a position before the start point of the effective image is set as an offset. 6. A stripe dividing step of dividing an input image into stripe images, compressing the stripe image in a predetermined processing unit for each of the stripe images divided in the stripe dividing step, and An image processing method, comprising: when a region of a stripe image is not a multiple of a compression processing unit, compressing a stripe image to be compressed including a stripe image adjacent thereto. 7. In the compression step, when the number of lines of the stripe image to be compressed is not a multiple of the number of lines of the compression processing unit, when compressing the processing unit including the last line of the stripe image, 7. The image processing method according to claim 6, wherein the compression is performed including an image corresponding to the number of insufficient lines in the next stripe image. 8. In the compression step, when the number of lines of a stripe image to be compressed is not a multiple of the number of lines of a compression processing unit, when compressing a processing unit including a leading line of the stripe image, 7. The image processing method according to claim 6, wherein the compression is performed including images of the number of insufficient lines among the previous stripe images.