JP2004120169A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the storage capacity required for storing respective image data in an electronic apparatus for storing compressed image data. <P>SOLUTION: A mobile phone (1) for compressing image data in compliance with the JPEG (joint picture expert group) system is provided with a memory (22) for storing a Huffman table used for a coding stage, and by using the Huffman table stored in the memory (22), encodes the image data and excludes the Huffman table from parameters stored together with the image data. In the case of decompression being reverse processing of the compression, the mobile phone uses the Huffman table stored in the memory (22) to decode the image data. The mobile phone generates image data of thumbnail pictures reducing pictures from the image data and applies the processing above to the image data of the thumbnail pictures. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device having a function of handling an image.
[0002]
[Prior art]
Portable telephones that connect to the Internet through telephone functions are becoming widespread. In such a portable telephone, like a personal computer, information can be downloaded via the Internet, or a file can be attached to an e-mail and sent / received. Many portable telephones have a relatively large display device and can display an image, and can display an image represented by downloaded image data or image data attached to a received mail. A mobile phone is also provided with a camera, and it is also possible to display a photographed image or to attach the image data to an e-mail and transmit it.
[0003]
In recent years, image data representing left and right images with parallax has been provided via the Internet, and a portable telephone that displays not only a two-dimensional two-dimensional image but also a three-dimensional three-dimensional image has been proposed. (For example, JP-A-2001-251403). In such a mobile phone, the setting of the display device can be switched between displaying a two-dimensional image and displaying a three-dimensional image.
[0004]
Further, a technology for generating three-dimensional image data representing a three-dimensional image from two-dimensional image data representing an image captured by a camera has been developed (for example, Japanese Patent Application Laid-Open No. 2000-228778). It is preferable that the mobile phone is small and lightweight. Therefore, it is not practical to use two cameras to capture images for the left eye and the right eye. Is suitable for a mobile phone.
[0005]
The image data is treated as a file, and the file is given a file name including a name for identifying the image and an extension indicating the type of the image, that is, the format of the image data. Since the image data has a large amount of data, it is usually compressed, and decompression, which is a reverse process of compression, is performed at the time of display to return to a form suitable for display. The compression is generally performed according to the JPEG system, and the extension of the file name of the image data in this case is “JPEG” or “JPG”. In the file, the size (the number of pixels) of the image is described together with the image data. Further, information on copyright such as the name of the author is added to the file of the image data provided via the Internet.
[0006]
When displaying an image or attaching image data to an e-mail, the user can list image file names and select image data. However, simply displaying the file name is inconvenient because it is difficult to understand the contents of the image represented by the image data. Therefore, image data representing an image obtained by reducing an original image is created from each image data, and the images are displayed side by side. Such a reduced image is called a thumbnail image. The image data of the thumbnail image is created by extracting pixel data separated from the original image data, that is, by thinning out the image data. By displaying the thumbnail images side by side, the contents of the images represented by many pieces of image data can be immediately understood, and the selection by the user becomes extremely easy.
[0007]
[Patent Document] Japanese Patent Application Laid-Open No. 2001-251403 [Patent Document] Japanese Patent Application Laid-Open No. 2000-228778
[Problems to be solved by the invention]
As described above, generally, image data is compressed in accordance with the JPEG system and stored in a compressed state. JPEG compression includes an encoding stage and a subsequent quantization stage. In encoding, a parameter called a Huffman table is used, and in quantization, a parameter called a quantization table is used. At the time of decompression, it is necessary to perform reverse processing of quantization and reverse processing (decoding) of encoding. Therefore, parameters including the Huffman table and the quantization table are stored together with the compressed image data. In many cases, the image data of the thumbnail image is compressed and stored in accordance with the JPEG method. In this case, all the parameters including the Huffman table are stored for the image data of the thumbnail image.
[0009]
However, since the Huffman table is large, storing the Huffman table together with the individual image data requires a large storage area and reduces the number of image data that can be stored. Particularly, the image data of the thumbnail image is useful in that the thumbnail image can be promptly displayed by storing the image data, but is not indispensable because it can be created from the original image data as needed. Storing the Huffman table for the image data of the thumbnail images does not desirably reduce the number of storable image data.
[0010]
The present invention has been made in view of such problems, and has been made to reduce a storage capacity required for storing individual image data in an electronic device such as a mobile phone that compresses and stores image data. Aim.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in an electronic device that compresses image data representing an image and stores the compressed image data together with parameters used for compression, a parameter independent of image data among parameters used for compression Is provided, at least a part of the compression of the image data is performed using the parameters stored in the memory, and the parameters stored in the memory are excluded from the parameters stored together with the image data. I do.
[0012]
In this electronic device, among parameters used for image data compression, parameters that do not depend on image data are not separately prepared for each image data, but predetermined parameters are stored in a memory and commonly used. . By excluding this parameter from the parameters stored together with the image data, the storage capacity can be saved and a large amount of image data can be stored.
