WO2014030485A1 - Image compression device, operation control method therefor, and operation program therefor - Google Patents

Image compression device, operation control method therefor, and operation program therefor Download PDF

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Publication number
WO2014030485A1
WO2014030485A1 PCT/JP2013/070164 JP2013070164W WO2014030485A1 WO 2014030485 A1 WO2014030485 A1 WO 2014030485A1 JP 2013070164 W JP2013070164 W JP 2013070164W WO 2014030485 A1 WO2014030485 A1 WO 2014030485A1
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Prior art keywords
image
compression
data amount
page
frame
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PCT/JP2013/070164
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French (fr)
Japanese (ja)
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野中　俊一郎
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富士フイルム株式会社
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Priority to JP2014531553A priority Critical patent/JP5947384B2/en
Publication of WO2014030485A1 publication Critical patent/WO2014030485A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/189—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding
    • H04N19/192—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding the adaptation method, adaptation tool or adaptation type being iterative or recursive
    • H04N19/194—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding the adaptation method, adaptation tool or adaptation type being iterative or recursive involving only two passes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/124—Quantisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/146—Data rate or code amount at the encoder output
    • H04N19/15—Data rate or code amount at the encoder output by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field

Definitions

  • the present invention relates to an image compression apparatus, an operation control method thereof, and an operation program thereof.
  • Patent Document 1 When compressing image data, encoding is performed while continuing to input the image data (Patent Document 1), so that the image size of each page is constant in the image data in which each page is divided into a plurality of blocks. There are those that do (Patent Document 2), those that compress images at a compression rate set by the user (Patent Document 3), and those that prevent a reduction in the speed of continuous recording (Patent Document 4).
  • JP 2004-312180 A JP 2004-159069 A JP-A-6-326872 JP-A-6-654309
  • An object of the present invention is to make the image quality of each page of an image group such as a cartoon, a photo book, and a photo book (photo album) equal.
  • the compression apparatus includes a first compression rate at which each page image of an image group composed of a plurality of page images has an image quality equal to or higher than a predetermined minimum image quality.
  • the first compression means for performing the first compression processing using the initial compression ratio between the second compression ratio in which the data amount of the compressed image group is equal to or less than the predetermined overall target data amount , And the second compression processing is performed in order of decreasing data amount after compression of the page images constituting the image group compressed by the first compression means, and the nth (n is an integer of 1 or more) th
  • the page image target data amount for the page image is [(total target data amount) ⁇ ⁇ total data amount when the second compression processing is performed for the (n ⁇ 1) th page images ⁇ ] ⁇ (First compression process Data amount of the nth page image obtained in step) / [(data amount of the entire image group obtained in the first compression processing) ⁇ ⁇ (n ⁇ 1) th obtained in the first compression processing)
  • Second compression means for performing the second compression processing so that
  • the present invention also provides an operation control method suitable for an image compression apparatus.
  • the first compression means has the image quality of the page group of the image group composed of a plurality of page images, and the compressed page image has an image quality higher than the predetermined minimum image quality.
  • the first compression processing is performed using an initial compression ratio between the first compression ratio and a second compression ratio at which the data amount of the compressed image group is equal to or less than a predetermined overall target data amount.
  • the second compression means performs the second compression processing in order from the smallest data amount after compression of the page images constituting the image group compressed by the first compression means, and the nth page
  • the page image target data amount for the image is [(total target data amount) ⁇ ⁇ total data amount when the second compression processing is performed for the (n ⁇ 1) th page images ⁇ ] ⁇ (first Obtained in 1 compression process Data amount of the n-th page image) / [(data amount of the entire image group obtained in the first compression processing) ⁇ ⁇ up to (n ⁇ 1) -th obtained in the first compression processing]
  • the second compression process is performed so that the total data amount of the page image ⁇ is obtained.
  • the present invention also provides a computer-readable program for controlling the operation of the image compression apparatus.
  • a recording medium storing such a program may be provided.
  • each of the page images constituting the image group has the first compression rate at which the image quality exceeds the minimum image quality, and the second compression at which the data amount of the image group after compression is equal to or less than the total target data amount.
  • the first compression processing is performed using an initial compression ratio between the ratios.
  • the second compression processing is performed in ascending order of the data amount after compression of the first compression processing.
  • the second compression process is performed according to the ratio between the data amount of the entire image group after the first compression process and the total target data amount, the first compression process and the second compression process are performed.
  • the data amount of the subsequent image group becomes the total target data amount, and the image quality of all the page images constituting the image group becomes relatively uniform.
  • the second compression unit may increase the target data amount of the page image by a predetermined ratio, for example, when the second compression processing that becomes the page image target data amount cannot be performed.
  • the second compression means for example, the m-th image in order of decreasing (data amount of frame / area of frame) after the first compression processing.
  • the frame image target data amount for the frame image is [(page image target data amount) ⁇ ⁇ total data amount of the frame image when the second compression processing is performed for the (m ⁇ 1) th frame images. ⁇ ] ⁇ (data amount of the m-th frame image data obtained in the first compression process) / [(data amount of the page image obtained in the first compression process) ⁇ ⁇ in the first compression process
  • the second compression processing may be performed for each frame so that the total data amount of the obtained (m ⁇ 1) th frame image ⁇ .
  • the second compression means may perform the second compression process at the same compression rate for the spread page image, for example, in response to the frame being allocated over the spread page image.
  • the second compression means is assigned to the first page image in response to the fact that frames are assigned over the spread page image composed of the first page image and the second page image in succession.
  • the second compression processing may be performed by regarding the first frame portion and the second frame portion allocated to the second page image as separate frames.
  • the second compression means is assigned to the first page image in response to the fact that frames are assigned over the spread page image composed of the first page image and the second page image in succession.
  • the second compression process may be performed so that the compression rate of the first frame portion and the compression rate of the second frame portion assigned to the second page image are the same.
  • FIG. 1 shows an embodiment of the present invention, and is a block diagram showing an electrical configuration of a comic image compression apparatus 1.
  • the overall operation of the comic image compression apparatus 1 is controlled by the CPU 2.
  • the comic image compression apparatus 1 includes a communication interface 3 for connecting to a network such as the Internet, a memory 4 for storing data, a display device 5 for displaying comic images, and an input device 6 such as a keyboard.
  • the comic image compression apparatus 1 also includes a hard disk 8, a hard disk drive 7 that accesses the hard disk 8, and a CD-ROM (compact disk-read only memory) drive 9.
  • a CD-ROM 10 storing a program for controlling operations described later is read by the CD-ROM drive 9
  • the read program is installed in the comic image compression apparatus 1.
  • the program may be recorded on a recording medium other than the CD-ROM 10, and may be read from such a recording medium and installed in the comic image compression apparatus 1.
  • the program may be transmitted to the comic image compression apparatus 1 via the Internet or the like, and the program received via the communication interface 3 may be installed in the comic image compression apparatus 1.
  • the comic image compression apparatus 1 can be configured using a computer.
  • Fig. 2 shows a comic image composed of 10 pages of page images.
  • the comic image is composed of ten page images 31 to 40 from the first page image 31 to the tenth page image 40.
  • the comic image may be composed of page images less than 10 page images, or may be composed of more page images than 10 page images.
  • the data amount of each page image from the first page image 31 to the tenth page image 40 is 10 MB.
  • the total data amount of comic images is 100 MB.
  • the image quality of each page image from the first page image 31 to the tenth page image 40 is made as uniform as possible, and the total data amount of the comic images is the target data amount (total target data amount).
  • the comic image is compressed so as to be 20 MB.
  • FIG. 3 is a flowchart showing the processing procedure of the comic image compression apparatus 1.
  • JPEG Joint Photographic Experts Group
  • an image is divided into blocks of 8 pixels ⁇ 8 pixels, and converted from the spatial domain to the frequency domain using discrete cosine transform in units of blocks.
  • the converted data is subjected to entropy coding using Huffman codes after the amount of data is reduced by quantization.
  • a parameter used in quantization is called a Q value, and the amount of data after compression changes depending on the value of the Q value.
  • the first Q value is such that the image quality after compression of each of the plurality of page images 31 to 40 is equal to or higher than a predetermined minimum image quality.
  • First compression rate and a second Q value (second compression rate) at which the total data amount of the compressed comic image is equal to or less than a predetermined overall target data amount (for example, 20 MB)
  • the initial Q value is determined. Using such initial Q value, the page images of all the page images 31 to 40 constituting the comic image are compressed (first compression process) (step 21).
  • FIG. 4 shows a comic image after the first compression processing.
  • the data amount of the first page image 31 and the data amount of the third page image 33 are both 0.5 MB
  • the data amount of the second page image 32 is 1 MB
  • the data amount of the page image 40 is 2 MB.
  • Other page images are also smaller than the data amount before the first compression processing.
  • the amount of data after the first compression processing is different for each page image because the density of the cartoon is different for each page image.
  • a fine page image has a larger amount of data after the first compression process than a non-fine page image.
