JPS6387895A - Signal separating device - Google Patents

Abstract

PURPOSE:To decrease or eliminate the occurrence of unnatural images by using a movement detection circuit, an inter-frame correlation and inter-field scanning line correlation to apply Y/C separation by 1st and 2nd Y/C separation circuits, connecting them in series and controlling the 1st Y/C separation circuit by the movement detection circuit. CONSTITUTION:A 1st coefficient circuit 10 applies coefficient processing of 1-K, K(K=0-0.5) to a composite color television signal of the present frame and a 2nd coefficient circuit 201 applies that of the preceding frame respectively and they give the result to an adder 300 via conductors 101, 202. The coefficient K is controlled to be decreased with respect to the part judged to be a moving image by the moving detection circuit 3 in the 1st and 2nd coefficient circuits 10, 201 and the complete movement, in other words, large movement is set to K=0 and very small movement is set to 0<K<0.5. Thus, each of Y and C signals is subjected to optimum control to changes in standstill and movement and unnatural image quality deterioration is prevented or decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal separation device for separating a luminance signal (Y signal) and a carrier color signal (C signal) of a composite color television signal.

Conventional technology When separating these two types of signals from a composite color television signal in which a luminance signal and a chrominance signal such as an NTSC signal are frequency multiplexed, inter-frame correlation and inter-scanning line correlation of the image are used. Various apparatuses have been proposed for separating inter-correlations in moving image parts using inter-scanning correlations. FIG. 3 shows an example of such a signal separation device as described in Japanese Patent Publication No. 15635/1983. In this device, a composite color television signal supplied to a signal input terminal 1 is input to a frame memory 2, a motion detection circuit 3. The interframe luminance signal and the carrier color signal (Y/C> are supplied to the separation circuit 4 and the intrafield Y/C separation circuit 6, respectively, and the motion detection circuit 4 receives one frame from the frame memory 2 via the conductor 2o. The moving part of the image is detected using interframe correlation with the previous signal, and the interframe Y
The /C separation circuit 4 sends a Y signal and a C signal to conductive wires 40 and 41, respectively, by performing addition and subtraction processing between two signals that are relatively different by one frame period. The intra-field Y/C separation circuit 6 uses the correlation between the scanning lines of the signal supplied from the signal input terminal 1 to perform addition and subtraction processing on a plurality of scanning lines, and sends the Y signal and C signal to conductors 50 and 51, respectively. do. Interframe Y/C separation circuit 4. Inter-field Y/C separation circuit 5
The first signal selection or mixing circuit θ, to which the Y signal is supplied via conductors 40 and 60, respectively, is connected to the control signal supplied from the motion detection circuit 3 via the conductor 30. In the moving portion of the image, the first signal selection or mixing circuit θ is connected to the conductor 6o. In the stationary portion, the Y signal from the conductor 4o is selected, and the Y signal from the conductor 4o is selected and sent to the signal output terminal 7. The second signal selection or mixing circuit 8 also selects the C signal from the conductor 61 in the moving part of the image, and the C signal from the conductor 41 in the static part by the control signal from the motion detection circuit 3 via the conductor 30. A C signal is sent to the signal output terminal 9.

Problems to be Solved by the Invention As mentioned above, inter-frame Y/C with a frame memory
A separation circuit and an in-field Y/C separation circuit are arranged in the return circuit, and an image motion detection circuit is arranged to detect the presence or absence of image movement or the degree of movement, and outputs from two types of Y/C separation circuits. With known signal separation devices that switch or mix signals, the image quality deteriorates significantly when a part of the image moves or when the degree of image movement is minute, and in particular, unnatural distortion occurs in the image. I have a problem. This is, for example, the first signal selection when considering the interference of the C signal to the Y signal, that is, the dot interference, and the mixing circuit 6 selects the first signal when mixing two input Y signals each month according to the control signal from the conductor 30. Output terminal 7
Then, the interframe Y/C separation circuit 4 sends out the Y signal for the static portion, which is supplied from the interframe Y/C separation circuit 4 in which dot interference remains in the horizontal contour portion of the image where the correlation between scanning lines is strong. Since the Yi code for the still portion is subjected to inter-frame addition processing, dot interference remains on the contours of the latent codes of two different frames, resulting in a significant deterioration in image quality.