[0013]
In the above electronic device, the image data is compressed according to the JPEG method, and a Huffman table used in the encoding step is stored in a memory. Since the Huffman table is large and requires a large amount of storage capacity, by excluding the Huffman table from the parameters stored together with the image data, the storage capacity can be greatly reduced.
[0014]
When reproducing the image data before compression by the inverse processing of the compression, the parameters stored in the memory are used. For example, when the Huffman table is excluded from the parameters stored together with the image data, decoding is performed using the Huffman table stored in the memory.
[0015]
The image data to be compressed may be created by extracting from image data representing an image larger than the image represented by the image data, that is, a thumbnail image. Since the thumbnail images are used only by the telephone and not provided, no inconvenience occurs even if the parameters in the memory are commonly used for the image data of all the thumbnail images. If a certain parameter is used irrespective of the image data, the compression efficiency may decrease and the storage capacity required for storing the compressed image data may increase somewhat, but the number of parameters to be stored is reduced. In many cases, the effect of saving the storage capacity is greater. For example, if the Huffman table is not stored together with the image data of the thumbnail image, the storage capacity can be reduced by nearly 50%.
[0016]
It is useful to encode image data of an image other than the thumbnail image using the parameters in the memory and to exclude the parameters from the parameters stored together with the image data. For example, a camera that captures an image may be provided, and the image data to be compressed may represent an image captured by the camera. It is convenient for a user who wants to use the captured images by himself / herself because many images can be captured and stored.
[0017]
In addition, when the image data obtained via the Internet is modified for individual use by the user, for example, when decoration is added or converted so as to represent a three-dimensional image, the image after the modification is modified. It is also useful when saving data. Such image data should not be provided elsewhere in view of the copyright of the original image data, but even if it is attached by mistake to email, it is difficult to decompress because some parameters are missing, Copyright can be protected. The portrait right is also protected for image data representing an image of another person photographed by the camera.
[0018]
An identifier indicating that some of the parameters used for compression are not stored together with the image data may be stored together with the image data. In this way, when decompressing image data, it is easy to know that a parameter is missing by an identifier, and appropriate processing such as decompression using parameters stored in a memory can be performed. Becomes possible.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a mobile phone according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a schematic configuration of a mobile phone 1 according to the present embodiment. The mobile phone 1 includes a communication unit 11, an audio input unit 12, an audio output unit 13, an operation unit 14, an imaging unit 15, an external device interface (I / F) 16, a display unit 17, and a control unit 10.
[0020]
The communication unit 11 carries a signal to be transmitted on a carrier and transmits the signal from the antenna 11a, and extracts a signal from the carrier received by the antenna 11a. The voice input unit 12 acquires voice to be transmitted, and the voice output unit 13 outputs the received voice. The operation unit 14 includes several keys associated with numbers and characters or predetermined functions, and is operated by a user to input a telephone number and a character string and to instruct an operation. The keys of the operation unit 14 include four cursor keys for moving a cursor (pointer) displayed on the display unit 17 up, down, left, and right.
[0021]
The imaging unit 15 is configured by a camera including a CCD area sensor and a lens that forms light on the CCD area sensor, and captures an image. The external device interface 16 can be provided with a communication cable, and communicates with another device such as a personal computer via the cable. The display unit 17 is composed of a liquid crystal display device and displays characters and images. The image captured by the imaging unit 15 is displayed on the display unit 17.
[0022]
The control unit 10 controls the overall operation of the mobile phone 1 and performs processing of transmitted and received voice and image data. The control unit 10 includes a CPU 10a, and control and various processes are mainly performed by the CPU 10a.
[0023]
The mobile phone 1 has a function of connecting to the Internet to download information from a web page and a function of sending and receiving e-mail. Various files can be attached to the e-mail to be sent and received, and these files include those with image data. The information to be downloaded also includes image data. The image represented by the downloaded image data or the image data attached to the received mail can be displayed on the display unit 17 in the same manner as the image captured by the imaging unit 15.
[0024]
The mobile phone 1 includes a display memory 18, a work memory 19, a storage memory 20, a program memory 21, and a parameter memory 22, in addition to the above components. The display memory 18 temporarily stores image data representing an image to be displayed on the display unit 17. The work memory 19 temporarily stores information necessary for the CPU 10a of the control unit 10 to perform control and process image data. The storage memory 20 stores and stores image data. The storage memory 20 is made of a flash memory, is rewritable, and does not lose stored contents even when power is not supplied.
[0025]
The program memory 21 stores a program describing operations performed by the CPU 10a, and the parameter memory 22 stores parameters used by the CPU 10a for control and processing of image data. These memories 21 and 22 are composed of ROMs and do not lose their stored contents even when power is not supplied.
[0026]
The mobile phone 1 has a function of displaying a two-dimensional two-dimensional image based on a single image data and a three-dimensional three-dimensional image based on two types of image data representing left and right images having parallax. It has the function of displaying images. FIG. 2 shows the principle of displaying these images.
