JP5947385B2 - Image compression apparatus, operation control method thereof, and operation control program thereof - Google Patents

Description

  The present invention relates to an image compression apparatus, an operation control method thereof, and an operation control program thereof.

  By sending electronic 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.

  Further, even in a situation where the compression rate can be changed according to the shooting conditions, it is possible to ensure an accurate prediction of the number of shots that can be taken (Patent Document 1). There are those that enable storage (Patent Document 2), and those that improve data transfer efficiency by switching the compression method as appropriate (Patent Document 3).

Japanese Patent Laid-Open No. 2008-160770 JP-A-5-64011 Japanese Patent Laid-Open No. 6-292024

  When compressing a digitized image group so as to have a desired data amount, it is preferable that the compression is completed as soon as possible.

  An object of the present invention is to finish compression of image groups such as image groups, imaged photo books, and imaged photo books (photo albums) as soon as possible.

  According to a first aspect of the present invention, there is provided an image compression apparatus comprising: a reading unit that sequentially reads each page image of an image group including a plurality of page images for each page image; and a page of an nth page image read by the reading unit. The target data amount is [(total target data amount of the image group after compression) − {total data amount of the page image after compression up to the (n−1) th}} − (room data amount)] / {(image It is characterized by comprising compression means for compressing so that the total number of pages in the group)-{number of pages up to (n-1) th}.

  The first invention also provides an operation control method suitable for an image compression apparatus. That is, in this method, the reading unit reads each page image of an image group composed of a plurality of page images in order for each page image, and the compression unit reads the nth page image read by the reading unit. The page target data amount is [(total target data amount of the image group after compression) − {total data amount of the page image after compression up to the (n−1) th}} − (room data amount)] / {( The compression is performed so that the total number of pages in the image group)-{number of pages up to (n-1) th}.

  The first invention also provides a computer-readable program for executing the operation control method of the image compression apparatus. A recording medium storing such a program and detachable from the computer may be provided.

  According to the first invention, the image group includes a plurality of page images, and each page image is read sequentially. The data amount (page target data amount) of the read n-th page image is [(total target data amount of the image group after compression) − {(n−1) -th compressed page image of Total data amount} − (room data amount)] / {(total number of pages in image group) − {number of pages up to (n−1) th}}. By compressing the read page images in order, the data amount of the compressed image group becomes a desired data amount (total target data amount), so that the image group can be compressed relatively quickly.

  In the determining means for determining whether or not the total data amount of the page image compressed by the compressing means exceeds the total target data amount, and in the determining means, the total data amount of the page image compressed by the compressing means determines the total target data amount. In response to the determination that it has exceeded the page image compression order in the reverse order of the page image compression, the page image before compression by the compression means is compressed until the image group after compression by the compression means falls within the overall target data amount. You may further provide the compression control means which controls a compression means so that a page image may be compressed.

  It is preferable that the margin data amount decreases as n increases.

  According to a second aspect of the present invention, there is provided reading means, and reading means for sequentially reading the images in the frames for each frame from an image group in which a plurality of such page images are collected. The frame target data amount of the image in the m-th frame read by “[(total target data amount of the compressed image group−total number of images in the compressed frame up to the (m−1) th) frame” Data amount) −allowance data amount] × mth frame area / [(total area of all frames in the image group) − {total area of all (m−1) th frames}]. A compression means for compressing is provided.

  The second invention also provides an operation control method suitable for the image compression apparatus. That is, in this method, the reading means reads the images in the frames one by one from the image group in which the frames are allocated in the page images, and is composed of a plurality of such page images. Means that the frame target data amount of the image in the m-th frame read by the reading unit is [(total target data amount of the compressed image group− (m−1) -th compressed frame). The total data amount of the images in the image) −the marginal data amount] × the area of the mth frame / [(the total area of all the frames in the image group) − {the total area of all the (m−1) th frames}. ] To be compressed.

  Also in the second invention, there is provided a computer-readable program proposed for carrying out the operation control method of the image compression apparatus. A program that stores such a program and is detachable from the computer may be provided.

