WO2006009400A1 - Method and apparatus to transform/inverse transform and quantize/dequantize color image, and method and apparatus to encode/decode color image using it - Google Patents

Method and apparatus to transform/inverse transform and quantize/dequantize color image, and method and apparatus to encode/decode color image using it Download PDF

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Publication number
WO2006009400A1
WO2006009400A1 PCT/KR2005/002354 KR2005002354W WO2006009400A1 WO 2006009400 A1 WO2006009400 A1 WO 2006009400A1 KR 2005002354 W KR2005002354 W KR 2005002354W WO 2006009400 A1 WO2006009400 A1 WO 2006009400A1
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residual
transform
colour
color image
flag
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PCT/KR2005/002354
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French (fr)
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Woo-Shik Kim
Hyun-Mun Kim
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Samsung Electronics Co., Ltd.
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Application filed by Samsung Electronics Co., Ltd. filed Critical Samsung Electronics Co., Ltd.
Publication of WO2006009400A1 publication Critical patent/WO2006009400A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/48—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • H04N19/122—Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/124—Quantisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
    • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/186—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a colour or a chrominance component
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/46—Embedding additional information in the video signal during the compression process
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/63—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets

Definitions

  • the present invention relates to encoding and decoding of a color image, and more particularly, to a method and an apparatus for transforming/inverse transforming and quantizing/dequantizing a residual transformed color image and a method and an apparatus for encoding/decoding the color image using the same .
  • a color image is color transformed and then encoded.
  • Types of color coordinate systems are various.
  • a standard coordinate system is an RGB coordinate system.
  • An RGB image is transformed into an YCbCr image, divided into luminance and chrominance components, and encoded.
  • YCoCg-R is developed by Microsoft Corporation.
  • the residue images of the chrominance components are formed through the temporal and spatial estimations during encoding and transformation is performed with respect to the residue of the chrominance components so as to remove the redundancy of the residue of the chrominance components. Disclosure of Invention
  • the present invention provides a method and an apparatus for quantizing and transforming a color image by which a residual transformation can be applied in any estimation mode to encode the color image.
  • the present invention also provides a method and an apparatus for encoding a color image using the method and the apparatus for quantizing and transforming the color image.
  • the present invention also provides a method and an apparatus for dequantizing and inverse transforming a color image to decode a residual transformed color image in any estimation mode.
  • the present invention also provides a method and an apparatus for decoding a color image using the method and the apparatus for dequantizing and inverse transforming the color image.
  • a method of transforming and quantizing a color image including: transforming a color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and quantizing the frequency domain image from which the redundancy has been removed.
  • QpBdOffsetc 6*bit_depth_chroma_minus8; and quantizing the transformed color image data using the QP'c.
  • an apparatus for transforming and quantizing a color image including: a domain transformer transforming a color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and a quantizer quantizing the frequency domain image from which the redundancy has been removed.
  • QpBdOffsetc 6*bit_depth_chroma_minus8; and a color image quantizer quantizing the transformed color image data using the QP'c.
  • a method of encoding a color image including: temporally (inter) and spatially (intra) estimating an input color image; residual transforming the estimated color image; transforming the color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and an estimation mode; quantizing the frequency domain image from which the redundancy has bee removed; and entropy encoding the quantized data.
  • an apparatus for encoding a color image including: an estimator temporally (inter) and spatially (intra) estimating an input color image; a residual transformer residual transforming the estimated color image; a domain transformer transforming the color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; a quantizer quantizing the frequency domain image from which the redundancy has bee removed; and an entropy encoder entropy encoding the quantized data.
  • a method of dequantizing and inverse transforming a color image including: differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized color image data; and differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
  • QpBdOffsetc 6*bit_depth_chroma_minus8; and dequantizing the transformed color image data using the QP'c.
  • the frequency transformation may be an integer inverse transformation of H.264 or an IDCT of MPEG.
  • an apparatus for dequantizing and inverse transforming a color image including: a de- quantizer differently setting a quantization parameter of a chrominance component depending on whether quantized color image data is residual transformed to dequantize the quantized color image data; and a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of a color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
  • the frequency inverse transformation performed by the domain inverse transformer is an integer inverse transformation of H.264 or an IDCT of MPEG.
  • a method of decoding a color image including: entropy decoding encoded color image data to recover quantized data; differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the de- quantized data; residual inverse transforming the frequency inverse transformed data; and performing intra and inter estimation compensations with respect to the residual inverse transformed data.
  • an apparatus for decoding a color image including: an entropy decoder entropy decoding encoded color image data to recover quantized data; a dequantizer differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and a macroblock estimation mode to frequency inverse transform the de- quantized data; a residual inverse transformer residual inverse transforming the frequency inverse transformed data; and an estimation compensator performing intra and inter estimation compensations with respect to the residual inverse transformed data.
  • a residual transformation can be applied regardless of an inter or intra estimation mode.
  • compression efficiency can be improved.
  • a quantization appropriate for the residual transformation can be performed. As a result, compression efficiency can be improved.
  • FIG. 1 is a block diagram of an apparatus for transforming and quantizing a color image according to an embodiment of the present invention
  • FIG. 2 is a block diagram of a redundancy remover shown in FIG. 1 ;
  • FIG. 3 is a block diagram of a quantizer shown in FIG. 1 ;
  • FIG. 4 is a flowchart of a method of transforming and quantizing a color image according to an embodiment of the present invention
  • FIG. 5 is a flowchart of operation 430 of the method of FIG. 4;
  • FIG. 6 is a flowchart of operation 460 of the method of FIG. 4;
  • FIG. 7 is a block diagram of an apparatus for encoding a color image using the apparatus for transforming and quantizing the color image according to an embodiment of the present invention
  • FIG. 8 is a flowchart of a method of encoding a color image using the method of transforming and quantizing the color image according to an embodiment of the present invention
  • FIG. 9 is a block diagram of an apparatus for dequantizing and inverse transforming a color image according to an embodiment of the present invention
  • FIG. 10 is a block diagram of a dequantizer shown in FIG. 9;
  • FIG. 11 is a block diagram of an inverse transformer shown in FIG. 9;
  • FIG. 12 is a flowchart of a method of dequantizing and inverse transforming a color image according to an embodiment of the present invention
  • FIG. 13 is a flowchart of a dequantization of the color image shown in FIG. 12;
  • FIG. 14 is a flowchart of an inverse transformation of the color image shown in
  • FIG. 1 is a block diagram of an apparatus for transforming and quantizing a color image according to an embodiment of the present invention.