[0027]
The liquid crystal display device of the display unit 17 is of a transmission type, includes a filter that selectively transmits red (R) light, and includes a group of pixels (referred to as R pixels) for displaying an R component of an image and green (G) light. A pixel (referred to as a B pixel) that includes a group of pixels (referred to as a G pixel) that selectively transmits and displays the G component of an image and a filter that selectively transmits the blue (B) light and displays the B component of the image. With groups. As shown in FIG. 2A, these three types of pixel groups are arranged so as to form columns in the vertical direction, and are alternately arranged in the horizontal direction in this order. Three pixels (R pixel, G pixel, B pixel) arranged in the horizontal direction represent one point of the image.
[0028]
When displaying a two-dimensional image, each point of the image is displayed continuously in the horizontal and vertical directions. Light from all pixels is directed to both the left and right eyes of the user. On the other hand, when representing a three-dimensional image, as shown in FIG. 2B, in the horizontal direction, an image for the left eye and an image for the right eye are alternately displayed for each pixel. In the vertical direction, each point of the image is continuously displayed on both the left-eye image and the right-eye image. The light of the image for the left eye is guided only to the left eye, and the image for the right eye is guided only to the right eye.
[0029]
FIG. 3 schematically shows a configuration for selectively guiding the light of the image for the left eye and the light of the image for the right eye to the left eye and the right eye when providing a three-dimensional image. The display unit 17 includes two transmissive liquid crystal panels 17a and 17b, a light guide plate 17c, and a light source 17d. The light source 17d emits white light and causes the emitted light to enter the light guide plate 17c from its end face. The light guide plate 17c has fine irregularities (not shown) on the upper surface or the lower surface. The light incident from the end surface is totally reflected on the upper and lower surfaces and guided toward the other end surface, and is emitted from the upper surface by the irregularities. Let it.
[0030]
The liquid crystal panel 17a is for displaying an image, and includes the above-described R pixel group, G pixel group, and B pixel group. The light from the light guide plate 17c is modulated by the liquid crystal panel 17a to become light representing an image. Although a polarizing plate is provided opposite to the upper and lower surfaces of the liquid crystal panel 17a, it is not shown here.
[0031]
The liquid crystal panel 17b has a transparent electrode (not shown) extending in a vertical direction (a direction perpendicular to the paper surface of FIG. 3). As shown by hatching, a stripe-shaped light shielding portion is formed when a voltage is applied. To appear. The liquid crystal panel 17b is arranged so that each light shielding portion faces between pixels of the liquid crystal panel 17a. Of the pixels arranged in the horizontal direction of the liquid crystal panel 17a, the light from the odd-numbered pixels is blocked by the light shielding portion of the liquid crystal panel 17b and does not reach the right eye, reaches only the left eye, and conversely, the even-numbered pixels Light from the pixel is blocked by the light blocking unit and does not reach the left eye, but reaches only the right eye. By alternately displaying the left-eye image and the right-eye image for each pixel, a three-dimensional image is provided to the user.
[0032]
When displaying a two-dimensional image, no voltage is applied to the liquid crystal panel 17b, and the light-shielding portion does not appear. In this case, light from all the pixels of the liquid crystal panel 17a reaches both the left eye and the right eye. A state in which a two-dimensional image is displayed with this setting is called a 2D mode, and a state in which a three-dimensional image is displayed with the setting shown in FIG. 3 is called a 3D mode.
[0033]
The image data to be downloaded via the Internet and the image data attached to the received mail include those representing a two-dimensional image and those representing a three-dimensional image. FIG. 4 schematically shows a data array of image data representing a three-dimensional image. The left-eye image data and the right-eye image data each have half the size of image data representing a two-dimensional image, and the left-eye image data and the right-eye image data are arranged for each row in the horizontal direction of the image. Image data are arranged side by side. In each image data, a set of data for R pixel, G pixel, and B pixel (referred to as R pixel data, G pixel data, and B pixel data, respectively) representing one point of the image is arranged in the horizontal direction. ing.
[0034]
When an image is displayed as it is on the basis of this image data, as shown in FIG. 5A, the image for the left eye and the image for the right eye are displayed separately on the left and right. Therefore, instead of using the image data of FIG. 4 as it is, the arrangement in the horizontal direction is changed, and the image data for the left eye and the image data for the right eye are alternately arranged for each pixel data. When the image data after the arrangement change is displayed, the image for the left eye and the image for the right eye are combined and displayed as shown in FIG. 5B. By displaying this image in the 3D mode, a three-dimensional image is provided to the user.
[0035]
The mobile phone 1 has a function of generating image data representing a three-dimensional image from image data representing a two-dimensional image. In this method, every other set of R pixel data, G pixel data, and B pixel data is extracted (thinned out) from two-dimensional image data to obtain left-eye image data. Are shifted so that the closer to the end, the larger the shift amount is, according to the position in the left-right direction, so that the right-eye image data and I do. With this function, image data representing a three-dimensional image can be obtained from two-dimensional image data acquired via the Internet or image data representing an image captured by the imaging unit 15, and a three-dimensional image can be provided. Becomes possible.