  • the entire data amount of the comic image is 10 MB as a result of the first compression process.
  • This total data amount of 10 MB is smaller than the total target data amount of 20 MB.
  • the page images 31 to 40 are rearranged in order of decreasing data amount after the first compression processing (step 22 in FIG. 3). Rearrangement is performed so that a page image with a small amount of data after the first compression processing is preferentially subjected to second compression processing described later.
  • FIG. 5 shows the rearranged page images 31-40.
  • page images are arranged from the left side in ascending order of data amount after the first compression processing.
  • Page images with the same amount of data after the first compression processing are arranged so that the page image of the previous page is on the left side (first), but is arranged so that the page image of the subsequent page is on the left side. It may be done.
  • the first page image 31 with a data amount of 0.5 MB is arranged at the very beginning (leftmost), and then the third page image 33 with a data amount of 0.5 MB is arranged.
  • the second page image 32 having a data amount of 1 MB is arranged.
  • the fourth and subsequent page images (not shown) are also arranged in ascending order of data amount after the first compression processing.
  • the 10th page image 40 having a data amount of 2 MB is arranged.
  • the n-th (n is an integer equal to or greater than 1) -th page image is compressed so that the data amount (page target data amount) based on the arithmetic expression of Equation 1 is obtained. (Second compression process) (Step 23 in FIG. 3).
  • FIG. 6 shows a state in which the first page image 31 is subjected to the second compression processing according to Equation 1.
  • the second compression processing is performed for the page images up to (n ⁇ 1) th in the equation 1.
  • the total data amount at the time when the image data is performed ⁇ and ⁇ the total data amount of the (n ⁇ 1) th page images obtained in the first compression process ⁇ are both 0.
  • the second compression process the data amount of the first page image subjected to the first compression process is doubled.
  • the second compression process may be performed such that the data amount matches the data amount obtained based on Equation 1, but it may not.
  • the data amount obtained based on Equation 1 is set to a predetermined value.
  • the nth page image is compressed so that the data amount is close to the data amount multiplied by the ratio (for example, 1.1) (step 25).
  • step 23 and step 24 are performed for all page images (the processing of step 25 is also performed as necessary) (step 26). If the processing in step 23 and the like has not been completed for all page images, n is incremented (step 27), and the processing from step 23 is repeated again.
  • FIG. 7 shows a state in which the second page image 33 is subjected to the second compression processing according to Equation 1.
  • the same processing is repeated for the third and subsequent page images.
  • the image quality of the page image after the second compression processing is relatively uniform.
  • the data amount of the entire comic image after the second compression processing is close to the target data amount.
  • FIG. 8 is an example of page images 31 to 40 rearranged after the first compression processing, and corresponds to FIG.
  • the page images 31 to 40 are rearranged in ascending order of the amount of data after compression.
  • a frame may be formed across the two-page spread image.
  • rearrangement is defined so as to be continuous.
  • the data amount of both the first page image 31 and the third page image 33 after the first compression processing is 0.5 MB
  • the data amount of the second page image 32 after the first compression processing is 1 MB.
  • the first page image 31, the third page image 33, and the second page image 32 are rearranged in order of decreasing data amount.
  • the frame is formed over the page image 32, the first page image 31 and the second page image are formed even though the data amount of the second page image 32 is smaller than the data amount of the third page image 33. 32 is continuous.
  • the second compression processing described above may be performed by rearranging the page images in which the frames are formed over the spread so as to be continuous. Furthermore, when a frame is allocated over spread page images, these spread page images may be compressed with the same Q value (compression ratio). Data indicating whether or not a frame is formed over the spread page is stored in advance in the header of the file representing the cartoon image, and the frame is formed on the spread page by referring to the data. Needless to say.
  • the above-described compression process is performed for each frame included in the page image.
  • the first compression processing is performed with the initial Q value for all page images constituting the comic image (step 51).
  • FIG. 11 shows an example of the first page image 31 that has been subjected to the first compression processing.
  • the data amount of the first page image 31 on which the first compression processing has been performed is 0.5 MB as described above.
  • the first page image 31 includes six frames from the first frame 71 to the sixth frame 76.
  • the amount and the data amount of the sixth frame 76 are 0.5 MB, 0.07 MB, 0.12 MB, 0.02 MB, 0.11 MB, and 0.08 MB, respectively.
  • FIG. 12 is an example of a frame table for the first page image 31.
  • a frame table is similarly formed for the page images constituting the comic image other than the first page image 31.
  • the frame table columns of frame number, coordinates, area, and data amount are formed.
  • the frame number identifies a frame included in the page image.
  • Frame numbers 1, 2, 3, 4, 5, and 6 are respectively the first frame 71, the second frame 72, the third frame 73, the fourth frame 74, the fifth frame 75, and the sixth frame. It corresponds to frame 76.
  • the coordinates indicate the position of each frame in the page image. Since the frames 71 to 76 constituting the first page image 31 are quadrangles, the positions of the frames 71 to 76 are specified by representing the vertices of the quadrangles with coordinates. For example, the upper left (upper right) of the first page image 31 is the origin. The area is the area of each frame.
  • the data amount is the data amount of each frame on which the first compression processing has been performed. These coordinates, area, and data amount are stored in the frame table corresponding to the frame number. By storing the frame table in the memory 4 of the comic image compression apparatus 1, the coordinates and the like are stored in the comic image compression apparatus 1 for each frame.
  • the frame images constituting the first compressed page image are rearranged in the ascending order of (frame data amount / frame area) (step 53 in FIG. 9).
  • FIG. 13 shows an example of the frame images rearranged in ascending order of (frame data amount / frame area).
  • the page images are rearranged in the order of the data amount of the page image after the first compression processing.
  • the frame images are represented by (frame data amount / frame area). ) In ascending order. This is because the second compression process is preferentially performed for frames with a small amount of data per unit area.
  • the second frame 72, the fourth frame 74, the sixth frame 76, the fifth frame 75, the third frame 73, and the first frame are in order of increasing (data amount of frame / area of frame).
  • One frame 71 is arranged.
  • the mth ((frame image target data amount)) becomes the data amount (the frame image target data amount) based on the arithmetic expression of Equation 2 in the order of decreasing (frame data amount / frame area).
  • the m-th frame image is compressed (second compression processing) (step 54 in FIG. 9).
  • FIG. 14 shows a state in which the first frame image 72 is subjected to the second compression processing according to Equation 2.
  • the second compression process may be performed such that the data amount matches the data amount obtained based on Equation 2, but it may not be possible.
  • the m-th frame image is compressed so as to obtain a data amount in the vicinity of the data amount obtained by multiplying the obtained data amount by a predetermined ratio (for example, 1.1) (step 56).
  • step 54 and step 55 is performed for all the frame images (the processing of step 56 is also performed if necessary) (step 57). If the processing in step 54 and the like has not been completed for all the frame images, m is incremented (step 58), and the processing from step 54 is repeated again.
  • FIG. 15 shows a state in which the second frame image 74 is subjected to the second compression processing in accordance with Equation 2.
  • the same processing is repeated for the third and subsequent page images.
  • the image quality of the frame image after the second compression processing is relatively uniform within the page image.
  • step 59 in FIG. 10 it is confirmed whether or not the processing has been completed for all page images. If not completed (NO in step 59 in FIG. 10), n is incremented (step 60 in FIG. 10), and the processing from step 52 in FIG. 9 is repeated for the next page image.
  • FIG. 16 is an example of a page image showing a frame formed over a spread page.
  • the right side is the first page image 101 and the left side is the second page image 102.
  • frames 81 to 85 are formed, and in the second page image 102, frames 91 to 95 are formed.
  • a frame 90 is formed across the first page image 101 and the second page image 102.
  • the frame portion 90A included in the first page image 101 and the frame portion 90B included in the second page image 102 are regarded as separate frames, and the above-described processing is performed. You may make it perform. Further, the Q value of the frame portion 90A and the Q value of the frame portion 90B may be the same.
  • the second compression processing is performed for each frame image so that all the page images constituting the comic image are rearranged for each frame image, and the data amount after the second compression processing becomes the total target data amount. You may be made to be.
  • comic images have been described. Needless to say, the present invention can be applied not only to comic images but also to image groups such as photo books and photo books (photo albums) composed of a plurality of page images. Nor.
  • 1 cartoon image compression device 2 CPU 31-40, 101, 102 page images 71-76, 81-85, 90-95 frames

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Abstract

The purpose of the invention is to make image quality uniform among pages. A first compression process is applied, using an initial Q factor, to each page image of a comics image formed of a plurality of page images (31-40). A second compression process is applied to the n-th page image in ascending order of the data amounts, after compression, of the page images constituting the comics image to which the first compression process has been applied, such that the target page image data amount is equal to [(overall target data amount) − (total data amount obtained when the second compression process has been applied to page images up to the (n−1)-th page image)] × (data amount of the n-th page image obtained in the first compression process)/[(data amount of the overall comics image obtained in the first compression process) − (total data amount of page images up to the (n−1)-th page image obtained in the first compression process)].

