JP2004328577A - Image output apparatus and thumbnail image output apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To output an image so as to be easily visually recognized without preparing a plurality of image data when indicating a list of images or the like. <P>SOLUTION: An image output apparatus 100 inputs a JPEG2000 image and extracts a specific region that is called ROI preset to such an image to generate a thumbnail image. The ROI can be extracted by acquiring a parameter representing a shift-up quantity recorded in the main header or the tile header of the JPEG2000 image and performing EBCOT decoding only for a bit plane that exceeds the shift-up quantity. A characteristic portion or a significant portion in that image is preset in the extracted ROI, thereby outputting the thumbnail image easy to be visually recognized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for outputting an image or a thumbnail image.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, thumbnail images have been used when displaying a list of images on a computer or the like. For example, Patent Literature 1 discloses a technique in which images are displayed as a list using thumbnail images, and a user selects a desired image from the images to perform printing. Conventionally, such thumbnail images have been generated by reducing the entire image to a predetermined size.
[0003]
[Patent Document 1]
JP 2001-229176 A [Patent Document 2]
JP 2001-8149 A
[Problems to be solved by the invention]
However, when the entire image is reduced, the characteristic portion of the image is also reduced, and in some cases, the thumbnail image is difficult to visually recognize. In order to solve such a problem, a thumbnail image cut out of only the characteristic portion may be separately prepared. However, since a plurality of image files are required, another problem that file management is troublesome arises. Was causing it.
[0005]
The present invention has been made in view of such a problem, and it is an object of the present invention to output an easily viewable image without preparing a plurality of image files when displaying a list of images.
[0006]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve at least a part of the above problems, an image output device according to the present invention is configured as follows. That is,
An input unit for inputting an image file in which data representing an image and a parameter for determining the location of a specific area set in advance in the image are recorded;
An extraction unit that analyzes the location of the specific area using the parameter, and extracts an image in the specific area from the image.
An output unit that outputs the extracted image,
The gist is to provide
[0007]
In the specific region, a characteristic portion or an important portion of the image can be set in advance. Therefore, according to the image output device of the present invention, even in the case of displaying a list of images or the like, by extracting and outputting such a specific area, an image that is easily visible can be output. In addition, since it is not necessary to separately prepare an image file in which a characteristic portion of the image is cut out, it is possible to easily manage the image file.
[0008]
In the above image output device,
The specific area may be set in the image in a data format different from other areas in the image.
[0009]
By doing so, for example, a specific area can be set by giving different codes to data in the specific area and other areas, or by changing the number of digits of the data. Alternatively, the specific area may be set by recording coordinate information specifying the specific area in the image file.
[0010]
In the above image output device,
In the data representing the image, a coefficient obtained by expanding the image based on the spatial frequency or a value obtained by encoding the coefficient may be recorded.
[0011]
Such a coefficient can be obtained by performing, for example, a discrete cosine transform or a discrete wavelet transform on the data representing the image. In addition, various encoding methods such as Huffman encoding, arithmetic encoding, and EBCOT encoding can be applied to the encoding. By performing such frequency expansion and encoding, data representing an image can be effectively compressed.
[0012]
In the image output device having such a configuration,
The coefficients in the specific area may be shifted up by a predetermined number of digits compared to coefficients in other areas.
[0013]
For example, when the coefficient is represented by a binary number, the predetermined number of digits may be the maximum number of bits required to represent a coefficient in an area other than the specific area. By doing so, it is possible to easily distinguish the specific region from other regions. The coefficient can be shifted up by, for example, a max shift method for setting a ROI (Region of Interest) in JPEG2000 which is a compression standard for image files.
[0014]
In such a configuration,
The parameter may include information indicating a shift-up amount of the coefficient. This makes it possible to easily analyze the location of the specific area in the image. As such a parameter, for example, if the image file is based on the JPEG2000 standard, a parameter stored in a recording area called an RGN marker in the file can be used.
[0015]
In order to solve at least a part of the above problems, the present invention can be configured as a thumbnail image output device as described below. That is,
An input unit for inputting an image file,
A thumbnail image generation unit capable of generating a plurality of types of thumbnail images from the image file;
A control unit for switching the type of the thumbnail image at a predetermined timing;
An output unit that outputs the thumbnail image;
Is a thumbnail image output device provided with:
[0016]
With a thumbnail image output device having such a configuration, various types of thumbnail images using one image file, such as a thumbnail image obtained by reducing the entire image or a thumbnail image obtained by extracting only a part of the image, are used. Can be output. The predetermined timing may be, for example, a timing when it is detected that the keyboard or the mouse is operated by the user, or a timing when it is detected that a predetermined time has elapsed from the time when the thumbnail image was output first. .