[0036]
In the present embodiment, when distinguishing left and right, as described above, the left will be the main and the right will be the subordinate, but either may be the main. “Left” and “right” in the description can be read interchangeably.
[0037]
The mobile phone 1 stores a large number of image data in the storage memory 20 as individual files. For the image data file downloaded via the Internet or the image data file attached to the received mail, the file name originally attached is given, and for the image data file representing the image captured by the imaging unit 15, Assign a predetermined file name. The user can arbitrarily change these file names.
[0038]
When displaying the image represented by the stored image data on the display unit 17 and sending the recorded image data by attaching it to an e-mail, the user displays the file names as a list on the display unit 17. Then, a desired one can be selected. The mobile phone 1 also has a function of displaying a list of thumbnail images in order to make the selection by the user easier. Image data representing a thumbnail image is created from image data acquired via the Internet or image data representing an image captured by the imaging unit 15, and stored in a file of the image data together with the original image data. deep.
[0039]
The thumbnail image can be a two-dimensional image or a three-dimensional image. 6A to 6E show display examples of thumbnail images. In these figures, a thumbnail image represented by a triangle means that the original image data represents a two-dimensional image, and a thumbnail image represented by a circle or an ellipse indicates that the original image data represents a three-dimensional image. Means to represent. Thumbnail images are uniformly displayed in a plane in the 2D mode or stereoscopically in the 3D mode.
[0040]
FIGS. 6A to 6D show display examples of thumbnail images in the 2D mode, and FIG. 6E shows an example of thumbnail images in the 3D mode. In each example, a thumbnail image created from image data representing a two-dimensional image and a thumbnail image created from three-dimensional image data are mixed.
[0041]
Image data representing a thumbnail image is created by extracting (thinning out) one set of a plurality of sets of R pixel data, G pixel data, and B pixel data from the original image data. When original image data represents a three-dimensional image, there are three methods for creating image data of a two-dimensional thumbnail image. First, as shown in FIG. 6A, it can be generated from the entire data array of FIG. Further, as shown in FIG. 6B, it can be generated from only the left-eye image data in the data array of FIG. Further, as shown in FIG. 6C, it is also possible to reduce the horizontal thinning rate by half from only the left-eye image data.
[0042]
When creating image data of a thumbnail image only from image data for the left eye, it is difficult for the user to determine whether the original image data represents a two-dimensional image or a three-dimensional image. Therefore, the dimensions of the image represented by the original image data may be indicated by symbols along with each thumbnail image. FIG. 6D shows the display of FIG. 6C with the symbols “2D” and “3D” added.
[0043]
When the original image data represents a three-dimensional image, the image data representing the three-dimensional image is created by combining the left-eye pixel data and the right-eye pixel data with the data array of FIG. Are alternately arranged, and the conversion is performed using the converted image data. When the original image data represents a two-dimensional image, image data representing a three-dimensional image is created by extracting data from the original image data to create left-eye image data. , Image data for the right eye is generated from the image data, and further converted into a format in which pixel data for the left eye and pixel data for the right eye are alternately arranged, and the converted image data is used.
[0044]
When the original image data represents a two-dimensional image, image data for the left eye is created by extracting data from the original image data, and the image data for the left eye is directly copied to be used for the right eye. The image data may be converted into a format in which pixel data for the left eye and pixel data for the right eye are alternately arranged, and the conversion may be performed using the converted image data. In this way, an image having no parallax between the left and right eyes, that is, a two-dimensional image is provided by the display in the 3D mode.
[0045]
The size of the thumbnail image is constant, and therefore, the size (the number of pixels) of the image data is also constant. On the other hand, although the size of the image captured by the imaging unit 15 is constant, the size of the image obtained via the Internet differs depending on the provider. Therefore, when creating image data representing a thumbnail image, the size of the original image is considered. Specifically, the image data of the thumbnail image is created as follows.
[0046]
First, the ratio of the horizontal size (number of pixels) of the original image to the horizontal size (number of pixels) of the thumbnail image, and the vertical size of the original image relative to the vertical size of the thumbnail image Is calculated. Then, pixel data is extracted from the original image data according to the smaller ratio to generate intermediate image data. This intermediate image data has a size that matches the thumbnail image in the direction with a small ratio. Next, in the direction in which the ratio is large, a portion of the intermediate image data that exceeds the size of the thumbnail image is deleted. As a result, image data representing a thumbnail image having a fixed size is obtained regardless of the size of the original image data.
[0047]
FIG. 7 shows an outline of the processing flow of the mobile phone 1 when acquiring image data. First, image data is obtained by downloading from the Internet, receiving an e-mail, or photographing by the imaging unit 15 (step # 10), and stores the obtained image data as a file in the storage memory 20 (# 11). Next, the obtained image data and the file name of the image data and the information added to the file are analyzed to obtain information (type) of the image data, dimensions of the image, information on the copyright, and the like (# 12). These are stored in the image data file as attributes of the image data (# 13). Further, image data representing a thumbnail image is created from the acquired image data (# 14), and the image data is stored in a file of the original image data (# 15). Finally, the image represented by the acquired image data is displayed on the display unit 17 in the 2D mode or the 3D mode according to the dimension (# 16).
