Image decoder, image encoder, and encoded data converter
The amount of encoding of hierarchically encoded data is reduced with an improvement in the accuracy of a predicted image by including information for accurate derivation of a position of a reference layer pixel corresponding to a pixel in a higher layer, which is a target layer, in the hierarchically encoded data. A hierarchical moving image decoder includes a parameter set decoding unit decoding inter-layer phase correspondence information and a predicted image generator generating a predicted image on the basis of the inter-layer phase correspondence information.
1. An image decoder for decoding hierarchically encoded data, the image decoder comprising:
parameter set decoding circuitry that decodes a parameter set including at least an inter-layer pixel correspondence offset of a reference layer corresponding region and a reference layer crop offset; and
reference position derivation circuitry that derives a reference layer phase offset by the reference layer crop offset and an inter-layer size ratio; wherein
the reference position derivation circuitry derives a corresponding reference position of a reference picture using (i) the reference layer phase offset, (ii) the inter-layer pixel correspondence offset, and (iii) the inter-layer size ratio by a following set of equations:
x Ref= x Ref Tmp +phaseOffset X,
y Ref= y Ref Tmp +phaseOffset Y,
xRefTmp and yRefTmp are determined by a following set of equations:
x Ref Tmp =( x P - SRL LeftOffset) * scale X,
y Ref Tmp =( y P - SRL TopOffset) * scale Y;
xRef represents a position of a corresponding reference pixel in a horizontal direction from a reference point of an upper left pixel of the reference picture;
yRef represents a position of the corresponding reference pixel in a vertical direction from the reference point of the upper left pixel of the reference picture;
xRefTmp represents a position from a reference point in a horizontal direction from an upper left pixel of a reference layer picture;
yRefTmp represents a position from the reference point in a vertical direction from the upper left pixel of the reference layer picture;
phaseOffsetX represents a horizontal component of the reference layer phase offset;
phaseOffsetY represents a vertical component of the reference layer phase off-set;
xP represents a horizontal component of a target layer pixel from a reference point of a upper left pixel of a target layer picture;
yP represent a vertical component of the target layer pixel from the reference point of the upper left pixel of the target layer picture;
scaleX represents a horizontal component of the inter-layer size ratio calculated by refPicW over SRLW, wherein refPicW denotes a width of the reference layer and SRLW denotes a width of the reference layer corresponding region;
scaleY represents a vertical component of the inter-layer size ratio calculated by refPicH over SRLH, wherein refPicH denotes a height of the reference layer and SRLH denotes a height of the reference layer corresponding region; and
SRLLeftOffset and SRLRightOffset represent the inter-layer pixel correspondence offset.
2. A method for decoding hierarchically encoded data, the method comprising:
decoding a parameter set including at least an inter-layer pixel correspondence offset of a reference layer corresponding region and a reference layer crop offset;
deriving a reference layer phase offset by the reference layer crop offset and an inter-layer size ratio; and
deriving a corresponding reference position of a reference picture using (i) the reference layer phase offset, (ii) the inter-layer pixel correspondence offset, and (iii) the inter-layer size ratio by a following set of equations:
x Ref= xRef Tmp +phaseOffset X,
y Ref= y Ref Tmp +phaseOffset Y,
xRefTmp and yRefTmp are determined by a following set of equations:
x Ref Tmp =( x P - SRL LeftOffset) * scale X,
Ref Tmp =( y P - SRL TopOffset) * scale Y;
xRef represents a position of a corresponding reference pixel in a horizontal direction from a reference point of an upper left pixel of the reference picture;
yRef represents a position of the corresponding reference pixel in a vertical direction from the reference point of the upper left pixel of the reference picture;
xRefTmp represents a position from a reference point in a horizontal direction from an upper left pixel of a reference layer picture;
yRefTmp represents a position from the reference point in a vertical direction from the upper left pixel of the reference layer picture;
phaseOffsetX represents a horizontal component of the reference layer phase offset;
phaseOffsetY represents a vertical component of the reference layer phase off-set;
xP represents a horizontal component of a target layer pixel from a reference point of a upper left pixel of a target layer picture;
yP represent a vertical component of the target layer pixel from the reference point of the upper left pixel of the target layer picture;
scaleX represents a horizontal component of the inter-layer size ratio calculated by refPicW over SRLW, wherein refPicW denotes a width of the reference layer and SRLW denotes a width of the reference layer corresponding region;
scaleY represents a vertical component of the inter-layer size ratio calculated by refPicH over SRLH, wherein refPicH denotes a height of the reference layer and SRLH denotes a height of the reference layer corresponding region; and
SRLLeftOffset and SRLRightOffset represent the inter-layer pixel correspondence offset.
3. An image encoder for encoding hierarchically encoded data, the image encoder comprising:
parameter set encoding circuitry that encodes a parameter set including at least an inter-layer pixel correspondence offset of a reference layer corresponding region and a
reference layer crop offset; and
reference position derivation circuitry that derives a reference layer phase offset by the reference layer crop offset and an inter-layer size ratio; wherein
the reference position derivation circuitry derives a corresponding reference position of a reference picture using (i) the reference layer phase offset, (ii) the inter-layer pixel correspondence offset, and (iii) the inter-layer size ratio by a following set of equations:
x Ref= x Ref Tmp +phaseOffset X,
y Ref= y Ref Tmp +phaseOffset Y,
xRefTmp and yRefTmp are determined by a following set of equations:
x Ref Tmp =( x P - SRL LeftOffset) * scale X,
y Ref Tmp =( y P - SRL TopOffset) * scale Y;
xRef represents a position of a corresponding reference pixel in a horizontal direction from a reference point of an upper left pixel of the reference picture;
yRef represents a position of the corresponding reference pixel in a vertical direction from the reference point of the upper left pixel of the reference picture;
xRefTmp represents a position from a reference point in a horizontal direction from an upper left pixel of a reference layer picture;
yRefTmp represents a position from the reference point in a vertical direction from the upper left pixel of the reference layer picture;
phaseOffsetX represents a horizontal component of the reference layer phase offset;
phaseOffsetY represents a vertical component of the reference layer phase off-set;
xP represents a horizontal component of a target layer pixel from a reference point of a upper left pixel of a target layer picture;
yP represent a vertical component of the target layer pixel from the reference point of the upper left pixel of the target layer picture;
scaleX represents a horizontal component of the inter-layer size ratio calculated by refPicW over SRLW, wherein refPicW denotes a width of the reference layer and SRLW denotes a width of the reference layer corresponding region;
scaleY represents a vertical component of the inter-layer size ratio calculated by refPicH over SRLH, wherein refPicH denotes a height of the reference layer and SRLH denotes a height of the reference layer corresponding region; and
SRLLeftOffset and SRLRightOffset represent the inter-layer pixel correspondence offset.