Patent ID: 6748018
Filing Date: 2004-06-08
Classification: H04N

Abstract:
A picture decoding apparatus for decoding compressed picture data of a first resolution, obtained on predictive coding by motion prediction in terms of a macro-block as a unit and on compression coding by orthogonal transform in terms of an orthogonal transform block as a unit, to obtain moving picture data of a second resolution being lower than the first resolution, comprising:first inverse orthogonal transform means for inverse orthogonal transforming an orthogonal transform block of the compressed picture data, orthogonal transformed by an orthogonal transform system in a field orthogonal transform mode associated with an interlaced scanning; second inverse orthogonal transform means for inverse orthogonal transforming an orthogonal transform block of said compressed picture data, orthogonal transformed in accordance with an orthogonal transform system in a frame orthogonal transform mode associated with a sequential scanning; first addition means for summing the compressed picture data, inverse orthogonal transformed by said first inverse orthogonal transform means or said second inverse orthogonal transform means, to motion compensated reference picture data, to output moving picture data of the second resolution; first memory means for storing moving picture data outputted by said first addition means as reference picture data; and first motion compensation means for motion compensating the macro-block of the reference picture data stored in said first memory means; correction means coupled to the first memory means and receiving picture data therefrom for correcting the picture data by post-filtering for phase deviation between top and bottom fields, with phases of respective pixels of the top field in a vertical direction being (1+2N)/2, where N is a positive even integer including zero and phases of respective pixels of the bottom field in the vertical direction being M, where M is a positive odd integer, so that the corrected phrase of the pixels of the top field in the vertical direction are P, where P is a positive even integer including zero, and so that the corrected phases of the pixels of the bottom field in the vertical direction are Q, where Q is a positive odd integer; said correction means being additionally coupled to the first addition means for converting a picture frame of the first resolution into a picture frame of the second resolution; said first inverse orthogonal transform means inverse orthogonal transforming coefficients of low-frequency components of said orthogonal transform block; said second inverse orthogonal transform means including a first picture decoding unit for inverse orthogonal transforming coefficients of the entire frequency components of said orthogonal transform block, separating respective pixels of the inverse orthogonal transformed orthogonal transform block into two pixel blocks associated with interlaced scanning, orthogonal transforming the separated two pixel blocks, inverse orthogonal transforming the coefficients of the low-frequency components of the two orthogonal transformed pixel blocks and synthesizing the inverse orthogonal transformed two pixel blocks to generate an orthogonal transform block; third inverse orthogonal transform means for inverse orthogonal transforming the orthogonal transform block of compressed picture data, orthogonal transformed in the frame orthogonal transform mode; second addition means for summing the compressed picture data, inverse orthogonal transformed by said third inverse orthogonal transform means, to motion compensated reference picture data, to output moving picture data of the second resolution; second memory means for storing the moving picture data outputted by said second addition means as reference picture data; and second motion compensation means for motion compensating the macro-block of reference picture data stored in said second memory means; said first inverse orthogonal transform means including a second picture decoding unit for inverse orthogonal transforming coefficients of low-frequency components of said orthogonal transform block; conversion means couple to the second memory means and receiving picture data therefrom for converting a picture frame of the first resolution into a picture frame of the second resolution; wherein if compressed picture data of the first resolution, encoded from the moving picture signals of the interlaced scanning system, are inputted, the moving picture data of the second resolution are decoded by said first picture decoding unit; and if compressed picture data of the first resolution, encoded from the moving picture signals of the sequential scanning system, are inputted, the moving picture data of the second resolution are decoded by said second picture decoding unit, whereby with said picture decoding apparatus for decoding compressed picture data of a first resolution, moving picture data of a second resolution lower than the first resolution is obtained regardless of whether the first or the second decoding unit is used.