JP2952875B2 - Decoding device and method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoding device for decoding coded data in which each pixel is coded in a digital image signal in units of a pixel block including a plurality of pixels, and a decoding apparatus therefor. About the method.

[Conventional technology]

As a method of compressing a transmission band of an image signal, specifically, a television signal, one image is divided into pixel blocks each including a predetermined number of pixels, and the range of the maximum value and the minimum value of the pixel data in the pixel block is determined. Is divided into a predetermined number of sections, and an encoding method for converting each pixel data into a code (hereinafter, referred to as a divided value) indicating the section to which the pixel data belongs is known. In this manner, for each pixel block, any two data of the maximum value, the minimum value, and the difference (dynamic range) thereof, and the decomposition value data for each pixel are transmitted.

FIG. 2 is a schematic block diagram of a conventional example of an image transmission apparatus for normalizing each pixel data by a maximum value and a minimum value and transmitting the divided value data. It is assumed that the image data handled here is quantized at 8 bits per sample. Digital image data is input to the input terminal 10 in the order of normal horizontal scanning lines, and the pixel
Reference numeral 12 divides an image of one frame or one field into pixel blocks each including m pixels in a vertical direction (vertical direction) and n pixels in a horizontal direction (horizontal direction), and sequentially outputs constituent pixel data for each pixel block.

The maximum value detector 14 detects a maximum value from m × n pixels in each pixel block, and the minimum value detector 16 detects a minimum value. The timing adjustment circuit 18 delays the output of the blocking circuit 12 by a time corresponding to the detection work time in the maximum value detector 14 and the minimum value detector 16, and outputs pixel data in a predetermined order for each pixel block. . Split value conversion circuit 20
Outputs a division value (k bits) indicating to which division section each pixel data belongs when the ^2k division is performed between the maximum value of the maximum value detector 14 and the minimum value of the minimum value detector 16 I do. k
Is, for example, about 3.

22, 24 and 26 are parallel-serial converters for converting parallel data into serial data. Switch 30
Are connected in the order of b, c, a contacts under the control of the timing control circuit 32. That is, the maximum value data, the minimum value data, and the divided value data of each pixel are applied to the FIFO type buffer 34 in this order by the switch 30. The buffer 34 is provided for adjusting the transmission bit rate. The synchronization adding circuit 36 adds a synchronization code to the head of the data string from the buffer 36, and sends the data from an output terminal 38 to a transmission path or a recording medium. The timing control circuit 34
Controls the operation timing of each circuit other than the switch 30.

If m and n are 4 and k is 3, the data amount of one pixel block is 128 bits (= 8 bits × 16), but this encoding results in 64 bits (= 8 + 8 + 3 × 16).
Can be compressed to 1/2.

[Problems to be solved by the invention]

However, in this encoding method, pixel data is once normalized in a dynamic range, and the normalized data is compression-encoded. Therefore, for decoding, information on the dynamic range is indispensable for each pixel block. . For example, if the maximum value and minimum value data are transmitted together with the compression code (division value) of each pixel, if any transmission error occurs in the maximum value data or the minimum value data, the image data is restored for that pixel block. become unable.

Therefore, an object of the present invention is to provide a decoding apparatus and method capable of restoring an image of a pixel block as much as possible even when an error occurs in encoded data encoded in pixel block units.

[Means for solving the problem]

A decoding device according to the present invention divides a digital image signal into pixel blocks each including a plurality of pixels, performs block coding in units of the pixel blocks, and encodes first and second data having a predetermined relationship in encoded data. 2. A block encoding decoding apparatus including the first data and the second data, wherein the first data and the second data are transmitted in a predetermined order, and input means for inputting the encoded data. Comparing a value related to the first data and a value related to the second data in the encoded data input by the input unit, based on whether the pixel data has the predetermined relationship or not. Determining means for determining whether or not there is an error; and an interpolation image obtained by using data of a pixel having a high correlation with the pixel for a pixel in the pixel block determined to have an error by the determining means. And having a replacement means for replacing the data.

A decoding method according to the present invention divides a digital image signal into pixel blocks each including a plurality of pixels, performs block coding in units of the pixel blocks, and encodes first and second data having a predetermined relationship in encoded data. 2. A block coding decoding method comprising transmitting the first data and the second data in a predetermined order, the data including the first data and the second data. The value of the first data and the value of the second data in the encoded data are compared to determine whether or not there is an error in the pixel block unit depending on whether or not the predetermined relationship exists. And replacing the pixels in the pixel block determined to be erroneous by the determination result with interpolation pixel data obtained using data of pixels having high correlation with the pixels.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and is functionally a receiving device corresponding to the transmitting device of FIG. Here, it is assumed that the maximum value data is always promised to be input before the minimum value data.

