Picture decoding method and apparatus

• US 20020041632A1
• Filed: 12/13/2000
• Published: 04/11/2002
• Est. Priority Date: 12/16/1999
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kumar Dixit, Rajesh, Sugawara, Hiroshi, Sato, Kazushi, Goseki, Masami, Terao, Takao
• Granted Patent: US 6,839,386 B2
• Time in Patent Office: Days
• US Class Current: 375/240.25
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/112 according to a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence

Abstract

It is targeted to prevent picture quality deterioration in the output picture information proper to the interlaced scanned picture and that ascribable to interlaced scanning. To this end, a decimating inverse discrete cosine transform unit 5 applies inverse orthogonal transform to four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction among the respective coefficients of an orthogonal transform block of the compressed picture information of the input high resolution picture.

Claims

1. A picture decoding apparatus for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

inverse orthogonal transform means for inverse orthogonal transforming each coefficient of the orthogonal transform block of the orthogonal transformed compressed picture information;

addition means for summing the transformed picture information obtained on inverse orthogonal transform by said inverse orthogonal transform means to the motion compensated reference picture information to output said moving picture information of the second resolution;

storage means for memorizing the moving picture information output by said addition means as the reference picture information;

first motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction mode); and

second motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode);

said inverse orthogonal transform means inverse orthogonal transforming four coefficients in the low range in the horizontal direction and eight coefficients in the vertical direction in respective coefficients in an orthogonal transform block of the compressed picture information.

2. The picture decoding apparatus according to claim 1 further comprising:

signal separating means for separating the compressed picture information of said first resolution into the compressed picture information pertinent to luminance signals and into the compressed picture information pertinent to chroma signals;

said inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in the coefficients of the orthogonal transform of the compressed picture information pertinent to luminance signals separated by said signal separating means;

said addition means summing the picture information of the luminance signals inverse orthogonal transformed by said inverse orthogonal transform means to the motion compensated reference picture information to output the moving picture information of said second resolution.

3. A picture decoding apparatus for decoding the moving picture information of a second resolution from the compressed picture information- of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

signal separating means for separating the compressed picture information of the first resolution into the compressed picture information pertinent to luminance signals and into the compressed picture information pertinent to chroma signals;

first inverse orthogonal transform means for inverse orthogonal transforming respective coefficients of the orthogonal transform block of the compressed picture information pertinent to orthogonal transformed and separated luminance signals;

first addition means for summing the first picture information pertinent to luminance signals inverse orthogonal transformed by said first inverse orthogonal transform means to the motion compensated first reference picture information to output said moving picture information;

first storage means for memorizing the moving picture information output by said first addition means as the reference picture information;

first motion compensation means for motion compensating the macroblock of the reference picture information, motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field prediction mode);

second motion compensation means for motion compensating the macroblock of the reference picture information, motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame prediction mode);

second inverse orthogonal transform means for inverse orthogonal transforming an orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transform in accordance with the orthogonal transform system associated with the interlaced scanning (field orthogonal transform mode) and subsequently separated by said signal separating means;

third inverse orthogonal transform means for inverse orthogonal transforming an orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transform in accordance with the orthogonal transform system associated with the sequential scanning (frame orthogonal transform mode) and subsequently separated by said signal separating means;

second addition means for summing the compressed picture information pertinent to chroma signals inverse orthogonal transformed by said second inverse orthogonal transform means or said third inverse orthogonal transform means to the motion compensated second reference picture information to output said moving picture information;

second storage means for memorizing the moving picture information output by said second addition means as the reference picture information;

third motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system (field motion prediction mode) associated with the interlaced scanning; and

fourth motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system (frame motion prediction mode) associated with the sequential scanning;

said first inverse orthogonal transform means inverse orthogonal transforming four low range coefficients in the horizontal direction and eight coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to luminance signals separated by said signal separating means;

said second orthogonal transform means inverse orthogonal transforming four low range coefficients in the horizontal direction and four low range coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning and subsequently separated by said signal separating means;

said third orthogonal transform means inverse orthogonal transforming inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals separated by said signal separating means following orthogonal transform in accordance with the orthogonal transform system associated with said sequential scanning, separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, and synthesizing the top and bottom fields obtained on inverse orthogonal transform.

