1. Technical Field
The present invention relates to a technique to play back a taken image stored in the form of digital data to be displayed on the monitor screen.
2. Related Art
Advancements in the electronic-related technique, most notably computers, have made it common nowadays to output a taken image as digital data. A large volume of images can be stored electronically by saving images of pictures taken by a digital camera (electronic still camera) in the form of digital data. In addition, the content of an image can be confirmed readily by reading out the digital data to be displayed on the monitor screen.
Under these circumstances, as is disclosed, for example, in JP-A-2006-318165, there has been proposed a technique to print out desired taken pictures alone by allowing the user to confirm the contents (that is, the subject, the composition, the focus, and so forth) of taken images stored in the form of digital data on the monitor screen before he prints out the taken images.
However, confirming taken images on the monitor screen has a limitation, and this limitation poses a problem that properly taken images alone are not necessarily printed out. To be more specific, because a taken image is normally printed out on paper of a size bigger than the monitor screen, there may be a case where the presence of blur in an image resulting from defocusing or hand shaking that was unnoticeable when the image was confirmed on the monitor screen becomes noticeable for the first time when the image is printed out, and the printed image is wasted after all. It is possible to confirm blur or shaking on the monitor screen by displaying as large an image as the print size on the monitor screen. However, because only a part of the taken image is displayed, the user has to make confirmation more than once by changing the displayed area. In addition, in order to confirm the entire subject or the composition, it is still necessary to display the entire taken image on the monitor screen. The advantage achieved by handling the taken images in the form of digital data that the contents of the taken images can be readily confirmed on the monitor screen is thus lessened markedly.
An advantage of some aspects of the invention is to provide a technique for enabling the user to choose proper images alone by making it possible to readily confirm images outputted as digital data on the monitor screen.
An image display apparatus according to one aspect of the invention adopts the configuration as follows.
That is, an image display apparatus displays a digital image on a confirmation screen, and includes a blur variance value acquisition unit that acquires a blur variance value, which is an index relating to a difference in amount of blur between images obtained when the digital image is printed out and when the digital image is displayed on the confirmation screen, a blur amount variance correction unit that corrects the difference in amount of blur for the digital image displayed on the confirmation screen according to the blur variance value with respect to the digital image printed out, and an image display unit that displays the digital image for which the difference in amount of blur has been corrected on the confirmation screen.
In addition, an image display method according to another aspect of the invention corresponding to the image display apparatus described above is an image display method for displaying a digital image on a confirmation screen. The method includes acquiring a blur variance value, which is an index relating to a difference in amount of blur between images obtained when the digital image is printed out and when the digital image is displayed on the confirmation screen, correcting the difference in amount of blur for the digital image displayed on the confirmation screen according to the blur variance value with respect to the digital image printed out, and displaying the digital image for which the difference in amount of blur has been corrected on the confirmation screen.
According to the image display apparatus and the image display method according to the aspects of the invention, a blur variance value, which is an index relating to a difference in amount of blur between images obtained when the digital image is printed out and when the digital image is displayed on the confirmation screen, is acquired. Herein, as the blur variance value, any index can be adopted as long as it is an index relating to a difference in amount of blur between the images. For example, a ratio of the size of the confirmation screen and the size of print paper (or the printed image) can be used as the blur variance value. Alternatively, instead of a simple ratio, a value that takes into account a distance from an observer who observes the image to the image can be used as the blur variance value. Further, by quantifying a difference in amount of blur by an experimental method, it is possible to use an amount of blur that reflects, for example, a difference in impression or in vision between the images obtained when the image is printed out and when the image is displayed on the screen. When the blur variance value has been found in the manner described above, the difference in amount of blur is corrected according to the blur variance value, after which the corrected digital image is displayed on the confirmation screen. When the difference in amount of blur is corrected according to the blur variance amount, for example, a two-dimensional filter that is determined according to the blur variance value can be applied to the digital image displayed on the confirmation screen.
It is normal that the digital image displayed on the confirmation screen has an amount of blur different from that in the image obtained when the digital image is printed out. Accordingly, even when the image is confirmed on the confirmation screen, it can happen that a defocused image is printed out wastefully. To eliminate this inconvenience, by displaying the image on the confirmation screen in a state where a correction is made to the difference in amount of blur between images when the image is displayed on the conformation screen and when the image is printed out, the user is able to choose proper images alone. It is thus possible to avoid an image that is actually out of focus from being printed out wastefully. In addition, because hand shaking or the subject shaking can be deemed as a state where blurring is occurring in one direction, it is possible to avoid an image with the hand shaking or the subject shaking from being printed out wastefully.