  • the apparatus includes a domain transformer 100, a redundancy remover 130, and a quantizer 160.
  • the domain transformer 100 transforms a color image into a frequency domain image.
  • the redundancy remover 130 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode.
  • FIG. 2 is a block diagram of the redundancy remover 130 shown in FIG. 1. Referring to FIG. 2, the redundancy remover 130 includes a DC value transformer 200 and a Hadamard transformer 250.
  • the DC value transformer 200 quadruplicates a 4x4 DC value matrix obtained from the result of the frequency trans ⁇ formation as in Equation 1 ;
  • the quantizer 160 quantizes the frequency domain image from which the redundancy has been removed.
  • FIG. 3 is a block diagram of the quantizer 160 shown in FIG. 1.
  • the quantizer 160 includes a first quantization parameter transformer 300, a second quantization parameter transformer 320, and a color image quantizer 340.
  • the first quantizer parameter transformer 300 represents a quantization parameter of a chrominance component as in Equation 3:
  • QpBdOffsetc 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes an offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel.
  • the second quantization parameter transformer 320 represents the quantization parameter of the chrominance component as in Equation 4:
  • the color image quantizer 340 quantizes the transformed color image data using the QP'c.
  • FIG. 4 is a flowchart of a method of transforming and quantizing a color image according to an embodiment of the present invention. A method and an apparatus for transforming and quantizing a color image according to an embodiment of the present invention will now be described with reference to FIGS. 3 and 4.
  • the domain transformer 100 transforms a color image into a frequency domain image.
  • the redundancy remover 130 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode.
  • FIG. 5 is a flowchart of operation 430 of the method of FIG. 4.
  • the DC value transformer 200 quadruplicates a 4x4 DC value matrix obtained from the result of the frequency transformation as in Equation 1 above in operation 540.
  • the Hadamard transformer 250 Hadamard-transforms the 4x4 DC value matrix in operation 560.
  • the quantizer 160 quantizes the frequency domain image from which the redundancy of the DC components has been removed, in operation 460.
  • the second quantization parameter transformer 320 represents the quantization parameter of the chrominance component as in Equation 4 above in operation 640.
  • the color image quantizer 340 quantizes the transformed color image data using the QP'c in operation 660.
  • FIG. 7 is a block diagram of an apparatus for encoding a color image using the apparatus for transforming and quantizing the color image.
  • the apparatus includes a temporal and spatial estimator 700, a residual transformer 710, a transformer and quantizer 70, and an entropy encoder 750.
  • the temporal and spatial estimator 700 temporally (inter) and spatially (intra) estimates an input color image.
  • the residual transformer 710 residual transforms the estimated color image.
  • the transformer and quantizer 70 is the same as the apparatus for transforming and quantizing the color image and includes a domain transformer 720, a redundancy remover 730, and a quantizer 740.
  • the domain transformer 720 transforms the color image into a frequency domain image and is the same as the domain transformer 100 shown in FIG. 1.
  • the redundancy remover 730 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode and is the same as the redundancy remover 130 shown in FIG. 1.
  • the quantizer 740 quantizes the frequency domain image from which the redundancy has been removed and is the same as the quantizer 160 shown in FIG. 1.
  • the entropy encoder 750 entropy-encodes the quantized data.
  • FIG. 8 is a flowchart of a method of encoding a color image using the method of transforming and quantizing the color image according to an embodiment of the present invention.
  • the method of encoding the color image will be described with reference to FIGS. 7 and 8.
  • the temporal and spatial estimator 700 receives and temporally (inter) and spatially (intra) estimates a color image.
  • the residual transformer 710 residual transforms the estimated color image.
  • the domain transformer 720 transforms the color image into a frequency domain image.
  • the redundancy remover 730 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode.
  • the quantizer 740 quantizes the frequency domain image from which the redundancy has been removed.
  • the entropy encoder 750 entropy-encodes the quantized data. Operations 820, 830, and 840 are the same as those of the method of transforming and quantizing the color image, and thus their detailed description will be omitted.
  • FIG. 9 is a block diagram of an apparatus for dequantizing and inverse transforming a color image according to an embodiment of the present invention.
  • the apparatus includes a dequantizer 900 and a frequency inverse transformer 950.
  • the dequantizer 900 differently sets a quantization parameter of a chrominance component depending on whether quantized color image data is residual transformed to dequantize the quantized color image data.
  • FIG. 10 is a block diagram of the de- quantizer 900 shown in FIG. 9.
  • the second de- quantization parameter transformer 1020 represents the quantization parameter of the chrominance as in Equation 4 above.
  • the color image dequantizer 1040 dequantizes the transformed color image data using the QP'c.
  • the inverse transformer 950 differently performs a recovery of a redundancy of
  • FIG. 11 is a block diagram of the inverse transformer 950 shown in FIG. 10.
  • the inverse transformer 950 includes a DC value inverse transformer 1100, a Hadamard inverse transformer 1120, and a domain inverse transformer 1140.
  • the DC value inverse transformer 1100 quadruplicates a transformed 4x4 DC value matrix obtained from entropy decoded color image data as in Equation 1 above.
  • the Hadamard inverse transformer 1120 Hadamard inverse transforms the transformed 4x4 DC value matrix.
  • the domain inverse transformer 1140 frequency inverse transforms the result value of the DV value inverse transformer 1100 or the Hadamard inverse transformer 1120 and an alternating current (AC) value recovered from the entropy decoded color image data.