4. The picture decoding apparatus according to claim 3 wherein said second inverse orthogonal transform means inverse orthogonal transforms four low range coefficients in the horizontal direction and four low range coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning and subsequently separated by said signal separating means;

said third orthogonal transform means inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated by said signal separating means, said third orthogonal transform means separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, phase-correcting the respective pixels of the top field obtained on inverse orthogonal transform, in the vertical direction, phase-correcting the respective pixels of the bottom field obtained on inverse orthogonal transform, in the vertical direction, and synthesizing the phase-corrected top and bottom fields.

5. A picture decoding apparatus for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

picture type separating means for analyzing the picture type of the compressed picture information of the first resolution and for separating the compressed picture information of the first resolution into the compressed picture information pertinent to the I- and P-pictures and into the compressed picture information pertinent to B- pictures;

first orthogonal transform means for inverse orthogonal transforming respective coefficients of the orthogonal transform block of the I- and P-pictures orthogonal transformed and separated by said picture type separating means;

first addition means for summing the compressed picture information pertinent to the I- and P-pictures inverse orthogonal transformed by said first inverse orthogonal transform means to the motion compensated first reference picture information to output said moving picture information;

first storage means for memorizing the moving picture information output by said first addition means as the reference picture information;

first motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning(field motion prediction mode);

second motion compensation means for motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode);

second inverse orthogonal transform means for inverse orthogonal transforming the orthogonal transform block of the compressed picture information pertinent to said B-pictures orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning (field orthogonal transform mode) and separated by said picture separating means;

third inverse orthogonal transform means for inverse orthogonal transforming the orthogonal transform block of the compressed picture information pertinent to said B-pictures orthogonal transformed in accordance with the orthogonal transform system associated with the sequential scanning (frame orthogonal transform mode) and separated by said picture separating means;

second addition means for summing the compressed picture information pertinent to B-pictures inverse orthogonal transformed by said second or third inverse orthogonal transform means to the motion compensated second reference picture information;

second storage means for memorizing the moving picture information output by said second addition means as the reference picture information;

third motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted by the motion prediction system associated with the interlaced scanning (field motion prediction mode); and

fourth motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted by the motion prediction system associated with the sequential scanning (frame motion prediction mode);

said first inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to I and P-pictures separated by said picture type separating means;

said second inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal and vertical directions in the respective coefficients of the orthogonal transform block of the compressed picture information of the B-pictures orthogonal transformed in accordance with the orthogonal transform system associated with said interlaced scanning and subsequently separated by said picture type separating means;

said third orthogonal transform means inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transform in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated by said signal separating means, said third orthogonal transform means separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, and synthesizing the top and bottom fields obtained on orthogonal transform.

6. The picture decoding apparatus according to claim 5 wherein said second inverse orthogonal transform means applies inverse orthogonal transform to four low-range coefficients in the horizontal and vertical directions, in respective coefficients of the orthogonal transform blocks of the compressed picture information pertinent to the I- and P-pictures orthogonal transform in accordance with the orthogonal transform system associated with said interlaced scanning and subsequently separated by said picture type separating means;

said third orthogonal transform means inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform blocks of the compressed picture information pertinent to B-pictures orthogonal transformed in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated by said signal separating means, said third orthogonal transform means separating the orthogonal transform block resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, phase-correcting the respective pixels of the top field obtained on inverse orthogonal transform, in the vertical direction, phase-correcting the respective pixels of the bottom field obtained on inverse orthogonal transform, in the vertical direction, and synthesizing the phase-corrected top and bottom fields.

7. A picture decoding apparatus for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

picture type separating means for analyzing the picture type of the compressed picture information of the first resolution and for separating the compressed picture information of the first resolution into the compressed picture information pertinent to the I- and P-pictures and into the compressed picture information pertinent to B- pictures;

signal separating means for separating the compressed picture information of the first resolution into the compressed picture information pertinent to luminance signals and into the compressed picture information pertinent to chroma signals;

first inverse orthogonal transform means for applying first inverse orthogonal transform to respective coefficients of the orthogonal transform block of the compressed picture information pertinent to luminance signals of said I- and P-pictures orthogonal transformed and separated by said picture type separating means and said signal separating means;

first addition means for summing the compressed picture information pertinent to luminance signals of I- and P-pictures orthogonal transformed by said first orthogonal transform means to output said moving picture information;

first storage means for memorizing said moving picture information output by said first addition means as the reference picture information;

first motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction mode);

second motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode);