Description

画像圧縮装置ならびにその動作制御方法およびその動作プログラムImage compression apparatus, operation control method thereof, and operation program thereof
　この発明は，画像圧縮装置ならびにその動作制御方法およびその動作プログラムに関する。 The present invention relates to an image compression apparatus, an operation control method thereof, and an operation program thereof.
　電子化された漫画をスマートフォンに代表される携帯電話に送信することにより，携帯電話の表示画面などに漫画を表示できるようになってきている。電子化された漫画を圧縮せずに送信するとデータ量が多いので，電子化された漫画全体のデータ量が所定のデータ量以下となるように圧縮することが多い。 漫画 By sending digitized comics to mobile phones such as smartphones, it has become possible to display comics on the display screen of mobile phones. Since the amount of data is large when an electronic comic is transmitted without being compressed, it is often compressed so that the total data amount of the electronic comic is less than a predetermined data amount.
　画像データを圧縮する場合に，画像データの入力を継続しながら符号化するもの（特許文献１），各ページが複数のブロックに分割された画像データにおいて各ページの画像サイズが一定となるようにするもの（特許文献２），ユーザが設定した圧縮率で画像を圧縮するもの（特許文献３），連続記録のスピードの低下を防止するもの（特許文献４）などがある。 When compressing image data, encoding is performed while continuing to input the image data (Patent Document 1), so that the image size of each page is constant in the image data in which each page is divided into a plurality of blocks. There are those that do (Patent Document 2), those that compress images at a compression rate set by the user (Patent Document 3), and those that prevent a reduction in the speed of continuous recording (Patent Document 4).
特開2004-312180号公報JP 2004-312180 A 特開2004-159069号公報JP 2004-159069 A 特開平6-326872号公報JP-A-6-326872 特開平6-654309号公報JP-A-6-654309
　電子化された漫画を圧縮する場合，漫画の緻密さはすべてのページにおいて均一ではないので，すべてのページを一律の圧縮率で圧縮するとページごとに画質の違いが目立ってしまうことがある。 When compressing digitized comics, the density of comics is not uniform across all pages, so if all pages are compressed with a uniform compression ratio, differences in image quality may be noticeable from page to page.
　この発明は，漫画，写真集，フォト・ブック（フォト・アルバム）などの画像群のページごとの画質が等しくなるようにすることを目的とする。 An object of the present invention is to make the image quality of each page of an image group such as a cartoon, a photo book, and a photo book (photo album) equal.
　この発明による圧縮装置は，複数のページ画像から構成される画像群のそれぞれのページ画像を，圧縮後のそれぞれのページ画像があらかじめ定められている最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量があらかじめ定められている全体目標データ量以下となる第２の圧縮率と，の間の初期圧縮率を用いて第１の圧縮処理を行う第１の圧縮手段，および第１の圧縮手段によって圧縮された画像群を構成するページ画像の圧縮後のデータ量の少ない順に第２の圧縮処理を行うものであって，第ｎ（ｎは１以上の整数）番目のページ画像についてのページ画像目標データ量が，［（全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（第１の圧縮処理において得られた画像群全体のデータ量）－｛第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように第２の圧縮処理を行う第２の圧縮手段を備えていることを特徴とする。 The compression apparatus according to the present invention includes a first compression rate at which each page image of an image group composed of a plurality of page images has an image quality equal to or higher than a predetermined minimum image quality. The first compression means for performing the first compression processing using the initial compression ratio between the second compression ratio in which the data amount of the compressed image group is equal to or less than the predetermined overall target data amount , And the second compression processing is performed in order of decreasing data amount after compression of the page images constituting the image group compressed by the first compression means, and the nth (n is an integer of 1 or more) th The page image target data amount for the page image is [(total target data amount) − {total data amount when the second compression processing is performed for the (n−1) th page images}] × (First compression process Data amount of the nth page image obtained in step) / [(data amount of the entire image group obtained in the first compression processing) − {(n−1) th obtained in the first compression processing) Second compression means for performing the second compression processing so that the total data amount of the page image up to the th} is obtained.
　この発明は，画像圧縮装置に適した動作制御方法も提供している。すなわち，この方法は，第１の圧縮手段が，複数のページ画像から構成される画像群のそれぞれのページ画像を，圧縮後のそれぞれのページ画像があらかじめ定められている最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量があらかじめ定められている全体目標データ量以下となる第２の圧縮率との間の初期圧縮率を用いて第１の圧縮処理を行い，第２の圧縮手段が，第１の圧縮手段によって圧縮された画像群を構成するページ画像の圧縮後のデータ量の少ない順に第２の圧縮処理を行うものであって，第ｎ番目のページ画像についてのページ画像目標データ量が，［（全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（第１の圧縮処理において得られた画像群全体のデータ量）－｛第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように第２の圧縮処理を行うものである。 The present invention also provides an operation control method suitable for an image compression apparatus. In other words, in this method, the first compression means has the image quality of the page group of the image group composed of a plurality of page images, and the compressed page image has an image quality higher than the predetermined minimum image quality. The first compression processing is performed using an initial compression ratio between the first compression ratio and a second compression ratio at which the data amount of the compressed image group is equal to or less than a predetermined overall target data amount. , The second compression means performs the second compression processing in order from the smallest data amount after compression of the page images constituting the image group compressed by the first compression means, and the nth page The page image target data amount for the image is [(total target data amount) − {total data amount when the second compression processing is performed for the (n−1) th page images}] × (first Obtained in 1 compression process Data amount of the n-th page image) / [(data amount of the entire image group obtained in the first compression processing) − {up to (n−1) -th obtained in the first compression processing] The second compression process is performed so that the total data amount of the page image} is obtained.
　この発明は，画像圧縮装置の動作を制御するコンピュータが読み取り可能なプログラムも提供している。そのようなプログラムを格納した記録媒体を提供するようにしてもよい。 The present invention also provides a computer-readable program for controlling the operation of the image compression apparatus. A recording medium storing such a program may be provided.
　この発明によると，画像群を構成するページ画像のそれぞれが，最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量が全体目標データ量以下となる第２の圧縮率と，の間の初期圧縮率を用いて第１の圧縮処理が行われる。第１の圧縮処理が行われた画像群を構成する複数のページ画像については，第１の圧縮処理の圧縮後のデータ量の少ない順に第２の圧縮処理が行われる。この第２の圧縮処理は，第ｎ（ｎは１以上の整数）番目のページ画像のデータ量が，（全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（第１の圧縮処理において得られた画像群全体のデータ量）－｛第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように行われる。 According to the present invention, each of the page images constituting the image group has the first compression rate at which the image quality exceeds the minimum image quality, and the second compression at which the data amount of the image group after compression is equal to or less than the total target data amount. The first compression processing is performed using an initial compression ratio between the ratios. For a plurality of page images constituting the image group on which the first compression processing has been performed, the second compression processing is performed in ascending order of the data amount after compression of the first compression processing. In the second compression processing, the data amount of the n-th (n is an integer equal to or greater than 1) -th page image is equal to (total target data amount)-{second (n-1) -th page image. Total amount of data when compression processing is performed}] × (data amount of nth page image obtained in first compression processing) / [(total image group obtained in first compression processing) (Data amount) − {total data amount of the page images up to (n−1) th obtained in the first compression processing}.
　この発明によると，第１の圧縮処理後の画像群全体のデータ量と全体目標データ量との比率に応じて第２の圧縮処理が行われるので，第１の圧縮処理および第２の圧縮処理後の画像群のデータ量は全体目標データ量となり，かつ画像群を構成する複数のページ画像のすべての画質が比較的均一となる。 According to the present invention, since the second compression process is performed according to the ratio between the data amount of the entire image group after the first compression process and the total target data amount, the first compression process and the second compression process are performed. The data amount of the subsequent image group becomes the total target data amount, and the image quality of all the page images constituting the image group becomes relatively uniform.
　第２の圧縮手段は，たとえば，ページ画像目標データ量となるような第２の圧縮処理ができない場合にはページ画像の目標データ量を所定割合だけ大きくするものでもよい。 The second compression unit may increase the target data amount of the page image by a predetermined ratio, for example, when the second compression processing that becomes the page image target data amount cannot be performed.
　ページ画像に，複数のコマが割り当てられている場合には，第２の圧縮手段は，たとえば，第１の圧縮処理後の（コマのデータ量／コマの面積）が少ない順に，第ｍ番目のコマ画像についてのコマ画像目標データ量が，［（ページ画像目標データ量）－｛第（ｍ－１）番目までのコマ画像について第２の圧縮処理が行われたときのコマ画像の総データ量｝］×（第１の圧縮処理において得られた第ｍ番目のコマ画像データのデータ量）／［（第１の圧縮処理において得られたページ画像のデータ量）－｛第１の圧縮処理において得られた第（ｍ－１）番目までのコマ画像の総データ量｝となるようにコマごとに第２の圧縮処理を行うようにしてもよい。 When a plurality of frames are assigned to the page image, the second compression means, for example, the m-th image in order of decreasing (data amount of frame / area of frame) after the first compression processing. The frame image target data amount for the frame image is [(page image target data amount) − {total data amount of the frame image when the second compression processing is performed for the (m−1) th frame images. }] × (data amount of the m-th frame image data obtained in the first compression process) / [(data amount of the page image obtained in the first compression process) − {in the first compression process The second compression processing may be performed for each frame so that the total data amount of the obtained (m−1) th frame image}.
