Image matching device and method for motion pictures

• US 20080031339A1
• Filed: 09/28/2007
• Published: 02/07/2008
• Est. Priority Date: 08/02/2002
• Status: Active Grant

• Current Assignee: KDDI Corporation
• Original Assignee: KDDI Corporation
• Inventors: Wada, Masahiro, Kawada, Ryoichi, Koike, Atsushi, Sugimoto, Osamu
• Granted Patent: US 7,773,674 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10021 Stereoscopic video; Stereoscopic image sequence
• CPC Class Codes: G06T 7/223 using block-matching
• CPC Class Codes: H04N 5/145 Movement estimation for video coding H04N19/51
• CPC Class Codes: H04N 7/014 involving the use of motion vectors motion estimation and compensation in video coding H04N19/51

Abstract

A matching section performs motion estimation upon a predetermined processing unit of input video (p) by, e.g., an iterative gradient method. A motion vector (v) obtained by the iterative gradient method is obtained by the expression v=α·Δv+v₀ (wherein v₀ indicates an initial displacement motion vector and Δv indicates a differential vector). A characteristic amount extraction section extracts a characteristic amount from the distribution of motion vectors obtained by the motion estimation. A parameter determination section determines a conversion parameter α applied to the next processing unit by the characteristic amount. If the characteristic amount is equal to or larger than a predetermined threshold, the conversion parameter α is determined to be larger (e.g., α=1). If the characteristic amount is smaller than the threshold, the conversion parameter α is determined to be smaller (e.g., α=0.1).

Claims

1. An image matching method for performing an image matching by using an iterative gradient method which iteratively estimates at least one of motion or parallax of a video on a block-by-block basis based on an initial displacement vector, comprising the step of:

forming a plurality of small blocks by dividing the block into small blocks and applying the iterative gradient method to each of the small blocks to calculate the motion or parallax for every small block.

2. The image matching method according to claim 1, wherein motion vectors for neighbor blocks of the block are determined as motion vector candidates for the initial displacement vector of the small block and the initial displacement vector of the small block is selected from among the motion vector candidates.

3. The image matching method according to claim 2, wherein the motion vector candidates include motion vectors for a block in a previous frame corresponding to the block and for neighbor blocks thereof.

4. The image matching method according to claim 2, wherein the motion vector candidates include at least one of the motion vectors for the neighbor blocks of the block, a motion vector for a block in the previous frame corresponding to the block and a motion vector obtained by calculating motion vectors for neighbor blocks thereof.

5. An image matching device which performs an image matching by using an iterative gradient method for iteratively estimating at least one of motion and parallax of a video on a block-by-block basis based on an initial displacement vector, comprising:

an initial displacement vector determination section for determining the initial displacement vector for a small block obtained by dividing the block into a plurality of blocks; and

a second iterative gradient method performing means for calculating the motion vector of the small block based on the initial displacement vector determined in the initial displacement vector determination section.

6. The image matching device according to claim 5 further comprising a first iterative gradient method performing means for calculating the motion vector for the video block,

wherein the initial displacement vector determination section comprises:

a vector memory for storing a motion vector for at least one of blocks in the current and previous frames calculated by the first iterative gradient method performing means; and

an initial displacement vector selecting section for selecting the initial displacement vector of the small block from among motion vectors of neighbor blocks of the corresponding block read out from the vector memory.

7. The image matching device according to claim 6, wherein the initial displacement vector determination section further comprises a calculation section for calculating the motion vector read out from the vector memory to obtain the motion vector candidates, and at least one of motion vectors of neighbor blocks of the corresponding block read out from the vector memory and the motion vector as the result of calculation is determined as the motion vector candidates and thus the initial displacement vector of the small block is determined from among the motion vector candidates.