JP2013219611A - Encoder and encoding method, and decoder and decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an appropriate compression coding of image data having different images alternately on every other line.SOLUTION: A decoding prediction error is generated by compressing and expanding a prediction error which is a prediction error of an encoding object pixel X, and is added to a prediction value which is outputted from a prediction pixel selection part, for generating a prediction value of the pixel X. A storage part stores a first prediction value of the pixel X, a second prediction value of a left neighbor pixel of the pixel X on a line which includes the pixel X, and a third prediction value of a plurality of pixels close to the pixel X included in a line just before the current line in coding order. In a case of general image coding, a prediction mode is selected based on the first, second, and third pixels stored in the storage part, and a prediction value is selected within the storage part by a prediction pixel selection part, according to the selected prediction value. In a case of LBL system image coding, the prediction mode is forcibly set to "Left", and the prediction pixel selection part selects the second prediction value in the storage part and outputs it.

Description

  The present invention relates to an encoding device and an encoding method, and a decoding device and a decoding method suitable for use in compression encoding image data.

  In recent years, with the spread of digital high-definition broadcasts and HD (High Definition) image recording devices, and the higher resolution of digital cameras, the size and resolution of television receivers used at home has increased. It is out. For this reason, as for LSI (Large-Scale Integration) that performs image processing in a television receiver, the demand for LSIs that support HD images (1920 pixels × 1080 lines) is increasing.

  By the way, in image processing, enhancer, frame rate conversion processing, etc. needs to store image data of one frame or more in a memory capable of high-speed access such as DDR SDRAM (Double-Data-Rate Synchronous Dynamic Random Access Memory). is there. Such a memory for storing image data is expensive because high-speed access is required, and a plurality of large-capacity memories are used to store a plurality of frames of the above-described HD image data. In some cases, it is necessary to increase the product cost and the number of parts.

  Therefore, a technique for compressing and encoding image data and storing it in a memory has been conventionally developed. The MPEG (Moving Pictures Experts Group) method is known as one of the compression coding methods of image data. However, since the algorithm is complicated, it takes up a large area when the circuit is made into an LSI. It is not suitable for application to a signal processing LSI specialized in high image quality processing or an inexpensive image processing LSI. In Patent Document 1, prior to encoding of a pixel to be encoded, the pixel to be encoded is one-dimensionally using pixel values of pixels that are adjacent to the pixel to be encoded in the line direction and have already been encoded. A method of performing compression encoding by predicting the pixel value of is disclosed.

  Further, with respect to the line including the encoding target pixel, the pixel value of the pixel corresponding to the encoding target pixel and the neighboring pixels of the line immediately before in the encoding order is further used in two dimensions. A method of performing compression encoding by predicting a pixel value of a pixel to be encoded is also known. By using this method of predicting pixel values in two dimensions, it is possible to improve the encoding efficiency compared to the case of predicting pixel values in one dimension.

  By the way, in recent years, a technique related to so-called 3D video that shows a two-dimensional image stereoscopically has been developed, and an apparatus for supplying 3D video has also become widespread. As one of 3D video transmission formats, there is an LBL (Line-by-Line) system in which video signals for right eye and left eye are alternately arranged every other line.

Japanese Patent Laid-Open No. 7-15347

  In the LBL method, it is considered that the correlation between adjacent lines is small with respect to a general video. Therefore, when the above-described compression encoding method for predicting pixel values in two dimensions is applied to a video signal based on the LBL method, if the prediction direction is determined at a position other than the encoding target pixel position, the prediction direction is actually encoded. There may be a case in which the prediction error is different from the prediction direction in which the prediction error is minimized at the target pixel position. In this case, the prediction error in the vertical direction may increase, and in some cases, the prediction error may propagate downward.

  The present invention has been made in view of the above, and an object of the present invention is to appropriately compress and encode image data in which different images are arranged alternately for each line.

  In order to solve the above-described problem and achieve the object, the first invention acquires a prediction error that is an error between a pixel value of an input pixel and a first prediction value obtained by predicting the pixel value. A compression unit that compresses the prediction error, a decompression unit that decompresses the prediction error compressed by the compression unit, a prediction error decompressed by the decompression unit, and the first prediction value, An adder for generating a prediction value; at least a second prediction value; and a third line corresponding to a pixel adjacent to the input pixel in the previous line in the coding order with respect to the line including the input pixel A storage unit that stores a prediction value and a fourth prediction value corresponding to the pixel immediately before the input pixel in the encoding order; a second prediction value; a third prediction value; A predicted value output unit that outputs a first predicted value obtained based on at least two predicted values of The value output unit obtains the first predicted value based on the second predicted value and the fourth predicted value when a predetermined control signal is received, and receives the second predicted value when the control signal is not received. The first predicted value is obtained based on the predicted value, the third predicted value, and the fourth predicted value.

  Further, the second invention is a prediction error acquisition step for acquiring a prediction error that is an error between the pixel value of the input pixel and the first prediction value for which the pixel value is predicted, a compression step for compressing the prediction error, An expansion step for expanding the prediction error compressed by the compression step, an addition step for adding the prediction error expanded by the expansion step and the first prediction value to generate a second prediction value, and at least a first 2 prediction values, a third prediction value corresponding to a pixel close to the input pixel in a line immediately preceding in the encoding order with respect to the line including the input pixel, and an encoding order with respect to the input pixel The storage step of storing the fourth prediction value corresponding to the previous pixel in the storage unit, the second prediction value stored in the storage unit, the third prediction value, and the fourth prediction value And the first prediction obtained based on at least two prediction values. A predicted value output step for outputting a value, and the predicted value output step receives the first control value based on the second predicted value and the fourth predicted value when a predetermined control signal is received. When the control signal is not received, the first predicted value is obtained based on the second predicted value, the third predicted value, and the fourth predicted value.

  In addition, the third invention expands an output obtained by compressing and encoding a prediction error that is an error between the pixel value of the input pixel and the first prediction value obtained by predicting the pixel value, To generate a second predicted value. When a predetermined control signal is not received, the second predicted value and the line including the input pixel are preceded by the coding order. The first predicted value is calculated based on the third predicted value corresponding to the pixel adjacent to the input pixel in the line and the fourth predicted value corresponding to the pixel preceding by one in the encoding order with respect to the input pixel. When a predetermined control signal is received, a first prediction value is obtained based on the second prediction value and the fourth prediction value, and a decoding process is performed on the compressed prediction error obtained by compression-coding the prediction error. A decoding device that performs decompression on the compression prediction error and decompression on the compression prediction error decompressed by the decompression unit. An adder that adds the decoded prediction values and outputs the result as a first decoded pixel; a first decoded pixel; and a first of the previous line in decoding order with respect to the line that includes the first decoded pixel A decoded prediction value obtained based on at least two decoded pixels of the second decoded pixel adjacent to the first decoded pixel and the third decoded pixel immediately preceding the first decoded pixel in the decoding order is output A predicted value output unit that obtains a decoded predicted value based on the first decoded pixel and the third decoded pixel when receiving a predetermined control signal, and the control signal output unit In a case where the received decoding value is not received, a decoded prediction value is obtained based on the first decoded pixel, the second decoded pixel, and the third decoded pixel.

