DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

[0032] FIG. 1 is a block diagram showing the electrical structure of a digital still camera illustrative of a preferred embodiment of the present invention.

[0033] The overall operation of the digital still camera is controlled by a CPU 21 .

[0034] The digital still camera includes operating switches 18 and a shutter switch 19 . The operating switches 18 include a mode switch for setting various modes such as a still-picture imaging mode and a playback mode, a frame-advance button for applying a playback frame-advance command and a frame-back button for applying a playback frame-back command. Output signals from the operating switches 18 and shutter switch 19 are input to the CPU 21 .

[0035] An arrangement may be adopted in which the digital still camera is provided with freely rotatable jog dial 20 that is capable of applying commands such as the frame-advance command and frame-back command continuously. A signal indicating degree of rotation output from the jog dial 20 also is input to the CPU 21 .

[0036] The digital still camera is provided with a liquid crystal display unit 16 . Camera angle or the like is decided by displaying the image of a subject on the display screen of the liquid crystal display unit 16 .

[0037] The digital still camera is capable of electronic flash photography and therefore includes a flash unit 1 and a flash driving circuit 2 for controlling the emission of light from the flash unit 1 .

[0038] The digital still camera is provided with a zoom lens 3 , diaphragm 5 and shutter 7 . The zoom lens 3 , diaphragm 5 and shutter 7 are controlled by a lens driving circuit 4 , diaphragm driving circuit 6 and shutter driving circuit 8 , respectively. The digital still camera includes a CCD 9 controlled by a CCD driving circuit 10 .

[0039] When the imaging mode (still-picture imaging mode or a memo imaging mode) is set, the image of the subject is formed on the photoreceptor surface of the CCD 9 and a video signal representing the image of the subject is input to an analog signal processing circuit 11 . The latter executes predetermined analog signal processing such as a gamma correction processing and white balance adjustment processing. The video signal output from the analog signal processing circuit 11 is converted to digital image data in an analog/digital converter circuit 12 , whence the digital image data is input to a digital signal processing circuit 13 . The latter executes predetermined digital signal processing such as generation of luminance data Y and color-difference data R-Y and B-Y. The image data output from the digital signal processing circuit 13 is applied to and stored temporarily in a memory 14 .

[0040] The image data is read out of the memory 14 and input to a signal processing circuit 15 for display purposes. The latter executes pixel downsampling processing so as to display images on the liquid crystal display unit 16 , as well as other signal processing. Image data that is output from the signal processing circuit 15 is applied to the liquid crystal display unit 16 , whereby the image obtained by imaging is displayed on the display screen of the liquid crystal display unit 16 .

[0041] If the shutter switch 19 is pressed, the image data that has been stored in the memory as described above is input to a compression/expansion circuit 17 . The latter performs data compression such as compression in accordance with the JPEG (Joint Photographic Experts Group) standard. The compressed image data is applied to and recorded on a memory card 22 .

[0042] When the playback mode is set, compressed image data that has been recorded on the memory card 22 is read and is then expanded by the compression/expansion circuit 17 . The expanded image data is applied to the memory 14 and in memory 14 temporarily. Image data that has been stored in the memory 14 is read and applied to the signal processing circuit 15 . The image represented by the image data that has been recorded on the memory card 22 is displayed on the display screen of the liquid crystal display unit 16 .

[0043] Thumbnail image data also has been recorded on the memory card 22 and thumbnail images can be displayed in at-a-glance form on the display screen of the liquid crystal display unit 16 in a manner described later. In a case where thumbnail image data has not been recorded on the memory card 22 , this data would be generated by the CPU 21 .

[0044] FIG. 2 illustrates the display screen of the liquid crystal display unit 16 .

[0045] In this embodiment, a main image display area 31 and an index image display area (thumbnail image display area strip) 40 appear on a display screen 30 when the playback mode is set by the mode setting switch.

[0046] The main image display area 31 is formed substantially over the entirety of the display screen 30 .

[0047] The index image display area 40 is formed below the display screen 30 and has a number of thumbnail image display areas 41 to 49 . The thumbnail image display areas 41 to 49 are of equal height but the widths thereof diminish with distance from the center thumbnail image display area 45 in the transverse direction. As a result, a greater number of thumbnail image display areas are included in comparison with a case where all of the thumbnail image display areas that constitute the index image display area 40 have a size the same as that of the center thumbnail image display area 45 . Accordingly, thumbnail images of a large number of frames can be displayed.

