The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The wavelet transform has been successfully used in the area of power quality analysis. There are many published papers with methods for power quality disturbance classification or harmonics measurement, which use wavelet transform. However, the properties of the wavelet transform can drastically vary from the choice of the wavelet. In this paper we analyze the influence of the choice of the wavelet...
In every computer-based power quality measuring system it is necessary to adapt the power line signals to the data acquisition (DAQ) card modules. Proper dimensioning of the signal conditioning circuit is essential because it strongly affects the measuring uncertainty of the system. The signal conditioning modules provide several functions, such as: attenuation, galvanic isolation, filtering, A/D...
In this paper an improvement of wavelet based methods for detection and classification of power quality disturbances is presented. In the feature extraction process wavelet analysis is also used as in the comparing methods. However, the feature vector is extended with three other coefficients in order to improve the accuracy of the algorithm. In order to evaluate the proposed method, large number...
This paper presents a method for TV commercial monitoring that utilize matching visual extracts to detect known commercials. These visual extracts, also known as visual hashes, are computed from the low-frequency part of both luminance and chroma video frame components. Our approach relies on the assumption that commercial breaks are delimited by known commercial bumpers. Video sequences containing...
This paper presents an adaptive lifting scheme, which performs integer-to-integer wavelet transform, for lossless image compression. We optimize the coefficients of the predict filter in the lifting scheme to minimize the entropy of the detail coefficients. The optimized coefficients depend on the auto-correlation structure of the image. The presented lifting scheme adapts to both horizontal and vertical...
This paper presents multi-scale edge detection method using an undecimated Haar wavelet transform. The use of undecimated transform improves the localization of detected edges when compared to the classical, decimated Haar wavelet transform. The presented method tracks for edges that exist at several dyadic scales, favoring edges at larger scales. Edge points are obtained by non-maximum suppression...
This paper presents an adaptive lifting scheme, which performs integer-to-integer wavelet transform, for lossless image compression. We optimize the coefficients of the predict filter in the lifting scheme to minimize the predictor's error variance. The optimized coefficients depend on the autocorrelation structure of the image. The presented lifting scheme adapts not only to every component of the...
This paper presents an adaptive lifting scheme for integer-to-integer wavelet transform, and its performance on lossless compression of digital images. We optimize the coefficients of the predict filter to minimize the predictor error variance for every image. The optimized coefficient depends on the variance-normalized autocorrelation function of the image. The proposed lifting scheme adapts not...
This paper presents three types of lifting schemes, which includes normal lifting scheme, integer lifting scheme and optimization of integer wavelet transforms based on lifting scheme. Paper also gives a comparison between these types of lifting schemes and their algorithms. To determine the quality of reconstructed images the PSNR ratio is introduced.
In this paper we present the collaborative learning model we are currently developing and implementing in digital signal processing course. Its major components are: reading quizzes to motivate students to prepare for class; short lectures focused on the most important or most difficult concepts in the reading; and in-class problem-solving exercises to reinforce important concepts. The first results...
This paper presents semi-fragile watermarking system for video authentication. We focus on protection and verification of the I-frame's integrity in MPEG-1/2 coded videos. Using the DC difference between blocks, we compute binary feature string with semi-fragile characteristics from the I-frames. We use this feature string as a key to generate binary watermark, and then robustly embed this content-dependent...
In order to increase security of the blind watermarking schemes for image authentication it is desirable to use image-dependent keys in the process of watermark generation. In this paper we propose a new watermarking method for image authentication where the watermark is generated using the image hash as a key. The robust image hash, invariant to legitimate modifications, but fragile to illegitimate...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.