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Shadow detection and removal algorithm based on image segmentation

A technology of shadow detection and image segmentation, applied in the field of image processing

Inactive Publication Date: 2015-03-25
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

Today, shadow detection is still a very challenging problem due to factors such as lighting, object reflectivity, and shadow geometry.

Method used

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  • Shadow detection and removal algorithm based on image segmentation
  • Shadow detection and removal algorithm based on image segmentation
  • Shadow detection and removal algorithm based on image segmentation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0082] Example shadow edge detection

[0083] First, the shadow edge detector Pb is constructed by computing the directional gradient information G(x, y, θ). The method of construction is to draw a circle with a radius of r at a point (x, y) in the image, and the circle is divided into two semicircles by a diameter whose direction is θ. Finally by calculating the χ between the histograms of these two semicircles 2 The distance gets the directional gradient G:

[0084] χ 2 ( g , h ) = 1 2 Σ i ( g ( i ) - h ( i ) ) ...

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Abstract

The invention discloses a shadow detection and removal algorithm based on image segmentation, and relates to the technical field of image processing. The algorithm mainly solves the problems about how to judge whether shadows exist in a region or not or whether an edge is a shadow or not and how to remove corresponding shadows. The algorithm includes the steps that firstly, through texture and brightness characteristics, the probability that each pixel point is a shadow edge is estimated through the combination of local information and overall information; an image is segmented through a watershed algorithm and contour information shown in the specification; a shadow region and a non-shadow region in the image are segmented through a region fusion algorithm based on edges, and meanwhile the shadow region and the non-shadow region are segmented into multiple sub-regions respectively; then classifiers SVM are trained respectively for recognizing shadows; then, a shadow detection energy equation is solved through an image segmentation algorithm, and then a final shadow detection result is acquired; finally, according to the shadow detection result, shadow labels are calculated through an image matting algorithm, the shadow region is lightened through the marks, and illumination of the shadow region is restored.

Description

technical field [0001] The invention specifically relates to a shadow detection and removal algorithm based on image segmentation, which is used for image shadow detection and penumbra area removal, and belongs to the technical field of image processing. Background technique [0002] Shadow detection has always been one of the research hotspots in the field of image processing. Since the existence of shadows will increase the difficulty of algorithms such as object recognition and video segmentation, detecting and removing shadows can significantly improve the performance of many algorithms in the field of image processing. [0003] Many shadow detection methods are proposed based on illumination models or color models. Such as the shadow detection method under the color space HSI, this method uses the ratio of H and I in the HSI space to detect shadows. However, this method is more suitable for aerial images or images with obvious shadows, and the effect of shadow detecti...

Claims

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Application Information

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IPC IPC(8): G06T7/00
CPCG06T7/11G06T5/94
Inventor 刘颜丽陈卓
Owner SICHUAN UNIV
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