Image Mirroring, Rotation And Interpolation In The Wavelet Domain
Jacob, Theju Isabelle
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JPEG2000, the international standard for still image compression, uses the wavelet transform. The filters used in JPEG2000 for transformation are the 9/7 Daubechies filters and the 5/3 Le Gall filters. At present, to achieve image mirroring or rotation for images, one has to convert them back to spatial domain and proceed. This thesis presents methods by which it can be implemented in the wavelet domain, without extra computational complexity. To do so, one manipulates the transform domain coefficients so that the condition of perfect reconstruction still holds true. The thesis also discusses a method to achieve image interpolation, which would result in a higher resolution image from a lower resolution one. One manipulates the wavelet domain coefficients of the image for the same. For comparison purposes, one takes the low frequency component obtained after the wavelet transform of the image, which acts as the low resolution image, try to predict the rest of the components, and then reconstruct the original image. The reconstructed image is then compared with the original image.