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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)
Describes the development of a technique for subband image coding called the symmetric extension method which utilizes the nature of a symmetrically extended image to achieve high quality coding. There are, however, some restrictions on the usable subband coding system. The development is done based on the property of a symmetrically extended signal in the(More)
SUMMARY In this paper, we propose a bit-rate adaptive coding system based on lossless DCT (L-DCT). Our adaptive coding system consists of three different operation modes: ÐÓ××¹ ÐÐ××, ÒÒÖ¹ÐÓ××ÐÐ×× and ÐÓ××Ý coding modes. Quantization is applied in transform domain (after the L-DCT) and spatial domain (before the L-DCT) in lossy mode and near-lossless mode,(More)
SUMMARY 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(More)
This report proposes a two layer lossless coding system for high dynamic range (HDR) images expressed in a floating point data format. Its encoder outputs compressed image data in two layers. From the base layer, a standard low dynamic range (LDR) image is decoded. Merging with the enhancement layer, the original HDR image is decoded without any loss. We(More)
In this report, we propose a reversible two dimensional (2D) discrete wavelet transform (DWT) compatible to the irreversible 9–7 DWT for lossy coding in the JPEG 2000. All the filters and scalings are factorized into lifting steps, and signals are rounded into integers, so that the proposed DWT becomes reversible and applicable to lossless coding.(More)
In this paper, a lossy data compression for a sparse histogram image signal is proposed. It is extended from an existing lossless coding which is based on a lossless histogram packing and a lossless coding. We introduce a lossy mapping, which has less computational load than the rate-distortion optimized Lloyd-Max quantization, and combine it with 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)