  • the frequency inverse transformation may be integer inverse transformation in H.264 but IDCT in MPEG.
  • FIG. 12 is a flowchart of a method of dequantizing and inverse transforming a color image according to an embodiment of the present invention. A method and an apparatus for dequantizing and inverse transforming a color image will now be described with reference to FIGS. 11 and 12.
  • the dequantizer 900 differently sets a quantization parameter of a chrominance component depending on whether the quantized color image data is residual transformed to dequantize the quantized color image data in operation 1200.
  • the frequency inverse transformer 950 differently performs a recovery of a redundancy of DC components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
  • the Hadamard inverse transformer 1120 Hadamard inverse transforms the transformed 4x4 DC value matrix in operation 1460.
  • the domain inverse transformer 1140 frequency inverse transforms the result value of operation 1440 or 1460 and an AC value recovered from the entropy decoded color image data.
  • the frequency inverse transformation may be integer inverse transformation in H.264 or IDCT in MPEG.
  • FIG. 15 is a block diagram of an apparatus for decoding a color image using the apparatus for de- quantizing and inverse transforming the color image according to an embodiment of the present invention.
  • the apparatus includes an entropy decoder 1500, a dequantizer and inverse transformer 15, a residual inverse transformer 1560, and an estimation compensator 1580.
  • the entropy decoder 1500 entropy decodes encoded color image data to recover quantized data.
  • the dequantizer and inverse transformer 15 is the same as the apparatus for de- quantizing and inverse transforming the color image and includes a dequantizer 1520 and a frequency inverse transformer 1540.
  • the dequantizer 1520 differently sets a quantization parameter of a chrominance component depending on whether the quantization data is residual transformed to dequqntize the quantized data.
  • the de- quantizer 1520 is also the same as the dequantizer 900 shown in FIG. 9, and thus its detailed description will be omitted.
  • the frequency inverse transformer 1540 differently performs a recovery of a redundancy of DC components of a color image depending on whether the color image is residual transformed and a macroblock estimation mode to frequency inverse transform the dequantized data.
  • the frequency inverse transformer 1540 is also the same as the frequency inverse transformer 950 shown in FIG. 9, and thus its detailed description will be omitted.
  • the residual inverse transformer 1560 residual inverse transforms the frequency inverse transformed data.
  • the estimation compensator 1580 performs intra and inter estimation compensations with respect to the residual inverse transformed data.
  • FIG. 16 is a flowchart of a method of decoding a color image using the method of dequantizing and inverse transforming the color image according to an embodiment of the present invention.
  • the entropy decoder 1500 entropy decodes the encoded color image data to recover quantized data.
  • the dequantizer 152 differently sets a quantization parameter of a chrominance component depending on whether a color image is residual transformed to dequantize the quantized data.
  • the frequency inverse transformer 1540 differently performs a recovery of a redundancy of DC components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
  • the residual inverse transformer 1560 residual inverse transforms the frequency inverse transformed data.
  • the estimation compensator 1580 performs intra and inter estimation compensations with respect to the residual inverse transformed data.
  • Operations 1620 and 1640 are the same as those of the method of dequantizing and inverse transforming the color image shown in FIG. 12, and thus their detailed de ⁇ scription will be omitted.

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Abstract

Provided are a method and an apparatus for transforming/inverse transforming and quantizing/dequantizing a color image and a method and an apparatus for encoding/decoding a color image using the method and the apparatus. The method of transforming and quantizing the color image includes; transforming a color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and quantizing the frequency domain image from which the redundancy has been removed.

Description

Description
METHODANDAPPARATUSTOTRANSFORM/INVERSE
TRANSFORMANDQUANTIZE/DEQUANTIZECOLOR
IMAGE,ANDMETHODANDAPPARATUSTO ENCODE/
DECODECOLORIMAGEUSINGIT
Technical Field
[1] The present invention relates to encoding and decoding of a color image, and more particularly, to a method and an apparatus for transforming/inverse transforming and quantizing/dequantizing a residual transformed color image and a method and an apparatus for encoding/decoding the color image using the same .
Background Art
[2] In general, a color image is color transformed and then encoded. Types of color coordinate systems are various. A standard coordinate system is an RGB coordinate system. An RGB image is transformed into an YCbCr image, divided into luminance and chrominance components, and encoded. As a result, since a redundancy of the chrominance components is removed by the transformation, encoding efficiency is increased. In particular, an integer transformation method using a lifting method has been studied. For example, YCoCg-R is developed by Microsoft Corporation.
[3] When a transformed image is encoded, temporal and spatial estimations are performed to remove the redundancy of components so as to obtain a residual image.
[4] In 'Text of ISO/IEC FDIS 14496-10: Information Technology - Coding of audio¬ visual objects - Part 10: Advanced Video Coding', ISO/IEC JTC 1/SC 29/WG 11, N5555, March, 2003 that is H.264/MPEG-4 pt.lO AVC standard technology of Joint Video Team (JVT) of ISO/IEC MPEG and ITU-T VCEG, spatial and temporal estimation encoding is performed using various methods to improve encoding efficiency. However, in a case where temporal and spatial estimations are performed with respect to chrominance components using the same method, a redundancy exists between residual images of chrominance components. To solve this, the residue images of the chrominance components are formed through the temporal and spatial estimations during encoding and transformation is performed with respect to the residue of the chrominance components so as to remove the redundancy of the residue of the chrominance components. Disclosure of Invention
Technical Problem
[5] However, in this case, a residual transformation method cannot be used respect to intra 4x4 and 8x8 blocks. This is because the use of the residual transformation method can not direct current (DC) transformation, thus it makes quantization inefficient. Thus, the residual transformation method is inefficient in terms of compression efficiency.
Technical Solution
[6] The present invention provides a method and an apparatus for quantizing and transforming a color image by which a residual transformation can be applied in any estimation mode to encode the color image.
[7] The present invention also provides a method and an apparatus for encoding a color image using the method and the apparatus for quantizing and transforming the color image.
