Chee Sun Won

Efficient use of local edge histogram descriptor

The purpose of this paper is to show how the edge histogram descriptor for MPEG-7 can be efficiently utilized for image matching. Since the edge histogram descriptor recommended for the MPEG-7 standard represents only local edge distribution in an image, the matching performance for image retrieval may not be satisfactory. In this paper, to increase the matching performance, we propose to use the global and semi-local edge histograms generated directly from the local histogram bins. Then, the global, semi-global, and local histograms of two images are compared to evaluate the similarity measure. Since we exploit the absolute locations of edge in the image as well as its global composition, the proposed matching method is considered to be a more image content-based retrieval. Experimental results support this claim. Experiments on test images for MPEG-7 core experiment show that the proposed method yields better retrieval performance especially for semantic similarity.

Texture Descriptors in MPEG-7

We present three descriptors of texture feature of a region. Namely, the homogeneous texture descriptor (HTD), the edge histogram descriptor (EHD), and the perceptual browsing descriptor (PBD). They are currently included in the Committee Draft of the MPEG-7 Visual (ISO/IEC 15938-3). Each descriptor has a unique functionality and application domain. HTD and EHD describe statistical distribution of the texture and are useful for image retrieval application, while HTD is for homogeneously textured region and EHD is for multi-textured natural image or sketch. PBD is a compact descriptor suitable for quick browsing application.

A composite histogram for image retrieval

In this paper, we propose a composite histogram for image indexing and retrieval. The histogram represents the composition of edge and luminance features as well as colors in images. As a result of combining the different features of the image together, we can reduce the size of the histogram drastically without degrading the retrieval performance. Since the proposed histogram contains only 14 bins, it has great advantage in terms of memory and computational complexity in the image retrieval. Experimental results show that the proposed histogram with 14 bins yields better retrieval performance than the RGB color histogram with 256 bins and the HSV color histogram with 166 bins.

Extracting image features from MPEG-2 compressed stream

In this paper, we propose a new image feature extraction algorithm in the compression domain. To minimize the decompression process the proposed feature extraction algorithm executes only the parsing process to the compressed bit stream. Then, by just decoding dct_dc_size in the MPEG-2 bit stream, we can determine if there exists any abrupt brightness change between two DCT blocks. According to the Huffman table for the MPEG-2 encoder, as the difference of the dc values between two succeeding DCT blocks increases, it yields longer coded bits. That is, the length of the coded dc value is proportional to the brightness change between two succeeding DCT blocks. Therefore, one can detect an edge feature between DCT blocks by just decoding the information regarding the number of bits assigned to the difference of the dc values. To demonstrate the usefulness of the proposed feature extraction method, we apply the detected edge features to find scene changes in the MPEG-2 compressed bit stream.

Image retrieval using a novel relevance feedback for edge histogram descriptor of MPEG-7

In this paper, a relevance feedback method is proposed to improve the retrieval performance of the MPEG-7 edge histogram descriptor. Specifically, by updating the query point and the weighting factors simultaneously, we can reduce the convergence speed of the relevance feedback retrieval. Experimental results show that the proposed method improves the performance significantly for natural and clip art images.

Efficient color feature extraction in compressed video

In this paper, we propose a new image feature extraction method for MPEG compressed video. To minimize the MPEG decoding process, we use only DC values for Y, Cr, and Cb components for each macroblock. Then, we can obtain a feature vector, using the decoded DC values of Y, Cr, and Cb components, for all macroblocks in I frame. The feature vector consists of histograms for various colors, luminance, and edge types. In obtaining histograms for colors and luminance features, we consider the ratio of contributing pure colors and luminance to the chroma DC values for each macroblock. Then, we update all contributing colors and/or luminance histograms accordingly. Otherwise, if the macroblock is classified as an edge block, we update the corresponding edge type histogram. To demonstrate the performance of the proposed feature extraction method, we apply it to a scene change detection problem.

Composition of MPEG-7 visual descriptors for detecting adult images on the internet

We describe a similarity based adult image detection technique (SID) exploiting composed MPEG-7 visual descriptors. The technique with a large set of training adult image database and a smaller set of training non-adult image database is practically useful in detecting adult images with little false negatives. SID achieved 99% correct detections with 23% false positives when experimented with a database containing 1,300 training non-adult images, and 93.5% correct detections with 8.4% false positives when experimented with a database containing 12,000 training non-adult images. 9,900 training adult images are used for both experiments. Given a query, ten most similar images are retrieved. If majority of the retrieved are adult images, then the query is determined to be an adult image. Otherwise, it is determined to be a non-adult image. SID can detect adult Internet content with the aid of text filtering system as described in the later section.

MPEG-7 TEXTURE DESCRIPTORS

A texture description is useful in many applications including similarity based image search and browsing. We present here three texture descriptors that are being considered for the final committee draft of the ISO/MPEG-7 standard. A comprehensive overview of the syntax and semantics of these texture descriptors is provided. The Homogeneous Texture Descriptor (HTD) and the Edge Histogram Descriptor (EHD) are useful in similarity search. The HTD characterizes homogeneous texture regions and is also useful in texture classification and recognition. The EHD is applicable when the underlying texture is not homogeneous and can also be used in sketch based retrieval. In addition, a compact descriptor that facilitates browsing applications is also defined. These descriptors are selected after a highly competitive test and evaluation phase within the MPEG group and we briefly summarize the evaluation criteria, the datasets used and the experimental results.

Image retrieval using sub-image matching in photos using MPEG-7 descriptors

Regions of interest in photos are important clues for the content-based image retrieval. However, segmenting semantically meaningful objects in the photo automatically for the query and similarity matching is known to be an unsolved problem. As an alternative, in this paper, we propose a scheme to form a query region in the image space in terms of 4× 4 sub-images. The set of query sub-images, which include the region of interest in the image space, is used for the basic unit for the similarity matching. Specifically, the edge histogram descriptor and the color layout descriptor in MPEG-7 are used to extract image features in the chosen sub-images and are compared to those extracted from the test images in the database. Experimental results show that the proposed method can retrieve images with similar regions in the images, even if the background regions look quite different from each other.

Adaptive interpolation for 3D stereoscopic video in frame-compatible top-bottom packing

Stereoscopic 3D video is decimated by frame-compatible top-bottom packing structure. At the receiver the discarded horizontal lines are reconstructed by interpolation functions of parallax-compensated data as well as remained neighboring lines.