  According to the second invention, a frame is allocated to a page image, and a plurality of such page images are collected and images in the frame are sequentially read from the image group for each frame. The data amount of the image in the read m-th frame (frame target data amount) is [(total target data amount of image group after compression− (m−1) -th compressed frame in the compressed frame)]. (Total data amount of image) −allowance data amount] × m-th frame area / [(total area of all frames of image group) − {total area of all (m−1) -th frames}] Compressed to be By compressing the images in the read frames in order, the data amount of the compressed image group becomes a desired data amount (total target data amount), so that the image group can be compressed relatively quickly.

  The determining means for determining whether or not the total data amount of the image in the frame compressed by the compression means exceeds the overall target data amount, and in the determining means, the total data amount of the image in the frame compressed by the compression means is In response to the determination that the overall target data amount has been exceeded, the images in the frames have the minimum image quality in the reverse order of the compression order of the images in the frames, and the image group after compression by the compression means is the overall target data. You may further provide the compression control means which controls a compression means so that the image in the frame before the compression by a compression means may be compressed until it fits in quantity.

  The margin data amount is preferably smaller as m is larger.

It is a block diagram which shows the electric constitution of an image group compression apparatus. It is an example of the page image which comprises an image group. It is a flowchart which shows the process sequence of an image group. It is an example of the page image which comprises an image group. It is an example of a page image to which frames are allocated. It is an example of a frame image. It is a flowchart which shows the process sequence of an image group.

  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 a comic image (image group), and an input device 6 such as a keyboard. ing. 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.

  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. 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.

  It is assumed 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 comic image is compressed as quickly as possible so that the total data amount of the comic image becomes 20 MB, which is the target data amount (total target data amount).

  FIG. 3 is a flowchart showing the processing procedure of the comic image compression apparatus 1.

  In this embodiment, JPEG (Joint Photographic Experts Group) is used for compression of the comic image. 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.

  Data representing a cartoon image is stored in the hard disk 8 described above. The parameter n is set to 1 (step 51), and the nth page image is read from the hard disk 8 (step 52). Accordingly, initially, image data representing the page image 31 of the first page is read from the hard disk 8.

  In this embodiment, a Q value is calculated such that the data amount (page target data amount) is based on the arithmetic expression of Equation 1 (step 53). Since a method for calculating the Q value at which the compressed data amount is close to the desired data amount is known, the description thereof is omitted.

  [(Total target data amount of the comic image after compression) − {Total data amount of the page image after compression up to the (n−1) th}} − (Margin data amount)] / {(Total number of pages of the comic image) )-{Number of pages up to the (n-1) th}} Equation 1

  In Equation 1, the surplus data amount is intended to be within the overall target data amount of the compressed comic image when the comic image is compressed, and is, for example, 1 MB. The margin data amount may be reduced as the remaining page images of the compressed comic image are reduced. For example, the margin data amount = (first predetermined value−second predetermined value × n) may be set. However, the first predetermined value> (second predetermined value × n).

  In Equation 1, since the total target data amount is 20 MB and the first page image 31 is n = 1, {total data amount of page images after compression up to the (n−1) th} {Number of pages up to (n-1) th} is 0 in all cases. The data amount of the target page image data of the first page image 31 is (20MB-0MB-1MB) / (10-0) = 1.9 MB. For the first page image 31, 1.9 MB is the data amount of the target page image data, and a Q value is calculated so as to achieve such a data amount, and compression is performed (step 54).

  If a Q value that is the amount of data obtained based on Equation 1 is calculated and compression is performed using the Q value, whether or not the data amount of the target page image data obtained based on Equation 1 is obtained. You won't know unless you actually compress it. For example, the first page image 31 may become 3 MB when actually compressed even though the data amount of the target page image data is 1.9 MB. As described above, the data amount of the target page image data may not match the actual data amount of the page image data after compression.

  FIG. 4 shows a state after the comic image is compressed.