[8] The present invention also provides a method and an apparatus for dequantizing and inverse transforming a color image to decode a residual transformed color image in any estimation mode.
[9] The present invention also provides a method and an apparatus for decoding a color image using the method and the apparatus for dequantizing and inverse transforming the color image.
[10] According to an aspect of the present invention, there is provided a method of transforming and quantizing a color image, including: transforming a color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and quantizing the frequency domain image from which the redundancy has been removed.
[11] Differently applying the transformation for removing the redundancy of the direct current components of the frequency domain image depending on whether the color image is residual transformed and the macroblock estimation mode may include: if in¬ formation residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below; and
[12] f = c «2 (where, i,j = 0...3)
IJ 1J
[13] if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard- transforming the 4x4 direct current value matrix. Quantizing the frequency domain image from which the redundancy has been removed may include: if the information residual_colour_transform_flag indicates the performance of the residual trans¬ formation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below:
[14] QP'c = QPc + QpBdOffsetc
[15] wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0, rep¬ resenting the quantization parameter of the chrominance component as in Equation below:
[16] QP'c = QPc + QpBdOffsetc
[17] wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and quantizing the transformed color image data using the QP'c.
[18] According another aspect of the present invention, there is provided an apparatus for transforming and quantizing a color image, including: a domain transformer transforming a color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and a quantizer quantizing the frequency domain image from which the redundancy has been removed.
[19] The redundancy remover may include: if information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, a direct current value transformer quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below; and
[20] f = c «2 (where, i,j = 0...3)
IJ 1J
[21] if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, a Hadamard transformer Hadamard-transforming the 4x4 direct current value matrix. The quantizer may include: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l, a first quantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below:
[22] QP'c = QPc + QpBdOffsetc
[23] wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0, a second quantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below:
[24] QP'c = QPc + QpBdOffsetc
[25] wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and a color image quantizer quantizing the transformed color image data using the QP'c.
[26] According to still another aspect of the present invention, there is provided a method of encoding a color image, including: temporally (inter) and spatially (intra) estimating an input color image; residual transforming the estimated color image; transforming the color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and an estimation mode; quantizing the frequency domain image from which the redundancy has bee removed; and entropy encoding the quantized data.
[27] According yet another aspect of the present invention, there is provided an apparatus for encoding a color image, including: an estimator temporally (inter) and spatially (intra) estimating an input color image; a residual transformer residual transforming the estimated color image; a domain transformer transforming the color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; a quantizer quantizing the frequency domain image from which the redundancy has bee removed; and an entropy encoder entropy encoding the quantized data.
[28] According to yet another aspect of the present invention, there is provided a method of dequantizing and inverse transforming a color image, including: differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized color image data; and differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
[29] Dequantizing the quantized color image may include: if information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below:
[30] QP'c = QPc + QpBdOffsetc
[31] wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates a non- performance of the residual transformation residual_colour_transform_flag=0, rep¬ resenting the quantization parameter of the chrominance component as in Equation below:
[32] QP'c = QPc + QpBdOffsetc
[33] wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and dequantizing the transformed color image data using the QP'c.
[34] Frequency inverse transforming the dequantized data may include: if the in¬ formation residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, quadruplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image data as in Equation below;
[35] f = c «2 (where, i,j = 0...3)
IJ 1J
[36] if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard inverse transforming the transformed 4x4 direct current value matrix; and frequency inverse transforming the result value of the quadruplication or the Hadamard inverse transformation and an alternating current value recovered from the entropy decoded color image. The frequency transformation may be an integer inverse transformation of H.264 or an IDCT of MPEG.
[37] According to yet another aspect of the present invention, there is provided an apparatus for dequantizing and inverse transforming a color image, including: a de- quantizer differently setting a quantization parameter of a chrominance component depending on whether quantized color image data is residual transformed to dequantize the quantized color image data; and a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of a color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
[38] The dequantizer may include: if information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l, a first dequantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below:
[39] QP'c = QPc + QpBdOffsetc
[40] wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates a non- performance of the residual transformation residual_colour_transform_flag=0, a second dequantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below:
[41 ] QP'c = QPc + QpBdOffsetc ... (4)
[42] wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and a color image de- quantizer dequantizing the transformed color image data using the QP'c. The frequency inverse transformer may include: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, a direct current value inverse transformer quadruplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image as in Equation below;
[43] f = c «2 (where, i,j = 0...3)
IJ 1J
[44] if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, a Hadamard inverse transformer Hadamard inverse transforming the transformed 4x4 direct current value matrix; and a domain inverse transformer frequency inverse transforming the result value of the direct current value inverse transformer or the Hadamard inverse transformer and an alternating current value recovered from the entropy decoded color image. The frequency inverse transformation performed by the domain inverse transformer is an integer inverse transformation of H.264 or an IDCT of MPEG.
[45] According to yet another aspect of the present invention, there is provided a method of decoding a color image, including: entropy decoding encoded color image data to recover quantized data; differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the de- quantized data; residual inverse transforming the frequency inverse transformed data; and performing intra and inter estimation compensations with respect to the residual inverse transformed data.
[46] According to yet another aspect of the present invention, there is provided an apparatus for decoding a color image, including: an entropy decoder entropy decoding encoded color image data to recover quantized data; a dequantizer differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and a macroblock estimation mode to frequency inverse transform the de- quantized data; a residual inverse transformer residual inverse transforming the frequency inverse transformed data; and an estimation compensator performing intra and inter estimation compensations with respect to the residual inverse transformed data.
[47] According to yet another aspect of the present invention, there is provided a computer readable recording medium having embodied one of the methods as a computer program thereon.