In order to correct the difference in amount of blur, it is sufficient to correct an amount of blur in the image displayed on the confirmation screen to approximate to an amount of blur in the image obtained when printed out, and amounts of blur in the image displayed on the screen and in the printed image are not necessarily corrected to be equal. It goes without saying, however, that correcting the amounts of blur to be equal is preferable because the user becomes able to confirm the image obtained when it is printed out more appropriately on the confirmation screen.
The image display apparatus according to the aspect of the invention may be configured in such a manner that the digital image is divided into block of a specific size to obtain the blur variance value block by block, so that the difference in amount of blur is corrected by applying a two-dimensional filter corresponding to the blur variance value to the digital image block by block.
Because an amount of blur differs from one position to another in the image, an amount of blur can be corrected more appropriately by dividing the image into blocks and correcting an amount of blur block by block, which in turn makes it possible to display the image appropriately on the confirmation screen.
The image display apparatus according to the aspect of the invention may be configured in such a manner that the difference in amount of blur is corrected using the two-dimensional filter of a larger filter size as the difference in amount of blur becomes larger.
For example, in a case where a given image is to be blurred considerably, the image can be blurred more appropriately or efficiently when a two-dimensional filter of a larger filter size is used. In light of this fact, in a case where a difference in amount of blur between the image displayed on the confirmation screen and the printed image is corrected, the image to be displayed on the confirmation screen can be corrected appropriately or efficiently by using a larger two-dimensional filter as the difference in amount of blur to be corrected becomes larger.
Alternatively, the image display apparatus according to the aspect of the invention may be configured in such a manner that an image size in which the digital image is to be printed out is acquired before the blur variance amount is acquired, so that the blur variance value is acquired according to the image size.
Strictly speaking, an amount of blur when the digital image is printed out depends on the image size. Hence, strictly speaking, the blur variance value, which is an index relating to a difference in amount of blur between images obtained when the digital image is printed out and when the digital image is displayed on the confirmation screen, depends on the image size. Accordingly, by acquiring the image size in advance before the blur variance value is acquired, it is possible to acquire a more precise blur variance value, which makes it possible to display the image in which the amount of blur has been corrected more accurately on the conformation screen.
In this instance, the blur variance value may be acquired in the manner as follows. That is, the blur variance value is pre-stored in correlation with the combination of an amount of blur contained in the digital image and the image size. Accordingly, the pre-stored blur variance value is acquired on the basis of an amount of blur extracted from the digital image and the image size.
By pre-storing the blur variance value correlated with the combination of the amount of blur contained in the digital image and the image size in the manner described above, it is possible to acquire the appropriate blur variance value promptly on the basis of the amount of blur extracted from the digital image and the image size, which makes it possible to display the image on the confirmation screen by correcting the image to be displayed thereon appropriately and promptly.
The image display apparatus according to the aspect of the invention may be configured in such a manner that in a case where an amount of correction for an amount of blur becomes larger than a predetermined amount, the amount of correction for the difference in amount of blur is fixed to this predetermined amount. In this instance, the fixed predetermined value can be a value determined in reference to the size of the confirmation screen.
When an amount of blur in the image displayed on the confirmation screen becomes too large, the user views the magnitude of an amount of blur in relation with the size of the screen rather than the magnitude itself of an amount of blur. Accordingly, by configuring in such a manner that the amount of correction is limited to the predetermined amount in a case where an amount of correction for an amount of blur becomes larger than the predetermined amount, it becomes possible to avoid an amount of blur in the image displayed on the confirmation screen from becoming too large. It is thus possible to display an image in which an amount of blur has been corrected appropriately on the confirmation screen.
Further, according to still another aspect of the invention, a program to execute the image display method described above can be achieved with a computer by reading and running the program on the computer to achieve specific functions. The invention therefore includes an implementation as a program as follows. That is, a program according to still another aspect of the invention corresponding to the image display method described above is a program that is run on a computer to execute a method for displaying a digital image on a confirmation screen. The program causes the computer to achieve a blur variance value acquisition function of acquiring a blur variance value, which is an index relating to a difference in amount of blur between images obtained when the digital image is printed out and when the digital image is displayed on the confirmation screen, a blur amount variance correction function of correcting the difference in amount of blur for the digital image displayed on the confirmation screen according to the blur variance value with respect to the digital image printed out, and an image display function of displaying the digital image for which the difference in amount of blur has been corrected on the confirmation screen.
By reading and running the program on the computer to achieve the respective functions as above, the user is able to choose proper images alone on the confirmation screen. It is thus possible to avoid an image that is actually out of focus from being printed out wastefully.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
For clear understating of the contents of the invention, embodiments will be described regarding the points and in the order as follows: the configuration of apparatus, finish confirmation processing, a first modification, and a second modification.