[0017]
In the thumbnail image output device,
In the image file, data representing an image and a parameter for determining the location of a specific region set in the image in advance are recorded,
The thumbnail image generation unit generates at least one of the plurality of types of thumbnail images by analyzing a location of the specific area using the parameter and extracting an image in the specific area from the image. It may be something.
[0018]
With such a configuration, if a characteristic portion or an important portion of the image is set in advance as the specific region, it is possible to output a thumbnail image that is easily visible.
[0019]
In the present invention, the various aspects described above can be applied by appropriately combining or omitting some of them. Further, the present invention can be applied to, for example, an image output method, a thumbnail image output method, a computer program for outputting an image, and a computer program for outputting a thumbnail image. It can also be configured as a computer program, a computer-readable recording medium on which the computer program is recorded, or the like. In any of the configurations, the above-described embodiments can be appropriately applied. As a computer-readable recording medium, for example, various media such as a flexible disk, a CD-ROM, a DVD-ROM, a magneto-optical disk, an IC card, and a hard disk can be used.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. Schematic configuration of image output device:
B. Overview of JPEG2000:
C. Software configuration of image output device:
D. Thumbnail image display processing:
E. FIG. Details of display processing:
[0021]
A. Schematic configuration of image output device:
FIG. 1 is an explanatory diagram illustrating a schematic configuration of the image output device 100. The image output device 100 inputs an image file (hereinafter, referred to as a “JPEG2000 image”) generated based on JPEG2000 which is a compression standard of image data, and a ROI (Region of Interest) set in advance for the JPEG2000 image. This is a device that generates and outputs a thumbnail image by extracting a specific area called a thumbnail image. The image output device 100 is a so-called personal computer, and is configured by connecting a CPU 10, a ROM 20, a RAM 30, a CRT controller 40, and a hard disk 50 via a predetermined bus 60.
[0022]
A BIOS for initializing hardware and the like is recorded in the ROM 20, and a thumbnail image display program 70 for displaying thumbnail images is installed on the hard disk 50. The CPU 10 executes these programs by using the RAM 30 as a work area. The thumbnail image generated by the thumbnail image display program 70 is output to a monitor via the CRT controller 40.
[0023]
B. Overview of JPEG2000:
JPEG2000 images have various features, such as superior compressibility and image quality, compared to conventional JPEG images. Further, as a function not defined in the conventional JPEG, there is a feature that an ROI can be set. In JPEG2000, an important region or a characteristic region of an image is set in advance as the ROI, and data compression can be performed while prioritizing the image quality in the region over other regions. By using this function, for example, in medical images, it is possible to compress image data while giving priority to the image quality of the affected part. The image output device 100 of the present embodiment generates a thumbnail image using the ROI. Hereinafter, an image encoding process in JPEG2000 will be briefly described as background art for describing a method of handling an ROI in the present embodiment.
[0024]
FIG. 2 is a flowchart showing the encoding processing of a JPEG2000 image. First, the dynamic range of the RGB signal is reduced to half by the DC level shift of the original image to be encoded (step S10). Then, the RGB signals are converted into YCbCr signals by a color conversion process (step S11).
[0025]
Next, the image is divided into a plurality of regions (tiles) (step S12). The following wavelet transform, EBCOT encoding, and the like are performed for each of the divided tiles. However, since such a step is optional, it need not be divided into tiles.
[0026]
Next, a discrete wavelet transform (DWT) is performed for each tile (step S13). In JPEG2000, a two-dimensional DWT is realized by repeatedly using a one-dimensional two-division filter bank based on the concept of a separation type filter bank. FIG. 3 is an explanatory diagram illustrating an execution example of the DWT. Here, it is assumed that there is one tile. FIG. 3A shows an original image before DWT is applied. FIG. 3 (D) shows a result obtained by separating the high-frequency component and the low-frequency component in the horizontal direction and the vertical direction by two filters of a high-frequency filter and a low-frequency filter while down-sampling such an image by DWT, and decomposing the image into a plurality of sub-bands. b). By default, such a DWT is repeated five times for the low frequency portion. FIG. 3C shows the result when DWT is performed three times.