[0048] FIG. 3 illustrates the relationship between the image display areas of the index image display area 40 and thumbnail images displayed in these image display areas.

[0049] As set forth above, the thumbnail image display areas that make up the index image display area 40 become progressively smaller in width as distance from the center thumbnail image display area 45 increases in the transverse direction. In this embodiment, the full image of a thumbnail image i 5 of a single frame is displayed in the center thumbnail image display area 45 . As distance from the center thumbnail image display area 45 increases, however, the portions of the images displayed in the thumbnail image display areas become progressively smaller.

[0050] Positioning for display of images is performed in the thumbnail image display areas 41 to 44 on the left side of the center thumbnail image display area 45 in such a manner that the left-hand edges of the thumbnail images will agree with the left-hand edges of the thumbnail image display areas. Of the thumbnail images i 1 to i 4 , therefore, thumbnail image portions a 1 to a 4 the sizes whereof match the sizes of the thumbnail image display areas 41 to 44 , respectively, are displayed in these display areas. Positioning for display of images is performed in the thumbnail image display areas 46 to 49 on the right side of the center thumbnail image display area 45 in such a manner that the right-hand edges of the thumbnail images will agree with the right-hand edges of the thumbnail image display areas. Of the thumbnail images i 6 to i 9 , therefore, thumbnail image portions a 6 to a 9 the sizes whereof match the sizes of the thumbnail image display areas 46 to 49 , respectively, are displayed in these display areas.

[0051] FIG. 4 is a flowchart illustrating processing in the playback mode for displaying portions (or the entirety) of the above-described thumbnail images. FIGS. 5 to 9 illustrate examples of images displayed on the display screen of the liquid crystal display unit.

[0052] The processing shown in FIG. 4 starts in response to setting of the playback mode by the mode setting switch. First, an image to be displayed in the main image display area 31 is selected by the user employing the operating switches 18 (step 51 ). Image data representing the selected image is read out of the memory card 22 and is then applied to the liquid crystal display unit 16 in the manner described above. The selected image (main image) is displayed in the main image display area 31 being displayed on the display screen 30 of the liquid crystal display unit 16 (step 52 ).

[0053] Thumbnail image data representing four frames of thumbnail images i 1 to i 4 and four frames of thumbnail image i 6 to i 9 on left and right sides, respectively, of the main image being displayed in the main image display area 31 is read from the memory card 22 (step 53 ). The thumbnail image data that has been read is applied to the memory 14 , where the data is stored temporarily.

[0054] Among the thumbnail images represented by the read thumbnail image data, those far from the main image (if frame numbers have been assigned, those thumbnail images having frame numbers far from that of the main image) are displayed at both ends of the index image display area 40 (step 54 ). If this is the initial display presented in the index image display area 40 , then the thumbnail images i 1 and i 9 will be displayed at the left and right ends, respectively, of the index image display area 40 , as illustrated in FIG. 5 . Thumbnail images next closest to the main image after these displayed thumbnail images are displayed successively in the index image display area 40 (step 55 ). Such subsequent thumbnail images are displayed so as to overlap the neighboring thumbnail images already being displayed. The processing of step 55 is repeated until the thumbnail image that corresponds to the selected main image is displayed in the index image display area 40 (step 56 ).

[0055] More specifically, if the thumbnail images i 1 and i 9 are being displayed on the display screen 30 , as shown in FIG. 5 , the next thumbnail image i 2 is displayed in such a manner that the left-hand portion of the image overlaps the thumbnail image i 1 . Further, the next thumbnail image i 8 is displayed in such a manner that the right-hand portion of the image overlaps the thumbnail image i 9 . The thumbnail images i 3 and i 7 are displayed in similar fashion inwardly of the thumbnail images i 2 and i 8 , respectively, as depicted in FIG. 7 . The thumbnail images i 4 and i 6 are displayed inwardly of the thumbnail images i 3 and i 7 , respectively, as shown in FIG. 8 , and finally the thumbnail image i 5 corresponding to the selected main image is displayed at the center, as shown in FIG. 9 .

[0056] Thus, a large number of thumbnail images are displayed in the index image display area 40 . Thumbnail images of a large number of frames can be displayed even if the display screen 30 is small in size, as in the case of a digital still camera.

