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Partial characteristic description method

A technology of local features and local blocks, applied in image data processing, instrumentation, calculation, etc., to achieve excellent decorrelation, facilitate transmission and storage, and simple calculation

Active Publication Date: 2012-12-26
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Most of these existing methods increase the matching speed at the expense of matching quality

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Embodiment Construction

[0022] Such as Figure 1-4 As shown, the present invention includes several steps of preprocessing, polar grid sampling, mapping, DCT calculation, zigzag scanning and descriptor formation. Details are as follows.

[0023] Step 1. Preprocessing: feature detection and normalization.

[0024] Step 1: Use a feature detector to detect the local feature region of the image and map it to a local block of size d×d (d=41). Local feature region detection uses Hessian affine detector.

[0025] Step 2: Use Gaussian filtering to remove interpolation noise caused by affine normalization. Gaussian filtering uses a Gaussian kernel with a size of 5×5 and a standard deviation of 1.

[0026] Step 3: Use the mean μ and standard deviation σ of the local block gray value obtained in step 2 to normalize each pixel x of the block again i , remove the influence of illumination changes to get the normalized local block gray value y i , get as figure 1 The preprocessed local blocks are shown. the...

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Abstract

The invention provides a partial characteristic description method. The method comprises the steps of firstly normalizing obtained partial interest areas, subsequently dividing partial blocks by using polar coordinate sampling grids, carrying out quantization sampling on the partial blocks, mapping the partial blocks into a two-dimensional matrix and extracting two-dimensional DCT (Discrete Cosine Transform) frequency domain characteristics, furthermore scanning a DCT coefficient matrix in a zigzag sequence, and reordering and screening the DCT characteristics so as to form final partial descriptors. With the adoption of a polar coordinate sampling structure, not only is the original space information of the partial blocks kept, but also certain deformation can be tolerated, and the robustness of the descriptors is enhanced. The calculation on two-dimensional DCT characteristics is simple and efficient with compactness; and the illumination influence is further removed from the screened DCT characteristics.

Description

technical field [0001] The invention designs a digital image processing technology, and particularly relates to a local feature processing technology of an image. Background technique [0002] Compared with the global features, the local features of the image can obtain reliable matching when the object is deformed or occluded, so it has attracted much attention in the fields of image processing and computer vision. Local features have been widely used in wide-baseline matching, object recognition, texture classification, image retrieval and other fields. [0003] In general, local features involve three steps: local feature detection, local feature description, and local feature matching. First use the feature detector to detect the interest point (or interest area) of the image, then calculate the image descriptor on the surrounding support area of ​​the located interest point, and finally use the appropriate matching function to measure the distance between the descripto...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/00
Inventor 李宏亮宋铁成
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA