GB2252000A - Television display pan vector control - Google Patents

Abstract

When wide screen television signals are viewed on a standard format display, the displayed area may be selected automatically according to a pan vector transmitted with the signals, or manually via a remote control. The time taken to switch between the two modes using a menu may mean that the scene of interest is missed; therefore it is arranged that the remote control takes priority as soon as it is operated, i.e to commence panning to left or right, and a predetermined time after the last operation of the control there is a smooth transition back to the automatically selected area. The system may also be applied to vertical area selection or zooming. <IMAGE>

Description

Television Pan Vector Control The present invention relates to a pan vector control in television receivers.

Background Many of present day TV receivers have a nominally 4:3 aspect ratio display.

According to a specification of the MAC TV signal transmission system this kind of TV signal can be transmitted either in a 16:9 or in a 4:3 aspect ratio. In order to display 16:9 TV signals on standard 4:3 receivers as shown in Fig. 1A, pan vectors which are transmitted together with the MAC signal may be evaluated.

There are satellite receivers, such as the Ferguson SRB1 BSB receiver, which are able to decode 16:9 TV signals and to evaluate transmitted pan vectors. For the use together with a 4:3 display two choices of panning vector control are available: - automatic: Off-air pan vectors are used to show the desired portion of the widescreen (16:9) picture. No viewer control is allowed in this mode. If off-air pan vectors are not available, then the displayed picture, i.e. the picture area between the dashed lines in Fig. lA, is positioned in the centre of the widescreen picture.

- manual: Off-air pan vectors are ignored. The viewer has total control of the panning position, e.g. by using left and right arrow keys b a remote control.

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The above two choices of control are selected for example via a 'Panning Mode Select' menu which is part of a menu driven control system for the TV receiver.

The viewer has to make a choice before using the panning feature. If using the automatic panning mode, there is no quick way for the viewer to pan manually to an interesting part of the picture. To change to manual panning mode would take time while passing through menus and the interesting scene would have changed.

If using the manual panning mode, the viewer does not gain the benefit of knowing beforehand where the best panning position is, as a broadcaster does.

If the manual panning mode-is forgotten or the remote control arrow keys not used, the picture will remain locked in one position, say off to one side, and the viewer would miss the optimum picture.

Invention It is an object of the invention to improve the pan vector control for a viewer of TV broadcasts. This object will be reached by the features of claim 1. Advantageous additional embodiments are described in the subclaims.

The system is normally in the 'automatic' mode whereby offair pan vectors are used to control the displayed picture position. If at any time the viewer operates the pan vector controls, say the arrow keys on the remote control, then the viewer takes control of the panning vector for the duration of the remote control operation and for a predetermined time after the viewer stops the manual adjustment. When the predetermined time has expired, the receiver reverts to 'automatic' mode by homing the displayed picture in on the off-air pan vector position and then following it in the normal way.

If there is not off-air pan vector information present then a centred picture is adopted.

The viewer control of the panning vector is a continuously variable process. As the viewer changes the pan vector the displayed picture scrolls from left to right in a smooth way.

In future applications where extra vertical picture information is transmitted, a vertical pan feature of the same type could be applied. This would enable the viewer to scan the displayed picture both from left to right and up and down.

This could be controlled by a joy-stick or other means.

If extra picture definition is transmitted, the new panning feature could be applied in a three-dimensional way in order to pan and zoom the displayed picture in and out. This would give viewer control of left and right, up and down and zoom in and out, thus enabling the viewer to become more involved with the picture.

Advantageously there is no need to preselect a desired panning mode. The system is made easier by using the benefits of both automatic and manual panning control modes. The viewer does not have to remember the panning position as is necessary in the manual panning mode.

Drawings Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows different kinds of pan vector control; Fig. 2 is a block diagram of an improved pan vector con trol in a TV receiver.

Preferred embodiments Fig. 1A shows a 16:9 picture format. Within this 16:9 picture format the area of a 4:3 aspect ratio picture is marked by the dashed lines. If a TV signal, e.g. a MAC signal, with 16:9 aspect ratio is transmitted and a viewer receives this signal with a standard 4:3 display either the full transmitted picture width is not displayable or the vertical resolution of a squeezed 16:9 picture displayed within the 4:3 format (like 'letterbox' method) will decrease.

Therefore pan vectors can be transmitted which indicate the position of the main picture content in 4:3 aspect ratio within the 16:9 picture format. Thereby an automatic panning from left to right in accordance with an 'action' part of the picture can be performed.