Advantageous Effects
[48] As described above, in a method and an apparatus for quantizing/dequantizing and transforming/inverse transforming a color image and a method and an apparatus for encoding/decoding a color image using the method and the apparatus according to the present invention, a residual transformation can be applied regardless of an inter or intra estimation mode. Thus, compression efficiency can be improved. Also, a quantization appropriate for the residual transformation can be performed. As a result, compression efficiency can be improved. Description of Drawings
[49] FIG. 1 is a block diagram of an apparatus for transforming and quantizing a color image according to an embodiment of the present invention; [50] FIG. 2 is a block diagram of a redundancy remover shown in FIG. 1 ;
[51] FIG. 3 is a block diagram of a quantizer shown in FIG. 1 ;
[52] FIG. 4 is a flowchart of a method of transforming and quantizing a color image according to an embodiment of the present invention; [53] FIG. 5 is a flowchart of operation 430 of the method of FIG. 4;
[54] FIG. 6 is a flowchart of operation 460 of the method of FIG. 4;
[55] FIG. 7 is a block diagram of an apparatus for encoding a color image using the apparatus for transforming and quantizing the color image according to an embodiment of the present invention; [56] FIG. 8 is a flowchart of a method of encoding a color image using the method of transforming and quantizing the color image according to an embodiment of the present invention; [57] FIG. 9 is a block diagram of an apparatus for dequantizing and inverse transforming a color image according to an embodiment of the present invention; [58] FIG. 10 is a block diagram of a dequantizer shown in FIG. 9;
[59] FIG. 11 is a block diagram of an inverse transformer shown in FIG. 9;
[60] FIG. 12 is a flowchart of a method of dequantizing and inverse transforming a color image according to an embodiment of the present invention;
[61] FIG. 13 is a flowchart of a dequantization of the color image shown in FIG. 12;
[62] FIG. 14 is a flowchart of an inverse transformation of the color image shown in
FIG. 12; [63] FIG. 15 is a block diagram of an apparatus for decoding a color image using the apparatus for dequantizing and inverse transforming the color image according to an embodiment of the present invention; and [64] FIG. 16 is a flowchart of a method of decoding a color image using the method of dequantizing and inverse transforming the color image according to an embodiment of the present invention.
Mode for Invention [65] Hereinafter, a method and an apparatus for transforming/inverse transforming and quantizing/dequantizing a color image that is residual transformed, and a method and an apparatus for encoding/decoding a color image using the method and apparatus will be described in detail with reference to the attached drawings. [66] FIG. 1 is a block diagram of an apparatus for transforming and quantizing a color image according to an embodiment of the present invention. Referring to FIG. 1, the apparatus includes a domain transformer 100, a redundancy remover 130, and a quantizer 160.
[67] The domain transformer 100 transforms a color image into a frequency domain image. [68] The redundancy remover 130 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode. FIG. 2 is a block diagram of the redundancy remover 130 shown in FIG. 1. Referring to FIG. 2, the redundancy remover 130 includes a DC value transformer 200 and a Hadamard transformer 250. In a case where information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, the DC value transformer 200 quadruplicates a 4x4 DC value matrix obtained from the result of the frequency trans¬ formation as in Equation 1 ;
[69] f = c «2 (where, ij = 0...3) ...(l)
IJ 1J [70] In a case where the information residual_colour_transform_flag indicates a non- performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8 , the Hadamard transformer 250 Hadamard-transforms the 4x4 DC value matrix as in Equation 2:
[71]
1 1 1 1] '00 '01 '02 '03 1 1 1 1
1 1 -1 - 1 '10 ' 11 '12 ' 13 1 1 - 1 - 1
/ =
1 -1 -1 1 '.0 ' 21 ' 22 '23 1 - 1 - 1 1
1 1 1 -lj '30 ' 31 '32 '33 1 - 1 1 - 1
...(2)
[72] The quantizer 160 quantizes the frequency domain image from which the redundancy has been removed. FIG. 3 is a block diagram of the quantizer 160 shown in FIG. 1. Referring to FIG. 3, the quantizer 160 includes a first quantization parameter transformer 300, a second quantization parameter transformer 320, and a color image quantizer 340. In a case where the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l, the first quantizer parameter transformer 300 represents a quantization parameter of a chrominance component as in Equation 3:
[73] QP'c = QPc + QpBdOffsetc ... (3)
[74] wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes an offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel.
[75] In a case where the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0, the second quantization parameter transformer 320 represents the quantization parameter of the chrominance component as in Equation 4:
[76] QP'c = QPc + QpBdOffsetc ... (4)
[77] wherein QpBdOffsetc = 6*bit_depth_chroma_minus8.
[78] The color image quantizer 340 quantizes the transformed color image data using the QP'c.
[79] FIG. 4 is a flowchart of a method of transforming and quantizing a color image according to an embodiment of the present invention. A method and an apparatus for transforming and quantizing a color image according to an embodiment of the present invention will now be described with reference to FIGS. 3 and 4.
[80] In operation 400, the domain transformer 100 transforms a color image into a frequency domain image. In operation 430, the redundancy remover 130 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode. FIG. 5 is a flowchart of operation 430 of the method of FIG. 4. If information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual trans¬ formation residual_colour_transform_flag=l in operation 500 and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8 in operation 520, the DC value transformer 200 quadruplicates a 4x4 DC value matrix obtained from the result of the frequency transformation as in Equation 1 above in operation 540.
[81] If the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 in operation 500 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8 in operation 520, the Hadamard transformer 250 Hadamard-transforms the 4x4 DC value matrix in operation 560.
[82] If the redundancy of the DC components is removed in operation 430, the quantizer 160 quantizes the frequency domain image from which the redundancy of the DC components has been removed, in operation 460. FIG. 6 is a flowchart of operation 460 of the method of FIG. 4. If the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l in operation 600, the first quantization parameter transformer 300 represents a quantization parameter of a chrominance component as in Equation 3 above in operation 620. If the information residual_colour_transform_flag indicates the non-performance of the residual trans¬ formation residual_colour_transform_flag=0 in operation 600, the second quantization parameter transformer 320 represents the quantization parameter of the chrominance component as in Equation 4 above in operation 640. The color image quantizer 340 quantizes the transformed color image data using the QP'c in operation 660.
