Adaptive frequency domain filtering for phase plane correlation

Patent metadata

Field	Value
Publication number	US-9300966-B2
Application number	US-62192409-A
Country	US
Kind code	B2
Filing date	Nov 19, 2009
Priority date	Nov 20, 2008
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

In a Phase Plane Correlation (PPC) process, using adaptive frequency domain filtering to aid in generating candidate motion vectors. It is determined when it is beneficial to pre-filter an input image, prior to a PPC process. This results in more reliable and consistent PPC surfaces than otherwise. The filter is applied in the frequency domain where time-domain convolution becomes a much more efficient component-wise multiplication with an in-place window. An energy measure of the high-frequency content in the computed Fourier surfaces gauges the degree of high frequency content in the image. First, the Fourier transform of the two images is computed. Then, the high-frequency content is estimated from the Fourier surfaces. A window function is computed as a function of the high-frequency energy. The window is applied to the Fourier surfaces. Then, the modified Fourier surfaces are fed into the PPC process.

First claim

What is claimed is:

1. A method for producing a phase plane correlated surface comprising:
Fourier transforming by a digital device first and second time domain images to create a first and second phase plane images, respectively;
prefiltering the first and second phase plane images, said prefiltering based on certain predetermined criteria;
correlating by the digital device the first and second phase plane images to form a frequency domain correlated phase plane surface; and
inverse Fourier transforming the frequency domain correlated phase plane surface to provide a phase plane correlated surface.

2. The method according to claim 1 wherein the prefiltering leaves the first and second phase plane images unchanged.

3. The method according to claim 1 wherein the predetermined criteria relates to a frequency content of the first and second phase plane images.

4. The method according to claim 3 wherein the predetermined criteria relates to a frequency content of the first and second phase plane images in edge portions of those images.

5. The method according to claim 1 wherein the correlating includes fractional normalization.

6. The method according to claim 5 wherein the correlating that includes fractional normalization uses an exponent with a value in the range zero to one.

7. The method according to claim 5 wherein the correlating that includes fractional normalization uses an exponent value that is generated by a closed-form analytic equation or a look-up table.

Assignees

• Wredenhagen Gordon F
• Ati Technologies Ulc

Inventors

• Wredenhagen Gordon F

Classifications

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/117 Primary

  Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) · CPC title

• H04N19/80

  Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation (H04N19/635, H04N19/86 take precedence) · CPC title

• G06T2207/10016

  Video; Image sequence · CPC title

• G06T7/206

  Physics · mapped topic