Because a viewer could prefer to watch another part of the 16:9 picture or because the pan vectors may be not transmitted in all cases, a user control of the pan vectors should be provided.

Fig.2 shows a block diagram of a part of a TV receiver in which the pan vector control is improved. A 16:9 widescreen off-air TV signal such as HDTV, HDMAC, MUSE, D2-MAC, DMAC, CMAC, BMAC, PALplus) is received at a first input 201.

This signal has already been IF demodulated.

A pan vector filter (22) extracts the off-air pan vector from the incoming signal and a detector (21) provides a control signal to indicate its presence. This information is passed through auto centre logic (23) which allows the offair pan vector through if present or defaults to a centre position pan vector if not. The transition between off-air and centred pan vectors is smooth so as to avoid the picture jumping around, say under noisy signal conditions.

A second input 202 and a third input 203 are fed with pan control signals from a remote control. These inputs (e.g.

left and right pan controls) and the output signal from autocentre logic 23 are used to create in a pan vector generator 26 a manual pan vector which starts from the current off-air pan vector or the default pan vector and increments or decrements as the user makes an adjustment.

An OR-Logic 27 monitors the presence of a user input signal at inputs 202 and 203. During the user adjustment, and for a predefined time afterwards, a timer control signal is generated in a timer 28 which selects the manual pan vector in a mixing logic 24. When the timer control signal times out the mixing logic switches over to the off-air or default pan vector. This switching is done using a smooth scroll between the two so as to avoid a jump in the picture.

The output pan vector from the mixing logic 24 is used by a picture processing circuit 25 to select the desired 4:3 part of the incoming widescreen signal.

If extra vertical information is transmitted, the panning can be in a up or down direction (Fig. 1B). This may be applicable for text processing using computers, too.

If extra horizontal and vertical information or extended resolution is transmitted (HDTV, HDMAC, MUSE), the panning may be performed in four directions (Fig. 1C, 1D) or may include a zoom function (Fig. 1D) as indicated by the arrows. In this case a remote control may have four or six respective keys and pan vector generator 26 and OR-logic 27 may include four or more inputs.

When zooming a first picture part 11 is enlarged and includes the area of a second picture part 12. The first and/or the second picture part are located within the whole transmitted picture 13.

Claims (10)

Claims

1. Pan vector control for choosing pictures with a first picture area (12) out of the area of pictures with a second picture area (13), whereby said second picture area has a greater width (Fig. 1A, 1C, 1D) than said first picture area and said pan vector control is performed either in an automatic mode by evaluating first pan vectors, which are combined with respective signals (201) for said pictures with said second picture area, or in a manual mode by evaluating second pan vectors, which are generated (202, 203) through the action of a viewer of said pictures with said first picture format, characterised in that the standard mode is said automatic mode, whereby the occurrence of said viewer action is monitored (27) and during said action and during a predetermined time (28) after said action said pan vector control is switched from said automatic mode to said manual mode and that after said predetermined time said pan vector control is switched back to said automatic mode.

2. Pan vector control according to claim 1 characterised in that case there are no first pan vectors combined with said respective signals (201) for said pictures with said second picture area default pan vectors are assumed in said automatic mode.

3. Pan vector control according to claim 2 characterised in that said default pan vectors respect to a centred position (Fig. 1A, 1C, 1D) of said first picture area within said second picture area.

4. Pan vector control according to one or more of claims 1 to 3 characterised in that said second picture area has the same width as and a greater height than said first picture area (Fig. 1B).

5. Pan vector control according to one or more of claims 1 to 3 characterised in that said second picture area has a greater width and a greater height than said first picture area (Fig. 1C, 1D).

6. Pan vector control according to one or more of claims 1 to 5, characterised in that said second picture area has an increased resolution compared to said first picture area (Fig. 1D).

7. Pan vector control according to claims 5 and 6 characterised in that a zoom function (Fig. 1D) under the control of said viewer is provided by generating respective zoom vectors which are evaluated in a respective way to said second pan vectors.

8. Pan vector control according to one or more of claims 1 to 7, characterised in that the evaluation of said second pan or zoom vectors results in a smooth panmng or zooming.

9. Pan vector control according to one or more of claims 1 to 8, characterised in that a changing between the evaluation of said first pan vectors or of said default pan vectors results in a smooth panning.

10.Pan vector control according to one or more of claims 1 to 9, containing a pan vector filter (22) for extracting said first pan vectors, an auto centre logic (23), a detector (27) for monitoring the presence of said second pan vectors, a time (28), a mixing logic (24) for first, second, default and/or zoom vectors and a picture processing circuit (25).