Computer graphics processing and selective visual display system – Display peripheral interface input device – Light pen for fluid matrix display panel
Patent
1996-01-19
2000-04-25
Shalwala, Bipin
Computer graphics processing and selective visual display system
Display peripheral interface input device
Light pen for fluid matrix display panel
348443, 348458, 348459, 348430, H04N 520
Patent
active
060549777
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the processing of video signals to provide improved displays.
It has previously been recognised that the appearance of television displays can be improved by increasing the number of fields displayed in a given time. This is particularly beneficial for displays which are larger or brighter than average because the flicker arising from normal 50 Hz (or 60 Hz in NTSC) field rates becomes more noticeable. Specifically, the eye is more sensitive to motion of bright objects in peripheral vision.
Several techniques have been proposed for doubling display field rates. In one approach, each field is displayed at two vertically offset positions. This has, however, the disadvantage that finely detailed horizontal features in the picture appear to hop up and down at the original field rate because of this vertical displacement. Also, movement in the picture becomes less smooth so that moving objects appear to judder.
In one previous attempt to reduce these difficulties, two extra fields are interposed, one after and one before alternate input fields. The resulting sequence is re-timed to give an equal time interval between the start of successive fields. Each extra field is interpolated from the adjacent original field and is vertically offset from the original fields by half a line pitch. This approach produces a picture which does not hop but there is a variation in the sharpness of finely detailed horizontal features between the original fields and the interpolated fields, which makes such features appear to twitter. The approach still suffers from motion judder.
In another prior proposal--which attempts to overcome the problem of twitter--two new fields are interpolated from every original field, offset respectively up and down one quarter of a line pitch from that original field. This reduces hop and twitter but still suffers from the disadvantages of judder and reduced vertical resolution.
It is an object of the present invention to provide an improved method of video display conversion, which provides an increased rate of field display with less problems of judder, hop, twitter and lost vertical resolution.
Accordingly, the present invention consists in a method of video display conversion which increases the rate of field display, wherein every output field from the conversion is interpolated taking information from two or more input fields.
It has been recognised in the present invention that by taking information from more than one original field to create each output field, it is possible to reduce judder significantly and at the same time to improve the vertical resolution over known approaches. It is also possible to avoid variations in vertical resolution from one output field to the other and--consequently--to remove objectionable twitter from the displayed picture.
The present invention will now be described by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a diagram illustrating a method in accordance with the present invention in which output fields are derived in a video display conversion, doubling the field rate;
FIG. 2 is a diagram similar to FIG. 1, but introducing a new notation;
FIG. 3 is a diagram similar to FIG. 2, illustrating a modification;
FIG. 4 is a diagram similar to FIGS. 2 & 3 (with arrowed lines omitted for the sake of clarity) illustrating a further modification;
FIG. 5 is a diagram illustrating a method in accordance with a further embodiment of the present invention in which output fields are derived in a video display conversion which increases the field rate by one-and-a-half times;
FIG. 6 is a diagram similar to FIG. 5, illustrating a further modification; and
FIG. 7 is a block diagram illustrating apparatus in accordance with the present invention.
Referring initially to FIG. 1, a line in the original or input field sequence is marked "+" and a line in the interpolated or output field sequence marked ".largecircle.". Arrows extending between input lines + and output lines .largecircle. indicate contributions from t
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Longcroft Simon
Owen Chris
Weston Martin
Kinberg Robert
Kovalick Vincent E.
Shalwala Bipin
Snell & Wilcox Limited
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