JP2000209611A - Color signal vertical interpolation filter and color signal vertical interpolation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a color signal vertical interpolation filter that eliminates the need of plural delay circuits and to realize its color signal vertical interpolation method. SOLUTION: The color signal vertical interpolation filter 10 consists of a switch 12, a memory 13, amplifiers 14, 15 and a mixer 16. Each horizontal period signal of 4:2:0 color signals is given twice to the color signal vertical interpolation filter 10. The received horizontal period signal is branched into a 1st signal 17 and a 2nd signal 18, and the 2nd signal 18 is given to a memory 13 at an interval of one horizontal period. Then the memory 13 reads the received 2nd signal 18 with a delay twice each, the read 2nd (1st) signal 18 (17) are amplified by the amplifier 14(15), a mixer mixes the amplified signals to produce 4:2:2 color signals 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal vertical interpolation filter and a color signal vertical interpolation method for performing vertical interpolation of a color signal, and more particularly to converting a 4: 2: 0 color signal into a 4: 2: 2 color signal. The present invention relates to a color signal vertical interpolation filter and a color signal vertical interpolation method.

[0002]

2. Description of the Related Art In recent years, the development of digital video for recording image information as digital signals on a recording medium has been actively performed.

In such a digital video, image information is composed of one luminance (Y) signal and two color information (Cr, Cb).
The signal is processed as a digital signal sampled.
Luminance is information indicating the brightness of an image, and is defined by ITU (Inter
national TelecommunicationUnion) ITU-R Recommendation 6
In 01, the luminance of the pixel is represented by 8 bits. The color information is information indicating the color of an image, and is also defined in ITU-R Recommendation 6
In 01, the color of a pixel is represented using two 8 bits.

As described above, such digital image processing requires information allocation of a total of 24 bits per pixel. However, in MPEG2 or the like, the data rate of image information is reduced in order to lower the data rate of image information recording and reproduction. Compression is performed. Such compression of image information is generally performed by deleting color information using the fact that humans are not sensitive to color. One luminance (Y) information and two color information (Cr, Cb) are used. Is represented as 4: 2: 0 using the ratio of the information amount.

[0005] In the case of 4: 2: 0, for each horizontal section (horizontal line), only a line (sample) in which only luminance (Y) and color information (Cr) having an information amount of half the luminance (Y) are sampled. 4: 2: 0) and a line (4: 0: 2) in which only the color information (Cb) consisting of the luminance (Y) and half the information amount of the luminance (Y) are sampled alternately. . Therefore, the number of bits of color information can be reduced to ４, and the total number of bits including luminance can be reduced to １ ／.

In order to output the compressed 4: 2: 0 digital signal to a monitor as image data, it is necessary to convert the signal into a 4: 2: 2 digital signal. As shown in FIG. The 4: 2: 0 color signal 100 of the 4: 2: 0 digital signal has a configuration in which h horizontal section signals 102 in which h pixel signals 101 are arranged in the horizontal direction are arranged in the vertical direction. Is output as 4: 2: 2 digital signal image data, it is necessary to convert the signal into (v × 2) horizontal section signals by interpolating the vertical direction with a color signal vertical interpolation filter.

A conventional color signal vertical interpolation filter has the following four steps:
The 2: 0 color signal is read out twice per one horizontal section signal 102, and is converted into (v × 2) horizontal section signals by using two delay lines.

FIG. 5 shows the operation of the conventional color signal vertical interpolation filter. The conventional color signal vertical interpolation filter reads out four times from C0 to Cv-1 twice.
By writing a part of the 2: 0 color signal to the delay line (1) or the delay line (2), reading it out, and synthesizing the color signal read from the delay line and the color signal not passing through the delay line, C'0
, A 4: 2: 2 color signal of C ′ (2v−1) is created.

[0009]

However, in general, the circuit scale of a delay line is larger than that of other logic units.
The conventional color signal vertical interpolation filter using a plurality of delay lines has a problem that the circuit scale cannot be reduced.

A conventional color signal vertical interpolation filter is:
Since the read 4: 2: 0 color signal is always written to or read from the delay line, there is a problem that it is difficult to reduce power consumption.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to provide a color signal vertical interpolation filter and a color signal vertical interpolation method which can be constituted by only one delay circuit.

[0012]

According to the present invention, in order to solve the above-mentioned problems, in a color signal vertical interpolation filter for converting the input of a 4: 2: 0 color signal to the output of a 4: 2: 2 color signal, First signal strength conversion means for multiplying the color signal strength of the signal by a first constant having two different values, switch means for outputting an input signal every other horizontal interval, and output from the switch means One delay circuit for delaying the input signal by one horizontal section or two horizontal sections; and a second signal for multiplying the color signal intensity of the input signal output from the delay circuit by a second constant having two values. Signal converting means, and signal synthesizing means for synthesizing an input signal whose strength has been converted by the first signal strength converting means and an input signal whose strength has been converted by the second signal strength converting means. Characteristic color No. vertical interpolation filter is provided.

Here, the first signal strength conversion means multiplies the color signal strength of the input signal by two constants, the switch means outputs the input signal every other horizontal interval, and the delay circuit outputs the signal from the switch means. The output input signal is delayed by one horizontal section or two horizontal sections, the second signal strength converting means multiplies the color signal strength of the input signal delayed by the delay circuit by two constants, and the signal synthesizing means. An input signal whose intensity has been converted by the first signal intensity converter and an input signal whose intensity has been converted by the second signal intensity converter are synthesized.

Further, the input of the 4: 2: 0 color signal is changed to 4: 2:
In a color signal vertical interpolation method for converting to an output of a two-color signal, the color signal intensity of the input signal is multiplied by a first constant having two values, and the input signal is output every other horizontal interval;
Delaying the input signal output every other horizontal interval by one horizontal interval or two horizontal intervals, multiplying the color signal intensity of the delayed input signal by a second constant having two different values, Combining an input signal multiplied by a constant with a first constant and an input signal multiplied by a constant with the second constant;
And a color signal vertical interpolation method is provided.

By adopting such a color signal vertical interpolation method, it is possible to perform vertical interpolation from a 4: 2: 0 color signal to a 4: 2: 2 color signal, which does not require a plurality of delay circuits.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a color signal vertical interpolation filter 10 according to the present embodiment.

Color signal vertical interpolation filter 1 in the present embodiment
0 indicates that the input 4: 2: 0 color signal 20 is the first signal 17.
, A branch point 11 for branching into a second signal 18, an amplifier 15 as first signal strength conversion means for multiplying the color signal strength of the first signal 17 by a constant, and outputting the input second signal 18 every other horizontal section A switch 12, a memory 13 as a delay circuit for delaying the second signal 18 output from the switch 12, and a second signal for multiplying the color signal intensity of the second signal 18 output from the memory 13 by a constant. An amplifier 14 serving as an intensity converting means, and a mixer 16 serving as a signal synthesizing means for synthesizing the first signal 17 and the second signal 18 whose intensity has been converted.
It is constituted by. Here, each of the amplifiers 14 and 15 can switch the amplification output in two stages.

The branch point 11 is electrically connected to the switch 12 and the amplifier 15, and the amplifier 15 is electrically connected to the mixer 16. The switch 12 is electrically connected to a memory 13, and the memory 13 is electrically connected to a mixer 16 via an amplifier 14.

FIG. 2 shows the relationship between the 4: 2: 0 color signal 20 input to the color signal vertical interpolation filter 10 and the 4: 2: 2 color signal 30 which has been subjected to the color signal vertical interpolation by the color signal vertical interpolation filter 10. Shows the relationship.

The 4: 2: 0 color signal 20 is output from C0 to Cv-
It has up to 1 v horizontal interval signals, and this 4:
By filtering the 2: 0 color signal 20 by the color signal vertical interpolation filter 10, C′0 to C ′ (2
The signal is converted into a 4: 2: 2 color signal 30 having (2 × v) horizontal section signals up to v-1).

Here, the horizontal section signal Cx (x is an integer less than or equal to v-1) of the 4: 2: 0 color signal 20 and the horizontal section signal C′x (x is 2v−2) of the 4: 2: 2 color signal 30 are used. The relationship of 1 or less (1 integer) is given by the following equation. Where α and γ
Represents a constant.

[0022]

## EQU1 ## When x is an even number: C'x = αC (x ÷ 2) + βC (x ÷ 2 + 1) (0 ≦ α ≦ 1, β = 1-α) When x is an odd number: C ′ x = γC ((x−1) ÷ 2) + δC ((x−1) ÷ 2 + 1) (0 ≦ γ ≦ 1, δ = 1−γ) (1) In this equation 1, x = Substituting the values of 0, 1, 2, and 3, x = 0,
The relationship between the horizontal section signal of the 4: 2: 2 color signal 30 and the horizontal section signal of the 4: 2: 0 color signal 20 in 1, 2, and 3 is as follows.

[0023]

C′0 = αC0 + βC1 C′1 = γC0 + δC1 C′2 = αC1 + βC2 C′3 = γC1 + δC2 (2) As can be seen from Equation 2, one 4: 2 : 0 color signal 20 is converted into four 4: 2: 2 color signals 30 after conversion.
Affects the horizontal section signal.

FIG. 3 is a timing chart showing the operation of the color signal vertical interpolation filter 10. In FIG. 3, the horizontal axis is the time axis, and the temporal boundaries of the horizontal sections of the 4: 2: 2 color signal 30 are indicated by 0, 1H, 2H, 3H. The vertical axis represents the 4: 2: 0 color signal 20 input to the color signal vertical interpolation filter 10 in each horizontal section, the second signal 18 input to the memory 13, the second signal 18 output from the memory 13, And synthesized by mixer 16:
A 2: 2 signal 30 is shown.

Next, using FIG. 1, FIG. 2, FIG.
The specific operation of the color signal vertical interpolation filter 10 will be described. First, in horizontal sections 0 to 1H shown in FIG.
The leading horizontal section signal C0 of the 2: 0 color signal 20 is input to the color signal vertical interpolation filter 10. The input horizontal section signal C0 is converted to the first signal 1 by the branch point 11 shown in FIG.
7 and a second signal 18, and the first signal 17 is
Reaches 5. At this time, the switch 12 is not closed and the second signal 18 of the horizontal section signal C0 is not input to the memory 13.

In the next horizontal section 1H to 2H, the same horizontal section signal C0 is again input to the color signal vertical interpolation filter 10. Similarly, the horizontal section signal C0 is branched into a first signal 17 and a second signal 18, and the first signal 17 reaches the amplifier 15. This time, the switch 12 is in the closed state, and the second signal 18 of the horizontal section signal C0 is input to the memory 13 via the switch 12.

In the next horizontal section 2H to 3H, the next horizontal section signal C1 is input to the color signal vertical interpolation filter 10. The input first signal 17 of the horizontal section signal C 1 reaches the amplifier 15. At this time, the switch 12 is not closed, and the second signal 18 of the horizontal section signal C1 is not input to the memory 13. However, the second signal 18 of the horizontal section signal C0 input to the memory 13 during the immediately preceding horizontal section 1H to 2H is output from the memory 13 with a delay of one horizontal section from the memory 13.

In the horizontal sections 2H to 3H, the amplifier 1
The signal output of the first signal 17 of the horizontal section signal C1 that has reached 5 is converted by the amplifier 15 into an intensity β times. The second signal 18 of the horizontal section signal C0 output from the memory 13 with a delay of one horizontal section is subjected to intensity conversion by the amplifier 14 to α times. The first signal 17 of the horizontal section signal C1 whose intensity has been converted to β times by the amplifier 15 and the horizontal section signal C whose intensity has been converted to α times by the amplifier 14
The second signal 18 of 0 reaches the mixer 16, and the mixer 16 combines the signals to create a horizontal section signal C'0 of the 4: 2: 2 color signal 30 in the horizontal sections 2H to 3H. When this C′0 is expressed by an expression, C′0 = αC0 + βC1, which corresponds to the first expression of Expression 2.