　第２の圧縮手段は，たとえば，見開きのページ画像にわたってコマが割り当てられていることに応じて，その見開きのページ画像については同じ圧縮率で第２の圧縮処理を行うものでもよい。 The second compression means may perform the second compression process at the same compression rate for the spread page image, for example, in response to the frame being allocated over the spread page image.
　第２の圧縮手段は，連続して第１のページ画像と第２のページ画像とで構成される見開きのページ画像にわたってコマが割り当てられていることに応じて，第１のページ画像に割り当てられている第１のコマ部分と第２のページ画像に割り当てられている第２のコマ部分とを別々のコマと見なして第２の圧縮処理を行うものでもよい。 The second compression means is assigned to the first page image in response to the fact that frames are assigned over the spread page image composed of the first page image and the second page image in succession. The second compression processing may be performed by regarding the first frame portion and the second frame portion allocated to the second page image as separate frames.
　第２の圧縮手段は，連続して第１のページ画像と第２のページ画像とで構成される見開きのページ画像にわたってコマが割り当てられていることに応じて，第１のページ画像に割り当てられている第１のコマ部分の圧縮率と第２のページ画像に割り当てられている第２のコマ部分の圧縮率とが同一の圧縮率となるように第２の圧縮処理を行うものでもよい。 The second compression means is assigned to the first page image in response to the fact that frames are assigned over the spread page image composed of the first page image and the second page image in succession. The second compression process may be performed so that the compression rate of the first frame portion and the compression rate of the second frame portion assigned to the second page image are the same.
漫画画像圧縮装置の電気的構成を示すブロック図である。It is a block diagram which shows the electrical structure of a comic image compression apparatus. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像圧縮装置の処理手順を示すフローチャートである。It is a flowchart which shows the process sequence of a comic image compression apparatus. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像を構成するページ画像の一例である。It is an example of the page image which comprises a comic image. 漫画画像圧縮装置の処理手順を示すフローチャートである。It is a flowchart which shows the process sequence of a comic image compression apparatus. 漫画画像圧縮装置の処理手順を示すフローチャートである。It is a flowchart which shows the process sequence of a comic image compression apparatus. ページ画像の一例である。It is an example of a page image. コマ・テーブルの一例である。It is an example of a frame table. コマ画像の一例である。It is an example of a frame image. コマ画像の一例である。It is an example of a frame image. コマ画像の一例である。It is an example of a frame image. ページ画像の一例である。It is an example of a page image.
　図１は，この発明の実施例を示すもので，漫画画像圧縮装置１の電気的構成を示すブロック図である。 FIG. 1 shows an embodiment of the present invention, and is a block diagram showing an electrical configuration of a comic image compression apparatus 1.
　漫画画像圧縮装置１の全体の動作は，ＣＰＵ２によって統括される。 The overall operation of the comic image compression apparatus 1 is controlled by the CPU 2.
　漫画画像圧縮装置１には，インターネットなどのネットワークと接続するための通信インターフェイス３，データを記憶するメモリ４，漫画画像を表示する表示装置５およびキーボードなどの入力装置６が含まれている。また，漫画画像圧縮装置１には，ハードディスク８およびハードディスク８にアクセスするハードディスク・ドライブ７ならびにCD-ROM（コンパクト・ディスク-リード・オンリ・メモリ）ドライブ９も含まれている。後述する動作を制御するプログラムが格納されているCD-ROM10がCD-ROMドライブ９によって読み取られると，読み取られたプログラムが漫画画像圧縮装置１にインストールされる。プログラムは，CD-ROM10以外の記録媒体に記録されており，そのような記録媒体から読み取られて漫画画像圧縮装置１にインストールされるようにしてもよい。また，インターネットなどを介して漫画画像圧縮装置１にプログラムを送信して，通信インターフェイス３を介して受信したプログラムが漫画画像圧縮装置１にインストールされるようにしてもよい。漫画画像圧縮装置１はコンピュータを利用して構成できる。 The comic image compression apparatus 1 includes a communication interface 3 for connecting to a network such as the Internet, a memory 4 for storing data, a display device 5 for displaying comic images, and an input device 6 such as a keyboard. The comic image compression apparatus 1 also includes a hard disk 8, a hard disk drive 7 that accesses the hard disk 8, and a CD-ROM (compact disk-read only memory) drive 9. When a CD-ROM 10 storing a program for controlling operations described later is read by the CD-ROM drive 9, the read program is installed in the comic image compression apparatus 1. The program may be recorded on a recording medium other than the CD-ROM 10, and may be read from such a recording medium and installed in the comic image compression apparatus 1. Alternatively, the program may be transmitted to the comic image compression apparatus 1 via the Internet or the like, and the program received via the communication interface 3 may be installed in the comic image compression apparatus 1. The comic image compression apparatus 1 can be configured using a computer.
　図２は，10ページ分のページ画像から構成される漫画画像を示している。 Fig. 2 shows a comic image composed of 10 pages of page images.
　漫画画像は，第１ページ画像31から第10ページ画像40までの10個のページ画像31～40で構成されている。もちろん，漫画画像は10個のページ画像未満のページ画像によって構成されていてもよいし，10個のページ画像より多くのページ画像によって構成されていてもよい。 The comic image is composed of ten page images 31 to 40 from the first page image 31 to the tenth page image 40. Of course, the comic image may be composed of page images less than 10 page images, or may be composed of more page images than 10 page images.
　第１ページ画像31から第10ページ画像40のそれぞれのページ画像のデータ量は，すべて10ＭＢであるとする。もちろん，ページ画像ごとにデータ量が異なっていてもよい。漫画画像の合計のデータ量は100ＭＢとなる。この実施例では，第１ページ画像31から第10ページ画像40のそれぞれのページ画像の画質ができるだけ均等になるように，かつ漫画画像の合計のデータ量が目標のデータ量（全体目標データ量）である20ＭＢとなるように，漫画画像を圧縮するものである。 Suppose that the data amount of each page image from the first page image 31 to the tenth page image 40 is 10 MB. Of course, the data amount may be different for each page image. The total data amount of comic images is 100 MB. In this embodiment, the image quality of each page image from the first page image 31 to the tenth page image 40 is made as uniform as possible, and the total data amount of the comic images is the target data amount (total target data amount). The comic image is compressed so as to be 20 MB.
　図３は，漫画画像圧縮装置１の処理手順を示すフローチャートである。 FIG. 3 is a flowchart showing the processing procedure of the comic image compression apparatus 1.
　この実施例では，漫画画像の圧縮はJPEG（Joint Photographic Experts Group）が利用される。JPEGでは，画像を８画素×８画素のブロックに分割し，そのブロック単位で離散コサイン変換を用いて空間領域から周波数領域へ変換される。変換されたデータが，量子化によってデータ量が落とされてから，ハフマン符号によるエントロピー符号化がなされる。量子化において利用されるパラメータがＱ値と呼ばれ，そのＱ値の値により圧縮後のデータ量が変わる。 In this embodiment, JPEG (Joint Photographic Experts Group) is used for compression of comic images. In JPEG, an image is divided into blocks of 8 pixels × 8 pixels, and converted from the spatial domain to the frequency domain using discrete cosine transform in units of blocks. The converted data is subjected to entropy coding using Huffman codes after the amount of data is reduced by quantization. A parameter used in quantization is called a Q value, and the amount of data after compression changes depending on the value of the Q value.
　まず，この実施例では，図２に示したように複数のページ画像31～40のそれぞれのページ画像の圧縮後の画質が，あらかじめ定められている最低画質以上となるような第１のＱ値（第１の圧縮率）と，圧縮後の漫画画像の合計のデータ量があらかじめ定められている全体目標データ量（例えば，20ＭＢ）以下となる第２のＱ値（第２の圧縮率）と，の間の初期Ｑ値（初期圧縮率）が決定されている。そのような初期Ｑ値を用いて，漫画画像を構成するすべてのページ画像31～40のそれぞれのページ画像が圧縮される（第１の圧縮処理）（ステップ21）。 First, in this embodiment, as shown in FIG. 2, the first Q value is such that the image quality after compression of each of the plurality of page images 31 to 40 is equal to or higher than a predetermined minimum image quality. (First compression rate) and a second Q value (second compression rate) at which the total data amount of the compressed comic image is equal to or less than a predetermined overall target data amount (for example, 20 MB) , The initial Q value (initial compression rate) is determined. Using such initial Q value, the page images of all the page images 31 to 40 constituting the comic image are compressed (first compression process) (step 21).
