Abstract
In order to improve the recall and precision of image retrieval, a visual retrieval method of digital media image features based on active noise is proposed. In this paper, Canny algorithm is used to detect the edge of the image to get the feature information of the edge of the image. The RGB color space model is used to decompose the color information of the image, and the color characteristic information of the image is obtained. Extracting image features to retain the useful information contained in the image as much as possible; In order to facilitate the visual retrieval of image features, reduce the retrieval complexity and further fuse image features, FPCA and ReliefF algorithms are used to reduce the dimensionality of image features, and the active noise control method is used to sharpen the image. After processing the results, a digital media image feature visual retrieval platform is established to realize the visual retrieval of digital media image features. Experimental results show that the proposed method has a high accuracy of over 80% and a high recall rate of 95.2%.
Keywords
Introduction
With the rapid development of multimedia technology and network technology, digital media images have gradually become the main carrier of information, and have been widely and deeply applied in all walks of life, and various image databases have gradually formed [1]. Today, most digital media image resources are stored and transmitted in compressed form, and most of the compression coding standards are based on DCT. In order to better manage and use image databases, it is of great significance to study image retrieval techniques [2]. At this stage, the traditional image retrieval technology is carried out in the spatial domain, and the general steps can be divided into decoding compressed data, spatial feature extraction, and re-encoding to restore the compressed format [3]. There are two main problems in the implementation of traditional schemes. First, the codec process requires a lot of calculation; second, the whole process involves compression domain and spatial data, which requires a lot of data and occupies a lot of memory space [4, 5]. These two problems greatly reduce the recall rate and precision rate of image retrieval and fail to meet the requirements of modern people for image retrieval.
In view of the problems existing in the existing image retrieval technology, relevant scholars have improved the image retrieval technology. Wang et al. [6] proposed an image retrieval algorithm based on multi-feature fusion. In this method, a fusion formula FSF based on feature similarity was designed to extract global, main content and style features of clothing based on YOLOv3 model. Through training and metric learning training, CNN’s ability to extract clothing style attributes and features was improved. Then, the three-way CNN features were extracted and the FSF formula was used to calculate the multi-scale CNN fusion features. The Euclidean distance between optimized features is predicted, and semantic drift is suppressed. Finally, the deep semantic features extracted by CNN were supplemented, and traditional features were introduced to constrain texture, color and other features of initial retrieval results. Multi-scale CNN fusion features were combined with traditional features by FSF formula to optimize the ordering of initial retrieval results. The experimental results show that the algorithm can effectively optimize the image sorting results and improve the retrieval accuracy, but there is a problem of low precision in image retrieval. Shi et al. [7] proposed an image retrieval method based on joint weighted aggregation depth convolution feature. In this method, the image is input into the pre-trained convolutional neural network, and the last convolution output is extracted as the depth convolution feature of the image; by calculating the spatial weight matrix, the salient areas of the image are highlighted; according to the principle of maximum channel variance, the corresponding The feature map calculates the spatial weight matrix, and the original depthwise convolution features are weighted and aggregated into column vectors; the channel weight vector is calculated by treating the feature maps of different channels differently, and the final global feature vector is obtained. The experimental results on public data sets show that this method can effectively enhance the expression ability of image features, has obvious advantages in the average accuracy of image retrieval, and can be effectively applied to the related fields of image retrieval. However, this method has the problem of low recall and is easy to miss some images. Cui et al. [8] proposed a hash image retrieval method based on bilinear iterative quantization, which uses compact bilinear projection to map high-dimensional data into two smaller projection matrices; Then the iterative quantization method is used to minimize the quantization error and generate an effective hash code. Experiments on cifar-10 and caltech256 data sets show that this method can reduce the impact of high-dimensional data and can widely serve the hash image retrieval application of long coding bits of high-dimensional data. However, the retrieval results of this method are easy to include different images and the retrieval effect is poor.
