Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1991-04-05
1993-01-19
Groody, James J.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358209, H04N 700
Patent
active
051811022
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates principally to a camera and to a visual display device.
For high-definition television, an HDQ model has been proposed for a quincuncial sequential mode. Such a mode is used both when taking pictures and upon display on cathode-ray tubes. Furthermore, all the devices operated at very high sampling frequency, for example 144 MHz; and this makes their construction difficult and their prime cost high.
In "Digest of Technical Papers" of International Conference on Consumer Electronics, June 1988, Chicago, page 60 in the article "Wide Dynamic HDTV Image Sensor with Alias Suppression", there is proposed a charge transfer sensor having a vertical quincuncial structure. The quincuncial structure relates only to the photosensitive cells and not to the spatial distribution actually sampled at the output. At each clock cycle, the signals from four elemental cells are summated to form a signal corresponding to that of a cell of larger size permitting the suppression of defects of the image.
The use of optical filters placed in front of charge transfer sensors (CCD in English-language terminology) has been proposed for the purpose of eliminating the high spatial frequencies producing folding of the spectrum beyond the half-frequency corresponding to the pitch of the sensor.
An object of the invention is digital television associating quincuncial scanning and subsampling. In order to avoid any folding of the spectrum due to the subsampling, the optical filtering of the signal is carried out. The optical filter reduces the resolution. Advantageously, the reduction of the resolution is carried out diagonally. In fact, the diminution of the resolution along the diagonals of the image causes little trouble, since it is difficult for humans to perceive this.
A further object of the invention is to provide devices for taking pictures and for visual display which are specially suitable for this type of quincuncial scanning.
SUMMARY OF THE INVENTION
According to an aspect of the invention there is a digital device for acquisition or for display of television images, having a plurality of quincuncial lines operating in subsampling mode, with an optical filter for reducing the diagonal resolution.
The display may be a television, with a cathode-ray tube, or a flat liquid crystal screen.
The device for taking pictures is a television camera, with a vacuum tube, sensor or a CCD charge transfer sensor.
The optical filter may have birefringent optical plates which are parallel to one another, and optical means forming the Fourier transform of the image, and a diaphragm eliminating high diagonal spatial frequencies from the spectrum.
A further aspect of the invention is a charge transfer device (CCD) with a plurality of photosensitive cells and shift registers, in which the successive cells and their associated registers are disposed in quincunx.
A further aspect of the invention is a display device with a plurality of display cells, in which the successive cells are disposed in quincunx. The cells have the shape of a characterised in that the cells have the shape of a lozenge, one half of the width of which is proportional to 1/P, P being the number of points in one line of an image obtained by said device. Alternatively, the cells have the shape of a lozenge, one half of the height of which is proportional to 1/N, N being the number of useful lines of an image obtained by said device.
The device has the capacity to provide a visual display of colours; and it may be liquid crystals (LCD) or plasma panel, or Cathode-ray tube (CRT).
Each cell 1, 1 to N, P has a plurality of elements (R, G, B) which are capable of displaying different colours, the elements of each colour being disposed in quincunx. The elements (R, G, B) are disposed in columns with a cyclic distribution of the colours, the successive columns being offset by 0.5 times the pitch of the triplet (R, G, or B) of colours.
The invention will be better understood by means of the description hereinbelow and the accompanying
REFERENCES:
patent: 3588224 (1971-06-01), Pritchard
patent: 4587553 (1986-05-01), Wantanabe et al.
patent: 4675727 (1987-06-01), Sekizawa et al.
patent: 4761682 (1988-08-01), Asaida
patent: 4807981 (1989-02-01), Takizawa et al.
patent: 4988171 (1991-01-01), Yokota
IEEE Transactions on Consumer Electronics vol. 34, No. 3; Nishida et al. "Wide Dynamic range HDTV Image Sensor With Aliasing Suppression", Aug. 1988.
FKT Fernsen-Und Kino-Technik, vol. 42, No. 10, Oct. 1988 Silverberg: "HQTV-Systeme-Ein Vergleich
Groody James J.
Plottel Roland
Powell Mark R.
Thomson Consumer Electronics
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