  As described above, it is assumed that the data amount obtained by actual compression is 3 MB even though the data amount of the target page image data of the first page image 31 is 1.9 MB. Similarly, it is assumed that the data amount actually obtained by compression is 2.5 MB even though the data amount of the target page image data of the second page image 32 is 1.77 MB. In this way, if the data amount of the target page image data differs from the data amount actually obtained by compression, the data amount of the target page image data of all the page images constituting the comic image is determined in advance. I can't leave it. In this embodiment, the target page image data amount of page images sequentially read from the hard disk 8 is determined in order according to the above-described equation 1, so that the data amount of the target page image data and the data actually obtained by compression are obtained. Even if the amount is different, the data amount of the comic image after compression can be accommodated in the total target data amount.

  Even if the data amount of the target page image data is determined according to Equation 1 and the page image is compressed so as to be the data amount, the data amount of the compressed comic image does not fit in the total target data amount. (In particular, when the last page image 40 is compressed, the actual amount of data after compression is larger than the target page image data). For this reason, it is confirmed whether or not the total data amount of the page image data after compression exceeds the total target data amount (step 55 in FIG. 3).

  If not exceeded (NO in step 55), it is confirmed whether or not the compression processing has been completed for all page images constituting the comic image (step 59). If not completed, the parameter n is incremented (step 60), and data representing the next page image is read from the hard disk 8 (step 52).

  Even if the data amount of the target page image of the first page image 31 is 1.9 MB, when the data is actually compressed to 3 MB, the data amount of the target page image of the second page image 32 is From Equation 1, (20MB-3M-1MB) / (10-1) = 1.77 MB. A Q value that is the data amount of the target page image is calculated, and the second page image 32 is compressed using the calculated Q value (step 54). If the second page image 32 is actually compressed and the obtained data is, for example, 2.5 MB, the third page image 33, which is the next page image, is obtained according to Equation 1 using the actually obtained data. A target page image data amount is calculated.

  If the compression of the page image is repeated and the total data amount after compression exceeds the total target data amount (YES in step 55), the page image of the nth page before compression is set to a predetermined minimum Q. The value is used for compression (step 56). The minimum Q value is a value such that the compressed image has a minimum image quality. Of course, it may not be the lowest Q value itself, but a value in the vicinity thereof. By compressing using the lowest Q value, the data amount of the page image after compression is reduced, so that the total data amount of the comic image after compression falls within the overall target data amount. If the total data amount after compression does not fall within the overall target data amount (YES in step 57), the parameter n is decremented (step 58), and the page image of the previous page is also compressed using the minimum Q value. Become so. When the total data amount after compression falls within the total target data amount (NO in step 57), the process proceeds to step 59.

  As described above, when the total data amount of the compressed page image exceeds the overall target data amount, the compression before the compression is performed so that the image quality becomes equal to or higher than the minimum image quality in the reverse order of the page image until the total target data amount is reached. The page image may be compressed.

  5 to 7 show other embodiments.

  In the above-described embodiment, the compression process is performed in units of page images. In this embodiment, the compression process is performed in units of images within a frame.

  FIG. 5 shows page images 31, 32 and 40 constituting a comic image. In FIG. 5, page images 31, 32, and 40 are shown, but it goes without saying that there are other page images.

  A first frame 101 to a sixth frame 106 are allocated to the first page image 31. Similarly, the first page 107 to the sixth frame 112 are also assigned to the second page image 32. The total number of frames allocated to the first page image 31 and the second page image 32 is 12. Frames are also allocated to other page images, and the first frame 155 to the seventh frame 161 are allocated to the tenth page image 40 as well. 161 frames are allocated to the entire comic image composed of 10 page images 31-40.

  FIG. 6 shows the frame images shown in FIG. 5 arranged in the order of frame numbers.

  In this embodiment, frame images are read from the hard disk 8 in the order of frame numbers and compressed. However, it goes without saying that reading and compression are not performed in the order of frame numbers.

