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System-level model of hardware assisted still image compression based on two dimensional principal component analysis

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There are many storage formats for digital images in the PC environment, however hardly no one meets their specific nature. One of the most popular - JPEG/JFIF [13] - is a compromising solution: it gives high compression ratios while retaining acceptable visual quality [13]; its encoders and practical implementations are efficient and easy to use. On the other hand, JPEG has many limitations[...]

Open virtual steganographic laboratory

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Among many different applications where data hiding techniques can be used, one that has received huge attention in recent years is steganography. In that scenario, not just the embedded message is hidden, but the communication process itself is tried to be concealed. Steganography is both art. and science of undetectable communication [1]. Opposed to cryptography which encrypts a message, steganography achieves private communication by hiding message in cover object so not only content is known but also very existence of message. Throughout the history many different media types have been used to hide information. Nowadays steganographic applications [9,16] are using computer file system, transmission protocols, audio files, video files, text files or images, which are the mo[...]

An algorithm of face recognition under difficult lighting conditions

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The paper addresses the problem of face recognition for images with lighting problems - flashes, shadows and very low brightness level. Presented algorithm, allowing to eliminate above problems, is based on 2DDCT (two-dimensional Discrete Cosine Transform) supported by brightness gradient reduction, reduction of spatial low frequency spectral components and fusion of spectral features conditioned on average intensities. Presented experiments were conducted on image databases Yale B and Yale B+. Streszczenie. W artykule zaprezentowano zadanie rozpoznawania twarzy na podstawie obrazów uzyskanych w trudnych warunkach oświetleniowych, posiadających odbłyski, cienie i niski poziom jasności. Zaprezentowany algorytm pozwala na wyeliminowanie wymienionych problemów i bazuje na dwuwymiarowej dyskretnej transformacie kosinusowej połączonej z redukcją gradientu jasności, eliminację niskoczęstotliwościowych komponentów widma i fuzji komponentów widma zależnej od średniej jasności obrazu Jako uzupełnienie, przedstawiono eksperymenty przeprowadzone na bazach Yale B i Yale B+. (Algorytm rozpoznawania twarzy w trudnych warunkach oświetleniowych) Keywords: face recognition, illumination reduction, two-dimensional Discrete Cosine Transform Słowa kluczowe: rozpoznawanie twarzy, eliminacja oświetlenia, dwuwymiarowa dyskretna transformata kosinusowa Introduction One of the most crucial problems in face recognition practice is the variations of light intensity in input images processed by FaReS (Face Recognition System). In such situation we have to deal with two types of complications in the area of face and its background. The first one is related to local shadows, while the second one is associated with so called global shadows. Local shadows change the form of individual parts of face (nose, mouth, and eyes) and distort the boundaries of face area. Global shadows significantly reduce the discrimination of various face areas against general background a[...]

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