A Lossless Version of the Hadamard Transform

| This paper presents a lossless block-transform coder based on the Hadamard transform that achieves a compression ratio as good as that of the current lossless JPEG-standard and about 10 to 20% lower than the currently best state-of-the-art technique Calic. The main advantage of the proposed technique is that it produces an embedded data stream which may be truncated to achieve lossy compression. Preliminary results obtained on the \lena" image show that the proposed scheme produces an image quality that is comparable to that of lossy JPEG for compression ratios up to 4, and only slightly worse for compression ratios in the range 4 to 10. This means that the proposed coder performs well over a wide range of compression ratios and is therefore a useful alternative for the lossy and lossless JPEG-standards in nearly-lossless coding or when lossless and lossy decoding must be supported simultaneously. Finally , the transform part of the proposed scheme requires fewer computations than lossy JPEG (and only slightly more than lossless JPEG). Keywords| Lossless and quasi-lossless image coding , Hadamard transform.