Liu Gang, Yan Guozheng, Zhao Shaopeng, Kuang Shuai
Technol Health Care. 2015;23 Suppl 2:S239-47. doi: 10.3233/THC-150959.
As an important part of the application-specific integrated circuit (ASIC) in wireless capsule endoscopy (WCE), the efficient compressor is crucial for image transmission and power consumption.
In this paper, a complexity-efficient and one-pass image compression method is proposed for WCE with Bayer format images. The algorithm is modified from the standard lossless algorithm (JPEG-LS).
Firstly, a causal interpolation is used to acquire the context template of a current pixel to be encoded, thus determining different encoding modes. Secondly, a gradient predictor, instead of the median predictor, is designed to improve the accuracy of the predictions. Thirdly, the gradient context is quantized to obtain the context index (Q). Eventually, the encoding process is achieved in different modes.
The experimental and comparative results show that our proposed near-lossless compression method provides a high compression rate (2.315) and a high image quality (46.31 dB) compared with other methods.
It performs well in the designed wireless capsule system and could be applied in other image fields.
作为无线胶囊内窥镜（WCE）专用集成电路（ASIC）的重要组成部分，高效的压缩器对于图像传输和功耗至关重要。
本文针对具有拜耳格式图像的WCE，提出了一种复杂度高效的单通道图像压缩方法。该算法是从标准无损算法（JPEG-LS）修改而来的。
首先，使用因果插值来获取当前待编码像素的上下文模板，从而确定不同的编码模式。其次，设计了一种梯度预测器，而不是中值预测器，以提高预测的准确性。第三，对梯度上下文进行量化以获得上下文索引（Q）。最终，在不同模式下实现编码过程。
实验和比较结果表明，与其他方法相比，我们提出的近无损压缩方法具有较高的压缩率（2.315）和较高的图像质量（46.31 dB）。
它在设计的无线胶囊系统中表现良好，可应用于其他图像领域。
