JP2600196B2 - Signal separation device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal signal separation apparatus in which a luminance Y signal and a color C signal are frequency-multiplexed as in the NTSC system.

2. Description of the Related Art Conventionally, as a signal separation device of this type, a frame memory is provided, and a motion image detecting circuit that determines a motion image or a still image by using inter-frame correlation of an image, a Y / C separation circuit between frames, an intra-field Various types of so-called motion-adaptive Y / C separation devices have been proposed in which each output signal of the Y / C separation circuit is adaptively switched by the output of the motion detection circuit or mixed at a predetermined ratio.

FIG. 3 shows a conventional example of such a Y / C separation apparatus, which will be described below with reference to the drawings. In FIG. 3, the signal supplied to the signal input terminal 1 is divided into first and second signals.
After delaying in the frame memories 2 and 3 and obtaining signals different in time by one frame or two frames relative to the conductors 4, 5 and 6, the inter-frame Y / C separation circuit 7 and the intra-field Y / C separation circuit 8, a Y / C separation process for a still image portion and a Y / C separation process for a motion image portion is performed.
Detects a still image portion and a moving image portion. Conductors 10, 11
The signal selection circuit 12 to which the output signals of the inter-frame Y / C separation circuit 7 and the intra-field Y / C separation circuit 8 are supplied via
The output signal of the motion detection circuit 9 supplied via the conductor 13 is used as a control signal to select the conductor 10 side for the still image portion and the conductor 11 side for the motion image portion or to mix them at a predetermined ratio. A Y signal is sent to one signal output terminal 14. The subtractor 15 subtracts the Y signal from the conductor 16 and the input television signal from the conductor 4 and sends a C signal to the second signal output terminal 17.

Problems to be Solved by the Invention The inter-frame Y /
A C separation circuit and an intra-field Y / C separation circuit are arranged in parallel, and a motion detection circuit using inter-frame correlation is arranged to detect the presence or absence of the motion of the image or the degree of the motion. Known signal separation devices that switch or mix the output of the / C separation circuit on a pixel-by-pixel basis tend to produce images with intermediate movements or unnatural images due to imperfections in the detected motion signals. have. For example, for an image with intermediate movement,
The C separation circuit sends out a composite signal of the image signals of two different frames, but the vertical, horizontal, or diagonal contour portions where the inter-frame transmission is significantly reduced by the motion of the image are substantially Y / C. Separation cannot be performed, and the image quality is degraded due to the remarkable increase in interference between the Y signal and the C signal. The imperfectness of a motion signal is generally obtained, for example, in a motion detection circuit using inter-frame transmission, by obtaining an inter-frame difference signal and processing the difference signal to generate a motion signal. Noise components and the like mixed into the image are easily detected as motion signals. This erroneous motion signal may significantly degrade the Y / C separation performance in order to process a part of the still image part as a motion image, or to process a part of an actually moving image as a still image. It has disadvantages such as deterioration of image quality.

Means for Solving the Problems In order to solve the above problems, a signal separating apparatus according to the present invention comprises a frame memory for delaying a frequency-multiplexed input color image signal, and a first memory to which the input color image signal is supplied. An intra-field Y / C separation circuit, a second intra-field Y / C separation circuit to which a color image signal delayed by one frame is supplied by the frame memory;
An inter-frame Y / C separation circuit that performs arithmetic processing on each output signal of the intra-field Y / C separation circuit, a motion detection circuit using inter-frame correlation, and the first signal as a control signal using the output signal of the motion detection circuit. A signal selection circuit is provided for mixing or switching the respective output signals of the intra-field Y / C separation circuit and the inter-frame Y / C separation circuit at a predetermined ratio.

Operation The Y / C separation circuit in the first field receives the color image signal of the first frame, which is the input signal of the frame memory, and uses the neighborhood correlation in the vertical direction, the horizontal direction, and the like in a single field to obtain a Y signal. / C separation processing, while the Y / C separation circuit in the second field performs the Y / C separation for the color image signal that differs from the input of the Y / C separation circuit in the first field by one frame.
Perform C separation. The inter-frame Y / C separation circuit to which the Y signal or the C signal output from the Y / C separation circuit in the first and second fields is supplied converts the signal for the still image portion by adding or subtracting two signals. Output. The signal selection circuit to which the output signals of the inter-frame Y / C separation circuit and the first-field Y / C separation circuit are supplied uses the output signal of the motion detection circuit as a control signal, and the pixel determined to be a still image portion is used. Is the signal from the inter-frame Y / C separation circuit, and the pixel determined to be the moving image portion is the Y / C in the first field.
A signal from the separation circuit is selected, and these two types of signals are mixed at a predetermined ratio for an image having an intermediate movement. The motion detecting circuit detects a still portion and a moving portion of the image based on a difference signal of a signal which is supplied by a frame memory and is relatively different by one or two frames, and supplies a control signal to a signal selection circuit.

Embodiments Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a signal separating apparatus according to an embodiment of the present invention. In FIG. 1, a color image signal supplied to a signal input terminal 20 is converted into first and second frame memories 21 and 22. , And outputs the color image signals of the current frame, one frame before and two frames before to the conductors 23, 24 and 25, respectively. The Y / C separation circuit 26 in the first field, to which the color image signal of the current frame is supplied via the conductive line 23, performs Y / C separation using the near correlation between the images in the vertical and horizontal directions within a single field. Do. For example, when extracting a Y signal, the first-field Y / C separation circuit 26 is constituted by a two-dimensional low-frequency three-wave circuit, and the C
The Y signal from which the signal has been removed is transmitted.