  According to a fourth aspect of the present invention, an output obtained by compressing and encoding a prediction error, which is an error between a pixel value of an input pixel and a first prediction value obtained by predicting the pixel value, is expanded, the expanded prediction error, To generate a second predicted value. When a predetermined control signal is not received, the second predicted value and the line including the input pixel are preceded by the coding order. The first predicted value is calculated based on the third predicted value corresponding to the pixel adjacent to the input pixel in the line and the fourth predicted value corresponding to the pixel preceding by one in the encoding order with respect to the input pixel. When a predetermined control signal is received, a first prediction value is obtained based on the second prediction value and the fourth prediction value, and a decoding process is performed on the compressed prediction error obtained by compression-coding the prediction error. A decompression step for decompressing a compression prediction error, and a decompression step performed by the decompression step. An addition step of adding a decoded prediction value to a prediction error and outputting the result as a first decoded pixel, a first decoded pixel, and a line including the first decoded pixel, one line before the decoding order. Calculated based on at least two decoded pixels of the second decoded pixel adjacent to the first decoded pixel in the line and the third decoded pixel immediately preceding the first decoded pixel in the decoding order. A predicted value output step for outputting a decoded predicted value, and the predicted value output step receives a decoded control value based on the first decoded pixel and the third decoded pixel when a predetermined control signal is received. When the control signal is not received, a decoded prediction value is obtained based on the first decoded pixel, the second decoded pixel, and the third decoded pixel.

  According to the present invention, there is an effect that image data in which different images are alternately arranged for each line can be appropriately compressed and encoded.

FIG. 1 is a block diagram schematically showing an exemplary configuration of an encoding apparatus applicable to each embodiment. FIG. 2 is a diagram illustrating an exemplary configuration of a packet generated by the output processing unit. FIG. 3 is a diagram for explaining the relationship between the state of the signal first_word and the output of the output processing unit. FIG. 4 is a block diagram schematically showing a configuration of an example of a decoding device applicable to each embodiment. FIG. 5 is a block diagram illustrating a configuration of an example of an encoding unit that performs an encoding process based on one-dimensional prediction. FIG. 6 is a block diagram illustrating a configuration of an example of a decoding unit that performs decoding processing of encoded data encoded using a one-dimensional prediction process. FIG. 7 is a diagram for more specifically explaining the two-dimensional prediction process. FIG. 8 is a block diagram illustrating a configuration of an example of a known encoding unit for performing an encoding process using a two-dimensional prediction process. FIG. 9 is a diagram illustrating an example of a signal output from the encoding device. FIG. 10 is a block diagram illustrating a configuration of an example of a known decoding unit that performs a decoding process of encoded data encoded using a two-dimensional prediction process. FIG. 11 is a block diagram illustrating an exemplary configuration of the encoding unit according to the first embodiment. FIG. 12 is a block diagram illustrating an exemplary configuration of the decoding unit according to the first embodiment. FIG. 13 is a block diagram illustrating a configuration of an example of an image processing apparatus according to the second embodiment.

  Exemplary embodiments of an encoding device, an encoding method, and a decoding device and a decoding method will be described below in detail with reference to the accompanying drawings. FIG. 1 schematically shows a configuration of an example of an encoding apparatus 1 applicable to each embodiment. The encoding device 1 encodes image data, and includes an input processing unit 10, an encoding unit 11, and an output processing unit 12.

  Pixel data is sequentially input as input image data to the encoding device 1. The input processing unit 10 divides the input pixel data of one line for each predetermined number of pixels to form a pixel block. The input processing unit 10 outputs a signal first_word indicating the timing of the top pixel data of the pixel block (not shown). The signal first_word is a signal that is set to a high state at the timing of the top pixel data of the pixel block and is set to a low state at other timings.

  The pixel block output from the input processing unit 10 is supplied to the encoding unit 11, and pixel data included in the pixel block is encoded by a predetermined encoding method. The encoded data obtained by encoding the pixel data in the encoding unit 11 is supplied to the output processing unit 12. The output processing unit 12 has a memory, packs the supplied encoded data into a packet of a predetermined size using the memory, and outputs the packet as an encoded block.

  FIG. 2 shows an exemplary configuration of a packet generated by the output processing unit 12. In this example, the packet has a data length of T bits having a predetermined size as a whole. For example, a coding block is held in a storage element such as a flip-flop (Flip Flop) included in the output processing unit 12 to form a packet. At this time, the head of the encoded block shown on the right side of FIG. 2 is the least significant bit LSB (Least Significant Bit), and the rear end of the encoded block shown on the left side of FIG. 2 is the most significant bit MSB (Most Significant Bit). .

  Data D0 having a data length of N bits is packed from a predetermined position in the encoded block. In this example, data D0 is packed from the LSB side of the encoded block. As the data D0, the pixel data at the head of the line is used as it is as the original pixel data according to the state of the signal first_word. This original pixel data is pixel data that serves as a reference at the time of decoding.

  From the next to the data D0, as illustrated as encoded data C1, C2,..., C (i-2), C (i-1) obtained by encoding pixel data, the codes are sequentially encoded toward the MSB side. It will be packed in the block. The encoded data C1, C2,..., C (i-2), C (i-1) each have a data length of M bits (M <N). In the most significant bit MSB of the encoded block, an area F including a 1-bit control signal is arranged, and the data amount of the entire packet is T bits.

  The relationship between the state of the signal first_word and the output of the output processing unit 12 will be described with reference to FIG. FIG. 3A shows a clock. For example, one pixel data is input to the encoding unit 11 for each clock. FIG. 3B shows the state of the signal first_word. FIG. 3C shows encoded data output from the output processing unit 12 after being packed into a packet.

  The signal first_word is in a high state for a period of one pixel data from the beginning of each packet # 1, # 2,... Output from the output processing unit 12, and is in a low state in other periods. When the signal first_word is in the high state, the original pixel data is output from the encoding unit 11, and this original pixel data is used as the data D0 and packed at the head of each packet # 1, # 2,.

  On the other hand, when the signal first_word is in the low state, the encoded data obtained by encoding the pixel data is output from the encoding unit 11. This encoded data is illustrated as encoded data C1, C2,..., C (i-2), C (i-1) in FIG. 2 from the next of the data D0 in each packet # 1, # 2,. As shown in the figure, it is sequentially packed toward the MSB side.

  FIG. 4 schematically shows a configuration of an example of a decoding device 2 applicable to each embodiment. The decoding device 2 decodes the image data encoded by the encoding device 1 described above, and includes an input processing unit 20, a decoding unit 21, and an output processing unit 22. Packets # 1, # 2,... Configured as described with reference to FIG.