second inverse orthogonal transform means for inverse orthogonal transforming orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P-pictures and to B-pictures obtained on orthogonal transform in accordance with the orthogonal transform system associated with the interlaced scanning (field orthogonal transform mode) and subsequent separation by said picture type separating means and said signal separating means;

third inverse orthogonal transform means for inverse orthogonal transforming the orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P-pictures and to B pictures obtained on orthogonal transform in accordance with the orthogonal transform system associated with the sequential scanning (frame orthogonal transform mode) and subsequent separation by said picture type separating means and said signal separating means;

second addition means for summing the compressed picture information pertinent to chroma signals of I- and P-pictures and to B-pictures obtained on orthogonal transform by said second or third inverse orthogonal transform means, to output the moving picture information;

second storage means for memorizing the moving picture information output by the second addition means as reference picture information;

third motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction mode);

fourth motion compensation means for motion compensating a macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode);

said first inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction in the coefficients of the orthogonal transform blocks of the compressed picture information pertinent to luminance signals of said I- and P- pictures;

said second inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal direction and four low-range coefficients in the vertical direction in the coefficients of the orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P-pictures and B-pictures separated by said picture type separating means and said signal separating means;

said third inverse orthogonal transform means inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P- pictures and to B-pictures separated by said picture type separating means and signal separating means, said third orthogonal transform means separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, and synthesizing the top and bottom fields obtained on inverse orthogonal transform.

8. The picture decoding apparatus according to claim 7 wherein said second inverse orthogonal transform means inverse orthogonal transforms four low-range coefficients in the horizontal and vertical directions in the respective coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals of I- and P-pictures and B-pictures as separated by said picture type separating means and signal separating means, said second inverse orthogonal transform means also phase- correcting the respective pixels obtained on inverse orthogonal transform in the vertical direction;

said third inverse orthogonal transform means inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P- pictures and to B-pictures separated by said picture type separating means and signal separating means, said third orthogonal transform means separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, phase- correcting respective pixels of the top field obtained on inverse orthogonal transform, in the vertical direction, phase-correcting respective pixels of the bottom field obtained on inverse orthogonal transform, in the vertical direction, and synthesizing the phase-corrected top and bottom fields.

9. A picture decoding apparatus for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

inverse orthogonal transform means for inverse orthogonal transforming respective coefficients of orthogonal transform blocks of the orthogonal transformed compressed picture information;

addition means for summing the transformed picture information, inverse orthogonal transformed by said inverse orthogonal transform means, to the motion compensated reference picture information, to output the moving picture information of said second resolution;

picture type separating means for analyzing the picture type of the compressed picture information of the first resolution and for separating the compressed picture information of the first resolution into the compressed picture information pertinent to the I- and P-pictures and into the compressed picture information pertinent to B- pictures;

thinning means for thinning out the moving picture information pertinent to B- pictures furnished from said picture type separating means in the vertical direction storage means for memorizing the moving picture information pertinent to I- and P-pictures furnished from said picture type separating means and the moving picture information pertinent to the thinned B-pictures furnished from said thinning means, as the reference picture information;

first motion compensation means for motion compensating a macroblock of the reference picture information, motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction mode);

second motion compensation means for motion compensating a macroblock of the reference picture information, motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode);

said inverse orthogonal transform means inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction in respective coefficients of the orthogonal transform block of said compressed picture information.

10. The picture decoding apparatus according to claim 9 wherein said thinning means thins out the moving picture information pertinent to the B-pictures furnished from said picture type separating means in the vertical direction.

11. A picture decoding method for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in coefficients of orthogonal transform blocks of the orthogonal transformed compressed picture information;

summing the inverse orthogonal transformed picture information to the motion compensated reference picture information to output the moving picture information of the second resolution;

memorizing the output moving picture information as the reference picture information;

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with interlaced scanning (field motion prediction system); and

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with sequential scanning (frame motion prediction system).

12. The picture decoding method according to claim 11 further comprising:

separating the compressed picture information of the first resolution into the compressed picture information pertinent to luminance signals and compressed picture information pertinent to chroma signals;

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in the respective coefficients of the orthogonal transform block of the compressed picture information pertinent to the separated luminance signal; and

summing the inverse transformed picture information pertinent to the inverse orthogonal transformed luminance signals to output the moving picture information of the second resolution.

