This patent application is assigned to Canon Kabushiki Kaisha.
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to an imaging apparatus that records moving images, and to a reproducing apparatus that reproduces the moving images, such as a video camera or a digital camera.
"In recent years, a recording and reproducing apparatus capable of recording/reproducing high-quality video signals such as high definition (HD) video signals or HD signals, and a video display apparatus capable of displaying such signals as images have been widely spread. Background techniques of an image processing system used in these apparatuses include techniques of miniaturizing the size of an image sensor, increasing the number of pixels, increasing the speed of transfer processing, and improving the efficiency of coding such as the H.264 standard. In addition, various types of video display apparatuses have been made available, such as those of a liquid crystal type, a plasma type, and an electro-luminous (EL) type. Further, video display apparatuses having a further decreased thickness, a higher definition, and/or a larger screen are being developed. Mobile-type video display apparatuses are also being developed.
"Since display apparatuses of such various types have been become available, users' viewing styles have changed significantly. Users handle images in various manners depending on the purpose, for example, some users prefer high-quality images while others wish to exchange short movies with ease.
"Techniques for storing large amounts of video data play an important role in addressing the needs of users. Particularly, remarkable progress has been made in the increase of the capacity of hard disks and in the decrease of costs thereof, followed by semiconductor memories. Additionally, large-capacity removable media or servers on the order of terabytes have been made available at low cost.
"Under the background described above, while the frame rate of the national television system committee (NTSC) is 29.97 frames/second in the field of imaging techniques, higher frame rates such as 120 frames/second and 240 frames/second are proposed. Further, techniques for multi-screen reproduction and reproduction with multi-audio channels are also being developed. Based on these techniques, more realistic and dynamic images can be displayed.
"While video signals are conventionally recorded at a fixed frame rate, some techniques are proposed for appropriately changing the frame rate, efficiently suppressing the total amount of recording data, and recording high-quality videos when necessary.
"Japanese Patent Application Laid-Open No. 2003-274360 (U.S. Pat. No. 7,456,875) discusses a technique for controlling the frame rate of captured video signals without requiring a photographer's control. More specifically, based on this technique, when an image is captured, a surrounding audio volume level is monitored, and if it is detected that the monitored volume level exceeds a predetermined level, the frame rate is increased, so that important scenes are recorded with high quality. Further, based on this technique, when the available memory capacity of a recording medium reaches less than or equal to a predetermined level, the frame rate is decreased to suppress consumption of the recording medium. In addition, when the available power of a battery reaches less than or equal to a predetermined level, the frame rate is decreased to suppress consumption of the battery.
"Japanese Patent Application Laid-Open No. 2007-134991 (USPA 2007/0104462) discusses a technique in which motion of a captured image is detected. Based on this technique, when the detected motion is more than or equal to a threshold, the captured image is recorded at a high frame rate, and when the detected motion is less than the threshold, the captured image is recorded at a low frame rate.
"However, based on the above techniques discussed in Japanese Patent Application Laid-Open No. 2003-274360 (U.S. Pat. No. 7,456,875) and Japanese Patent Application Laid-Open No. 2007-134991 (USPA 2007/0104462), change of the frame rate does not reflect photographer's intention. Namely, based on the technique discussed in Japanese Patent Application Laid-Open No. 2003-274360 (U.S. Pat. No. 7,456,875), the frame rate is changed depending on conditions surrounding an imaging apparatus, such as the surrounding audio volume level or the available power of a recording medium or a battery. Thus, the imaging condition is changed without photographer's intention.
"In addition, the technique discussed in Japanese Patent Application Laid-Open No. 2007-134991 (USPA 2007/0104462) uses motion information acquired from an image signal as an index. For example, when the ratio of monotonous scenes including the sky or night scenes is increased, it is determined that the amount of motion is less, and as a result, the image is recorded at a low frame rate. On the other hand, in a wide image whose focal length is short, the motion amount tends to be detected as being large because of camera shake, and consequently, the image is recorded at a high frame rate. In either case, the frame rate is determined irrespective of photographer's intention.