  The input processing unit 20 cuts out the encoded data D0, C1, C2,..., C (i-2), C (i-1) from the input packet and sequentially supplies them to the decoding unit 21. At this time, when each packet # 1, # 2,... Is input, the input processing unit 20 sets the signal first_word to the high state corresponding to each head data D0, and when the output of the head data D0 is completed, Set first_word to the low state. Further, the input processing unit 20 extracts a control signal from the region F of the most significant bit MSB of each packet # 1, # 2,. The input processing unit 20 supplies the signal first_word and the control signal to the decoding unit 21.

  The decoding unit 21 decodes the encoded data supplied from the input processing unit 20 and outputs decoded data. At this time, if the signal first_word is in a high state, the decoding unit 21 outputs the encoded data D0 as it is as decoded data, assuming that the encoded data D0 is supplied. If the signal first_word is in the low state, the encoded data C1, C2,..., C (i-2), C (i-1) are supplied and decoded by a predetermined method, and the decoded data is output. To do.

  The output processing unit 22 shapes the decoded data output from the decoding unit 21 into a predetermined format, and outputs the output data from the decoding device 2 as output data.

(First example of known encoding process)
Here, in order to facilitate understanding, a first example of an encoding process that is a premise of the encoding unit 11 according to the embodiment will be described. First, a description will be given of an encoding process in which encoding is performed by obtaining a prediction value in one dimension using information on pixels adjacent to the encoding target pixel on the line. FIG. 5 illustrates an exemplary configuration of an encoding unit 11A that performs an encoding process based on one-dimensional prediction. The encoding unit 11A includes a subtractor 100, a prediction error compression unit 101, an output selector 102, and a prediction unit 103. In addition, the prediction unit 103 includes a prediction error expansion unit 110, an adder 111, a prediction value selector 112, and a storage unit 113.

  The operation of the encoding unit 11A will be described. The encoding target pixel data output from the input processing unit 10 is sequentially input to the encoding unit 11A, for example, according to a clock. The encoding target pixel data is input to the subtracted input terminal of the subtracter 100, the selection input terminal 102A of the output selector 102, and the selection input terminal 112A of the prediction value selector 112, respectively. A prediction value output in units of pixels from the prediction unit 103 is input to the subtraction input terminal of the subtracter 100. The subtracter 100 subtracts the prediction value from the pixel value of the pixel data (hereinafter simply referred to as pixel data), outputs a prediction error value, and supplies the prediction error compression unit 101 to the prediction error value.

  The prediction error compression unit 101 compresses the prediction error value by a predetermined compression method, and reduces the data amount. For example, the prediction error compression unit 101 quantizes the prediction error value according to a predetermined quantization table, and compresses the data amount of the prediction error value. The compressed prediction error value is supplied to the prediction error expansion unit 110 of the prediction unit 103 and is input to the selection input terminal 102B of the output selector 102.

  The output selector 102 selects one of the selected input terminals 102A and 102B according to the value of the signal first_word supplied from the input processing unit 10, and uses the data input to the selected input terminal as encoded data. Output from the encoding unit 11A. For example, if the signal first_word is in a high state, the output selector 102 selects the selection input terminal 102A, and outputs the input encoding target pixel data as encoded data as the original pixel data. On the other hand, the output selector 102 selects the selection input terminal 102B, for example, if the signal first_word is in a low state, and outputs the compressed prediction error value as encoded data.

  The prediction error decompression unit 110 decompresses the compressed prediction error value obtained by compressing the prediction error value in the prediction error compression unit 101 according to the inverse quantization table corresponding to the quantization table used in the prediction error compression unit 101, and before compression. A restored prediction error value obtained by restoring the prediction error value of is output. The restoration prediction error value is input to one input terminal of the adder 111. The adder 111 adds the restored prediction error value input to one input terminal and the predicted value output after being delayed by one pixel from the storage unit 113 described later, and adds the added value to the predicted value selector 112. Input to the selection input terminal 112B. The addition value output from the adder 111 is a decoded value obtained by decoding the compressed prediction error value output from the prediction error compression unit 101.

  The prediction value selector 112 selects one of the selection input terminals 112A and 112B in accordance with the value of the signal first_word, and the compressed prediction output from the prediction error compression unit 101 is input to the data input to the selected input terminal. The error value is output as a decoded value. For example, if the signal first_word is in a high state, the prediction value selector 112 selects the selection input terminal 112A, and outputs the encoding target pixel data as the decoded value. On the other hand, if the signal first_word is in the low state, the prediction value selector 112 selects the selection input terminal 112B and outputs the decoded value output from the adder 111.

  The decoded value output from the predicted value selector 112 is supplied to the storage unit 113. The storage unit 113 is a buffer memory, for example, and holds the supplied decoded value. The decoded value held in the storage unit 113 is delayed by one pixel, and is stored as a predicted value for decoding the encoded data obtained by encoding the encoding target pixel data and predicting the value of the encoding target pixel data. 113 is output. The predicted value output from the storage unit 113 is input to the subtraction input terminal of the subtracter 100 and is input to the other input terminal of the adder 111.

  As described above, the encoding unit 11A performs prediction error compression on the prediction error value of the encoding target pixel data with respect to the prediction value based on the previous encoding target pixel data in the encoding order of the encoding target pixel data. The data is compressed by the unit 101 and output as encoded data.

  At this time, the signal first_word is set to the high state at the timing of the top pixel data of the pixel block based on the encoding target pixel data, and the signal first_word is set to the low state at other timings. As a result, for each pixel data at the head of the pixel block, the encoding target pixel data, that is, the original pixel data is used as it is as the predicted value, and the original pixel data is output as the encoded data. Therefore, the encoded data can be decoded with respect to the original pixel data included as the encoded data for each pixel block.

  As described with reference to FIG. 2, the encoding block including the encoded data encoded by the encoding unit 11A is packed into a packet in a predetermined format in the output processing unit 12, and the encoding device 1 Is output from.

(First example of known decoding process)
Next, a decoding process for decoding encoded data encoded by the above-described encoding unit 11A using a one-dimensional prediction process will be described. FIG. 6 shows an example of a configuration of a decoding unit 21A that performs a decoding process on encoded data encoded using a one-dimensional prediction process. The decoding unit 21A includes an output selector 202, a prediction error expansion unit 200, an adder 201, and a storage unit 203, and decodes encoded data by performing a process substantially opposite to that of the encoding unit 11A described above.

  The encoded data input to the decoding unit 21 </ b> A is input to the selection input terminal 202 </ b> A of the output selector 202 and is supplied to the prediction error expansion unit 200. Here, the encoded data includes original pixel data at the beginning of each packet and compressed prediction error values other than the beginning of the packet. The prediction error expansion unit 200 expands the compressed prediction error value of the input encoded data based on an inverse quantization table (not shown) corresponding to the quantization table used by the encoding unit 11A. Restore the prediction error value. The restoration prediction error value is input to one input terminal of the adder 201. The output of the storage unit 203 is input to the other input terminal of the adder 201. The adder 201 adds the restored prediction error value input to one input terminal and the output of the storage unit 203 input to the other input terminal to obtain decoded data.