To solve the above problems, a digital media image feature visual retrieval method based on active noise control is proposed to improve recall and precision of image retrieval and improve image retrieval effect. In this paper, Canny algorithm is firstly used to detect image edges to obtain image edge feature information, and then image features are extracted and fused. FPCA and ReliefF algorithms are used to reduce the dimension of image features, and active noise control method is used to sharpen the image. Finally, a digital media image feature visual retrieval platform is established to realize image visual retrieval. It is hoped that this paper can provide a good reference for modern image retrieval research.
Digital media image preprocessing
The digital media image feature visual retrieval method proposed in this paper draws lessons from the processing process of biological vision, and divides the image preprocessing into three steps: the first step is to detect the edge of the image; The second step decomposes the color information of the image to provide more features for the similarity comparison of the image; The third step is to measure the similarity of the processed image.
Image edge detection
Before image retrieval, first detect the edge of the image to obtain the image edge features, which is realized by Canny algorithm [9]. Canny algorithm uses Gaussian noise to describe the image edge, which is represented by a mathematical model of step change. The problem of edge detection is transformed into the problem of finding the maximum value of gradient function. The calculation process is divided into the following four steps:
Smooth the image with a Gaussian filter, which aims to remove the influence of noise on edge extraction [10]. The expression of the transfer function of the two-dimensional Gaussian filter is Calculate the gradient value and direction corresponding to each pixel by the finite difference of the first-order partial derivative. Non maximum suppression of gradient amplitude. For each critical point, search along the gradient direction and compare with the gradient values of all pixels in the gradient direction. If the gradient value of this pixel is the maximum value in the gradient direction, this pixel is considered as a boundary candidate point, otherwise it is regarded as a non boundary point. Eliminate false boundary points and connecting edges with a double-threshold algorithm. Given two critical values
According to the above steps, the edge detection result of digital media is obtained and the image edge feature information is obtained.
In addition to image edge information, image color information is also a relatively important image detail information. At present, most images are stored in digital image format, and the expression of color information in digital images is realized in the form of color space. The color space is divided into different models, such as RGB model, HSV model, HIS model, CMY model, Lab model, etc. [11]. In this paper, the RGB color space model is mainly used to decompose the color information of the image.
The RGB color space model utilizes the configuration of red, green, and blue color channels, which can express both color image information and grayscale image information. When expressing grayscale image information, the values of the red channel, green channel, and blue channel are equal. Therefore, the RGB representation of grayscale images can also be regarded as a special case of the RGB representation of color images.
The pixel color information in a digital media image, under the RGB color space model, is expressed as:
In the formula,
Accordingly, if the color information of any pixel in the digital media image is known, it can be decomposed into three component information of red, green and blue, as shown in Eq. (2):
In order to visually show the effect of a color image after decomposing RGB color information, an example situation as shown in Fig. 1 is given.
Decomposition effect of digital media image color information.
From the results in Fig. 1, it can be seen that after RGB decomposition, the original digital media color image becomes three component images, which can provide more features for similarity comparison. However, turning one image into three images increases the time for feature extraction and similarity comparison.
Based on the decomposition results of the color information of digital media images, the image similarity measure is carried out according to the wavelet basis, and the overall similarity measure is composed of two similarity sub-measures [12]. The first similarity sub-measure is used to compare the approximate wavelet-based feature
In the formula,
In the formula,
The two sub-measures are fused together to form an overall similarity measure, and the result is shown in Eq. (5):
In the formula,
Through the preprocessing steps in the second section, the image edge features and color information are obtained, and the image similarity measurement results are obtained. Based on the digital media image preprocessing results, the digital media image features are further visually retrieved.
Image feature extraction based on wavelet PCA
Image feature extraction is the basis and core of image retrieval technology. Broadly speaking, image features include text-based features (such as keywords, annotations, etc.) and visual features (such as color, texture, shape, object surface, etc.). Text-based image feature extraction has been deeply studied in the fields of database systems and information retrieval. On this basis, this paper uses the wavelet PCA method to extract image features [13]. The wavelet decomposition is to act on each pixel. Therefore, in the spatial domain, wavelet-based dimensionality reduction cannot distinguish different classes between adjacent pixels, while PCA can provide more local spatial information of different classes between adjacent pixels. Therefore, a new feature extraction algorithm combining wavelet decomposition and PCA dimensionality reduction is proposed, which is helpful for better image retrieval.