[0057] If the frame-advance button is pressed (“YES” at step 57 ), the image of the frame that follows the main image being displayed in the main image display area 31 is displayed in the main image display area 31 . Further, each thumbnail image being displayed in the index image display area 40 is shifted rightward by one thumbnail image display area (step 58 ). If the frame-advance button is pressed when the conditions are as shown in FIG. 9 , the image that corresponds to thumbnail image i 4 being displayed at the left of the center thumbnail image display area 45 will be displayed in the main image display area 31 . Further, the thumbnail images i 1 to i 9 being displayed in the thumbnail image display areas 41 to 49 will be displayed in the thumbnail image display areas 42 to 49 one display area to the right. The thumbnail image i 9 is no longer displayed and the thumbnail image that follows the thumbnail image i 1 is displayed in the thumbnail image display area 41 .

[0058] If the frame-back button is pressed (“NO” at step 57 , “YES” at step 59 ), the image of the frame that precedes the main image being displayed in the main image display area 31 will be displayed in the main image display area 31 . Further, each of the thumbnail images being displayed in the index image display area 40 is shifted leftward by one thumbnail image display area (step 60 ). If the frame-back button is pressed when the conditions are as shown in FIG. 9 , the image that corresponds to thumbnail image i 6 being displayed at the right of the center thumbnail image display area 45 will be displayed in the main image display area 31 . Further, the thumbnail images i 1 to i 9 being displayed in the thumbnail image display areas 41 to 49 will be displayed in the thumbnail image display areas 41 to 48 one display area to the left. The thumbnail image i 1 is no longer displayed and the thumbnail image that follows the thumbnail image i 9 is displayed in the thumbnail image display area 49 .

[0059] FIGS. 10 to 12 illustrate a modification of the above embodiment.

[0060] FIG. 10 is a diagram illustrating the relationship between the image display areas of the index image display area 40 and thumbnail images displayed in these image display areas.

[0061] Positioning for display of images is performed in the thumbnail image display areas 41 to 44 and 46 to 49 (namely thumbnail image display areas from which the center thumbnail image display area 45 has been excluded) in such a manner that the central portions of the thumbnail images will coincide with the central portions of the thumbnail image display areas. Of the thumbnail images i 1 to i 4 and i 6 to i 9 , therefore, thumbnail image portions a 11 to a 14 and a 16 to a 19 the sizes whereof match the sizes of the thumbnail image display areas 41 to 44 and 46 to 49 , respectively, are displayed in these display areas.

[0062] The portion of an image that is important is considered to be located at the center of the image. In this modification, the central portion of a thumbnail image is displayed and therefore the approximate nature of the image can be grasped.

[0063] FIG. 11 is a flowchart illustrating processing in the playback mode for displaying the central portions (or the entirety) of the above-described thumbnail images. Processing steps in FIG. 11 identical with those of FIG. 4 are designated by like step numbers and need not be described again. FIG. 12 is a diagram illustrating examples of images displayed on the display screen of the liquid crystal unit.

[0064] The processing shown in FIG. 11 , besides be devoid of the processing of steps 55 and 56 shown in FIG. 4 , has the processing indicated by step 54 A instead of the processing indicated by step 54 .

[0065] When thumbnail image data is read from the memory card 22 (step 53 ), the images of the central portions set beforehand from among the thumbnail images are displayed in the corresponding thumbnail image display areas 41 to 49 (step 54 A). As shown in FIG. 12 , image portions all to a 19 at the central portions of the thumbnail images i 1 to i 9 are displayed in the thumbnail image display areas 41 to 49 , respectively, constituting the index image display area 40 .

[0066] Even though the portions making up both sides of an image are not displayed, the central image portion is displayed. This makes it possible grasp the general nature of the image.

[0067] FIGS. 13 to 15 illustrate a second modification of the above embodiment.

[0068] FIG. 13 is a diagram illustrating the relationship between the image display areas of the index image display area 40 and thumbnail images displayed in these image display areas.

[0069] The thumbnail images i 1 to i 4 and i 6 to i 9 displayed in the thumbnail image display areas 41 to 44 and 46 to 49 (namely thumbnail image display areas from which the center thumbnail image display area 45 has been excluded) are reduced in size in such a manner that they will agree with the transverse widths of the thumbnail image display areas 41 to 44 and 46 to 49 , respectively. The processing for performing this size reduction can be implemented by downsampling in the transverse direction.

[0070] This modification makes it possible to grasp the entirety of each thumbnail image.