In FIG. 1, the input terminal 40 is connected to the output terminal 38 of FIG.
Is input via a transmission path.
The code string of the input terminal 40 is a switch 42 and a sync separation circuit.
The sync separation circuit 44 separates the sync code and applies it to the timing control circuit 46. Timing control circuit
46 controls the operation timing of each of the illustrated circuits, including switching of the switch 42, based on the synchronization code. By switching the switch 42, the maximum value MAX and the minimum value MIN are changed from the contact a to the serial / parallel (S / P) converter 48, and the divided value code is set to b.
The voltage is applied to the S / P converter 50 from the contact point. First code of the output of S / P converter 48 (Maximum value if no error)
Is latched by the maximum value latch circuit 52, and the next code (the minimum value MIN if there is no error) is the minimum value latch circuit 5.
Latched to 4. The latch circuits 52 and 54 output the maximum value and the maximum value, respectively, until the maximum value and the minimum value of the next pixel block are input.
Keep the minimum value.

The divided value inverse conversion circuit 56 converts the output (divided value data) of the S / P converter 50 into a representative value of each divided region with reference to the maximum value and the minimum value latched by the latch circuits 52 and 54. Output. The scan converter 58 includes a split value inverse conversion circuit 56.
Is converted into a raster scan.

The determination circuit 60 checks whether the output of the maximum value latch circuit 52 is larger than the output of the minimum value latch circuit 54. That is,
When the output of the maximum value latch circuit 52 is smaller than the output of the minimum value latch circuit 54, it can be estimated that a transmission error has occurred in the maximum value or the minimum value. The determination signal from the determination circuit 60 is time-adjusted by the timing adjustment circuit 62 and then applied to the scan converter 64. The scan converter 64 converts the determination signal into a signal indicating the screen position in the raster scan of the pixel data included in the corresponding pixel block. And scan converter
The switch 64 connects the switch 66 to the contact a for the pixel of the pixel block without error, and connects the switch 66 to the contact b for the pixel of the pixel block with error.

That is, the switch 66 determines whether the pixel of the pixel block in which an error has occurred is a screen immediately before the frame memory (or
Further, the image signal is replaced by the previous image signal. Therefore, output terminal 70
From, when there is no error, a signal of a restored image from the received data is obtained, and when there is an error, an image signal modified and supplemented with the image of one frame before is obtained. The output of the switch 66 is input to the frame memory 68, whereby the image stored in the frame memory is updated.

In this embodiment, the case where the maximum value and the minimum value data are transmitted as the dynamic range information is taken as an example, but the present invention is not limited to this. In addition, even in the case of a transmission method that performs vector quantization after division value conversion and other transmission methods, a transmission method that can confirm a transmission error under some regularity has a rule based on the rule. By checking the consistency, the presence / absence of an error can be determined uniformly, so that the previous screen can be used alternately according to the result of this determination. Note that in the above embodiment, a pixel having a strong correlation is
Although the pixel of the previous screen is selected and the data of this pixel is directly used as the interpolation data, the interpolation pixel data may be obtained by using the pixel of the subsequent screen or the pixel of the adjacent pixel block.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, when an error occurs in the decoded encoded data, it can be detected without adding redundant data such as an error correction check code, and the error can be detected. Since the pixels in the partial pixel block are replaced with the interpolated pixel data obtained from the pixels having a high correlation, the transmission error becomes stronger and the image quality deterioration due to the transmission error can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention, and FIG. 2 is a configuration block diagram of an image transmission device. 40: input terminal, 44: synchronization separation circuit, 46: timing control circuit, 52: maximum value latch circuit, 54: minimum value latch circuit, 56: split value inverse conversion circuit, 58, 64 ... Scan converter, 60: Judgment circuit, 68: Frame memory, 70: Output terminal

Claims (2)

(57) [Claims] 1. A digital image signal is divided into pixel blocks each including a plurality of pixels, and block encoding is performed in units of the pixel blocks. The encoded data includes first data and second data having a predetermined relationship. A block encoding decoding device that transmits the first data and the second data in a predetermined order, comprising: input means for inputting the encoded data; and the input means And comparing the value of the first data and the value of the second data in the coded data input according to whether there is an error in the pixel block unit depending on whether or not the predetermined relationship exists. Determination means for determining whether or not there is an error; and for pixels in the pixel block determined to be erroneous by the determination means, interpolated pixel data obtained using data of pixels having high correlation with the pixels. Decoding apparatus characterized by having a substitution means for. 2. A digital image signal is divided into pixel blocks each consisting of a plurality of pixels, and is block-coded in units of the pixel blocks. First and second data having a predetermined relationship are included in the coded data. And a block encoding decoding method for transmitting the first data and the second data in a predetermined order, wherein the encoded data is inputted, and the inputted encoding is performed. Comparing the value of the first data in the data and the value of the second data to determine whether there is an error in the pixel block unit depending on whether or not having the predetermined relationship; A decoding method comprising: replacing a pixel in a pixel block determined as having an error based on the determination result with interpolation pixel data obtained using data of a pixel having a high correlation with the pixel.