　図４は，第１の圧縮処理後の漫画画像を示している。 FIG. 4 shows a comic image after the first compression processing.
　第１の圧縮処理が行われたことにより，第１ページ画像31のデータ量および第３ページ画像33のデータ量はいずれも0.5ＭＢとなり，第２ページ画像32のデータ量は１ＭＢとなり，第10ページ画像40のデータ量は２ＭＢとなったものとする。その他のページ画像も第１の圧縮処理前のデータ量よりも少なくなっている。ページ画像ごとに第１の圧縮処理後のデータ量が異なっているのは，ページ画像ごとに漫画の緻密さが異なっているからである。緻密なページ画像の方が緻密でないページ画像よりも第１の圧縮処理後のデータ量が多くなっている。 As a result of the first compression processing, the data amount of the first page image 31 and the data amount of the third page image 33 are both 0.5 MB, the data amount of the second page image 32 is 1 MB, It is assumed that the data amount of the page image 40 is 2 MB. Other page images are also smaller than the data amount before the first compression processing. The amount of data after the first compression processing is different for each page image because the density of the cartoon is different for each page image. A fine page image has a larger amount of data after the first compression process than a non-fine page image.
　第１の圧縮処理が行われたことにより，漫画画像の全体のデータ量は10ＭＢとなったものとする。この全体のデータ量10ＭＢは，全体目標データ量である20ＭＢよりも少ない。 Suppose that the entire data amount of the comic image is 10 MB as a result of the first compression process. This total data amount of 10 MB is smaller than the total target data amount of 20 MB.
　第１の圧縮処理が行われると，第１の圧縮処理後のデータ量の少ない順にページ画像31～40が並び換えられる（図３ステップ22）。第１圧縮処理後のデータ量が少ないページ画像を，優先的に後述する第２の圧縮処理が行われるようにするために並び換えが行われる。 When the first compression processing is performed, the page images 31 to 40 are rearranged in order of decreasing data amount after the first compression processing (step 22 in FIG. 3). Rearrangement is performed so that a page image with a small amount of data after the first compression processing is preferentially subjected to second compression processing described later.
　図５は，並び換えられたページ画像31～40を示している。 FIG. 5 shows the rearranged page images 31-40.
　図５においては，第１の圧縮処理後のデータ量が少ない順に左側からページ画像が並べられている。第１の圧縮処理後のデータ量が同じページ画像については，先のページのページ画像が左側（先）となるように並べられているが，後のページのページ画像が左側となるように並べられていてもよい。 In FIG. 5, page images are arranged from the left side in ascending order of data amount after the first compression processing. Page images with the same amount of data after the first compression processing are arranged so that the page image of the previous page is on the left side (first), but is arranged so that the page image of the subsequent page is on the left side. It may be done.
　図５では，一番初め（一番左側）に，データ量が0.5ＭＢの第１ページ画像31が並べられ，次に，データ量が0.5ＭＢの第３ページ画像33が並べられている。三番目に，データ量が１ＭＢの第２ページ画像32が並べられている。四番目以降のページ画像（図示略）についても第１の圧縮処理後のデータ量の少ない順に並べられている。最後に，データ量が２ＭＢの第10ページ画像40が並べられている。 In FIG. 5, the first page image 31 with a data amount of 0.5 MB is arranged at the very beginning (leftmost), and then the third page image 33 with a data amount of 0.5 MB is arranged. Thirdly, the second page image 32 having a data amount of 1 MB is arranged. The fourth and subsequent page images (not shown) are also arranged in ascending order of data amount after the first compression processing. Finally, the 10th page image 40 having a data amount of 2 MB is arranged.
　ページ画像31～40の並び替えが行われると，式１の演算式にもとづくデータ量（ページ目標データ量）となるように第ｎ（ｎは１以上の整数）番目のページ画像が圧縮される（第２の圧縮処理）（図３ステップ23）。 When the page images 31 to 40 are rearranged, the n-th (n is an integer equal to or greater than 1) -th page image is compressed so that the data amount (page target data amount) based on the arithmetic expression of Equation 1 is obtained. (Second compression process) (Step 23 in FIG. 3).
　［（全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（第１の圧縮処理において得られた漫画画像全体のデータ量）－｛第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝・・・式１ [(Total target data amount) − {total data amount when the second compression processing is performed on the (n−1) th page images}} × (nth obtained in the first compression processing) Data amount of the first page image) / [(data amount of the entire comic image obtained in the first compression process) − {of the (n−1) th page image obtained in the first compression process Total amount of data} ... Equation 1
　図６は，式１にしたがって，第１番目のページ画像31が第２の圧縮処理された様子を示している。 FIG. 6 shows a state in which the first page image 31 is subjected to the second compression processing according to Equation 1.
　全体目標データ量は20ＭＢであり，第１番目のページ画像31は，式１においてｎ＝１であるから，式１において，｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝および｛第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝は，いずれも０となる。したがって，第１番目のページ画像31は，｛（20ＭＢ－０ＭＢ）×（0.5ＭＢ）｝／｛（10ＭＢ）－（０ＭＢ）｝＝１ＭＢとなるようなＱ値が指定されて，第２の圧縮処理が行われる。第２の圧縮処理により，第１の圧縮処理が行われた第１番目のページ画像のデータ量が２倍となる。 Since the total target data amount is 20 MB and the first page image 31 is n = 1 in the equation 1, the second compression processing is performed for the page images up to (n−1) th in the equation 1. The total data amount at the time when the image data is performed} and {the total data amount of the (n−1) th page images obtained in the first compression process} are both 0. Accordingly, the first page image 31 is assigned a Q value such that {(20 MB−0 MB) × (0.5 MB)} / {(10 MB) − (0 MB)} = 1 MB. Processing is performed. By the second compression process, the data amount of the first page image subjected to the first compression process is doubled.
　式１にもとづいて得られるデータ量となるようにＱ値が指定されて第２の圧縮処理が行われた場合，式１にもとづいて得られるデータ量となるかどうかは実際に圧縮してみないと分らない。このために，式１にもとづいて得られるデータ量と一致するデータ量となるような第２の圧縮処理を行うことができることもあるが，できないこともある。このために，式１にもとづいて得られるデータ量と一致するデータ量となるような第２の圧縮処理が行われたかどうかが確認される（ステップ24）。そのような第２の圧縮処理において，式１にもとづいて得られるデータ量と一致するデータ量とならなかった場合には（ステップ24でＮＯ），式１にもとづいて得られるデータ量に所定の割合（たとえば，1.1）を乗じたデータ量近傍のデータ量となるように第ｎ番目のページ画像が圧縮される（ステップ25）。 If the Q value is specified so that the amount of data obtained based on Equation 1 is specified and the second compression processing is performed, whether or not the amount of data obtained based on Equation 1 is actually compressed is tried. I have no idea. For this reason, the second compression process may be performed such that the data amount matches the data amount obtained based on Equation 1, but it may not. For this purpose, it is confirmed whether or not the second compression processing has been performed so that the data amount coincides with the data amount obtained based on Equation 1 (step 24). In such second compression processing, if the data amount does not coincide with the data amount obtained based on Equation 1 (NO in step 24), the data amount obtained based on Equation 1 is set to a predetermined value. The nth page image is compressed so that the data amount is close to the data amount multiplied by the ratio (for example, 1.1) (step 25).
　すべてのページ画像について，ステップ23およびステップ24の処理が行われる（必要に応じてステップ25の処理も）（ステップ26）。すべてのページ画像についてステップ23等の処理が終了していなければ，ｎがインクレメントされ（ステップ27），再びステップ23からの処理が繰り返される。 The processing of step 23 and step 24 is performed for all page images (the processing of step 25 is also performed as necessary) (step 26). If the processing in step 23 and the like has not been completed for all page images, n is incremented (step 27), and the processing from step 23 is repeated again.
　図７は，式１にしたがって，第２番目のページ画像33が第２の圧縮処理された様子を示している。 FIG. 7 shows a state in which the second page image 33 is subjected to the second compression processing according to Equation 1.
　全体目標データ量は20ＭＢであり，第２番目のページ画像33は，式１においてｎ＝２であるから，｛（20ＭＢ－１ＭＢ）×（0.5ＭＢ）｝／｛（10ＭＢ）－（0.5ＭＢ）｝＝１ＭＢとなるようなＱ値が指定されて，第２の圧縮処理が行われる。 Since the total target data amount is 20 MB and the second page image 33 is n = 2 in Equation 1, {(20 MB-1 MB) × (0.5 MB)} / {(10 MB) − (0.5 MB) } = 1 MB is designated, and the second compression process is performed.
　第３番目以降のページ画像についても同様の処理が繰り返される。第２の圧縮処理後のページ画像の画質は比較的均等になる。しかも，第２の圧縮処理後の漫画画像全体のデータ量は目標データ量近傍となる。 The same processing is repeated for the third and subsequent page images. The image quality of the page image after the second compression processing is relatively uniform. Moreover, the data amount of the entire comic image after the second compression processing is close to the target data amount.