  The decoded data output from the adder 201 is input to the selection input terminal 202B of the output selector 202. The output selector 202 selects one of the selection input terminals 202A and 202B according to the state of the signal first_word. The output selector 202 selects the selection input terminal 202B when the signal first_word is in the low state, and outputs the output of the adder 201 as decoded data. On the other hand, the output selector 202 selects the selection input terminal 202A when the signal first_word is in the high state, and outputs the input encoded data from the decoding unit 21A as decoded data. In this case, original pixel data is output as decoded data.

  The decoded data output from the output selector 202 is supplied to the output processing unit 22 shown in FIG. 4 as the decoded output of the decoding unit 21A and also to the storage unit 203. The storage unit 203 outputs the supplied data with a delay of, for example, one clock with respect to the input. The decoded data output from the storage unit 203 is input to the other input terminal of the adder 201 as described above.

  The output processing unit 22 shapes the decoded data supplied from the output selector 202 into a predetermined format and outputs it as output data from the decoding device 2.

(Second example of known encoding process)
Next, a second example of the encoding process that is a premise of the encoding unit 11 according to the present embodiment will be described. In the second example, the prediction value for the encoding target pixel is obtained in two dimensions using the pixel of the line including the encoding target pixel and the pixel of the previous line in the encoding order with respect to the line. In this example, encoding is performed.

  First, the two-dimensional prediction process will be schematically described. In the two-dimensional prediction process, with respect to the encoding target pixel, the previous pixel in the encoding order in the line including the encoding target pixel and the encoding order 1 for the line including the encoding target pixel. A prediction error is obtained by performing prediction of the encoding target pixel using pixels near the encoding target pixel in the previous line.

  The two-dimensional prediction process will be described more specifically with reference to FIG. Consider the encoding target pixel X on the nth line. For the encoding target pixel X on the n-th line, the pixel A is the previous pixel in the encoding order with respect to the encoding target pixel X on the n-th line. In other words, the pixel A is a pixel adjacent to the left of the encoding target pixel X. In addition, the pixels B, C, and D are respectively close to the encoding target pixel X immediately above, upper left, and upper right in the (n−1) th line immediately before the nth line in the encoding order. Pixel.

  In the following example, the predicted value x of the encoding target pixel X is obtained using the decoded values a to d of the pixels A to D. Here, a value that minimizes the difference from the value of the encoding target pixel X (encoding target pixel data) is selected from among the decoded values a to d of the adjacent pixels A to D of the encoding target pixel X.

  As another method, there is a method in which the decoding direction (prediction direction) is not transmitted to the decoding circuit, and the prediction direction is determined at the pixel position adjacent to or immediately above the encoding target pixel X. In this case, by using the decoded values a to d of the neighboring pixels A to D of the encoding target pixel X and the prediction direction that has already been obtained, the prediction error for the encoding target pixel X is expressed as the value of the encoding target pixel X. Can be obtained with an accuracy close to the prediction direction in the case of

  FIG. 8 shows a configuration of an example of a known encoding unit 11B for performing an encoding process using the two-dimensional prediction process described with reference to FIG. In FIG. 8, the same reference numerals are given to portions common to FIG. 5, and detailed description will be omitted as appropriate. The encoding unit 11B includes a subtracter 100, a prediction error compression unit 101, an output selector 102, and a prediction unit 120. In addition, the prediction unit 120 includes a prediction error expansion unit 110, an adder 111, a prediction value selector 112, a storage unit 130, a prediction mode selection unit 131, a prediction mode index storage unit 132, and a prediction pixel selection unit 133. And have.

  When performing two-dimensional prediction processing, the input processing unit 10 outputs the pixel data to be encoded and the signal first_word described above, and also outputs the signal line_first indicating the head of the line. The signal line_first is, for example, a signal that is in a high state during the period of the first pixel of the line and is in a low state during other periods.

  The encoding target pixel data output from the input processing unit 10 is sequentially input to the encoding unit 11B as input data, for example, according to a clock, and the subtracted input terminal of the subtracter 100 and the selection input terminal 102A of the output selector 102 are input. And the selection input terminal 112A of the prediction value selector 112, respectively.

  A prediction value output in units of pixels from the prediction unit 120 is input to the subtraction input terminal of the subtracter 100. The subtracter 100 subtracts the prediction value from the encoding target pixel data and outputs a prediction error value. The prediction error value is supplied to the prediction error compression unit 101. The prediction error compression unit 101 quantizes the prediction error value according to, for example, a predetermined quantization table to reduce the data amount and compress it. The compressed prediction error value obtained by compressing the prediction error value is supplied to the prediction error expansion unit 110 and also input to the selection input terminal 102B of the output selector 102.

  The output selector 102 (first selection unit) selects one of the selection input terminals 102A and 102B according to the value of the signal first_word supplied from the input processing unit 10, and is input to the selected input terminal Data is output from the encoding unit 11B as encoded data. For example, the output selector 102 selects the selection input terminal 102A when the signal first_word is in a high state, and outputs the encoding target pixel data, that is, the original pixel data as it is as the encoded data. On the other hand, the output selector 102 selects the selection input terminal 102B when the signal first_word is in a low state, for example, and outputs the compressed prediction error value output from the prediction error compression unit 101 as encoded data.

  The prediction error decompression unit 110 decompresses the compressed prediction error value according to the inverse quantization table corresponding to the quantization table used in the prediction error compression unit 101, and outputs a restored prediction error value obtained by restoring the prediction error value before compression. To do. The restoration prediction error value is input to one input terminal of the adder 111. The adder 111 adds a decompression prediction error value input to one input terminal and a prediction value output from the prediction pixel selection unit 133 described later, and a compressed prediction error output from the prediction error compression unit 101. Outputs the decoded value obtained by decoding the value. The decoded value output from the adder 111 is input to the selection input terminal 112B of the predicted value selector 112.

  The prediction value selector 112 (second selection unit) selects one of the selection input terminals 112A and 112B according to the value of the signal first_word, and outputs the data input to the selected input terminal as a decoded value To do. For example, if the signal first_word is in a high state, the prediction value selector 112 selects the selection input terminal 112A and outputs the encoding target pixel data as a decoded value. On the other hand, the prediction value selector 112 selects the selection input terminal 112B when the signal first_word is in the low state, and outputs the decoded value output from the adder 111. The decoded value output from the predicted value selector 112 is stored in the storage unit 130.

  In the encoding unit 11B that performs two-dimensional encoding, the storage unit 130 stores a plurality of decoded values. More specifically, the storage unit 130 stores the decoded value for the encoding target pixel data, and is adjacent to the left side of the encoding target pixel X described above with reference to FIG. The decoded value for each of the pixels A to D is stored. As an example, the storage unit 130 uses a line memory capable of storing one line and a flip-flop for storing the immediately preceding decoded value, the decoded value for the acquired line including the encoding target pixel data, It is conceivable to store a decoded value corresponding to each pixel of the previous line in the coding order with respect to the line.