[0048]
In the processing of steps # 12 and # 13, the working memory 19 is used. FIGS. 8A and 8B schematically show the structures of the contents stored in the work memory 19 and the storage memory 20, respectively. As shown in FIG. 8B, a file for each image data is stored in the storage memory 20, and a series of numbers are assigned to all the files. Here, an example is shown in which the file with the number 1 is deleted and no longer exists.
[0049]
Each file in the storage memory 20 includes management information, thumbnail image data, and image data. The management information includes the type (format) of the image, the dimension attribute of the image, the copyright attribute, the file name, and the image size (the number of pixels in the horizontal and vertical directions of the image data). The thumbnail image data is compressed and stored, and information on the compression processing is added. Further, the image data is compressed at the time of acquisition, and is stored as it is together with information on the compression processing. As described above, image data includes data representing a two-dimensional image and data representing a three-dimensional image.
[0050]
The work memory 19 stores the management information of all the image data files in the storage memory 20 and the number of the first image data. Further, the number of the next image data is stored for each management information of each image data. In the example of FIG. 8A, the number of the first image data (image number) is “2”, and the number of the next image data after the second image data is “3”. In the management information of the last image data, “0” is stored as the number of the next image data (not shown). Further, when the image data is obtained via the Internet, information indicating the type (format) of the image added to the image data and information regarding the copyright are stored in a predetermined area of the working memory 19. (Not shown).
[0051]
The control unit 10 reads out the management information of all the image data from the storage memory 20 and stores it in the work memory 19 at the start of the power supply. Thereafter, each file in the storage memory 20 is managed with reference to the work memory 19. The number of the image data is used for management. When a file is deleted from the storage memory 20, the corresponding management information is deleted from the work memory 19, and the number of the next image data in the work memory 19 is appropriately changed. When new image data is stored in the storage memory 20, the management information is stored in the work memory 19, and the number of the next image data in the work memory 19 is appropriately changed.
[0052]
Generally, image data provided via the Internet is compressed according to the JPEG method, and image data representing an image captured by the imaging unit 15 is also compressed according to the JPEG method. However, the extension of the file name of the JPEG image data provided via the Internet is “JPEG” or “JPG” when representing a two-dimensional image, and “STJ” when representing a three-dimensional image. Have been. According to the mobile phone 1, the extension of the file name of the image data representing the captured two-dimensional image is set to “JPEG” or “JPG”, and the three-dimensional image generated from the image data is represented. For image data, the extension of the file name is “STJ”.
[0053]
The mobile phone 1 has a function of generating, from two or more pieces of image data representing moving images, image data representing some intermediate images, and displaying a moving image with smooth movement. . Such an image is called an E-animation. The E-animation also has a two-dimensional two-dimensional image and a three-dimensional three-dimensional image. Further, the image data of the E animation is provided via the Internet. The provided E-animation image data is also compressed according to the JPEG method. However, the extension of the file name of the E-animation image data is set to “NVA” regardless of whether it represents a two-dimensional image or a three-dimensional image. In the mobile phone 1, the extension of the file name is set to "NVA" for all the E-animation image data.
[0054]
FIG. 9 shows the processing in steps # 12 to # 15 of the processing at the time of acquiring the image data shown in FIG. 7 in more detail. First, image data is read from the storage memory 20 (step # 102). At the time of reading, the image data is decompressed using the information of the compression processing attached to the image data. Then, the type of the image is determined with reference to the aforementioned predetermined area of the working memory 19 (# 104). When image data is obtained by photographing with the imaging unit 15, nothing is stored in the predetermined area of the working memory 19, but the type of the image is "JPEG" at this time.
[0055]
Next, the image data is analyzed to determine whether the image is an E-animation image (# 106). If it is not E animation, the file name is checked to determine whether the extension is "STJ"(# 108). If the extension is "STJ", the 2D / 3D attribute is set to "3D"(#114); otherwise, the 2D / 3D attribute is set to "2D"(# 116). The 2D / 3D attribute is stored in a predetermined area of the working memory (# 118). If it is E animation image data, the image data is analyzed to determine whether it is two-dimensional image data or three-dimensional image data (# 110). In the case of three-dimensional image data, the 2D / 3D attribute is set to "3D"(# 114), and in the case of two-dimensional image data, the 2D / 3D attribute is set to "2D"(# 116).
[0056]
The presence / absence of information related to copyright is determined with reference to the above-mentioned predetermined area of the working memory 19 (# 120). If there is, the copyright attribute is determined to be “present” (# 122). "None"(# 124). Further, image data of the thumbnail image is created (# 126), and the created image data is compressed (# 128).
