Apparatus and method for encoding and decoding moving picture using adaptive scanning
Provided is an apparatus and method for encoding/decoding moving pictures based on adaptive scanning. The moving picture apparatus and method can increase a compression rate based on adaptive scanning by performing intra prediction onto blocks of a predetermined size, and scanning coefficients acquired from Discrete Cosine Transform (DCT) of a residue signal and quantization differently according to the intra prediction mode. The moving picture encoding apparatus includes: a mode selector for selecting and outputting a prediction mode; a predictor for predicting pixel values of pixels to be encoded of an input video based on the prediction mode to thereby output a residue signal block; a transform/quantization unit for performing DCT onto the residue signal block and quantizing the transformed residue signal block; and an encoder for adaptively scanning and encoding the quantized residue signal block based on the prediction mode.
1. An apparatus for encoding images using adaptive scanning, the apparatus comprising:
a mode selector configured to select an intra prediction mode when intra prediction is applied, and output the selected intra prediction mode;
an intra predictor configured to predict pixel values of pixels of an input image to be encoded using the selected intra prediction mode, and output a residue signal block based on the predicted pixel values;
a transform/quantization unit configured to transform the residue signal block, quantize the transformed residue signal block, and output the transformed and quantized residue signal block; and
an encoder configured to adaptively scan and encode the transformed and quantized residue signal block based on the selected intra prediction, mode;
wherein the encoder is further configured to perform a horizontal scan when the selected intra prediction mode is a vertical mode, and perform a vertical scan when the selected intra prediction mode is a horizontal mode.
2. The apparatus as recited in claim 1 , wherein the encoder is further configured to scan all coefficients in a first row of the transformed and quantized residue signal block before scanning any coefficient in any other row of the transformed and quantized residue signal block when the encoder performs the horizontal scan.
3. The apparatus as recited in claim 1 , wherein the encoder is further configured to scan all coefficients in a first column of the transformed and quantized residue signal block before scanning any coefficient in any other column of the transformed and quantized residue signal block when the encoder performs the vertical scan.
4. The apparatus as recited in claim 1 , wherein the encoder is further configured to perform entropy encoding of coefficients of the transformed and quantized residue signal block acquired and arrayed by adaptively scanning the transformed and quantized residue signal block based on the selected intra prediction mode.
5. An apparatus for decoding images using adaptive scanning, the apparatus comprising:
a decoder configured to receive an encoded bitstream, decode the encoded bitstream to obtain a decoded signal, and output the decoded signal;
a scanning method detector configured to receive the decoded signals signal from the decoder, acquire information on a scanning method used in an encoding process by which the encoded bitstream was obtained and to be used to scan the decoded signal, and output the scanning method information and the decoded signal; and
a video reconstructing unit for configured to reconstruct an image from the decoded signal based on the scanning method information, and output the reconstructed image;
wherein the scanning method depends on an intra prediction mode used in the encoding process; and
the video reconstructing unit is further configured to perform a horizontal scan when reconstructing the image from the decoded signal when the intra prediction mode is a vertical mode, and perform a vertical scan when reconstructing the image from the decoded signal when the intra prediction mode is a horizontal mode.
6. The apparatus as recited in claim 5 , wherein the video reconstructing unit is further configured to scan all coefficients in a first row are of the decoded signal before scanning any coefficient in any other row of the decoded signal when the video reconstructing unit performs the horizontal scan.
7. The apparatus as recited in claim 5 , wherein the video reconstructing unit is further configured to scan coefficients in a first column of the decoded signal before scanning any coefficient in any other column of the decoded signal when the video reconstructing unit performs the vertical scan.
8. A method of encoding images using adaptive scanning, the method comprising:
selecting an intra prediction mode when intra prediction is applied;
predicting pixel values of pixels of an input image to be encoded using the selected intra prediction mode; and
outputting a residue signal block based on the predicted pixel values;
transforming the residue signal block;
quantizing the transformed residue signal block; and
adaptively scanning and encoding the transformed and quantized residue signal block based on the selected intra prediction mode;
wherein the adaptively scanning comprises:
performing a horizontal scan when the selected intra prediction mode is a vertical mode; and
performing a vertical scan when the selected intra prediction mode is a horizontal mode.
9. The encoding-method as recited in claim 8 , wherein the performing a horizontal scan comprises scanning all coefficients in a first row of the transformed and quantized residue signal block before scanning any coefficient in any other row of the transformed and quantized residue signal block when performing the horizontal scan.
10. The encoding-method as recited in claim 8 , wherein the performing a vertical scan comprises scanning all coefficients in a first column the transformed and quantized residue signal block before scanning any coefficient in any other column of the transformed and quantized residue signal block when performing the vertical scan.
11. A method of decoding images using adaptive scanning, the decoding method comprising:
decoding an encoded bitstream to obtain a decoded signal;
acquiring information on a scanning method used in an encoding process by which the encoded bitstream was obtained and to be used to scan the decoded signal; and
reconstructing an image from the decoded signal based on the scanning method information;
wherein the scanning method depends on an intra prediction mode used in the encoding process; and
the reconstructing comprises:
performing a horizontal scan when reconstructing the image from the decoded signal when the intra prediction mode is a vertical mode; and
performing a vertical scan when reconstructing the image from the decoded signal when the intra prediction mode is a horizontal mode.
12. The method as recited in claim 11 , wherein wherein the performing a horizontal scan comprises scanning all coefficients in a first row are of the decoded signal before scanning any coefficient in any other row of the decoded signal when performing the horizontal scan.
13. The apparatus as recited in claim 5 , wherein the decoder is further configured to perform entropy decoding of the encoded bitstream to obtain the decoded signal.
14. The method as recited in claim 8 , wherein the encoding comprises performing entropy encoding of coefficients of the transformed and quantized residue signal block acquired and arrayed by adaptively scanning the transformed and quantized residue signal block based on the selected intra prediction mode.
15. The method as recited in claim 11 , wherein the performing a vertical scan comprises scanning all coefficients in a first column of the decoded signal before scanning any coefficient in any other column of the decoded signal when performing the vertical scan.
16. The method as recited in claim 11 , wherein the decoding comprises performing entropy decoding of the encoded bitstream to obtain the decoded signal.