Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1989-05-25
1990-07-17
Groody, James J.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 14, 358 22, 358 13, H04N 1106
Patent
active
049424572
DESCRIPTION:
BRIEF SUMMARY
This invention relates to circuitry for processing video signal components.
BACKGROUND OF THE INVENTION
It is know from the journal "Funkschau", volume 25, page 53, 1985, to process and reproduce a composite video signal digitally. In this system the composite video signal is converted to digital form in an analog-to-digital converter and then split into the components of the luminance signal Y and the chrominance components U and V in a digital color decoder. In order to avoid an excessive number of connections the signals are transmitted in time multiplexed fashion and subsequently stored in picture memories.
In picture-in-picture systems wherein images from one video source are to be displayed within images from another video source, the video signals from the first source are typically split into components parts and then applied to analog-to-digital converters. Desirably only a single analog-to-digital converter is used by multiplexing the analog video components thereto. However, problems arise in multiplexing the components to a single converter. For example the analog-to-digital converter must operate at a high sampling rate in order to produce a picture of acceptable resolution.
There are several solutions to appropriately multiplexing the component video signals to a single converter. For example, the analog video component signals may be sampled and multiplexed to form horizontal lines of signal in the form of YUYV sampled data where Y is the luminance signal and U and V are the chrominance signal parts (U=B-Y, V=R-Y). These sequences of sampled data are applied to the analog-to-digital converter which generates their digital counterparts. The digital values are written to memory at a first frequency rate, and read out at a higher frequency rate to achieve horizontal compression of the image. For vertical compression only one out of every set of three or four horizontal lines of the video input signal is analyzed. The reduction ratio is selected dependent on the desired result. If necessary, the signal is applied to a vertical filter.
The signal read from memory is applied to three digital-to-analog converters to reproduce the compressed Y, U and V signals. Subsequently, the compressed signals are substituted for portions of the main video signal.
The concepts developed to date provide picture-in-picture processing for TV signals requiring a reduced number of circuit connections. However, a relatively high multiplexing frequency is used in order to obtain a correct signal bandwidth for each video component.
It is an object of the present invention to provide a circuit for processing a picture-in-picture video signal at reduced cost.
SUMMARY OF THE INVENTION
The present invention provides for subsampling the input video signal in order to reduce the amount of data to be processed. Subsampling results in the loss of picture information to be displayed, however this loss of information is acceptable because the size of the reproduced image is reduced. For example, the inset image may be reduced to a quarter of its original size. In processing the video signal the luminance and color difference components may be selected. Both parts of the signal (luminance and chrominance) may be applied to the same horizontal filter structure and a single analog-to-digital converter.
In the present invention, separated chrominance components (U, V) are coupled to a first multiplexer which alternately selects the respective chrominance components at a rate of F.sub.H /N, where F.sub.H is the horizontal line frequency and N is an integer greater than 2. The output of the first multiplexer and the luminance component are coupled to respective signal input terminals of a second multiplexer. The second multiplexer is conditioned to alternately provide the luminance and chrominance components at one half the vertical frequency. That is, the second multiplexer provides fields of luminance samples alternating with fields of chrominance samples.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of video
REFERENCES:
patent: 4163248 (1979-07-01), Heitmann
patent: 4821086 (1989-04-01), McNeely et al.
Service Manual, Panasonic VHS, PV-4768/PV-4768-K, Order No. VRD8704307 B3, pp. 2-1-25, 2-1-26.
Keesen Heinz-Werner
Perdrieau Laurent
Deutsche Thomson-Brandt GmbH
Groody James J.
Harvey David E.
Hayes James B.
Herrmann Eric P.
LandOfFree
Circuit arrangement for processing video components does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit arrangement for processing video components, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit arrangement for processing video components will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-98110