Digital watermarking is a technique that embeds additional data into digital contents so that the distortion by embedding them is imperceptible, where the additional data are called watermark. One of the applications of digital watermarking is tamper detection and recovery. The digital watermarking methods for tamper detection and recovery can detect the tampered region in a tampered image and recover it. In this application, the digital watermarking methods solve the problem that digital contents can be tampered so that the falsification is not detected. In this manuscript, we propose a new method for tamper detection and recovery of JPEG images by using a RS code. The proposed method embeds the check symbols corresponding to an information-reduced original image into the LSBs of the quantized DCT coefficients in a JPEG image directly. Therefore the method completely extracts the embedded data from watermarked JPEG images. We investigated the performance of the proposed method in view of the image quality and the ability of tamper detection and recovery. The experiments of the image quality confirmed the imperceptibility of watermarked images and images used for recovery. The experiments of the ability of tamper detection and recovery confirmed the maximum size of recoverable tampered region and the difficulty of undetectable falsification.

The objective of this work is to embed watermark information into digital audio data as the deterioration of sound quality is not perceivable to human ears. Hence, we consider that watermark information is embedded in the consonance to melody line or bass line. Generally, unison, octave, perfect fifth and perfect fourth are called consonance and human ears can hardly feel annoyed for consonance. Hence, we focus on perfect fifth and perfect fourth in the consonance. For decision of embedding positions, we need to estimate tone pitches, and we use spectrogram analysis as a technique of automatic music transcription. We embed watermark information with perfect fifth or perfect fourth of consonance from the pitch which is estimated by spectrogram analysis, and we aim at good sound quality of watermarked audio signal without sense of discomfort. Therefore, we propose an audio watermarking method by using automatic music transcription information.

In this letter, a type-II hybrid broadcast automatic-repeat-request (ARQ) scheme with adaptive forward error correction (AFEC) using BCH codes is proposed and analyzed. The basic idea in the proposed scheme is to increase the error correcting capability of BCH codes according to each channel state using incremental redundancy. The numerical results for the analysis and the simulation show that the proposed scheme maintains high throughput even if channels become noisy and the number of receivers is large.

A hybrid automatic-repeat-request system combined with adaptive forward error correction (ARQ/AFEC) which adaptively alters the error-correcting capability according to channel state using a nonsystematic Reed-Solomon code is presented. lt is shown that the system can alter the error-correcting capability by varying the number of information symbols fed to the decoder only, and not change the hardware of the encoder. Performance evaluations indicate that the ARQ/AFEC system has much higher frame efficiency than ARQ without AFEC for low-bit error rate and has high frame efficiency in a wide range of bit error rates.>

In the PCM (pulse-code modulation) transmission system discussed, the influence of bit errors on the demodulated signal-to-noise ratio differs in the erroneous bit position. The demodulated signal-to-noise ratio can be improved when the PCM signals are protected so that the decoded bit error rate in more important bit position may be lower. Assigning a different number of orthogonal check sums to each information bit of self-orthogonal convolutional code provides a different error protection capability to each information bit. The author presents an unequal error protection self-orthogonal convolutional code with different error protection capability for each information bit, and discusses the condition that makes the demodulated signal-to-noise ratio of PCM signals maximum.>

A decoding method is proposed for the redundant residue polynomial codes, a class that includes Reed-Solomon codes. The method is based on properties of Euclid's algorithm. The advantage of the method is that the computation of both the error-locator polynomial and the error-evaluator polynomial needed in conventional decoding methods can be avoided. The method is suitable for decoding concatenated codes whose outer codes are redundant residue polynomial codes, since they are easily decoded by ignoring erasures detected in the inner codes.>

A class of single asymmetric error-correcting cyclic AN codes is proposed. These codes are designed for use on asymmetric channels, such as LSI memory protection. It is shown that they are equivalent to the Constantin–Rao codes generted by a prime field in which 2 is a primitive element. The advantage of these AN codes is that error correction can be easily made using arithmetic operations.

A construction method of asymmetric error-correcting codes is proposed. In this method, at-fold asymmetric error-correcting code of lengthn-1is constructed by expurgating and puncturing anyt-fold symmetric error-correcting code of lengthn. These codes are designed for use on binary asymmetric channels, such as large-scale integration (LSI) memory protection, on which transition is one-way.