  The prediction mode selection unit 131 selects a prediction mode using the decoded value x and the decoded values a to d stored in the storage unit 130. Specifically, the prediction mode selection unit 131 obtains the difference between the decoded value x and each decoded value a to d, and the direction corresponding to the decoded value having the smallest difference among the decoded values a to d (prediction Direction) as the prediction mode. The direction corresponding to the decoded value means the direction of the pixel corresponding to the decoded value with respect to the encoding target pixel X. For example, when the difference between the decoded value a and the decoded value x is the smallest among the decoded values a to d, the decoded value a is the value of the pixel A adjacent to the left of the encoding target pixel X as shown in FIG. Therefore, the prediction mode is “left”. This prediction mode is a prediction mode for the encoding target pixel that is next input to the encoding unit 11B in the encoding order of the encoding target pixel X.

  The prediction mode selection unit 131 outputs a prediction mode index indicating the prediction mode. The prediction mode index is stored in the prediction mode index storage unit 132. The prediction pixel selection unit 133 selects and reads out the decoded value stored in the storage unit 130 according to the prediction mode index stored in the prediction mode index storage unit 132. The prediction pixel selection unit 133 outputs the decoded value read from the storage unit 130 as a prediction value for predicting the pixel value when the encoding target pixel data is compressed and expanded, and inputs the prediction value to the subtraction input terminal of the subtracter 100. At the same time, the signal is input to the other input terminal of the adder 111.

  That is, the prediction pixel selection unit 133 obtains the decoded value corresponding to the prediction mode indicated by the prediction mode index obtained using the previous encoding target pixel in the encoding order of the current encoding target pixel X, The prediction value of the encoding target pixel X is selected.

  Although not shown, since there is no decoded pixel in the upper line in the first line, a process for forcibly setting the prediction mode to “left” is performed. Therefore, it is also necessary to input a signal indicating the first line to the encoding unit 11B. At this time, since it is necessary to inform the decoding side that the decoded value of the pixel adjacent to the left side is forcibly used as the predicted value in the generated packet, for example, a process of setting the control signal (region F) to high is performed. In the first embodiment to be described later, it is proposed to use a control signal (region F) as a signal indicating LBL. However, in the sense of using the decoded value of the pixel on the left side in decoding, This is the same as the control signal (area F) for indicating the first line.

  The encoded data output from the output selector 102 of the encoding unit 11B is supplied to the output processing unit 12, packed into a packet as described with reference to FIG. 2, and output from the encoding device 1.

  FIG. 9 shows an example of a signal output from the encoding device 1. FIG. 9A shows a clock. For example, one pixel data is input to the encoding unit 11B for each clock. FIG. 9B and FIG. 9C show examples of the signal line_first and the signal first_word, respectively. FIG. 9D shows an example of a packet output from the output processing unit 12. At the beginning of each line, the signal line_first is set to the high state. Also, the signal first_word is set to the high state at the head of each packet # 1, # 2,.

(Second example of known decoding process)
Next, a decoding process for decoding encoded data encoded using the two-dimensional prediction process in the encoding unit 11B described above will be described. FIG. 10 shows a configuration of an example of a known decoding unit 21B that performs a decoding process on encoded data encoded using a two-dimensional prediction process. In FIG. 10, the same reference numerals are given to portions common to the decoding unit 21 </ b> A shown in FIG. 6 described above, and detailed description thereof is omitted. The decoding unit 21B includes a prediction error expansion unit 200, an adder 201, an output selector 202, a storage unit 210, a prediction mode selection unit 211, a prediction mode index storage unit 212, and a prediction pixel selection unit 213. .

  The encoded data input to the decoding unit 21 </ b> B is input to the selection input terminal 202 </ b> A of the output selector 202 and also supplied to the prediction error extending unit 200. Here, the encoded data includes original pixel data at the beginning of each packet and compressed prediction error values other than the beginning of the packet. The prediction error expansion unit 200 dequantizes the compressed prediction error value of the input encoded data based on an inverse quantization table (not shown) corresponding to the quantization table used by the encoding unit 11B described above. Decompress and restore the prediction error value. The restoration prediction error value is input to one input terminal of the adder 201. The other input terminal of the adder 201 receives decoded data as a prediction value output from a prediction pixel selection unit 213 described later. The adder 201 adds the restored prediction error value input to one input terminal and the decoded data as the predicted value input to the other input terminal, and obtains decoded data to be output as a decoded output.

  The decoded data output from the adder 201 is input to the selection input terminal 202B of the output selector 202. The output selector 202 selects one of the selection input terminals 202A and 202B according to the state of the signal first_word. The output selector 202 selects the selection input terminal 202B when the signal first_word is in the low state, and outputs the output of the adder 201 as decoded data. On the other hand, the output selector 202 selects the selection input terminal 202A when the signal first_word is in the high state, and outputs the input encoded data from the decoding unit 21B as decoded data. In this case, original pixel data is output as decoded data.

  The decoded data output from the output selector 202 is also supplied to the storage unit 210. In the decoding unit 21B, the storage unit 210, the prediction mode selection unit 211, the prediction mode index storage unit 212, and the prediction pixel selection unit 213 are respectively the storage unit 130, the prediction mode selection unit 131, and the prediction mode index in the encoding unit 11B described above. This corresponds to the storage unit 132 and the predicted pixel selection unit 133.

  The storage unit 210, the prediction mode selection unit 211, the prediction mode index storage unit 212, and the prediction pixel selection unit 213, similarly to the encoding unit 11B, decode data to be input to the other input terminal of the adder 201. Using the decoded data stored in the storage unit 210, a line including the decoded data output from the output selector 202 immediately before and a line preceding the line in decoding order are obtained.

  The storage unit 210 stores a plurality of decoded data. More specifically, the storage unit 210 uses, for example, a line memory capable of storing one line, stores the decoded data output from the output selector 202 immediately before, and is similar to the method described with reference to FIG. In addition, the decoded data for the pixels A to D adjacent to the left side, the upper left side, the upper right side, and the upper right side of the decoded data are stored. Hereinafter, the decoded data output from the output selector 202 immediately before is referred to as decoded data x ′, and the decoded data for each of the pixels A to D is referred to as decoded data a ′, b ′, c ′, and d ′.

  The prediction mode selection unit 211 selects a prediction mode using the decoded data x ′ and the decoded data a ′ to d ′ stored in the storage unit 210. Specifically, the prediction mode selection unit 211 obtains the difference between the decoded data x ′ and each decoded data a ′ to d ′, and sets the decoded data having the smallest difference among the decoded data a ′ to d ′. Select the corresponding direction as the prediction mode.

  The prediction mode selection unit 211 outputs a prediction mode index indicating the prediction mode. The prediction mode index is stored in the prediction mode index storage unit 212. The prediction pixel selection unit 213 selects and reads the decoded data stored in the storage unit 210 according to the prediction mode index stored in the prediction mode index storage unit 212. That is, the prediction pixel selection unit 213 selects decoded data corresponding to the prediction mode indicated by the prediction mode index obtained using the previous decoded data in the encoding order of the decoded data x ′. The prediction pixel selection unit 213 outputs the selected decoded data. The decoded data output from the prediction pixel selection unit 213 is input to the other input terminal of the adder 201.

(Encoding process according to the first embodiment)
According to the known encoding technique in which the above-described two-dimensional prediction is performed and the encoding process is performed, local decoding has already been performed on the line including the pixel to be encoded and the previous line in the encoding order of the line. In addition, the prediction value of the encoding target pixel is obtained using the decoded values of a plurality of pixels in the vicinity of the encoding target pixel. Therefore, the prediction accuracy is increased and the encoding efficiency is improved as compared with the case of performing the encoding process based on the one-dimensional prediction described with reference to FIG.

  On the other hand, when encoding processing using two-dimensional prediction by a known technique is applied to image data in which two different images are inserted every other line as in the LBL method, for example, the prediction direction is actually May be different from the prediction direction in which the prediction error is minimized at the encoding target pixel position. In this case, the prediction error in the vertical direction becomes large, and the prediction error may propagate downward.

  Therefore, in the encoding process according to the first embodiment, the prediction mode is switched in accordance with the control signal indicating the LBL method, so that the image data of the LBL method and general image data composed of one image on the entire surface are supported. To do.

  FIG. 11 shows an exemplary configuration of the encoding unit 11 according to the first embodiment. In FIG. 11, parts common to the encoding unit 11 </ b> B illustrated in FIG. 8 described in the second example of the known encoding process are denoted by the same reference numerals, and detailed description thereof is omitted. 11 is in the middle of a path for supplying a prediction mode index from the prediction mode selection unit 131 to the prediction mode index storage unit 132 in the prediction unit 120 ′ with respect to the encoding unit 11B in FIG. In addition, the prediction mode selector 150 is additionally inserted.

  The prediction mode selector 150 switches between the selection input terminal 150A and the selection input terminal 150B in accordance with a predetermined control signal. For example, the prediction mode selector 150 selects the selection input terminal 150A when the control signal is low, and selects the selection input terminal 150B when the control signal is high. The prediction mode index output from the prediction mode selection unit 131 is input to the selection input terminal 150A. On the other hand, a prediction mode index indicating “left” is input to the selection input terminal 150B.

  When the control signal is in a low state, the operation of the encoding unit 11 is the same as that of the encoding unit 11B described with reference to FIG. That is, among the decoded values a to d of the neighboring pixels A to D of the encoding target pixel X, a value that minimizes the difference from the encoding target pixel value X is selected as the predicted value x and encoded. I do.

  A method of determining the prediction direction at the pixel position adjacent to or immediately above the encoding target pixel X without transmitting to the decoding side which decoding value (prediction direction) described above is selected may be used. .

  On the other hand, when the control signal is in the high state, the prediction mode index indicating “left” is forcibly supplied to the prediction mode index storage unit 132. In this case, the prediction pixel selection unit 133 is forced to select the decoded value a corresponding to the pixel A adjacent to the left of the encoding target pixel X stored in the storage unit 130. That is, while the control signal is in the high state, the decoded value a is sequentially input as a predicted value to the subtraction input terminal of the subtracter 100. This is the same as the operation of the encoding unit 11A that performs encoding based on the one-dimensional prediction described with reference to FIG.

  Thus, the subtraction of the subtraction unit 100 based on each prediction value stored in the storage unit by the prediction mode selection unit 131, the prediction mode index storage unit 132, the prediction pixel selection unit 133, and the prediction mode selector 150. A predicted value output unit for obtaining a predicted value to be input to the input terminal is configured.

  Therefore, when the image data input to the encoding unit 11 is image data according to the LBL method, the control signal is set to a high state, and when the input image data is general image data, the control signal is set to a low state. . Thus, when LBL image data is input, encoding based on one-dimensional prediction is performed, and when general image data is input, encoding based on two-dimensional prediction is performed. This can be realized with a common configuration.

  A control signal indicating the LBL method is transmitted to the encoding device 1 from a supply source that supplies image data to the encoding device 1, for example.

  In the above description, a plurality of pixels in the vicinity of the encoding target pixel X (in this example, as pixels in the previous line in the encoding order of the line including the encoding target pixel X with respect to the encoding target pixel X). The prediction is performed using 3 pixels), but this is not limited to this example. For example, prediction may be performed using one pixel in the vicinity of the encoding target pixel X as a pixel in the previous line in the encoding order of the line including the encoding target pixel X. In this case, for example, it is conceivable to use a pixel immediately above the encoding target pixel X.

(Decoding process according to the first embodiment)
FIG. 12 shows an exemplary configuration of the decoding unit 21 according to the first embodiment. In FIG. 12, parts common to the decoding unit 21B shown in FIG. 10 described in the second example of the known decoding process are denoted by the same reference numerals, and detailed description thereof is omitted. The decoding unit 21 illustrated in FIG. 12 has a prediction mode selector 220 in the middle of a path for supplying a prediction mode index from the prediction mode selection unit 211 to the prediction mode index storage unit 212 with respect to the decoding unit 21B of FIG. It is different in that it is additionally inserted.

  The operation of the prediction mode selector 220 is the same as the operation of the prediction mode selector 150 in the encoding unit 11 shown in FIG. That is, the prediction mode selector 220 selects the selection input terminal 220A when the control signal indicating the LBL method is low, and selects the selection input terminal 220B when the control signal is high. The prediction mode index output from the prediction mode selection unit 211 is input to the selection input terminal 220A. On the other hand, a prediction mode index indicating “left” is input to the selection input terminal 220B.

  When the control signal is in a low state, the operation of the decoding unit 21 is the same as that of the decoding unit 21B described with reference to FIG. That is, the decoding unit 21 applies the decoded data x ′ output from the output selector 202 immediately before and the pixels A to D adjacent to the left side, the upper left side, the upper right side, and the upper right side of the pixel corresponding to the decoded data x ′. Using the decoded data a ′ to d ′, a predicted value for the decoded data to be decoded next in the decoding order is obtained.

  On the other hand, when the control signal is in a high state, the prediction mode index indicating “left” is forcibly supplied to the prediction mode index storage unit 212, and the prediction pixel selection unit 213 is stored in the storage unit 210. The decoded data a ′ for the pixel to the left of the pixel corresponding to the decoded data decoded immediately before is forcibly selected. That is, while the control signal is in the high state, the decoded data a ′ is sequentially input to the other input terminal of the adder 201. This is the same as the operation of the decoding unit 21A that performs encoding based on the one-dimensional prediction described with reference to FIG.

  Therefore, when encoded data encoded corresponding to the LBL method is input to the decoding unit 21, the control signal is set to a high state, and encoded data encoded corresponding to general image data is input. If so, the control signal is set to a low state. Accordingly, when encoded data obtained by encoding LBL image data is input, decoding based on one-dimensional prediction is performed, and when encoded data obtained by encoding general image data is input. A process of performing decoding based on two-dimensional prediction can be realized with a common configuration.

  As described above, the prediction mode selection unit 211, the prediction mode index storage unit 212, the prediction pixel selection unit 213, and the prediction mode selector 220 constitute a prediction value output unit that obtains a decoded prediction value to be added to the addition unit. The

  For example, in the encoding device 1, the control signal indicating the LBL method corresponds to the LBL method in which the encoded data stored in the packet corresponds to the 1-bit region F of the MSB in the packet configuration illustrated in FIG. It is conceivable to store a flag indicating whether or not the encoded data is encoded. When the packet is input, the decoding device 2 detects one bit of the MSB of the packet in the input processing unit 20 and generates a control signal indicating whether or not the LBL method is used.

