Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1989-09-21
1991-05-07
Kostak, Victor R.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358447, 358455, 382 54, 340793, H04N 514
Patent
active
050141295
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a video signal processing apparatus for converting an input analog video signal including a variable-density image signal and a two-state image signal into an output analog video signal with the number of scanning lines increased.
BACKGROUND ART
When displaying an image represented by an input analog video signal by the use of a cathode ray tube (hereinafter referred to as a CRT) or the like having a large number of scanning lines in an enlarged or high-definition mode, generally, the input video signal is converted by an A-D converter into a digital signal, the digital data corresponding to one frame is stored in a first frame memory, the data held in this frame memory is converted by an enlarge interpolator into an enlarged image data signal and written in a second frame memory, and then the image data held in this second frame memory is successively read out and converted by a D-A converter into an analog signal, this analog signal output being used in displaying the original image in the enlarged or high-definition mode. When converting the original image data made up of 512.times.512 pixels into the enlarged image data made up of 1024.times.1024 pixels, the enlarge interpolator is designed to interpolate, between adjacent original pixels, a new pixel having such an intensity level as to linearly interpolate the intensity levels of these adjacent original pixels.
However, if such an interpolation processing is adopted in handling the image data on which a so-called two-state image is overlaid, for example, a variable-density image on which another image of character, graphic symbol, cursor, etc. is displayed in superposed form, the interpolation processing is performed in the surroundings of each overlay pixel, or between the overlay pixel having a high intensity level and each pixel of the variable-density image generally having a lower intensity level than the former; as a result, a new pixel having an intermediate intensity level between them is interpolated. Therefore, if the thus interpolated enlarged image data is displayed, the surroundings of the overlay image grow dim, spoiling the sharpness of a display of character, graphic symbol, cursor, etc.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a video signal processing apparatus for converting an input analog video signal including a variable-density image signal and a two-state image signal into an output video signal with the number of scanning lines increased without spoiling the visibility of a two-state image display.
In brief, the present invention processes an input video signal by; separating the input video signal into variable-density image data and two-state image data, replacing a portion of the variable-density image data from which the two-state image data is removed with a variable-density image data portion immediately before the beginning of the two-state image data, storing the variable-density image data and the two-state image data separately in memory means, performing a general analog-mode enlarge interpolation processing such as a linear interpolation processing on the variable-density image data, performing a two-state-mode enlarge interpolation processing on the two-state image data, and re-combining the variable-density image data and the two-state image data both enlarge-interpolated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an embodiment of the present invention;
FIG. 2 is a diagram showing exemplary input analog video signal and composite synchronizing signal;
FIG. 3 is a diagram showing the relationship between the input analog video signal, and two-state image data and variable-density image data separated from the former;
FIGS. 4A and 4B are diagrams explanatory of an enlarge interpolation processing for the variable-density image data; and
FIGS. 5A and 5B are diagrams explanatory of another enlarge interpolation processing for the two-state image data.
BEST MODE FOR CARRYING OUT THE INVENTION
An emb
REFERENCES:
patent: 4251837 (1981-02-01), Janeway, III
patent: 4924521 (1990-05-01), Dinan et al.
Kojima Moonray
Kostak Victor R.
Yokogawa Medical Systems Limited
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