JPH01260991A - Color video signal processing method - Google Patents

Abstract

PURPOSE:To attain information compression with very high compression rate without deteriorating picture quality by applying coding to two kinds of digital color difference signals subjected to line sequential processing for each block of (nXm) samples (n, m are integers being 2 or over) bridged over the lines with different color difference signals arranged thereupon. CONSTITUTION:A coding circuit 12 applies block coding to data read out of a block processing circuit 10 and reduce information quantity (bit number per picture element) and outputted. The color difference signal subjected to line sequential processing is fed to a block processing circuit 23 and arranged for each block similarly to the case with the block processing circuit and the result is fed to a code processing circuit 25. The line sequential color difference signal subjected to block coding by the circuit 25 is subjected to time base multiplex with a luminance signal subjected to block coding by a multiplex circuit 30 and the result is sent to a transmission line such as communication equipment, magnetic recording and reproducing device via a terminal 32.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color video signal processing method, and more particularly to a color video signal processing method that performs high efficiency encoding.

[Prior Art] Generally, in a color video signal consisting of a luminance signal and two types of color difference signals, the band of the color difference signal is narrower than that of the luminance signal, and the sampling frequency during digitization also differs from that of the luminance signal. The sampling frequency will be set to about the sampling frequency of the station.

Furthermore, considering the visual characteristics on the screen, it is not noticeable even if the amount of information of the color signal is further compressed compared to the amount of information of the luminance signal. However, simply lowering the sampling frequency of the color difference signal further will result in a noticeable decrease in resolution in the horizontal direction.

Therefore, conventionally two types of color difference signals (CN.

It has been proposed to expand the amount of information by line-sequentializing the image data (co), or to spread out the amount of information by using an offset Sarasan printer that transmits pixels shifted between lines or fields and thins out other pixels.

On the other hand, in recent years video signals have become even more high-definition, with the number of scanning lines decreasing to 1.
000 or more so-called high quality (formerly Definition)
Television signals are also being tested. Therefore, the amount of information in video signals tends to further increase, and when the limit of the transmission speed of the transmission path is taken into account, the amount of information must be further compressed, and various high-efficiency encoding methods have been proposed.

As an example of this high-efficiency encoding method, one screen is (n×
There is block encoding in which information is divided into encoding blocks each consisting of m) sample points and the correlation between each pixel in each block is used to compress information without deteriorating image quality. This block encoding is advantageous in that the deterioration in image quality is small because encoding can be performed using pixels with the highest correlation, and the propagation of code errors can be suppressed only within each clock.

[Problems to be solved by the invention] Therefore, the present invention provides efficient block encoding for the two types of color difference signals when transmitting or recording/reproducing a component video signal consisting of two types of color difference signals and a luminance signal. This paper aims to present a novel color video signal processing method that can perform the following steps.

[Means for Solving the Problems] With this objective in mind, in the color video signal processing method of the present invention, two types of line-sequential digital color difference signals are arranged into different color difference signals. Encoding is performed for each block of (n×m) samples (n and m are each an integer of 2 or more) spanning the line.

[Operations] By doing the above, the color difference signal whose information has been compressed by line sequentialization is subjected to block encoding, so the compression rate is extremely high and the encoding block can be set small relative to the number of pixels. It is possible to encode color difference signals without significant deterioration in image quality.

[Example] Examples of the present invention will be described below.

FIG. 1 is a diagram showing a schematic configuration of a color video signal transmission system as an embodiment of the method of the present invention. 2 in the diagram
4.6 is the input terminal for the luminance signal (Y), and 4.6 is the input terminal for the color difference signal (Y), respectively.
c,, CW> input terminal. The input luminance signal ci is sampled by the A/D converter 8 and input to the blocking circuit IO. The blocking circuit 10 is a circuit that reads out a digital luminance signal in raster scanning order for each block of (4×4) pixels.

Figure 2 is a diagram for explaining the operation of the blocking circuit.
In the figure, the solid lines indicate the scanning lines of the first field, the broken lines indicate the scanning lines of the second field, and the dashed-dotted lines indicate clock boundaries. That is, the blocking circuit 10 has the pixel numbers shown in circles: l→2→3→4→17→18→19→20→...→9
→lO→11→12→25→26→27→28→・・・
The data input in the order of l → 2 → 3 → 4 → 5 → 6 → 7
Output in the order of →8→9→...

The encoding circuit 12 performs block encoding on the data read out from the blocking circuit 10 to reduce the amount of information (the number of bits per pixel) and then outputs the data.

On the other hand, the color difference signals Cs and C input from the input terminals 4 and 6
Each of w is converted into a digital signal by A/D converters 14 and 16 using a sampling clock of the frequency of the luminance signal. The digitized color difference signals C,,C, are supplied to the next stage prefilter 15.17, where the vertical frequency is limited. The color difference signals C,,C, output from the prefilter 15.17 are output from the switching control circuit 19.
Switch 21 according to the rectangular wave that is inverted every horizontal scanning period.
is line sequentialized.

The color difference signal CN on the screen in this line-sequential signal
, C, is shown in FIG. In the figure, the solid lines indicate the scanning lines of the first field, and the broken lines indicate the scanning lines of the second field, and as shown in the figure, C, . . . Cw are arranged in units of two lines in each frame.

The line sequential color difference signals C,,C, are sent to the blocking circuit 2.
3, the arrangement is converted every clock as in the case of the blocking circuit, and the signal is supplied to the encoding circuit 25. This encoding circuit 25 also performs encoding using the horizontal pixel spacing or the correlation within the encoding block of (4×4) pixels, which is different from that of the luminance signal. At this time, if blocks are taken as shown in FIG. 2, if each pixel in the line including pixels 1 and 5 is 00, each pixel in the line including pixels 9 and 13 becomes C2.

The line-sequential color difference signal that has been block-coded by the encoding circuit 25 is time-axis multiplexed by the multiplexing circuit 30 with the block-coded luminance signal, and is sent to a transmission line 34 of a communication device, magnetic recording/reproducing device, etc. via a terminal 32. Sent out.

An example of the configuration of the prefilter in the above system is shown in FIG. In the figure, 101 is an input terminal.

102.103 is 1 horizontal scanning period (IH) delay circuit, 1
04, 105, 107 are station coefficient units, 106 is an adder, 1
08 is an output terminal. This pre-filter limits the maximum frequency in the vertical direction to just a few.

Note that block encoding methods include, for example, orthogonal transform encoding, vector quantization, and encoding that transmits a quantization index obtained by linearly quantizing the maximum value and minimum value within a block and each pixel between them. , an encoding method using correlation within a block can be applied.

According to the above-described configuration, information can be compressed at a high compression rate by block encoding a line-sequential color difference signal. Furthermore, it is generally known that there is a high correlation between two types of color difference signals C, , c, and highly efficient encoding is possible by keeping the size of the encoding block small. Furthermore, if one coded block is to be reproduced, two types of color difference signals C, , C are used.

Therefore, if this encoding process is applied to a digital VTR, it is possible to restore color even when performing a so-called high-speed search.
It can be said that this process is very suitable for R.

Next, the decoding system will be explained.

The color video signal via the transmission path 34 is supplied to a separation circuit 38 via a terminal 36 and is separated into a luminance signal and a line-sequential color difference signal. These are respectively flock decoding circuits 40
．． 43 and encoder circuits 12, 25 . It is decoded by the reverse process to restore the original amount of information. The decoded luminance signal and line-sequential color difference signal are each converted into a rasterization circuit from block order to scanning line order.

The rasterized line-sequential color difference signal is supplied to the B input of the switch 53 and the A input of the switch 55. The switching control circuit 50 supplies a rectangular wave that is inverted every l horizontal scanning period to the switches 53 and 55, and supplies the CN of the line-sequential color difference signal output from the rasterization circuit 49 to the interpolation filter 57.
Cw is supplied to an interpolation filter 59. At this time, the interpolation filter 57 is supplied with all "0" data corresponding to the 0 level during the horizontal scanning period in which CN does not exist, and the interpolation filter 59 is supplied with all "0" data corresponding to the O level in the horizontal scanning period in which Cw does not exist. Data of “0” is supplied.

The configuration of the interpolation filters 57 and 59 is the same as that of the filter shown in Fig. 4, but since the data of one of the two lines or the data corresponding to the O level is substituted, at this point, the average level or the data attenuated to the station. Therefore, the coefficient unit 107 becomes unnecessary. The interpolation filters 57 and 59 convert the line sequential signals into two types of color difference signals C, , Cw. These are input to D/A converters 58 and 60, respectively, and the luminance signal is output from the rasterization circuit 46 or sent directly to the D/A converter 58.
6. At this time, the operating frequency of the D/A converter 56 is four times that of the D/A converter 58.60, and these
The luminance signals and color difference signals C, 4, and Cw converted into analog signals by the /A converters 56, 58, and 60 are outputted from terminals 62.about.64.66 as component color video signals.

In addition, the size of the encoded block in the above embodiment is (4
X4) Did you explain the case of pixels? - In general, the same effect can be obtained with (n×m) pixels (n≧2.m≧2), and the values of these n and m depend on the encoding method and data. This can be arbitrarily determined depending on the compression ratio requirements and the like.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a color video signal processing method capable of compressing information at an extremely high compression ratio without deteriorating the image quality of color difference signals.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a color video signal transmission system as an embodiment of the method of the present invention, FIG. 2 is a diagram for explaining the operation of the blocking circuit in FIG. 1, and FIG. 4 is a diagram showing the arrangement of each color difference signal on the screen of line-sequential signals, and FIG. 4 is a diagram showing the configuration of the front filter in FIG. 1. In the figure 4.6...Color difference signal input terminal 21...Switch 23...Blocking circuit 25...Block encoding circuit

Claims (1)

[Claims] Two types of line-sequential digital color difference signals are encoded for each block of (n×m) samples (n and m are integers of 2 or more) spanning lines with different color difference signals. Color video signal processing method.