[0071] FIG. 14 is a flowchart illustrating processing in the playback mode for displaying the above-described thumbnail images. Processing steps in FIG. 14 identical with those of FIG. 4 are designated by like step numbers and need not be described again. FIG. 15 is a diagram illustrating examples of images displayed on the display screen of the liquid crystal unit.

[0072] The processing shown in FIG. 14 has processing indicated by steps 61 and 62 instead of the processing indicated by steps 54 and 55 in FIG. 4 .

[0073] When thumbnail image data is read from the memory card 22 (step 53 ), processing for size reduction in the transverse direction is executed in such a manner that the widths of the thumbnail images i 1 to i 4 and i 6 to i 9 will take on the widths of the corresponding thumbnail image display areas 41 to 44 and 46 to 49 , respectively (step 61 ). As shown in FIG. 15 , the reduced-size thumbnail images i 1 to i 4 and i 6 to i 9 are displayed in the corresponding thumbnail image display areas 41 to 44 and 46 to 49 (step 62 ). The thumbnail image i 5 , which has not undergone the transverse-direction size reduction, is displayed in the center thumbnail image display area 45 .

[0074] Thus, the entire images can be ascertained.

[0075] FIGS. 16 and 17 illustrate a third modification of the above embodiment.

[0076] FIG. 16 is a diagram illustrating examples of images displayed on the display screen.

[0077] As shown in FIG. 16, a main image display area 31 A is displayed at the center of the display screen 30 . An index image display area 40 A is displayed so as to encircle the lower part of the main image display area 31 A.

[0078] The index image display area 40 A has the shape of a cylinder, which has a prescribed height, when looked down upon obliquely from above.

[0079] Since the index image display area 40 A is construed as being a cylinder, it has an outer circumferential surface and an inner circumferential surface. The index image display area 40 A is formed to have a plurality of thumbnail image display areas 73 to 77 on the outer circumferential surface on the side in front of the main image display area 31 A and a plurality of thumbnail image display areas 71 , 72 , 78 and 79 on the inner circumferential surface on the side in back of the main image display area 31 A. Displayed in these thumbnail image display areas are the corresponding thumbnail images i 1 to i 9 . A thumbnail image that corresponds to the main image being displayed in the main image display area 31 A is displayed in a center thumbnail image display area 75 on the outer circumferential surface on the side in front.

[0080] As will be described later, each thumbnail image to be displayed in thumbnail image display areas 73 to 77 , 71 , 72 , 78 and 79 of the index image display area 40 A is caused to be displayed in the neighboring thumbnail image display area on the left or right side in response to application of a frame-advance command or frame-back command.

[0081] FIG. 17 is a flowchart illustrating processing in the playback mode. Processing steps in FIG. 17 identical with those of FIG. 4 are designated by like step numbers and need not be described again.

[0082] The processing shown in FIG. 17 has processing indicated by steps 54 A and 55 A instead of the processing indicated by steps 54 and 55 in FIG. 4 .

[0083] When thumbnail image data is read from the memory card 22 (step 53 ), the thumbnail image corresponding to the main image being displayed in the main image display area 31 A is displayed in the center thumbnail image display area 75 . Thumbnail image data is processed in such a manner that the corresponding thumbnail image is deformed in accordance with distance from the center thumbnail image display area 75 (distance along the circumference) (step 54 A). The deformed thumbnail images are displayed in the thumbnail image display areas in order of decreasing distance from the center thumbnail image display area 75 (step 55 A). This control for displaying thumbnail images is repeated until the thumbnail image that corresponds to the main image display area 31 A is displayed in the center thumbnail image display area 75 (step 56 ).

[0084] The image displayed in the main image display area 31 A changes, and each thumbnail image displayed in the index image display area 40 A is caused to be displayed in a thumbnail image display area on the left or right side, in accordance with whether the frame-advance button or frame-back button is pressed. This is as set forth above.

[0085] In the above-described embodiment, the main image being displayed in the main image display area 31 A ( 30 ) changes, and so do the thumbnail images displayed in the index image display area 40 A ( 30 ), in response to depression of the frame-advance button or frame-back button. However the jog dial 20 can also be utilized, as mentioned above. In dependence upon the direction in which the jog dial 20 is turned, frames are moved ahead or back by an amount corresponding to the angle through which the jog dial 20 is turned. Thumbnail images corresponding to the angle of rotation of the jog dial 20 are displayed in the thumbnail image display areas and the main image is displayed in the main image display area.

[0086] As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.