  Not only this but the control signal which shows whether it is LBL system may be transmitted with respect to the decoding apparatus 2 from the supply source which supplies a packet with respect to the decoding apparatus 2. FIG.

(Second Embodiment)
Next, a second embodiment will be described. The second embodiment is an example in which the encoding device 1 including the encoding unit 11 and the decoding device 2 according to the first embodiment described above are applied to an image processing device having an image processing unit. FIG. 13 shows an exemplary configuration of an image processing apparatus 300 according to the second embodiment. Here, as an example of the image processing apparatus 300, a video apparatus that inputs image data based on a high-definition image and supplies the image data to a display is applied. In FIG. 13, the same reference numerals are given to the portions common to FIGS. 1 and 4 described above, and detailed description thereof is omitted.

  The image processing apparatus 300 includes an input unit 310, an image processing unit 311, and a display 312. The input unit 310 receives image data. The input unit 310 accepts input of image data as a high-definition image. The input source of the high-definition image is not particularly limited, but various sources such as a tuner that receives digital television broadcasts, a player that reproduces a disc recording medium such as a Blu-ray (registered trademark) disc, and a computer device are conceivable. The input unit 310 supplies the input image data to the image processing unit 311. In addition, it is determined whether or not the input image data is image data based on the LBL method. When the input image data is identified as image data based on the LBL method, a signal indicating that the image data is based on the LBL method is displayed together with the image data. This is supplied to the processing unit 311.

  The image processing unit 311 performs predetermined image processing on the supplied image data using the memory 321. The type of image processing performed by the image processing unit 311 is not particularly limited. Various types of processing such as enhancement processing, frame rate conversion processing, color tone adjustment processing, and resolution conversion processing are conceivable.

  The image processing unit 311 can perform the above-described image processing using the memory 321. As an example, the image processing unit 311 temporarily stores the image data supplied from the input unit 310 in the memory 321 via the memory interface (I / F) 320. Then, image processing is performed on the image data, for example, in units of pixels while reading the image data from the memory via the memory I / F 320. The image data subjected to the image processing is sequentially written from the image processing unit 311 to the memory 321 via the memory I / F 320.

  The image data processed by the image processing unit 311 is supplied to the display 312. For example, the image processing unit 311 writes the image data for which image processing has been completed to the memory 321 via the memory I / F 320. When the image processing for one frame is completed, the image processing unit 311 reads image data from the memory 321 via the memory I / F 320 and supplies the image data to the display 312. The display 312 displays an image based on the supplied image data.

  In such a configuration of the image processing apparatus 300, the encoding apparatus 1 including the encoding unit 11 and the decoding apparatus 2 according to the first embodiment are applied to the memory I / F 320. More specifically, as illustrated in FIG. 13, the memory I / F 320 configures the input processing unit 10, the encoding unit 11, the output processing unit 12, and the decoding device 2 that configure the encoding device 1. An input processing unit 20, a decoding unit 21, and an output processing unit 22 are included.

  For example, image data output sequentially from the image processing unit 311 in units of lines is supplied to the memory I / F 320 and input to the input processing unit 10. At the same time, a control signal indicating whether or not the output image data is image data based on the LBL method is supplied from the image processing unit 311 to the memory I / F 320 and input to the encoding unit 11. The input processing unit 10 divides input image data for each predetermined number of pixels to form a pixel block. At the same time, the input processing unit 10 outputs the signal line_first and the signal first_word in a high state or a low state, respectively, according to the position of the pixel block and the pixel data in the pixel block. The input processing unit 10 can acquire information indicating the head of the line from the image processing unit 311, for example.

  The pixel block output from the input processing unit 10 and the signal first_word are input to the encoding unit 11. As described with reference to FIG. 11, the encoding unit 11 encodes the pixel data of the pixel block to generate an encoded block.

  At this time, if the control signal supplied from the image processing unit 311 indicates that the image data output from the image processing unit 311 is image data based on the LBL method, the selection input terminal 150B in the prediction mode selector 150 is When selected, the encoding unit 11 performs an encoding process based on one-dimensional prediction. On the other hand, when the control signal indicates that the image data output from the image processing unit 311 is not image data by the LBL method but general image data, the selection input terminal 150A is selected by the prediction mode selector 150. Then, the encoding unit 11 performs an encoding process based on two-dimensional prediction.

  The encoded data output from the encoding unit 11 is packed into a packet having a predetermined size by the output processing unit 12 and output from the memory I / F 320. At this time, identification information indicating whether or not the encoded data stored in the packet corresponds to the LBL method is stored in the 1-bit region F of the MSB of the packet. The encoded block packet output from the memory I / F 320 is written in the memory 321.

  The image processing unit 311 instructs the memory I / F 320 to read the image data (encoded block) stored in the memory 321. In accordance with this instruction, the memory I / F 320 reads the encoded block from the memory 321 for each packet and inputs it to the input processing unit 20. At this time, the input processing unit 20 can acquire information indicating the head of the line or the head of each encoded block from the image processing unit 311, for example. Information indicating the head of each encoded block may be generated by the input processing unit 20 itself.

  The input processing unit 20 extracts the encoded data from the input encoded block and sequentially supplies the encoded data to the decoding unit 21, and also sets the signal first_word to a high state or low level according to the position of the encoded data in the encoded block. Output in a state. Further, the input processing unit 20 determines whether the encoded data stored in the encoded block is encoded data encoded according to the LBL scheme based on the identification information stored in the MSB area F of the encoded block. Is generated and supplied to the decoding unit 21.

  The decoding unit 21 selects the input encoded data according to the state of the signal first_word, outputs the encoded data stored at the head of the encoded block as decoded data, and outputs the other encoded data as it is. After the inverse quantization, decoded data is generated by adding the previous encoded data in the decoding order.

  At this time, when the control signal supplied from the input processing unit 20 indicates encoded data by the LBL method, the selection input terminal 220B is selected by the prediction mode selector 220, and the decoding unit 21 is one-dimensional. The decoding process based on the prediction is performed. On the other hand, when the control signal indicates that the encoded data is not the image data by the LBL method but the encoded data by encoding the general image data, the selection input terminal 220A is selected by the prediction mode selector 220. Then, the decoding unit 21 performs a decoding process based on the two-dimensional prediction.

  The decoded data output from the decoding unit 21 is shaped into a predetermined format by the output processing unit 22 and supplied from the memory I / F 320 to the image processing unit 311.

  As described above, the encoding unit 11 and the decoding unit 21 according to the first embodiment are used by being incorporated in the memory I / F 320 of the memory 321 accessed by the image processing unit 311, so that the image data stored in the memory 321 can be stored. The size can be compressed. In addition, since encoding is performed on a pixel basis, high-speed processing is possible. Further, the memory I / F 320 can switch between the one-dimensional prediction and the two-dimensional prediction based on the control signal. For this reason, both the image data based on the LBL system and the general image data not based on the LBL system can be handled with a common configuration.