14. The picture decoding method according to claim 13 further comprising:

inverse orthogonal transforming four low range coefficients in the horizontal direction and four low range coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning and subsequently separated;

inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated;

separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, phase-correcting the respective pixels of the top field obtained on inverse orthogonal transform, in the vertical direction phase-correcting the respective pixels of the bottom field obtained on inverse orthogonal transform, in the vertical direction, and synthesizing the phase-corrected top and bottom fields.

16. The picture decoding method according to claim 15, further comprising:

inverse orthogonal transforming low-range low coefficients in the horizontal and vertical directions, in the respective coefficients of an orthogonal transform block of the compressed picture information pertinent to I- and P-pictures orthogonal transformed in the orthogonal transform system associated with the interlaced scanning, and subsequently separated, phase-correcting the respective pixels obtained on this orthogonal transform in the vertical direction, inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to B-pictures orthogonal transformed in the orthogonal transform system associated with the sequential scanning and subsequently separated, separating the orthogonal transform block resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of the low frequency components of the orthogonal transformed two pixel blocks, phase- correcting the pixels of the top field obtained on inverse orthogonal transform in the vertical direction, phase-correcting the pixels of the bottom field obtained on inverse orthogonal transform in the vertical direction and synthesizing the phase-corrected top and bottom fields.

18. The picture decoding method according to claim 17 further comprising:

inverse orthogonal transforming four low-range coefficients in the horizontal and vertical direction in the coefficients of the orthogonal transform block of the compressed picture information pertinent to the chroma signals of the I- and P-signals and said B-pictures, separated from each other, with the respective pixels obtained on inverse orthogonal transforming being corrected in phase;

inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform blocks of the compressed picture information pertinent to chroma signals of said I- and P-pictures and to B-pictures, separated from each other, separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, phase-correcting respective pixels of the top field obtained on inverse orthogonal transform, in the vertical direction, phase- correcting respective pixels of the bottom field obtained on inverse orthogonal transform, in the vertical direction, phase-correcting respective pixels of the top field, obtained on inverse orthogonal transform, in the vertical direction, phase-correcting respective pixels of the bottom field, obtained on inverse orthogonal transform, in the vertical direction, and synthesizing the phase-corrected top and bottom fields.

20. The picture decoding method according to claim 19 further comprising:

thinning out the moving picture information pertinent to the separated B- pictures by ½

in the vertical direction .

13. A picture decoding method for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

separating the compressed picture information of said first resolution into the compressed picture information pertinent to luminance signals and into the compressed picture information pertinent to chroma signals;

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in respective coefficients of the orthogonal transform blocks of the compressed picture information pertinent to the orthogonal transformed and separated luminance signals;

summing the first transformed picture information pertinent to said inverse orthogonal transformed luminance signals to the motion compensated first reference picture information to output said moving picture information;

memorizing the output moving picture information as the reference picture information;

motion compensating a macroblock of the reference picture information motion- predicted in accordance with a motion prediction system associated with interlaced scanning (field motion prediction mode);

motion compensating a macroblock of the reference picture information motion- predicted in accordance with a motion prediction system associated with sequential scanning (frame motion prediction mode);

inverse orthogonal transforming four low range coefficients in the horizontal direction and four low range coefficients in the vertical direction, in respective coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning and subsequently separated;

inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transformed in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated, separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, and synthesizing the top and bottom fields obtained on inverse orthogonal transform;

summing the compressed picture information pertinent to the inverse orthogonal transformed chroma signals and the motion compensated second reference picture information to output said moving picture information;

memorizing the output moving picture information as the reference picture information,

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with interlaced scanning (field motion prediction system); and

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with sequential scanning (frame motion prediction system).

15. A picture decoding method for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

analyzing the picture type of the compressed picture information of the first resolution and separating the compressed picture information of the first resolution into the compressed picture information pertinent to I- and P-pictures and into the compressed picture information pertinent to B-pictures;

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in the respective coefficients of the orthogonal transform block of the compressed picture information pertinent to orthogonal transformed and separated I- and P-pictures;

summing the compressed picture information pertinent to the I- and P-pictures to the motion compensated first reference picture information to output said moving picture information;

memorizing the output moving picture information as the reference picture information;

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction system);