Assuming that the dimension of the original space
Calculate the covariance matrix of the original space
In the formula,
The eigenvalue
In the formula,
Arrange the eigenvalues in descending order, that is,
The final PCA transform can be expressed as:
In the formula,
After PCA transformation, the first few principal components contain most of the information, but they are a linear combination of individual information, while the latter principal components contain a small amount of information, and the last few are basically noise. After the traditional wavelet decomposition, the high frequency part has both noise and detailed information in the image. If all high frequency components are discarded, a lot of detail information will be lost. The method proposed in this paper is to perform PCA dimensionality reduction on the premise of fully retaining the image details. Its advantage is that it can retain the useful information contained in the image to the greatest extent. The specific implementation steps are shown in Fig. 2.
Dimensionality reduction of digital media image PCA.
According to the digital media image feature extraction results obtained in Section 3.1, in order to facilitate visual retrieval of image features and reduce retrieval complexity, image features are further fused. Assuming that
In the formula,
The features mapped by Eq. (10) are fused, and the result is shown in Eq. (3.2):
In the formula,
It should be pointed out that the dimensions of different eigenvectors are different, and the value ranges are also quite different. When they are merged into one eigenvector, they need to be processed according to certain rules. For example, the normalization process can greatly weaken the influence of the difference in the value range on the importance of different feature vectors. In addition, according to the actual situation of the image information, it is also possible to determine which feature vector accounts for the proportion of the fused vector.
Since the dimension of digital media images will increase accordingly after feature fusion, the eigenvalues and eigenvectors are usually solved accurately by the matrix method to achieve feature dimension reduction, but the biggest drawback of this method is that when the dimension scale increases, the amount of calculation is huge, which obviously reduces the efficiency of the algorithm. The basic idea of image feature dimensionality reduction method based on FPCA and ReliefF algorithm is: for a given image feature data, the feature is projected by using the linear transformation principle of FPCA algorithm, and the high-dimensional data is mapped to a low-dimensional subspace. This newly formed low Viterbi feature subset can effectively represent the original data information and eliminate the redundant information in the high-dimensional data, it can effectively reduce the dimension of image features.
FPCA algorithm is a multivariate statistical method that can transform multiple features into several comprehensive features with less information loss. The transformed comprehensive features (principal components) are linear combinations of uncorrelated original features, so as to reduce the dimension of digital media image features.
Assuming that a vector
In the formula,
Then the pivot variable
It can be proved that when the variance of
The implementation steps of the digital media image feature dimension reduction algorithm based on FPCA and ReliefF algorithm proposed in this paper are as follows:
Input the original data set Under the condition of ensuring the minimum correlation between the principal components, use the FPCA algorithm to reduce the dimension of Use the ReliefF algorithm to calculate the classification weight Arrange Judging the dimension of the subspace data, if
First, assume that the source image has
The form of
Schematic diagram of nonlinear function.
In Fig. 3,
In the same way, when
It can be seen from Eqs (16) and (17) that the parameter
To sum up, the nonlinear function can effectively implement active noise control and reduce the sensitivity to image noise [14]. By controlling the size of the parameters
According to the above image processing results, a visual retrieval platform for digital media image features is established [15]. The platform provides multiple retrieval portals, including tree list retrieval portals, image interface retrieval portals, and keyword retrieval portals. The image interface retrieval is realized by an Applet on the client side. The user can change the image center node through the mouse to visually browse the characteristics of digital media images. The visual image interface actually shows the class represented by the current node to the user. When the user selects and clicks a specific class in the tree list, the image display area will redraw the entire graph with the class name as the center.
The graphic display area provides the visual navigation and retrieval function of the ontology [16]. Figure 4 is the architecture diagram of the visual retrieval platform for digital media image features.
Architecture diagram of visual retrieval platform for digital media image features.
As can be seen from Fig. 4, the bottom of the user interface in the visual retrieval platform for digital media image features is the retrieval result output area. The user selects “detailed information” in the shortcut menu, and both keyword retrieval and SPARQL retrieval will be performed in this area. Output retrieval results, thereby realizing visual retrieval of digital media image features.