The color image signal of one frame before is supplied to the Y / C separation circuit 28 in the second field via the lead 24, and the Y / C separation circuit 28 using the same neighborhood transfer as the Y / C separation circuit 26 in the first field is used. / C separation processing is performed and a Y signal is output to the conductor 29. Therefore, the Y signals transmitted to the conductors 27 and 29 respectively are Y /
The addition process is performed in the C separation circuit 30, and the signal is transmitted to the lead 31 as a still image portion signal.

The motion detection circuit 32 performs a subtraction process between the color image signals of the current frame, the previous frame, and the previous two frames supplied via the conductors 23, 24, and 25, and performs the subtraction for one frame obtained by this process. A signal representing the motion of the image is generated based on the difference signal between two frames. In the NTSC signal, since the phase of the C signal frequency-multiplexed with the Y signal makes one cycle in two frames, motion detection using the difference signal between two frames can detect image motion over a wide band. However, the motion detection may be incomplete for an image accompanied by a special motion due to being between two frames, for example, a motion that actually moves but overlaps between the two frames. Therefore, C of the difference signal between one frame
It is necessary to use a relatively narrow band portion which is not affected by a signal in order to perform good motion detection. These one
Performing motion detection by combining both difference signals between frames and between two frames, or using one of them can be appropriately selected. The motion detection circuit 32 is a signal selection circuit via the conductor 33 by the above-described processing.
The control signal is supplied to a signal selection circuit 34 which selects the still image portion on the conductor 31 side and the moving image portion on the conductor 27 side, and selects the two types of signals for the image portion with intermediate movement. And sends a Y signal to the signal output terminal 35.

FIG. 2 is a block diagram showing a configuration of a signal separation device according to another embodiment of the present invention, which constitutes first and second intra-field Y / C separation circuits 26 and 28 and an inter-frame Y / C separation circuit. An apparatus for extracting a Y signal comprising an adder 30 'and a first signal selection circuit 34' is equivalent to the embodiment of FIG. 1 described above, and sends out a Y signal to a first signal output terminal 35 '.

A subtractor 36 for subtracting the input and output signals of the Y / C separation circuit 26 in the first field sends the C signal of the current frame processed in the field on a lead 37, while the Y / C separation circuit in the second field. A subtractor 38 for subtracting the input and output signals of 28 sends out the C signal of the previous frame to a conductor 39. The subtractor 40 to which the current frame processed in the single field and the C signal of the previous frame are supplied constitutes an inter-frame Y / C separation circuit for the C signal, and the second signal selection circuit 41 The C signal for the still image portion is supplied to the circuit 42. Conductor 4
The second signal selection circuit 42 to which the C signals for the still image portion and the motion image portion are supplied at 1 and 37, respectively, is based on the control signal supplied through the lead 33, that is, in response to the motion of the image. The C signal subjected to the motion adaptive Y / C separation processing is transmitted to the second signal output terminal 43.

According to the present invention, Y / C separation between frames is performed after performing Y / C separation within a field on a color image signal which is relatively different by one frame, and the Y / C separation between frames is performed. Y and C signals are obtained by adaptively switching the output and the in-field Y / C separation processing output for the current frame color image signal with the detected image motion signal, or by mixing at a predetermined ratio. Is what you do. Therefore, for an image having an intermediate motion, particularly, the crosstalk between the Y signal and the C signal in the outline portion is greatly reduced and the motion signal generated when the S / N of the input color image signal is reduced. This is of great industrial value, such as preventing the deterioration of the Y / C separation result based on imperfection.

[Brief description of the drawings]

FIG. 1 is a block diagram of a signal separation device in one embodiment of the present invention, FIG. 2 is a block diagram of a signal separation device in another embodiment of the present invention, and FIG. 3 is a block diagram of a signal separation device in a conventional example. It is. 20 ... Signal input terminal, 21,22 ... Frame memory, 26,28
…… Y / C separation circuit in the field, 30, 30 ′ …… Between frames
Y / C separation circuit, 32: Motion detection circuit, 34, 34 ', 42 ... Signal selection circuit, 35, 35', 42 ... Signal output terminal.

Claims (2)

(57) [Claims] A frame memory for delaying a frequency-multiplexed input color image signal; a first-field Y / C separation circuit to which the input color image signal is supplied; and a color delayed by one frame by the frame memory. A Y / C separation circuit in a second field to which an image signal is supplied, an inter-frame Y / C separation circuit for arithmetically processing output signals of the first and second in-field Y / C separation circuits, A motion detection circuit using correlation, and the output signals of the first field Y / C separation circuit and the inter-frame Y / C separation circuit are mixed at a predetermined ratio using the output signal of the motion detection circuit as a control signal. And a signal selection circuit for switching. 2. The method according to claim 1, wherein each of the first and second intra-field Y / C separation circuits, the inter-frame Y / C separation circuit, and the signal selection circuit are Y
2. The signal separation device according to claim 1, further comprising a circuit for a signal and a circuit for a C signal.