Somchart Chokchaitam

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In this paper, we propose a new one-dimensional (1D) integer discrete cosine transform (Int-DCT) for unified lossless/lossy image compression. The proposed 1D Int-DCT is newly designed to reduce rounding effects by minimizing number of rounding operations. The proposed Int-DCT can be operated not only lossless coding for a high quality decoded image but(More)
This report proposes a new coding method, which realizes lossless, near-lossless and lossy coding with a unified single algorithm. The method is based on a lifting-structured lossless DCT, which maps an "integer" input vector to also an "integer" output vector. The proposed method can be used as not only a high performance "lossless" encoder but also a(More)
Recently, the integer DCT (Int-DCT), which transforms an integer input to an integer output, is attracting many researchers’ attention as an effective method for DCT-based lossy/lossless unified coding. So far, there are many reports relevant to the Int-DCT, but they have been limited to a few topics such as how to reduce the number of multipliers with the(More)
While conventional DCT outputs real numbers and it is not suitable for lossless coding of images, the integer DCT (Int-DCT) outputs integer numbers and can serve as a lossless coding and lossy coding compatible to the conventional DCT. Recently, our group has proposed an optimum assignment method of word length of multipliers in the Int-DCT assuming(More)
The lifting structured wavelet transform (lifting wavelet) attracts researchers' attention as a key technology to a lossless and lossy unified coding system of digital image data. For VLSI circuit implementation, multiplier coefficients in the transform must be truncated into finite word length binary values. This report investigates how to appropriately(More)
In this report, we propose a non-separable twodimensional (2D) Lossless Symmetric Short Kernel Filter (L-SSKF) for image compression. Filter characteristics of our proposed L-SSKF are the same as those of conventional 2D L-SSKF based on applying 1D L-SSKF twice but our coding performance is better due to reduction of rounding effects. Simulation results(More)
Recently, we proposed a new multiplierless 1D Int-DCT modified from our existing Int-DCT by approximating floating multiplications to bit-shift and addition operations. The multiplierless 1D Int-DCT can be well operated both lossless coding and lossy coding. However, our multiplierless 1D Int-DCT is not focused on how to assign word-length for(More)
This report proposes a new lossless coding of images. The decoder can expand a rough image from a part of the bit stream (compressed data) and also it can expand the original image from the rest. This functionality is useful for progressive transmission of images or browsing images in a huge database. The new method is based on a reversible wavelet (RWT)(More)
Recently JPEG 2000 has adopted the integer wavelet to attain "lossless" coding of images. However existing DCT based "lossy" coding still prevails all over the world. This paper focuses on the integer DCT which can perform "lossless" coding maintaining compatibility to the "lossy" DCT coding. So far, we have optimized word length of each multiplier in the(More)