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    An Image Resizing Function Embedded in an Inverse Discrete Cosine Transform
    (2022-01-01)
    Sinchai, Ananta
    ;
    Tuwanut, Panwit
    Image resizing is an everyday activity and can be done in either a spatial domain or a transform domain. This work realizes that an image is commonly stored in the transform domain and the transformed image must be converted back to the spatial domain to display. This work hence proposes embedding an image resizing function based on a scaled frequency (SF) in a matrix operation of inverse discrete cosine transform (IDCT) for the sake of convenience. By adopting the proposed technique called as the SF-IDCT is not only capable of resizing the transformed image to a given resolution, but also acquiring the IDCT as a by-product. Image data can be shortened or lengthened in proportion to their frequencies by varying the frequencies of the DCT basis functions. Besides, the effects of modifying the pattern of the image data are also studied. The experimental results indicate that the SF-IDCT functions well. The proposed technique reconstructs an upsized image of equal or better visual quality than those produced by existing methods. For a downsized image, the performance of the presented approach is competitive with other available methods.
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    Medical image encryption based on DCT-DWT domain combining 2D-DataMatrix Barcode
    (2016-02-04)
    Nambutdee, Amarit
    ;
    Airphaiboon, Surapan
    In this paper, an application for medical image encryption and watermarking to store patient information is proposed. By using scrambling algorithm, the 1<sup>st</sup> view patient information is hidden and require unique patient password to access a real image. For watermarking scene, a Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are applied to non-overlapping block size 8x8 image pixels. Later, a DWT and DCT coefficient value are compared in each block for position identification of embed message in medical image. To improve high capacity and imperceptibility in watermarking step, a Two Dimension Barcode ECC200 standard is used to convert message before embed to cover image. Experimental results demonstrate that the proposed scheme achieves better performance of imperceptibility.
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    Remote sensing image retrieval using DCT-based texture descriptor
    (2016-01-01)
    Nuangnit, Atcharawan
    ;
    Rangsanseri, Yuttapong
    In this paper, we propose an image retrieval technique using texture descriptor extracted from a block-based Discrete Cosine Transform (DCT) of the image. To construct the texture descriptor, the absolute DCT coefficients are averaged over the entire image, and the feature vector is formed up by choosing middle-frequency elements of the zigzag-scanned DCT coefficients. This extraction is applied to both query image and all images in the archive. A distance function is used to measure the similarity between two images. This technique is successfully applied to remote sensing images downloaded from www.earthexpolrer.usgs.gov of Thailand regions.
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    Combined discrete cosine transform and two-piecewise companding transform for PAPR reduction in OFDM signals
    (2013-01-01)
    Thititummajariya, Wisan
    ;
    Chayratsami, Pornpimon
    The high peak-to-average power ratio (PAPR) is one major drawback of orthogonal frequency division multiplexing (OFDM) systems. In this paper, a new companding technique is proposed by using the combination of the discrete cosine transform (DCT) and two-piecewise companding (TPWC) transform. Computer simulation results show that the proposed scheme offers better PAPR reduction and also improve bit error rate (BER) and power spectrum density (PSD) performances compared with the ordinary companding method. © 2013 IEEE.
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    On-line writer identification system characterizing velocity and areal velocity in handwriting process
    (2009-12-01)
    Matsuura, Takenobu
    ;
    Thumwarin, Pitak
    In this paper,we propose an on-line writer identification system characterizing velocity and areal velocity of pen-tip movement in handwriting process. The writer identification system consists of two finite impulse response (FIR) systems characterizing the velocity and areal velocity in handwriting process. Individual handwriting feature is represented by the impulse response of the FIR system. Writer can be identified by evaluating the difference between the impulse responses of the FIR systems for the reference and a person to be identified. In our experiments 2,000 Thai numerals were used to identify 10 different writers.