　図８は，第１の圧縮処理後に並び換えられたページ画像31～40の一例であり，図５に対応している。 FIG. 8 is an example of page images 31 to 40 rearranged after the first compression processing, and corresponds to FIG.
　上述したように，第１の圧縮処理が行われると，圧縮後のデータ量の少ない順にページ画像31～40が並び換えられる。しかしながら，漫画画像には，見開きの２ページの画像に渡ってコマが形成されていることがある。そのようなコマが形成されている見開きの２ページの画像については連続するように並び替えが規定される。 As described above, when the first compression processing is performed, the page images 31 to 40 are rearranged in ascending order of the amount of data after compression. However, in the comic image, a frame may be formed across the two-page spread image. For two-page spread images on which such frames are formed, rearrangement is defined so as to be continuous.
　図５では，第１の圧縮処理後の第１ページ画像31および第３ページ画像33のいずれもデータ量が0.5ＭＢであり，第１圧縮処理後の第２ページ画像32のデータ量が１ＭＢであったので，データ量の少ない順として，第１ページ画像31，第３ページ画像33，第２ページ画像32と並び替えが行われていたが，図８では，第１ページ画像31と第２ページ画像32とは見開きにわたってコマが形成されているので，第２ページ画像32のデータ量が第３ページ画像33のデータ量よりも少ないにも関わらず，第１ページ画像31と第２ページ画像32とが連続している。 In FIG. 5, the data amount of both the first page image 31 and the third page image 33 after the first compression processing is 0.5 MB, and the data amount of the second page image 32 after the first compression processing is 1 MB. As a result, the first page image 31, the third page image 33, and the second page image 32 are rearranged in order of decreasing data amount. In FIG. Since the frame is formed over the page image 32, the first page image 31 and the second page image are formed even though the data amount of the second page image 32 is smaller than the data amount of the third page image 33. 32 is continuous.
　このように，見開きに渡ってコマが形成されているページ画像が連続するように並び替えが行われて上述した第２の圧縮処理が行われるようにしてもよい。さらに，見開きのページ画像にわたってコマが割り当てられている場合には，これらの見開きのページ画像については同じＱ値（圧縮率）で圧縮するようにしてもよい。見開きページにわたってコマが形成されているか否かを示すデータは，漫画画像を表わすファイルのヘッダ等にあらかじめ記憶されており，そのデータを参照することにより，見開きのページにコマが形成されていることが分るのはいうまでもない。 As described above, the second compression processing described above may be performed by rearranging the page images in which the frames are formed over the spread so as to be continuous. Furthermore, when a frame is allocated over spread page images, these spread page images may be compressed with the same Q value (compression ratio). Data indicating whether or not a frame is formed over the spread page is stored in advance in the header of the file representing the cartoon image, and the frame is formed on the spread page by referring to the data. Needless to say.
　図９から図15は，他の実施例を示している。 9 to 15 show other embodiments.
　この実施例では，ページ画像に含まれるコマごとに上述した圧縮処理が行われる。 In this embodiment, the above-described compression process is performed for each frame included in the page image.
　上述したように（図４参照），漫画画像を構成するすべてのページ画像について初期Ｑ値で第１の圧縮処理が行われる（ステップ51）。 As described above (see FIG. 4), the first compression processing is performed with the initial Q value for all page images constituting the comic image (step 51).
　第１の圧縮処理が行われたすべてのページ画像のそれぞれのページ画像において，ページ画像に含まれるコマごとに，コマの座標，コマの面積，第１の圧縮処理後のコマのデータ量が記憶される（ステップ52）。 In each page image of all page images subjected to the first compression processing, for each frame included in the page image, the frame coordinates, the area of the frame, and the data amount of the frame after the first compression processing are stored. (Step 52).
　図11は，第１の圧縮処理が行われた第１ページ画像31の一例である。 FIG. 11 shows an example of the first page image 31 that has been subjected to the first compression processing.
　第１の圧縮処理が行われた第１ページ画像31のデータ量は，上述のように0.5ＭＢである。 The data amount of the first page image 31 on which the first compression processing has been performed is 0.5 MB as described above.
　第１ページ画像31には，第１のコマ71から第６のコマ76までの６つのコマが含まれている。第１の圧縮処理後の第１のコマ71のデータ量，第２のコマ72のデータ量，第３のコマ73のデータ量，第４のコマ74のデータ量，第５のコマ75のデータ量および第６のコマ76のデータ量は，それぞれ0.5ＭＢ，0.07ＭＢ，0.12ＭＢ，0.02ＭＢ，0.11ＭＢおよび0.08ＭＢであったものとする。 The first page image 31 includes six frames from the first frame 71 to the sixth frame 76. Data amount of first frame 71, data amount of second frame 72, data amount of third frame 73, data amount of fourth frame 74, data of fifth frame 75 after the first compression processing The amount and the data amount of the sixth frame 76 are 0.5 MB, 0.07 MB, 0.12 MB, 0.02 MB, 0.11 MB, and 0.08 MB, respectively.
　図12は，第１ページ画像31についてのコマ・テーブルの一例である。第１ページ画像31以外の漫画画像を構成するページ画像についても同様にコマ・テーブルが形成される。 FIG. 12 is an example of a frame table for the first page image 31. A frame table is similarly formed for the page images constituting the comic image other than the first page image 31.
　コマ・テーブルには，コマ番号，座標，面積，データ量の各欄が形成されている。コマ番号は，ページ画像に含まれるコマを識別するものである。コマ番号１，２，３，４，５および６のそれぞれが，第１のコマ71，第２のコマ72，第３のコマ73，第４のコマ74，第５のコマ75および第６のコマ76に対応している。座標は，ページ画像における各コマの位置を示している。第１ページ画像31を構成するコマ71から76は四角形であるために，それらの四角形の頂点が座標で表わされることにより，コマ71から76の各コマの位置が特定される。たとえば，第１ページ画像31の左上（右上）が原点とされる。面積は，各コマの面積である。データ量は第１圧縮処理が行われた各コマのデータ量である。これらの座標，面積およびデータ量がコマ番号に対応してコマ・テーブルに格納される。コマ・テーブルが漫画画像圧縮装置１のメモリ４に格納されることにより，コマごとに座標等が漫画画像圧縮装置１に記憶されることとなる。 In the frame table, columns of frame number, coordinates, area, and data amount are formed. The frame number identifies a frame included in the page image. Frame numbers 1, 2, 3, 4, 5, and 6 are respectively the first frame 71, the second frame 72, the third frame 73, the fourth frame 74, the fifth frame 75, and the sixth frame. It corresponds to frame 76. The coordinates indicate the position of each frame in the page image. Since the frames 71 to 76 constituting the first page image 31 are quadrangles, the positions of the frames 71 to 76 are specified by representing the vertices of the quadrangles with coordinates. For example, the upper left (upper right) of the first page image 31 is the origin. The area is the area of each frame. The data amount is the data amount of each frame on which the first compression processing has been performed. These coordinates, area, and data amount are stored in the frame table corresponding to the frame number. By storing the frame table in the memory 4 of the comic image compression apparatus 1, the coordinates and the like are stored in the comic image compression apparatus 1 for each frame.
　つづいて，（コマのデータ量／コマの面積）の小さい順に，第１の圧縮処理されたページ画像を構成するコマ画像が並び換えられる（図９ステップ53）。 Subsequently, the frame images constituting the first compressed page image are rearranged in the ascending order of (frame data amount / frame area) (step 53 in FIG. 9).
　図13は，（コマのデータ量／コマの面積）の小さい順に並び換えられたコマ画像の一例である。 FIG. 13 shows an example of the frame images rearranged in ascending order of (frame data amount / frame area).
　図５に示した例では，第１圧縮処理後のページ画像のデータ量の少ない順にページ画像が並び換えられているが，この実施例では，コマ画像は，（コマのデータ量／コマの面積）の小さい順に並び換えられる。これは，単位面積当たりのデータ量が少ないコマについて優先的に第２の圧縮処理が行われるようにするためである。 In the example shown in FIG. 5, the page images are rearranged in the order of the data amount of the page image after the first compression processing. In this embodiment, the frame images are represented by (frame data amount / frame area). ) In ascending order. This is because the second compression process is preferentially performed for frames with a small amount of data per unit area.
　図13においては，（コマのデータ量／コマの面積）の小さい順に，第２のコマ72，第４のコマ74，第６のコマ76，第５のコマ75，第３のコマ73および第１のコマ71が並べられている。 In FIG. 13, the second frame 72, the fourth frame 74, the sixth frame 76, the fifth frame 75, the third frame 73, and the first frame are in order of increasing (data amount of frame / area of frame). One frame 71 is arranged.
