Methods and systems for picture up-sampling

• US 8,670,489 B2
• Filed: 05/01/2012
• Issued: 03/11/2014
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sun, Shijun
• Primary Examiner(s): LEE, Y YOUNG
• Application Number:
  US13/461,538
• Publication Number:
  US 20120213296A1
• Time in Patent Office: 679 Days
• Field of Search: 375/240.01, 375/240.29
• US Class Current: 375/240.29
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/198 including smoothing of a sequence of encoding parameters, e.g. by averaging, by choice of the maximum, minimum or median value
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop

Abstract

Aspects of the present invention relate to systems and methods for picture up-sampling using direct interpolation. Some aspects of the present invention provide an up-sampling procedure designed for the Scalable Video Coding extension of H.264/MPEG-4 AVC.

Claims

1. A method for picture up-sampling from a base-layer picture comprising base-layer image samples, base_L[•

, •

], to an enhancement-layer picture comprising enhancement-layer image samples, pred_L[•

, •

], comprising;

defining a position, (xP, yP), for an upper-left sample of a block of said enhancement-layer picture;

deriving a relative location, xB, yB, xB1, yB1, of said block of said enhancement-layer picture in said base-layer picture; and

producing a sample block array, pred_L[x, y], wherein said producing comprises;

forming a temporary sample array, temp_L[x, y];

deriving an entry in said temporary sample array, wherein said deriving comprises;

calculating a corresponding fractional-sample y-position, yf, in said base-layer picture;

calculating a y-position interpolation center, yInt, based on yf;

calculating a y-position phase based on yf;

obtaining a first set of filter coefficients for a first six-tap filter, wherein said obtaining of said first set of filter coefficients is based on said y-position phase; and

deriving said entry temp_L[x, y] according to;

temp_L[x, y]=base_L[x, yInt−

2]*e[−

2]+base_L[x, yInt−

1]*e[−

1]+base_L[x, yInt]*e[0]+base_L[x, yInt+1]*e[1]+base_L[x, yInt+2]*e[2]+base_L[x, yInt+3]*e[3],

wherein e[−

2], e[−

1], e[0], e[1], e[2], and e[3] represent said first set of filter coefficients for said first six-tap filter; and

deriving an entry in said sample block array, pred_L[x, y], wherein said deriving comprises;

calculating a corresponding fractional-sample x-position, xf, in said base-layer picture;

calculating an x-position interpolation center, xInt, based on xf;

forming an x-position phase based on xf;

obtaining a second set of filter coefficients for a second six-tap filter, wherein said obtaining of said second set of filter coefficients is based on said x-position phase; and

deriving said entry pred_L[x, y] according to;

pred_L[x, y]=Clip1_y(( temp_L[xInt−

2, y]*e[−

2]+temp_L[xInt−

1, y]*e[−

1]+temp_L[x, yInt]*e[0]+temp_L[xInt+1, y]*e[1]+temp_L[xInt+2, y]*e[2]+temp_L[xInt+3, y]*e[3]+512)/1024),

wherein e[−

2], e[−

1], e[0], e[1], e[2], and e[3] represent said second set of filter coefficients for said second six-tap filter.

2. The method of claim 1 further comprising defining an interpolation resolution.

3. The method of claim 2, wherein said interpolation resolution is 1/16 (one-sixteenth) of an image sample.

4. The method of claim 1, wherein said base-layer image samples comprise luminance samples.

5. The method of claim 1, wherein said base-layer image samples comprise chrominance samples.

6. The method of claim 1, wherein said obtaining of said first set of filter coefficients comprises accessing a look-up-table.

7. The method of claim 6, wherein said look-up-table comprises samples of a Lanczos-windowed sinc function.

8. The method of claim 1, wherein said obtaining of said second set of filter coefficients comprises accessing a look-up-table.

9. The method of claim 8, wherein said look-up-table comprises samples of a Lanczos-windowed sinc function.

10. The method of claim 1, wherein said block is a macroblock of dimension 16 by 16.

11. The method of claim 1, wherein said block has the same spatial dimensions as said enhancement-layer picture.