[0057]
Next, the image number N assigned to the image data in the storage memory 20 is set to 1 (# 130). Then, it is checked whether or not the management information of the image number N is stored in the work memory 19 (# 132). If the management information is stored, 1 is added to the image number N (# 134), and the process proceeds to step # 132. Return. If the image number N is not stored, the image data of the compressed thumbnail image, the image type attribute, the 2D / 3D attribute, and the compressed thumbnail image are stored in the file of the image data stored in step # 11 of FIG. And the copyright attribute is stored and saved (# 136). At this time, the number of the file (image data) is set to N. Further, an image type attribute, a 2D / 3D attribute, and a copyright attribute are stored as management information in the work memory 19 (# 138), and the number of the management information is set to N.
[0058]
Further, the next image number to be added to the management information stored in the work memory 19 is set as the first image number at that time (# 140), and the first image number is set as N (# 142).
[0059]
The compression of the image data of the thumbnail image in step # 128 is performed in accordance with the JPEG method. When the image data is stored in step # 136, the parameters used for the compression processing are also stored in order to enable later decompression. . Here, since the image data of the thumbnail image is used only by the mobile phone 1, it is possible to make some parameters constant at all times and to make them common to all the image data. If such common parameters are stored for each image data of the thumbnail image, the storage capacity of the storage memory 20 is wasted. Therefore, common parameters requiring a large storage capacity are not stored for each image data but are stored in the parameter memory 22 (see FIG. 1).
[0060]
FIG. 10 shows parameters used in the compression processing according to the JPEG method. Compression is performed in two stages of Huffman coding and subsequent quantization, and a Huffman table and a quantization table are used as parameters, respectively. In the portable telephone 1, the Huffman table (symbol DHT) is made common to the image data of all the thumbnail images, and is excluded from the parameters to be added to the image data of the thumbnail images and stored. The size of the Huffman table is about 400 bytes, which corresponds to, for example, about 45% of the image data of a 48 × 48 dot thumbnail image using standard compression and the size of all parameters (about 900 bytes). By not storing the Huffman table, the storage capacity of the storage memory 20 can be greatly saved. Note that the quantization table (symbol DQT) depends on the image data after Huffman coding, and therefore needs to be stored separately for each image data.
[0061]
When displaying the thumbnail image, the compressed image data is inversely quantized using a quantization table stored together with the image data, and further inversely encoded using a Huffman table stored in the parameter memory 22. (Decryption).
[0062]
For the acquired image data, all parameters including the Huffman table are stored. This is because Huffman tables are not common for image data provided via the Internet. However, a common Huffman table may be stored in the parameter memory 22 for the image data acquired by the imaging unit 15, and the Huffman table may not be stored by performing encoding using the table. . In this way, the storage capacity of the storage memory 20 is further saved.
[0063]
When the Huffman table is not stored together with the image data, information indicating that the Huffman table is not stored may be added to the image data and stored. This makes it clear that a common Huffman table should be added when the image data is attached to an e-mail and transmitted. When image data for which the Huffman table is not stored is not allowed to be attached to an e-mail, a message indicating that attachment to an e-mail is not possible may be displayed together with a thumbnail image as described later. it can. The information indicating that the Huffman table is not stored is preferably included in the management information as in the case of the above-described 2D / 3D attribute and copyright attribute. It is possible to quickly determine the presence or absence of the Huffman table.
[0064]
The image data for which the Huffman table is not stored may be allowed to be provided to another device as it is. In this case, information indicating that the Huffman table is omitted is added to the image data. The device that has acquired such image data knows that the Huffman table has been omitted from the added information, and can take appropriate measures.
[0065]
For example, when the mobile phone 1 obtains such image data from another mobile phone having the same function, decoding is performed using a common Huffman table, so that an image represented by the obtained image data is obtained. It is possible to display. When decoding cannot be performed using a common Huffman table, for example, an “x” mark or a “not displayable” character may be displayed instead of an image to indicate that display is not possible. Providing image data without the Huffman table also leads to a reduction in the amount of communication, and reduces the time required for downloading and sending and receiving e-mail.
[0066]
FIG. 11 shows an outline of a processing flow when an electronic mail is created and transmitted. First, an e-mail is created according to the input operation of the user (step # 20). At this time, a destination mail address is also set. Next, it is determined whether or not it is instructed to attach the image data to the created e-mail (# 21). When the instruction to attach the image data is not instructed, the electronic mail is transmitted as it is (# 25).
[0067]
When an instruction to attach image data is given, a list of thumbnail images is displayed (# 22). At this time, a thumbnail image is displayed regardless of whether the original image data represents a two-dimensional image or a three-dimensional image. Then, the image data designated by the user is selected (# 23). At this time, based on the dimensions of the image, the copyright, etc., image data that may be attached to the e-mail is determined in advance, and only the image data that may be attached can be selected. Finally, the image data is attached to the e-mail (# 24) and transmitted (# 25).
[0068]
FIG. 12 shows the processing in steps # 22 and # 23 in more detail. First, the maximum number M0 of thumbnail images that can be displayed at one time on the display unit 17 is set, and the display position M of the thumbnail images is set to 1 (step # 202). For example, when three images are displayed horizontally and three images are displayed vertically, M0 is 9, and in this case, the display position M at the center of the right end is 6. Next, the first image number N is read from the working memory 19 (# 204).
