Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1990-04-30
1991-10-01
Kostak, Victor R.
Facsimile and static presentation processing
Facsimile
Recording apparatus
358105, 358126, H04N 718
Patent
active
050538764
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns image stabilisation particularly, but not exclusively, the stabilisation of TV camera images.
Many circumstances arise in which the quality of video data is impaired. For example, a TV camera may suffer from unstable pointing if the camera is hand-held, or is rigidly mounted on a moving platform, for example, a vehicle such as a vessel or aircraft. The problem is aggravated if a long focal length lens is used to form the image. Generally, it is not possible to repeat the data gathering exercise if it is subsequently found that the data, e.g. on a video recording, is impaired in this way.
DESCRIPTION OF RELATED ART
The conventional solution of this problem is to increase the inertia of the sensor so as naturally to dampen any motion of the sensor (for example, electronic news gathering cameras) due to hand pointing. This solution does not guarantee stability if the data is acquired from a moving platform. A better solution, albeit more expensive, relies on inertially stabilising the camera by mounting the latter on a gyroscopically stabilised platform e.g. a "STEADY SCOPE" (trade mark) mounting platform. Devices of this type have been widely used in aerial surveillance but possess certain disadvantages. If the camera is directed at a moving object and panned to follow the object, the gyroscopes precess and the resultant video image is no longer centred on the object of interest. Further, the time response of the mounting platform will not necessarily be tuned to the pointing fluctuations of the camera. Neither of the present solutions enable correction of already generated video data, for example, that recorded on video tape.
It is an object of the present invention to provide a method and apparatus wherein the aforesaid disadvantages are overcome.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an electronic image stabilisation apparatus comprising converter means for digitising a video signal to be stabilised, a framestore for storing digital information relating to at least two frames, window defining means, means for identifying at least one specific pixel within the or each window, means for comparing the location of the or each pixel in succeeding frames and for remapping the frame to cancel a detected movement vector.
The invention also provides a method of electronic image stabilisation comprising the steps of digitising an analogue video signal into pixels, defining within each frame at least one window, storing the value and location of at least one pixel within the or each window of a first frame, comparing the position of the at least one pixel in a next succeeding frame with the stored value, and remapping the frame to cancel a vector defining detected movement between the pixel location.
The invention will be described further, by way of example, with reference to accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block schematic diagram of a stabilisation unit according to the present invention; and
FIG. 2 is an illustration of a video frame diagrammatically indicating electronic image stabilisation in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, an electronic image sensor 10 comprises a video camera 12 having a lens 14. The camera may be connected in known manner to a video recorder 16 or 16a and to a monitor 18. The camera may be hand held and, consequently, subject to pointing instability.
In accordance with the present invention, the video data derived from the camera 12 (or subsequently from the recorder 16) is electronically stabilised. To this end, the video data from the camera 12, in real time, or from the recorder 16 is passed to an image processor 20. The image processor 20 comprises an analogue-to-digital-converter (ADC) and a digital-to analogue-converter (DAC) module 22 which serves to convert incoming video data to digital form. The resolution of the ADC may be 8, 12 or more bits depending upon the s
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patent: 4612575 (1986-09-01), Ishman et al.
patent: 4692806 (1987-09-01), Anderson et al.
patent: 4709264 (1987-11-01), Tamura et al.
patent: 4823194 (1989-04-01), Mishima et al.
"A New Technique to Improve Video Stability by Digital Processing"; SMPTE Journal, vol. 97, #11; Nov. '88; Matsuzuru et al.
129th SMPTE Technical Conference in L.A., Nov. '87; Matsuzuru et al.
Blissett Rodney J.
Collar Martin
Kostak Victor R.
Roke Manor Research Limited
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