  FIG. 7 is a flowchart showing the processing procedure of the comic image compression apparatus, and corresponds to FIG. In FIG. 7, the same processes as those shown in FIG.

  Assume that the hard disk 8 stores data representing page images constituting a comic image in frame units. Therefore, data representing the image in the frame can be read from the hard disk 8 in units of frames.

  First, the parameter m is set to 1 (step 51A), and data representing an image (frame image) in the m-th frame is read from the hard disk 8 (step 52A). Therefore, data representing an image in the first frame 101 is initially read from the hard disk 8.

  When data representing an image in units of frames is read from the hard disk 8, a Q value is calculated so as to be a data amount (frame target data amount) based on the equation (2) (step 53A).

  [(Total target data amount of the comic image after compression−Total amount of data in the image after compression up to the (m−1) th) −Amount of surplus data] × Area of the mth frame / [(Manga Total area of all frames in image) − {total area of all (m−1) th frames}] Equation 2

  Similarly to the margin data amount of Equation 1, the margin data amount of Equation 2 is set to be within the overall target data amount of the compressed comic image, and as the number of frames remaining in the compressed cartoon image decreases. , May be reduced. For example, as described above, the margin data amount = (first predetermined value−second predetermined value × m). However, the first predetermined value> (second predetermined value × m). Needless to say, the area of the frame is stored in advance in the header of a file storing comic image data corresponding to the frame number indicating the frame number.

  Using the calculated Q value, the read frame image is compressed (step 54). Similarly to the case of compressing for each image in a frame, a Q value that is the amount of data obtained based on Equation 2 is calculated and compressed using the Q value. In this case, whether or not the data amount of the target frame image data obtained based on Equation 2 is actually compressed cannot be known. For this reason, the data amount of the target frame image data may not coincide with the data amount of the image data representing the image in the actually compressed frame. In this embodiment, the image data in the frames sequentially read from the hard disk is sequentially determined according to the above-described equation 2, so that the data amount of the frame images is different from the data amount actually obtained by compression. However, the data volume of the compressed comic image can be kept within the total target data volume.

  Similarly to the above-described embodiment, even if the data amount of the target frame image data is determined according to Equation 2 and the frame image is compressed so as to be the data amount, The amount of data may not fit within the overall target data amount (particularly, when the last frame image 161 is compressed, the actual amount of data after compression becomes larger than the target frame image data). Therefore, it is confirmed whether or not the total amount of frame image data after compression has exceeded the total target data amount (step 55).

  If not exceeded (NO in step 55), it is confirmed whether or not the compression processing has been completed for all the frame images constituting the comic image (step 59A). If not completed, the parameter m is incremented (step 60A), and data representing the next frame image is read from the hard disk 8 (step 52A).

  If the compression of the frame image is repeated and the total data amount after compression exceeds the total target data amount (YES in step 55), the frame image of the m-th frame before compression is set to a predetermined minimum Q. The value is used for compression (step 56A). The minimum Q value is a value such that the compressed image has a minimum image quality. Of course, it may not be the lowest Q value itself, but a value in the vicinity thereof. By compressing using the minimum Q value, the data amount of the frame image after compression is reduced, so that the total data amount of the comic image after compression falls within the overall target data amount. If the total data amount after compression does not fall within the overall target data amount (YES in step 57), the parameter m is decremented (step 58A), and the frame image of the previous frame is also compressed using the minimum Q value. Become so. When the total data amount after compression falls within the total target data amount (NO in step 57), the process proceeds to step 59.

  In this way, when the total data amount of the compressed frame image exceeds the overall target data amount, the compression is performed so that the image quality becomes equal to or higher than the minimum image quality in the reverse order of the compression order of the frame image until the total target data amount is reached. The frame image may be compressed.

  In the above-described embodiment, the frame images are compressed in the order of the frame numbers. However, frames that are spread over two pages may be regarded as separate frames and the above-described processing may be performed. The above-described processing may be performed by considering it as one frame.

  In the above-described embodiment, the compression of the comic image has been described. Needless to say, the present invention can also be applied to an image collection other than the comic image, a photo book (photo album), and the like.