　コマ画像71から76の並び換えが行われると，（コマのデータ量／コマの面積）が少ない順に，式２の演算式にもとづくデータ量（コマ画像目標データ量）となるように第ｍ（ｍは１以上の整数）番目のコマ画像が圧縮される（第２の圧縮処理）（図９ステップ54）。 When the frame images 71 to 76 are rearranged, the mth ((frame image target data amount)) becomes the data amount (the frame image target data amount) based on the arithmetic expression of Equation 2 in the order of decreasing (frame data amount / frame area). The m-th frame image is compressed (second compression processing) (step 54 in FIG. 9).
　［（ページ画像目標データ量）－｛第（ｍ－１）番目までのコマ画像について第２の圧縮処理が行われたときのコマ画像の総データ量｝］×（第１の圧縮処理において得られた第ｍ番目のコマ画像のデータ量）／［（第１の圧縮処理において得られたページ画像のデータ量）－｛第１の圧縮処理において得られた第（ｍ－１）番目までのコマ画像の総データ量｝・・・式２ [(Page image target data amount) − {total amount of frame image data when second compression processing is performed for the (m−1) th frame image}] × (obtained in the first compression processing) Data amount of the m-th frame image) / [(data amount of the page image obtained in the first compression processing) − {(m−1) -th obtained in the first compression processing] Total data amount of frame image} ... Equation 2
　図14は，式２にしたがって，第１番目のコマ画像72が第２の圧縮処理された様子を示している。 FIG. 14 shows a state in which the first frame image 72 is subjected to the second compression processing according to Equation 2.
　ページ画像目標データ量は図６から分るように，１ＭＢである。第１番目のコマ画像72は，式２においてｍ＝１であるから，式２において，｛第（ｍ－１）番目までのコマ画像について第２の圧縮処理が行われたときのコマ画像の総データ量｝および第１の圧縮処理において得られた第（ｍ－１）番目までのコマ画像の総データ量｝は，いずれも０となる。したがって，第１番目のコマ画像72は，［（１ＭＢ－０ＭＢ）×（0.07ＭＢ）／（0.5ＭＢ）＝0.14ＭＢとなるようなＱ値が指定されて第２の圧縮処理が行われる。第２の圧縮処理により，第１の圧縮処理が行われた第１番目のコマ画像のデータ量が２倍となる。 The page image target data amount is 1 MB as shown in FIG. Since the first frame image 72 is m = 1 in the equation 2, in the equation 2, {the frame image when the second compression processing is performed on the (m−1) th frame images. The total data amount} and the total data amount of the (m−1) -th frame images obtained in the first compression processing are both 0. Therefore, the first frame image 72 is subjected to the second compression process by specifying a Q value such that [(1 MB−0 MB) × (0.07 MB) / (0.5 MB) = 0.14 MB. By the second compression process, the data amount of the first frame image subjected to the first compression process is doubled.
　式２にもとづいて得られるデータ量となるようにＱ値が指定されて第２の圧縮処理が行われた場合，式１の場合と同様に，式２にもとづいて得られるデータ量となるかどうかは実際に圧縮してみないと分らない。このために，式２にもとづいて得られるデータ量と一致するデータ量となるような第２の圧縮処理を行うことができることもあるが，できないこともある。このために，式２にもとづいて得られるデータ量と一致するデータ量となるような第２の圧縮処理が行われたかどうかが確認される（ステップ55）。そのような第２の圧縮処理において，式２にもとづいて得られるデータ量と一致するデータ量とならなかった場合には（ステップ55でＮＯ），上述したのと同様に，式２にもとづいて得られるデータ量に所定の割合（たとえば，1.1）を乗じたデータ量近傍のデータ量となるように第ｍ番目のコマ画像が圧縮される（ステップ56）。 If the Q value is specified so that the amount of data is obtained based on Equation 2 and the second compression process is performed, is the amount of data obtained based on Equation 2 as in Equation 1? I don't know if I don't actually compress it. For this reason, the second compression process may be performed such that the data amount matches the data amount obtained based on Equation 2, but it may not be possible. For this purpose, it is confirmed whether or not the second compression processing has been performed so that the data amount matches the data amount obtained based on Equation 2 (step 55). In such a second compression process, when the data amount does not coincide with the data amount obtained based on Equation 2 (NO in Step 55), as described above, based on Equation 2. The m-th frame image is compressed so as to obtain a data amount in the vicinity of the data amount obtained by multiplying the obtained data amount by a predetermined ratio (for example, 1.1) (step 56).
　すべてのコマ画像についてステップ54およびステップ55の処理が行われる（必要に応じてステップ56の処理も）（ステップ57）。すべてのコマ画像についてステップ54等の処理が終了していなければｍがインクレメントされ（ステップ58），再びステップ54からの処理が繰り返される。 The processing of step 54 and step 55 is performed for all the frame images (the processing of step 56 is also performed if necessary) (step 57). If the processing in step 54 and the like has not been completed for all the frame images, m is incremented (step 58), and the processing from step 54 is repeated again.
　図15は，式２にしたがって，第２番目のコマ画像74が第２圧縮処理された様子を示している。 FIG. 15 shows a state in which the second frame image 74 is subjected to the second compression processing in accordance with Equation 2.
　ページ画像の目標データ量は１ＭＢであり，第２番目のコマ画像74は，式２においてｍ＝２であるから，｛（１ＭＢ－0.14ＭＢ）×（0.02ＭＢ）｝／｛（0.5ＭＢ）－（0.07ＭＢ）｝＝0.04ＭＢとなるようなＱ値が指定されて，第２の圧縮処理が行われる。 Since the target data amount of the page image is 1 MB and the second frame image 74 is m = 2 in Equation 2, {(1 MB−0.14 MB) × (0.02 MB)} / {(0.5 MB) − A Q value such that (0.07 MB)} = 0.04 MB is designated, and the second compression processing is performed.
　第３番目以降のページ画像についても同様の処理が繰り返される。第２の圧縮処理後のコマ画像の画質は，そのページ画像内で比較的均等となる。 The same processing is repeated for the third and subsequent page images. The image quality of the frame image after the second compression processing is relatively uniform within the page image.
　第ｎ番目のページ画像について上述したコマ画像についての圧縮処理が終了すると，すべてのページ画像について処理が終了したかどうかが確認される（図10ステップ59）。終了していなければ（図10ステップ59でＮＯ），ｎがインクレメントされ（図10ステップ60），次のページ画像について図９ステップ52からの処理が繰り返される。 When the above-described compression processing for the frame image for the nth page image is completed, it is confirmed whether or not the processing has been completed for all page images (step 59 in FIG. 10). If not completed (NO in step 59 in FIG. 10), n is incremented (step 60 in FIG. 10), and the processing from step 52 in FIG. 9 is repeated for the next page image.
　図16は，見開きのページに渡ってコマが形成されている様子を示すページ画像の一例である。 FIG. 16 is an example of a page image showing a frame formed over a spread page.
　図16において，右側が第１ページ画像101であり，左側が第２ページ画像102である。第１ページ画像101には，コマ81から85が形成されており，第２ページ画像102にはコマ91から95が形成されている。さらに，第１ページ画像101と第２ページ画像102とにわたってコマ90が形成されている。 In FIG. 16, the right side is the first page image 101 and the left side is the second page image 102. In the first page image 101, frames 81 to 85 are formed, and in the second page image 102, frames 91 to 95 are formed. Further, a frame 90 is formed across the first page image 101 and the second page image 102.
　このような場合に，コマ90のうち，第１ページ画像101に含まれているコマ部分90Ａと第２ページ画像102に含まれているコマ部分90Ｂとを別々のコマと見なして上述した処理を行うようにしてもよい。また，コマ部分90ＡのＱ値とコマ部分90ＢのＱ値とが同じとなるようにしてもよい。 In such a case, among the frames 90, the frame portion 90A included in the first page image 101 and the frame portion 90B included in the second page image 102 are regarded as separate frames, and the above-described processing is performed. You may make it perform. Further, the Q value of the frame portion 90A and the Q value of the frame portion 90B may be the same.
　さらに，漫画画像を構成するすべてのページ画像をコマ画像ごとに並び換えて，第２の圧縮処理後のデータ量が全体目標データ量となるように，コマ画像ごとに第２の圧縮処理が行われるようにしてもよい。 Further, the second compression processing is performed for each frame image so that all the page images constituting the comic image are rearranged for each frame image, and the data amount after the second compression processing becomes the total target data amount. You may be made to be.
　上述の実施例においては，漫画画像について説明したが，漫画画像だけでなく，複数のページ画像から構成される写真集，フォト・ブック（フォト・アルバム）などの画像群について適用できるのはいうまでもない。 In the above-described embodiments, comic images have been described. Needless to say, the present invention can be applied not only to comic images but also to image groups such as photo books and photo books (photo albums) composed of a plurality of page images. Nor.