[83] An apparatus and a method for encoding a color image using the apparatus and the method for transforming and quantizing the color image will now be described. FIG. 7 is a block diagram of an apparatus for encoding a color image using the apparatus for transforming and quantizing the color image. Referring to FIG. 7, the apparatus includes a temporal and spatial estimator 700, a residual transformer 710, a transformer and quantizer 70, and an entropy encoder 750. The temporal and spatial estimator 700 temporally (inter) and spatially (intra) estimates an input color image. The residual transformer 710 residual transforms the estimated color image. The transformer and quantizer 70 is the same as the apparatus for transforming and quantizing the color image and includes a domain transformer 720, a redundancy remover 730, and a quantizer 740. The domain transformer 720 transforms the color image into a frequency domain image and is the same as the domain transformer 100 shown in FIG. 1. The redundancy remover 730 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode and is the same as the redundancy remover 130 shown in FIG. 1. The quantizer 740 quantizes the frequency domain image from which the redundancy has been removed and is the same as the quantizer 160 shown in FIG. 1. The entropy encoder 750 entropy-encodes the quantized data.
[84] FIG. 8 is a flowchart of a method of encoding a color image using the method of transforming and quantizing the color image according to an embodiment of the present invention. The method of encoding the color image will be described with reference to FIGS. 7 and 8. In operation 800, the temporal and spatial estimator 700 receives and temporally (inter) and spatially (intra) estimates a color image. In operation 810, the residual transformer 710 residual transforms the estimated color image. In operation 820, the domain transformer 720 transforms the color image into a frequency domain image. In operation 830, the redundancy remover 730 differently applies a transformation for removing a redundancy of DC components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode. In operation 840, the quantizer 740 quantizes the frequency domain image from which the redundancy has been removed. In operation 850, the entropy encoder 750 entropy-encodes the quantized data. Operations 820, 830, and 840 are the same as those of the method of transforming and quantizing the color image, and thus their detailed description will be omitted.
[85] An apparatus and a method for dequantizing and inverse transforming a color image according to an embodiment of the present invention will now be described. FIG. 9 is a block diagram of an apparatus for dequantizing and inverse transforming a color image according to an embodiment of the present invention. Referring to FIG. 9, the apparatus includes a dequantizer 900 and a frequency inverse transformer 950.
[86] The dequantizer 900 differently sets a quantization parameter of a chrominance component depending on whether quantized color image data is residual transformed to dequantize the quantized color image data. FIG. 10 is a block diagram of the de- quantizer 900 shown in FIG. 9. Referring to FIG. 10, the dequantizer 900 includes a first dequantization parameter transformer 1000, a second dequantization parameter transformer 1020, and a color image dequantizer 1040. If information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l, the first dequantization parameter transformer 1000 represents the quantization parameter of the chrominance as in Equation 3 above. If the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0, the second de- quantization parameter transformer 1020 represents the quantization parameter of the chrominance as in Equation 4 above. The color image dequantizer 1040 dequantizes the transformed color image data using the QP'c.
[87] The inverse transformer 950 differently performs a recovery of a redundancy of
DC components of the color image depending on whether the dequantized data is residual transformed and a macroblock estimation mode to frequency inverse transform the dequantized data. FIG. 11 is a block diagram of the inverse transformer 950 shown in FIG. 10. Referring to FIG. 11, the inverse transformer 950 includes a DC value inverse transformer 1100, a Hadamard inverse transformer 1120, and a domain inverse transformer 1140. If information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, the DC value inverse transformer 1100 quadruplicates a transformed 4x4 DC value matrix obtained from entropy decoded color image data as in Equation 1 above.
[88] If the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, the Hadamard inverse transformer 1120 Hadamard inverse transforms the transformed 4x4 DC value matrix.
[89] The domain inverse transformer 1140 frequency inverse transforms the result value of the DV value inverse transformer 1100 or the Hadamard inverse transformer 1120 and an alternating current (AC) value recovered from the entropy decoded color image data. The frequency inverse transformation may be integer inverse transformation in H.264 but IDCT in MPEG.
[90] FIG. 12 is a flowchart of a method of dequantizing and inverse transforming a color image according to an embodiment of the present invention. A method and an apparatus for dequantizing and inverse transforming a color image will now be described with reference to FIGS. 11 and 12.
[91] If quantized color image data is input to the dequantizer 900, the dequantizer 900 differently sets a quantization parameter of a chrominance component depending on whether the quantized color image data is residual transformed to dequantize the quantized color image data in operation 1200.
[92] In operation 1250, the frequency inverse transformer 950 differently performs a recovery of a redundancy of DC components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
[93] FIG 13 is a flowchart of operation 100 of the method of FIG 12. If information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l in operation 1300, the first dequantization parameter transformer 1000 represents a quantization parameter of a chrominance component as in Equation 3 above in operation 1320. If the information residual_colour_transform_flag indicates a non-performance of the residual trans¬ formation residual_colour_transform_flag=0 in operation 1300, the second de- quantization parameter transformer 1020 represents the quantization parameter of the chrominance component as in Equation 4 above in operation 1340. In operation 1360, the color image dequantizer 1040 dequantizes the transformed color image data using the QP'c.
[94] FIG. 14 is a flowchart of operation 1250 of the method of FIG. 12. If the in¬ formation residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l in operation 1400 and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8 in operation 1420, the DC value inverse transformer 1100 quadruplicates a transformed 4x4 DC value matrix obtained from entropy decoded color image data as in Equation 1 above in operation 1440. If the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0 in operation 1400 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8 in operation 1420, the Hadamard inverse transformer 1120 Hadamard inverse transforms the transformed 4x4 DC value matrix in operation 1460. In operation 1480, the domain inverse transformer 1140 frequency inverse transforms the result value of operation 1440 or 1460 and an AC value recovered from the entropy decoded color image data. The frequency inverse transformation may be integer inverse transformation in H.264 or IDCT in MPEG.