1 cartoon image compression device 2 CPU
31-40 page image
101-161 frame images

Claims (10)

Reading means for sequentially reading each page image of an image group composed of a plurality of page images for each page image, and the page target data amount of the nth page image read by the reading means is [(after compression The total target data amount of the image group) − {the total data amount of the page images after compression up to the (n−1) th}} − (the margin data amount)] / {(the total number of pages of the image group) − {the first. Compression means for compressing so that the number of pages up to (n-1) th}
An image compression apparatus comprising: Determining means for determining whether or not the total data amount of the page image compressed by the compression means exceeds the overall target data amount; and in the determining means, the total data amount of the page image compressed by the compression means is When it is determined that the overall target data amount has been exceeded, until the page image exceeds the minimum image quality in the reverse order of the compression order of the page image, and the group of images compressed by the compression means falls within the overall target data amount , Compression control means for controlling the compression means so as to compress the page image before compression by the compression means,
The image compression apparatus according to claim 1, further comprising:   The image compression apparatus according to claim 1, wherein the margin data amount decreases as n increases. A reading means for sequentially reading the images in the frame for each frame from an image group composed of a plurality of such page images in which the frames are allocated in the page image, and the reading means read by the reading means. The frame target data amount of the image in the mth frame is [(total target data amount of the image group after compression−total data amount of images in the frame after compression up to the (m−1) th) − margin Compression means for compressing so that the amount of data] × m-th frame area / [(total area of all frames in image group) − {total area of all (m−1) -th frames}];
An image compression apparatus comprising: Determination means for determining whether the total data amount of the images in the frame compressed by the compression means exceeds the overall target data amount; and in the determination means, the image data in the frames compressed by the compression means When it is determined that the total data amount exceeds the overall target data amount, the images in the frames are in the reverse order of the compression order of the images in the frames, and the images in the frames are equal to or higher than the minimum image quality, and after compression by the compression means. Compression control means for controlling the compression means so as to compress the image in the frame before compression by the compression means until the image group falls within the overall target data amount;
The image compression apparatus according to claim 4, further comprising:   The image compression apparatus according to claim 4 or 5, wherein the margin data amount decreases as m increases. The reading means reads each page image of an image group composed of a plurality of page images in order for each page image,
The compression means is such that the page target data amount of the nth page image read by the reading means is [(total target data amount of the image group after compression) − {after compression to the (n−1) th compression]. The total amount of data of page images} − (room data amount)] / {(total number of pages in image group) − {number of pages up to (n−1) th}}
An operation control method for an image compression apparatus. The reading means reads the images in the frame one by one from the group of images in which a plurality of such page images are arranged, in which the frames are allocated in the page image,
The compression means determines that the frame target data amount of the image in the m-th frame read by the reading means is [(compressed total target data amount of image group after compression to the (m−1) th compression). (Total data amount of image in frame)-margin data amount] x area of mth frame / [(total area of all frames of image group)-{total of all (m-1) th frames Area}],
An operation control method for an image compression apparatus. A computer-readable program for controlling a computer of an image compression device, wherein each page image of an image group composed of a plurality of page images is read in order for each page image,
The page target data amount of the read nth page image is [(total target data amount of the image group after compression) − {total data amount of the page image after compression up to the (n−1) th}}. A program for controlling the computer of the image compression apparatus so that compression is performed so as to satisfy − (allowance data amount)] / {(total number of pages in the image group) − {number of pages up to the (n−1) th page}. A computer-readable program for controlling a computer of an image compression apparatus,
From the image group composed of a collection of such page images in which frames are allocated in the page image, the images in the frame are read in order for each frame,
The frame target data amount of the image in the read m-th frame is [(total target data amount of image group after compression−total data of images in the frame after compression up to the (m−1) th frame). Amount) −allowance data amount] × m-th frame area / [(total area of all frames in the image group) − {total area of all (m−1) -th frames}]. A program for controlling the computer of the image compression apparatus.

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