结合HSV与纹理特征的视频阴影消除算法
Video shadow elimination algorithm by combining HSV with texture features
- 2017年22卷第10期 页码:1373-1380
网络出版:2017-09-23,
纸质出版:2017
DOI: 10.11834/jig.170151
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网络出版:2017-09-23,
纸质出版:2017
移动端阅览
在视频监控目标检测应用中,场景中的阴影会直接影响目标检测的准确度,因此阴影抑制算法研究显得尤为重要。目前广泛使用的是HSV(hue,saturation,value)阴影抑制方法,但是该方法存在由于亮度比值的阈值不稳定而造成将运动目标也检测为阴影的问题。针对该问题,本文提出了一种结合HSV与纹理特征的视频阴影消除方法。 首先将输入的图像使用传统的混合高斯模型建立背景并在灰度空间中提取前景,其次在HSV空间使用亮度比的阈值方法检测阴影,二者综合得到运动目标;针对由于亮度比值的阈值不稳定而导致的前景误检为阴影的问题,采用了LBP(local binary pattern)算子结合大津阈值(OTSU)提取部分运动目标。最后将LBP算子结合大津阈值提取的部分运动目标与HSV空间检测的目标两者相或,最终去除运动目标的阴影。 本文选用在CVPR-ATON和CAVIAR标准视频库中多个场景的阴影视频,将本文算法与SNP算法、SP算法、DNM1算法和DNM2算法进行对比仿真,实验结果表明本文算法在阴影检测率和阴影识别率的平均值上提升约10%。 本文提出的视频阴影消除算法结合了HSV与纹理特征,可以在不同的环境中有效地去除阴影,运动目标保留完整,可适用于智能视频监控、遥感图像和人机交互中。
In the application of video surveillance target detection
the shadow will directly affect the accuracy of the target detection in the scenes
so the shadow suppression algorithm is particularly important.The traditional algorithm which is based on hue
saturation
and value(HSV) to detect shadow is popular.Inspired by color perception mechanism of human visual system
this algorithm detects the shadow by the luminance ratio between the current video frame and background model.We propose a shadow elimination algorithm based on HSV spatial feature and texture features to overcome the shortcoming of the luminance ratio between them
which causes the moving target to be mistaken for the shadow. The Gaussian mixture model can effectively overcome the interference caused by the change of illumination and periodic disturbance of background image.First
the mixed Gaussian model(essentially 3 to 5) is used to characterize each pixel in the input images
and the updating mixed Gaussian model is obtained after the new input frame image.Each pixel of the current image is matched with the mixed Gaussian model
and if it is successful
the point belongs to background;otherwise
it belongs to foreground.The algorithm based on HSV color space can detect the shadow accurately by calculating the luminance ratio between the current video frame and the background model because the hue and saturation values are approximate in the shadow compared with the ones in the background
and the luminance value of shadow pixels is lower than the luminance value of the background pixels.The luminance ratio between them is usually 0.7 to 1.Therefore
the moving target can be obtained by combining the foreground detected by Gaussian mixture background model with the shadow detected by the method based on HSV color space.The traditional algorithms based on HSV color space can obtain the accurate detection results
but the moving target is often mistaken for shadows seriously in the video frames.To overcome this problem
we use texture featuresthat conclude local binary pattern(LBP) and OTSU to extract the moving target.LBP is an operator of gray-scale variation.A smaller threshold is selected
which is compared with the difference value between gray value of the central pixel and gray value of its corresponding neighborhood pixel.If the difference is greater than the threshold
it is marked as 1;otherwise
it is marked as 0.Therefore
we can obtain a description of the texture change at the location of the central pixel.The LBP operator extracts local texture features by the original gray level of the image.OSTU is a maximum interclass variance method.If the shadow and the target have large variances
then the two parts have much difference.When the partial target is regarded as shadows or part of the shadow is regarded as the target
the difference of two parts becomes smaller.Thus
the largest variance segmentation between classes can result in a minimum probability of misclassification.According to the gray feature of image
the image is divided into the shadow and the target by OTSU.The complete moving target is obtained by OR operator of combining the foreground
which is respectivelyextracted by OTSU and LBP operator with the result that is extracted by HSV. The proposed algorithm is applied to several different shadow videos
which are included in CVPR-ATON standard video library and CAVIAR standard video library.Experimental results show that when the threshold of luminance ratio
which is applied to detect the shadow in HSV color space
remains unchanged
the moving target is extracted accurately and its shadows are basically eliminated.Compared with other traditional algorithms
such as statistical parametric(SP) approach
statistical nonparametric(SNP) approach
and two kinds of deterministic non-model(DNM1
DNM2) approach
the proposed algorithm obtain the better result.Experimental results show that the proposed algorithm has much better increment of about 10% than the forehead algorithms in terms of the average of shadow detection rate and shadow discrimination rate.Although in the Intelligent Room video
the shadow discrimination rate is 1.6% lower than that of the DNM2 algorithm and the shadow discrimination rate is 2.9% lower than that of the SP algorithm in the video of Laboratory;thus
the algorithm improves the shadow detection rate by 29% and 27.2%
respectively.In the real-time test
this algorithm can process 12~15 frames per second
which can satisfy the real-time needs. Although the traditional algorithms that use HSV has great effect in the shadow elimination
the moving target may easily be interpreted as the shadow.The texture featuresthat include LBP and OTSU can make up for this shortcoming
wepropose the video shadow elimination algorithm by combining HSV with Texture features.Compared with other algorithms
our method can obtain more accurate shadow detection result and has much better advantages in terms of average shadow detection rate and shadow discrimination.Our method can be applied to intelligent video surveillance
remote sensing images
and human-computer interaction.Our future work will focus on improving the real-time performance.
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