In order to verify the effectiveness of the visual retrieval method of digital media image features based on active noise control proposed in this paper, experiments are carried out.
Experimental environment and parameter settings
This test is carried out in the CloudSim cloud computing environment, the network bandwidth is 80 MI.S-1, the memory is 8 GB, and the operating system is Windows 8. The corel standard library is used as the experimental object to carry out experimental research. The Corel standard library is a standard open source library widely recognized in the field of image retrieval. There are 100 small categories and 10,000 images in the image library. Figure 5 shows some of the experimental images selected from the database.
Experimental sample image.
According to the above experimental conditions, the visual retrieval results of digital media image features by the method in this paper, the image retrieval algorithm based on multi-feature fusion and the image retrieval method based on joint weighted aggregation depth convolution features are compared. In the experiment, the precision rate, recall rate and retrieval effect are used as comparison indicators to compare the retrieval effect of different methods, and draw the experimental conclusion.
Precision comparison
Three methods are used for image feature retrieval, and the precision is the experimental index to compare the retrieval effects of the three methods. The results are shown in Fig. 6.
It can be seen from the comparison results in Fig. 6 that the precision of the three methods shows an increasing trend with the increase of the number of iterations. Although the precision of this method is lower than that of the image retrieval method based on the joint weighted aggregation depth convolution feature when the number of iterations is less than 3, the highest precision of this method is more than 80%, the highest precision of image retrieval algorithm based on multi feature fusion and image retrieval method based on joint weighted aggregation depth convolution feature are 56% and 45% respectively, which is significantly lower than that of this method. It shows that in the visual retrieval of data media images, this method can obtain more accurate retrieval results and provide users with more accurate retrieval results.
Recall rates comparison
Three methods are used for image feature retrieval. Taking recall as the experimental index, the retrieval effects of the three methods are compared. The results are shown in Table 1.
Recall comparison results
Recall comparison results
Precision comparison results.
Comparison of retrieval effects.
According to the data in Table 1, when using the method in this paper to retrieve data media image features, the highest recall rate is 95.2%; when using the multi-feature fusion-based image precision retrieval algorithm to retrieve data media image features, the highest recall rate is 89.7%; when the image retrieval method based on joint weighted aggregation depth convolution features is used to retrieve data media image features, the highest recall rate is 90.3%. From the above data comparison results, it can be seen that the recall rate of the method in this paper is higher, indicating that it can retrieve more image features and obtain more comprehensive retrieval results.
In order to further verify the performance of the method in this paper, three methods are used to retrieve the sample images shown in Fig. 5, and the results are shown in Fig. 7.
In the sample images shown in Fig. 5, the top images are all buildings, the middle images are all plants, and the bottom images are all animals. According to the retrieval results obtained in Fig. 7, the order of the images retrieved by the method in this paper is consistent with that in Fig. 5, indicating that the retrieval results are more accurate. The multi feature fusion method is mixed with some different types of images in image retrieval, and the retrieval results are biased. The retrieval results of the joint weighted aggregation depth convolution feature method are similar to those of the multi feature fusion method, and there is also the problem of confusion between different types of images. According to the above experimental results, this method has a very prominent retrieval effect.
Conclusion
In order to improve the recall rate and precision rate of image retrieval and improve the effect of image feature retrieval, a visual retrieval method of digital media image features based on active noise control is proposed. The edge feature information of the image is obtained by edge detection, the color feature information of the image is obtained by using the RGB color space model, the image features are fused, the fusion result is obtained, and the dimensionality reduction process is performed on the fusion result. The image is sharpened by the active noise control method. According to the image processing results, a visual retrieval platform of digital media image features is established to realize the visual retrieval of digital media image features. Experimental results show that the proposed method has the highest accuracy of more than 80%, and the highest recall rate is 95.2%. The precision and recall rate of the proposed method are higher than those of the traditional method, and it has better retrieval effect. Although this paper has achieved some research results, its image retrieval accuracy is still low. This is because when extracting image features, this paper only considers its color and other features, without fully analyzing its content. Further research will be carried out in the future.