[0069]
Then, it is determined whether or not the image number N is 0 (# 206). If not, it is determined whether or not the display position M is equal to or less than the maximum number M0 (# 208). When the display position M is equal to or less than the maximum number M0, the thumbnail image data of the image number N is read from the storage memory 20 (# 210), decompressed (# 212), and the decompressed image data is stored in the display memory 18 Is stored in the area corresponding to the display position M (# 214).
[0070]
Next, the 2D / 3D attribute is determined with reference to the N-th management information of the working memory 19 (# 216) (# 218). When the 2D / 3D attribute is "2D", the N-th management information in the working memory 19 is referred to (# 220), and the copyright attribute is determined (# 222). When the copyright information is "none", the N-th image data is selectable (may be attached to the mail), and that fact is stored in a predetermined area of the working memory 19 (# 224).
[0071]
If the 2D / 3D attribute is "3D" in the determination in step # 218, or if the copyright attribute is "present" in the determination in step # 222, the selection is disabled (# 226). Further, in order to clearly indicate that selection is not possible, the image data in the display memory 18 is modified to add data representing a diagonal line (# 228).
[0072]
Following these processes, the data is displayed on the display unit 17 using all the data in the display memory 18 (# 230). As a result, the number of thumbnail images equal to the number of times the process of step # 214 has been performed is displayed. Next, the next image number N is read from the working memory 19 (# 232), the display position M is increased by 1 (# 234), and the process returns to step # 206.
[0073]
When the image number N is 0 in the determination in step # 206, that is, when the thumbnail images of all the image data have been displayed, or when the display position M exceeds the maximum number M0 in the determination in step # 208, When there is no more room for displaying the thumbnail image, it is determined whether or not the operation unit 14 has been operated to instruct to scroll the display (# 236). When a scroll instruction is given, the display position M is updated (# 238), and the image number N is also updated (# 240). For example, when three thumbnail images are displayed side by side, the display position M is increased or decreased by three. Then, the process returns to step # 206.
[0074]
If there is no scrolling instruction, it is determined whether or not a determination has been instructed (# 242). This instruction is given by the user operating a predetermined key of the operation unit 14. Before giving this instruction, the user operates the cursor key of the operation unit 14 to position the cursor on the display unit 17 above the thumbnail image to be selected. When there is no instruction for determination, the process returns to step # 236.
[0075]
When the determination is instructed, the information stored in step # 224 or # 226 is read from the work memory 19 for the image number corresponding to the display position where the cursor is located, and whether the selection is possible or not is possible. Is determined (# 244). If the selection is not possible, the process returns to step # 236. If the selection is possible, the image data of the image number is read from the storage memory 20 (# 246), and the file name is read from the work memory 19 (# 248). Thereafter, in step # 24 of FIG. 11, the read image data is given the read file name and attached to the e-mail.
[0076]
FIG. 13 shows an example of a thumbnail image represented by the image data modified in step # 228. FIG. 13A shows the thumbnail image of FIG. 6C with diagonal lines, and FIG. 13B shows the thumbnail image of FIG. 6E with diagonal lines. By adding the oblique lines in this manner, it is possible to clarify image data that is not allowed to be attached to an e-mail. Instead of adding hatching, other indications such as “impossible” may be added to clarify that attachment is not allowed. Further, it may be clarified that attachment is not allowed by using a monochrome image without color. When displaying a list of thumbnail images not for attachment to an e-mail but for display of images, as shown in FIGS. 6 (a) to 6 (e), it should be noted that attachment is not permitted. The display of the diagonal lines shown is not performed.
[0077]
FIG. 14 shows an example of a criterion for judging whether or not attachment to an electronic mail is possible. Of the image data created by the JPEG system, two-dimensional image data obtained via the Internet is usually accompanied by information on copyright, and cannot be attached based on the copyright attribute. The two-dimensional image data acquired by the imaging unit 15 determines whether or not to attach based on the copyright attribute and the 2D / 3D attribute. However, from the 2D / 3D attribute, the attachment is permitted. It can be attached from the attribute. However, the mobile phone 1 also has a function of adding information regarding copyright to image data representing an image captured by the imaging unit 15, and when the user adds information regarding copyright, the function is based on the copyright attribute. Cannot be attached.
[0078]
Of the image data created by the JPEG method, three-dimensional image data acquired via the Internet is usually accompanied by information on copyright, and cannot be attached based on the copyright attribute. Further, even if information regarding copyright is not added and the copyright attribute indicates “OK”, the 2D / 3D attribute indicates “NO”. Image data (file name extension is STJ) created from two-dimensional image data by the three-dimensional conversion function is not allowed due to the 2D / 3D attribute. This is because portable telephones that can display three-dimensional images are not widely used, and there is a high possibility that transmitting three-dimensional image data is wasted.
[0079]
E-animation image data (file name extension is NVA) is a copyright attribute or image type (image type) regardless of whether it represents a two-dimensional image or a three-dimensional image. ) Cannot be attached. Even if the copyright attribute allows, the image type is always NVA, and the image data of the E-animation cannot always be attached.