The control unit 300 has on board an operation panel 302 used by the user when he operates the printer 10, a loading slot 304 to insert an external memory medium, such as a memory card, a USB terminal 308 to enable data reception and transmission with an external device, and so forth. Also, the control unit 300 incorporates therein a CPU, a ROM, a RAM, and so forth. The user of the printer 10 inserts a memory medium in which are stored images taken by a digital camera or the like into the loading slot 304 and chooses images while he confirms the images on a monitor screen 306 provided to the operation panel 302. Then, the images thus chosen are printed out in the printer unit 200. Also, by connecting a digital camera to the printer 10 via the USB terminal 308, the user becomes able to choose images stored in the digital camera while confirming the images on the monitor screen 306 so that the chosen images are printed out in the printer unit 200.
It should be noted that the size of the monitor screen 306 is different from the size of an image obtained by printing, and normally the monitor screen 306 is smaller than the print image. Accordingly, because an image to be printed out is displayed on the monitor screen 306 in a scaled-down state, it can happen that an image that looked well-focused when confirmed on the monitor screen 306 is out of focus when actually printed out. Likewise, it can happen that a printed image is wasted because hand shaking or motion blur of the subject that was unnoticeable when confirmed on the monitor screen 306 becomes noticeable when actually printed out. Enlarging a part of the image displayed on the monitor screen 306 with the aim of avoiding such inconveniences makes it difficult to confirm the entire image. In addition, because the allowable degree of blur or shaking can actually vary from one part to another in the image, it is necessary to view the entire image by also taking the degree of blur or shaking into account, which is, however, difficult to achieve with the small monitor screen 306. To overcome such inconveniences, the printer 10 of the embodiment displays an image as described below for enabling the user to view the entire image by taking the degree of blur or shaking into account even on the monitor screen 306.
The printer 10 of the embodiment is configured in such a manner that when images stored in a recording medium or a digital camera are read out and displayed on the monitor screen 306 and the user finds an image he wishes to be printed out, finish confirmation processing described below is started when he presses a specific button on the operation panel 302 while this image is being chosen. This configuration enables the user to confirm an image that will be actually obtained in print on the monitor screen 306.
When the finish confirmation processing is started, print size in which the image is to be printed out (for example, whether the image is to be printed on L-size paper or A4-size paper) is acquired first (Step S100). The print size in which an image is to be printed out may be pre-set in the printer 10 so that the setting content thereof is acquired at the time of printing, or the user may be requested to input the desired print size.
Subsequently, processing to read out image data corresponding to the image being displayed on the monitor screen 306 from a recording medium or a digital camera is performed (Step S102). More specifically, because the monitor screen 306 has a small screen size and the screen is formed of a matrix of fewer pixels, the stored image data is displayed in a resolution-converted state, for example, by skipping some pixels. Accordingly, not the resolution-converted image data being displayed on the monitor screen 306 but the image data saved in the storage medium or the digital camera is read out.
The image thus read is then divided into plural blocks (Step S104).
Initially, one block (target block) as a block to be processed is chosen (Step S106). In
In an image taken by a digital camera, because the edge occurs along the contour of an object and the gradient value varies abruptly at such an edge, the edge width in nature should take an extremely small value. In light of the foregoing, the edge width obtained as described above can be deemed as directly indicating an amount of blur in the image. Also, because hand shaking can be deemed as blur with a directional property, it is possible to extract an amount of shaking in the same manner as above. Processing to extract an amount of blur (and an amount of shaking) in the target block chosen earlier is performed as described above in Step S108 detailed in
The method for extracting an amount of blur (and an amount of shaking) of the target block is not limited to a method using the Sobel filter as described above, and any other suitable method can be used as well. For example, the image data in a digital camera is normally saved in the format called JPEG. According to JPEG format, image data is divided into a matrix of blocks each having a specific number of pixels (normally 8 pixels), and the image data of each block is separated into a direct current component and alternating current components at respective frequencies. By cutting high frequency components having a little influence on the image quality, it becomes possible to save a compressed image. The alternating current components of the image can be in the horizontal direction or the vertical direction or a direction as the combination thereof. Consequently, coefficients (DCT coefficients) of the respective components when the image data is disassembled into the direct current component and the various alternating current components are saved in the JPEG format.
When an amount of blur (and an amount of shaking) of the target block has been extracted as described above (Step S108 in
Viewing angle [deg]=(360/π)arctan(W/2L).
For example, assume that the size W of the monitor screen 306 equipped to the printer 10 is 70 mm and the distance L when the monitor screen 306 is observed is 500 mm, then the viewing angle of the monitor screen 306 is about 8 deg. In a case where the print size is set to the so-called L size, it is assumed that the size W of a printed image is about 90 mm and the distance L to the image when the printed image is confirmed is 300 mm. Then, the viewing angle of the printed image is about 17.2 deg. Consequently, in comparison with a case where the image is printed on L-size paper, the image is displayed on the monitor screen 306 in a state where it is scaled down to about 1/2.2. Conversely, by displaying the image on the monitor screen 306 by increasing an amount of blur extracted from the target block by 2.2 times, it is thought that the image can be displayed with blur (or shaking) at the degree same as the degree when printed on L-size paper.
