JP2538966B2 - Character superimpose method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-definition transmission system, and more particularly to a character superimposing system after MUSE signal coding.

(Summary of the Invention) The present invention relates to a character superimposing method after MUSE signal coding. When superimposing a character or the like on a coded MUSE signal for high-definition, at least as a character signal generator, MU to be imposed
A device that supplies a character signal sampled at the same phase as the sampling phase of the SE signal is used.

As a result, the MUSE signal can be decoded once and the character superimposition can be performed without returning to the normal television signal, and the image quality is not compromised.

(Prior Art) Conventionally, since it was not considered to further process the high-definition MUSE signal after the coding, there is no technology similar to the present invention.

Regarding the MUSE method technology, patent application to become the applicant,
Japanese Patent Application No. 60-106132 (Japanese Patent Application Laid-Open No. 61-264889) “Multiple Sub-Sample Transmission System”, Japanese Patent Application No. 61-13675 (Japanese Patent Application Laid-Open No. 62-1)
72895) "Sub-sample encoder", Japanese Patent Application No. 61-136
See No. 40 “Decoder configuration method”.

(Problems to be Solved by the Invention) In the MUSE method, it is not possible to use the motion vector correction-sampling method and to mix other signals directly because the nonlinear emphasis is used.

On the other hand, apart from full-fledged mixing, if something happens in the middle of the network, such as a simple character superimpose, it is necessary to consider a countermeasure for it.

To answer the above need, the present invention provides a method for superimposing a character symbol or the like on a coded MUSE signal using a simple device.

(Means for Solving Problems) That is, according to the character superimposing method of the present invention, in performing character superimposing on a coded high-definition MUSE signal, at least sampling of the MUSE signal superimposed is performed. A character signal generator for generating a character signal sampled at the same phase as the phase is used.

(Example) The present invention will be described in detail below with reference to the accompanying drawings. The embodiment described here is an example including the claims up to claim 4 described at the beginning, and some functions are lost with respect to other claims.

FIG. 1 shows a schematic block diagram of an embodiment of an apparatus necessary for carrying out the method of the present invention. The operation of the method of the present invention will be described below with reference to the configuration example of the first illustrated device.

The MUSE input signal to be superimposed on the character is transmitted to the MUS by the block 1 through, for example, a video distribution amplifier (VDA).
The sync signal, control signal, and clock signal are separated from the E signal. This part is exactly the same as part of the MUSE signal decoder already developed and described in various documents.

The sync signal separated by the block 1 drives the opaque device 3 which is a source of characters and the like, and the sync signal is temporally adjusted so that the character signal which has been processed at this time has the same timing as the MUSE signal. It The character source is not necessarily limited to an opaque device, which may be a television camera or a character generator type.

Next, the character signal is a low-pass filter (LPF) of about 15MHz.
A / D conversion is performed by A / D conversion 5 with a clock of 32.4 MHz via 4. The purpose of passing a relatively narrow band LPF prior to A / D conversion is to eliminate the need to consider the phase of the inter-field offset subsampling, and even this level of character quality is sufficient. Is.

The character signal A / D converted by the A / D converter 5 is a transversal filter of about 5 lines (H) × 7 taps,
That is, after passing through a two-dimensional LPF having the characteristics of a motion region filter used for signal processing of the MUSE signal, MUSE
Subsampling (16.2 MHz) is performed by the subsampling circuit 7 in accordance with the inter-frame offset subsampling phase for the luminance signal.

Finally, the sub-sampled signal is emphasized by the emphasis circuit 8 of the MUSE standard to obtain a superimpose signal, and LP for transmission matching is further obtained.
Although filtered by F9, this emphasis and transmission matching need not be as perfect as the MUSE encoder.

After the above processing, the mixing distribution ratio of the superimposing signal and the superimposing signal is changed according to the level of the superimposing character signal, and the sum signal level of both is always the highest level of the MUSE signal. Do not exceed or keep the level of the character signal for superimposing always lower than the maximum level of the MUSE signal.
This part is implemented by the level detector of block 10 to the D / A converter of block 15 and LPF in the first illustrated configuration. In the configuration shown in the first diagram, the last is analog signal processing,
The method is not limited to this method, and the signal level control on the superimposing side can be adopted as a table look method using a ROM, so that the apparatus becomes simpler.

In this embodiment, since the superimpose signal is monochrome (black and white), the signal on the superimpose side is zero for all of the sync signal portion, the control signal portion and the color signal portion (actually, the level detection control may be performed in this way. ), The input MUSE signal is output as it is during that period.

If you need a character superimpose with a color signal, create a color signal system similar to the luminance signal system,
After that, the time axis compression multiplexing (TCI) process can be performed to obtain a colored superimpose signal, or the signal can be first TCI processed and subsampled according to the sampling phase of each of the luminance signal and the color signal. .

(Effects of the Invention) As described above in detail, according to the method of the present invention, in superimposing a character or the like on the MUSE signal for high-definition, at least as a character signal generator, the MUSE signal is superimposed. Since the character signal sub-sampled in the same phase as the signal sampling phase is supplied, the MUSE signal to be superimposed is decoded once, and character superimposing is possible without returning to the normal television signal. Therefore, the image quality of the image due to the superimposed MUSE signal is not compromised.

[Brief description of drawings]

FIG. 1 shows a schematic block diagram of an embodiment of an apparatus required to carry out the method of the present invention. 1 …… Synchronization, control, clock signal separation and PLL 2 …… Video distribution amplifier, 3 …… Opaque device 4,9 …… LPF, 5 …… A / D converter 6 …… Two-dimensional LPF 7 …… Subsampling Circuit 8 …… Emphasis circuit, 10 …… Level detector 11,16 …… Multiplier, 12 …… Adder 13 …… Inverter 14,15 …… D / A converter and LPF

Claims (5)

(57) [Claims] 1. A character signal generator for generating a character signal sampled at the same phase as the sampling phase of the superimposed MUSE signal when performing character superimposing on a coded high-definition MUSE signal. Character superimpose method characterized by using. 2. The method according to claim 1, wherein the sampling phase included in the control signal of the superposed MUSE signal is used in determining the sampling phase to be superimposed. Character superimpose method characterized by. 3. The method according to claim 1 or 2, wherein the superimposing character signal is processed in advance by a two-dimensional or one-dimensional low-pass filter,
Character superimpose method that removes the mixture of folding components. 4. The system according to claim 3, wherein the mixing distribution ratio of the superimposing signal and the superimposing signal is changed according to the level of the superimposing character signal. The character superimpose method is characterized in that the sum signal level of does not always exceed the maximum level of the MUSE signal. 5. The character superimposing method according to claim 3 or 4, wherein the level of the superposed character signal is always kept lower than the maximum level of the MUSE signal. method.