１　漫画画像圧縮装置
２　ＣＰＵ
31～40，101，102　ページ画像
71～76，81～85，90～95　コマ画像 1 cartoon image compression device 2 CPU
31-40, 101, 102 page images
71-76, 81-85, 90-95 frames

Claims (8)

  1. 　複数のページ画像から構成される画像群のそれぞれのページ画像を，圧縮後のそれぞれのページ画像があらかじめ定められている最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量があらかじめ定められている全体目標データ量以下となる第２の圧縮率と，の間の初期圧縮率を用いて第１の圧縮処理を行う第１の圧縮手段，および
    　上記第１の圧縮手段によって圧縮された画像群を構成するページ画像の圧縮後のデータ量の少ない順に第２の圧縮処理を行うものであって，第ｎ番目のページ画像についてはページ画像目標データ量が，［（上記全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（上記第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（上記第１の圧縮処理において得られた画像群全体のデータ量）－｛上記第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように第２の圧縮処理を行う第２の圧縮手段，
    　を備えた画像圧縮装置。     Each page image of an image group composed of a plurality of page images is divided into a first compression rate at which each page image after compression has an image quality higher than a predetermined minimum image quality, and A first compression means for performing a first compression process using an initial compression ratio between a second compression ratio at which the data amount is equal to or less than a predetermined overall target data amount, and the first compression The second compression processing is performed in ascending order of the data amount after compression of the page images constituting the image group compressed by the means, and the page image target data amount for the nth page image is [( Total target data amount)-{total data amount when the second compression processing is performed for the (n-1) th page images}] × (nth obtained in the first compression processing) Second page Data amount) / [(data amount of the entire image group obtained in the first compression processing) − {total data of page images up to (n−1) th obtained in the first compression processing] Second compression means for performing the second compression processing so that
    An image compression apparatus comprising:
  2. 　上記第２の圧縮手段は，
    　上記ページ画像目標データ量となるような第２の圧縮処理ができない場合には上記ページ画像の目標データ量を所定割合だけ大きくするものである，
    　請求項１に記載の画像圧縮装置。     The second compression means includes
    When the second compression processing that makes the page image target data amount cannot be performed, the target data amount of the page image is increased by a predetermined ratio.
    The image compression apparatus according to claim 1.
  3. 　上記ページ画像は，複数のコマが割り当てられており，
    　上記第２の圧縮手段は，
    　上記第１の圧縮処理後の（コマのデータ量／コマの面積）が少ない順に，第ｍ番目のコマ画像についてのコマ画像目標データ量が，［（上記ページ画像目標データ量）－｛第（ｍ－１）番目までのコマ画像について第２の圧縮処理が行われたときのコマ画像の総データ量｝］×（上記第１の圧縮処理において得られた第ｍ番目のコマ画像のデータ量）／［（上記第１の圧縮処理において得られたページ画像のデータ量）－｛上記第１の圧縮処理において得られた第（ｍ－１）番目までのコマ画像の総データ量｝となるようにコマごとに第２の圧縮処理を行うものである，
    　請求項１または２に記載の画像圧縮装置。     The above page image is assigned multiple frames,
    The second compression means includes
    In order of decreasing (frame data amount / frame area) after the first compression processing, the frame image target data amount for the m-th frame image is [(the page image target data amount) − {(( m−1) Total data amount of frame image when second compression process is performed for up to frame images}] × (data amount of mth frame image obtained in the first compression process) ) / [(Data amount of page image obtained in the first compression process) − {total data amount of frame images up to (m−1) th obtained in the first compression process}. In this way, the second compression process is performed for each frame.
    The image compression apparatus according to claim 1.
  4. 　上記第２の圧縮手段は，
    　見開きのページ画像にわたってコマが割り当てられていることに応じて，その見開きのページ画像については同じ圧縮率で第２の圧縮処理を行うものである，
    　請求項１から３のうち，いずれか一項に記載の画像圧縮装置。     The second compression means includes
    In accordance with the fact that a frame is allocated over the spread page image, the second compression process is performed at the same compression rate for the spread page image.
    The image compression apparatus according to any one of claims 1 to 3.
  5. 　上記第２の圧縮手段は，
    　連続して第１のページ画像と第２のページ画像とで構成される見開きのページ画像にわたってコマが割り当てられていることに応じて，第１のページ画像に割り当てられている第１のコマ部分と第２のページ画像に割り当てられている第２のコマ部分とを別々のコマと見なして第２の圧縮処理を行うものである，
    　請求項３または４に記載の画像圧縮装置。     The second compression means includes
    The first frame portion allocated to the first page image in response to the frame being allocated over the spread page image composed of the first page image and the second page image in succession. And the second frame portion assigned to the second page image are regarded as separate frames and the second compression process is performed.
    The image compression apparatus according to claim 3 or 4.
  6. 　上記第２の圧縮手段は，
    　連続して第１のページ画像と第２のページ画像とで構成される見開きのページ画像にわたってコマが割り当てられていることに応じて，第１のページ画像に割り当てられている第１のコマ部分の圧縮率と第２のページ画像に割り当てられている第２のコマ部分の圧縮率とが同一の圧縮率となるように第２の圧縮処理を行うものである，
    　請求項３または４に記載の画像圧縮装置。     The second compression means includes
    The first frame portion allocated to the first page image in response to the frame being allocated over the spread page image composed of the first page image and the second page image in succession. The second compression processing is performed so that the compression rate of the second frame image and the compression rate of the second frame portion allocated to the second page image are the same.
    The image compression apparatus according to claim 3 or 4.
  7. 　第１の圧縮手段が，複数のページ画像から構成される画像群のそれぞれのページ画像を，圧縮後のそれぞれのページ画像があらかじめ定められている最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量があらかじめ定められている全体目標データ量以下となる第２の圧縮率と，の間の初期圧縮率を用いて第１の圧縮処理を行い，
    　第２の圧縮手段が，上記第１の圧縮手段によって圧縮された画像群を構成するページ画像の圧縮後のデータ量の少ない順に第２の圧縮処理を行うものであって，第ｎ番目のページ画像についてのページ画像目標データ量が，［（上記全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（上記第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（上記第１の圧縮処理において得られた画像群全体のデータ量）－｛上記第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように第２の圧縮処理を行う，
    　画像圧縮装置の動作制御方法。     A first compression unit configured to convert each page image of an image group composed of a plurality of page images to a first compression rate at which each of the compressed page images has an image quality higher than a predetermined minimum image quality; The first compression processing is performed using an initial compression ratio between the second compression ratio in which the data amount of the compressed image group is equal to or less than a predetermined overall target data amount,
    The second compression means performs the second compression processing in order of decreasing data amount after compression of the page images constituting the image group compressed by the first compression means, and the nth page The page image target data amount for the image is [(total target data amount) − {total data amount when the second compression processing is performed for the (n−1) th page images}] × ( Data amount of nth page image obtained in the first compression process) / [(data amount of entire image group obtained in the first compression process) − {obtained in the first compression process The second compression processing is performed so that the total data amount of the (n−1) th page images is obtained}
    An operation control method for an image compression apparatus.
  8. 　画像圧縮装置のコンピュータを制御するコンピュータが読み取り可能なプログラムであって，
    　複数のページ画像から構成される画像群のそれぞれのページ画像を，圧縮後のそれぞれのページ画像があらかじめ定められている最低画質以上の画質となる第１の圧縮率と，圧縮後の画像群のデータ量があらかじめ定められている全体目標データ量以下となる第２の圧縮率と，の間の初期圧縮率を用いて第１の圧縮処理を行わせ，
    　第１の圧縮処理によって圧縮された画像群を構成するページ画像の圧縮後のデータ量の少ない順に第２の圧縮処理を行わせるものであって，第ｎ番目のページ画像についてのページ画像目標データ量が，［（上記全体目標データ量）－｛第（ｎ－１）番目までのページ画像について第２の圧縮処理が行われたときの総データ量｝］×（上記第１の圧縮処理において得られた第ｎ番目のページ画像のデータ量）／［（上記第１の圧縮処理において得られた画像群全体のデータ量）－｛上記第１の圧縮処理において得られた第（ｎ－１）番目までのページ画像の総データ量｝となるように第２の圧縮処理を行わせるように画像圧縮装置のコンピュータを制御するプログラム。     A computer-readable program for controlling a computer of an image compression apparatus,
    Each page image of an image group composed of a plurality of page images is divided into a first compression rate at which each page image after compression has an image quality higher than a predetermined minimum image quality, and The first compression processing is performed using an initial compression ratio between a second compression ratio at which the data amount is equal to or less than a predetermined overall target data amount,
    Page image target data for the nth page image, wherein the second compression processing is performed in ascending order of the amount of data after compression of the page images constituting the image group compressed by the first compression processing. The amount is [(the total target data amount) − {total data amount when the second compression processing is performed on the (n−1) th) page images} × (in the first compression processing) Data amount of the nth page image obtained) / [(data amount of the entire image group obtained in the first compression process) − {(n−1) obtained in the first compression process) A program for controlling the computer of the image compression apparatus so that the second compression processing is performed so that the total data amount of the first page image}.
PCT/JP2013/070164 2012-08-24 2013-07-25 Image compression device, operation control method therefor, and operation program therefor WO2014030485A1 (en)

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