Hence, in a case where an amount of blur detected from the target block is 10 pixels as shown in
As has been described, the finish confirmation processing detailed in
For example, assume that an image saved in a recording medium is composed of 2000 pixels in the width direction while the monitor screen 306 is formed of 320 pixels in the width direction. Then, in order to display the image saved in the recording medium on the monitor screen 306, 2000 pixels are subjected to resolution conversion to 320 pixels. Accordingly, in the case of a two-dimensional filter of a 13 by 13 matrix of pixels, we get 320*13/2000=2.08. Hence, it is sufficient to use a filter of a 2 by 2 matrix of pixels (in practice, because the filter size takes an odd number, a 3 by 3 matrix of pixels). In the case of a Gaussian filter of a 25 by 25 matrix of pixels, we get 320*25/2000=4. Because the filter size takes an odd number, it is sufficient to use a Gaussian filter of a 5 by 5 matrix of pixels. In this manner, once the filter size is determined, the correction filter can be readily generated.
Subsequently, the correction filter thus generated is applied to the image being displayed on the monitor screen 306 (Step S112), and whether all the blocks have been processed is determined (Step S114). In a case where there are blocks that have not been processed (Step S114: no), the flow returns to Step S106 and one new target block is chosen to apply the processing described above to this new target block. This operation is performed repetitively until it is determined that all the blocks have been processed (Step S114: yes). Then, the image to which the correction filter has been applied is displayed on the monitor screen 306 (Step S116), after which the finish confirmation processing detailed in
The printer 10 of the embodiment described above is capable of displaying an image on the monitor screen 306 with an amount of blur (and an amount of shaking) at about the same degree as blur (or shaking) in an actually printed image by performing the finish confirmation processing detailed in
Strictly speaking, blur or shaking is inevitably present somewhere across the entire image, and merely whether the degree of blur or shaking is allowable is concerned. Also, because whether blur or shaking is allowable closely relates to the subject or the composition, it is difficult to make a determination unless the entire image is viewed. In this regard, the finish confirmation processing described above enables the user to confirm the degree of blur or the degree of shaking in each part of the image while the entire image is being displayed on the monitor screen 306. Accordingly, the user is able to determine appropriately whether the degree of blur or shaking is allowable without having to actually print out the image. It is thus possible to avoid in a reliable manner such an event that an image with considerable blur or shaking at unallowable degree is printed out wastefully.
The embodiment described above can be modified in various manners. Hereinafter, such modifications will be briefly described.
In the embodiment described above, when an amount of blur in the image saved in a recording medium or a digital camera is extracted, how many pixels should be blurred is determined by multiplying an amount of blur by a proportional coefficient depending on the difference in viewing angle between images. Accordingly, more pixels have to be blurred as an amount of blur in the original image increases.
However, when an amount of blur in the image displayed on the monitor screen 306 is increased to the extent that it can be compared with the monitor screen 306 (for example, about 1/10 of the monitor screen 306), an amount of blur (or an amount of shaking) is confirmed by comparison with the size of the monitor screen 306. Consequently, although an amount of blur itself on the monitor screen 306 is about the same as an amount of blur in an actually printed image, the former seems larger than the actual amount of blur due to the comparison with the monitor screen 306.
To avoid such an inconvenience, in a case where an amount of blur in a saved image reaches or exceeds a specific value (or in a case where an amount of blur on the monitor screen 306 reaches or exceeds a specific value), an amount of blur on the monitor screen 306 may be corrected by a predetermined amount regardless of the amount of blur in the saved image.
In the embodiment described above, when an amount of blur in a saved image is extracted, an amount of blur on the monitor screen 306 is calculated to make the viewing angles equal, after which the filter size is determined to achieve the amount of blur thus calculated. However, instead of calculating an amount of blur on the monitor screen 306 on the basis of the viewing angles, an amount of blur on the monitor screen 306 may be found by actually conducting a sensory test.
Also, in this case, instead of the correlation shown in
While the image display apparatus has been described by way of the embodiment and modifications thereof, the invention is not limited to these embodiment and modifications, and can be practiced in various manners without deviating from the scope of the invention.
The entire disclosure of Japanese Patent Application No. 2007-179326, filed Jul. 9, 2007 is expressly incorporated by reference herein.
Number | Date | Country | Kind |
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2007-179326 | Jul 2007 | JP | national |