In the next horizontal section 3H to 4H, the horizontal section signal C1 is input and similarly divided into a first signal 17 and a second signal 18, and the first signal 17 reaches the amplifier 15. The intensity of the first signal 17 that has reached the amplifier 15 is converted to δ times by the amplifier 15 this time.

In the horizontal sections 3H to 4H, the switch 12 is closed, and the second signal 18 input at this time is closed.
Is input to the memory 13. And at the same time, memory 1
3 outputs the second signal 18 of the horizontal section signal C0 delayed by two horizontal sections, and the amplifier 14 converts the intensity of the second signal 18 of the horizontal section signal C0 to γ times.

The first signal 17 of the horizontal section signal C1 whose intensity has been converted to δ by the amplifier 15 and the second signal 18 of the horizontal section signal C0 whose intensity has been converted to γ by the amplifier 14 are supplied to the mixer 16. And the mixer 16 combines the signals, and in the horizontal sections 3H-4H 4:
2: The horizontal section signal C′1 of the two-color signal 30 is created. When this C′1 is expressed by an expression, C′1 = γC0 + δC1, which corresponds to the second expression of Expression 2.

As described above, the 4: 2: 0 color signal 2
The horizontal section signal of 0 is input to the color signal vertical interpolation filter 10 twice per one horizontal section signal. The input horizontal signal is divided into a first signal 17 and a second signal
The signal is branched into a signal 18, and the first signal 17 is subjected to signal strength conversion by the amplifier 15. If the horizontal section at this time is the horizontal section in which the first horizontal section signal is input among the horizontal section signals of the 4: 2: 0 color signal 20 input twice, the amplifier 15 The signal strength conversion magnification is β times, and in the horizontal section where the second horizontal signal is input, the signal strength conversion magnification of the amplifier 15 is δ times.

As for the second signal 18, of the horizontal section signals of the 4: 2: 0 color signal 20 which are input twice each, when the horizontal section signal which is input first is input, the horizontal section is used. The second signal 18 is not input to the memory 13, and the memory 13 outputs the second signal 18 input to the memory 13 one horizontal section before. In the case of the horizontal section in which the second horizontal section signal is input, the second signal 18 is input to the memory 13, and at the same time, the second signal 18 input to the memory 13 two horizontal sections ago is output from the memory 13. Is output.

The second signal 18 output from the memory 13 reaches the amplifier 14, which converts the signal strength. The horizontal section at this time is the horizontal section in which the first horizontal section signal of the 4: 2: 0 color signal 20 input to the color signal vertical interpolation filter 10 is input twice. , The amplifier 14 outputs the second signal 1
8 is α-folded. If the horizontal section of the second 4: 2: 0 color signal 20 is a horizontal section, the amplifier 14 converts the intensity of the second signal 18 to γ times.

Then, the first signal 17 whose signal strength has been converted by the amplifier 15 and the second signal 18 whose signal strength has been converted by the amplifier 14 are combined by the mixer 16 to produce a 4: 2: 2 signal 30.

As described above, in the present embodiment, the color signal vertical interpolation filter 10 is connected to the switch 12, the memory 13, and the amplifier 1
4, an amplifier 15 and a mixer 16, and 4: 2:
Each horizontal section signal of the 0 color signal 20 is input to the color signal vertical interpolation filter 10 twice, and the input horizontal section signal is branched into a first signal 17 and a second signal 18, and the second signal 18 is converted into one horizontal signal. The input signal is input to the memory 13 at intervals, and the memory 13 reads out the input second signal 18 with a delay of two times, and converts the read second signal 18 and first signal 17 into signal intensities by the amplifiers 14 and 15. Since these signals are synthesized by the mixer 16 to create the 4: 2: 2 color signal 30, one signal can be obtained without using a plurality of delay lines.
The color signal vertical interpolation filter 10 can be configured with only one memory 13 and the circuit scale can be reduced.