Means for Solving the Problems The signal separation device of the present invention receives a composite color television signal as input, and uses a motion detection circuit that utilizes interframe correlation, and interframe correlation and intrafield inter-scanline correlation, respectively. /C first and second Y/C separation
The C separation circuits are arranged in series, and the first Y/C
The motion detection circuit is configured to control the separation circuit.

Operation The motion detection circuit detects the moving part of the image and its degree based on the difference signal between frames, and the first Y/C5+ separation circuit detects the total motion of two types of signals between different frames in addition and subtraction processing. With the gain constant, the calculation amplitude ratio is changed to increase the signal of the current frame depending on the degree of movement, and the signal is equal in static parts, and in moving parts, the signal is divided by $1 Y/C in parts judged to be complete movement. The circuit is controlled by the motion detection circuit to stop the interframe Y/C separation operation and output only the signal of the current frame. The second signal separation circuit uses the output signal of the first signal separation circuit as input and uses the correlation between multiple scanning lines to perform Y/C processing.
The separation is processed uniformly for static and moving parts of the image.

Embodiments Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a signal separating device according to an embodiment of the present invention, in which a composite color television signal supplied to a signal input terminal 1 is transmitted to a frame memory 200. Motion detection circuit 3. The coefficients are respectively supplied to the first coefficient circuit 10. The frame memory 200 includes a second coefficient circuit 2o1. A composite color television signal of the previous frame is supplied to the other input of the motion detection circuit 3, and the first coefficient circuit 1o receives the composite color television signal of the current frame, and the second coefficient circuit 201 receives the composite color television signal of the previous frame, respectively. 1- is subjected to coefficient processing of K (K=O to 0.5) and is supplied to the adder 300 via conductive wires 101 and 202'i. These first. The second coefficient circuit 10.201 has its coefficient changed by a control signal supplied from the motion detection circuit 3 via the conductor 31, and in the still image portion, the coefficient is set to 0.5 and sent to the conductor 101.202. By setting the amplitudes of the frame and the previous frame to be equal and adding them in adder 300, all C signal components are removed and only the Y signal component is sent to conductor 301. On the other hand, the first and second coefficient circuits 10 and 201 are controlled to reduce the coefficient K for a portion determined to be a moving image by the motion detection circuit 3, so that there is no complete motion, in other words, the degree of motion is large. For some parts, 2 = o, and for parts where the degree of movement is minute, O < K
(set to o, s. Therefore, the adder 300 adds only the Y signal in the static part of the image, and adds the signals of the current frame and the previous frame at a predetermined amplitude ratio depending on the degree of movement in the moving part. , only the composite color television signal of the current frame is sent on conductor 301 during full motion portions.

In the present invention, the two-dimensional low-pass filter circuit 400 to which the output signal of the adder 300 is supplied is the first. 2nd coefficient circuit = o
That is, in a completely moving part, the adder 300 performs vertical and horizontal correlation processing on the signal components of the current frame to remove high-frequency signal components in the diagonal direction of the image. The two-dimensional low-pass filter circuit 400 removes or attenuates oblique high-frequency components of the C signal and the Y signal in the vicinity thereof, but the number of scanning lines and the number of pixels in the horizontal direction are not limited.