DESCRIPTION OF SYMBOLS 1 Encoding apparatus 2 Decoding apparatus 10,20 Input processing part 11,11A, 11B Encoding part 12,22 Output processing part 21,21A, 21B Decoding part 100 Subtractor 101 Prediction error compression part 102,202 Output selector 103 Prediction part 110, 200 Prediction error expansion unit 111, 201 Adder 113, 130, 210 Storage unit 131, 211 Prediction mode selection unit 132, 212 Prediction mode index storage unit 133, 213 Prediction pixel selection unit 150, 220 Prediction mode selector

Claims (8)

A prediction error acquisition unit that acquires a prediction error that is an error between the pixel value of the input pixel and the first prediction value obtained by predicting the pixel value;
A compression unit for compressing the prediction error;
A decompression unit for decompressing the prediction error compressed by the compression unit;
An addition unit that adds the prediction error expanded by the expansion unit and the first prediction value to generate a second prediction value;
At least a second predicted value, a third predicted value corresponding to a pixel adjacent to the input pixel in a line preceding the line including the input pixel in coding order, and the input A storage unit that stores a fourth predicted value corresponding to a pixel preceding by one in encoding order with respect to the pixel;
A prediction value output unit that outputs the first prediction value obtained based on at least two prediction values of the second prediction value, the third prediction value, and the fourth prediction value; And
The predicted value output unit
When the predetermined control signal is received, the first predicted value is obtained based on the second predicted value and the fourth predicted value, and when the control signal is not received, the second predicted value is obtained. An encoding apparatus, wherein the first prediction value is obtained based on a prediction value, the third prediction value, and the fourth prediction value. The storage unit
Storing a plurality of third prediction values respectively corresponding to a plurality of pixels adjacent to the input pixel in a line preceding by a coding order with respect to a line including the input pixel;
The predicted value output unit
The first predicted value is obtained based on the second predicted value, the plurality of third predicted values, and the fourth predicted value when the control signal is not received. Item 4. The encoding device according to Item 1. A first selection unit that selects one of the input pixel and the output of the compression unit and outputs it as an encoded output;
A second selection unit that selects one of the input pixel and the output of the addition unit and stores the second prediction value as the second predicted value in the storage unit;
The first selection unit and the second selection unit are:
The encoding apparatus according to claim 1 or 2, wherein the input pixel is selected at the head of each block obtained by dividing the line into a predetermined number of pixels. A prediction error acquisition step of acquiring a prediction error that is an error between the pixel value of the input pixel and the first prediction value obtained by predicting the pixel value;
A compression step of compressing the prediction error;
An expansion step of expanding the prediction error compressed by the compression step;
An addition step of adding the prediction error expanded by the expansion step and the first prediction value to generate a second prediction value;
At least a second predicted value, a third predicted value corresponding to a pixel adjacent to the input pixel in a line preceding the line including the input pixel in coding order, and the input A storage step of storing, in the storage unit, a fourth predicted value corresponding to the pixel immediately preceding the pixel in the encoding order;
A predicted value output step of outputting the first predicted value obtained based on at least two predicted values of the second predicted value, the third predicted value, and the fourth predicted value; And
The predicted value output step includes:
When the predetermined control signal is received, the first predicted value is obtained based on the second predicted value and the fourth predicted value, and when the control signal is not received, the second predicted value is obtained. An encoding method, wherein the first predicted value is obtained based on a predicted value, the third predicted value, and the fourth predicted value. An output obtained by compressing and encoding a prediction error that is an error between a pixel value of an input pixel and a first prediction value obtained by predicting the pixel value is expanded, and the expanded prediction error and the first prediction value are obtained. The second predicted value is added to generate a second predicted value, and when the predetermined control signal is not received, the second predicted value and the line previous to the line including the input pixel in the coding order, Based on a third prediction value corresponding to a pixel close to the input pixel and a fourth prediction value corresponding to the pixel immediately before in the coding order with respect to the input pixel, the first prediction value is calculated. When the predetermined control signal is received, the first prediction value is obtained based on the second prediction value and the fourth prediction value, and the prediction error is compressed and encoded. A decoding device that performs a decoding process on the device,
A decompression unit for decompressing the compression prediction error;
An addition unit that adds a decoded prediction value to the compressed prediction error expanded by the expansion unit and outputs the result as a first decoded pixel;
The first decoded pixel; a second decoded pixel adjacent to the first decoded pixel in a line preceding the line including the first decoded pixel in decoding order; and the first A predicted value output unit that outputs the decoded predicted value obtained based on at least two decoded pixels of the first decoded pixel in decoding order with respect to the decoded pixels of
The predicted value output unit
When a predetermined control signal is received, the decoded prediction value is obtained based on the first decoded pixel and the third decoded pixel, and when the control signal is not received, the first decoded pixel And the decoding prediction value based on the second decoding pixel and the third decoding pixel. The storage unit
Storing a plurality of the second decoded pixels adjacent to the first decoded pixel in the line preceding by one in decoding order with respect to the line including the first decoded pixel;
The predicted value output unit
6. The decoded prediction value is obtained based on the first decoded pixel, the plurality of second decoded pixels, and the third decoded pixel when the control signal is not received. The decoding device according to 1. A selection unit that selects one of the compressed prediction error and the first decoded pixel and outputs it as a decoded output;
The decoding device according to claim 5 or 6, wherein the selection unit selects the compression prediction error at a position corresponding to a head of each block obtained by dividing a line into a predetermined number of pixels. An output obtained by compressing and encoding a prediction error that is an error between a pixel value of an input pixel and a first prediction value obtained by predicting the pixel value is expanded, and the expanded prediction error and the first prediction value are obtained. The second predicted value is added to generate a second predicted value, and when the predetermined control signal is not received, the second predicted value and the line previous to the line including the input pixel in the coding order, Based on a third prediction value corresponding to a pixel close to the input pixel and a fourth prediction value corresponding to the pixel immediately before in the coding order with respect to the input pixel, the first prediction value is calculated. When the predetermined control signal is received, the first prediction value is obtained based on the second prediction value and the fourth prediction value, and the prediction error is compressed and encoded. A decoding method for performing a decoding process on
An expansion step of expanding the compression prediction error;
An addition step of adding a decoded prediction value to the compressed prediction error expanded by the expansion step and outputting as a first decoded pixel;
The first decoded pixel; a second decoded pixel adjacent to the first decoded pixel in a line preceding the line including the first decoded pixel in decoding order; and the first A predicted value output step of outputting the decoded predicted value obtained based on at least two decoded pixels of the first decoded pixel in decoding order with respect to the decoded pixels of
The predicted value output step includes:
When a predetermined control signal is received, the decoded prediction value is obtained based on the first decoded pixel and the third decoded pixel, and when the control signal is not received, the first decoded pixel And the decoding prediction value is obtained based on the second decoding pixel and the third decoding pixel.

Images