Further, since the second signal 18 is input to the memory 13 every other horizontal section, the number of accesses to the memory 13 can be reduced, and the power consumption inside the circuit can be suppressed.

[0038]

As described above, according to the present invention, the color signal vertical interpolation filter is constituted by the switch means, one delay circuit, the first signal strength conversion means, the second signal strength conversion means, and the signal synthesis means. Then, each horizontal section signal of the 4: 2: 0 color signal is input twice to the color signal vertical interpolation filter, and the input horizontal section signal is branched into a first signal and a second signal. The delay signal is input to the delay circuit every horizontal section, and the delay circuit reads out the input second signal with a delay of two times, and reads the read second signal and the first signal into the second signal strength conversion means and the first signal. Signal strength conversion is performed by the strength conversion means, and those signals are synthesized by the signal synthesis means.
2: Since two-color signals are created, a color signal vertical interpolation filter can be configured with only one delay circuit without using a plurality of delay lines, and the circuit scale can be reduced.

Further, since the second signal is input to the delay circuit every other horizontal section, the number of accesses to the delay circuit can be reduced, thereby reducing the power consumption inside the circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a color signal vertical interpolation filter according to an embodiment of the present invention.

FIG. 2 shows a relationship between a 4: 2: 0 color signal input to a color signal vertical interpolation filter and a 4: 2: 2 color signal which is color signal vertically interpolated by the color signal vertical interpolation filter according to the embodiment of the present invention; FIG. 3 is a conceptual diagram showing a relationship.

FIG. 3 is a timing chart showing an operation of a color signal vertical interpolation filter according to the embodiment of the present invention.

FIG. 4 is a conceptual diagram showing a configuration of a 4: 2: 0 color signal.

FIG. 5 is a timing chart showing the operation of a conventional color signal vertical interpolation filter.

[Explanation of symbols]

10 ... color signal vertical interpolation filter, 11 ... branch point, 12 ... switch, 13 ... memory, 14 ...
・ Amplifier, 15 ・ ・ ・ Amplifier, 16 ・ ・ ・ Mixer, 20
... 4: 2: 0 color signal, 30 ... 4: 2: 2 color signal

Claims (4)

[Claims] 1. A color signal vertical interpolation filter for converting an input of a 4: 2: 0 color signal into an output of a 4: 2: 2 color signal, wherein the first color signal intensity of the input signal has two values. First signal strength conversion means for multiplying a constant by a constant, switch means for outputting an input signal every other horizontal section, and one delay for delaying the input signal output from the switch means for one horizontal section or two horizontal sections Circuit, and the color signal intensity of the input signal output from the delay circuit is 2
Second signal strength converting means for multiplying by a second constant having the same value, an input signal whose strength has been converted by the first signal strength converting means, and strength conversion by the second signal strength converting means. And a signal synthesizing means for synthesizing the input signal thus obtained. 2. The color signal vertical interpolation filter according to claim 1, wherein the input signal is input twice for each horizontal section signal. 3. A color signal vertical interpolation method for converting an input of a 4: 2: 0 color signal into an output of a 4: 2: 2 color signal, wherein the color signal intensity of the input signal has two values. The input signal is output every other horizontal interval, the input signal output every other horizontal interval is delayed by one horizontal interval or two horizontal intervals, and the color signal intensity of the delayed input signal is multiplied by a constant. Is multiplied by a second constant having two values, and an input signal multiplied by a constant by the first constant and an input signal multiplied by a constant by the second constant are synthesized. Color signal vertical interpolation method. 4. The color signal vertical interpolation method according to claim 3, wherein the input signal is input twice for each horizontal section signal.