4 results about "Dct transform" patented technology

This application provides a method, apparatus, and device for image dark watermarking based on DCT intermediate frequency difference modulation and pseudo-random spreading. The method performs Hamming error correction coding and key-driven pseudo-random spreading processing on the watermark information to be embedded to generate a spread-spectrum watermark bit sequence; it performs channel extraction and frequency domain representation generation processing based on discrete cosine transform on the original image to obtain a DCT transform coefficient matrix; based on the spread-spectrum watermark bit sequence, it performs intermediate frequency coefficient pair difference modulation embedding processing on the DCT transform coefficient matrix to generate a modulated frequency domain coefficient matrix carrying watermark feature information; it performs image domain inverse transformation reconstruction on each modulated frequency domain coefficient matrix and outputs a target image containing a dark watermark that is visually consistent with the original image. This application, through intermediate frequency difference modulation and spreading mechanisms, solves the shortcomings of traditional schemes in terms of visual invisibility, resistance to compression attacks, and security, significantly improving the robustness of the watermark.

A method of encoding a video stream in a video encoder is provided that includes computing an offset into a transform matrix based on a transform block size, wherein a size of the transform matrix is larger than the transform block size, and wherein the transform matrix is one selected from a group consisting of a DCT transform matrix and an IDCT transform matrix, and transforming a residual block to generate a DCT coefficient block, wherein the offset is used to select elements of rows and columns of a DCT submatrix of the transform block size from the transform matrix.

This application relates to the field of data compression technology, and in particular to a method, apparatus, device, and storage medium for seismic data compression. The method includes: acquiring co-offset seismic data; performing a two-dimensional DCT transform on the co-offset seismic data to obtain frequency-wavenumber domain data; processing the frequency-wavenumber domain data based on the SPECK compression algorithm to obtain primary coded data; and performing adaptive arithmetic coding on the primary coded data to obtain target compressed data. This application facilitates improved efficiency in real-time transmission and storage of seismic data.