[0080]
In the mobile phone 1, some E-animation image data in which the central part is blank, that is, only the peripheral part, is stored in the storage memory 20, and these image data and the image captured by the imaging unit 15 are stored. It has a function of synthesizing with image data and displaying it as an image in which a peripheral portion corresponding to a frame moves smoothly. There are two-dimensional and three-dimensional E-animation image data, and any image data cannot be attached to a mail based on its image type (NVA). Mobile phones capable of displaying E-animation images, like mobile phones capable of displaying three-dimensional images, have not yet become widespread, and transmitting E-animation image data wastefully. Because it is easy to become.
[0081]
As described above, the mobile phone 1 can communicate with another device such as a personal computer via a cable connected to the external device interface 16 (see FIG. 1). The information that can be transmitted to other devices by this communication includes image data. In this case as well, whether the image data can be transmitted is determined in the same manner as whether the image data can be attached to an e-mail. As a result, the copyright of the image data creator is reliably protected, and unnecessary transmission can be avoided.
[0082]
Here, a portable telephone is described as an example of the electronic device that compresses and stores the image data. However, the present invention is not limited to the portable telephone, and the present invention is not limited to the portable telephone. The present invention can be applied to various types of electronic devices that handle image data, including various types of portable devices.
[0083]
【The invention's effect】
An electronic device that compresses image data representing an image and stores the compressed image data together with parameters used for compression, as in the present invention, includes a memory that stores parameters independent of image data among parameters used for compression. Thus, at least a part of the compression of the image data is performed using the parameters stored in the memory, and the parameters stored in the memory are excluded from the parameters stored together with the image data. This makes it possible to save the storage capacity required for storing the image data, and to store a large amount of image data. Further, even when image data is provided to another by mistake, decompression becomes difficult due to lack of some parameters, and copyright and portrait right are protected.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a schematic configuration of a mobile phone according to an embodiment of the present invention.
FIG. 2 is a view showing the principle of displaying a two-dimensional image and a three-dimensional image in the portable telephone.
FIG. 3 schematically shows a configuration of the portable telephone for selectively guiding light of an image for a left eye and light of an image for a right eye to a left eye and a right eye when providing a three-dimensional image. FIG.
FIG. 4 is a diagram schematically showing a general data array of image data representing a three-dimensional image.
FIG. 5 is a diagram schematically illustrating an example of an image displayed based on image data representing a three-dimensional image.
FIG. 6 is a diagram schematically showing a display example of a thumbnail image on the portable telephone.
FIG. 7 is a flowchart showing an outline of the flow of processing when acquiring image data in the portable telephone.
FIG. 8 is a diagram schematically showing a structure of contents stored in a work memory and a storage memory of the portable telephone.
FIG. 9 is a flowchart showing details of the processing in steps # 12 to # 15 in the processing at the time of acquiring the image data shown in FIG. 7;
FIG. 10 is a view showing parameters used in compression processing by the JPEG method.
FIG. 11 is an exemplary flowchart showing an outline of a processing flow when an electronic mail is created and transmitted in the portable telephone.
FIG. 12 is a flowchart showing details of processing in steps # 22 and # 23 of the processing related to the e-mail shown in FIG. 11;
FIG. 13 is a diagram showing an example of a thumbnail image displayed when selecting image data to be attached to an electronic mail in the portable telephone.
FIG. 14 is a diagram showing criteria for judging whether image data can be attached to electronic mail in the portable telephone.
[Explanation of symbols]
1 Mobile phone 10 Control unit 10a CPU
Reference Signs List 11 Communication unit 11a Antenna 12 Audio input unit 13 Audio output unit 14 Operation unit 15 Imaging unit 16 External device interface 17 Display unit 17a Image display liquid crystal panel 17b Light shielding liquid crystal panel 17c Light guide plate 17d Light source 18 Display memory 19 Work memory 20 Storage Memory 21 Program Memory 22 Parameter Memory

Claims (6)

In an electronic device that compresses image data representing an image and stores the compressed image data together with parameters used for compression,
Providing a memory that stores parameters that do not depend on image data among the parameters used for compression, performing at least part of the compression of the image data using the parameters stored in the memory, and from the parameters stored with the image data. An electronic device characterized by excluding parameters stored in a memory. Compress image data according to JPEG method,
The electronic device according to claim 1, wherein a Huffman table used in the encoding step is stored in a memory. 2. The electronic apparatus according to claim 1, wherein parameters stored in a memory are used when reproducing image data before compression by inverse processing of compression. 2. The electronic apparatus according to claim 1, wherein the image data to be compressed is created by extracting from image data representing an image larger than the image represented by the image data. 2. The electronic apparatus according to claim 1, further comprising a camera that captures an image, wherein the image data to be compressed represents an image captured by the camera. 2. The electronic apparatus according to claim 1, wherein an identifier indicating that a part of the parameters used for compression is not stored together with the image data is stored together with the image data.

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