[0027]
Next, the ROI is set (step S14). FIG. 4 is an explanatory diagram illustrating an example of setting the ROI. Here, as shown in FIG. 4A, the case where the center of the original image is set as the ROI has been described. FIGS. 4B and 4C show ROIs in the frequency space corresponding to the ROIs of the original image. The setting of the ROI is realized by shifting up the coefficients in the ROI in such a frequency space. FIG. 5 is an explanatory diagram showing a coefficient shift-up method. As shown in the figure, the setting of the ROI is performed by shifting up the coefficient of the ROI part so as to exceed the maximum number of bits (MSB) required to represent the coefficient of the background part. Such a method is called a max shift method in the JPEG2000 standard. The coefficient in the ROI shifted up in this way is assigned a larger code amount than the background in the subsequent EBCOT encoding process, so that the image quality of the area can be relatively improved. Note that a plurality of ROIs can be set in an image. In addition, the setting of the ROI is optional according to the standard, and may or may not be set.
[0028]
Next, EBCOT (Embedded Block Coding with Optimized Truncation) coding is performed (step S15). In this step, the data compression of the coefficients obtained by the DWT is performed according to procedures of code block division, bit plane decomposition, sub-bit plane decomposition, and arithmetic coding. In the code block division, each sub-band is divided into rectangular areas called code blocks. In EBCOT, the subsequent processing is independently performed for each code block. The size of the code block is 64 × 64 by default. In the bit plane decomposition, coefficients are decomposed into bit planes. FIG. 6 is an explanatory diagram showing an example of the bit plane decomposition. Here, a case is shown in which the coefficients after the upshift shown in FIG. 5 are decomposed. After being decomposed into bit planes, the data is further decomposed and arranged into three coding passes (sub-bit planes) in order from the upper bit plane, and arithmetically coded. For the arithmetic coding, an MQ coder which is also used in JBIG2 which is a standard for a binary image is used.
[0029]
Finally, additional information such as header information is multiplexed to generate a JPEG2000 bit stream (step S16). FIG. 7 is an explanatory diagram showing the file structure of the JPEG2000 image generated in this manner. A JPEG2000 image is roughly composed of a main header and tile data. The tile data includes a tile header and image data. EBCOT-encoded data is recorded in the image data. When an ROI is set in an image, a marker called an RGN marker is recorded in a main header or a tile header. The RGN marker is header information recorded when an ROI is set in the image data, and stores a parameter indicating the shift-up amount exceeding the MSB described above. When the RGN marker is recorded in the main header, the ROI is set in any one of the entire images. When the RGN marker is recorded in the tile header, the ROI is set in the tile. When the RGN marker is recorded in both the main header and the tile header, the RGN marker of the main header is basically applied, but for the tile on which the RGN marker is recorded, the RGN marker is applied with priority. Is done.
[0030]
C. Software configuration of image output device:
FIG. 8 is a functional block diagram of the image output device 100 realized by the CPU 10 executing the thumbnail image display program 70 recorded on the hard disk 50. As illustrated, the image output device 100 includes, as functional blocks, an input unit 200, a header analysis unit 210, an EBCOT decoding unit 220, a ROI extraction unit 230, an inverse wavelet transform unit 240, a size adjustment unit 250, an output unit 260, and a switching unit. A portion 270 is provided.
[0031]
The input unit 200 inputs a JPEG2000 image. The JPEG2000 image can be input from an image generation device such as a digital camera or a scanner, various recording media such as a memory card, a CD-ROM, a flexible disk, a hard disk, or a server connected to a network such as the Internet.
[0032]
The header analysis unit 210 analyzes a main header and a tile header. If an RGN marker is recorded in these headers, a parameter representing the shift-up amount is obtained.
[0033]
The EBCOT decoding unit 220 decodes image data recorded in tile data.
[0034]
ROI extracting section 230 extracts an ROI by controlling EBCOT decoding section 220. Specifically, the ROI is extracted by causing the EBCOT decoding unit 220 to decode only the bit plane exceeding the shift-up amount acquired by the header analysis unit. Of course, the ROI may be extracted by decoding all the bit planes and then extracting only the coefficient represented by the number of bits exceeding the shift-up amount.
[0035]
The inverse wavelet transform unit 240 performs an inverse wavelet transform on the extracted ROI, and reconstructs an image in the ROI. Further, if necessary for the reconstruction, synthesis of divided tiles, color conversion, DC level shift, and the like are also performed.
[0036]
The size adjustment unit 250 adjusts the size of the reconstructed image. For example, if the size of the thumbnail image is uniform 160 × 160, enlargement or reduction is performed to this size. By this size adjustment, a thumbnail image using the ROI is finally generated.
[0037]
The output unit 260 outputs the generated thumbnail image to a monitor. The switching unit 270 switches a thumbnail image to be output in response to a predetermined operation from a user. This is because a plurality of thumbnail images may be generated from one JPEG2000 image.