[95] An apparatus and a method for decoding a color image using the apparatus for de- quantizing and inverse transforming the color image will now be described. FIG. 15 is a block diagram of an apparatus for decoding a color image using the apparatus for de- quantizing and inverse transforming the color image according to an embodiment of the present invention. Referring to FIG. 15, the apparatus includes an entropy decoder 1500, a dequantizer and inverse transformer 15, a residual inverse transformer 1560, and an estimation compensator 1580.
[96] The entropy decoder 1500 entropy decodes encoded color image data to recover quantized data.
[97] The dequantizer and inverse transformer 15 is the same as the apparatus for de- quantizing and inverse transforming the color image and includes a dequantizer 1520 and a frequency inverse transformer 1540. The dequantizer 1520 differently sets a quantization parameter of a chrominance component depending on whether the quantization data is residual transformed to dequqntize the quantized data. The de- quantizer 1520 is also the same as the dequantizer 900 shown in FIG. 9, and thus its detailed description will be omitted. The frequency inverse transformer 1540 differently performs a recovery of a redundancy of DC components of a color image depending on whether the color image is residual transformed and a macroblock estimation mode to frequency inverse transform the dequantized data. The frequency inverse transformer 1540 is also the same as the frequency inverse transformer 950 shown in FIG. 9, and thus its detailed description will be omitted.
[98] The residual inverse transformer 1560 residual inverse transforms the frequency inverse transformed data. The estimation compensator 1580 performs intra and inter estimation compensations with respect to the residual inverse transformed data.
[99] FIG. 16 is a flowchart of a method of decoding a color image using the method of dequantizing and inverse transforming the color image according to an embodiment of the present invention.
[100] If encoded color image data is input to the entropy decoder 1500, in operation
1600, the entropy decoder 1500 entropy decodes the encoded color image data to recover quantized data. In operation 1620, the dequantizer 152 differently sets a quantization parameter of a chrominance component depending on whether a color image is residual transformed to dequantize the quantized data. In operation 1640, the frequency inverse transformer 1540 differently performs a recovery of a redundancy of DC components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data. In operation 1660, the residual inverse transformer 1560 residual inverse transforms the frequency inverse transformed data. In operation 1680, the estimation compensator 1580 performs intra and inter estimation compensations with respect to the residual inverse transformed data.
[101] Operations 1620 and 1640 are the same as those of the method of dequantizing and inverse transforming the color image shown in FIG. 12, and thus their detailed de¬ scription will be omitted.

Claims

Claims
[1] A method of transforming and quantizing a color image, comprising: transforming a color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and quantizing the frequency domain image from which the redundancy has been removed.
[2] The method of claim 1, wherein differently applying the transformation for removing the redundancy of the direct current components of the frequency domain image depending on whether the color image is residual transformed and the macroblock estimation mode comprises: if information residual_colour_transform_flag as to whether a residual trans¬ formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below; and f = c «2 (where, i,j = 0...
3)
IJ 1J if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard-transforming the 4x4 direct current value matrix. [3] The method of claim 1 or 2, wherein quantizing the frequency domain image from which the redundancy has been removed comprises: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0, representing the quantization parameter of the chrominance component as in
Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and quantizing the transformed color image data using the QP'c.
[4] An apparatus for transforming and quantizing a color image, comprising: a domain transformer transforming a color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; and a quantizer quantizing the frequency domain image from which the redundancy has been removed.
[5] The apparatus of claim 4, wherein the redundancy remover comprises: a direct current value transformer quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below, f = c «2 (where, i,j = 0...3)
IJ IJ
,if information residual_colour_transform_flag as to whether a residual trans¬ formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8; and a Hadamard transformer Hadamard-transforming the 4x4 direct current value matrix, if the information residual_colour_transform_flag indicates a non- performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8.
[6] The apparatus of claim 4 or 5, wherein the quantizer comprises: a first quantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel, if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l; a second quantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8, if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0; and a color image quantizer quantizing the transformed color image data using the
QP'c.
[7] A method of encoding a color image, comprising: temporally (inter) and spatially (intra) estimating an input color image; residual transforming the estimated color image; transforming the color image into a frequency domain image; differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and an estimation mode; quantizing the frequency domain image from which the redundancy has bee removed; and entropy encoding the quantized data.
[8] The method of claim 7, wherein differently applying the transformation for removing the redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and the estimation mode comprises: if information residual_colour_transform_flag as to whether a residual trans¬ formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below; and f = c «2 (where, i,j = 0...3)
IJ 1J if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra 4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard-transforming the 4x4 direct current value matrix.
[9] The method of claim 7 or 8, wherein quantizing the frequency domain image from which the redundancy has been removed comprises: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0, representing the quantization parameter of the chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and quantizing the transformed color image data using the QP'c.
[10] An apparatus for encoding a color image, comprising: an estimator temporally (inter) and spatially (intra) estimating an input color image; a residual transformer residual transforming the estimated color image; a domain transformer transforming the color image into a frequency domain image; a redundancy remover differently applying a transformation for removing a redundancy of direct current components of the frequency domain image depending on whether the color image is residual transformed and a macroblock estimation mode; a quantizer quantizing the frequency domain image from which the redundancy has bee removed; and an entropy encoder entropy encoding the quantized data.
[11] The apparatus of claim 10, wherein the redundancy remover comprises: a direct current value transformer quadruplicating a 4x4 direct current value matrix obtained from the result of the frequency transformation as in Equation below, f = c «2 (where, i,j = 0...3)
IJ IJ if information residual_colour_transform_flag as to whether a residual trans- formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l and the macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8; and a Hadamard transformer Hadamard-transforming the 4x4 direct current value matrix, if the information residual_colour_transform_flag indicates a non- performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8.
[12] The apparatus of claim 10 or 11, wherein the quantizer comprises: a first quantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of
QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel, if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l; a second quantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8, if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0; and a color image quantizer quantizing the transformed color image data using the
QP'c.
[13] A method of dequantizing and inverse transforming a color image, comprising: differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized color image data; and differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
[14] The method of claim 13, wherein dequantizing the quantized color image comprises: if information residual_colour_transform_flag as to whether a residual trans¬ formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0, representing the quantization parameter of the chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and dequantizing the transformed color image data using the QP'c.
