Performance Of JPEG Research Articles

Lossless Recompression of JPEG Images Using Transform Domain Intra Prediction.

JPEG, which was developed 30 years ago, is the most widely used image coding format, especially favored by the resource-deficient devices, due to its simplicity and efficiency. With the evolution of the Internet and the popularity of mobile devices, a huge amount of user-generated JPEG images are uploaded to social media sites like Facebook and Flickr or stored in personal computers or notebooks, which leads to an increase in storage cost. However, the performance of JPEG is far from the state-of-art coding methods. Therefore, the lossless recompression of JPEG images is urgent to be studied, which will further reduce the storage cost while maintaining the image fidelity. In this paper, a hybrid coding framework for the lossless recompression of JPEG images (LLJPEG) using transform domain intra prediction is proposed, including block partition and intra prediction, transform and quantization, and entropy coding. Specifically, in LLJPEG, intra prediction is first used to obtain a predicted block. Then the predicted block is transformed by DCT and then quantized to obtain the predicted coefficients. After that, the predicted coefficients are subtracted from the original coefficients to get the DCT coefficient residuals. Finally, the DCT residuals are entropy coded. In LLJPEG, some new coding tools are proposed for intra prediction and the entropy coding is redesigned. The experiments show that LLJPEG can reduce the storage space by 29.43% and 26.40% on the Kodak and DIV2K datasets respectively without any loss for JPEG images, while maintaining low decoding complexity.

A CUDA Implementation of DWT for JPEG 2000 Codec

In this paper, we propose a CUDA implementation of DWT for JPEG 2000 codec. We show that the performance of JPEG 2000 codec implemented by CUDA is better than CPU based implementation. The performance of the DWT implemented by CUDA is achieved 27.7 frame/second in 4K digital cinema.

Simple approach to improve the performance of JPEG

A simple approach to improve the performance of JPEG is proposed. In JPEG, quantized ac coefficients at high frequency generally have zero or small energies. Thus they contribute little or nothing to the peak signal-to-noise ratio PSNR. This implies that the bit rate can be reduced by discarding some high-frequency ac coefficients with little or no loss in PSNR. Based on this idea, we incorporate the concept of zonal coding into JPEG. This proposal is termed the zonal JPEG. In it, the coding scheme is identical to that of the traditional JPEG except that only a fixed number of coefficients are coded for each image block. Consequently, the proposed approach is totally compatible with the tra- ditional JPEG. It has two advantages over the latter: i better bit-rate utilization and ii achievable user-defined PSNR. These advantages have been verified by simulation results. © 2005 Society of Photo-Optical Instru-

Transmission diversity for JPEG 2000

A scheme for improving the performance of JPEG 2000 over noisy channels is presented. The detailed operation of the decoder based on a set of rules is provided. It is observed that the worst-case peak signal-to-noise ratio improves significantly compared to the conventional JPEG 2000.