[0038]
D. Thumbnail image display processing:
FIG. 9 is a flowchart of the thumbnail image display process executed by the CPU 10.
[0039]
First, the CPU 10 inputs a JPEG2000 image (step S100). Then, necessary parameters are initialized (step S110). Specifically, the variable t is set to 0 and r is set to 1, and a thumbnail image storage array R [n] for storing thumbnail images is initialized. An array is used because a plurality of thumbnail images may be generated from one image. The entire input image is stored in the array R [0]. This is for generating a thumbnail image in which the entire image is reduced.
[0040]
After the initialization of the parameters, the CPU 10 acquires the t-th tile Tt from the JPEG2000 image (step S120). Then, the tile header and the main header are analyzed to determine whether there is an RGN marker (step S130). If the RGN marker exists (Step S130: Yes), it is further determined whether or not the upshift amount is 0 (Step S140).
[0041]
If it is determined in step S130 that there is no RGN marker (step 130: No), or if the shift-up amount is determined to be 0 in step 140 (step S140: Yes), the ROI is set for the tile. It has not been done. Therefore, the process proceeds to step S180 described below.
[0042]
If it is determined in step S140 that the shift-up amount is not 0 (step S140: No), the ROI is set to the tile Tt. In such a case, it is further determined whether or not the tile Tt is adjacent to the tile stored in the array R other than R [0] (step S150). If adjacent, the tile Tt is added to the array (step S160). By doing so, even if ROIs are set over a plurality of tiles, they can be stored together in one array R. On the other hand, if there is no adjacent tile (step S150: No), the tile Tt is stored in R [r], and r is incremented (step S170).
[0043]
Next, t is incremented (step S180), and the processing from step S120 to step S180 is repeated until t reaches the total number of tiles recorded in the JPEG2000 image (step S190: No). When the above processing is completed for all the tiles (Step S190: Yes), the ROI is extracted from each tile stored in the array R, and the image in the ROI is reconstructed (Step S200). The reconstructed image is stored again in the array R.
[0044]
Next, size adjustment is performed on all the images stored in the array R (step S210). Through the above processing, a thumbnail image using the ROI is generated.
[0045]
Finally, the CPU 10 displays the thumbnail image on the monitor (Step S220). When a plurality of thumbnail images are generated, the thumbnail images to be displayed can be switched by a user operation. Details of such processing will be described later.
[0046]
FIG. 10 is an explanatory diagram showing the effect of generating a thumbnail image using the ROI. The illustrated image A is an original image. It is assumed that an ROI is set in a portion where a skier exists in such an original image. Image B is a thumbnail image generated by reducing the entire original image. Image C is a thumbnail image generated by extracting the ROI. As shown in the figure, the thumbnail image B generated by reducing the entire image is difficult for a skier who is a feature of the image to visually recognize. on the other hand. In the thumbnail image C, since only skiers are extracted, the features of the image can be immediately visually recognized. Therefore, for example, when a list of images is displayed using thumbnail images, the characteristics of the images can be immediately grasped, and the searchability of the images can be improved.
[0047]
In the thumbnail image display processing described above, an RGN marker is detected from each tile. However, the RGN marker in the tile header may be ignored, and only the RGN marker in the main header may be detected. This makes it possible to easily generate a thumbnail image.
[0048]
E. FIG. Details of display processing:
Here, the display processing in step S220 in FIG. 9 will be described using FIG. 11 and FIG. FIG. 11 is a flowchart of the display process. First, the CPU 10 initializes necessary parameters (step S400). Specifically, the variable r is set to 1. Next, the thumbnail images stored in the thumbnail image storage array R [r] are displayed (step S410). The upper right image in FIG. 12 is an example of the thumbnail image displayed by such processing. The reason that r = 0 was not set in step S400 is that a thumbnail image generated by reducing the entire image is stored in R [0], and the thumbnail image generated by ROI extraction is preferentially displayed. is there.
[0049]
Next, it is determined whether the mouse is single-clicked on the displayed thumbnail image (step S420). If a single click is made (step S420: Yes), r is incremented (step S430), and the process returns to step S410. However, if r has reached the maximum value, r = 0. In this way, as shown in the lower part of FIG. 12, the thumbnail images can be switched and displayed. If a single click has not been made (step S420: No), it is next determined whether or not a double click has been made on the thumbnail image. If double-clicked (step S440: Yes), the original image is displayed on the monitor (step S450), and the process ends. If not double-clicked (Step S440: No), the process returns to Step S420, and the mouse click is detected again.