"Normally, TV receivers or video monitors support only a fixed frame rate. Thus, when a video signal is input and the frame rate thereof is changed in the middle of processing, even if the change of the frame rate can be followed, the video may be displayed at an unnatural rendering speed misaligned with the actual time. For example, if a monitor receives an input video signal and displays the signal at a certain rate images captured at a frame rate higher than the standard frame rate are rendered in slow motion, and images captured at a lower frame rate are rendered at high speed.
"Since compatibility between these viewing and reproduction environments is not taken into consideration, use of the technique of variable frame rate recording is limited."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventor's summary information for this patent application: "The present invention is directed to an imaging apparatus capable of changing a frame rate in view of a photographer's intention and maintaining compatibility with existing viewing and reproduction environments.
"According to an aspect of the present invention, an imaging apparatus includes an imaging unit including an image sensor configured to convert an optical image to an image signal, and a zoom unit configured to optically zoom an optical image incident on the image sensor or electronically zoom an image signal output from the image sensor, a recording unit configured to record a video signal including an image signal captured by the imaging unit in a recording medium, and configured to record a recording frame rate, at which the video signal is recorded in the recording medium, and zoom operation information for the zoom unit in the recording medium, a zoom operation unit configured to operate the zoom unit, a control unit configured to control the recording frame rate at which the video signal is recorded in the recording medium based on an operation of the zoom operation unit, and configured to increase the recording frame rate to be higher than a normal frame rate during a period including a period when the zoom operation unit is operated, and a reproducing unit configured to reproduce the video signal from the recording medium based on a set reproduction mode, and configured to carry out thinning processing on the video signal during the period including the period when the zoom operation unit is operated based on the zoom operation information and reproduce the processed video signal at the normal frame rate.
"Based on an imaging apparatus and a reproducing apparatus according to the present invention, videos including zoom operations can be reproduced. Since videos are reproduced at a standard frame rate, compatibility with existing video display apparatuses can be ensured. During periods including zoom operation periods, videos are recorded at a frame rate higher than a normal frame rate, and when the videos are reproduced, the frame rate is reduced to the standard frame rate. Thus, high-quality reproduction videos can be displayed.
"Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
"The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention.
"FIG. 1 is a block diagram illustrating a schematic configuration of an exemplary embodiment of the present invention.
"FIGS. 2A to 2C illustrate a relationship among a zoom operation, captured frames, and recorded frames of the exemplary embodiment.
"FIG. 3 is a flow chart illustrating a recording operation of the exemplary embodiment.
"FIG. 4 illustrates a relationship between a zoom speed and a recording frame rate of the exemplary embodiment.
"FIG. 5 illustrates a metadata structure and data examples of the present exemplary embodiment.
"FIG. 6 illustrates a relationship between zoom magnification and recorded frames of the exemplary embodiment.
"FIG. 7 illustrates recording areas each storing frames at different frame rates.
"FIG. 8 is a flow chart illustrating a reproduction operation of the exemplary embodiment.
"FIG. 9 is a table illustrating reproduction modes that involve zoom operations.
"FIG. 10 illustrates frame interpolation in reproduction mode 1 of the exemplary embodiment.
"FIG. 11 illustrates frame interpolation in reproduction mode 2 of the exemplary embodiment.
"FIG. 12 illustrates frame interpolation in reproduction mode 3 of the exemplary embodiment.
"FIG. 13 illustrates frame interpolation in reproduction mode 5 of the exemplary embodiment.
"FIG. 14 is a block diagram illustrating functions of a system control unit 50.
"FIGS. 15A to 15D illustrate a relationship among a zoom operation, captured frames, and recorded frames of a second exemplary embodiment.
"FIG. 16 illustrates a relationship between zoom magnification and recorded frames of the second exemplary embodiment."
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