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction system);

inverse orthogonal transforming four low range coefficients in the horizontal direction and four low range coefficients in the vertical direction, in the respective coefficients of the orthogonal transform block of the compressed picture information pertinent to B-pictures orthogonal transform in accordance with the orthogonal transform system associated with the interlaced scanning and subsequently separated;

inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to chroma signals orthogonal transform in accordance with the orthogonal transform system associated with said sequential scanning and subsequently separated, separating orthogonal transform blocks resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of low frequency components in the respective coefficients of the two orthogonal transformed pixel blocks, and synthesizing the top and bottom fields obtained on inverse orthogonal transform;

summing the compressed picture information pertinent to the inverse orthogonal transformed B-pictures and the motion compensated second reference picture information to output said moving picture information;

memorizing the output moving picture information as the reference picture information, motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with interlaced scanning (field motion prediction system); and

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with sequential scanning (frame motion prediction system).

17. A picture decoding method for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

analyzing the picture type of the compressed picture information of the first resolution and separating the compressed picture information of the first resolution into the compressed picture information pertinent to I- and P-pictures and into the compressed picture information pertinent to B-pictures;

separating the compressed picture information of the first resolution into the compressed picture information pertinent to luminance signals and into the compressed picture information pertinent to chroma signals;

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in the respective coefficients of the orthogonal transform block of the compressed picture information pertinent to luminance signals of the orthogonal transformed and separated I- and P-pictures;

summing the compressed picture information pertinent to luminance signals of the inverse orthogonal transformed I- and P-pictures to the motion compensated first reference picture information to output said moving picture information;

memorizing said output moving picture information as the reference picture information;

motion compensating a macroblock of the reference picture information motion- predicted in accordance with the motion prediction system associated with interlaced scanning (field motion prediction mode);

motion compensating a macroblock of the reference picture information motion- predicted in accordance with the motion prediction system associated with sequential scanning (frame motion prediction mode);

inverse orthogonal transforming four low-range horizontal and vertical directions in the coefficients of the orthogonal transform block of the compressed picture information pertinent to chroma signals of I- and P-signals and B-pictures orthogonal transformed in accordance with the orthogonal transform system associated with the interlaced scanning (field orthogonal transform mode) and subsequently separated;

inverse orthogonal transforming coefficients of the totality of frequency components of the orthogonal transform block of the compressed picture information pertinent to B-pictures and chroma signals of the I- and P-pictures orthogonal transformed in the orthogonal transform system associated with the sequential scanning (frame orthogonal transform mode), and subsequently separated, separating the orthogonal transform block resulting from the inverse orthogonal transform into two pixel blocks associated with interlaced scanning, orthogonal transforming the two separated pixel blocks, inverse orthogonal transforming coefficients of the low frequency components of the orthogonal transformed two pixel blocks, and synthesizing the inverse orthogonal transformed top and bottom fields;

summing the compressed picture information pertinent to chroma signals of the inverse orthogonal transformed I- and P-pictures and B-pictures to output the moving picture information;

memorizing the output moving picture information as the reference picture information;

motion compensating a macroblock of the reference picture information motion- predicted in accordance with the motion prediction system associated with interlaced scanning (field motion prediction mode); and

motion compensating a macroblock of the reference picture information motion- predicted in accordance with the motion prediction system associated with sequential scanning (frame motion prediction mode).

19. A picture decoding method for decoding the moving picture information of a second resolution from the compressed picture information of a first resolution obtained on predictive encoding in terms of a pre-set pixel block (macroblock) as a unit and on orthogonal transform in terms of a pre-set pixel block (orthogonal transform block) as a unit, said second resolution being lower than said first resolution, said picture decoding apparatus comprising:

inverse orthogonal transforming four low-range coefficients in the horizontal direction and eight coefficients in the vertical direction, in respective coefficients of an orthogonal transform block of the orthogonal transformed compressed picture information;

summing the inverse orthogonal transformed picture information to the motion compensated reference picture information to output the moving picture information of said second resolution;

analyzing the picture type of the compressed picture information of said first resolution to separate the compressed picture information pertinent into the compressed picture information pertinent to I- and P-pictures and into the compressed picture information pertinent to B-pictures;

thinning out the separated moving picture information pertinent to the B- pictures in the vertical direction;

memorizing the moving picture information pertinent to the I- and P-pictures and the thinned moving picture information pertinent to B-pictures, separated from each other, as the reference picture information;

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the interlaced scanning (field motion prediction mode); and

motion compensating the macroblock of the reference picture information motion-predicted in accordance with the motion prediction system associated with the sequential scanning (frame motion prediction mode).