Also number 1. In a still part of the image where the second coefficient circuit K=0.5, the high frequency signal component in the diagonal direction is removed or attenuated from only the Y signal component outputted by the adder 300. On the other hand, the first. The second coefficient circuit is 0(K(0,6
For parts where the degree of movement is minute,
For example, in a portion determined to be between stationary and moving, the value is set to 0.25, and therefore the adder 30o is set to 0.25.
Amplitude ratio 0.75:0 supplied via 1,202
．． For the summed signals of the 25 current and previous frames, C signal components are removed from portions that have correlation in the vertical and horizontal directions. Therefore, Y signal output terminal 50
0 contains a Y signal with diagonal high-frequency components attenuated in the stationary part, and a Y signal containing a slight C signal component in the diagonal direction that has no correlation with either the vertical or horizontal direction in the moving part. is output. Subtractor 11 is adder 3
00 through conductive wires 101 and 202. The second coefficient circuits 1o and 2Off perform subtraction of signals that are relatively different by one frame, and in the stationary portion, the two input signal amplitudes are set to be equal, all Y signals are removed, and only the C signal is output.

In addition, in the moving part, in a part where the degree of movement is minute, the signal amplitude of the current frame supplied from the conductor 1o1 is increased, as in the adder 300, while the signal amplitude of the previous frame supplied from the conductor 202 is decreased. A signal in which a C signal component, which is the result of subtraction between these components, and a small Y signal component are mixed is output, and in a part where there is complete motion, a signal of only the current frame, that is, a composite color television signal is output. The two-dimensional high-pass filter circuit 600 to which the output signal of the subtractor 11 is supplied does not substantially limit the band of the C signal in the stationary part where only the C signal is supplied, and in the moving part the two-dimensional high-pass filter circuit 600 Vertical of the Y signal component mixed into the input signal provided at 110.

Components having horizontal correlation are removed. Therefore, the C signal output terminal 700 has a Y signal in the stationary part.
Only a C signal that does not contain any signal is output, and a C signal that includes a slight Y signal component in an oblique direction that has no correlation with either the vertical or horizontal directions is output in a portion that involves movement.

FIG. 2 shows another embodiment of the present invention, in which the subtracter 11 is supplied with the signals of the current frame and the previous frame from third and fourth coefficient circuits 12, 202, respectively. The fourth coefficient circuit 12.degree. 202 is controlled by a signal supplied from the motion detection circuit 3 via the conductor 32.

This embodiment has the advantage that when performing interframe Y/C separation, the coefficient control for the moving parts of the Y signal and C signal can be changed independently. Therefore, each of the Y signal and C signal can be optimally controlled for changes in stillness and motion, and unnatural deterioration in image quality can be prevented or reduced.

Effects of the Invention The signal separation device according to the present invention has an inter-frame Y/C separation circuit and an intra-field two-dimensional Y/C separation circuit configured in series. This has great industrial value, as it can improve the separation effect and reduce or eliminate significant changes in image quality or the occurrence of unnatural images due to motion adaptive control.

Further, although the frame memory for Y/C separation between frames is assumed to be for one frame for convenience of explanation, various modifications and applications such as arranging a plurality of frame memories are possible.

[Brief explanation of the drawing]

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 invention, and FIG. 3 is a block diagram of a signal separation device in a conventional example. It is. 1... Signal input terminal, 200... Frame memory, 3... Motion detection circuit, 10.20
1... Coefficient circuit, 300... Adder,
11... Subtractor, 400... Two-dimensional low-pass filter circuit, 600... Two-dimensional high-pass filter circuit,
500, 700...Signal output terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure σ Figure 2 Figure 2 Figure 3

Claims (2)

[Claims] (1) A motion detection circuit that receives a composite color television signal as input and detects static or moving parts of an image using inter-frame correlation, and a luminance signal and carrier color that uses inter-frame correlation and intra-field inter-scanning line correlation. the first and second signal separation circuits are connected in series, and the motion detection circuit detects the luminance signal of the first signal separation circuit for a moving portion of the image. - A signal separation device characterized by controlling the carrying color signal separation operation to be suppressed or stopped. (2) A first signal separation circuit sends out a sum signal and a difference signal between frames, and a second signal separation circuit receives the sum signal and difference signal, respectively, and performs calculations on at least a plurality of scanning lines. The signal separation device according to claim 1, characterized in that the signal separation device is a two-dimensional low-pass filter circuit and a two-dimensional high-pass filter circuit.