[15] The method of claim 13 or 14, wherein frequency inverse transforming the de- quantized data comprises: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, qua¬ druplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image data as in Equation below; f = c «2 (where, i,j = 0...3)
IJ 1J if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard inverse transforming the transformed 4x4 direct current value matrix; and frequency inverse transforming the result value of the quadruplication or the Hadamard inverse transformation and an alternating current value recovered from the entropy decoded color image.
[16] The method of claim 15, wherein the frequency transformation is one of an integer inverse transformation of H.264 and an IDCT of MPEG.
[17] An apparatus for dequantizing and inverse transforming a color image, comprising: a dequantizer differently setting a quantization parameter of a chrominance component depending on whether quantized color image data is residual transformed to dequantize the quantized color image data; and a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of a color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data.
[18] The apparatus of claim 17, wherein the dequantizer comprises: a first dequantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of
QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel, if information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l ; a second dequantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below:
QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8, if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0; and a color image dequantizer dequantizing the transformed color image data using the QP'c.
[19] The apparatus of claim 17 or 18, wherein the frequency inverse transformer comprises: a direct current value inverse transformer quadruplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image as in Equation below; f = c «2 (where, i,j = 0...3)
IJ 1J if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8; a Hadamard inverse transformer Hadamard inverse transforming the transformed 4x4 direct current value matrix, if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8; and a domain inverse transformer frequency inverse transforming the result value of the direct current value inverse transformer or the Hadamard inverse transformer and an alternating current value recovered from the entropy decoded color image.
[20] The apparatus of claim 19, wherein the frequency inverse transformation performed by the domain inverse transformer is one of an integer inverse trans¬ formation of H.264 and an IDCT of MPEG.
[21] A method of decoding a color image, comprising: entropy decoding encoded color image data to recover quantized data; differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and an estimation mode to frequency inverse transform the dequantized data; residual inverse transforming the frequency inverse transformed data; and performing intra and inter estimation compensations with respect to the residual inverse transformed data.
[22] The method of claim 22, wherein dequantizing the quantized data comprises: if information residual_colour_transform_flag as to whether a residual trans¬ formation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l, representing a quantization parameter of a chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel; if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0, representing the quantization parameter of the chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8; and dequantizing the transformed color image data using the QP'c.
[23] The method of claim 21 or 22, wherein frequency inverse transforming the de- quantized data comprises: if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8, qua¬ druplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image data as in Equation below; f = c «2 (where, i,j = 0...3)
IJ 1J if the information residual_colour_transform_flag indicates the non- performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8, Hadamard inverse transforming the transformed 4x4 direct current value matrix; and frequency inverse transforming the result value of the quadruplication or the Hadamard inverse transformation and an alternating current value recovered from the entropy decoded color image data.
[24] The method of claim 23, wherein the frequency inverse transformation is one of an integer inverse transformation of H.264 and an IDCT of MPEG.
[25] An apparatus for decoding a color image, comprising: an entropy decoder entropy decoding encoded color image data to recover quantized data; a dequantizer differently setting a quantization parameter of a chrominance component depending on whether the color image is residual transformed to dequantize the quantized data; a frequency inverse transformer differently performing a recovery of a redundancy of direct current components of the color image depending on whether the color image is residual transformed and a macroblock estimation mode to frequency inverse transform the dequantized data; a residual inverse transformer residual inverse transforming the frequency inverse transformed data; and an estimation compensator performing intra and inter estimation compensations with respect to the residual inverse transformed data.
[26] The apparatus of claim 25, wherein the dequantizer comprises: a first dequantization parameter transformer representing a quantization parameter of a chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*(bit_depth_chroma_minus8 + residual_colour_transform_flag) and QPc denotes a quantization parameter of a chrominance component Cb, Cr, R, or B, where QpBdOffsetc denotes offset of QPc and bit_depth_chroma_minus8 denotes a bit depth of a chrominance array sample per pixel, if information residual_colour_transform_flag as to whether a residual transformation is performed indicates a performance of the residual transformation residual_colour_transform_flag=l ; a second dequantization parameter transformer representing the quantization parameter of the chrominance component as in Equation below: QP'c = QPc + QpBdOffsetc wherein QpBdOffsetc = 6*bit_depth_chroma_minus8, if the information residual_colour_transform_flag indicates a non-performance of the residual transformation residual_colour_transform_flag=0; and a color image dequantizer dequantizing the transformed color image data using the QP'c.
[27] The apparatus of claim 25 or 26, wherein the frequency inverse transformer comprises: a direct current value inverse transformer quadruplicating a transformed 4x4 direct current value matrix obtained from entropy decoded color image data as in Equation below, f = c «2 (where, i,j = 0...3)
IJ 1J if the information residual_colour_transform_flag indicates the performance of the residual transformation residual_colour_transform_flag=l and a macroblock estimation mode with respect to luma (Y or G component) is a 4x4 intra estimation mode Intra_4x4 or a 8x8 intra estimation mode Intra_8x8; a Hadamard inverse transformer Hadamard inverse transforming the transformed 4x4 direct current value matrix, if the information residual_colour_transform_flag indicates the non-performance of the residual transformation residual_colour_transform_flag=0 or the macroblock estimation mode with respect to the luma (Y or G component) is not both the 4x4 intra estimation mode Intra_4x4 and the 8x8 intra estimation mode Intra_8x8; and a domain inverse transformer frequency inverse transforming the result value of the direct current value inverse transformer or the Hadamard inverse transformer and an alternating current value recovered from the entropy decoded color image data.
[28] The apparatus of claim 27, wherein the frequency inverse transformation performed by the domain inverse transformer is one of an integer inverse trans¬ formation of H.264 and an IDCT of MPEG.
[29] A computer readable recording medium having embodied the method of one of claims 1, 7, 13, and 21 as a computer program thereon.
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