A variety of methods of displaying a three-dimensional image have conventionally been proposed. Among those methods, a “two-viewpoint system” utilizing binocular parallax has commonly been used. That is, stereoscopic vision is obtained by preparing an image for left eye and an image for right eye having binocular parallax therebetween and projecting the respective images to right and left eyes independently.
FIG. 41 is a conceptual illustration of a “time-division scheme” which is one representative of the two-viewpoint system.
In the time-division scheme, the image for left eye and the image for right eye are alternately arranged in a top-to-bottom direction as shown in FIG. 41, and a field displaying the image for left eye and a field displaying the image for right eye are alternately switched for display. Here, vertical resolution of the image for left eye and the image for right eye is half the vertical resolution of normal two-dimensional display. An observer wears shutter-type glasses in which a shutter opens and shuts in synchronization with a switching cycle of the display. As to the shutter used herein, the left eye side opens and the right eye side shuts while the image for left eye is displayed, whereas the left eye side shuts and the right eye side opens while the image for right eye is displayed. In this manner, the image for left eye is observed only with the left eye and the image for right eye is observed only with the right eye, thereby obtaining stereoscopic vision.
FIGS. 42A and 42B are conceptual illustrations of a “parallax barrier scheme” which is another representative of the two-viewpoint system.
FIG. 42A shows a principle to produce parallax, while FIG. 42B shows a screen displayed in accordance with the parallax barrier scheme.
An image including paired images for left eye and right eye arranged in stripes as shown in FIG. 42B is displayed on an image display panel 91 as shown in FIG. 42A. Then, what is called a parallax barrier 92 having slits at intervals corresponding to the images is placed in front of the image display panel. Here, stereoscopic vision is obtained by observing the image for left eye only with left eye 93 and the image for right eye only with right eye 94.
Japanese Patent Laying-Open No. 11-41627 discloses one example of a data recording format used for three-dimensional display in accordance with a lenticular scheme based on a principle the same as that of the parallax barrier scheme.
FIGS. 43A to 43C are conceptual illustrations showing one example of such a data recording format in accordance with the “lenticular scheme.”
Specifically, images for left eye 101 shown in FIG. 43A and images for right eye 102 shown in FIG. 43B are sub-sampled respectively so as to prepare one mixed image 103 shown in FIG. 43C for recording. In reproduction, mixed image 103 is re-arranged so as to create a combined image as shown in FIG. 42B.
In addition to the example of the two-viewpoint system described above, there are various methods for displaying a three-dimensional image. Here, however, recorded data generally lacks compatibility among different display schemes.
For example, the data recorded so as to adapt to the time-division scheme cannot be displayed as it is on a three-dimensional display adapted to the parallax barrier scheme. Therefore, in a conventional three-dimensional display system, data is recorded on the assumption that a display method is initially fixed, without taking into account versatility of the recorded data. For example, if it is decided that a three-dimensional display adapted to the parallax barrier scheme is used, data intended to be shown on that display is recorded on a recording medium. Here, since a possibility of being shown on a display adapted to another scheme is not considered, information that the recorded data is available for the parallax barrier scheme is not recorded on a file.
There are various types of information necessary for three-dimensional display, such as the number of viewpoints or a method of sub-sampling, in addition to the display scheme. Such information, however, is not recorded on the file either because the display scheme has been fixed to one. In other words, if the same scheme is always used, it is not necessary to record such information. On the other hand, this fact remarkably impairs versatility of the recorded data. For example, as far as data adapted to the parallax barrier scheme (or the lenticular scheme) is recorded, the image for left eye and the image for right eye can be recorded as separate sequences, or alternatively, a mixed image in which the image for left eye and the image for right eye are arranged side by side so as to each occupy half an area of the screen as shown in FIG. 43C can be recorded. Alternatively, a combined image in which paired images for left eye and right eye are arranged in stripes as shown in FIG. 42B can be recorded. If a recording format is different, a processing method for subsequent display will naturally be different. It is impossible, however, to know in which format the data has been recorded, from the recorded data. Therefore, when a third party obtains the data, he/she does not know what kind of processing should be adopted for displaying the data.