[0050]
By performing the display processing described above, the thumbnail images stored in the thumbnail image storage array R can be switched and displayed one after another. Therefore, the user can confirm various characteristics of the original image by the thumbnail image without displaying the original image. In the above process, when the mouse is clicked, the thumbnail images are switched and displayed. However, the thumbnail images may be switched and displayed at predetermined time intervals.
[0051]
Although various embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various configurations can be adopted without departing from the gist of the present invention. For example, a function realized by software may be realized by hardware. In the embodiment, the image output apparatus of the present invention is configured by a personal computer. However, the present invention is not limited to this. For example, a digital camera, a television, a VCR, a hard disk recorder, a DVD recorder, or the like can output a thumbnail image. It can be configured using various possible devices. The input image file is not limited to the JPEG2000 format. The specific area may be set by recording coordinate information specifying the specific area in the header of the image file. In such a case, the coordinate information may be analyzed to extract the specified specific area.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of an image output apparatus 100.
FIG. 2 is a flowchart illustrating encoding processing of a JPEG2000 image.
FIG. 3 is an explanatory diagram illustrating an execution example of a DWT.
FIG. 4 is an explanatory diagram showing an example of setting an ROI.
FIG. 5 is an explanatory view showing a coefficient shift-up method.
FIG. 6 is an explanatory diagram showing an example of bit plane decomposition.
FIG. 7 is an explanatory diagram showing a file structure of a JPEG2000 image.
FIG. 8 is a functional block diagram of the image output apparatus 100.
FIG. 9 is a flowchart of a thumbnail image display process.
FIG. 10 is an explanatory diagram showing an effect of generating a thumbnail image using an ROI.
FIG. 11 is a flowchart of a display process.
FIG. 12 is an explanatory diagram showing a display example of a thumbnail image.
[Explanation of symbols]
10 CPU
20 ... ROM
30 ... RAM
40 CRT controller 50 Hard disk 60 Bus 70 Thumbnail image display program 100 Image output device 200 Input unit 210 Header analysis unit 220 EBCOT decoding unit 230 ROI extraction unit 240 Inverse wavelet transform unit 250 Size adjustment Unit 260 ... Output unit 270 ... Switching unit

Claims (12)

An image output device,
An input unit for inputting an image file in which data representing an image and a parameter for determining the location of a specific area set in advance in the image are recorded;
An extraction unit that analyzes the location of the specific area using the parameter, and extracts an image in the specific area from the image.
An output unit that outputs the extracted image,
An image output device comprising: The image output device according to claim 1,
The image output device, wherein the specific area is set in the image in a data format different from other areas in the image. The image output device according to claim 1,
An image output device, wherein data representing the image includes a coefficient obtained by expanding the image based on a spatial frequency or a value obtained by encoding the coefficient. The image output device according to claim 3,
The image output device, wherein the coefficient in the specific area is shifted up by a predetermined number of digits compared to the coefficient in another area. The image output device according to claim 4,
The image output device, wherein the parameter includes information indicating a shift-up amount of the coefficient. A thumbnail image output device,
An input unit for inputting an image file,
A thumbnail image generation unit capable of generating a plurality of types of thumbnail images from the image file;
A control unit for switching the type of the thumbnail image at a predetermined timing;
An output unit that outputs the thumbnail image;
A thumbnail image output device comprising: The thumbnail image output device according to claim 6, wherein
In the image file, data representing an image and a parameter for determining the location of a specific region set in the image in advance are recorded,
The thumbnail image generation unit generates at least one of the plurality of types of thumbnail images by analyzing a location of the specific area using the parameter and extracting an image in the specific area from the image. , Thumbnail image output device. An output method in which a computer outputs an image,
Inputting an image file in which data representing an image and a parameter for determining the location of a specific region set in advance in the image are recorded;
Analyzing the location of the specific area using the parameter, extracting an image in the specific area from the image,
Outputting the extracted image;
Output method including. An output method in which a computer outputs a thumbnail image,
Inputting an image file;
Generating a thumbnail image from the image file;
Switching the type of the thumbnail image at a predetermined timing;
Outputting the thumbnail image;
Output method including. A computer program for outputting an image, a function of inputting an image file in which data representing the image and a parameter for determining the location of a specific region set in the image in advance, and
A function of analyzing the location of the specific area using the parameter, and extracting an image in the specific area from the image,
A function of outputting the extracted image,
Computer program to make a computer realize. A computer program for outputting a thumbnail image,
A function to input image files,
A function capable of generating a plurality of types of thumbnail images from the image file;
A function of switching the type of the thumbnail image at a predetermined timing,
A function of outputting the thumbnail image;
Computer program to make a computer realize. A computer-readable recording medium on which the computer program according to claim 10 is recorded.

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